Surgical trauma affects the proinflammatory status after cardiac surgery to a higher degree than cardiopulmonary bypass

Cytokines contribute to the development of the systemic inflammatory response syndrome or multiple-organ failure frequently observed after cardiopulmonary bypass-supported cardiac surgery. To quantify the contribution of bypass-induced versus trauma-induced inflammatory response after coronary artery bypass grafting, we examined plasma cytokine levels in 120 patients with coronary artery disease who were treated with or without cardiopulmonary bypass-assisted procedures.

Patients were treated in accordance with one of the following protocols: (1) elective percutaneous coronary intervention without cardiopulmonary bypass (n = 69), (2) cardiopulmonary bypass-supported percutaneous coronary intervention (cardiopulmonary bypass-percutaneous coronary intervention; n = 10), and (3) cardiopulmonary bypass-supported coronary artery bypass grafting (cardiopulmonary bypass-coronary artery bypass grafting; n = 41). Cytokine levels (picograms/milliliter) were measured by enzyme-linked immunosorbent assay from plasma samples obtained at various time points.

Interleukin-6 was measured in blood samples from all 3 patient populations. The maximum interleukin-6 level was 13.6 +/- 22.3 pg/mL in the percutaneous coronary intervention group, 170.4 +/- 165.4 pg/mL in the cardiopulmonary bypass-percutaneous coronary intervention group, and 640.3 +/- 285.7 pg/mL in the cardiopulmonary bypass-coronary artery bypass grafting group. Interleukin-6 levels were significantly different, and the 95% confidence intervals did not overlap. In the cardiopulmonary bypass-percutaneous coronary intervention group, bypass duration correlated well with interleukin-6 production ( r = 0.915; P < .001), whereas these parameters did not correlate in patients who underwent cardiopulmonary bypass-coronary artery bypass grafting ( r = 0.307; P = .054).

These findings support the suggestion that surgical trauma and cardiopulmonary bypass contribute to the inflammatory response after cardiac surgery, although trauma may contribute to a higher degree.