Renal dysfunction following cardiopulmonary bypass (CPB) causes significant morbidity and mortality. There has been much research into possible methods of reducing renal damage, but much promising laboratory work has failed to live up to expectations in the clinical arena, such that there is no widely accepted renal protection strategy for cardiac surgical patients. Part of the difficulty is that there is no standardized definition of renal dysfunction, and there are a limited number of good quality randomised controlled clinical trials.

We compared Aminocaproic acid with tranexamic acid, prospectively in 120 patients undergoing coronary artery bypass surgery on cardiopulmonary bypass. Patients were assigned to one of the 3 groups. Group A (n=40) did not receive any drug and acted as the control group. Group B (n=4) received aminocaproic acid 100 mg/kg each at anaesthetic induction, on bypass and after protamine reversal of heparin. group C (n=40) received tranexamic acid 10 mg/kg each at anaesthetic induction, on bypass and after protamine reversal of heparin. Postoperative blood loss at 24 hours, blood and blood product usage, and re-exploration rates were recorded, and tests for coagulation were performed at 6 hours postoperatively. It was found that blood loss in group A at 24 hours (780+/-120 mL) was significantly greater than Group B (360+/-90 mL) and Group C (215+/-70 mL). Plasma and platelet concentrate use in Group A (215+/-30 mL and 150+/-30 mL) was greater than Group B (190+/-20 mL and 75+/-30 mL) and Group C (185+/-20 mL and 80+/-30 mL). Re- explorations in Group A, 8/40 (20%) were greater than Group B, 2/40 (5%) and Group C, 2/40 (5%). Coagulation tests revealed better preservation of fibrinogen and lower levels of fibrin degradation products, in group B and C. These two groups were however statistically indistinguishable in respect to all the parameters studied, when compared with each other. It was concluded that both the antifibrinolytic agents in the doses studied were equally effective in reducing postoperative blood loss, blood and blood products usage and re-exploration rates. Coagulation parameters were better preserved as compared to the control group.

The use of nonpulsatile flow during extracorporeal circulation remains popular despite theoretical advantages of pulsatile cardiopulmonary bypass (CPB). Pulsatile CPB is considered to be more physiological than nonpulsatile flow as the pulsatile energy ensures the patency of the vascular bed and mechanical motion of tissue fluid around the cell membrane, improves microcirculation and enhances diffusion. The purpose of this study was to compare the effect of pulsatile and nonpulsatile flow on the coagulation profile, liver and kidney function and also on the haemodynamics in patients undergoing coronary artery bypass grafting on CPB. One hundred patients between 35 and 65 years of age with normal left ventricular function were randomly divided into two equal groups: Pulsatile (P) and nonpulsatile (NP). Haematological parameters, clotting profile, renal parameters, hepatic function tests and haemodynamic variables were measured preoperatively and postoperatively at specific intervals. Surgical, anaesthetic and CPB regimen was standard in all cases. There was a decrease in platelet count during and after CPB in both groups. Coagulation profile and renal function parameters remained similar in both groups except that creatinine clearance was better in group P on the first postoperative day. Urine output was also better in group P. There was no change in liver function tests in both groups. The haemodynamic variables were comparable in both groups. The systemic vascular resistance was higher in group NP postoperatively and oxygen consumption was higher in group P post CPB. In conclusion we did not find any significant difference between pulsatile and nonpulsatile flow during CPB except the creatinine clearance and urine output were better in pulsatile group.

It is postulated that patients with ischaemic heart disease (IHD) and coronary steal prone anatomy (CSPA) may develop myocardial ischaemia under isoflurane anaesthesia. This study was conducted in 50 patients undergoing coronary artery bypass grafting. Among these 10 patients (20%) had CSPA, as evidenced by coronary angiography. Anaesthesia was induced with fentanyl, midazolam and thiopentone and maintained with isoflurane in oxygen after endotracheal intubation. Patients were continuously monitored with automated ST segment analysis of electrocardiogram (ECG) and transoesophageal echocardiography (TEE). The end-tidal concentration of isoflurane was maintained at 1.2%, which is equal to one minimum alveolar concentration. Haemodynamic parameters were maintained within 20% of baseline values with either the use of phenylephrine or increasing the depth of anaesthesia by using midazolam and fentanyl. ST changes were measured after 80 ms of J-point in ECG and TEE monitored for occurrence of new regional wall motion abnormalities during the study period. ST changes more than +/-1.0 mm were considered as an indication of myocardial ischaemia. Out of 10 patients having CSPA, 50% developed significant ECG changes during isoflurane anaesthesia at an endtidal concentration of 1.2%. In patients not having CSPA new ischaemia was not observed. Our study indicates necessity of close monitoring of patients with IHD and CSPA during isoflurane anaesthesia to identify new ischaemia and institute appropriate measures.