I mean yeah usually the feeling of suffocation comes from too much CO2 rather than too little O2. You can slightly extend how long you can hold your breath by exhaling at the end.
Worked in Oil and Gas, one of the stories we had drilled into us during safety meetings was the time when two welders at our site were given the go ahead to work on an exposed bit of pipe that was large enough for you to crawl into.
They go down and set up their gear but the sun is at just the right angle that its interfering with their work, so they get some plastic sheets and drape them over the end of the pipe where they are working in order to get some shade.
The main guy crawls in and lowers the plastic sheet and starts working. The secondary guy standing outside realises it's been a hot minute since he heard the main guy say or do anything so he lifts the sheet and sees his colleague lying face down in the pipe. He grabs his legs and pulls him out but its too late to save him, he's dead.
Turns out that the pipe still had a slow trickle of nitrogen being supplied to it, when the pipe was open to the air it wasn't enough to knock you out but when they put the plastic sheet over the end of the pipe it was enough to let the nitrogen slowly build to lethal levels.
Turns out your body doesn't register a lack of Oxygen, that feeling you get when you hold your breath is the build up of Co2 that you body is reacting to. When you breathe a near 100% nitrogen atmosphere you don't get any Oxygen but you still get rid of Co2. So you have no warning about what is happening to you and the worst part is the nitrogen in your lungs is not only not supplying oxygen but actively encouraging what little oxygen is in your system to be exchanged out, so you black out in seconds.
We got it drilled into our heads because the role I had at the plant was one of the guys who ran it and carried out safety checks before issuing permits to workers who then went into these confined spaces, It was to make sure that I would go and test the areas with the right equipment in order to ensure that the air was breathable. As a result of stories like that, I always double-checked everything before signing off on any permits on my site.
This happened to a crew of space shuttle ground crew technicians too, shortly before the first launch of STS-1. Crew compartment had been purged with pure nitrogen, and the technicians hadn't been warned.
Six guys in total entered and passed out. Three survived and were eventually okay. Two died 'directly' from the event, and a third was revived, but suffered debilitating brain damage that eventually killed him a few years later. This third guy was a goddamn hero who went back to drag his unconscious friends out even after he'd passed out once alread himself. The three that survived did so because of his actions.
So you have no warning about what is happening to you and the worst part is the nitrogen in your lungs is not only not supplying oxygen but actively encouraging what little oxygen is in your system to be exchanged out, so you black out in seconds.
Yep, the worst part is our lungs are not smart! They work to equalize gases in our blood with gases in our lungs.
No oxygen in lungs? lungs go "Hey lemme fix that, I got plenty of oxygen in this blood I can donate!"
You go out far quicker breathing pure nitrogen then you would holding your breath.
Sinister, sure. But I'll take sinister any day over "Opps your already dead, and so is the guy who walked in to rescue you after he took one breath without SCBA"
I held a Gas Free Engineer role back in the day and what really stuck with me was the displacement of oxygen. Confined spaces, especially with iron, can consume oxygen and becomes a space of denser molecules that, to put it simply, pushes the air out so quick you instantly pass out. Many a story on individuals climbing down in to test the air instead of lowering the detector down on a lanyard then quickly expiring.
I’m always surprised about how many people aren’t conscious of confined spaces and dangerous gases. Every year people in my town die from running a generator indoors or something like that, some sort of avoidable accident that causes CO build up. I’ve seen and corrected way too many accidents waiting to happen, mainly people running generators or other combustion indoors like idling a car in the garage without any ventilation. It’s something I was taught young since we had a wood burning stove for heat, but honestly common sense should apply here. Everyone knows exhaust isn’t good for you.
I used to do forensic engineering for a living. I've investigated many CO cases. They were always the worst. It's like a normal house, but there's dead people there.
"Fun" fact: during WWII the use of flamethrowers on bunkers was found to be astoundingly effective, much more so than it should have been. Turns out, shooting a flamethrower into the mouth of a sealed up bunker is a fantastic way to smother the whole thing in a cloud of carbon monoxide, which rapidly suffocates folks even deep down inside. This is one reason why flamethrowers are generally not used on the battlefield anymore.
the killer is invisible, silent, leaves no marks on the bodies, and left the room through the window and cracks in the door frame; maybe even slipping past the person to first make the discovery.
I’ve seen that too. Carbon Monoxide bodies do that to a certain extent too. I have never seen bright red, but certainly pink enough to simulate recent life that I started CPR on long dead people. On autopsy, even internal tissues were pinkish.
It’s because CO binds the oxygen in your blood. Your blood is carrying all the oxygen you could ever want but your cells can’t get any of it.
Edit: as pointed out below I misremembered the mechanism. CO binding with hemoglobin turns your blood cells bright red in a similar way to oxygenation but the cells are transporting CO instead of oxygen contrary to what I suggested above.
What got me about a carbon monoxide incident near where I grew up is, apparently the family presented with flu-like symptoms, so the advice was stay home, wrap up warm, keep the windows and doors shut, and run the central heating boiler that killed them.
We are in the middle of a wind storm and our neighborhood power has been out for going on 2 days. It’s also very cold here. It’s amazing to me the number of people who are trying to heat their homes with portable propane heaters and are unaware of the need to vent! It’s terrifying really. I work in a hospital and we are very afraid for the community right now.
I remember years and years ago I saw a comment on reddit from like either a search and rescue or police officer or something, cant quite remember. There was an ice storm and the power went out. He went around and tried to tell some people who were running generators indoors to not do that, and some of them became very combative. The people who refused to move the generator outside died with their families.
Technically, Darwin Awards are only supposed to go to people who die before they pass on their genes. I guess it still counts if you end up killing your family after you have kids, though.
Just a note for readers; it's not just Iron, iron is just very reactive with oxygen.
It's that oxygen itself reacts with almost everything, it's why it's our bodies fuel gas; it's crazy reactive, corrosive... It's literally just "a type of dangerous, corrosive gas that we evolved to use, because it's everywhere". It's so damn corrosive that it even slowly damages us as we consume it.
Oxygen will react (i.e. bind itself) to literally almost anything it touches. The only reason it ever stops is because either the local environment is saturated with oxidized particles (i.e. every single molecule the oxygen can touch has already been converted into it's oxidized form, like Rust or silicate oxide) or because the oxygen in the local environment has run out.
Human built confined spaces have a combo of lots of fresh, non-oxidized materials that are gonna be sucking up oxygen for ages to come AND low to little airflow. That's why they're lethal.
It just... Doesn't ever seem obvious at first. The natural assumption is just "oh but there's just normal air'.
Imagine all the stories about going into tombs and cursed caverns and people never coming out. Makes me wonder if gas build up in things like the pyramids led to many of the ominous stories about them.
I learned from one of those strange death TV shows that two bakery workers in Georgia, USA were play fighting with cocoa powder in the confined space of a closet which killed them because the particulate of the cocoa dust was so fine that it clogged their lungs.
To add to this - I learned the same rule of thumb - even if you have zero roof, anything you can't breathe that's heavier than air turns that into a confined space.
I'm a refrigeration tech and I have a bottle of nitrogen in the van with me at all times. That thing gets double and triple checked every time I touch it just in case.
It gets drilled into us pretty hard just how easy it is to die when the air in your lungs is replaced by some other gas, and it's not "I can hold my breath for several minutes so a few minutes in a no oxygen environment should be enough for me to get out." Its "I just breathed out air, then breathed in nitrogen, aaand I'm out."
You need to be tied to someone on the outside that can pull you if something goes wrong, without having to enter the confined space. That part is standard. I’m doubting the legitimacy of what this person said however, implying people pass out frequently in their workplace. There are strict standards for confined spaces. I am a metal fabricator and sanitary welder and I’ve worked in some sketchy places and I’m seriously doubting a company would allow employees to lose consciousness regularly.
It’s a thing, but it shouldn’t be the only control point. You start by making sure the atmosphere is safe or bringing in your own. The tether is then potentially for access but also to allow recovery if something happens. Like it’s a place with a potentially hazardous atmosphere so you check it and it’s safe now but you also know that it might change while a person is there. It would be difficult for them to get out as quickly as the atmosphere might change because it is a confined space so you have them wear a harness and tether so the crew outside can get them out. The actual passing out thing should be a rare occurrence, and you wouldn’t send another person in without their own air supply if someone else has already been injured. Some places have pretty lax safety standards though, so maybe it’s a thing some places.
And assisted suicide pods flood the air with nitrogen. You keep breathing to put that carbon out of your blood, but when you inhale you don't get oxygen back, and eventually you go lights out. Person can still panic though, but they probably load the person up on the good stuff to avoid it in the one place you can use it or something like that. 3 kg of crushed Valium up a nostril for the most powerful of naps.
Also benzos are not more bioavailable if you sniff them? Simply eat 3kg of Valium, and then fall asleep because you have put yourself into an inevitable food coma, and then die from the sedation.
Not even “generally”. The ability to detect CO2 is a readaptation of acidity chemosensors. Fish with gills just need to know to stay away from acidic water meaning it had too much CO2 dissolved in it. We are just fancy fish.
