Recruitment maneuver leads to increased expression of pro-inflammatory cytokines in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a disease with high morbidity and mortality rates. The recruitment maneuver (RM) is one of the interventions used for ARDS patients suffering from severe hypoxemia. RM works by opening the atelectatic lungs using high transpulmonary pressure. RM has therefore been widely used for many years in patients with ARDS. However, because of the high transpulmonary pressure used in this intervention, there are concerns about both biotrauma and hemodynamic instability. To assess the effects of RM in ARDS, we conducted a study using three groups of pigs (n = 6 in each group): group I (control), group II (ARDS), and group III (ARDS with RM). After measuring the baseline values, ARDS was induced by deactivating the surfactant with 5% Tweens lavage. For pigs of group III, the RM protocol used was positive end-expiratory pressure (PEEP) of 25 cmH(2)O and peak pressure of 45 cmH(2)O. Gas exchange, hemodynamics, the expression of cytokines in serum, bronchoalveolar lavage fluid (BALF), and exhaled breath condensates (EBCs) were measured. The baseline measurements taken were similar across the three groups, and no significant difference was noted. After the induction of ARDS, PaO2 substantially decreased, while PaCO2, alveolar-arterial O-2 gradient, pulmonary arterial pressure, lung water, level of cytokines in serum, EBCs, and BALF all increased. After RM, gas exchange and lung water level improved, but the level of cytokines in EBCs and BALF increased. Although RM led to an improvement in gas exchange, it may cause release of inflammatory cytokines in the EBCs and BALF.