Recovery from Lymphocytopenia Following Extracorporeal Circulation: Simple Indicator to Assess Surgical Stress

This study investigated whether the lymphocyte count is a useful indicator to assess surgical damage following extracorporeal bypass. In Study 1, to investigate the correlation between extracorporeal circulating time (ECCT) and lymphocyte counts, 40 elective CABG patients were studied retrospectively. The lymphocyte recovery ratio (LRR), which represented the actual lymphocyte count divided by the preoperative lymphocyte count, was determined preoperatively, and on postoperative day (POD) 1, POD 3, and POD 5. In Study 2, the correlation between the interleukin-8 (IL-8) level and LRR was examined prospectively in elective CABG patients (n = 20). We measured the LRR and serum IL-8 levels preoperatively and during extracorporeal circulation (ECC) at 5 min, at the end of ECC, and 1, 3, and 12 h following ECC termination. Study 1 showed that the LRR decreased until POD 1 and gradually increased thereafter. The LRR had a negative correlation with the ECCT. In Study 2, the IL-8 level demonstrated a time course opposite to that of the LRR; it increased until 3 h after ECC termination and declined thereafter. There was a significant negative correlation between the LRR on POD 3 and the IL-8 level at 3 h after ECC termination. In summary, long-term ECC induced significant and prolonged lymphocytopenia. The LRR had a negative correlation with IL-8. These results indicated that the LRR may represent the degree of surgical stress following ECC; therefore, the counting of lymphocytes can be a quite useful bedside monitor to assess surgical damage and prognosis.