抬高体位对机械通气患者腹腔压力和胃食管反流的综合影响

Combined effects of elevated body position on gastroesophageal reflux and intra-abdominal pressure in mechanical ventilated patients

目的探讨抬高体位对机械通气重症患者腹腔压力（IAP）和胃食管反流的综合影响，以期为机械通气胃肠营养患者寻找合理的床头角度。方法选择2010年3月至12月收入本院重症监护病房（ICU）并采用机械通气辅助呼吸和胃肠营养支持的41例非胃食管反流病（GERD）患者，采用不同体位（0°、20°、30°、45°）持续6hpH一阻抗和IAP联合监测。结果①液体反流以弱酸性和无酸性反流为主，仅偶见酸性反流。体位在0°～30°变化时，随体位的抬高累积液体反流次数显著减少，高位食管反流的比例呈下降趋势（0°：20°：30°的反流次数：酸性3．0：2．0：1．0，弱酸性13．0：9．0：6．0，无酸性4．0：3．0：2．0；0°：20°：30°的高位食管反流比例：酸性16．00%：9．00％：7．84％，弱酸性68．40％：47．40％：46．69％，无酸忡15．61％：9．82％：8.89％，P〈0．05或P〈0．01）；但由30。增至45。时，不但液体反流次数无明显改变，高位反流比例反而显著增加（30°：45°的反流次数：酸性1．0：1．0，弱酸性6．0：5．0，无酸性2．0：2．0，均P〉0．05；30°：45°的高位反流比例：酸性7．84％：12．00％，弱酸性46．69％：52．29％，无酸性8．89％：17．58％，均P〈0．05）。⑧41例患者中有4例（9．76%）在0°体位时即存在腹腔高压（IAH），其中1例为N级IAH（〉25mmHg，1mmHg=0．133kPa）；随体位的抬高患者IAP呈增高趋势[0°、20°、30°、45°的IAP（mmHg）分别为10．32±3．48、11．33±3．71、13．55±3．58、18．25±3．82，P〈0．01]；体位每增加一个等级，IAP的增加率均显著提高[0°～20°（9．74±3．05）％，20°～30°（19．60土5．67）％，30°～45°（34．73±7．67）％，两两比较均JP〈0．01]；由30°增至45°时，患者出现各级别IAH的例数也显著增加（Ⅰ级分别为5：8，Ⅱ级分别为2：5，Ⅲ级分别为3：5，Ⅳ级分别为2；3，P〈0．05或P〈0．01）。结论抬高体位虽可一定程度地减轻机械通气重症患者的胃食管反流，但却能导致IAP增加；尤其是当体位升高至45°时，抬高体位不但不能有效减少反流次数，同时还可提升反流的高度并显著增加患者的IAP。因此，30°可能是机械通气胃肠营养患者较理想的体位。

Objective To investigate the combined effects of elevated body position on gastroe- sophageal reflux and intra abdominal pressure （IAP） in patients undergoing mechanical ventilation （MV） who were receiving enteral nutrition, and to find out their proper height of head of bed. Methods The continuous pH-impedance and bladder pressure （reflecting IAP） at different body positions （0°, 20°, 30°, 45°） in 6 hours were monitored in 41 MV and enteral nutrition supported patients. The patients who did not have previous gastroesophageal reflux disease （GE1RD） were admitted to intensive care unit （ICU） of Peking University Third Hospital from March 2010 to December 2010 were included in the study. Results （1）The most common fluid reflux were weak acid and non-acid reflux. Acid reflux was rare. When elevating the body position from 0° to 30°, the accumulated numbers of these 3 kinds of reflux were declined significantly, and the percentage of high esophageal reflux decreased significantly （numbers of reflux.. 0° ： 20° ： 30°.. acid 3.0 ： 2.0 ： 1.0, weak acid 13.0 ： 9.0 ： 6.0, non-acid 4.0 ：3.0 ： 2.0; percentage of high esophageal reflux.. 0° .. 20° ： 30°： acid 16.00%：9.00%：7.84% weak acid 68.40% ： 47.40%o ： 46.69%;non-acid 15.61% ： 9.82%. 8.89%, P〈0. 05 or P（0.01）. But when elevating the body position from 30° to 45°, no more significant changes in the numbers of reflux were found, instead, the percentage of high esophageal reflux increased （numbers of reflux 30% ： 45%： acid 1.0 ： 1- 0, weak acid 6.0 ： 5.0, non-acid 2.0 ： 2.0, all P〉 0.05; percentage of high esophageal reflux 30%： 45% acid 7.84% ： 12.00%, weak acid 46.69% ： 52.29%, non-acid 8.89% ： 17.58G, all P〈0.05）. （2） Four of the 41 patients （9.76%, 4/41） were found to have intra-abdominal hypertension （IAH） at 0f body position, with one patient at Ⅳ degree （IAH〉25 mm Hg, 1 mm Hg= 0. 133 kPa）. With the patients, body position elevated, the IAP appeared to be further increased [the IAP （ram Hg） at 0° 20°, 30°, 45° position were 10.32±3.48, 11.33±3.71, 13.55±3.58 and 18.25° 3.82, respectively P（0.01]~ with each level of elevation of the body position, the increasing rate was enhanced markedly [the increasing rate of IAP from 0° to 20°, 20° to 30° and 30° to 45° were （9.74~ 3.05） V00, （19.60~5.67）% and （34.73~ 7.67）%, respectively, the difference between any two groups was significam, all P〈0.01]. When elevating the body position from 30° to 45°, the numbers of patients with different levels of IAH were increased significantly too （30°： 45°： level 1： 5 ： 8; level Ⅱ ： 2 ： 5; level Ⅲ ： 3 ： 5; level Ⅳ ： 2 ： 3, P〈0. 05 or P〈0. 01）. Conclusion Although elevation of the body position of MV patients can reduce gastroesophageal reflux, it also increase the IAP. When the body position is elevated to 45°, the number of reflux is not reduced effectively, while the rate of high esophageal reflux and the patientsr IAP are increased significantly, indicating that 30° might be the proper body position for the MV patients receiving enteral nutrition.