How does being on a ventilator cause someone on it to have organ damage? I thought ventilators are just supposed to help you breathe?
In: Biology
Ventilators force a certain quantity of air into your lungs (tidal volume). In healthy lungs, as long as the tidal volume isn’t too high, then the air distributes itself pretty evenly throughout the lungs. You can also use quite low pressures to push the air in. A coma patient with healthy lungs may be fine on a ventilator for a very long time.
However when sick, some areas of the lungs may become gummed up with mucus or inflamed – when this happens the air doesn’t flow as easily into these areas. This can cause the remaining healthy areas to get stretched since the air forced in flows preferentially to these healthier areas. This causes damage over time. In addition you may have to increase the inflation pressure to try and push the required volume of air in, which has a similar damaging effect.
It’s a balancing act, you can generally turn up oxygen to help get more oxygen into the blood if a patient is struggling – however its difficult to turn up the rate that carbon dioxide leaves the blood. You can either increase the tidal volume, or increase the breathing rate – however a faster breathing rate means that there is less time for carbon dioxide and oxygen to diffuse out and you may need to use higher pressure. At some point the patient can become so ill that you simply have to turn up the tidal volume to stop carbon dioxide buildup, and this can cause damage.
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