呼气末正压可改善肥胖患者在麻醉和麻痹期间的呼吸功能，但对正常受试者无效。

Positive end-expiratory pressure improves respiratory function in obese but not in normal subjects during anesthesia and paralysis.

作者信息

Pelosi P, Ravagnan I, Giurati G, Panigada M, Bottino N, Tredici S, Eccher G, Gattinoni L

机构信息

Istituto di Anestesia e Rianimazione, Università di Milano, Ospedale Magiore, Istituto di Ricovero e Cura a Carattere Scientifico, Milan, Italy.

出版信息

Anesthesiology. 1999 Nov;91(5):1221-31. doi: 10.1097/00000542-199911000-00011.

DOI:10.1097/00000542-199911000-00011

PMID:10551570

Abstract

BACKGROUND

Morbidly obese patients, during anesthesia and paralysis, experience more severe impairment of respiratory mechanics and gas exchange than normal subjects. The authors hypothesized that positive end-expiratory pressure (PEEP) induces different responses in normal subjects (n = 9; body mass index < 25 kg/m2) versus obese patients (n = 9; body mass index > 40 kg/m2).

METHODS

The authors measured lung volumes (helium technique), the elastances of the respiratory system, lung, and chest wall, the pressure-volume curves (occlusion technique and esophageal balloon), and the intraabdominal pressure (intrabladder catheter) at PEEP 0 and 10 cm H2O in paralyzed, anesthetized postoperative patients in the intensive care unit or operating room after abdominal surgery.

RESULTS

At PEEP 0 cm H2O, obese patients had lower lung volume (0.59 +/- 0.17 vs. 2.15 +/- 0.58 l [mean +/- SD], P < 0.01); higher elastances of the respiratory system (26.8 +/- 4.2 vs. 16.4 +/- 3.6 cm H2O/l, P < 0.01), lung (17.4 +/- 4.5 vs. 10.3 +/- 3.2 cm H2O/l, P < 0.01), and chest wall (9.4 +/- 3.0 vs. 6.1 +/- 1.4 cm H2O/l, P < 0.01); and higher intraabdominal pressure (18.8 +/-7.8 vs. 9.0 +/- 2.4 cm H2O, P < 0.01) than normal subjects. The arterial oxygen tension was significantly lower (110 +/- 30 vs. 218 +/- 47 mmHg, P < 0.01; inspired oxygen fraction = 50%), and the arterial carbon dioxide tension significantly higher (37.8 +/- 6.8 vs. 28.4 +/- 3.1, P < 0.01) in obese patients compared with normal subjects. Increasing PEEP to 10 cm H2O significantly reduced elastances of the respiratory system, lung, and chest wall in obese patients but not in normal subjects. The pressure-volume curves were shifted upward and to the left in obese patients but were unchanged in normal subjects. The oxygenation increased with PEEP in obese patients (from 110 +/-30 to 130 +/- 28 mmHg, P < 0.01) but was unchanged in normal subjects. The oxygenation changes were significantly correlated with alveolar recruitment (r = 0.81, P < 0.01).

CONCLUSIONS

During anesthesia and paralysis, PEEP improves respiratory function in morbidly obese patients but not in normal subjects.

摘要

背景

病态肥胖患者在麻醉和麻痹状态下，呼吸力学和气体交换功能的受损程度比正常受试者更严重。作者推测，呼气末正压（PEEP）在正常受试者（n = 9；体重指数<25 kg/m²）与肥胖患者（n = 9；体重指数>40 kg/m²）中会引发不同的反应。

方法

作者在重症监护病房或腹部手术后手术室中，对处于麻痹、麻醉状态的术后患者，于呼气末正压为0和10 cm H₂O时，测量肺容量（氦气法）、呼吸系统、肺和胸壁的弹性、压力-容量曲线（阻断法和食管气囊法）以及腹腔内压力（膀胱内导管法）。

结果

在呼气末正压为0 cm H₂O时，肥胖患者的肺容量较低（0.59±0.17 vs. 2.15±0.58 l[平均值±标准差]，P<0.01）；呼吸系统（26.8±4.2 vs. 16.4±3.6 cm H₂O/l，P<0.01）、肺（17.4±4.5 vs. 10.3±3.2 cm H₂O/l，P<0.01）和胸壁（9.4±3.0 vs. 6.1±1.4 cm H₂O/l，P<0.01）的弹性较高；腹腔内压力也高于正常受试者（18.8±7.8 vs. 9.0±2.4 cm H₂O，P<0.01）。肥胖患者的动脉血氧分压显著较低（110±30 vs. 218±47 mmHg，P<0.01；吸入氧分数=50%），动脉血二氧化碳分压显著较高（37.8±6.8 vs. 28.4±3.1，P<0.01）。将呼气末正压增至10 cm H₂O可显著降低肥胖患者呼吸系统、肺和胸壁的弹性，但对正常受试者无此影响。肥胖患者的压力-容量曲线向上和向左移动，而正常受试者则无变化。肥胖患者的氧合随着呼气末正压增加（从110±30增至130±28 mmHg，P<0.01），而正常受试者则无变化。氧合变化与肺泡复张显著相关（r = 0.81，P<0.01）。