比例辅助通气临床应用的方法学及疗效评价

摘要

目的　建立比例辅助通气（PAV）临床应用的方法，评价治疗慢性阻塞性肺疾病(COPD)急性发作期患者的疗效，并与压力辅助通气（PSV）比较。rn方法　选取10例COPD机械通气患者，分别采用吸气阻断法和脱逸法设定参数。每例随机先后采用PAV或PSV，PAV辅助水平分别设为80%、60%和40%。同时监测主观感受、血流动力学、氧动力学和呼吸力学指标。rn结果　吸气阻断法与脱逸法设定的参数有很好的相关性r=0.928（P<0.01）。PAV不同的辅助水平只影响吸气峰压、呼吸机及患者做功，对通气指标无显著影响(P>0.05)。对循环功能稳定者，两组的血流动力学指标无显著差异（P>0.05），氧合均保持在满意水平。在患者做功相同时，PAV组比PSV组潮气量有减小趋势（P>0.05），动脉血PaCO 2显著增高（P<0.05），吸气峰压显著减低（P<0.01）。rn结论　采用脱逸法设定参数简单可靠。PAV是安全有效的通气模式,人机协调性好。在做功相同时，PAV比PSV吸气峰压降低，根据患者的需要保持相应的通气量。%Objective To investigate the impact of proportional assist ventilation (PAV) on tolerance and breathlessness in ventilated chronic obstructive pulmonary disease (COPD), a nd to describe the patient-ventilator interaction, hemodynamic state, breathing pattern and work of breath during PAV and pressure support ventilation (PSV) . rnMethods Ten intubated COPD patients on weaning from mechanical ventilation were studied . Elastance and resistance were measured by both the inspiratory-hold techniqu e during a brief period of volume control ventilation and runaway technique duri ng PAV. Each assistance level of PAV (80%, 60% and 40%) and PSV was selected ra ndomly. Patients' response, hemodynamics, blood gas and lung mechanics were mon itored. rnResults Tidal volume and respiratory rate didn't change in a consistent manner as the le vel of assist was decreased (P>0.05). With the level of assist increasing, peak inspiratory pressure was increasing significantly (P<0.05), while pat ients' work of breath had the tendency to decrease (P<0.05). A significant difference in the Borg Category Scale was observed between PAV and PSV (0.50[ 1.50] vs 0.75[2.00], P<0.05) at the same degree of respiratory muscle unloading. PaCO2 was significantly higher on PAV (54[23]mmHg) than on PSV (48[23]mmHg) (P<0.05). Peak inspiratory pressure on PAV was sign ificantly lower than on PSV (16±4cmH2O vs 21±3cmH2O, respectively , P<0.05). Hemodynamics and oxygenation remained unchanged.rnConclusions PAV is a feasible method for supporting ventilator-dependent patients and was w ell tolerated. It can improve the breathing pattern and reduce inspiratory effo rt. At the same degree of respiratory muscle unloading, PAV can be implemented at much lower peak inspiratory pressure than PSV. It can also apply proportiona l pressure support according to the patients' ventilatory demand.