Intensive Care Network Podcasts

Basic Science Clinic by Steve Morgan & Sophie Connolly If you can’t explain it simply, you do not understand it well enough. Albert Einstein Welcome to Basic Science Clinic Raw Science episode 6. The next step on the oxygen cascade relates to the composition of alveolar gas, how and why it differs from that in the upper respiratory tract and conducting airways. This composition is determined by the components of the alveolar gas equation. We will examine the AGE in more detail in the next podcast, but for now we can take it to be PAO2 = PiO2 – PaCO2/RQ. In this conceptual model the PiO2 describes the gas entering the alveolus and the second half, the minus PaCO2/RQ, is the net gas leaving the alveolus as oxygen is exchanged with CO2 across the alveolar capillary membrane. The PAO2 is therefore the net alveolar oxygen partial pressure reflecting the interaction of these two processes. The composition of PiO2 we ascertained in the last podcast where humidification and warming of inspiratory gas at 1 atm lea