How Far Can We Push the Human Body? - with Dr Rohin Francis

Human bodies are remarkably resilient and capable of incredible feats in the most inhospitable of environments.
Subscribe to Rohin's channel: / medlifecrisis
Watch the Q&A: • Q&A: How Far Can We Pu...
Modern medicine has blurred the lines between life and death, and is showing no signs of stopping. Rohin explores how humans are pushing their bodies further than ever before, in sickness and in health.
Dr Rohin Francis is a cardiologist in the UK. He trained in London and Cambridge and he is currently undertaking a PhD at University College London. He makes KZbin videos concentrating on topics that don't get covered elsewhere like offbeat science, understanding why modern medicine doesn't always work, or forgotten chapters of history.
This talk was recorded on 26 January 2021.
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[@MedlifeCrisis]

Thanks for inviting me! Hope I can visit in person some day. To those unhappy with the low resolution video - I really do apologise. The camera is actually fantastic, my face is just 240p in real life.

[@chandrakantsharda3525]

I was literally waiting for your piece so that i can unsubscribe from this channel. I am quite addicted to your content.

[@zachwatson4377]

You look truly crazed on the thumbnail. Love your vids!

[@frogz]

your face is awesome in 320 by 240, dont listen to the haters!

[@Howtard]

The saving grace was putting you into a box that was appropriately small for the resolution of your face; once you were banished to the corner, it was a nonissue

[@israel963]

You should really talk to The Architect about that. Are you stuck on an old firmware?

[@TheRoyalInstitution]

We are beyond excited to have had our friend @medlifecrisis over for a talk about the extremes that we can push the human body to. Also check out the Q&A where Rohin answers questions about resting heart rates, the Denisovans and what is the best medschool in the UK. And if you are left wanting more, subscribe to Rohin's channel right here on KZbin - kzbin.info

[@nikelinderoth1809]

Thank you for this! Where can I find the Q&A?

[@pipp972]

"The human race wouldn't be where we are today without our ancestors pushing their boundaries" I can't believe Francis is a lamarckist

[@MedlifeCrisis]

My parents pushed their limits so hard that I was born with a pre-pushed limit and if I keep pushing, my son will be limitless. It's just basic science.

[@nHans]

@@MedlifeCrisis Or you could feed him NZT-48. It's just advanced science. Much simpler.

[@bryanjackson8917]

Doesn't mean he is a Lamarkist at all. If a species, for whatever reason, "pushes" its boundaries into new environment ("econiche"), then obviously those members of the species that were already better suited physiologically/genetically to survive in that econiche (i.e., "pre-adapted") will leave behind more offspring which will share that pre-adaptation. Simple application of principles of natural selection as first enunciated by Darwin himself.

[@hy7968]

@@MedlifeCrisis 69 likes

[@lenyekpenyek]

As a doctor myself, hearing stories of "I can't believe this patient survived with (parameter) of (mindblowing numbers)"from my ED colleagues are always interesting

[@nodriveknowitall702]

As some nobody from nowhere, I also find it intriguing.

[@emilychb6621]

Back when I did civil service, I brought a patient to X-ray, with a blood sugar of 18. And she was reasonably conscious, until the ER came running with the crash cart and glucose bags because the nurse student that had taken the blood sugar had finally come around to entering the value in the files, and someone else noticed the red value.. o.O

[@emilychb6621]

Which also reminds of of the surprisingly large number of heart attack patients that would sneak out of bed for one last wee, return to their beds and then die...often that ended up being the corner of the room, since the crash rooms didn't have their own ensuite toilets...

[@etherdog]

Dr Francis is not only immensely informative but also full of humorous asides. His MedLife channel is equally so. Props to the Star Trek background!

[@valeriavagapova]

This was SO interesting, I started listening thinking I would finish later and just couldn't stop. Dr.Francis is perhaps one of the most engaging speakers I've ever heard. Thank you so much!

[@deadbzeus]

What a great presentation, always love hearing someone who is passionate about a subject speak on it. Hope you have him back again sometime.