There are chemoreceptors for both, but CO2 and its effect on pH are more of the primary means of regulation. The body can sooner sense and respond to high CO2 than to (very) low O2.
This is why you can hold your breath a bit longer if you hyperventilate first (not a recommendation*). You dispel more CO2 and so that urge to inhale is delayed a bit.
I forget where I read it or heard it from but when the whole "alkaline" body craze was huge they said/wrote "If you want to know what alkaline feels like just hyperventilate. CO2 is carbonic acid, when you hyperventilate you expel more than usual, which makes your blood more alkaline."
Yes. Main reason why we've had so many loses during SaR training at the army. Some went to train apnea alone, which is a terrible idea because when they did it and also used hyperventilation then there's a high chance they pass out while underwater. The reason? Hyperventilation decreases the amount of CO2 inside the lungs slightly but enough to postpone the suffocation trigger. If the O2 runs out before the need for breathing kicks in, you blackout, you drown.
Thank you. I learned to scuba dive afterwards to figure out what happened and to overcome my fear of the water. Turns out it's called Shallow Water Blackout and just knowing that it was a thing with a name helped a lot. I also make sure to not scrub out my CO2 before I snorkel.
Search and Rescue, but yeah, it's shallow water. I didn't take the full SaR course, just the basic one, our depth limit was over 35m. The guys who took the full course, which included helocasting, diving, swimming, climbing and bunch of other techniques have it way worse, but the diving training is basically the same, and apnea training is also the same in both.
This may sound crazy but I'm glad to know this. If I'm ever lost in open water I was planning to go under and just start breathing or something. Dying out there of dehydration or shark sounds so terrible I'd just want to go quickly
Yep. The pathway we’ve identified is that the body is actually detecting elevated CO2 concentrations in the body (hypercapnia), and the resulting decrease in blood pH (acidosis). The change in pH opens channels in the brain and triggers the feeling of panic and suffocation. Lowered oxygen isn’t directly involved in that pathway, so it can happen even if you’re getting oxygen. And respiratory acidosis can be fatal in its own right, as the study mentions.
I seem to recall a paper I read years ago describing an apparent timer attached to the diaphragm, such that not exhaling for too long also triggers feelings of panic and suffocation, even if your blood is being oxygenated and CO2 is being removed via some other means. Alas I can't even remember what decade I read it, let alone where...
Partly correct. Your body will compensate for low oxygen levels. Heart rate will go up, you'll breath faster, blood pressure will go up. Its currently pneumonia/flu/RSV season. We have a variety of machines for each person depending on what they need. It's either oxygenation or ventilation.
Your overall drive to breath isn't to get oxygen in but to get co2 out.
Source: Work in respiratory and deal with ventilators/breathing/blood gas values (pH, co2, oxygen)
Agreed. Same thing happened with my dad. His o2 levels werent incresing due to lung collapse. We tried giving oxygen but he started having side effects with no o2 increase. Then doctors suggested bipap machines to pull co2 out by forcing lungs to breath, expand and push co2 out. His o2 levels got back soon enough with no o2 supplied.
You can actually breathe pure nitrogen and not ever realize it. You would just pass out and/or die depending on whether someone gave you a source of oxygen quickly enough.
Our atmosphere is about 78% nitrogen as it is, and about 21% oxygen. But pure nitrogen would be both unnoticeable and deadly to us. You would actually notice breathing pure oxygen long before you noticed breathing elevated levels of nitrogen.
CO2 dissolved in a liquid makes it acidic, so the discomfort and pain you get when holding your breath for a long time is actually your blood turning into acid as CO2 builds up in your body.
The acidity change is nowhere near enough to trigger pain from the action of the acid. Pain from the activation of pH-gated ion channels in the brain, on the other hand...
Yes, we have chemoreceptors that detect both, but we're much more attuned to the excess CO2. The body will adjust the heart rate and respiratory rate to try and compensate and stabilize our levels.
Aren't there suicide capsules that just fill with N2, because you won't notice you're asphyxiating, you just feel tired, and eventually fall asleep, then die?
Nitrogen will knock you out like the Propofol to put you under during wisdom teeth extraction. It’s insanely quick, and the symptoms often go unnoticed until it’s too late.
A few years ago I read an article about a young firefighter who had died in training. He was able to shout “I can’t breathe!” But was disregarded until unconscious.
I read this article shortly after the death of George Floyd and it has changed how I look at some situations.
When you only exhale after a long breathhold, you arent changing the composition of gasses in alveoli, and so you do not get a higher gradient difference between your pulmonary arterial blood and the alveoli (where the exchange should take place).
If we want to be very technical there are some effects of the negative pressure that you are “releasing”, which will have an effect through a reflex arc on your heart muscle contractions. Through 3-5 nerve pathways this decreases your felt “Air hunger”, some lf that being funny medullary instabilities, some of it being normal vagal/parasympathetic tone.
But no, you dont dump more CO2 by breathing out there, because that CO2 was alresdy dumped “outside” your blood (in alveoli) and what makes you dump more is the *inspired air’s lower CO2 partial pressure.
In fact… exhaling will PREVENT more gas exchange because the total reservoir in the alveoli becomes smaller and so any gas exchange which did not yet reach equillibrium is SLOWED DOWN by exhaling - until the inhalation it allows it to restart on a fresh gradient.
Huh this is interesting. I knew that the feeling comes from CO2 and that breathing out eases that feeling. What I said felt like a pretty safe assumption but I guess that's not the case.
That is interesting. I do see that the study only examines if pressure was applied and where without looking specifically at the degree to which pressure was applied. Could there possibly be a way to ethically quantify this in a lab setting? Please clarify.
What was that comedy like 20 years ago training to go to mars and they're seeing how long they can exhale holding up a ping pong ball and the main character is kicking and flailing and hits the other astronaut
Swedish police is trained to know this. Its a part of their curriculum to run around and then be sat on - to show the experience. They are trained to sit on the shoulder, not the back or chest, and absolutley not the neck.
Yet 52 people during the last 30 years have died during these circumstances by Swedish police.
Yet 52 people during the last 30 years have died during these circumstances by Swedish police.
Not quite, the study is not limited to police. From Section 3.2:
In 31 cases (60%), the police authority conducted the restraint; six cases (12%) occurred with security guards, four cases (8%) occurred with nursing staff, and four (8%) with prison guards. The remaining cases were a combination of police with security guards (2 cases, 4%), police with nursing staff (2 cases, 4%), and with civilians (4 cases, 8%).
The police is however ultimately responsible for interventions where police officers take part even if it is together with security guards, medical staff or civilians and must take control of the situation and ensure that others such as those holding suspected offenders do not injure them and so on.
I took care of adults with mental handicaps, as part of our training they taught us about how to restrain someone safely and about positional asphyxiation. I find it hard to believe that police don't know, they just don't care.
It might be hard to believe, but it's a lot harder to safely restrain someone who is experiencing drug-induced psychosis than people with mental handicaps. Especially when it's just yourself or one other person in an uncontrolled environment Where they could have weapons or be trying to cause harm to their parties.
I have also spent quite a lot of time working with people with mental handicaps, it's a lot easier to deescalate them when you are in a controlled environment and you have 10 staffembers 30 seconds away.
It might be hard to believe, but it's a lot harder to safely restrain someone who is experiencing drug-induced psychosis than people with mental handicaps.
I always knew this was the case, but the actual visible reality imprinted on me a month ago, when four bouncers at my place of work struggled to restrain one individual in the middle of an angry, drug-fueled psychosis.
Seeing a single man of maybe 80kg(175lbs), toss another man of well over 100kg(220+ in freedom units) over his shoulder, while standing upright, was quite the sight. Watching them trying and failing to simply handcuff this man for ten minutes really showed what the human body could do when it throws away all sense of self-preservation and pain.
four bouncers at my place of work struggled to restrain one individual
I've been a bouncer in that situation before. Its even harder for us because we're not allowed to strike a suspect while they beat us back and we don't get the cop privileges of determining necessary force during an arrest because when we do it its a "Citizen's arrest". Its not uncommon for cops to arrest bouncers just cause...
It's 1-2 avoidable deaths per year. They still died to police brutality, no need to defend pointless deaths.
Not necessarily. In many of these cases there was no pressure applied at all by the police, and CPR was attempted. You can see it in the table if you scroll down a bit. Those deaths were probably not avoidable, and were not police brutality. It's possible for deaths to occur while still doing everything right.
Population size is loosely comparable (~15% more Swedes). NYC cops kill about 10/year, and Swedes about 3/year in recent years. But NYC also has 3x the # homicides. Presumably higher criminality means more situations in which a police officer is justified/required to use lethal force, so comparing homicides vs deaths at police hands feels more accurate.
Or for another proxy, you might say "police are justified in using lethal force when their lives are in danger", so you would look at # officers killed in the line of duty per year (which will correlate with the number of such situations) vs deaths at police hands. In all of Sweden, the number is roughly 1 per 7 years, or 0.14/year. In NYC the number appears to be about 1.6/year, or ~11x that, which would yield "For every officer killed in Sweden, police kill 21 individuals. For every officer killed in NYC, police kill 6 individuals".
