If some alveoli cease to act in gas exchange ( due to alveolar collapse or obstruction by mucus, for example), the is added to the anatomical dead space, and the sum of the nonuseful volumes is referred to as

a. alveolar dead space

b. total dead space

Explanation:

Dead space (MS) is defined as the part of ventilation that does not participate in the gas exchange. Its analysis in ventilated patients provides valuable information on the efficacy of ventilation distribution and gas exchange. Volumetric capnography (CV) or CO2 curve against exhaled volume is the most used tool for measuring MS. Recently it was demonstrated that ventilatory maneuvers of pulmonary recruitment (reversal of collapse) normalize respiratory mechanics and arterial oxygenation in anesthetized patients. The alveolar recruitment strategy not only decreases the MS but also alters the morphology of the CV curve, phenomena that are related to better distribution of ventilation and gas exchange. These findings extend to patients undergoing cardiac surgery, in which lung function is markedly impaired.