[@transkryption]

A side hustle as a DS9 cardiologist... I love you Dr Bashir!

[@curiousfirely]

Thank you for joining us from the Medical Bay!

[@MBkufel]

Hats off to everyone who just keeps up CPR for 4 HOURS (78 minutes is also a good amount of time). These people are real titans of physical fitness and mental strength. I really cant even imagine what it takes to just keep going for more than 20 minutes.

[@wojciechsikora3497]

Prolonged CPR, especially in cases such as drownings are usually managed by devices such as LUCAS. Machine will always be more consistent than a team of tired people.

[@SIC66SIC66]

I got a spontaneous collapsed lung (pneuma thorax) once, but it was wrongly diagnosed by the GP as something to do with the muscles between my ribs. In the 8 years after that I suffered probably 40-50 more ( maybe partial) collapsed lungs but always assumed it was the ribs playing up again. Until one day it was so bad I had to go to the hospital. I just walked in with 1 fully and one partial collapsed lung, yet my oxygen saturation was still at 97%. I got some very surprised looks from the staff at the hospital. Could it be that over the years my body adjusted to coop with a limited function of my lungs??

[@kattenmosart]

Have you been diving? Someone had to bail out from a 100m dive and was still at 40 m when at sea level and still survived living with pneuma thorax 10 years later , this should been impossible but happened anyway. Didn`t know that about 50 % of the lung capacity was gone.Still had 80% capacity CO2 in test.

[@rdizzy1]

Was the incorrect diagnosis costochondritis? Just wondering.

[@rdizzy1]

@@kattenmosart I would imagine it would be possible with long periods of heavy forced breathing for the other lung to expand (as it is an air sac afterall),making up some of the difference, much like the stomach sizes of extremely obese individuals (some can have a stomach that is 4x the size of a normal individuals stomach)

[@MrQurutin]

This is just anecdotal stuff from your regular nurse but I work at a cardiothoracic surgery unit and regularly see patients with pneumothorax or even pneumo+hemothorax (blood in pleural space) with perfectly normal oxygen saturation levels or dipping just below that. Especially on young and relatively healthy patients, for example trauma patients from road accidents or falls or so, at rest partial lung capacity can deliver enough oxygen and body can compensate with rapid breathing for lack of capacity for proper pulmonary ventilation (oxygen in, carbon dioxide out). Person can very well function with only one lung after all, although I'm sure body will compensate for that in one way or another in the long run, but I would probably say it's not really that abnormal, but that of course depends how severe your pneumothorax was.

[@5thearth]

Re: CO2 in the bloodstream being the trigger for the breathing reflex, this is why inert gas asphyxiation is so dangerous. If you breath, for example, pure nitrogen, your body will have no problem expelling CO2, and so you won't feel any discomfort. But the lack of oxygen will quickly impair your thinking to the point you can't recognize the danger, and then you abruptly pass out and suffocate without ever noticing anything was wrong.

[@Saezimmerman]

Tragically, this has killed both the initial person exposed, and the people that try to rescue them.

[@AelwynMr]

Yep, same with carbon monoxide, only that is actually poisonous, in that it binds to haemoglobin so much better than oxygen that you don't even need to remove it from the air you breathe to suffocate!

[@gasdive]

Speaking of the body working around long term issues... I had bad asthma as a kid. I now trigger breathing both from low O2 as well as high CO2. I can tell when I'm breathing low O2 gas. It feels horrible.

[@AelwynMr]

@@gasdive When does this occur? I can't really think of any situation where oxygen would be low, other than high altitude 🤔

[@gasdive]

@@AelwynMr high altitude is one. I pant like crazy. It dries out my throat. I also have super high respiration rate on a rebreather if the O2 is low. At 6% oxygen I get a feeling of doom. Not sure how else to describe it. But also, I stop breathing if I'm breathing pure oxygen, particularly under pressure. I breathe if I'm thinking about it, but I've had friends watching me and I drop to about one breath a minute breathing pure oxygen at 2 bar.

