The effect of positive airway pressure during pre-oxygenation and induction of anaesthesia upon duration of non-hypoxic apnoea

Anaesthesia. 2004 Mar;59(3):243-7. doi: 10.1111/j.1365-2044.2004.03615.x.


Positive end-expiratory pressure (PEEP) applied during induction of anaesthesia may prevent atelectasis formation in the lungs. This may increase the duration of non-hypoxic apnoea by increasing the functional residual capacity. We studied the benefit of PEEP applied during the induction of anaesthesia on the duration of apnoea until the SpO2 reached 90%. Forty ASA I-II patients were randomly allocated to one of two groups. In the PEEP group (n = 20) patients were pre-oxygenated using 100% O2 administered using a CPAP device (6 cmH2O) for 5 min. Following induction of anaesthesia, patients were mechanically ventilated (PEEP 6 cm H2O) for a further 5 min. In the ZEEP group (n = 20), no CPAP or PEEP was used. The duration of apnoea until SpO2 reached 90% was measured. Non-hypoxic apnoea duration was longer in the PEEP group compared to ZEEP group (599 +/- 135 s vs. 470 +/- 150 s, p = 0.007). We conclude that the application of positive airway pressure during induction of anaesthesia in adults prolongs the non-hypoxic apnoea duration by > 2 min.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Anesthesia, General / adverse effects*
  • Carbon Dioxide / blood
  • Female
  • Humans
  • Intraoperative Complications / prevention & control*
  • Male
  • Middle Aged
  • Oxygen / blood*
  • Oxygen Inhalation Therapy*
  • Partial Pressure
  • Positive-Pressure Respiration*
  • Pulmonary Atelectasis / etiology
  • Pulmonary Atelectasis / prevention & control*
  • Time Factors


  • Carbon Dioxide
  • Oxygen