控制性肺膨胀治疗急性呼吸窘迫综合征家兔的最佳压力选择

目的　探讨实施控制性肺膨胀 (SI)治疗急性呼吸窘迫综合征 (ARDS)的最佳复张压力。方法　采用肺泡灌洗法建立重度ARDS家兔模型 ,以 1～ 6倍的平均气道压 (Pm)作为实施SI的压力 ,屏气时间 2 0s。在SI前、SI期间及SI后 2min和 5min监测家兔血流动力学、肺力学、肺气体交换和肺损伤指标。以改善氧合和肺容积最显著、不加重肺损伤、同时对血流动力学影响最小的压力为最佳压力。结果　SI的压力达到 3Pm 以上时 ,家兔动脉血氧分压 (PaO2 )和动脉血氧饱和度明显提高。 5Pm 和6Pm 时SI前后的PaO2 差值 (ΔPaO2 )分别为 (6 5± 40 )mmHg(1mmHg =0 133kPa)和 (5 2± 2 5 )mmHg ,显著高于 1Pm(- 5± 4)mmHg ,P <0 0 5 ]。 5Pm SI时的动态肺顺应性增加最明显 ,达 (3 0 6± 0 2 4)ml/cmH2 O ,明显高于SI前的水平 (1 0 9± 0 18)ml/cmH2 O ,P <0 0 5 ]。 5Pm 时SI前后肺容积改变最显著 ,达到 (4 4 0± 3 1)ml/kg,明显高于 1Pm(8 3± 0 7)ml/kg ,P <0 0 5 ]。未实施SI的ARDS家兔肺损伤评分为 6 10± 0 77,5Pm 时的肺损伤评分显著降低 (4 4 0± 1 6 6 ,P <0 0 1)。 6Pm 时则导致肺泡过度膨胀 ,加重肺损伤。随着SI的压力增加 ,家兔的平均动脉血压显著降低。结论　重度ARDS家兔实施SI的最佳压力是 5Pm(2 5～

The optimal pressure of sustained inflation for alveolar recruitment in acute respiratory distress syndrome rabbit model

OBJECTIVE: To determine the optimal pressure of sustained inflation (SI) in treatment of acute respiratory distress syndrome (ARDS). METHODS: SI was applied at pressures of 1 approximately 6 times of mean airway pressure (P(m)) for 20 s on saline alveoli-lavaged anesthetized rabbits. Hemodynamics, pulmonary mechanics and gas exchange were observed before, during, and 2 min, 5 min after applying SI. Lung histology was observed after the experiment. RESULTS: When the pressure of SI was higher than 3P(m), partial pressure of arterial oxygen (PaO(2)) and arterial oxygen saturation were improved. The difference of PaO(2) before and during SI were (65 +/- 40) mm Hg and (52 +/- 25) mm Hg respectively in the 5P(m) and 6P(m) group, being significantly higher than that in the 1P(m) group (-5 +/- 4) mm Hg, P < 0.05]. After SI, dynamic pulmonary compliance (C(dyn)) in the 5P(m) group (3.06 +/- 0.24) ml/cm H(2)O] was increased markedly, as compared with C(dyn) before SI (1.09 +/- 0.18) ml/cm H(2)O, P < 0.05]. SI with 5P(m) resulted in immediate significant increase in lung volume (44.0 +/- 3.1) ml/kg in the 5P(m) group, (8.3 +/- 0.7) ml/kg in the 1P(m) group]. Histologically, Smith lung injury score was 4.40 +/- 1.66 in the 5P(m) group, which was less than that in the group of ARDS model 6.10 +/- 0.77. SI with 6P(m) led to alveolar overdistention. With the increasing of SI pressure, mean arterial pressure decreased markedly. CONCLUSION: 5P(m) (25 approximately 35 cm H(2)O) may be the optimal pressure of SI in rabbits with severe ARDS.