[@damongreen6433]

scuba instructor of many years here - loved everything you had to say, with a personal bias towards the underwater bits in particular :D

[@GLOKD]

Dr. Rohin Francis is a brilliant educator. Plz book him in the Faraday Theatre.

[@visitor55555]

Wooow, cool. Again, I hope you and your colleagues know how much you're all valued and appreciated.

[@ChavaLeEtranger]

and by colleagues you obviously mean other KZbinRS, right? =P

[@visitor55555]

@@ChavaLeEtranger I'm not sure what you're implying but I mean other medical youtubers yes but mostly frontline medical staff.

[@mallorymyers7525]

You're in sick bay! Best background 🏆

[@richard_d_bird]

"if you push something hard enough, it will fall over"

[@ontheballcity71]

I am a scuba diver. I had a hole in my heart, (an ASD), which caused a bend. I had surgery to close the hole in December, so should get back to full diving soon.

[@aussieevonne7857]

Great talk, Dr F. I like hearing you talk about this topic (biological tolerance for extremes). I like hearing you talking about many other topics too. Thanks for linking here from your YT channel thingy.

[@em_pen]

Yay glad this made it to KZbin, thanks! Rohin is amazing, but obviously he was too busy to do this one and just sent his ghost.

[@henrygingercat]

Brilliant as ever. Where on earth do you find the time and energy?

[@blooksyaha1531]

Work isn't work if you're having fun

[@chrinarai]

Probably something like: - great airways so no sleep disordered breathing issues - robust genetics in terms of managing oxidative stress, neurotransmitter levels, and general immune system balance

[@lemueljohnurbano3705]

I like how this guy delivers such an interesting topic!

[@darkwinter6028]

Dang the bitrate sure got squashed on this one... we should start a grassroots movement: broadband for doctors... ‘cuz getting what they’re saying is >important< !!1!

[@bobwright8778]

I am always blown away and so relieved that there are human beings with a burning intelligence, a seemingly huge capacity for learning and continued fascination with the world. Me? I'll make the tea and listen

[@pstewart5443]

Nutrition has come a long way as well race or event management. When you see a leap in the understanding of nutrition, technology, and training methods there is also a complimentary change in outcome of performance. Had ancient athletes had our access to these improvements, then they would've probably outperformed today's athletes considering their performance without all of these advantages. Also, when one considers the factor of evolutionary biology; the mating and product of super-athletes today, we see an even greater leap in their offspring. At this rate and the world's population we may see performances we currently believe impossible. As a former Ironman triathlete, I have seen some pretty unreal performances over the past two decades. When we then look at PEDs we may see super-human level results. I had my resting heartrate down into the high 40s in my early 20s. I was running, lifting weights, playing hockey, and running with a 35lb rucksack as part of my military service. I was diagnosed with sinus bradycardia due to this. I was 6'6" and weighed around 190lbs. I often was dizzy upon standing, even slowly.

[@rhosllwyd2863]

Enjoyed this and learned. Especially liked the tangents!

[@binaryalgorithm]

As someone with asthma who gets winded easily... the human body is still amazing.

[@LeoStaley]

I'm just here following the master of memes

[@Reticulosis]

I can’t believe I just found this! This was awesome, totally worth the hour of procrastination vs doing my research paper 👏

[@racekarts]

As a former extreme athlete and distance diver, this vid was excellent, and just like most of your other videos also brilliant and very entertaining 👍

[@valentyn.kostiuk]

Поразительные случаи и правда!

[@mrwideboy]

The sherpa and people from tibet have a gene from the Desvonians ( similar to the neatherthals ) which gives them that advantage to live at height

[@rolfs2165]

*Denisovans ;)

[@meretriciousinsolent]

I once overtrained for a 10k and gave myself anaemia (I was eating terribly, not supplementing, my own fault) and had blood iron level of 10 - I always wondered what that actually meant, so thanks for that. It was the oddest feeling, I would run and general fitness would keep me afloat but it was like having one of those restrictors on a car - there was just a palpable wall that I couldn't pass. I ran the 10k though!

