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J Thorac Cardiovasc Surg 1997;114:305-306
© 1997 Mosby, Inc.

LETTERS TO THE EDITOR

Hyperoxic cardiopulmonary bypass causes reoxygenation injury and lipid peroxidation

Cardiothoracic Department
St. Mary's Hospital
Praed Street
London W2 1NY, United Kingdom

Reply to the Editor:

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 Fallot ¹ may not be reliably transferred to adult human beings. During CPB, lipid peroxidation may well vary in different settings. Morita, ² Ihnken, ³ 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 coworkers ⁴ 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. ⁵ 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

References

1. Del 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(Suppl):V174-9.
   
2. Morita 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;110:1235-44.
   
3. Ihnken 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;110:1255-64.
   
4. Davies 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;64:236-40.[Abstract/Free Full Text]
   
5. Ihnken 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 (abstract). Circulation 1995;92(Suppl):I763-4.
   

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Leonidas Hadjinikolaou Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hadjinikolaou, L. Search for Related Content PubMed Articles by Hadjinikolaou, L.