[Effects of recruitment maneuvers in prone position for pulmonary or extra-pulmonary acute respiratory distress syndrome on hemodynamics in dog].

OBJECTIVE: To evaluate the effect of recruitment maneuvers in prone positioning on hemodynamic in dogs with acute respiratory distress syndrome (ARDS) of pulmonary or extra pulmonary origin.

METHODS: Forty-eight mongrel dogs were randomly divided into 8 groups with six dogs in each group. Hydrochloric acid was instilled into trachea to reproduce pulmonary ARDS (ARDSp) and oleic acid was intravenously injected to produce extra-pulmonary ARDS (ARDSe). ARDSp and ARDSe dogs were divided into conventional mechanical ventilation group (group A), prone-position ventilation group (group B), sustained inflation (SI) group (group C) and prone-position ventilation + SI group (group D) respectively. Hemodynamic parameters were monitored before injury and 0, 2 and 5 hours after ARDS was reproduced.

RESULTS: (1) In group A and group C, central venous pressure (CVP) increased significantly at 5 hours after ARDSp. Five hours after the establishment of ARDSp, pulmonary arterial wedge pressure (PAWP) increased in group C and group D. Mean pulmonary arterial pressure (MPAP) increased remarkably in group A, group C and group D at 2 hours and 5 hours after onset of ARDSp. In group C, intrathoracic blood volume index (ITBI) decreased at 5 hours after the onset of ARDSp. In all the four groups, extravascular lung water index (EVLWI) increased sharply at 0, 2 and 5 hours after onset of ARDSp. In group B and group C, cardiac index (CI) decreased to a greater extent at 2 and 5 hours after onset of ARDSp. CI decreased at 2 hours after onset of ARDSp in group D with statistically significant difference at different time points (all P<0.05). (2) In all four groups, EVLWI increased sharply at 0, 2 and 5 hours after onset of ARDSe. In ARDSe model, there was no significant difference in other hemodynamic parameters between groups (all P>0.05).

CONCLUSION: There are less influence on hemodynamics when SI is performed in prone position, and it is even more significantly so in ARDS dogs.