|Methods||Randomized controlled trial|
|Participants||60 patients undergoing elective cardiac surgery|
Exclusion criteria included left ventricular ejection fraction of less than 25%, hypothermic circulatory arrest, recent myocardial infarction, preoperative inotropic or intra-aortic balloon pump metabolic, or neurologic diseases. All patients were receiving chronic B-adrenoceptor blocking drugs
|Interventions||Alfentanil or low dose remifentanil or high dose remifentanil or epidural (15 patients in the epidural and 45 patients in the control group)|
A test dose of 2 mL of lidocaine 2% was given to test for the correct position of the catheter. A loading dose of 10 mL of bupivacaine 0.25% with 2.5 mg of morphine was infused over 1 hour.
In the present study, 4 groups of patients were compared as follows: group 1 (AG): a loading dose of alfentanil, 50 ug/kg, was infused over 4 minutes, and, thereafter, alfentanil was infused at a maintenance rate of 1 ug/kg/min throughout surgery; group 2 (HDRG): a loading dose of remifentanil, 2.5 ug/kg, was infused over 4 minutes, and, thereafter, remifentanil was infused at a maintenance rate of 0.5 ug/kg/min throughout surgery; group 3 (LDRG): a loading dose of remifentanil, 2.5 ug/kg, was infused over 4 minutes, and, thereafter, remifentanil was infused at a maintenance rate of 0.25 ug/kg/min; and group 4 (TEG): a loading dose of remifentanil, 2.5 ug/kg, was infused over 4 minutes, and, thereafter, remifentanil was infused at a maintenance rate of 0.125 ug/kg/min and via thoracic epidural infusion bupivacaine 0.375% plus morphine 0.2 mg/mL were administered at a rate of 1.5 mL/hr throughout surgery. The initial infusion setting for propofol on the Diprifusor was a plasma concentration of 2 ug/mL to be reached in 4 minutes.
At arrival in the ICU, a sedative-analgesic infusion of propofol, 0.5 mg/kg/hr, together with alfentanil, 0.1 ug/kg/min, in group 1 and remifentanil, 0.025 g/kg/ min, in groups 2, 3, and 4, were started for 4 hours. If necessary, propofol was increased to achieve the desired level of sedation (Ramsay sedation score 3, 4, or 5). Additionally, acetaminophen, 1 g, 4 times daily, was started as a basic analgesic. In the TEG group, the catheter was left in position 48 hours postoperatively and bupivacaine 0.125% and morphine, 0.2 mg/mL, were infused at a rate of 1.5 mL/hr. Fifteen minutes before cessation of the sedative analgesic infusion, pirinitramide, a synthetic morphine derivative (analgesic potency in comparison with morphine  is 0.7) 0.15 mg/kg, intravenously, was administered in the remifentanil groups 2 and 3, and placebo was administered to the AG in a blinded fashion.
|Outcomes||Infectious parameters (CRP, IL-6)|
|Risk of bias|
|Bias||Authors' judgement||Support for judgement|
|Random sequence generation (selection bias)||Low risk||"60 patients scheduled to undergo coronary artery bypass surgery were randomized"|
|Allocation concealment (selection bias)||Unclear risk||Not stated|
|Blinding (performance bias and detection bias) |
|Low risk||The study was blinded for the opioid infusion, except in the thoracic epidural group|
|Incomplete outcome data (attrition bias) |
|Unclear risk||Not stated|
|Selective reporting (reporting bias)||Low risk||Appears to be free of other sources of bias. Sample size calculation not stated|