Good analysis. I like the way you explained the process and rationale used to combine data and form a more comparable statistic. It's no longer an "apples to oranges" comparison. Maybe "apples to pears" now? You mentioned a 15% population discrepancy, and others have commented on population density.
It highlights the fact that while a "per capita" comparison, especially with similar population sizes, gives more detail than raw values, it still usually doesn't tell the whole story.
However, data can be used to manipulate conclusions. I'm sure the "number of individuals killed by police" statistic could be combined with something else to flip the resultant stasticic around again.
Just in case it needs to be said explicitly: I'm not making any attempt to justify or absolve the NYPD or Swedish police of police brutality. The numbers absolutely can and should be lower.
I doubt combinations of many salient variables would cause the NYC police to look worse when accounted for, because I honestly don't believe that the NYC police force is inherently ">3x as murderous" as their Swedish counterparts.
That said, your point about statistics being easy to manipulate is spot on. As seen in things like Monty Hall or Simpson's Paradox (i.e., batting averages), even very educated readers can misjudge what numbers actually tell us.
It seems like we already know this in part. After a treadmill cardiac stress test we have to lay down flat on our backs and not move. It’s highly uncomfortable and adds to the “stress” of the test.
There is absolutely a safe way to test this: you enter the scenario with monitoring equipment and end it before it becomes dangerous. There is a wide margin between "briefly uncomfortable and on the way to dying if you were to continue" and "actually dying". Like, they can and do perform tests that bring people to the edge of hypoxic brain death, because we know what the safe ranges are, where the unsafe range starts, and where the "sudden death without warning" range starts
My friends could breathe fast and press their chest against a wall and pass out. (Not safe, and we told them so). It does not take much to cause this from having seen it and it sounds similar. (Granted for my friends they were young kids and the pressure was released immediately).
purely anecdotal, but a good friend of mine died after running from the police. They caught him, restrained him, and pepper sprayed him. He was 27 years old and in good shape physically.
It would be difficult to test a causal effect for the reason you describe (rare population) but we could test whether the odds of dying after physical exertion are proportionally greater than the odds of dying after no physical exertion, which could be relevant.
Saw a video about this years ago. I forget the exact details, but someone who was an expert on breathing said that breathing is more expelling Co2 and not actually inhaling oxygen. I thought they said something about how we don't even really need to breathe that much to get sufficient oxygen.
Our mammal lungs are wet sacks that never empty out all the old air. They aren't that efficient, about 40%, so yeah, most of the oxygen that you breathe in goes unused. This is why CPR works, you still have lots of O2 in your lungs to give to them.
My understanding is that it's because it's pretty common for the victim to throw up while the other person gives CPR, and they don't want people not doing it. That's what I was told, I used to have to keep certified on it. It does give the person oxygen, it's just not as critical as they used to think, and better to do just chest compressions than skip it entirely.
The difference is whether the course is regular CPR or healthcare provider CPR. Laypeople are no longer advised to perform rescue breathing but it is still part of provider CPR and ACLS protocols. And the main reason isn't airway protection even though that does happen. The main reason is the effectiveness of chest compressions. It takes time to build up effective perfusion pressure, and especially for laypeople every time they stop to deliver breaths perfusion drops back to zero. Because blood retains some oxygen content even during arrest, it is better to maintain constant effective compressions than to try and deliver rescue breaths with ineffective perfusion.
During my emergency first aid training a year ago my instructor claimed that the increased gas exchange is not worth the repeated pauses in compressions. Apparently blood pressure quickly drops to zero when you stop, and it then takes many compressions for it to build up again, so it’s better to only focus on the compressions until paramedics arrive
You are right, but I do want to point out that one random course teaching something does not make it a standard.
All of that said, I did find this study which mentions that including rescue breathing in CPR as a bystander led to worsened outcomes. Chest compressions are by far and away the most important aspect of CPR.
Red Cross or AHA? Red Cross doesn’t update their information as frequently as American Heart Association. For this reason, most clinicians that are required to have a CPR card cannot use Red Cross.
That’s just for laypeople though, because the reality is it’s quite difficult to administer effective rescue breaths while maintaining good CPR quality.
Breathing is still very much part of what medically trained people will do during full resuscitative efforts AKA ACLS.
Isn't this why CPR was changed to just chest compressions only?
I did a CPR course a few years ago for work, and they said at the time that simply doing chest compressions and no rescue breaths would still provide enough oxygen, because you're compressing and releasing the chest and lungs, which pulls in enough oxygen from that action alone.
So stopping pumping the heart to give rescue breaths wasn't the most efficient course of action.
I did a CPR course at work (hospital) a couple of months ago, and we were taught to give two breaths for every 30 compressions, so I guess it varies depending on your governments guidelines.
I saw someone say recently that the recommendation in their area was for trained people to do the rescue breaths and compressions, and random passers by on the street should just do compressions.
Apparently reluctance to give “mouth to mouth” was putting people off helping at all, either because the victim was vomiting or unclean, or they were concerned about disease and infection, or they thought they could be sued for sexual assault.
It does help, but it is like 2% survival rate increase level of help. Not worth it when you don't know the other person's medical history, would probably be worth it if it is someone you know who is healthy or if you carry one of the masks for it.
By far the most important part is getting compressions started
Every single time I've gotten CPR training they've taught something different about the rescue breathing. Not that frequently, to be clear, but still funny.
Your memory is correct. If we just need to get oxygen we could probably breathe once per minute or less, but you can’t get rid of CO2 by breathing that slowly, and our body will trigger more rapid breathing when it senses extra CO2. It’s also why most of us breathe faster when exercising (I say most of us because elite athletes are limited by oxygen in certain cases).
This is what an asthma attack is like for me. I can inhale plenty of oxygen, I just can't get the carbon dioxide out. It's like trying to exhale through a coffee stirrer.
This description closely resembles the circumstances surrounding the death of Zak Kostopoulos, an LGBT activist and drag performer, who died after a violent encounter in central Athens, Greece, when he was violently apprehended, pinned to the ground by nine police officers, and beaten again.
In Zak Kostopoulos’ case, although the official forensic findings attribute his death to trauma-induced heart attack, the Swedish study challenges the common assumption that he died because he could not get oxygen in; instead, the lethal mechanism may be his body’s inability to rid itself of carbon dioxide under violent restraint. The Swedish review shows that in 90% of cases, where "prone restraint" (i.e. the person face down, restrained) was involved, the combination of body weight and restraint — especially prone + force — can cause cardiac arrest even in otherwise healthy individuals, due to inability to eliminate CO₂ (hypercapnia + acidosis), not necessarily hypoxia.
Interestingly, in the footage of Hellenic Police restraining Zak Kostopoulos, he was held face-down shortly before he lost consciousness, which aligns with the risk factors described in the Swedish study. It seems Zak Kostopoulos was murdered by Greek police officers...
Could this be related to anxiety tetany? I just got to experience the joy of that after my nerve blocker wore off post surgery. The pain caused a panic attack, I hyperventilated so bad that the build up of co2 caused my hands to seize up and my whole body to go numb. I was convinced I was going to die. Didn’t know it was a thing until after.
Panic attacks actually cause low CO2 levels, not high CO2. This is still not ideal because it raises the PH of your blood, and your body responds to this by constricting blood vessels. This leads to numbness and tingling along with shortness of breath and dizziness.
Luckily its not dangerous and the worst thing that can happen is you pass out, which will allow your body to go back into a normal respiratory pattern and your CO2 levels will return to normal.
Wouldn’t it be “off and on again”, since you are technically already “on” during the panic attack when the “system reboots”, so to speak?
Not trying to be combative or nitpick btw! I suffer from frequent panic attacks and this is just kinda how my own brain has always viewed it. I actually used this analogy once when trying to explain it to my Dad, who spent most of his career as a computer engineer.
No, your anxiety from the pain after your block wore off likely led to psychosomatic issues with your hands and body seizing/numbing. Hyperventilation is a compensatory mechanism to get rid of too much CO2. It doesn't lead to CO2 increase, it's the exact opposite. Your hyperventilation didn't start with too much CO2 unless you had other underlying issues (neurological, respiratory, cardiac). The hyperventilation was likely an expression of your panic/anxiety.
Wow first person I have ever heard that’s also experienced it. I have 4 tetany episodes in total in my life, and yes , fingers hands, toes, feet and my tongue all went into a full cramp as I flopped on the floor and was sure that death was about to happen.
I also had no idea what it was until many years later, I did have an ambulance called each time by somebody else nearby because obviously it looks like a seizure a little bit.
Weirdly, I think I actually caused them for two different reasons on the different occasions. On day one ,I had three of the four tetany episodes. I was for certain not hyperventilating I remember just being at work and I got extreme pins and needles in my hands and it went from there. I believe I had altered my blood chemistry because I went on a two week drinking and bad diet after a break up.
Years later, the fourth time out of four that it happened I was definitely hyperventilating and that caused it as well
This exact same thing happened to me after a big hike in the middle of summer. Thought I was dying and rushed to the ER. Tests came back normal and the doctors just kind of shrugged and said, “maybe heatstroke.”
