Quote from [this article in the Washington Post](https://www.washingtonpost.com/opinions/2020/04/09/my-near-death-experience-ventilator/), from a person who spent 6 days on a ventilator:
> For me, my lungs must rebuild their capacity. I experience breathlessness from even mild exertion. I used to run marathons; now I can’t walk across a room or up a flight of stairs without getting winded. I can’t go around the block for fresh air unless my husband pushes me in a wheelchair. When I shower, I can’t stand the entire time; I take breaks from standing to sit down on a plastic stool I have placed inside my bathtub.
> Being on the ventilator for almost a week damaged my vocal cords, and now my voice is extremely hoarse. My speech pathologist expressed optimism that the damage is not permanent. Only time will tell.
Honestly though, I prefer a more scientific explanation than a real ELI5. I would have posted on AskReddit but they don’t allow adding context in a text post as I did here.
In: Biology
The reason why people need to be on ventilators is because the virus and body reaction to the virus destroyed parts of the lung. The ventilator didn’t do the damage, the virus and body reaction did.
They don’t lose fitness so much as their lungs haven’t regained the ability to absorb the oxygen fully due to the damage from the virus. Sometimes those scars are permanent.
Vocal cords get injured by junk being pushed down the throat.
Also, being on a ventilator for a longer period of time (15+ days) can over-expand the lungs. This can also cause issues.
A tangential issue to what you are asking is how quickly muscles atrophy from disuse. I was in an ICU for 3 days on so much morphine I practically slept the whole time. My first day of physical therapy when I got to a regular room was to sit upright for 30 minutes. Day 2 was to walk across the hall with a walker; I passed out after 10 feet.
Don’t forget that by laying in a bed you lose 15% of your muscle mass *per week*. Use it or lose it is very real. You don’t need to lose a lot of muscle mass before you can’t even stand up.
Your lungs are a vital part of your entire system and when they are full of gunk or scarred the hell from an illness they can no longer work the way that they used to work.
The muscles that allow you to breath are working 24/7 for your entire life without taking a break. When you are sick enough to need to be placed on a ventilator, these muscles don’t have to work so diligently and begin to weaken immediately – sometimes a loss of 50% of their strength within 16 hours of ventilation. It can be very hard to stop ventilators because patients tire quickly just from the effort of breathing and need to be weaned off ventilator support slowly over several days.
Ventilators force air into the lungs with positive pressure rather than the chest muscles and diaphragm pulling air into the lungs with negative pressure. Imagine blowing up a balloon and letting the pressure from the blown up balloon back into your lungs – it’s uncomfortable and can cause damage by overinflating or underinflating the delicate lung tissue.
I spent 8 weeks in ICU in the UK in a coma and on a ventilator a few years ago. Pneumonia usually comes hand in hand with being ventilated due to fluids falling down the open airway. The pneumonia was far worse than the original reason for the coma and has left permanent scarring on my lungs meaning my lung tidal capacity is reduced. Muscle wastage is rapid whilst being in a coma. The wake up process took a week with terrible hallucinations. I wasn’t even able to lift my hands off the bed for a few days and it took months to be able to walk unaided again. Pneumonia is so hard hitting though. It take antibiotics and intensive bedside physio just to get the junk that fills your lungs out. I was told by the ICU nurses that it is very dependant on how long you are on a ventilator for as to what lang term or permanent damage it does.
Mechanical ventilation is a positive pressure system. Normally we breath using negative pressure and small muscles we are not even aware of.
When you are sedated and the ventilator breathes for you, your breathing accessory muscles atrophy rapidly, (along with the rest of your muscles) from lack of use.
Complications such as COPD, pneumonia, shunts, or fibrotic tissue can significantly prolong recovery to baseline.
Source: ICU RN & Transplant Coordinator
It isn’t just the damage to the lungs from the disease or its affects, or even from the ventilator itself. There is also evidence (like most stuff with COVID this is still preliminary and is being vetted by other experts)now that COVID is attacking the hemoglobin (oxygen carrying part of red blood cells) and reducing your blood ability to carry oxygen. So what is happening in some cases is the lungs are actually working fairly well, but the oxygen exchange is broken down.
All of this boils down to hypoxia, or a lack of oxygen in your body. Same thing a high altitude climber or a pilot gets without oxygen is going on in COVID patients, the issue is the cause. In something like high altitude, you just need more oxygen in the lungs. In pneumonia, the lungs capacity is offset by fluid so only a small percentage is getting air with oxygen and moving that oxygen to the blood. With COVID, the air is in the lungs, but blood isn’t picking up the oxygen. That is possibly why the ventilators aren’t making as big of an impact as expected. However, ECMO is showing signs of being a good treatment as it does reoxiginate the blood.
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