How is mechanical ventilation actually helpful if the diaphragm is working normally?

Question

Mechanical ventilation appears (to me, a naive observer) to help only push air into the lungs if a person cannot breathe well— that is to say, having difficulty inhaling and exhaling. It makes sense to me that a person who is perhaps paralyzed would need a machine to force the lungs the work, mechanically speaking.

But how does this help someone suffering from injury or disease in the lungs themselves? Is a ventilator better at delivering oxygen than our own normal breathing process?

In: 8

Answer 1

>Mechanical ventilation appears (to me, a naive observer) to help only push air into the lungs

You are correct. Normal lung use is sucking air in. This is the active part of normal breathing and requires energy. Energy requires oxygen. Keep this in mind.

Air coming out is passive. Our system returns to normal or relaxes.

Pressure likes to be equal. So when the lungs expand it creates negative pressure inside the body and outside air goes in to equalize.

The ventilator is a positive pressure system. Your body requires no extra energy to move the respiratory muscles around.

>But how does this help someone suffering from injury or disease in the lungs themselves?

Many ways. One in particular is shock. The most basic definition is low oxygen to the cells, the reasons are many. So if you’re in shock and need more oxygen a simple way for us to reduce consumption is to stop the muscles from burning it or more of it. Regardless of how well the diaphragm works seeing as we can’t stop say.. The heart.

Say the body needs exactly 100 oxygens to function.
Those 100 are split up by all the different systems with some left over. Let’s say suddenly the body is no longer able to deliver those 100 oxygen because it lost half of your blood. Now you only have 50 oxygens but the rest of your body is fine and still needs its reserved number. If we remove (paralyze) the respiratory system (diaphragm too) the required oxygens is now less. All the other systems get more available oxygens.

>Is a ventilator better at delivering oxygen than our own normal breathing process?

In a normal healthy person, no.