Figure 2
From: Carbon dioxide kinetics and capnography during critical care
Effect of alveolar dead space (VDalv). The right lung compartment receives no perfusion and contains no carbon dioxide (ignoring interlung unit ventilation). By mass balance for carbon dioxide, VDalv/VTalv = (PaCO2 - PETCO2)/PaCO2. For the sample condition shown, VDalv/VTalv = (40-20)/40= 50%. PaCO2, arterial PCO2; PACO2, alveolar PCO2; PETCO2, end-tidal PCO2; P
CO2, mixed venous PCO2;VTalv, alveolar tidal volume. Adapted from Breen [61].