How is respiratory failure treated?
Respiratory failure is almost always treated by placing the patient in the intensive care unit, and then as we start to administer oxygen we check blood gases. That means that we take a little needle and place it into the artery, pull off arterial blood and then analyze it for its oxygen content, its CO2 content, and also its PH. Given that information, we can tell then, quite precisely, how much oxygen to add. Or, if the CO2 is climbing, we know that we are going to have to put a tube through the mouth, down into the lungs, blow up a little cuff at the end of the tube so it seals everything off, and then supply pressure to keep the lungs open, and then flush out the CO2. CO2's concentration in the lung is directly proportional to the volume of gas that you can get down in there to flush it out. So, as it starts to climb, you have to add more and more alveolar ventilation in order to flush that out. We find that we can do a lot to correct respiratory failure, which is determined, you have to remember, by two things: oxygenation and ventilation. Ventilation is the way we control CO2, and oxygenation is where, by virtue of the fact that we add more and more oxygen, we may add completely 100% oxygen to a patient that we are having a hard time oxygenating. Bearing in mind that we are starting off at approximately 21% oxygen on room air, we can go to 30%, 40%, 50%, and keep adding as much as we need to resolve that aspect of respiratory failure; whereas, with CO2, we can add more volume, more volume, more volume, and more volume to help flush out that CO2. There are limits, and at some point in time we can start getting into lung injury by too high an oxygen content; oxygen can burn the lung, too much volume and we can pop the lung. So, it has to be done very carefully and very knowledgably, and, at times, we run out of space and we do lose the patient because the respiratory failure overwhelms even our ability to do this. Nonetheless, there is a lot to do to resolve respiratory failure.
