High frequency jet ventilation v. manual jet ventilation during bronchoscopy in patients with tracheo-bronchial stenosis.

Six patients with airway stenosis were submitted to bronchoscopy under general anaesthesia. Each was ventilated with a gas mixture of 50% oxygen and nitrogen using successively manual jet insufflation (JV) using the Sanders technique at 20 b.p.m., and high frequency jet ventilation (HFJV) at rates of 150, 300 and 500 b.p.m. The effects on alveolar ventilation were assessed by blood-gas analysis and the transcutaneous monitoring of carbon dioxide tension. It is concluded that HFJV achieves satisfactory operating conditions, and provides adequate gas exchanges up to a rate of 300 b.p.m. At the faster rate some degree of hypoxaemia and hypercarbia were noted. The correlation between PaCO2 and transcutaneous carbon dioxide tension was satisfactory.