Optimal PEEP for volume-controlled ventilation in patients undergoing surgery with general anesthesia: pulmonary electrical impedance tomography monitoring / 中华麻醉学杂志

ABSTRACT

Objective To determine the optimal positive end-expiratory pressure (PEEP) for volume-controlled ventilation using pulmonary electrical impedance tomography in the patients undergoing surgery with general anesthesia.Methods Fifty patients of both sexes,aged 18-64 yr,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,with body mass index of 18.5-28.0 kg/m2,scheduled for surgery for ureteral calculi under general anesthesia,were enrolled in this study.The patients were tracheally intubated after anesthesia induction and mechanically ventilated in volume-controlled mode,with tidal volume 6 ml/kg,mean arterial pressure was recorded at 3 min of ventilation and served as the baseline value,and then PEEP was increased with an increment of 3 cmH2O every 3 min until PEEP reached 15 cmH2 O.The percentage of dorsal pulmonary ventilation and peak airway pressure were recorded at 3 min of ventilation with different PEEPs.When the decrease in mean arterial pressure was more than 20％ of the baseline value during ventilation,deoxyepinephrine 0.1 mg was injected intravenously,and the consumption of deoxyepinephrine was recorded within 3 min of ventilation with different PEEPs.Results Peak airway pressure was gradually increased with the increase of PEEP (P＜0.05),the percentage of dorsal pulmonary ventilation was gradually increased when PEEP was 6 cmH2O (P＜ 0.05),and the consumption of deoxyepinephrine was gradually increased when PEEP was 15 cmH2O (P＜0.05).Conclusion The optimal PEEP is 12 cmH2O during volume-controlled ventilation with tidal volume of 6 ml/kg in the patients undergoing surgery with general anesthesia.