Arterial oxygenation differences with carbon dioxide-induced versus voluntary increases in minute ventilation in chronic airway obstruction.

Two groups of patients with similar degrees of chronic airway obstruction exhibited different degrees of increased arterial oxygenation with CO2-induced hyperpnea versus voluntary increases in ventilation matched for ventilatory pattern. Patients who failed to increase arterial PO2 as much with voluntary hyperventilation as with CO2 challenge also had a lower dynamic compliance with the voluntary maneuver, whereas those with similar increases in arterial PO2 had similar dynamic compliances during the 2 periods of increased minute ventilation. The differences between the 2 groups are believed to be related to different effects of hypocapnia on collateral ventilation.