Pulmonary Protection in Cardiac Surgery

Abstract

Background: Pulmonary dysfunction is a common complication of cardiac surgery. Pulmonary protection strategies have evolved over the years; however, their efficacy remains controversial. Objective: To compare interventions aiming at reducing pulmonary dysfunction in patients undergoing coronary artery bypass grafting. The (BiPAP) trial [ISRCTN 85570732] investigated the efficacy of NIV with BiPAP in addition to usual care, versus usual care alone. The ventilate trial [ISRCTN 34428459] investigated LFV versus usual care during cardiopulmonary bypass. Outcome measures: In the BiPAP trial, the primary outcome was time until fit for discharge. In the ventilate trial, the primary outcome was inflammation measured by NF-B p65 activation in lung biopsies pre- and post- CPB. In a sub-study, pulmonary arteries were isolated from lung biopsies, to characterise changes in structure and function related to the CPB. Results: The median duration of the hospital stay until fit-for-discharge was 5 days for the BiPAP group (IQR, 4-6) and 6 days for the usual care group with a reduced incidence of adverse events. In the ventilate trial LFV (adjusted for pre-CPB level) compared to the standard care group had no effect on NF-B p65 activation in lung biopsies. In a sub-study, the pattern of anatomical and physiological changes in pulmonary artery obtained from lung biopsy pre- and post-CPB was described. Conclusions: The BiPAP trial, improved recovery time. The ventilate trial did not significantly improve clinical or inflammatory markers. For the first time in human we describe the structural and functional changes in pulmonary arteries from lung biopsy associated with CPB. A better understanding of available modalities of lung protection and/or combinations could result in the development of customised strategies for the different cohorts of patients with the potential to maximise patient and institutional benefits.