Silent myocardial ischaemia in diabetic patients after general anaesthesia with 24 h intravenous opioids or with epidural analgesia

Objective
To evaluate the effect of general anaesthesia with either continuous i.v. opioids (G/O) or thoracic epidural analgesia (G/EP) on postoperative transient myocardial ischaemia (TMI) in type 2 diabetic patients undergoing open cholecystectomy.
Methodology
This randomised controlled study was conducted on 50 patients with D.M. Patients were divided into G/O group or G/EP group. All patients had negative stress exercise test and at least two cardiac risks preoperatively. Epidural analgesia was established by 15 ml of ropivacaine 0.2% with fentanyl 2 μg/ml followed by 5–8 ml/h of ropivacaine 0.1% with fentanyl 1 μg for 24 h postoperatively. Both studied groups received same general anaesthesia. Continuous i.v. fentanyl 100 μg/h was given intraoperatively in group G/O followed by i.v. morphine PCA. Primary outcome measured postoperative TMI using 24 h continuous ST segment analysis, endothelin-1(ET-1), troponin T, creatine kinase MB (CK-MB), and CKMB/CK preoperatively, 8 h and 24 h postoperatively. Second outcome measured dynamic stress (perioperative heart rate, blood pressure and postoperative pain).
Results
Endothelin-1 was above cutoff level preoperatively and rose up dramatically postoperatively in both studied groups. G/EP attenuated ET-1 elevation than G/O. Troponin T and CK-MB did not rise postoperatively in both studied groups. Postoperative CK-MB/ CK ratio was higher than 10% in 12 and eight patients in group G/O and G/EP, respectively. Twelve cardiac ischaemic events were noticed in four patients in group G/O and four events in two patients in group G/EP without significant difference in total duration of ischaemia between groups. G/EP lowered HR more significantly intraoperatively and gave better pain control for 4 h postoperatively. In conclusion, D.M was associated with high ET-1 level. Upper abdominal surgery increased ET-1 release. G/EP attenuated ET-1 release more than G/O and produced more stable haemodynamic parameters and less postoperative pain. No superior cardioprotective effect was noticed in G/EP over G/O.