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Efficacy of preoxygenation with non-invasive low positive pressure ventilation in obese patients: crossover
M Georgescu1, I Tanoubi, L-P Fortier
1Département d'anesthesiologie, hôpital Maisonneuve-Rosemont, centre affilié à l'université de Montréal, 5415, boulevard de l'Assomption, Montréal (Québec) Canada, H1T 2M4.
Objective:
The impact of non-invasive positive pressure ventilation (NIPPV), which is a combination of inspiratory positive airway pressure (IPAP) and positive end expiratory pressure (PEEP), on the effectiveness of preoxygenation in obese patients was evaluated.
Design:
Randomized, controlled, double blinded, crossover study comparing NIPPV vs. tidal volume breathing (TVB) with regard to the expiratory O(2) fraction (FeO(2)).
Patients And Methods:
Thirty participants with body mass index (BMI) greater or equal to 30 kg/m(2) scheduled for elective surgery were included. Patients with facial hair, and airway anomalies were excluded. Each patient underwent 3 minutes 100% O(2) preoxygenation with the two following methods in a random order: 1: TVB; 2: NIPPV (4 cmH(2)O IPAP+4 cmH(2)O PEEP). Primary outcome was FeO(2) after 3 minutes. Secondary outcomes were the number of patients reaching FeO(2) greater or equal to 90%, tidal volume, respiratory rate, and patient comfort on a 4-point scale.
Results:
No differences between methods were found regarding the FeO(2) change with time or after 3 minutes (89 ± 6% with TBV vs. 91 ± 4% with NIPPV). FeO(2) greater or equal to 90% was reached more frequently with NIPPV (80%) than with TVB (60%) (P=0.008). Tidal volume (m ± SD) was larger throughout preoxygenation with TBV (837 ± 440 mL) than with NIPPV (744 ± 368 mL), (P=0.0005). Respiratory rate did not differ between regimens. Patient comfort was good and similar.
Conclusion:
This study suggests that providing a positive pressure of 4 cmH(2)O throughout inspiration and expiration during preoxygenation in obese patients provided benefits with regard to the FeO(2).
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