Apnetic anesthesia for microlaryngeal surgery

An apneic anesthesia state can be induced and maintained with intravenous thiopental, succinylcholine, and 100 percent oxygen at 6L/min. by catheter. This technique allows an unobstructed view of the endolarynx, avoids trauma of the larynx by an endotracheal tube prior to diagnostic procedures, and precludes seeding the larynx and trachea with malignant cells. The rise in PnCO2 is 3 mm Hg/min. Arrhythmias that occur with laryngeal manipulation bear no relation to the level of arterial carbon dioxide. Patients can tolerate this technique for a minimum of 10 minutes, but eight of 31 patients could not tolerate the condition beyond that time. The subjects with apneic intolerance were found to have relatively low functional residual capacities and were relatively obese. An FRC/WT. above 17 was considered an indicator of high apneic tolerance, and an FRC/WT. below 15 an indicator of a patient who should be monitored closely. WT/IPPB should always be administered postoperatively.