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

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.