Post-operative circulating cytokine patterns--the influence of infection.

OBJECTIVE: To study post-operative plasma concentrations of tumor necrosis factor alpha (TNF), interleukin-1 beta (IL-1) and interleukin-6 (IL-6) in infected and non-infected patients.
DESIGN: Prospective controlled clinical study.
SETTING: The intensive care unit (ICU) of a university hospital. PATIENTS AND PARTICIPANTS: The study comprised 20 patients, 9 infected and 11 non-infected, consecutively admitted to the ICU after moderate or major surgery. Twelve healthy volunteers were used as controls. MEASUREMENTS AND
RESULTS: Leucocyte count, CRP and the plasma TNF, IL-1 and IL-6 concentrations were studied 24-48 h after the start of surgery. Axillary temperature, the duration of surgery, the number of packed red cells transfused, the APACHE II score and outcome were registered. Both infected and non-infected patients had higher plasma concentrations of IL-6 than the controls (p < 0.001 and p < 0.01 respectively). Patients with infection had a higher plasma IL-6 concentration than non-infected patients (p < 0.05). Similar analyses of plasma TNF concentrations revealed no differences between infected and non-infected patients. Plasma IL-1 was detected only occasionally. Non-survivors (n = 4) had higher plasma concentrations of TNF and IL-6 than survivors (p < 0.05 and p = 0.05 respectively). In non-infected patients a correlation between the number of units of packed red cells transfused and the plasma IL-6 concentration was observed (r = 0.73, p < 0.05).
CONCLUSION: No specific plasma cytokine pattern for infected patients subjected to surgery was observed. The effect of surgery and infection on the plasma IL-6 concentration seemed to be additive. Transfusion of packed red cells appeared to elevate the post-operative plasma IL-6 concentration.