Anesthesia Knowledge Test-6 (AKT-6) Practice

The alveolar gas equation is a crucial formula in understanding the oxygen content within the alveoli of the lungs. The correct formulation is represented by PAO2 = FIO2(PB - PH2O) - PaCO2 / R.

In this equation, PAO2 stands for the partial pressure of oxygen in the alveoli, FIO2 is the fraction of inspired oxygen, PB represents the barometric pressure, PH2O is the partial pressure of water vapor which decreases the overall available pressure for oxygen, PaCO2 is the partial pressure of carbon dioxide in the arterial blood, and R is the respiratory exchange ratio, often approximated as 0.8.

The essence of this equation lies in its ability to accurately predict the oxygen concentration in the alveoli by taking into account various atmospheric and physiological factors. By using FIO2 multiplied by the difference between barometric pressure and water vapor pressure, it adjusts for the dilution effect that water vapor has in the conducting airways. The subtraction of PaCO2 divided by R reflects the balance of carbon dioxide removal and oxygen uptake, ensuring that the equation reflects the dynamic equilibrium within the respiratory system.

The intricacies of this equation aid healthcare professionals in assessing the adequacy of ventilation and gas