Ventilatory-perfusion relationships and respiratory drive in chronic obstructive pulmanory disease : With special reference to hypoxaemia, sleep quality and treatment with inhaled corticisteroid

By measuring retention in blood and excretion in exhaled air of six infused inert gases using multiple inert gas technique (MIGET), it is possible to obtain detailed assessment of the ventilation-perfusion (VA/Q) relationships in patients with chronic obstructive pulmonary disease. Stable, non-bronchitic COPD patients show a substantial perfusion of hyper-ventilated lung regions. For individuals with exclusively nocturnal hypoxaemia, when the nocturnal arterial oxygen saturation (Sa02) is below 90%, an increase in dispersion of ventilation (log SW) is present together with significantly prolonged superficial sleep compared with normal. Substantial perfusion of relatively poorly ventilated lung areas (0.1A/Q