[@fa2589]

I wish all my lectures were half as interesting 😍😍 also those first three slides... it took me three whole days just to understand it 😨

[@DuncaR]

@12:00 what was the output of the 2 pumps? You mentioned average at rest is about 5L/min?

[@rdizzy1]

I've had severe high blood pressure ever since I was 14 years old, in the early years (at around age 16 and I was very thin, athletic and fit), my average bp was about 200/110 pretty consistently, and my resting heart rate was also about 120 bpm, and I am in my late 30s now and they still haven't found a cause, have been on 4x the average dosage of 4 different drugs in combination just to keep it at about 150/90 on average. This video, as well as variation in humans is very interesting.

[@TheyCallMeNewb]

Mordant sense of humour in this one. A richly beneficial divertissement was this lecture.

[@sirknowitall123]

I really enjoyed this and you have great communication skills.

[@Im0nJupiter]

Your kids sound so cute! Monsters surely, but cute!

[@devekhande9204]

Depends upon who is pushing.

[@Sebastian-oo7xi]

At 40:00 you say something like "your total body-blood-volume is around 40 L" before that you said " the flowing blood is about 4 to 5L" So I assume you meant bodyfluid? Can you help me there? I know, talking for 1 hour, there happen little mistakes. Anyway, greatly appreciated and it is astonishing that he could loose 16 Liters! Just mind-blowing.

[@Erin-hq2bz]

I think he misspoke - normal total body water is about 42L (in cells, tissues and blood) and normal total blood volume (water snd blood cells) is 4-5L. The cyclist required 17L of IV fluid demonstrating he was severely deplete in water throughout his body (extra and intravascularly)

[@leoniegrosse9121]

Great talk, very interesting! Motivates me to get back to studying for my physiology exam

[@julianatlas5172]

Are you in the enterprise? That is awesome

[@MedlifeCrisis]

Voyager! I'm more EMH than Dr Crusher. I'm even more Julian Bashir than either of them but DS9's sick bay was hard to find!

[@julianatlas5172]

@@MedlifeCrisis I like Julian Bashir as well! We share our name after all 😁

[@user-vn7ce5ig1z]

@@MedlifeCrisis Who's your Garak? 🤔

[@meretriciousinsolent]

I could never quite figure out who Bashir was supposed to be. The EMH had more of a personality, I thought.

[@HianDenka]

I burst out laughing at the Teenagers are unbreakable line, i agree, humans are literal werewolves at that age nothing can stop them. i rmbr treating my body like absolute dogshit and being able to scale a mountain the next day on like what 15 mins of sleep through 3 days. too good. i miss that energy

[@t0piel]

Hyperventilation doesn't really extend your breath hold (exercise does), instead it extends the "pleasurable" part of it, making it seemingly longer. Controlled abnormal ventilation is probably more of a use here. Hyperventilation while diving out at see or in a lake is a big no no, cause it makes you susceptible to the illusion of being totally alright while your body is struggling in fact.

[@LadyPelikan]

I have a question about de oxygen pressure of 3 kPa in people climbing the Himalayas: How important is the absolute number, and how important is the relative difference, when comparing the oxygen pressure in the blood with the surrounding oxygen pressure (which is also much lower than normal)? I'd guess Boyle's law plays a role, no?

[@vlastneme]

Star Trek sick bay, love:)

[@t0piel]

And to rain some more on your parade, the deepest freediving attempt atm, awarded with a world record is actually 130 meters - Alexey Molchanov, 2018, monofin (CWT discipline). Pool competitions at world-class level are fun too - 300-meters run there and back again.

[@LeoStaley]

Does anybody know how to clean up the audio here, if I were to download this video?

[@isla25]

Brilliant as ever, thanks Dr. Francis

[@BishopsBee]

❤️

[@krigarb]

5 minute lead up to the "hard' part .. Shows 3 emojies

[@mrki83]

Freedivers can get decompression sickness - Herbert Nitsch, the holder of the 214m world record, got badly hurt on his 253m record attempt.

