Central hemodynamics during lung recruitment maneuvers at hypovolemia, normovolemia and hypervolemia.: A study by echocardiography and continuous pulmonary artery flow measurements in lung-injured pigs

Objective: The impact of lung-recruitment maneuvers on heart function at different volemic levels has not been studied in detail. We therefore investigated the effect on central hemodynamics of lung recruitment maneuvers at hypovolemia, normovolemia and hypervolemia in experimental lung injury. Design: Randomized, controlled, cross-over experimental study. Setting: Animal laboratory at a university hospital. Participants: Eleven anesthetized and lung-lavaged pigs. Intervention: The animals were randomized to 10-s lung recruitment maneuvers followed by 30-s maneuvers (40 cm H2O airway pressure) or vice versa, performed under hypovolemia, normovolemia and hypervolemia. Measurements and main results: Left-ventricular end-diastolic diameter and cardiac output were measured before, during, and 1 min and 5 min after the lung recruitment maneuver and left-ventricular eccentricity index was calculated for before and during the maneuver. Cardiac output and left-ventricular end-diastolic diameter ( within parentheses) decreased significantly during both the 10-s and 30-s lung recruitment maneuvers at hypovolemia, by a mean of 89% (35) and 92% (33), at normovolemia by 75% (33) and 86% (32), and at hypervolemia by 56% (32) and 64% (43), respectively. At hypovolemia, cardiac output was increased above baseline 1-5 min following the 30-s maneuver. Left-ventricular eccentricity index increased significantly during the maneuver, indicating right ventricular dysfunction. Conclusions: In this animal lung injury model, lung recruitment maneuvers significantly decreased left-ventricular end-diastolic volume and cardiac output at hypovolemia. Hypervolemia did partly counteract this compromise. In addition, a marked right-ventricular dysfunction during the maneuver was found.