Alveolar Gas - Hypoxemia, A-aO2 Gradient and the PF Ratio

You cannot understand gas exchange, hypoxemia or ARDS without having a system for quantifying gas exchange abnormalities. Two systems have traditionally been used: the A-aO2 gradient and the PaO2/FiO2 ratio. While the latter is pre-eminent in clinical practice these days, an understanding of the concept of Alveolar Gas and the Alveolar Gas Equation is imperative for trainees and practitioners in Anesthesiology and Critical Care. This tutorial looks at Alveolar Gas and how the PAO2 is calculated, and it deals with the difficult topic of the Respiratory Quotient, explaining why the PACO2 is so important. I guarantee you’ll learn something.
@ccmtutorials @ortoicu
Description
00:00 Introduction and Review
00:44 Clincial Scenario – Mark, Pneumonia and Hypoxemia (ARDS)
01:38 Understanding Alveolar Gas and A-aO2 gradient
02:39 Constructing the Alveolar Gas Equation
06:33 PACO2 and the Respiratory Quotient
09:17 The Full Alveolar Gas Equation
09:44 Calculating the A-aO2 Gradient
11:25 Calculating Mark’s A-aO2 Gradient
12:45 Limitations of the Alveolar Gas Equation
14:36 The PaO2/FiO2 Ratio (PFR)
17:54 Impact of Hypercarbia on Alveolar Gas
21:59 Review