I’ve had panic attacks for over 10 years but I’ve only this symptom once, it was about 2 years ago and luckily I was at a friend’s house.
When it happened I was freaking out but he told me that it’s a panic attack, I told him this isn’t like any panic attack I’ve ever had in my life, I’m dying. He said no it'll go away within 30 mins. And it did. I was sore in my hands and calves and back for days afterwards.
He told me he gets that kind of panic attack all the time. I can’t imagine.
In confined space training we were shown videos of people who were exposed to hypoxic atmosphere for a few seconds. They were possibly seconds from death and showed absolutely zero distress, if anything were comfortable and slightly elated. Your body has no way of measuring O2, it can only detect the build up of CO2 in the blood which elicits the breath distress response.
This actually makes the whole “but they were talking so they could breathe” argument even worse, not better. If CO₂ retention is the main mechanism, people can sound “ok” right up until they crash. Curious how big the sample is and how generalizable Swedish arrest practices are.
“Talking means they can breathe” was actually originally something that healthcare professionals (at least nurses) have been taught for a looooong time, but mostly in the context of choking on foreign objects, and not as a substitute for considering other issues affecting gas exchange as a whole.
It’s not entirely wrong, but it’s oversimplified - apparently dangerously so.
If someone is talking, their airway is open enough that they are also moving air in and out, i.e. breathing. They may still not be moving enough air out to adequately expel CO2, which is obviously still a serious issue that needs to be addressed right away (and there are also so many other medical issues that can lead to CO2 building up dangerously in the body that aren’t airway-related at all).
But in a healthcare setting, there might actually be merit to distinguishing “literally can’t breathe (at all)” from “is currently breathing but still has an urgent airway problem that needs to be addressed.” It’s possible that it could be used to guide difficult decision-making in resuscitation situations (like determining if a foreign object has moved from partially blocking to fully blocking the airway or vice versa, knowing how immediately to resort to doing an invasive surgical airway, etc.).
The key is that in a medical setting, there would be professionals around who also understand that “talking = breathing” isn’t an end-all-be-all (e.g. that you can still die, quickly or slowly, of respiratory acidosis due to pneumonia/asthma/MG/drugs while still being able to talk and express your shortness of breath), as well as a focus on monitoring/treating people and the availability of equipment/personnel to address it.
In a medical setting, it will be apparent and noticed when someone goes from saying “I feel like I can’t breathe” to beginning to lose consciousness (SpO2 drops, people become less alert, etc.).
Meanwhile, cops restraining people often have them lying face-down pushed into the ground. With zero monitoring of vitals. And with ridiculously oversimplified training on respiration physiology that was never meant to apply to law enforcement settings.
“If someone can talk, they can breathe” was never meant to be taken to mean that a person’s breathing is totally fine/adequate, and especially not to justify an extended period of restraint in a position that physiologically stresses the respiratory system (performed by people who aren’t healthcare professionals who can’t even see/hear/monitor/assess the person because they have them face-down and their face shoved into the ground).
This phrasing/teaching has approximately zero appropriate place in law enforcement training for these reasons, imho - not because it’s universally wrong/useless in all professions and settings, but because it is a recipe for disaster in the hands of even well-meaning law enforcement officers.
Sadly, at this point, I think it’s going to be damn near impossible to eradicate this idea from policing given how ingrained it’s been in all first responder/first aid training and how oft repeated it is.
Yeah, that makes sense in the original “partial vs complete obstruction” context. The problem is it got memed into a binary safety check instead of a very narrow heuristic, then exported into a setting where restraint itself degrades ventilation and nobody has monitoring. Classic bad-systems story: a crude rule of thumb leaks out of its domain, loses all its caveats, and becomes a shield for obviously dangerous behavior.
The people that needed to understand this about that case don't really care about science or reality, unfortunately. Even to this day, those people still believe you can't say anything while suffocating just because it supports their narrative. Dark times.
In the US the police and taser industry invented a fictional medical concept to explain police deaths in custody called 'excited delirium'. It's existence is widely rejected by most medical associations. It's not recognised at all in most countries outside the US.
Further study showed that most deaths attributed to excited delirium occurred in the context of inappropriate restraint by police.
I still see paramedics on /r/ems who swear excited delirium is real.
Also. You can still talk without being able to breathe in. Try it. Exhale all the air you can as hard as you can untill you cannot speak. Then, wait a few seconds and try to speak. You' be able to talk from tbe expelled CO2 in your lungs
I mean, there’s also a misconception that if one can speak, once can breathe. This study exploring the difference helps show you can still talk while having difficulty exhaling CO2.
So the distinction seems to be that if someone can tell you they can’t breathe, you should believe them. Which cops have not always done…I think that’s why this sort of study is important even though it feels like a “distinction without difference” at first glance
It's important to publicize the difference, because their conclusion is "even though they practically were able to get enough oxygen, the cause of death was a heart attack caused by having their respiration blocked at all after high stress extreme exercise" this will inform police restraint procedures more & better than a belief that lack of air intake is causing those deaths, because it's going to be seen as dangerous to even kneel on someone's back or sternum etc if they're out of breath as well as factoring in how out of breath the person is at the time of restraint.
I mean yeah usually the feeling of suffocation comes from too much CO2 rather than too little O2. You can slightly extend how long you can hold your breath by exhaling at the end.
I was recently told by a realiable party that the human body doesn’t generally notice a lack of oxygen, but rather just the excess of co2
Yeah this is why non-CO2 inert gases are so dangerous, such as a welder filling an enclosed space with Argon.
Worked in Oil and Gas, one of the stories we had drilled into us during safety meetings was the time when two welders at our site were given the go ahead to work on an exposed bit of pipe that was large enough for you to crawl into.
They go down and set up their gear but the sun is at just the right angle that its interfering with their work, so they get some plastic sheets and drape them over the end of the pipe where they are working in order to get some shade.
The main guy crawls in and lowers the plastic sheet and starts working. The secondary guy standing outside realises it's been a hot minute since he heard the main guy say or do anything so he lifts the sheet and sees his colleague lying face down in the pipe. He grabs his legs and pulls him out but its too late to save him, he's dead.
Turns out that the pipe still had a slow trickle of nitrogen being supplied to it, when the pipe was open to the air it wasn't enough to knock you out but when they put the plastic sheet over the end of the pipe it was enough to let the nitrogen slowly build to lethal levels.
Turns out your body doesn't register a lack of Oxygen, that feeling you get when you hold your breath is the build up of Co2 that you body is reacting to. When you breathe a near 100% nitrogen atmosphere you don't get any Oxygen but you still get rid of Co2. So you have no warning about what is happening to you and the worst part is the nitrogen in your lungs is not only not supplying oxygen but actively encouraging what little oxygen is in your system to be exchanged out, so you black out in seconds.
We got it drilled into our heads because the role I had at the plant was one of the guys who ran it and carried out safety checks before issuing permits to workers who then went into these confined spaces, It was to make sure that I would go and test the areas with the right equipment in order to ensure that the air was breathable. As a result of stories like that, I always double-checked everything before signing off on any permits on my site.
This happened to a crew of space shuttle ground crew technicians too, shortly before the first launch of STS-1. Crew compartment had been purged with pure nitrogen, and the technicians hadn't been warned.
Six guys in total entered and passed out. Three survived and were eventually okay. Two died 'directly' from the event, and a third was revived, but suffered debilitating brain damage that eventually killed him a few years later. This third guy was a goddamn hero who went back to drag his unconscious friends out even after he'd passed out once alread himself. The three that survived did so because of his actions.
Yep, the worst part is our lungs are not smart! They work to equalize gases in our blood with gases in our lungs.
No oxygen in lungs? lungs go "Hey lemme fix that, I got plenty of oxygen in this blood I can donate!"
You go out far quicker breathing pure nitrogen then you would holding your breath.
Hypoxia is even more sinister because when you get low on oxygen your brain still thinks it is fine.
Smarter Everyday YT channel has a great video on it
Sinister, sure. But I'll take sinister any day over "Opps your already dead, and so is the guy who walked in to rescue you after he took one breath without SCBA"
A silent killer, but relative to industrial accidents that story is one of the least traumatic ways to go at least.
I held a Gas Free Engineer role back in the day and what really stuck with me was the displacement of oxygen. Confined spaces, especially with iron, can consume oxygen and becomes a space of denser molecules that, to put it simply, pushes the air out so quick you instantly pass out. Many a story on individuals climbing down in to test the air instead of lowering the detector down on a lanyard then quickly expiring.
Confined space training for everyone.
I’m always surprised about how many people aren’t conscious of confined spaces and dangerous gases. Every year people in my town die from running a generator indoors or something like that, some sort of avoidable accident that causes CO build up. I’ve seen and corrected way too many accidents waiting to happen, mainly people running generators or other combustion indoors like idling a car in the garage without any ventilation. It’s something I was taught young since we had a wood burning stove for heat, but honestly common sense should apply here. Everyone knows exhaust isn’t good for you.
I used to do forensic engineering for a living. I've investigated many CO cases. They were always the worst. It's like a normal house, but there's dead people there.
