Effect of cardiopulmonary bypass on systemic release of neutrophil elastase and tumor necrosis factor.

Leukocyte counts, plasma neutrophil elastase, tumor necrosis factor-alpha and C-reactive protein were determined serially in 19 patients undergoing elective coronary artery surgery with cardiopulmonary bypass. Neutrophil counts (mean +/- standard deviation 3.85 +/- 1.20 x 10(9)/L preoperatively) peaked 4 hours postoperatively at 10.35 +/- 4.24 x 10(9)/L (p < 0.001) and remained significantly elevated 48 hours postoperatively at 7.80 +/- 2.70 x 10(9)/L, p < 0.05. Plasma neutrophil elastase level (187 +/- 74 ng/ml preoperatively) peaked at 698 +/- 323 ng/ml at the end of surgery (p < 0.001) and remained significantly elevated at 424 +/- 146 ng/ml 48 hours postoperatively (p < 0.01). Peak elastase levels correlated significantly with duration of bypass (r = 0.47, n = 19, p < 0.05). Monocyte counts (0.29 +/- 0.19 x 10(9)/L preoperatively) peaked 4 hours postoperatively (0.87 +/- 0.41 x 10(9)/L, p < 0.001) and fell to baseline levels by 48 hours postoperatively. Plasma tumor necrosis factor-alpha, detectable in 10 of the 19 patients preoperatively (median 0.39 U/ml, range up to 10.1 U/ml), did not change significantly during or after bypass. Plasma C-reactive protein level (median 1.67 [range 0.69 to 34.33] micrograms/ml preoperatively) rose significantly to 3.99 (range 1.95 to 12.55) micrograms/ml 4 hours postoperatively (p < 0.01) and rose 48 hours postoperatively at 303 (210 to 410) micrograms/ml, p < 0.001. Oxygenation, determined by the respiratory index, was impaired at the end of operation (2.07 +/- 0.82) and remained impaired 24 hours postoperatively (2.48 +/- 0.83). Impairment of oxygenation was temporally related to elevated elastase levels, but neither peak elastase levels nor the change in elastase levels with lung reperfusion correlated significantly with the area under the respiratory index curve up to 6 hours postoperatively. This study demonstrates neutrophil elastase release during cardiopulmonary bypass but fails to show a definite role for neutrophil activation or tumor necrosis factor-alpha in the etiology of pulmonary dysfunction after cardiopulmonary bypass.