J Thorac Cardiovasc Surg 1994;107:1160-1161
© 1994 Mosby, Inc.
Neutrophil elastase release and cardiopulmonary bypass
N. K. Gupta, MCh,
P. G. Martin, PhD,
C. M. Satur, FRCS,
D. Greenstein, MB, ChB,
D. R. Walker, FRCS
Department of Cardiothoracic Surgery
The Killingbeck Hospital
Leeds LS14 7UQ, United Kingdom
To the Editor:
We read with interest the article titled "Effect of Cardiopulmonary Bypass on Systemic Release of Neutrophil Elastase and Tumor Necrosis Factor" by Butler and associates 
1 In a similar but extended study 2 performed in this unit, 19 patients undergoing coronary artery bypass operations were followed up until the day of their discharge (mean 7 days). Baseline (preoperative) plasma neutrophil elastase levels measured by Butler and associates differed tenfold from our measurements, which were also confirmed by normal range data provided by Merck (PMN Elastase IMAC, Darmstadt, Germany), of 22 ± 20 ng/ml (mean plasma elastase concentration ± 2SD of 172 healthy male and female controls). Whether this difference is due to methods necessitates closer scrutiny. In our study, plasma neutrophil elastase levels were factorized for neutrophil count (10 3/µl) at each interval. Although the factorized values were significantly higher at the end of bypass, median value 17.3 ng/ml (preoperative value 8.1 ng/ml, p < 0.001), a further increase was observed at the 96-hour sampling point (25.4 ng/ml) not measured by Butler and associates. This increase also corresponds with the peak neutrophil count (243% of baseline). At the time of discharge (mean 7 days) plasma neutrophil elastase values remained elevated (17.1 ng/ml, p < 0.001). Because elastase is an important by-product of the contact activation of neutrophils and because neutrophil number is known to increase during bypass, 3 the use of factorized neutrophil elastase levels may be more reflective of changes in neutrophil activation during and after cardiopulmonary bypass. This may also explain the weak correlation between cardiopulmonary bypass time and neutrophil elastase levels reported by Butler and colleagues but not confirmed by count factorization of neutrophil elastase values in our study. Because neutrophil elastase is not exclusively released in the lungs at the time of ischemic reperfusion after bypass but possibly in other relatively ischemic organs and the extracorporeal circuit because of contact activation, it may be relevant to examine multiorgan dysfunction caused both during and after cardiopulmonary bypass. In an ongoing study (unpublished) involving 21 patients, in which the Apache III scoring system 4 was used to score patient morbidity, a significant correlation between scores and factorized neutrophil elastase values at 24 hours, 96 hours, and 7 days after cardiopulmonary bypass has been identified (rank Spearman correlation [rs] = 0.85, p < 0.001; rs = 0.65, p = 0.03; rs = 0.76, p = 0.01; respectively). Preliminary analysis of our data is indicative of a relationship between postoperative neutrophil activation (elastase levels) and quantity of homologous banked blood transfusion (rs = 0.58, p < 0.04), although a larger prospective study is indicated.
In conclusion, count factorization of neutrophil elastase values and extended postoperative follow-up of patients may assist delineation of the relationship between plasma neutrophil elastase and postcardiopulmonary bypass morbidity and as observed in our study reveal peak neutrophil activation and polymorphonuclear leukocytosis to occur later than that reported by Butler and colleagues.
References
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Butler J, Pillai R, Rocker GM, Westaby MS, Parker D, Shale DJ. Effect of cardiopulmonary bypass on systemic release of neutrophil elastase and tumor necrosis factor. J THORAC CARDIOVASC SURG 1993;105:25-30.[Abstract]
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Gupta NK, Martin P, Greenstein D, Gebitekin C, Walker DR. Deranged neutrophil function following cardiopulmonary bypass. Presented at the Third World Congress of the International Society of Cardiothoracic Surgeons, Salzburg, January 25-27, 1993. Cor Europeum [In press].
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Quiroga MM, Miyagishima R, Haendschen LC, Glovsky M, Martin BA, Hogg JC. The effect of body temperature on leukocyte kinetics during cardiopulmonary bypass. J THORAC CARDIOVASC SURG 1985;90:91-6.[Abstract]
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Knaus WA, Wagner DP, Draper EA, et al. The APACHE-III prognostic system: risk prediction of hospital mortality for critically ill hospitalized adults. Chest 1991;100:1619-36.[Abstract/Free Full Text]