"Fun" fact: during WWII the use of flamethrowers on bunkers was found to be astoundingly effective, much more so than it should have been. Turns out, shooting a flamethrower into the mouth of a sealed up bunker is a fantastic way to smother the whole thing in a cloud of carbon monoxide, which rapidly suffocates folks even deep down inside. This is one reason why flamethrowers are generally not used on the battlefield anymore.
let me guess. it's because commanders are usually in bunkers.
the killer is invisible, silent, leaves no marks on the bodies, and left the room through the window and cracks in the door frame; maybe even slipping past the person to first make the discovery.
it even SOUNDS eerie.
CO dead bodies are bright red.
I’ve seen that too. Carbon Monoxide bodies do that to a certain extent too. I have never seen bright red, but certainly pink enough to simulate recent life that I started CPR on long dead people. On autopsy, even internal tissues were pinkish.
really? that's pretty wild, thanks for the info. What an interesting "fingerprint" to leave at the scene.
It’s because CO binds the oxygen in your blood. Your blood is carrying all the oxygen you could ever want but your cells can’t get any of it.
Edit: as pointed out below I misremembered the mechanism. CO binding with hemoglobin turns your blood cells bright red in a similar way to oxygenation but the cells are transporting CO instead of oxygen contrary to what I suggested above.
The livores are bright red, the bodies themselves usually just look "healthy".
What got me about a carbon monoxide incident near where I grew up is, apparently the family presented with flu-like symptoms, so the advice was stay home, wrap up warm, keep the windows and doors shut, and run the central heating boiler that killed them.
We are in the middle of a wind storm and our neighborhood power has been out for going on 2 days. It’s also very cold here. It’s amazing to me the number of people who are trying to heat their homes with portable propane heaters and are unaware of the need to vent! It’s terrifying really. I work in a hospital and we are very afraid for the community right now.
I remember years and years ago I saw a comment on reddit from like either a search and rescue or police officer or something, cant quite remember. There was an ice storm and the power went out. He went around and tried to tell some people who were running generators indoors to not do that, and some of them became very combative. The people who refused to move the generator outside died with their families.
Darwin strikes again.
Technically, Darwin Awards are only supposed to go to people who die before they pass on their genes. I guess it still counts if you end up killing your family after you have kids, though.
Even going into an old steel tank can kill you. When iron rusts, it pulls oxygen out of the air.
Just a note for readers; it's not just Iron, iron is just very reactive with oxygen.
It's that oxygen itself reacts with almost everything, it's why it's our bodies fuel gas; it's crazy reactive, corrosive... It's literally just "a type of dangerous, corrosive gas that we evolved to use, because it's everywhere". It's so damn corrosive that it even slowly damages us as we consume it.
Oxygen will react (i.e. bind itself) to literally almost anything it touches. The only reason it ever stops is because either the local environment is saturated with oxidized particles (i.e. every single molecule the oxygen can touch has already been converted into it's oxidized form, like Rust or silicate oxide) or because the oxygen in the local environment has run out.
Human built confined spaces have a combo of lots of fresh, non-oxidized materials that are gonna be sucking up oxygen for ages to come AND low to little airflow. That's why they're lethal.
It just... Doesn't ever seem obvious at first. The natural assumption is just "oh but there's just normal air'.
But it ain't normal any more.
Same with rotting potatoes in old dirt cellars.
Imagine all the stories about going into tombs and cursed caverns and people never coming out. Makes me wonder if gas build up in things like the pyramids led to many of the ominous stories about them.
I saw a news article recently about rare fungi growing on poorly preserved mummies in a museum. It mentioned that many people who died after exploring a tomb could have inhaled toxic spores from fungi growing inside! Here's an article about one of the tombs: https://theconversation.com/toxic-fungus-from-king-tutankhamuns-tomb-yields-cancer-fighting-compounds-new-study-259706
Some of preistesses in Ancient Greece(?) were inhaling vapors from geological processes to obtain their "visions".
Sorry to say, but they don't "know[s] exhaust isn't good for you"
I learned from one of those strange death TV shows that two bakery workers in Georgia, USA were play fighting with cocoa powder in the confined space of a closet which killed them because the particulate of the cocoa dust was so fine that it clogged their lungs.
That's gotta be a particularly awful way to suffocate, and I say that as someone who loves chocolate...
If you have 4 walls and a non-zero amount of roof, you're in a confined space.
To add to this - I learned the same rule of thumb - even if you have zero roof, anything you can't breathe that's heavier than air turns that into a confined space.
aka “let’s not turn this rescue into a recovery”
Same for nitrogen and CO. CO is especially nasty bc it binds to hemoglobin and won’t let go.
I'm a refrigeration tech and I have a bottle of nitrogen in the van with me at all times. That thing gets double and triple checked every time I touch it just in case.
It gets drilled into us pretty hard just how easy it is to die when the air in your lungs is replaced by some other gas, and it's not "I can hold my breath for several minutes so a few minutes in a no oxygen environment should be enough for me to get out." Its "I just breathed out air, then breathed in nitrogen, aaand I'm out."
Yep. You can’t “tough it out” when you are passed out on the floor, dying.
I don’t think I could drive around with any source of concentrated nitrogen without the windows down.
In fairness, by opening the windows, you're only reducing the nitrogen concentration down to 78%.
That’s why at our work they would tie a rope around the welder and when he passed out they would pull him out and the next one would be sent in.
What the hell did I just read?
How is that a thing?
You need to be tied to someone on the outside that can pull you if something goes wrong, without having to enter the confined space. That part is standard. I’m doubting the legitimacy of what this person said however, implying people pass out frequently in their workplace. There are strict standards for confined spaces. I am a metal fabricator and sanitary welder and I’ve worked in some sketchy places and I’m seriously doubting a company would allow employees to lose consciousness regularly.
As someone who did oilfield safety in Northern Alberta for many years, this stuff is no joke.
No operating business would remain legally binding after having even a few incidents like that, and preferably over a much longer period of time.
Unless of course they're in a country/area that avoids such luxuries.
Or paid the president a few mil to make all those wrongful death lawsuits go away.
...in your country.
Yes…and the person appears to be from Canada or US…. which both have strict standards.
Given some of the stories I've heard, I wouldn't be surprised
It’s a thing, but it shouldn’t be the only control point. You start by making sure the atmosphere is safe or bringing in your own. The tether is then potentially for access but also to allow recovery if something happens. Like it’s a place with a potentially hazardous atmosphere so you check it and it’s safe now but you also know that it might change while a person is there. It would be difficult for them to get out as quickly as the atmosphere might change because it is a confined space so you have them wear a harness and tether so the crew outside can get them out. The actual passing out thing should be a rare occurrence, and you wouldn’t send another person in without their own air supply if someone else has already been injured. Some places have pretty lax safety standards though, so maybe it’s a thing some places.
Are you a time traveler from the Gilded Age?
No hes not. We're just getting getting a second one.
I was going to tell a good chemistry joke, but the good ones argon.
And assisted suicide pods flood the air with nitrogen. You keep breathing to put that carbon out of your blood, but when you inhale you don't get oxygen back, and eventually you go lights out. Person can still panic though, but they probably load the person up on the good stuff to avoid it in the one place you can use it or something like that. 3 kg of crushed Valium up a nostril for the most powerful of naps.
3g maybe? or 3cg.
Snorting 3kg of crushed valium will most definitely do the job.
sure, but falling down a set of stairs into a pack of rabid chihuahua with bad dental hygiene would be less painful.
Also benzos are not more bioavailable if you sniff them? Simply eat 3kg of Valium, and then fall asleep because you have put yourself into an inevitable food coma, and then die from the sedation.
Not even “generally”. The ability to detect CO2 is a readaptation of acidity chemosensors. Fish with gills just need to know to stay away from acidic water meaning it had too much CO2 dissolved in it. We are just fancy fish.
Recurrent Laryngeal Nerve fact-checks this as: TRUE!
When you think about it, all animals are a divergently evolved neotenous sponge larva. Which is probably weirder than sweaty monkey fish.
There are chemoreceptors for both, but CO2 and its effect on pH are more of the primary means of regulation. The body can sooner sense and respond to high CO2 than to (very) low O2.
This is why you can hold your breath a bit longer if you hyperventilate first (not a recommendation*). You dispel more CO2 and so that urge to inhale is delayed a bit.
I forget where I read it or heard it from but when the whole "alkaline" body craze was huge they said/wrote "If you want to know what alkaline feels like just hyperventilate. CO2 is carbonic acid, when you hyperventilate you expel more than usual, which makes your blood more alkaline."
Just drink some lye and you can stop breathing forever.
Acetazolamide
Yes. Main reason why we've had so many loses during SaR training at the army. Some went to train apnea alone, which is a terrible idea because when they did it and also used hyperventilation then there's a high chance they pass out while underwater. The reason? Hyperventilation decreases the amount of CO2 inside the lungs slightly but enough to postpone the suffocation trigger. If the O2 runs out before the need for breathing kicks in, you blackout, you drown.
Which is how my boyfriend died in 2000... While snorkeling in the Bahamas
I've seen this a lot during my snorkeling adventures. Sadly it seems common; a misplaced sense of confidence for some. Sorry for your loss.
