控制性肺膨胀对急性呼吸窘迫综合征肺静态顺应性曲线低位转折点的影响

Effects of sustained inflation on the pressure of lower inflection point in static pulmonary pressure volume curve with acute respiratory distress syndrome

目的 :探讨控制性肺膨胀 (SI)对急性呼吸窘迫综合征 (ARDS)肺静态顺应性曲线低位转折点压力(Pinf)的影响。方法 :30只家兔利用肺泡灌洗法建立 ARDS模型 ,并随机分为 SI组和非 SI组 ,观察 SI后 2小时动物的 Pinf、肺气体交换和肺机械力学特征改变。结果 :SI组动物 SI前 Pinf为〔(0 .90± 0 .14 ) k Pa,1k Pa=10 .2 0 cm H2 O〕,SI 2小时后 Pinf降到 (0 .6 1± 0 .14 ) k Pa(P=0 .0 2 0 ) ;非 SI组机械通气 2小时前后 Pinf无明显改变 ,P>0 .0 5。 SI组动物机械通气 2小时后动脉血氧分压 (Pa O2 )和氧饱和度 (Sa O2 )分别为 (2 4 .2 0±8.79) k Pa(1k Pa=7.5 m m Hg)和 0 .96 7± 0 .0 2 4 ,显著高于非 SI组〔分别为 (10 .80± 1.13) k Pa和 0 .76 8±0 .0 76 ,P<0 .0 5〕。 SI组动物机械通气 2小时后动态肺顺应性 (Cydn)为 (12 .2 4± 1.5 3) ml/k Pa,显著高于非 SI组〔(9.80± 0 .82 ) ml/k Pa〕。结论 :SI具有促进肺泡复张、降低 Pinf水平的效应 ,实施 SI后应重新调整呼气末正压 (PEEP)水平。

Objective:To observe the effect of sustained inflation(SI) maneuver on the pressure of lower inflection point in static pressure volume curve(Pinf) in rabbits with acute respiratory distress syndrome(ARDS).Methods:SI was applied at pressures of 6 times of mean airway pressure(Pm) for 20 seconds on saline lavaged anesthetized rabbits.Animals were divided into SI group( n =15) and non SI group( n =15).Pinf+0 196 kPa(1 kPa=10 20 cmH 2O) was expressed as positive endexpiratory pressure(PEEP).Hemodynamics,pulmonary mechanics,Pinf,and gas exchange were observed 2 hours after applying SI.Results:In SI group,Pinf was(0 61±0 14) kPa(1 kPa=10 20 cmH 2O)at 2 hours after applying SI,which was significantly higher than Pinf prior to SI〔(0 90±0 14) kPa, P =0 020〕.There was no difference in Pinf value in nonSI group between 0 and 2 hours after ventilation.Partial pressure of arterial oxygen(PaO 2) and arterial oxygen saturation were improved in SI group.At 2 hours after applying SI,PaO 2 and SaO 2 were(24 20±8 79) kPa( 1 kPa = 7 5 mmHg ) and 0 967±0 024 respectively in SI group,which were markedly higher than those in nonSI group〔(10 80±1 13)kPa and 0 768±0 076, P <0 05〕 At 2 hours after applying SI,dynamic pulmonary compliance(Cdyn) in SI group〔(12 24±1 53) ml/kPa〕was increased markedly,as compared with Cdyn in non SI group〔(9 80±0 82) ml/kPa, P <0 05〕.Conclusions:SI can impove alveolar recruitment and decrease the level of Pinf.The PEEP level should be changed according to the change of Pinf.