心脏手术后患者撤机时比例辅助通气的效果

Efficacy of proportional assist ventilation in weaning the patients from ventilator after cardiac surgery

目的评价心脏手术后患者撤机时比例辅助通气(PAV)的效果。方法46例心脏手术后患者,年龄18～72岁,体重40～65 kg,ASAⅠ或Ⅱ级。测得呼吸系统弹性阻力(Ers)及气道阻力(Rrs),先按80％辅助比例行PAV(PAV80),以PAV80时潮气量(VT)确定压力支持通气(PSV)的目标VT,再随机先后予PAV80、PSV及持续气道正压(CPAP)各通气30 min,观察每种模式下呼吸方式指标[VT、呼吸频率(RR)、分钟通气量(VE)、浅快呼吸指数(RSBI)、吸气时间占呼吸周期比(Ti/Ttot)、气道峰压(PIP)、平均气道压(Paw)、呼气末正压(PEEP)、内源性呼气末正压(PEEPi)];呼吸作功指标[(压力-时间积分(PTP)、患者呼吸功(WOBp)、呼吸机呼吸功(WOBv)];血液动力学指标[心率(HR)、平均动脉压(MAP)、中心静脉压(CVP)]及动脉血气指标的变化。结果与CPAP时比较,PAV80、PSV时WOBv、PIP、Paw、VT、PaO2、SaO2升高,PTP、WOBp、WOBp／WOBt、RR、RSBI、Ti／Ttot、pH、PaCO2降低(P<0．05或0．01);与PSV时比较,PAV80时PTP、WOBp和WOBp／WOBt升高(P<0．01),PIP、Paw降低(P<0．05)。PAV80与PSV间PaO2、SaO2、MAP、HR和CVP差异无统计学意义。结论PAV是适宜于心脏手术后患者撤机的一种通气模式。

Objective To evaluate the efficacy of proportional assist ventilation（PAV） in weaning the patients from ventilator after cardiac surgery as compared with pressure support ventilation （PSV） and continuous positive airway pressure （CPAP） in terms of respiratory and homodynamic parameters and gas exchange. Methods Forty-six ASA Ⅰ or Ⅱ patients aged 18-72 yrs, weighing 40-65 kg were studied immediately after cardiac surgery including valve replacement and CABG. As soon as the patients regained consciousness and resumed spontaneous breathing, they were ventilated by PAV80, PSV and CPAP consecutively in randomized order. Each mode lasted for30 minutes. VT, RR, peak inspiratory pressure （PIP）, average airway pressure （Paw）, PEEP, work of breathing （WOB）, HR, MAP, CVP, and blood gases were monitored. Results During CPAP VT, PIP, Paw, PaO2 and SaO2 were significantly decreased while RR, rapid-shallow-breathing index （RSBI）, Ti/Ttot, pressuretime product （PTP）, patient＇s work of breathing （WOBp）, pH and PaCO2 were significantly increased （P 〈 0.01 ） as compared with PAV80 and PSV modes. PAV80 resulted in a decrease in PIP and Paw and an increase in PTP as compared with PSV. There was no difference in arterial blood gases （ PaO2, PaCO2 ） and MAP, HR and CVP between PAV80 and PSV modes. Conclusion PAV is a mode of choice in weaning the patients from ventilator after cardiac surgery.