Continuous flow ventilation without respiratory movement in cat, dog and human.

The insufflation of oxygen at 1 litre kg-1 min-1 via two endobronchial catheters (called continuous flow ventilation (CFV)) maintained a normal PaCO2 and a constant PaO2 in anaesthetized paralysed dogs and in five out of seven cats. In two cats with a high carbon dioxide production, CFV failed to maintain carbon dioxide homeostasis since gas flows greater than 1 litre kg-1 min-1 caused thoracic distension and a decrease in arterial pressure. In five patients, endobronchial insufflation of oxygen 0.5 litre kg-1 min-1 caused approximately a 30% decrease in the increase in PaCO2 compared with apnoeic oxygenation (P less than 0.05) during a period of 6 min. CFV at 1 litre kg-1 min-1 can be used for physiological measurement without respiratory movement while maintaining blood-gas homeostasis in dogs and in cats with a normal carbon dioxide production. Ethical constraints have so far prevented the investigation of the effects of comparable gas flows in man.