Thank you. I learned to scuba dive afterwards to figure out what happened and to overcome my fear of the water. Turns out it's called Shallow Water Blackout and just knowing that it was a thing with a name helped a lot. I also make sure to not scrub out my CO2 before I snorkel.
Sorry to hear that. We've lost about five people that way on the past ten years. I never use hyperventilation after this happened.
Thank you. Sorry for your loss as well. More snorkeling and diving programs should talk about Shallow Water Blackout more, IMO
SaR? I'm assuming this is the same as shallow water blackout but I'm not familiar with the acronym.
There's also the issue of oxygen partial pressures, the concentration thins out as you ascend which is why it's usually a "shallow water" blackout.
Search and Rescue, but yeah, it's shallow water. I didn't take the full SaR course, just the basic one, our depth limit was over 35m. The guys who took the full course, which included helocasting, diving, swimming, climbing and bunch of other techniques have it way worse, but the diving training is basically the same, and apnea training is also the same in both.
This may sound crazy but I'm glad to know this. If I'm ever lost in open water I was planning to go under and just start breathing or something. Dying out there of dehydration or shark sounds so terrible I'd just want to go quickly
Yep. The pathway we’ve identified is that the body is actually detecting elevated CO2 concentrations in the body (hypercapnia), and the resulting decrease in blood pH (acidosis). The change in pH opens channels in the brain and triggers the feeling of panic and suffocation. Lowered oxygen isn’t directly involved in that pathway, so it can happen even if you’re getting oxygen. And respiratory acidosis can be fatal in its own right, as the study mentions.
I seem to recall a paper I read years ago describing an apparent timer attached to the diaphragm, such that not exhaling for too long also triggers feelings of panic and suffocation, even if your blood is being oxygenated and CO2 is being removed via some other means. Alas I can't even remember what decade I read it, let alone where...
Partly correct. Your body will compensate for low oxygen levels. Heart rate will go up, you'll breath faster, blood pressure will go up. Its currently pneumonia/flu/RSV season. We have a variety of machines for each person depending on what they need. It's either oxygenation or ventilation.
Your overall drive to breath isn't to get oxygen in but to get co2 out.
Source: Work in respiratory and deal with ventilators/breathing/blood gas values (pH, co2, oxygen)
Agreed. Same thing happened with my dad. His o2 levels werent incresing due to lung collapse. We tried giving oxygen but he started having side effects with no o2 increase. Then doctors suggested bipap machines to pull co2 out by forcing lungs to breath, expand and push co2 out. His o2 levels got back soon enough with no o2 supplied.
correct, usually hypoxia will just make you slowly more silly and giddy till you pass out but doesn't make you short of breath
You can actually breathe pure nitrogen and not ever realize it. You would just pass out and/or die depending on whether someone gave you a source of oxygen quickly enough.
Our atmosphere is about 78% nitrogen as it is, and about 21% oxygen. But pure nitrogen would be both unnoticeable and deadly to us. You would actually notice breathing pure oxygen long before you noticed breathing elevated levels of nitrogen.
https://www.ncbi.nlm.nih.gov/sites/books/NBK482414/
Here’s a real source
CO2 dissolved in a liquid makes it acidic, so the discomfort and pain you get when holding your breath for a long time is actually your blood turning into acid as CO2 builds up in your body.
Also, lactic acid build up from anaerobic respiration
The acidity change is nowhere near enough to trigger pain from the action of the acid. Pain from the activation of pH-gated ion channels in the brain, on the other hand...
Yes, we have chemoreceptors that detect both, but we're much more attuned to the excess CO2. The body will adjust the heart rate and respiratory rate to try and compensate and stabilize our levels.
Yep, this is why you can kill people with gases without too much pain.
This is exactly how your respiratory system works
Yes, that's why in emergency medicine, one vital sign that is closely monitored is called "end title CO2"
End tidal. As in at the end of your expulsion of your tidal volume.
Aren't there suicide capsules that just fill with N2, because you won't notice you're asphyxiating, you just feel tired, and eventually fall asleep, then die?
Nitrogen will knock you out like the Propofol to put you under during wisdom teeth extraction. It’s insanely quick, and the symptoms often go unnoticed until it’s too late.
It does but the brain - and by extension the respiratory centers of the brainstem - is far more sensitive to small deviations in [CO2] levels
A few years ago I read an article about a young firefighter who had died in training. He was able to shout “I can’t breathe!” But was disregarded until unconscious.
I read this article shortly after the death of George Floyd and it has changed how I look at some situations.
https://www.firerescue1.com/mayday/articles/respond-to-i-cant-breathe-like-its-a-mayday-because-it-is-zUGVybk27asAGiXs/
Swimmers and SCUBA divers have to learn about this.
And people who try to hold their breath through tunnels on the PA Turnpike.
Lightheaded by Ohio.
Why do they do that?
My spouse's side of the family would also put one hand on the roof of the car when driving over grate bridges.
The whole car does it. Even the driver!
Why haha? Are they holding the car up?
Some sort of superstition that I never fully understood!
To protect against witches!
Or ghost cattle..
My friend and her family used to bow her head when we went under bridges. I was a kid then, though
Because that is the correct thing to do.
Actually that doesnt help expell CO2.
When you only exhale after a long breathhold, you arent changing the composition of gasses in alveoli, and so you do not get a higher gradient difference between your pulmonary arterial blood and the alveoli (where the exchange should take place).
If we want to be very technical there are some effects of the negative pressure that you are “releasing”, which will have an effect through a reflex arc on your heart muscle contractions. Through 3-5 nerve pathways this decreases your felt “Air hunger”, some lf that being funny medullary instabilities, some of it being normal vagal/parasympathetic tone.
But no, you dont dump more CO2 by breathing out there, because that CO2 was alresdy dumped “outside” your blood (in alveoli) and what makes you dump more is the *inspired air’s lower CO2 partial pressure.
In fact… exhaling will PREVENT more gas exchange because the total reservoir in the alveoli becomes smaller and so any gas exchange which did not yet reach equillibrium is SLOWED DOWN by exhaling - until the inhalation it allows it to restart on a fresh gradient.
Huh this is interesting. I knew that the feeling comes from CO2 and that breathing out eases that feeling. What I said felt like a pretty safe assumption but I guess that's not the case.
As a physiologist, thank you for correcting this- I had to scroll a long way down to find it.
As someone who used to freedive, can you explain why the discomfort level drops and performance increases when you:
1) Fully exhale before inhaling for a breath hold 2) Exhale toward the end of your dive
Is #1 just related to decreased heart rate and #2 a way to distract your mind from the prolonged discomfort?
Learned this the direct way when I took a big inhale of dry ice fumes. Never experienced anything like that and it took a minute to recover.
Did this once as a stupid kid. Felt like someone punched me in the chest.
That is interesting. I do see that the study only examines if pressure was applied and where without looking specifically at the degree to which pressure was applied. Could there possibly be a way to ethically quantify this in a lab setting? Please clarify.
What was that comedy like 20 years ago training to go to mars and they're seeing how long they can exhale holding up a ping pong ball and the main character is kicking and flailing and hits the other astronaut
Rocketman!
Man, blast from the past, haven't seen that movie since I was a kid.
Yeah I read about this in a study done by Sebastian Fors and his team, interesting piece of work!
Swedish police is trained to know this. Its a part of their curriculum to run around and then be sat on - to show the experience. They are trained to sit on the shoulder, not the back or chest, and absolutley not the neck.
Yet 52 people during the last 30 years have died during these circumstances by Swedish police.
Not quite, the study is not limited to police. From Section 3.2:
That is a fair correction.
Great correction - I think it speaks about the efficiency of the police training.
I'm sure police did 95% of the restraints in the time period, but "just" 60% of the deaths. Making them much less likely to kill the restrained.
The police is however ultimately responsible for interventions where police officers take part even if it is together with security guards, medical staff or civilians and must take control of the situation and ensure that others such as those holding suspected offenders do not injure them and so on.
I took care of adults with mental handicaps, as part of our training they taught us about how to restrain someone safely and about positional asphyxiation. I find it hard to believe that police don't know, they just don't care.
It might be hard to believe, but it's a lot harder to safely restrain someone who is experiencing drug-induced psychosis than people with mental handicaps. Especially when it's just yourself or one other person in an uncontrolled environment Where they could have weapons or be trying to cause harm to their parties.
I have also spent quite a lot of time working with people with mental handicaps, it's a lot easier to deescalate them when you are in a controlled environment and you have 10 staffembers 30 seconds away.
I always knew this was the case, but the actual visible reality imprinted on me a month ago, when four bouncers at my place of work struggled to restrain one individual in the middle of an angry, drug-fueled psychosis.
Seeing a single man of maybe 80kg(175lbs), toss another man of well over 100kg(220+ in freedom units) over his shoulder, while standing upright, was quite the sight. Watching them trying and failing to simply handcuff this man for ten minutes really showed what the human body could do when it throws away all sense of self-preservation and pain.