[@DuncaR]

@33:00 what does induced mean in this context? The hypothermia was deliberately brought on?

[@JKenny44]

Yes. It seems to be. He talks a little bit afterwards about patients with cardiac arrest being brought to a low temperature to reduce neurological trauma. Seems to be very new and poorly understood method from the way he describes it. I've never heard of it before.

[@ignorasmus]

Who else here wants to see a bunch of Bajau people and Sherpas to hook up and see what kind of super humans they create together...?

[@katrindanevova1232]

37:04 normal haemoglobin is 140g/l or 14g/dl ....how did they measure arterial oxygen in the mountains? Cause one would need some fancy stuff no?

[@tactileslut]

My guess: store the sample and test it later. Even easier: bring a clip on oximeter. They're neither large nor heavy.

[@TesterAnimal1]

They could well have had the equipment. Lots of climbers are doctors.... or the other way round.

[@katrindanevova1232]

@@tactileslut sry, yes ur right, under normal conditions/atmospheric pressure that would be possible when the oxygen dissociation would follow the oxygen dissociation curve you could calculate the partial pressure of oxygen (&approximate the oxygen content of blood) from the oxyhemoglobin 02saturated hemoglobin ....however spo2 - measured by standard pulsoxi - does not take into account some weird stuff like carboxyhemoglobin or methemoglobin - normally less than 5% of normal blood - and also other parameters which change o2 affinity for oxygen, like Co2 concentration or ph, which can be measured by arterial blood gas analysis. Normally the partial pressure of oxygen in ambient air is around 160mmhg - around 21kpa and in our arterial blood its around 90-100mmhg or 12-13.3 kpa, which gives us a sp02 of 95-100 percent, however the affinity of our hemoglobin to o2 decreases as the partial pressure gets lower, which is necessery for o2 to be delivered to our tissue where partial pressure is about 40mmhg or 5.3kpa and the oxygen saturation would dropp to btw 50-60% in such high altitudes thus we would expect our hemoglobin to have a much lower affinity and saturation and our total o2 content to be decreased, however in the climbers of the study it wasnt the case their oxygen content dropped down just about a quarter despite the partial pressure of o2 being about 20mmhg or 3kpa ... which is below the o2 partial pressure we have in our veins normally ...and yes again u were right they stored the samples taken at the peak and measured the blood gases at a base a little below

[@jumpkeeable]

Love the talk. Thank you

[@baptistemassart1440]

Very interesting, many thanks!

[@StudyWaliClass]

so great very informative awesome superb

[@BryonStice]

When I had pneumonia my temperature got above 41*c and I was having hallucinations. Not pleasant.

[@tisFrancesfault]

I don't think I can follow this; those slides were pretty complex.

[@PedanticNo1]

Blame France

[@warbler1984]

@@PedanticNo1 you blame Dr Francis instead

[@elinope4745]

Can we make it so they could survive in a 20 percent methane atmosphere with average temperatures 15 degrees Celsius higher than now?

[@Saezimmerman]

Fascinating topic!

[@mokobaby6181]

Whose medbay is he in? I'm leaning towards voyagers, but not sure

[@user-vn7ce5ig1z]

He said Voyager (but he would have preferred DS9 if he could have found a photo).

[@Thoughmuchistaken]

An altogether excellent EMH.

[@thomasjwynn]

Great talk

[@MrPinknumber]

Love this guy !

[@kagannasuhbeyoglu]

👍

[@adhipmitra]

Very enlightening and interesting.

[@ilyarepin9490]

ROHIN ROHIN ROHIN

[@ez3748]

more of this please!!!

[@ashurean]

Sometimes the body just decides to not care about how lethal the numbers are and makes the executive decision to continue living anyway.

[@Mkjackary]

Nice

[@PrimeMatt]

Great video

[@wktodd]

Interesting thanks

[@kisnpisn4919]

now this is a worthy thumbnail

[@stephenconnolly3018]

Is he on the Star ship enterprise ?

