One-lung and two-lung high frequency ventilation (HFV) through a 2-mm internal diameter catheter was evaluated in 22 patients during endoscopic laser excision of stenotic lesions of larynx, trachea, and bronchi. High frequency ventilation at 80 to 250 breaths per minute using air during two-lung HFV and using air-oxygen at an inspired oxygen concentration of 25 % during one-lung HFV maintained adequate alveolar ventilation and oxygenation in all patients. The use of HFV through a catheter allowed continuous control of ventilation and provided maximal surgical exposure for endoscopic laser surgery. The continuous outflow of HFV gases through the endoscope also prevented lung contamination with blood and debris. The potential of HFV polyvinylchloride catheter ignition by laser was also evaluated in the laboratory during continuous flow of air-oxygen and oxygen-nitrous oxide. The laser ignited polyvinylchloride tubes in all the mixtures of oxygen and nitrous oxide within 3 to 7 seconds. Oxygen at 30% mixed with nitrogen 70% was safe and all such tubes were not ignited by the laser. The ability of HFV to provide adequate oxygenation during endoscopic laser surgery using air-oxygen at an FiO2 below 30% also avoids the hazard of catheter and airway fire.
