Low-positive pressure ventilation system improves non-hypoxemic apnoea tolerance

Inhalt:
Objective: To determine pre-oxygenation with PSV increases the duration of non-hypoxemic apnoea in non-obese patients. Method： 50 patients scheduled pan-endoscopy were enrolled to receive either 100% oxygen at neutral pressure (control group) or 100% oxygen with positive-pressure ventilation (a positive inspiratory and end-expiratory pressure of 4 cmH2O, PSV group) during spontaneous ventilation with a face mask. The goal of pre-oxygenation was to obtain an end-tidal oxygen concentration of more than 90% prior to induction of anaesthesia. Results: The mean (inter-quartile range) duration of non-hypoxemic apnoea was longer in the PSV group than control group (P < 0.001). Oxygenation time was shorter in the PSV group than control group (P=0.037). The inter-group difference in the duration of pan-endoscopy was not significant. Tolerance was good or very good in all patients. Conclusion: oxygenation with PSV is associated with a longer duration of non-hypoxemic apnoea and a lower frequency of manual re-ventilation.