体外循环下冠状动脉旁路移植手术早期呼吸力学变化

Early Changes of Respiratory Dynamics in Patients Undergoing Coronary Artery Bypass Grafting under the Cardiopulmonary Bypass

目的研究体外循环(cardiopulmonary bypass,CPB)下冠状动脉旁路移植手术(coronary artery bypass graft-ing,CABG)早期呼吸力学指标的变化。方法以25例全身麻醉、中低温CPB下行单纯CABG术患者为研究对象。测定开胸前、转流前、转流后、关胸后气道峰压、气道阻力及胸肺顺应性等呼吸力学指标。转流前后血气分析,计算肺泡-动脉氧压差(alveolar-arterial oxygen difference,A-aDO2)。结果CPB前后相比,气道峰压[从(16.9±2.8)cmH2O到(17.6±2.7)cmH2O,P<0.01,1 cmH2O=0.098 kPa]及气道阻力[从(7.8±1.6)cmH2O/(L.s)到(8.5±1.7)cmH2O/(L.s),P<0.01]明显升高,胸肺顺应性[从(64.9±7.3)ml/cmH2O到(62.1±6.9)ml/cmH2O,P<0.01]明显降低。A-aDO2在CPB后明显升高,从(159.2±61.0)mmHg到(203.5±25.4)mmHg(P<0.05,1 mmHg=0.133 kPa)。关胸后呼吸力学指标与开胸前相比都有明显的变化,胸肺顺应性降低18%(P<0.01),气道峰压及气道阻力分别升高5%(P<0.01)及10%(P<0.01)。转流时间与CPB前后的A-aDO2的变化率呈正相关关系(r=0.63,P<0.01)。结论CPB下CABG时开胸及体外循环影响早期呼吸力学的变化,而且CPB时间与肺换气功能损伤程度有密切关系。

Objective To observe the early changes of respiratory dynamics in patients undergoing coronary artery bypass grafting （CABG） under cardiopulmonary bypass （CPB）. Methods On 25 cases undergoing CABG under general anesthesia, CPB was accomplished with systemic mild hypothermia and local myocardial deep hypothermia. The changes of respiratory function [peak inspiratory pressure （PIP）, airway resistance （Raw） and dynamic compliance （Cdyn）] before opening chest, pre-CPB and post CPB,and after closing chest were monitored. Arterial blood gas specimens were sampled to make blood gas analysis before and after CPB. The PaO2 and PaCO2 were used to calculate the alveolar-arterial oxygen difference （A-aDO2）. Results PIP was increased from （16.9±2.8） cmH2Oto （17.6±2.7） cmH2O （P〈0.01） and Raw from （7.8±1.6） cmH2O/ （L · s） to （8.5±1.7） cmH2O/（L · s） （P〈0.01）, while Cdyn was decreased from （64.9±7.3） ml/cmH2O to （62. 1±6.9） ml/cmH2O （P〈0.01） significantly before and after CPB. A-aDO2 was increased significantly from （159.2±61.0） mmHg to （203.5 ± 25.4） mmHg （P〈0.05） after CPB. Respiratory dynamics were changed significantly before opening chest and after closing chest. Cdyn was increased by 18% （P〈0.01）, PIP and Rar decreased by 5% （P〈0.01） and 10% （P〈0.01） respectively. The time of CPB and A-aDO2 revealed a positive correlation （r=0.63, P〈0.01）. Conclusion Opening chest and CPB had effects on the changes of respiratory dynamics in patients undergoing CABG under the CPB. The time of CPB was closely related to the injury of lung ventilation.