Department of Anesthesiology and Critical Care Medicine, Estaing Hospital, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France.
Anesthesiology. 2011 Jun;114(6):1354-63. doi: 10.1097/ALN.0b013e31821811ba.
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.
Sixty-six consecutive patients (body mass index, 46 ± 6 kg/m²) were randomized to receive 5 min of either conventional preoxygenation with spontaneous breathing of 100% O₂ (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 ± SD.
At the end of preoxygenation, Pao₂ was higher in the NPPV and NPPV+RM groups (382 ± 87 mmHg and 375 ± 82 mmHg, respectively; both P < 0.001) compared with the CON group (306 ± 51 mmHg) and remained higher after ETI (225 ± 104 mmHg and 221 ± 110 mmHg, in the NPPV and NPPV+RM groups, respectively; both P < 0.01 compared with the CON group [150 ± 50 mmHg]). After the onset of mechanical ventilation, Pao₂ was 93 ± 25 mmHg in the CON group, 128 ± 54 mmHg in the NPPV group (P = 0.035 vs. CON group), and 234 ± 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).
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.
病态肥胖使患者在麻醉诱导期间容易发生肺塌陷和低氧血症。本前瞻性研究旨在确定与常规预充氧相比，无创正压通气（NPPV）是否能改善动脉氧合和呼气末肺容积（EELV），以及与单独使用 NPPV 相比，NPPV 后紧接着进行早期复张手法（RM）是否能进一步改善氧合和呼吸功能。
66 例连续患者（体重指数 46 ± 6 kg/m²）随机接受 5 分钟的常规预充氧（自主呼吸 100% O₂，CON）、NPPV（压力支持和呼气末正压）或 NPPV 后紧接着 RM（NPPV+RM）。在清醒患者中测量气体交换，在预充氧结束时、气管插管（ETI）后即刻和机械通气开始后 5 分钟测量。在 ETI 后即刻和机械通气后 5 分钟测量 EELV。主要终点是机械通气开始后 5 分钟的动脉氧合。结果以平均值 ± 标准差表示。
在预充氧结束时，NPPV 和 NPPV+RM 组的 Pao₂（分别为 382 ± 87 mmHg 和 375 ± 82 mmHg；均 P < 0.001）高于 CON 组（306 ± 51 mmHg），并且在 ETI 后仍然较高（分别为 225 ± 104 mmHg 和 221 ± 110 mmHg；NPPV 和 NPPV+RM 组均 P < 0.01 与 CON 组 [150 ± 50 mmHg]）。在机械通气开始后，CON 组的 Pao₂为 93 ± 25 mmHg，NPPV 组为 128 ± 54 mmHg（P = 0.035 与 CON 组），NPPV+RM 组为 234 ± 73 mmHg（P < 0.0001 与 NPPV 组）。在 ETI 后，NPPV 组的 EELV 高于 CON 组（P < 0.001）。与单独使用 NPPV 相比，RM 进一步改善了气体交换和 EELV（均 P < 0.05）。机械通气后 5 分钟获得的 Pao₂与 EELV 之间存在显著相关性（R = 0.41，P < 0.001）。
与常规预充氧相比，NPPV 可改善病态肥胖患者的氧合和 EELV。与单独使用 NPPV 相比，NPPV 后紧接着进行早期 RM 能更有效地改善 ETI 后的呼吸功能。
