Acute hemodynamic changes during lung recruitment in lavage and endotoxin-induced ALI

Objective: To assess acute cardiorespiratory effects of recruitment manoeuvres in experimental acute lung injury. Design: Experimental study in animal models of acute lung injury. Setting: Experimental laboratory at a University Medical Centre. Animals: Ten pigs with bronchoalveolar lavage and eight pigs with endotoxin-induced ALI. Interventions: Two kinds of recruitment manoeuvres during 1 min; a) vital capacity manoeuvres (ViCM) consisting in a sustained inflation at 30 cmH(2)O and 40 cmH(2)O; b) manoeuvres obtained during ongoing pressure-controlled ventilation (PCRM) with peak airway pressure 30 cmH(2)O, positive end-expiratory pressure ( PEEP) 15 and peak airway pressure 40, PEEP 20. Recruitment manoeuvres were repeated after volume expansion ( dextran 8 ml/kg). Oxygenation, mean arterial, and pulmonary artery pressures, aortic, mesenteric, and renal blood flow were monitored. Measurements and results: Lower pressure recruitment manoeuvres (ViCM30 and PCRM30/ 15) did not significantly improve oxygenation. With ViCM and PCRM at peak airway pressure 40 cmH(2)O, PaO2 increased to similar levels in both lavage and endotoxin groups. Aortic blood flow was reduced from baseline during PCRM40/20 and ViCM40 by 57 +/- 3% and 61 +/- 6% in the lavage group and by 57 +/- 8% and 82 +/- 7% ( P< 0.05 vs PCRM40/20) in endotoxin group. The decrease in blood pressure was less pronounced. Prior volume expansion attenuated circulatory impairment. After cessation of recruitment hemodynamic parameters were restored within 3 min. Conclusion: Effective recruitment resulted in systemic hypotension, pulmonary hypertension, and decrease in aortic blood flow especially in endotoxinemic animals. Circulatory depression may be attenuated using recruitment manoeuvres during ongoing pressure-controlled ventilation and by prior volume expansion.