校正体重设置肥胖患者全身麻醉机械通气潮气量的可行性

Feasibility of using corrected body weight to set tide volume for mechanical ventilation during general anesthesia in obese patients

目的 评价校正体重设置肥胖患者全身麻醉机械通气潮气量的可行性.方法 肥胖患者60例,拟全麻下择期手术,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将其分成3组（n=20）：实际体重潮气量组（A组）、理想体重潮气量组（I组）和校正体重潮气量组（C组）.麻醉诱导后气管插管,根据相应体重水平,按8 ml/kg设置机械通气初始潮气量,呼吸频率15次/min.于机械通气开始后10min记录气道峰压（Ppeak）、气道平台压（Pp1at）和气道阻力（Raw）,机械通气30 min时采集动脉血行血气分析,并记录PaO2、PaCO2及患者需调整潮气量的发生情况.结果 与A组比较,I组和C组PaCO2升高,Ppeak、Pplat、Raw降低（P＜0.01）；与I组比较,C组PaCO2降低,Ppeak、Pplat、Raw升高（P＜0.01或0.05）；患者需调整潮气量的发生率,C组为0,而A组（95％）和I组（80％）明显升高（P＜0.01）.结论 肺功能正常的肥胖患者全身麻醉机械通气时,根据校正体重8 ml/kg设置潮气量是可行的.

Objective To evaluate the feasibility of using corrected body weight to set the tide volume （VT） for mechanical ventilation during general anesthesia in obese patients.Methods Sixty ASA physical status Ⅰ or Ⅱ obese patients,with a body mass index of 28-44 kg/m2,scheduled for elective extremity surgery under general anesthesia,were randomly divided into 3 groups （n =20 each）：VT based on actual body weight group （group A）,VT based on ideal body weight group （group Ⅰ）,and VT based on corrected body weight group （group C）.The pulmonary function of all patients was normal.The patients were endotracheally intubated and mechanically ventilated after induction of anesthesia.According to the corresponding body weight,the initial VT was set based on 8 ml/kg in each group （RR 15 bpm,I ∶ E =1 ∶ 2,FiO2 =100％）.At 10 min after start of mechanical ventilation,peak airway pressure （Ppeak）,airway plateau pressure （Pplat）,airwayresistance （Raw） were recorded.Arterial blood samples were collected at 30 min of mechanical ventilation for blood gas analysis and PaO2,PaCO2 and the patients requiring readjustment of VT （PaCO2 ＞ 45 mm Hg or ＜ 35 mm Hg） were also recorded.Results Compared with group A,PaCO2 was significantly increased and Ppeak,Pplat and Raw were decreased in I and C groups （P ＜ 0.01）.PaCO2 was significantly lower and Ppeak,Pplat and Raw were higher in group C than in group Ⅰ（P ＜ 0.01 or 0.05）.There were no patients requiring readjustment of VT in group C,however,95％ patients required readjustment of V＋ in group A and 80％ in group B.The percentage of patients requiring readjustment of VT was significantly higher in A and B groups than in group C （P ＜ 0.01）.Conclusion Corrected body weight based on 8 ml/kg can be used to set the Vr for mechanical ventilation during general anesthesia in obese patients with normal pulmonary function.