通过肺动态顺应性确定ARDS犬肺复张后最佳PEEP的研究

目的 观察肺复张后PEEP滴定过程中最佳肺氧合与最佳肺动态顺应性(Cdyn)的关系,探讨通过肺Cdyn确定最佳PEEP的方法.方法 静脉注射油酸复制犬ARDS模型,采用压力控制通气(PCV)实施肺复张.PEEP滴定从24cmH2O(T24)开始,每隔10min降低2cmH2O,当降低至6cmH2O(T6) 10min后,直接降至0cmH2O(T0).持续监测气道峰压(Ppeak),肺Cdyn,吸气末压力(EIP),并用Open Lung Tool软件观察趋势变化.在每阶段的末尾,抽动脉血行血气分析,采用吸气-呼气暂停方式测量肺静态顺应性(Cst).肺泡开始萎陷的PEEP水平根据氧合指数下降＞10％确定.结果 6只犬在PEEP为16cmH2O时氧合指数下降＞10％,而此时肺Cdyn最高,提示此时的PEEP水平为肺泡开始萎陷的水平,最佳PEEP应为该压力+2cmH2O,即18cmH2O.结论 在肺复张后PEEP滴定过程中,可以通过肺Cdyn的变化来判定肺泡萎陷的开始,从而确定最佳PEEP的水平.

Definition of optimal PEEP by dynamic compliance after lung recruitment maneuver in canine ARDS model

Objective To investigate the correlation between the optimal lung oxygenation and dynamic lung compliance (Cdyn) during positive end-expiratory pressure (PEEP) titration after lung recruitment maneuver, and explore the method for determining the optimal PEEP titration by Cdyn.Methods ARDS model was reproduced by intravenous injection of oleic acid into anesthetized dogs.Lung recruitment maneuver was performed by pressure-controlled ventilation(PCV).The PEEP titration was started from 24cmH2O(T24),and it was decreased by 2cmH2O every 10 minutes.After reaching 6cmH2O(T6) for 10 minutes, the PEEP was immediately adjusted to 0cmH2O(T0).Airway peak pressure(Ppeak),Cdyn and end-inspiratory pressure(EIP) were continually measured by Servo-i monitor,and the variation trends were observed with Open Lung Tool software.At the end of each stage,arterial blood was drawn for blood gas analysis,and static lung compliance was measured using inspiratory and expiratory pause manner.The PEEP at the time of beginning of lung collapse was defined as >10% decrease of oxygenation index.Results In all the 6 dogs,when PEEP= 16cmH2O,the oxygenation index decreased by more than 10%.Simultaneously,the lung compliance reached its peak value.This suggested that PEEP at this moment indicated the beginning of lung collapse. Therefore,the optimal PEEP should be 16cmH2O plus 2cmH2O, namely 18cmH2O. Conclusion During the titration of PEEP after lung recruitment maneuver,the beginning of lung collapse could be inferred from the Cdyn,thereby determining the optimal PEEP.