NIPPV for Preoxygenation in Morbidly Obese Patients
BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) with pressure support-ventilation and positive end-expiratory pressure are effective in providing oxygenation during intubation in hypoxemic patients. We hypothesized administration of oxygen (O2) using NPPV would more rapidly increase the end-tidal O2 concentration (ETo2) than preoxygenation using spontaneous ventilation (SV) in morbidly obese patients.
METHODS: Twenty-eight morbidly obese patients were enrolled in this prospective randomized study. Administration of O2 for 5 min was performed either with SV group or with NPPV (pressure support = 8 cm H2O, positive end-expiratory pressure = 6 cm H2O) (NPPV group). ETo2 was measured using the anesthesia breathing circuit, and is expressed as a fraction of atmospheric concentration. The primary end-point was the number of patients with an ETo2 >95% at the end of O2 administration. Secondary end-points included the time to reach the maximal ETo2 and the ETo2 at the conclusion of O2 administration.
RESULTS: A larger proportion of patients achieved a 95% ETo2 at 5 min with NPPV than SV (13/14 vs 7/14, P = 0.01). The time to reach the maximal ETo2 was significantly less in the NPPV than in the SV group (185 ± 46 vs 222 ± 42 s, P = 0.02). The mean ETo2 at the conclusion of O2 administration was larger in the NPPV group than the SV group (96.9 ± 1.3 vs 94.1 ± 2.0%, P < 0.001). A modest, although significant, increase in gastric distension was observed in the NPPV group. No adverse effects were observed in either group.
CONCLUSION: Administration of O2 via a facemask with NPPV in the operating room is safe, feasible, and efficient in morbidly obese patients. In this population NPPV provides a more rapid O2 administration, achieving a higher ETo2.
IMPLICATIONS: Noninvasive positive pressure ventilation provides a more rapid preoxygenation, achieving a higher end-tidal oxygen concentration, than spontaneous ventilation in morbidly obese patients.
BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) with pressure support-ventilation and positive end-expiratory pressure are effective in providing oxygenation during intubation in hypoxemic patients. We hypothesized administration of oxygen (O2) using NPPV would more rapidly increase the end-tidal O2 concentration (ETo2) than preoxygenation using spontaneous ventilation (SV) in morbidly obese patients.
METHODS: Twenty-eight morbidly obese patients were enrolled in this prospective randomized study. Administration of O2 for 5 min was performed either with SV group or with NPPV (pressure support = 8 cm H2O, positive end-expiratory pressure = 6 cm H2O) (NPPV group). ETo2 was measured using the anesthesia breathing circuit, and is expressed as a fraction of atmospheric concentration. The primary end-point was the number of patients with an ETo2 >95% at the end of O2 administration. Secondary end-points included the time to reach the maximal ETo2 and the ETo2 at the conclusion of O2 administration.
RESULTS: A larger proportion of patients achieved a 95% ETo2 at 5 min with NPPV than SV (13/14 vs 7/14, P = 0.01). The time to reach the maximal ETo2 was significantly less in the NPPV than in the SV group (185 ± 46 vs 222 ± 42 s, P = 0.02). The mean ETo2 at the conclusion of O2 administration was larger in the NPPV group than the SV group (96.9 ± 1.3 vs 94.1 ± 2.0%, P < 0.001). A modest, although significant, increase in gastric distension was observed in the NPPV group. No adverse effects were observed in either group.
CONCLUSION: Administration of O2 via a facemask with NPPV in the operating room is safe, feasible, and efficient in morbidly obese patients. In this population NPPV provides a more rapid O2 administration, achieving a higher ETo2.
IMPLICATIONS: Noninvasive positive pressure ventilation provides a more rapid preoxygenation, achieving a higher end-tidal oxygen concentration, than spontaneous ventilation in morbidly obese patients.
