Clinical Application of Continuous Flow Apneic Ventilation

Continuous flow apneic ventilation (CFAV) was studied in five adult female patients. After induction of anesthesia with thiopental sodium (5 mg/kg) and fentanyl (5 μg/kg), and paralysis with pancuronium bromide (0.12 mg/kg), the patients were ventilated with oxygen at an FIO2 of 1.0 by face mask. Two polyethylene catheters (outside diameter [OD] 2.5 mm) were each inserted into the right and left mainstem bronchi. Each catheter had a curved tip measuring 2 cm in length. The angulation of the catheter tip from the axis was 20° for the right side and 30° for the left side. The endobronchial position was checked by fiberoptic bronchoscopy. Subsequently, tracheal intubation was performed using a 7.5 mm OD tracheal tube. CFAV was started when both catheters were connected to the gas delivery system. Humidified oxygen was delivered at total flows between 0.6 and 0.7 1/min. Arterial blood gases were analyzed every 5 min for 30 min. Monitoring included electrocardiogram, indirect blood pressure, heart rate, temperature, and peripheral nerve stimulation. Adequate oxygenation was maintained in all patients, 39.76 ± 4.32 kPa (299 ± 37 mmHg) at 30 min. There was a significant rise in Paco2 (P<0.05) at 30 min compared to the control, 4.92 ± 0.25 kPa compared to 7.30 ± 0.53 kPa (37.0 ± 1.9 mmHg compared to 54.9 ± 4.0 mmHg). There was a mean rise in Paco2 of 0.03 kPa/min (0.6 mmHg/min) compared to 0.5 kPa/min (3.8 mmHg/min) with apneic diffusion ventilation. In one patient there was no increase in Paco2 during the 30 min of CFAV. The results demonstrate that CFAV can maintain blood gases in a clinically useful range for as long as 30 min.