肺内外源性急性呼吸窘迫综合征实施俯卧位通气时间的选择

How to choose the duration of prone position ventilation in patients with acute respiratory distress syndrome caused by pulmonary or extrapulmonary diseases?

目的 通过观察俯卧位通气对肺内、外源性急性呼吸窘迫综合征 (ARDS)患者氧合、肺力学的影响 ,探讨实施俯卧位通气时间的选择。方法 对 9例早期肺内源性ARDS(A组 )、7例早期肺外源性ARDS(B组 )患者俯卧位通气 2h ,分别监测俯卧位通气前、通气 0 5h、2h时的氧合、肺力学的变化。观察俯卧位通气前及通气后 10min两组患者胸部CT影像学的变化。结果 A组患者俯卧位通气 0 5h时 ,氧合指数 [动脉血氧分压 (PaO2 ) /吸入氧浓度 (FiO2 ) ]较通气前无明显升高 ,通气 2h时PaO2 /FiO2 明显升高 (P <0 0 5 ) ;B组患者俯卧位通气 0 5h时PaO2 /FiO2 较通气前明显升高 (P<0 0 5 ) ,且 2h时仍维持较高水平。俯卧位通气 0 5h ,A组患者中仅有 1例对通气氧合反应良好 ,B组有 7例对通气氧合反应良好 (P =0 0 0 0 7) ;俯卧位通气 2h ,A组有 6例患者对通气氧合反应良好 ,B组有 6例对通气氧合反应良好 ,两组间差异无显著性 (P =0 392 )。A组患者俯卧位通气 2h后气道阻力明显下降 (P <0 0 5 )。俯卧位通气 10min后A组患者胸部CT显示肺实变区部分消失 ,B组则显示两肺原重力依赖区的肺实变迅速改善及新重力依赖区形成。结论 俯卧位通气可改善早期ARDS患者的氧合 ,肺外源性ARDS患者氧合改善迅速 ,但维持通气时间短 。

Objective To determine the different effect of prone position ventilation (PPV) in patients with acute respiratory distress syndrome(ARDS) resulting from a pulmonary cause (ARDSp) and that from an extrapulmonary cause (ARDSexp) on oxygenation, respiratory mechanics and hemodynamics To determine an appropriate duration of ventilation in the prone position in the two groups Methods Nine ARDSp patients and seven ARDSexp patients within 3 days of onset of ARDS were included in this study which were classified as two groups The patients were placed in prone position for 2 h The effect of different time (pre PPV, PPV 0 5 h, PPV 2 h) on oxygenation, respiratory mechanics and hemodynamics were observed Lung computerized tomography (CT) was obtained in both the supine position and 10 min after prone position Results Compared with pre PPV, in ARDSp,partial pressure of oxygen in artery(PaO 2)/inhaled oxygen concentration(FiO 2) was not increased after 0 5 h, and increased only after 2 h in the prone position (130 6±36 2 to 165 1±72 3, P <0 05) But in ARDSexp, PaO 2/FiO 2 was significantly increased after 0 5 h and 2 h in the prone position (116 5±55 0 to 163 2±46 4 and 182 7±87 7, P <0 05) After 0 5 h in the prone position the responding ratio of ARDSexp was higher than ARDSp (7/7 vs 1/9, P =0 0007) After 2 h, no significant difference of responding ratio was found between the two groups (6/7 vs 6/9, P =0 392) The changes of the PaO 2 were similar to the PaO 2/FiO 2 The PaCO 2 and the static respiratory system compliance(Cst ′rs) did not differ significantly between the prone position and the supine position in the two groups In ARDSp,the airway resistance was (10 8±1 4) cm H 2O·s -1 ·L -1 in the supine position, and it was significantly decreased after 2 h in the prone position (8 4±1 8) cm H 2O·s -1 ·L -1 ( P <0 05) Chest CT scans of ARDSp and ARDSexp patients showed markeddifference Conclusions PPV could be used to improve severe hypoxemia of ARDS It improved the PaO 2/FiO 2 ratio rapidly in ARDSexp, but in ARDSp the improvement took a longer time