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Abstract

We studied lipid peroxidation in adult patients undergoing cardiopulmonary bypass (CPB) for routine coronary artery bypass grafting (CABG). Assumptions about lipid peroxidation based on observations in immature piglets and cyanotic children with tetralogy of Fallot1Del Nido PJ Mickle DAG Wilson GJ Benson LN Coles JG Trusler GA et al.Evidence of myocardial free radical injury during elective repair of tetralogy of Fallot.Circulation. 1987; 76: V174-V179PubMed Google Scholar may not be reliably transferred to adult human beings. During CPB, lipid peroxidation may well vary in different settings. Morita,2Morita K Ihnken K Buckberg GD Sherman MP Young HH. Studies of hypoxemic/reoxygenation injury: without aortic clamping. IX. Importance of avoiding perioperative hyperoxemia in the setting of previous cyanosis.J Thorac Cardiovasc Surg. 1995; 110: 1235-1244Abstract Full Text Full Text PDF PubMed Scopus (33) Google Scholar Ihnken,3Ihnken K Morita K Buckberg GD. Studies of hypoxemic/reoxygenation injury: with aortic clamping. XI. Cardiac advantages of normoxemic versus hyperoxemic management during cardiopulmonary bypass.J Thorac Cardiovasc Surg. 1995; 110: 1255-1264Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar and their associates measured conjugated dienes and malondialdehyde as markers of lipid peroxidation in the myocardium of immature piglets and found a significant increase 5 minutes after the start of CPB. However, Davies and coworkers4Davies SW Underwood SM Wickens DG Feneck RO Dormandy TL Walesby RK. Systemic pattern of free radical generation during coronary bypass surgery.Br Heart J. 1990; 64: 236-240Crossref PubMed Scopus (64) Google Scholar measured lipid peroxidation in the coronary sinus in adult patients undergoing routine CABG and found no significant changes during CPB. The only related study seems to be an abstract reporting the results of a comparison between hyperoxic (Po2 400 mm Hg) and normoxic (Po2 150 mm Hg) CPB in 20 adult patients (63 ± 8 years) undergoing CABG.5Ihnken K Winkler A Beyersdorf F Neidhart G Winkelmann B Unkelbach U et al.Reduction of oxidative damage and nitric oxide on cardiopulmonary bypass by controlling Po2 during open heart surgery.Circulation. 1995; 92 (abstract): I763-I764Google Scholar Unfortunately, several questions arise from this report. Apart from being a very small study, the number of patients in each of the two groups was not stated. Crossclamp times and CPB times between the two groups were not compared, although their significance in lipid peroxidation is beyond question. Longer ischemic damage in the normoxic group might well have resulted in higher creatine kinase and malondialdehyde levels. Therefore our comment that “the contribution of hyperoxia to free radical generation and consequent lipid peroxidation in adult cardiac operations has to date not been addressed” should not be dismissed lightly. 12/8/82358