An alternative is the Hatch 7 or Langley 8 method in which a straight line is fitted to the most linear part of the expired CO 2 volume ( V eco 2) vs expired volume ( V E) curve by linear regression. 4 Anatomical dead space is thus important because the measurement of alveolar dead space depends on the accurate measurement of anatomical dead space.Īnatomical dead space is commonly calculated by the Fowler equal area method, 6 which uses the expired CO 2 concentration or partial pressure vs expired volume curve.

Alveolar dead space is calculated as the difference between physiological dead space ( V d phys) and anatomical dead space, 5 and can be affected by changes in the distribution of ventilation to perfusion ratio in the lungs. 1–4 Classically, respiratory dead space is divided into two parts: anatomical dead space ( V d F) and alveolar dead space. The measurement of respiratory dead space, which provides important insight into the efficiency of gas exchange, has found wide application in respiratory physiology, clinical anaesthesia, and critical care medicine.

Calculate anatomical dead space