[Effect of lung stress index on titration of positive end-expiratory pressure at post-recruitment in three canine acute respiratory distress syndrome models].
OBJECTIVE
To investigate the relationship of lung stress index and positive end-expiratory pressure (PEEP) at post-recruitment in different canine acute respiratory distress syndrome (ARDS) models.


METHODS
The ARDS models were induced by intravenous oleic acid, saline lavage and hydrochloric acid aspiration in anesthetized dogs. During volume control ventilation with constant inspiratory flow, PEEP was set to obtain a b (stress index) value between 0.9 and 1.1 (b = 1) before and post recruitment maneuver (RM). PEEP was changed to obtain b < 1 (0.6 < b < 0.8) and b > 1 (1.1 < b < 1.3). Meanwhile, the recruited volume (RV) was measured and pulmonary mechanics and gas exchange were observed.


RESULTS
At b = 1 after RM, PEEP were (10.8 +/- 2.3), (12.8 +/- 1.8) and (9.2 +/- 1.8) cm H2O in the oleic acid, saline-lavaged and hydrochloric acid aspiration groups, respectively. PEEP in saline-lavaged group was higher than that in hydrochloric acid aspiration group (P < 0.05). The ratio of partial arterial oxygen tension and fraction of inspiratory oxygen (PaO(2)/FiO(2)) at b = 1 without RM was lower than those post-RM in all three groups (P < 0.05). In oleic acid group, PaO(2)/FiO(2) at b = 1 post-RM was (399 +/- 61) mm Hg, which was higher than that at b < 1 [(307 +/- 71) mm Hg], but there was no difference between those at b = 1 and b > 1. At b = 1 after RM, PaO(2)/FiO(2) in the saline-lavaged group was higher than that in acid aspiration group, but no difference between saline-lavaged group and oleic acid group was found. At b = 1 post-RM, RV were higher than that at b = 1 before RM in all three groups (P < 0.01), but there was no significant difference among three groups. At b = 1 post-RM in three groups, pulmonary compliance were higher than those at b > 1, but airway plateau pressure were lower than those at b > 1.


CONCLUSIONS
Lung stress index could be a good indicator for PEEP titration at post-RM.
Qiu
Hai-bo
HB
Department of Critical Care Medicine, Zhong-Da Hospital and School of Clinical Medicine, Southeast University, Nanjing 210009, China. haiboq2000@yahoo.com.cn
Chen
Yong-ming
YM
Yang
Yi
Y
Shen
Ju-fang
JF
Li
Jia-qiong
JQ
Li
Na
N
Wu
Bin
B
D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006851:Hydrochloric Acid / Q000494:pharmacology; D008168:Lung / Q000503:physiopathology*; D008170:Lung Compliance; D008297:Male; D019301:Oleic Acid / Q000494:pharmacology; D011175:Positive-Pressure Respiration; D012128:Respiratory Distress Syndrome / Q000139:chemically induced / Q000503:physiopathology / Q000628:therapy*; D012129:Respiratory Function Tests; D012965:Sodium Chloride / Q000494:pharmacology
D019301:Oleic Acid; D012965:Sodium Chloride; D006851:Hydrochloric Acid