Noninvasive Ventilation and Alveolar Recruitment Maneuver Improve Respiratory Function during and after Intubation of Morbidly Obese Patients: a randomized controlled study.

Morbid obesity predisposes patients to lung collapse and hypoxemia during induction of anesthesia. The aim of this prospective study was to determine whether noninvasive positive pressure ventilation (NPPV) improves arterial oxygenation and end-expiratory lung volume (EELV) compared with conventional preoxygenation, and whether NPPV followed by early recruitment maneuver (RM) after endotracheal intubation (ETI) further improves oxygenation and respiratory function compared with NPPV alone. METHODS: Sixty-six consecutive patients (body mass index, 46 \ub1 6 kg/m\ub2) were randomized to receive 5 min of either conventional preoxygenation with spontaneous breathing of 100% O\u2082 (CON), NPPV (pressure support and positive end-expiratory pressure), or NPPV followed by RM (NPPV+RM). Gas exchange was measured in awake patients, at the end of preoxygenation, immediately after ETI, and 5 min after the onset of mechanical ventilation. EELV was measured immediately after ETI and 5 min after mechanical ventilation. The primary endpoint was arterial oxygenation 5 min after the onset of mechanical ventilation. Results are presented as mean \ub1 SD. RESULTS: At the end of preoxygenation, Pao\u2082 was higher in the NPPV and NPPV+RM groups (382 \ub1 87 mmHg and 375 \ub1 82 mmHg, respectively; both P < 0.001) compared with the CON group (306 \ub1 51 mmHg) and remained higher after ETI (225 \ub1 104 mmHg and 221 \ub1 110 mmHg, in the NPPV and NPPV+RM groups, respectively; both P < 0.01 compared with the CON group [150 \ub1 50 mmHg]). After the onset of mechanical ventilation, Pao\u2082 was 93 \ub1 25 mmHg in the CON group, 128 \ub1 54 mmHg in the NPPV group (P = 0.035 vs. CON group), and 234 \ub1 73 mmHg in the NPPV+RM group (P < 0.0001 vs. NPPV group). After ETI, EELV was higher in the NPPV group compared with the CON group (P < 0.001). Compared with NPPV alone, RM further improved gas exchange and EELV (all P < 0.05). A significant correlation was found between Pao2 obtained 5 min after mechanical ventilation and EELV (R = 0.41, P < 0.001). CONCLUSION: NPPV improves oxygenation and EELV in morbidly obese patients compared with conventional preoxygenation. NPPV combined with early RM is more effective than NPPV alone at improving respiratory function after ETI