pulmonary fibrosis is shunt vs dead space

2 The dead space on V T (V D/V T) ratio informs caregivers as to the effect of therapeutic procedures such as prone positioning, 3 surfactant administration, 4 or lung recruitment maneuvers 5, 6 and provides information useful in prognostication, depending on the severity of lung disease in adults and children. 1 Currently, physiologic dead space measurement is used by clinicians in the management of mechanical ventilation because CO 2 removal is inversely proportional to V D/V T, and V D fluctuates considerably, depending upon the severity of lung disease. 1 Later, Enghoff proposed a simplification of Bohr's formulae to calculate the physiologic dead space ratio at the bedside using arterial P CO 2 (P aCO 2) instead of P ACO 2. Employing the law of mass conservation, Bohr proposed a formula using alveolar P CO 2 (P ACO 2) to estimate physiologic dead space, expressed as a ratio of dead space volume (V D) to tidal volume (V T). Lung physiologic dead space (V D) is defined as the wasted tidal volume during respiration (ie, the volume remaining in the conducting airways and in poorly perfused and non-perfused alveoli that are not participating in gas exchange).

Pulmonary fibrosis is shunt vs dead space