I've been a bouncer in that situation before. Its even harder for us because we're not allowed to strike a suspect while they beat us back and we don't get the cop privileges of determining necessary force during an arrest because when we do it its a "Citizen's arrest". Its not uncommon for cops to arrest bouncers just cause...
That's less than 2 a year. That shows incredible restraint and training. US Cops would be laughing at that number as rookie numbers.
Comparing anything to the US will look like that.
It's 1-2 avoidable deaths per year. They still died to police brutality, no need to defend pointless deaths.
Not necessarily. In many of these cases there was no pressure applied at all by the police, and CPR was attempted. You can see it in the table if you scroll down a bit. Those deaths were probably not avoidable, and were not police brutality. It's possible for deaths to occur while still doing everything right.
The police weren't even involved in all cases.
Their population is much much less so that observation in itself doesn’t mean much…
There are more Swedes than there are New Yorkers.
How many people did the cops kill in New York in the same timeframe?
Population size is loosely comparable (~15% more Swedes). NYC cops kill about 10/year, and Swedes about 3/year in recent years. But NYC also has 3x the # homicides. Presumably higher criminality means more situations in which a police officer is justified/required to use lethal force, so comparing homicides vs deaths at police hands feels more accurate.
Or for another proxy, you might say "police are justified in using lethal force when their lives are in danger", so you would look at # officers killed in the line of duty per year (which will correlate with the number of such situations) vs deaths at police hands. In all of Sweden, the number is roughly 1 per 7 years, or 0.14/year. In NYC the number appears to be about 1.6/year, or ~11x that, which would yield "For every officer killed in Sweden, police kill 21 individuals. For every officer killed in NYC, police kill 6 individuals".
Good analysis. I like the way you explained the process and rationale used to combine data and form a more comparable statistic. It's no longer an "apples to oranges" comparison. Maybe "apples to pears" now? You mentioned a 15% population discrepancy, and others have commented on population density.
It highlights the fact that while a "per capita" comparison, especially with similar population sizes, gives more detail than raw values, it still usually doesn't tell the whole story.
However, data can be used to manipulate conclusions. I'm sure the "number of individuals killed by police" statistic could be combined with something else to flip the resultant stasticic around again.
Just in case it needs to be said explicitly: I'm not making any attempt to justify or absolve the NYPD or Swedish police of police brutality. The numbers absolutely can and should be lower.
Thanks for the kind words!
I doubt combinations of many salient variables would cause the NYC police to look worse when accounted for, because I honestly don't believe that the NYC police force is inherently ">3x as murderous" as their Swedish counterparts.
That said, your point about statistics being easy to manipulate is spot on. As seen in things like Monty Hall or Simpson's Paradox (i.e., batting averages), even very educated readers can misjudge what numbers actually tell us.
so theyre saying extreme exercise and being in a restraint position after this is what’s causing this.
seems like it’s easy enough to test.
It seems like we already know this in part. After a treadmill cardiac stress test we have to lay down flat on our backs and not move. It’s highly uncomfortable and adds to the “stress” of the test.
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man if we aren’t allowing scientists to test this in an incredibly controlled environment, why are we allowing police to do so?
its fine, they don't have scientific qualifications but they do have have qualified immunity
I mean, I get what you are saying, believe me!
This sounds exactly like the conditions in bjj and judo.
Ive passed out during competition as well. Luckily refs are trained to see it.
You would do exactly what scientists do when something isn't ethical to study in humans. Rodent studies.
Correlation between smoking and lung cancer was established in human studies, but causation was determined with rodents. Case in point.
There is absolutely a safe way to test this: you enter the scenario with monitoring equipment and end it before it becomes dangerous. There is a wide margin between "briefly uncomfortable and on the way to dying if you were to continue" and "actually dying". Like, they can and do perform tests that bring people to the edge of hypoxic brain death, because we know what the safe ranges are, where the unsafe range starts, and where the "sudden death without warning" range starts
My friends could breathe fast and press their chest against a wall and pass out. (Not safe, and we told them so). It does not take much to cause this from having seen it and it sounds similar. (Granted for my friends they were young kids and the pressure was released immediately).
purely anecdotal, but a good friend of mine died after running from the police. They caught him, restrained him, and pepper sprayed him. He was 27 years old and in good shape physically.
we definitely need to research this more for your friend and everyone else that has died from this.
It's not easy to test anything that happens rarely. 50 cases over 20 million arrest, how you test that ?
It would be difficult to test a causal effect for the reason you describe (rare population) but we could test whether the odds of dying after physical exertion are proportionally greater than the odds of dying after no physical exertion, which could be relevant.
Saw a video about this years ago. I forget the exact details, but someone who was an expert on breathing said that breathing is more expelling Co2 and not actually inhaling oxygen. I thought they said something about how we don't even really need to breathe that much to get sufficient oxygen.
Our mammal lungs are wet sacks that never empty out all the old air. They aren't that efficient, about 40%, so yeah, most of the oxygen that you breathe in goes unused. This is why CPR works, you still have lots of O2 in your lungs to give to them.
They changed standard teaching for CPR in recent years saying the breathing component was essentially useless.
Had CPR training about 2 months ago, trainer directly refuted your claim in class when someone brought it up.
My understanding is that it's because it's pretty common for the victim to throw up while the other person gives CPR, and they don't want people not doing it. That's what I was told, I used to have to keep certified on it. It does give the person oxygen, it's just not as critical as they used to think, and better to do just chest compressions than skip it entirely.
The difference is whether the course is regular CPR or healthcare provider CPR. Laypeople are no longer advised to perform rescue breathing but it is still part of provider CPR and ACLS protocols. And the main reason isn't airway protection even though that does happen. The main reason is the effectiveness of chest compressions. It takes time to build up effective perfusion pressure, and especially for laypeople every time they stop to deliver breaths perfusion drops back to zero. Because blood retains some oxygen content even during arrest, it is better to maintain constant effective compressions than to try and deliver rescue breaths with ineffective perfusion.
During my emergency first aid training a year ago my instructor claimed that the increased gas exchange is not worth the repeated pauses in compressions. Apparently blood pressure quickly drops to zero when you stop, and it then takes many compressions for it to build up again, so it’s better to only focus on the compressions until paramedics arrive
You are right, but I do want to point out that one random course teaching something does not make it a standard.
All of that said, I did find this study which mentions that including rescue breathing in CPR as a bystander led to worsened outcomes. Chest compressions are by far and away the most important aspect of CPR.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6464160/
Red Cross or AHA? Red Cross doesn’t update their information as frequently as American Heart Association. For this reason, most clinicians that are required to have a CPR card cannot use Red Cross.
While it's not as important for an adult, breaths are essential when you're giving CPR to children or babies, as well as drowning victims.
That’s just for laypeople though, because the reality is it’s quite difficult to administer effective rescue breaths while maintaining good CPR quality.
Breathing is still very much part of what medically trained people will do during full resuscitative efforts AKA ACLS.
Isn't this why CPR was changed to just chest compressions only?
I did a CPR course a few years ago for work, and they said at the time that simply doing chest compressions and no rescue breaths would still provide enough oxygen, because you're compressing and releasing the chest and lungs, which pulls in enough oxygen from that action alone.
So stopping pumping the heart to give rescue breaths wasn't the most efficient course of action.
Because people were trained to start with the breaths but the chance of survival drops rapidly the later compressions are started
I did a CPR course at work (hospital) a couple of months ago, and we were taught to give two breaths for every 30 compressions, so I guess it varies depending on your governments guidelines.
In hospital vs out of hospital guidelines. Prehospital bystander only CPR is hands only.
I saw someone say recently that the recommendation in their area was for trained people to do the rescue breaths and compressions, and random passers by on the street should just do compressions.
Apparently reluctance to give “mouth to mouth” was putting people off helping at all, either because the victim was vomiting or unclean, or they were concerned about disease and infection, or they thought they could be sued for sexual assault.
It does help, but it is like 2% survival rate increase level of help. Not worth it when you don't know the other person's medical history, would probably be worth it if it is someone you know who is healthy or if you carry one of the masks for it.
By far the most important part is getting compressions started
Rescue breathing is back in, at least as of the course I took 3 weeks ago.
Every single time I've gotten CPR training they've taught something different about the rescue breathing. Not that frequently, to be clear, but still funny.
Red Cross or AHA? Also clinician or bystander only CPR?
I did AHA CPR Heartsaver in November 2024 and rescue breaths were a part of the process.
Your memory is correct. If we just need to get oxygen we could probably breathe once per minute or less, but you can’t get rid of CO2 by breathing that slowly, and our body will trigger more rapid breathing when it senses extra CO2. It’s also why most of us breathe faster when exercising (I say most of us because elite athletes are limited by oxygen in certain cases).
This is what an asthma attack is like for me. I can inhale plenty of oxygen, I just can't get the carbon dioxide out. It's like trying to exhale through a coffee stirrer.
This description closely resembles the circumstances surrounding the death of Zak Kostopoulos, an LGBT activist and drag performer, who died after a violent encounter in central Athens, Greece, when he was violently apprehended, pinned to the ground by nine police officers, and beaten again.
