Feasibility of using corrected body weight to set tide volume for mechanical ventilation during general anesthesia in obese patients / 中华麻醉学杂志

ABSTRACT

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.