Normoxic cardiopulmonary bypass reduces oxidative myocardial damage and nitric oxide during cardiac operations in the adult.
OBJECTIVE
Hyperoxic cardiopulmonary bypass is widely used during cardiac operations in the adult. This management may cause oxygenation injury induced by oxygen-derived free radicals and nitric oxide. Oxidative damage may be significantly limited by maintaining a more physiologic oxygen tension strategy (normoxic cardiopulmonary bypass).


METHODS
During elective coronary artery bypass grafting, 40 consecutive patients underwent either hyperoxic (oxygen tension = 400 mm Hg) or normoxic (oxygen tension = 140 mm Hg) cardiopulmonary bypass. At the beginning and the end of bypass this study assessed polymorphonuclear leukocyte elastase, nitrate, creatine kinase, and lactic dehydrogenase, antioxidant levels, and malondialdehyde in coronary sinus blood. Cardiac index was measured before and after cardiopulmonary bypass.


RESULTS
There was no difference between groups with regard to age, sex, severity of disease, ejection fraction, number of grafts, duration of cardiopulmonary bypass, or ischemic time. Hyperoxic bypass resulted in higher levels of polymorphonuclear leukocyte elastase (377 +/- 34 vs 171 +/- 32 ng/ml, p = 0.0001), creatine kinase 672 +/- 130 vs 293 +/- 21 U/L, p = 0.002), lactic dehydrogenase (553 +/- 48 vs 301 +/- 12 U/L, p = 0.003), antioxidants (1.97 +/- 0.10 vs 1.41 +/- 0.11 mmol/L, p = 0.01), malondialdehyde (1.36 +/- 0.1 micromol/L,p = 0.005), and nitrate (19.3 +/- 2.9 vs 10.1 +/- 2.1 micromol/L, p = 0.002), as well as reduction in lung vital capacity (66% +/- 2% vs 81% +/- 1%,p = 0.01) and forced 1-second expiratory volume (63% +/- 10% vs 93% +/- 4%, p = 0.005) compared with normoxic management. Cardiac index after cardiopulmonary bypass at low filling pressure was similar between groups (3.1 +/- 0.2 vs 3.3 +/- 0.3 L/min per square meter). [Data are mean +/- standard error (analysis of variance), with p values compared with an oxygen tension of 400 mm Hg.]


CONCLUSIONS
Hyperoxic cardiopulmonary bypass during cardiac operations in adults results in oxidative myocardial damage related to oxygen-derived free radicals and nitric oxide. These adverse effects can be markedly limited by reduced oxygen tension management. The concept of normoxic cardiopulmonary bypass may be applied to surgical advantage during cardiac operations.
Ihnken
K
K
Department of Cardiothoracic and Vascular Surgery, Johann-Wolfgang-Goethe University, Frankfurt, Germany.
Winkler
A
A
Schlensak
C
C
Sarai
K
K
Neidhart
G
G
Unkelbach
U
U
Mülsch
A
A
Sewell
A
A
D000328:Adult; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000601:surgery; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000097:blood; D019272:Leukocyte Elastase / Q000097:blood; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D015428:Myocardial Reperfusion Injury / Q000097:blood / Q000503:physiopathology / Q000517:prevention & control*; D009504:Neutrophils / Q000201:enzymology; D009569:Nitric Oxide / Q000097:blood*; D018384:Oxidative Stress; D010102:Oxygen Inhalation Therapy; D011184:Postoperative Period; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D016277:Ventricular Function, Left
D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D008315:Malondialdehyde; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; D019272:Leukocyte Elastase