Lung recruitment maneuver effects on respiratory mechanics and extravascular lung water index in patients with acute respiratory distress syndrome

BACKGROUND:

Animal experiments showed that recruitment maneuver (RM) and protective ventilation strategy of the lung could improve oxygenation and reduce extravascular lung water. This study was to investigate the effects of RM on respiratory mechanics and extravascular lung water index (EVLWI) in patients with acute respiratory distress syndrome (ARDS).

METHODS:

Thirty patients with ARDS were randomized into a RM group and a non-RM group. In the RM group, after basic mechanical ventilation stabilized for 30 minutes, RM was performed and repeated once every 12 hours for 3 days. In the non-RM group, lung protective strategy was conducted without RM. Oxygenation index (PaO₂/FiO₂), peak inspiratory pressure (PIP), Plateau pressure (Pplat), static pulmonary compliance (Cst) and EVLWI of patients before treatment and at 12, 24, 48, 72 hours after the treatment were measured and compared between the groups. Hemodynamic changes were observed before and after RM. One-way ANOVA, Student''s t test and Fisher''s exact test were used to process the data.

RESULTS:

The levels of PaO₂/FiO₂ and Cst increased after treatment in the two groups, but they were higher in the RM group than in the non-RM group (P<0.05). The PIP and Pplat decreased after treatment in the two groups, but they were lower in the RM group than in the non-RM group (P<0.05). The EVLWI in the two groups showed downward trend after treatment (P<0.05), and the differences were signifcant at all time points (P<0.01); the EVLWI in the RM group was lower than that in the non-RM group at 12, 24, 48 and 72 hours (P<0.05 or P<0.01). Compared with pre-RM, hemodynamics changes during RM were significantly different (P<0.01); compared with pre-RM, the changes were not significantly different at 120 seconds after the end of RM (P>0.05).

CONCLUSIONS:

RM could reduce EVLWI, increase oxygenation and lung compliance. The effect of RM on hemodynamics was transient.KEY WORDS: Lung recruitment maneuver, Acute respiratory distress syndrome, Respiratory mechanics, Extravascular lung water index, Hemodynamics, Lung protective ventilation, Oxygenation index