Alveolar dead space, physiology space11/14/2023 ![]() Bohr equation determines the physiologic dead space: V D V T x (PaCO 2 - PeCO 2) /(PaCO 2) In a healthy lung, V D equals the anatomic dead space (normal value: approx. Hopefully the components of that volume of air will be clearer after reviewing the following illustrations. Alveolar dead space: the sum of the volumes of alveoli that do not participate in gas exchange (mainly apex of the lungs) These alveoli are ventilated but not perfused. And then real quick before we dive in: if you’re not familiar with the idea of dead space in general, it’s the concept that there is a difference between the quantity of air breathed in during a breath (tidal volume) and the volume of air that actually participates in gas exchange at the alveolar level (clinically relevant tidal volume). Alveolar dead space is typically negligible in a healthy adult. ![]() ![]() Dead space is a concept that we generally discuss in the context of mechanical ventilation – this short series of graphics won’t get into too much detail on that, but we can point you towards our free book on the idea: The goal here is simply to review the different types of dead space, demonstrate them graphically, and point out specific interventions for each of the various types. We examined the influence of three variables (different breathing circuits, breath selected for analysis, and alveolar dead space ventilation) on the accuracy of noninvasive cardiac output determinations with the Fick CO2 (indirect) equation. ![]() The series of illustrations in this post demonstrate the different types of dead space encountered in clinical practice and interventions to address them. ![]()
0 Comments
Leave a Reply.AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |