The Protective Effects Of Cimetidine On The Immune Function Of Patients After Cardiopulmonary Bypass

Objective: Patient undergoing open-heart surgery with cardiopulmonary bypass support is apt to develop infectious complications. This might aggravate the patient's condition into multiple system organ failure (MOSF), which is one of the main etiologies of postoperative mortality in the open-heart surgery. It may be caused by the dysfunction of immune system after cardiopulmonary bypass. Cimetidine is one of the H₂ receptor blockers, which could specifically block the effects of H₂ receptor. There have been few foreign reports of Cimetidine's effects on cellular immune function, and no related domestic reports. Cemitidine's effects on cellular immune, fluid immune and erythrocytic immune in 30 cases of open-heart surgery under cardiopulmonary bypass and corresponding controls are investigated. Our aim is to study an effective means to protect immune function in open-heart patients, so that there will be less infectious complications and more successful cases. This is very important in both theoretical and practical aspects.Methods: Thirty cases of patients with rheumatic valve disease waiting for valvular replacement operations were enrolled randomly in our research group, these patients had no rheumatic attacks, no immune diseases, no infection before operation, and had not taken immunosuppressors for at least 6 months. All patientswere randomly enrolled in two groups. Operations of both groups were carried out with the support of German-made Stockert â…¢ cardiopulmonary bypass machine and Baxter membranous oxygenator. The perfusion flow was 60-80 milliliter per kilogram per minute with medium hypothermia. The myocardium was perfused intermittently with hyperkalemia blood cardioplegia during the aortic clamping. Four hundred milligrams of Cimetidine was infused after anesthesia during of 20 minutes at least. Cimetidine was infused at a dosage of 400 milligram per 12 hours on 0-5th days postoperation, each infusion was fulfilled during at least 60 minutes. The control group was processed routinely. There were no signicant differences on postoperative medication, management and nutrition support between two groups. Peripheral vein samples were collected in all patients on the day before operation, and on 1, 3,5,7,14th days postoperation. All the samples were anticoagulated with heparin and sent to central lab and immunology lab for further analysis. All the data were analyzed by the method of t-test and analysis of variation. All the data were shown as X±S, a=0.05, P<0.05 means that there was significant difference, and P<0.01 more significant.Results: (1) CD₃,CD₄ and CD₄/CD₈in both groups decreased significantly after operation,( P<0.01). CD₄, CD₄/CD₈ in Cimetidine group on 1^st and 3^rd days after operation were significantly higher than those in the control group.(P<0.05). CD₃,CD₄ and CD₄/CD₈ in Cimetidine group on 5^th, 7^th and 14^th days after operation were significantly higher than those in the control group(P<0.01). CD₃,CD₄ and CD₄/CD₈ in Cimetidine group returned to preoperative value 7 days after operation (P>0.05), the control group 14 days. (2) There was no significant difference in the NK cell activity (percentage) between two groups before operation. The activity dropped in both groups 1 day after operation, however the control group dropped more significantly vs. Cimetidine group (P<0.01). In Cimetidine group, the activity attained the lowest level on the 1^st day after operation, began to increase on the 3^rd day after operation, and return to normal level on the 7^th day after operation. In control group, 3^rd, 7^th and 14^th respectively. (3) IL-2 in two groups decreased significantly, but IL-2 in the Cimetidine group was higher than that of the control group on the 1^st, 3^rd and7l day after operation(P<0.01), it returned to normal value on 7th days after operation, and the control group 14th day. (4) In both groups, RBC-C3band RBC-ICR dropped rapidly after operation, the values on 1st, 3rd and 5th day after operation were significantly lower than that of preoperation (P<0.01). RBC-C3bRR in Cimetidine group on 5th, 7th and 14th day after operation was significantly higher than those in the control group(P<0.01), and returned to preoperative value on 7l day after operation (P>0.05), and higher than that of preoperation(P<0.05). RBC-C3bRR in control group returned to preoperative level on 14th day after operation(P>0.05). RBC-ICR in Cimetidine group on 5th, 7th and 14th day after operation was significantly higher than those in the control group(P<0.05). RBC-ICR in both Cimetidine and control groups returned to preoperative level on 14th day after operation (P>0.05).Conclusion: (1) Cimetidine has significant protective effect on the immune function in patients undergoing open-heart operation with cardiopulmonary bypass, intravenous infusion of Cimetidine is an effective means of protecting immune function in these patients, it can reduce the incidence of infectious complication, increase the possibility of success. This is very important in both theoretical and practical aspects. (2) This method is convenient, cheap, effective and safe.