Relationship between respiratory distress and cytokine response after cardiopulmonary bypass

The influence of cytokines on the inflammatory response in surgery has recently been the subject of investigations. We measured tumor necrotic factor-alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), interleukin 8 (IL-8), and granulocyte elastase (GEL) in 26 patients undergoing elective cardiac operations using cardiopulmonary bypass (CPB), preoperatively, immediately after CPB, and on postoperative days (PODs) 1, 3, and 6. To evaluate the effect of these cytokines on pulmonary function, the patients were divided according to whether the oxygenation index (OI) on POD 1 was > 250 or < 250, into groups A and B, respectively. TNF-alpha and IL-1 beta were undetectable and there were no significant differences in the preoperative IL-6, IL-8, and GEL levels. However, immediately following CPB, the mean IL-6, IL-8 and GEL levels in both groups were significantly higher than the preoperative levels (P < 0.01). Moreover, all these levels were significantly higher in group B than in group A, at 162 +/- 150 pg/ml vs 64 +/- 53 pg/ml (P < 0.05) for IL-6; 53 +/- pg/ml vs 22 +/- 20 pg/ml (P < 0.01) for IL-8; and 2477 +/- 1642 mg/l vs 1397 +/- 774 mg/l (P < 0.01) for GEL. The IL-6 levels returned to the preoperative values in both groups on POD 1: however, the GEL levels remained significantly higher in group B than in group A postoperatively, at 616 +/- 326 mg/l vs 378 +/- 70 mg/l on POD 1, and at 292 +/- 70 mg/l vs 218 +/- 62 mg/l on POD 3 (P < 0.05). Thus high levels of cytokines such as IL-6, IL-8, and GEL may be detrimental to respiratory function.