气管导管阻力变化对呼吸收缩压变异试验的影响

目的 研究气管导管阻力变化对呼吸收缩压变异试验(RSVT)的影响.方法 对20例患者进行预测液体反应的RSVT,试验运用3个连续改变的压力10、20、30 cm H2O(1 cm H2O=0.098 kPa)]控制呼吸,测定3个最低收缩压值并与相应的气道压力作图得到斜率(RSVT斜率).比较正常气管导管阻力和导管阻力增加两种情况下的RSVT斜率,气管导管阻力增加用在气管导管内插入Cooperdech支气管封堵导管来模拟.结果 在正常气管导管阻力时,导管阻力为(5.19±2.38)(cm H2O·s)/L,RSVT斜率为(0.39±0.21)mm Hg/cm H2O(1 mm Hg=0.133 kPa),3个不同控制压力水平(10、20、30 cm H2O)对应的潮气量分别为(461.5±95.9)、(891.5±149.8)和(1207.5±159.1)ml;在高气管导管阻力时,导管阻力为(8.77±1.64)(cm H2O·s)/L,RSVT斜率为(0.27±0.17)mm Hg/cm H2O,3个不同控制压力水平对应的潮气量显著降低,分别为(434.5±92.8)、(796.5±96.6)和(1097.5±68.4)ml,与正常气管导管阻力比较,差异均有统计学意义(P<0.05或<0.01).结论 气管导管阻力的增加会导致RSVT斜率的降低.

The impact of endotracheal tube's resistance on the respiratory systolic variation test

Objective To study the effect of endotracheal tube's resistance on the respiratory systolic variation test(RSVT).Methods The RSVT,a test to predict fluid responsiveness was performed in 20 patients.The test consisted of the delivery of three congecutive pressure-controlled breaths with incremental peak inspiratory pressures of 10,20 and 30 cm H2O(1 cm H2O=0.098 kPa).The minimal values of the systolic arterial pressure following each of these three breaths were measured and plotted against their respective airway pressures,producing the RSVT slope.RSVT slope were compared between normal airway resistance and increased resistance circumstances,and the latter was simulated by advancing a Cooperdech bronchial blocker into endotracheal tube.Results Under normal resistance,RSVT slope was(0.39±0.21) volumes were(461.5±95.9),(891.5±149.8)and(1207.5±159.1)ml,when peak inspiratory pressures of 10,20 and 30 cm H2O were dehvered.When bronchial blocker was advanced into endotrecheal tube, (0.27±0.17)mm Hg,cm H2O significantly(P<0.01),and tidal volumes decreased to(434.5±92.8), (796.5±96.6)and(1097.5±68.4)ml(P<0.05 or<0.01).Conclusion Changes in endotraeheal tube's resistance can distort the RSVT slope.