SERUM CONCENTRATIONS OF INTERLEUKIN-6, TUMOR-NECROSIS-FACTOR-ALPHA, AND C-REACTIVE PROTEIN IN PATIENTS UNDERGOING MAJOR OPERATIONS

Objective: To investigate the kinetics of interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha) and C-reactive protein after a surg ical operation. Design: Prospective study. Setting: Teaching hospital, Sweden. Subjects: 28 patients undergoing cardiac operations, joint re placement, or gastric restrictive operations. Interventions: Samples o f serum were taken before operation; at 0, 6, and 12 hours; and then d aily for six days. Outcome measures: IL-6, TNF-alpha, and C-reactive p rotein concentrations at specified time points, and their correlation with complications and outcome. Results: The IL-6 concentration peaked soon after operation, and that of C-reactive protein 48-96 hours late r. Serum IL-6 concentrations were highest in the eight patients underg oing cardiac operations. In one patient an infective complication occu rred resulting in secondary peaks of IL-6 and C-reactive protein. Thre e patients who developed postoperative circulatory and respiratory ins tability had no additional changes in cytokine concentrations. The ove rall concentrations of IL-6 were raised above 100 pg/ml for a mean of 36 hours after operation and those of C-reactive protein were over 100 mg/l for a mean of 106 hours (p < 0.0001). Serum TNF-alpha concentrat ions were low in all patients. Conclusion: The maximum serum concentra tions of IL-6 and C-reactive protein after surgical operations were co mparable to those in patients with sepsis. If IL-6 and C-reactive prot ein analyses are used in the diagnosis of infective complications, eva luation of the results should be related to the length of time between the operation and sampling, and to the clinical findings. The shorter period during which IL-6 was raised compared with C-reactive protein indicates that IL-6 may be a more useful marker of postoperative infec tive complications.