[@b.griffin317]

How do marine mammals like whales avoid the benz when they make epically deep dives?

[@TesterAnimal1]

“The bends” is the colloquial name for it.

[@Brett_S_420]

Naturural selection 🔁 Adaptation × generations of lives = No bends.

[@b.griffin317]

For the record neither of these replies was helpful.

[@selfcensorship1]

After your kanabis video I needed a reminder to why am I subscribed, and here it is. BTW, I was not a staunch opponent of legalization, but it was boring and very not convincing. Is this feedback positive?

[@sliekens007]

28:02 why is the brain more sensitive to lack of oxygen than other organs? It's not clear from the context.

[@TheRealSlimLeif]

The short version is this: The brain requires a lot of energy to function. The process of making this energy requires lots of oxygen. When oxygen levels fall too low for too long, energy is depleted and neural cells within the brain begin to die. And since the neural tissue has a very limited ability to repair itself, this damage is often permanent. The brain can, as other organs, make use of anaerobic metabolism. This is far less efficient than using oxygen and while it can sustain other less energy hungry organs for short periods of time, its effect on the brain is quite limited and used only as a last resort.

[@liangliangsusan]

Bruhhhhhhhhh

[@simppuful]

Then like the opposite, how high can we lift another person. We human are sadistic, narssisstic, wvilm apes.If we give something good to another, we hold out our hand to got something more in return. If we do harm to another, we ask for forgiving, or we repay with some excuise and a rose. Isnt that alarming.

[@muff10000]

Now you talking to someone that have had 42+ that lasted for days with other extreme values at the same time and still lives 26 years after that ;)

[@rajeevgangal542]

The habitable zone is part of business plan touted by Google's lifescience company: verily

[@simppuful]

Is it own choises?

[@christienjanson6530]

Sherpa have Donisovan genes!

[@sayakdasgupta8905]

That American unit bit😂 “no civilised country should understand “😂😂😂

[@claytonreardon42069]

Algorithm comment

[@gabirican4813]

" blurred the lines between life and death"?

[@rickblane6784]

wasn das-

[@simppuful]

The narssisstic will to control another.

[@austincolenutt]

KOTOR

[@AelwynMr]

HERCEG NOVI

[@GLOKD]

@6.20 Also iq. Hehe.

[@suchistheuniverse7858]

38:53 Why do we have here photo w/out all his footwear visible? Maybe footware is too unconventional, maybe photographer was inexperienced, what is your opinion?

[@wolfensus]

about 5 miles

[@user-vn7ce5ig1z]

• The R.I. now has comedians give talks? How far this once-respectable institution has fallen. 🤦 And of all comedians, they pick one who has never even told a joke in his life. ¬_¬ I'm just disappointed the holographic Doctor (or at least Dr. Crusher) didn't walk by in the background in the med-bay. 😕 (Rohin should have sent the kids to play in the holodeck.) • 44:22 - Oh, snap. Throwing shade at the anti-Metrics. | • 53:35 - They've also adapted to seeing clearly underwater.

[@MedlifeCrisis]

The seeing underwater isn't an adaptation, and it's not the Bajau, that's been observed with the Moken. It's simply something learnt from a young age, not a genetic adaptation. Anyone can achieve this if they dive from childhood and train themselves, unlike the changes seen in the Bajau.

[@lisaschuster9187]

37* Celsius is only 98.6* Fahrenheit. F makes much smaller, handier leaps, and 100*F (about 38*C) in the afternoon is not a fever. You can’t fool North Americans with slippery statistics, Doc. (Narrow range, indeed!) 🤓

[@KGatLC]

You left out the lungs of freedivers.

[@SuperOptiman]

I wish you would’ve had a better microphone so that I could understand what you were saying. Intelligibility to these 70 year old ears was terrible. I had to stop listening and watching. Darn! I always enjoy your words of wisdom.

[@kevinbreslin5718]

No way there has been a billion years! Much less the first billion?

[@TesterAnimal1]

? The universe is about 14 billion years old.