不同体位下不同模式机械通气对新生儿心脏直视术后急性肺损伤的影响

Effect of prone or spine position on mechanically ventilated neonates after cardiac surgery with acute lung injury

目的 探讨不同体位下压力支持通气（PSV）和神经调节辅助通气（NAVA）对新生儿心脏直视术后急性肺损伤（ALI）的影响.方法 研究纳入15例危重先天性心脏病急诊术后发生ALI的新生儿,男12例,女3例,年龄2～28（15±9）d,体重2.2～4.3（3.5±0.6）kg.采用交叉对照研究方式,先给予压力调节容量控制通气（PRVC）至血液动力学稳定（PRVC-base）,然后随机进行仰卧位PSV（PSV-SP）、仰卧位NAVA（NAVA-SP）、俯卧位PSV（PSV-PP）和俯卧位NAVA（NAVA-PP）机械通气,各模式持续60 min.记录心率、收缩压和中心静脉压等血液动力学指标,吸气峰压（PIP）、平均气道压（MAP）、呼吸频率、潮气量（VT）和分钟通气量（MV）等呼吸力学指标,动脉血二氧化碳分压（PaCO2）、氧合指数、动脉血气分析指标,以及膈肌电信号（Eadi）和非同步指数（AI）.结果 不同模式机械通气时患儿血液动力学指标均稳定.不同体位PSV和NAVA时PIP、MAP和VT差异无统计学意义,均低于PRVC-base时（均P＜0.05）;呼吸频率在俯卧位PSV、NAVA时快于PRVC-base和仰卧位PSV、NAVA时（均P＜0.05）;MV无明显变化.PSV-SP、PSV-PP、NAVA-SP和NAVA-PP时PaCO2均无明显变化,处于正常水平;氧合指数[分别为（272±76）、（308±90）、（347±84）和（365±87）mm Hg（1 mm Hg=0.133 kPa）]均明显高于PRVC-base时[（200±60）mm Hg,均P＜0.01],NAVA-PP时氧合指数高于PSV-SP时（P＜0.05）.NAVA-PP时Eadi谷值低于PSV-SP时[（0.2±0.1）μV比（0.5±0.2）μV,P＜0.05].NAVA-SP和NAVA-PP时AI均为0,明显低于PSV-SP时[（21.5±4.8）%,P＜0.05]和PSV-PP时[（22.4±3.4）%,P＜0.05].结论 心脏直视术后发生ALI的新生儿行机械通气时,俯卧位条件下采用NAVA模式在保持人机同步性方面优势明显,有利于改善患儿氧合状况.

Objective To compare the efficacy and safety ventilated with pressure support ventilation （ PSV ） or neurally adjusted ventilatory assist （ NAVA ） in neonates undergoing open-heart surgery with acute lung injury （ALI） in spine and prone positions. Methods Fifteen neonates with a mean age of （15 ±9） days and a mean weight of （3.5 ±0. 6） kg underwent open-heart surgery with ALI from July to December in 2009 were enrolled in this study. After hemodynamic stabilization ventilated with pressure regulated volume control （PRVC-base）, all cases were ventilated with PSV and NAVA both in spine （SP）and prone （PP） positions for 60 minutes in a randomized crossover trial respectively. The hemodynamics,blood gas analysis, airway pressure, electrical activity of diaphragm （EAdi） and asynchrony index （AI）during every mode were recorded. Results The heart rate, systolic blood pressure and central venous pressure were stable in every mode. The peak inspiratory pressure and mean airway pressure in every mode had no significant difference but were significantly lower than in PRVC-base either in spine or prone position. The respiratory rate in PSV and NAVA with prone position was more rapid than in spine position and in PRVC-base （ P 〈 0. 05 ）. But there was no significant difference in minute ventilation （ MV ） for each mode. The oxygenation index was higher in NAVA or PSV in both positions versus PRVC-base [（200 ±60）mm Hg in PRVC-base, （272 ±76） mm Hg in PSV-SP, （308±90） mm Hg in PSV-PP, （347 ±84）mm Hg in NAVA-SP and （365 ±87） mm Hg in NAVA-PP respectively, P 〈0. O1]. The oxygenation index was significantly higher in NAVA-PP than in PSV-SP （P 〈0. 05 ） while PaCO2 was in normal range and had no significant difference for any mode. The minimal EAdi in NAVA-PP was significant lower than that in PSV-SP [（0.2±0. 1） μV vs （0.5 ±0.2） μV, P〈0.05]. The AI of NAVA either in spine or in prone position was 0. It was significantly lower than that in PSV-SP [（21.5 ±4. 8 ）%, P 〈0. 01] and PSV-PP [（22.4 ± 3.4 ） %, P 〈 0. 01]. Conclusion Especially in a prone position, NAVA demonstrates a better synchrony in ALI neonates after cardiac surgery. It helps to provide a better oxygenation for the patients.