In Zak Kostopoulos’ case, although the official forensic findings attribute his death to trauma-induced heart attack, the Swedish study challenges the common assumption that he died because he could not get oxygen in; instead, the lethal mechanism may be his body’s inability to rid itself of carbon dioxide under violent restraint. The Swedish review shows that in 90% of cases, where "prone restraint" (i.e. the person face down, restrained) was involved, the combination of body weight and restraint — especially prone + force — can cause cardiac arrest even in otherwise healthy individuals, due to inability to eliminate CO₂ (hypercapnia + acidosis), not necessarily hypoxia.
Interestingly, in the footage of Hellenic Police restraining Zak Kostopoulos, he was held face-down shortly before he lost consciousness, which aligns with the risk factors described in the Swedish study. It seems Zak Kostopoulos was murdered by Greek police officers...
They murdered him and then tried to paint him as a junkie who tried to rob a jewellery store.
Could this be related to anxiety tetany? I just got to experience the joy of that after my nerve blocker wore off post surgery. The pain caused a panic attack, I hyperventilated so bad that the build up of co2 caused my hands to seize up and my whole body to go numb. I was convinced I was going to die. Didn’t know it was a thing until after.
I thought hyperventilating is breathing too fast and removing too much co2, not build up. Also, sorry that happened to you!
You are correct, it is from removing too much co2, not build up. They aren’t fun, 0/10 would not recommend.
This is why you're supposed to hyper-ventilate into a paper bag so that breath back in some of that CO2 you exhaled.
Panic attacks actually cause low CO2 levels, not high CO2. This is still not ideal because it raises the PH of your blood, and your body responds to this by constricting blood vessels. This leads to numbness and tingling along with shortness of breath and dizziness.
Luckily its not dangerous and the worst thing that can happen is you pass out, which will allow your body to go back into a normal respiratory pattern and your CO2 levels will return to normal.
Passing out mid panic attack is literally just your body switching itself on and off again
Hard reset will clear a lot of problems, as long as the system wasn't in the middle of a critical process. For instance, operating a vehicle.
Wouldn’t it be “off and on again”, since you are technically already “on” during the panic attack when the “system reboots”, so to speak?
Not trying to be combative or nitpick btw! I suffer from frequent panic attacks and this is just kinda how my own brain has always viewed it. I actually used this analogy once when trying to explain it to my Dad, who spent most of his career as a computer engineer.
"have you tried to turn it off and on again"
No, your anxiety from the pain after your block wore off likely led to psychosomatic issues with your hands and body seizing/numbing. Hyperventilation is a compensatory mechanism to get rid of too much CO2. It doesn't lead to CO2 increase, it's the exact opposite. Your hyperventilation didn't start with too much CO2 unless you had other underlying issues (neurological, respiratory, cardiac). The hyperventilation was likely an expression of your panic/anxiety.
-someone who does the blocks
This guy blocks. Exactly how it was described to me after such an event.
Wow first person I have ever heard that’s also experienced it. I have 4 tetany episodes in total in my life, and yes , fingers hands, toes, feet and my tongue all went into a full cramp as I flopped on the floor and was sure that death was about to happen.
I also had no idea what it was until many years later, I did have an ambulance called each time by somebody else nearby because obviously it looks like a seizure a little bit.
Weirdly, I think I actually caused them for two different reasons on the different occasions. On day one ,I had three of the four tetany episodes. I was for certain not hyperventilating I remember just being at work and I got extreme pins and needles in my hands and it went from there. I believe I had altered my blood chemistry because I went on a two week drinking and bad diet after a break up.
Years later, the fourth time out of four that it happened I was definitely hyperventilating and that caused it as well
This exact same thing happened to me after a big hike in the middle of summer. Thought I was dying and rushed to the ER. Tests came back normal and the doctors just kind of shrugged and said, “maybe heatstroke.”
I’ve had panic attacks for over 10 years but I’ve only this symptom once, it was about 2 years ago and luckily I was at a friend’s house.
When it happened I was freaking out but he told me that it’s a panic attack, I told him this isn’t like any panic attack I’ve ever had in my life, I’m dying. He said no it'll go away within 30 mins. And it did. I was sore in my hands and calves and back for days afterwards.
He told me he gets that kind of panic attack all the time. I can’t imagine.
In confined space training we were shown videos of people who were exposed to hypoxic atmosphere for a few seconds. They were possibly seconds from death and showed absolutely zero distress, if anything were comfortable and slightly elated. Your body has no way of measuring O2, it can only detect the build up of CO2 in the blood which elicits the breath distress response.
This actually makes the whole “but they were talking so they could breathe” argument even worse, not better. If CO₂ retention is the main mechanism, people can sound “ok” right up until they crash. Curious how big the sample is and how generalizable Swedish arrest practices are.
“Talking means they can breathe” was actually originally something that healthcare professionals (at least nurses) have been taught for a looooong time, but mostly in the context of choking on foreign objects, and not as a substitute for considering other issues affecting gas exchange as a whole.
It’s not entirely wrong, but it’s oversimplified - apparently dangerously so.
If someone is talking, their airway is open enough that they are also moving air in and out, i.e. breathing. They may still not be moving enough air out to adequately expel CO2, which is obviously still a serious issue that needs to be addressed right away (and there are also so many other medical issues that can lead to CO2 building up dangerously in the body that aren’t airway-related at all).
But in a healthcare setting, there might actually be merit to distinguishing “literally can’t breathe (at all)” from “is currently breathing but still has an urgent airway problem that needs to be addressed.” It’s possible that it could be used to guide difficult decision-making in resuscitation situations (like determining if a foreign object has moved from partially blocking to fully blocking the airway or vice versa, knowing how immediately to resort to doing an invasive surgical airway, etc.).
The key is that in a medical setting, there would be professionals around who also understand that “talking = breathing” isn’t an end-all-be-all (e.g. that you can still die, quickly or slowly, of respiratory acidosis due to pneumonia/asthma/MG/drugs while still being able to talk and express your shortness of breath), as well as a focus on monitoring/treating people and the availability of equipment/personnel to address it.
In a medical setting, it will be apparent and noticed when someone goes from saying “I feel like I can’t breathe” to beginning to lose consciousness (SpO2 drops, people become less alert, etc.).
Meanwhile, cops restraining people often have them lying face-down pushed into the ground. With zero monitoring of vitals. And with ridiculously oversimplified training on respiration physiology that was never meant to apply to law enforcement settings.
“If someone can talk, they can breathe” was never meant to be taken to mean that a person’s breathing is totally fine/adequate, and especially not to justify an extended period of restraint in a position that physiologically stresses the respiratory system (performed by people who aren’t healthcare professionals who can’t even see/hear/monitor/assess the person because they have them face-down and their face shoved into the ground).
This phrasing/teaching has approximately zero appropriate place in law enforcement training for these reasons, imho - not because it’s universally wrong/useless in all professions and settings, but because it is a recipe for disaster in the hands of even well-meaning law enforcement officers.
Sadly, at this point, I think it’s going to be damn near impossible to eradicate this idea from policing given how ingrained it’s been in all first responder/first aid training and how oft repeated it is.
I appreciate people like you. I lost my head during covid and couldn’t bear to explain things like this ad nauseam
Yeah, that makes sense in the original “partial vs complete obstruction” context. The problem is it got memed into a binary safety check instead of a very narrow heuristic, then exported into a setting where restraint itself degrades ventilation and nobody has monitoring. Classic bad-systems story: a crude rule of thumb leaks out of its domain, loses all its caveats, and becomes a shield for obviously dangerous behavior.
George Floyd court case explained this
The people that needed to understand this about that case don't really care about science or reality, unfortunately. Even to this day, those people still believe you can't say anything while suffocating just because it supports their narrative. Dark times.
In the US the police and taser industry invented a fictional medical concept to explain police deaths in custody called 'excited delirium'. It's existence is widely rejected by most medical associations. It's not recognised at all in most countries outside the US.
Further study showed that most deaths attributed to excited delirium occurred in the context of inappropriate restraint by police.
I still see paramedics on /r/ems who swear excited delirium is real.
Also. You can still talk without being able to breathe in. Try it. Exhale all the air you can as hard as you can untill you cannot speak. Then, wait a few seconds and try to speak. You' be able to talk from tbe expelled CO2 in your lungs
That seems like a "distinction without difference"
The concept of "breathing" includes both inhaling and exhaling in sufficient amounts.
I mean, there’s also a misconception that if one can speak, once can breathe. This study exploring the difference helps show you can still talk while having difficulty exhaling CO2.
So the distinction seems to be that if someone can tell you they can’t breathe, you should believe them. Which cops have not always done…I think that’s why this sort of study is important even though it feels like a “distinction without difference” at first glance
It's important to publicize the difference, because their conclusion is "even though they practically were able to get enough oxygen, the cause of death was a heart attack caused by having their respiration blocked at all after high stress extreme exercise" this will inform police restraint procedures more & better than a belief that lack of air intake is causing those deaths, because it's going to be seen as dangerous to even kneel on someone's back or sternum etc if they're out of breath as well as factoring in how out of breath the person is at the time of restraint.
I admit the cynical part of me says US police won't care. But I'd prefer to think maybe people will think twice before kneeling on someone