目的 探讨吸呼比1:1(I:E=1:1)对侧卧位单肺通气患者肺顺应性和肺内分流的影响。方法 选择46例年龄20-65周 岁，ASAI-II级，全麻机械通气胸腔镜下行肺叶切除或食管癌根治术的患者，随机分为两组(n=23)，对照组(C组， I:E=1:2)和实验组(E组，I:E=1:1)。机械通气期间在单肺通气后开始调整吸呼比。取平卧双肺通气后15min(t0)、 侧卧单肺通气后30min(t1)、60min(t2)三个时间点，检测动脉血气并记录呼吸参数，计算肺顺应性及肺内分流率。 结果 两组气道峰压、气道平台压及肺内分流率与t0相比，均在t1、t2时明显增加(P<0.001)；而动脉氧合、肺顺应 性均有所下降(P<0.001)，差异有统计学意义。与C组相比，E组的气道峰压和气道平台压明显降低(P<0.001)，肺顺 应性提高(P<0.001)，肺内分流减少(P=0.021)，动脉血氧分压(P=0.034)和血氧饱和度(P=0.03)明显增加，差异均 具有统计学意义。结论 侧卧位单肺通气期间，采用I:E=1:1较I:E=1:2，有利于降低气道峰压及气道平台压，提高 肺动态顺应性；减少肺内分流，相对改善动脉氧合。

Objective To evaluate the effect of lung compliance and intrapulmonary shunt by increasing the inspiratory time during one lung ventilation(OLV). Methods Forty-six age 20-65 years of age, ASA ⅠorⅡgrade patients, scheduled for selective thoracoscopic lobectomyunder lateral decubitus position were randomy divided into two groups with 23 each:C and E groups. After one lung ventilation,the inspiratory-to-expiratory ratio was adjusted during mechanical ventilation.Arterial blood gas analysis and respiratory parameters was determined after two lung ventilation (TLV) 15min(t0) and 30min(t1), 60min(t2) after OLV. Intrapulmonary shunt (Qs/Qt) and lung compliance(Cdyn) were calculated. Results Two groups Peak airway pressure (Ppeak), airway plateaupressure(Pplat) and Qs/Qt increased in t1 and t2 when compared with t0(P<0.001). PaO2, SaO2 and Cdyn decreased(P<0.001). Ppeak, Pplat(P<0.001) and Qs/Qt (P=0.021) decreased obviously in t1 and t2 in group E when compared with group C. Group E had a better PaO2(P=0.034), SaO2(P=0.03) and Cdyn(P<0.001) in t1 and t2. The difference was all statistically significant. Conclusion In the lateral position, using I:E=1:1 compared with I:E=1:2, it is advantageous to reduce the Ppeak, Pplat and Qs/Qt, improve the dynamic compliance of the lung.To a certain extent, it's improving arterial oxygenation.