Respiratory failure is failure of the respiratory system to do its job properly. The job of the respiratory system is to add oxygen into the blood and remove carbon dioxide. Failure of either one of these, manifesting as low oxygen in the blood (hypoxia) and high carbon dioxide in the blood (hypercapnia) respectively, constitutes respiratory failure. Of the two respiratory gases oxygen level in the blood is the more fragile. Loss of function of a relatively small portion of lung tissue, for instance due to a localised pneumonia or a PE can result in a radical drop in blood oxygen level. Meanwhile carbon dioxide level is unlikely to be significantly altered if only a small portion of lung is non-functional. This type of respiratory failure in which oxygen is low but carbon dioxide remains within the normal range is called type 1 respiratory failure and typically arises from a localised disfunction of lung tissue rather than a globalised respiratory system disfunction.
In contrast Type 2 respiratory failure is when carbon dioxide level is too high within the blood. For this to occur it typically requires widespread disfunction of all of the lung tissue or at least the vast majority of it. It is a more severe form of respiratory failure and is typically much more difficult to treat than type 1 respiratory failure which can be treated by putting the patient on oxygen (i.e. raising the FiO2) until the disease process causing the disfunction has resolved. Conditions such as widespread pneumonia, interstitial lung disease, asthma and COPD can cause type 2 respiratory failure as they cause widespread disfunction of all of the lung tissue.
In this video I discuss how type 1 and type 2 respiratory failure are diagnosed and how they are treated. I also discuss examples of respiratory conditions which can lead to respiratory failure and explain in detail how they lead to the respective types.
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