急性呼吸窘迫综合征肺复张后正常通气容积比例决定动脉血氧合

隆云; 刘大为; 周翔; 崔娜

doi:10.3969/j.issn.1674-9081.2013.03.017

急性呼吸窘迫综合征肺复张后正常通气容积比例决定动脉血氧合

Arterial Oxygenation was Determined by the Volume Partition of Normal Aeration Region after Sustained Inflation in Acute Respiratory Distress Syndrome

摘要

摘要:
目的研究急性呼吸窘迫综合征时不同肺复张手法的肺内影像学特征及其与动脉血气的关系。
方法在10只肺泡灌洗致急性呼吸窘迫综合征的新西兰家兔中, 应用动态肺部CT扫描, 监测并使用Image-J软件分析随气道压力递增和递减时肺内气体容积及分布的变化。然后分别以5种不同开放肺泡的压力和维持肺泡开放的呼气末正压(positive end-expiratory pressure, PEEP)水平进行控制性肺膨胀(sustained inflation, SI), 测量SI后2 min及20 min时的动脉血气。分析不同压力水平下的影像学特征及其与动脉血气的关系。
结果在使用不同气道压力进行SI后应用相同PEEP水平进行通气时, 发现肺复张后2 min与20 min时的PaO₂均随SI压力的增加而明显增加(P < 0.05)。PaO₂与不同气道压力下正常通气容积比例呈正相关(r=0.597, P=0.001), 与通气不良容积比例(r=-0.592, P=0.001)和塌陷容积比例(r=-0.475, P=0.012)呈负相关, 而与过度通气容积比例无关(r=0.202, P=0.311)。在使用相同气道压力进行SI后应用不同PEEP进行通气时, 发现肺复张后2 min时的不同PEEP水平下PaO₂差异无统计学意义(P>0.05);而在通气20 min时, 高PEEP水平下PaO₂明显高于低PEEP水平(P < 0.05)。PaO₂与正常通气容积比例呈正相关(r=0.635, P=0.000), 与通气不良容积比例(r=-0.609, P=0.000)和塌陷容积比例(r=-0.544, P=0.002)呈负相关, 而与过度通气容积比例无关(r=0.058, P=0.762)。
结论完全肺复张需要较高的开放肺泡和维持肺泡开放的气道压力。肺复张后正常通气区域容积比例决定PaO₂。

Abstract:
Objective To analyze the correlation of arterial blood gas with pulmonary CT scan image after sustained inflation (SI) with the attempt to explore the optimal recruitment maneuvers (RMs) in acute respiratory distress syndrome.
Methods Dynamic pulmonary CT scan was performed to monitor the intrapulmonary gas volume and distribution during increment and decrement of airway pressure gradually in 10 warm-saline-lavaged New Zealand rabbits. CT scan was analyzed by Images-J software. In order to explore optimal airway pressure for opening lung and optimal positive end-expiratory pressure (PEEP) for maintaining lung open, five different SIs were implemented individually and randomly, and rabbits' arterial blood gases were measured in 2 and 20 minutes after every SI. Pulmonary CT scan and PaO₂ under different airway pressure were combined to be analyzed.
Results After different airway pressure of SI and equal PEEP ventilation, PaO₂ was increased accompanied with airway pressure of SI both in 2 and 20 minutes after RMs (P < 0.05). When PaO₂ was combined with CT images, we found PaO₂ was positively correlated with the volume partition of normal aeration region (r=0.597, P=0.001), negatively correlated with the insufficient aeration region (r=-0.592, P=0.001) and nonaeration region (r=-0.475, P=0.012), while not correlated with the overdistension region (r=0.202, P=0.311). While after equal airway pressure of SI and different PEEP ventilation, the difference of PaO₂ was not significant in 2 minutes after RMs (P>0.05), and PaO₂ was increased accompanied with PEEP in 20 minutes (P < 0.05). In this situation, we found PaO₂ was positively correlated with the volume partition of normal aeration region (r=0.635, P=0.000), negatively correlated with the insufficient aeration region (r=-0.609, P=0.000) and nonaeration region (r=-0.544, P=0.002), while not correlated with the overdistension region (r=0.058, P=0.762).
Conclusions High airway pressure is needed for opening up the lung and keeping the lung open. Arterial oxygenation is determined by the volume partition of normal aeration region after SI.

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