Pulmonary and cardiovascular effects of apneic oxygenation in man

Abstract

Apneic oxygenation was studied in 13 patients undergoing Jako laryngoscopy with a pharyngeal catheter for oxygen administration and 18 patients having minor surgical procedures with a cuffed endotracheal tube in place for oxygen administration. Arterial pO2, pCO2 and pH, functional residual capacity (FRC), alveolar pN2 oxygen uptake, arterial blood pressure, and the electrocardiogram were observed. There was essentially no difference in oxygenation achieved with the two methods of oxygen administration. The majority of patients (22) tolerated apneic axygenation for 15 min or longer. Nine patients could not tolerate apneic oxygenation for more than 5 min. These patients had relatively smaller masses, for a predicted FRC/weight ratio of predicted and actual FRC's and larger body 36.7 ± 9 ml/kg, whereas the other patients had a predicted FRC/weight ratio of 53.3 ± 7.7 ml/kg. Because of the smaller FRC and larger body mass, accumulation of alveolar nitrogen resulted in higher pN2(a)'s and lower pO2(a)'s in patients with low FRC/weight ratios.