Nguyen N T, Anderson J T, Budd M, Fleming N W, Ho H S, Jahr J, Stevens C M, Wolfe B M
Department of Surgery, University of California, Irvine Medical Center, 101 The City Drive, Building 55, Room 106, Orange, CA 92868, USA.
Surg Endosc. 2004 Jan;18(1):64-71. doi: 10.1007/s00464-002-8786-x. Epub 2003 Nov 21.
Hypercarbia and elevated intraabdominal pressure resulting from carbon dioxide (CO2) pneumoperitoneum can adversely affect respiratory mechanics. This study examined the changes in mechanical ventilation, CO2 homeostasis, and pulmonary gas exchange in morbidly obese patients undergoing a laparoscopic or open gastric bypass (GBP) procedure.
In this study, 58 patients with a body mass index (BMI) of 40 to 60 kg/m2 were randomly allocated to laparoscopic ( n = 31) or open ( n = 27) GBP. Minute ventilation was adjusted to maintain a low normal arterial partial pressure of CO2 (PaCO2), low normal end-tidal partial pressure of CO2 (ETCO2), and low airway pressure. Respiratory compliance, ETCO2, peak inspiratory pressure (PIP), total exhaled CO2 per minute (VCO2), and pulse oximetry (SO2) were measured at 30-min intervals. The acid-base balance was determined by arterial blood gas analysis at 1-h intervals. The pulmonary gas exchange was evaluated by calculation of the alveolar dead space-to-tidal volume ratio (V(Dalv)/V(T)) and alveolar-arterial oxygen gradient (PAO2-PaO2).
The two groups were similar in age, gender, and BMI. As compared with open GBP, laparoscopic GBP resulted in higher ETCO2, PIP, and VCO2, and a lower respiratory compliance. Arterial blood gas analysis demonstrated higher PaCO2 and lower pH during laparoscopic GBP than during open GBP ( p < 0.05). The V(Dalv)/V(T) ratio and PAO2-PaO2 gradient did not change significantly during laparoscopic GBP. Intraoperative oxygen desaturation (SO2 < 90%) did not develop in any of the patients in either group.
Laparoscopic GBP alters intraoperative pulmonary mechanics and acid-base balance but does not significantly affect pulmonary oxygen exchange. Changes in pulmonary mechanics are well tolerated in morbidly obese patients when proper ventilator adjustments are maintained.
二氧化碳气腹导致的高碳酸血症和腹内压升高会对呼吸力学产生不利影响。本研究探讨了接受腹腔镜或开放胃旁路手术（GBP）的病态肥胖患者机械通气、二氧化碳稳态及肺气体交换的变化。
本研究中，58例体重指数（BMI）为40至60kg/m²的患者被随机分为腹腔镜组（n = 31）和开放组（n = 27）接受GBP手术。调整分钟通气量以维持动脉血二氧化碳分压（PaCO₂）、呼气末二氧化碳分压（ETCO₂）处于低正常水平，气道压力处于低水平。每隔30分钟测量呼吸顺应性、ETCO₂、吸气峰压（PIP）、每分钟呼出二氧化碳总量（VCO₂）及脉搏血氧饱和度（SO₂）。每隔1小时通过动脉血气分析测定酸碱平衡。通过计算肺泡死腔与潮气量比值（V(Dalv)/V(T)）及肺泡-动脉血氧分压差（PAO₂ - PaO₂）评估肺气体交换。
两组患者在年龄、性别及BMI方面相似。与开放GBP相比，腹腔镜GBP导致更高的ETCO₂、PIP及VCO₂，以及更低的呼吸顺应性。动脉血气分析显示，腹腔镜GBP期间的PaCO₂高于开放GBP，pH低于开放GBP（p < 0.05）。腹腔镜GBP期间V(Dalv)/V(T)比值及PAO₂ - PaO₂梯度无显著变化。两组患者术中均未出现氧饱和度下降（SO₂ < 90%）。
腹腔镜GBP改变术中肺力学及酸碱平衡，但对肺氧交换无显著影响。当维持适当的呼吸机调整时，病态肥胖患者对肺力学的变化耐受性良好。
