[应激指数与急性呼吸窘迫综合征犬肺复张及气体交换的关系]

[Relationship of stress index with lung recruitment and gas exchange in dogs with acute respiratory distress syndrome].

作者信息

Qiu Hai-bo, Chen Yong-ming, Yang Yi, Shen Ju-fang, Li Jia-qiong, Wu Bin, Li Na

机构信息

Department of Critical Care Medicine, Zhong-da Hospital and School of Clinical Medicine, Southeast University, Nanjing 210009, China.

出版信息

Zhonghua Jie He He Hu Xi Za Zhi. 2006 Aug;29(8):554-7.

PMID:17074271

Abstract

OBJECTIVE

To determine the relationship of stress index with lung recruitment and gas exchange in dogs with acute respiratory distress syndrome (ARDS).

METHODS

The ARDS model was induced by infusion of oleic acid intravenously in anesthetized dogs. During volume control ventilation with constant inspiratory flow, the pressure-time (P-t) curve was fitted to a power equation: P = a.time(b)+c, where coefficient b (stress index) describes the shape of the curve: b = 1, straight curve; b < 1, progressive increase in slope; and b > 1, progressive decrease in slope. Tidal volume (V(T)) was 6 ml/kg, and positive end-expiratory pressure (PEEP) was set to obtain a b value between 0.9 and 1.1 before (b = 1) and after (b = 1 after recruiting maneuver) application of a recruiting maneuver (RM). PEEP was changed to obtain 0.6 < b < 0.8 and 1.1 < b < 1.3. Experimental condition sequence was random. Recruited volume (RV) was measured by static pressure-volume curve method. Hemodynamics, pulmonary mechanics and gas exchange were observed at the same time.

RESULTS

At b = 1 without RM, the PEEP was (5.0 +/- 3.0) cm H2O, the RV was (27 +/- 15) ml, and the RV increased to (166 +/- 84) ml significantly at b = 1 after RM [PEEP (10.8 +/- 2.3) cm H2O (1 cm H2O = 0.098 kPa), q = 3.18, P < 0.01]. At 1.1 < b < 1.3 after RM, the PEEP was (16.8 +/- 1.1) cm H2O and the RV was (262 +/- 57) ml, which was higher than that at b = 1 after RM (q = 2.54, P = 0.023). At 0.6 < b < 0.8 after RM, the PEEP was (5.6 +/- 2.2) cm H2O and the RV was lower than that at b = 1 after RM (q = 2.85, P = 0.013). The partial pressure of oxygen in arterial blood (PaO2) in b = 1, 0.6 < b < 0.8 and 1.1 < b < 1.3 after RM were (319 +/- 49) mm Hg (1 mm Hg = 0.133 kPa), (246 +/- 57) mm Hg and (314 +/- 27) mm Hg respectively, which was higher than the PaO2 at b = 1 without RM [(153 +/- 64) mm Hg, all q = 2.81, all P < 0.05]. The PaO2 at 0.6 < b < 0.8 was lower than that at b = 1 after RM (q = 2.81, P = 0.005), while there was no significant difference between the PaO2 at 1.1 < b < 1.3 and that at b = 1 after RM. The peak airway pressure and plateau pressure at 1.1 < b < 1.3 were higher than those at b = 1 after RM (q = 6.02, 5.72, all P < 0.05).

CONCLUSION

In the b = 1 after RM, there were better PaO2 and lower airway pressure, suggesting that b = 1 after RM may be a good indicator for PEEP titration.

摘要

目的

确定应激指数与急性呼吸窘迫综合征（ARDS）犬肺复张及气体交换之间的关系。

方法

通过静脉注射油酸在麻醉犬中诱导建立ARDS模型。在恒定吸气流量的容量控制通气期间，将压力-时间（P-t）曲线拟合为幂方程：P = a·time(b)+c，其中系数b（应激指数）描述曲线形状：b = 1，曲线为直线；b < 1，斜率逐渐增加；b > 1，斜率逐渐减小。潮气量（V(T)）为6 ml/kg，呼气末正压（PEEP）设置为在应用肺复张手法（RM）前（b = 1）和应用后（RM后b = 1）获得0.9至1.1之间的b值。改变PEEP以获得0.6 < b < 0.8和1.1 < b < 1.3。实验条件顺序是随机的。通过静态压力-容量曲线法测量复张容积（RV）。同时观察血流动力学、肺力学和气体交换。

结果

在无RM时b = 1时，PEEP为（5.0±3.0）cm H₂O，RV为（27±15）ml，在RM后b = 1时RV显著增加至（166±84）ml [PEEP（10.8±2.3）cm H₂O（1 cm H₂O = 0.098 kPa），q = 3.18，P < 0.01]。在RM后1.1 < b < 1.3时，PEEP为（16.8±1.1）cm H₂O，RV为（262±57）ml，高于RM后b = 1时（q = 2.54，P = 0.023）。在RM后0.6 < b < 0.8时，PEEP为（5.6±2.2）cm H₂O，RV低于RM后b = 1时（q = 2.85，P = 0.013）。RM后b = 1、0.6 < b < 0.8和1.1 < b < 1.3时动脉血氧分压（PaO₂）分别为（319±49）mmHg（1 mmHg = 0.133 kPa）、（246±57）mmHg和（314±27）mmHg，高于无RM时b = 1时的PaO₂[（153±64）mmHg，所有q = 2.81，所有P < 0.05]。0.6 < b < 0.8时的PaO₂低于RM后b = 1时（q = 2.81，P = 0.005），而1.1 < b < 1.3时的PaO₂与RM后b = 1时无显著差异。1.1 < b < 1.3时的气道峰压和平台压高于RM后b = 1时（q = 6.02，5.72，所有P < 0.05）。