A-Meguid Mohamed Essam, el-Din Mansour Emad, Abdullah Khaled M
King Khalid University Hospital, King Saud University, Riyadh, KSA.
Middle East J Anaesthesiol. 2006 Oct;18(6):1059-70.
This study aimed at evaluating the effect of application of different patterns of positive ventilatory pressure either during or after cardiopulmonary bypass (CPB), on lung functions.
30 patients undergoing coronary artery revascularisation under the management of CPB were randomly allocated into 3 groups. Group I (VCM) 10 patients were subjected to manual vital capacity manoeuvre (VCM) before weaning off the CPB. Group II (CPAP) 10 patients were subjected to continuous positive airway pressure (CPAP) of 10 cmH2O during CPB. Group III (PEEP) 10 patients were subjected to positive end expiratory pressure (PEEP) of 7 cmH2O after weaning off the CPB. Measurements included the PO2, PCO2, together with derived calculated parameters as the alveolar-arterial oxygen difference [P (A-a) DO2] and shunt fraction, as well as the dynamic lung compliance being recorded directly from the anesthetic and ventilatory equipments. All readings were taken on closed chest and on FiO2 of 0.5. Intraoperative anesthetic and surgical data as well as postoperative extubation time and length of ICU stay were also evaluated.
Statistical analysis of ventilatory parameters showed no significant differences for both PO2 and PCO2 in between the studied groups. Alveolar-Arterial oxygen difference mean values were comparable in the 3 studied groups. The mean values of intrapulmonary shunt fraction showed a significant difference in relation to the baseline values in Group I (VCM) and Group III (PEEP) at 30 minutes after ICU admission and 4 hours post CPB with estimated P value < 0.01 and < 0.05 respectively, while in Group II (CPAP) mean values started to be significant after chest closure with a P value < 0.05, but there was no significant intergroup differences with a P value > 0.01. Dynamic lung compliance mean values showed no intergroup statistical significance.
Maintenance of ventilatory parameters was achieved in all the positive pressure ventilatory methods applied, either being applied during or after CPB.
本研究旨在评估在体外循环（CPB）期间或之后应用不同模式的正压通气对肺功能的影响。
30例接受CPB管理下冠状动脉血运重建的患者被随机分为3组。第一组（VCM）10例患者在脱离CPB前进行手动肺活量操作（VCM）。第二组（CPAP）10例患者在CPB期间接受10 cmH₂O的持续气道正压（CPAP）。第三组（PEEP）10例患者在脱离CPB后接受7 cmH₂O的呼气末正压（PEEP）。测量包括PO₂、PCO₂，以及作为肺泡 - 动脉氧分压差[P（A - a）DO₂]和分流分数的派生计算参数，还有直接从麻醉和通气设备记录的动态肺顺应性。所有读数均在封闭胸腔和FiO₂为0.5的情况下获取。还评估了术中麻醉和手术数据以及术后拔管时间和ICU住院时间。
通气参数的统计分析显示，研究组之间的PO₂和PCO₂均无显著差异。3个研究组的肺泡 - 动脉氧分压差平均值相当。肺内分流分数的平均值在ICU入院后30分钟和CPB后4小时时，与第一组（VCM）和第三组（PEEP）的基线值相比有显著差异，估计P值分别<0.01和<0.05，而在第二组（CPAP）中，平均值在关胸后开始显著，P值<0.05，但组间差异不显著，P值>0.01。动态肺顺应性平均值无组间统计学意义。
在所应用的所有正压通气方法中，无论是在CPB期间还是之后应用，均实现了通气参数的维持。
