Comparison of Three Different Epidural Solutions in Cardiac Surgery for Stress Protection

Background: Different solutions are possible for thoracic epidural analgesia in cardiac surgery. So far, local anesthetics alone or in combination with either clonidine or opioids have been used. Aims: To determine the stress protection provided by different epidural solutions throughout cardiac surgery. Study Design: A randomized, prospective, double blind study in patients undergoing off-pump coronary artery bypass grafting (OPCAB), randomized in three different groups. Thoracic epidural analgesia was installed more than 1 h before application of heparin at levels of T2 to T4; analgesia was provided by 8 ml of bupivacaine 0.25% 15 min prior to surgery and extubation, and 10 ml/h during and up to 72 h after surgery using one of the following regimens: bupivacaine 0.125% solely, bupivacaine 0.125% with fentanyl 3 g/mL or bupivacaine 0.125% with clonidine 0.6 g/mL. Patients were blockrandomized for one of the three treatments. Cortisol and glucose values were determined before surgery, at extubation and 1h and 3h after surgery. Pain scores were assessed up to 48 h after surgery. Hemodynamic stability was also recorded in form of heart rate, systolic and diastolic blood pressure. Multi-comparison ANOVA and Chi-square test were used to compare the data, presented as mean (SD) or median (25 th and 75 th percentile), P < 0.05. Study Setting: A cardiac surgery unit at a tertiary university hospital. Participants: Forty-two patients undergoing OPCAB were enrolled. Main Results: All patient data as well hemodynamic stability were not different between the three groups. All patients were successfully extubated in theatre immediately after surgery. Pain control was good and not significantly different between the groups. Mean glucose concentrations ± SD before surgery and (significantly higher) 3h after surgery were 5.4 ± 1.0 mmol l -1 and 8.4 ± 1.6 mmol l -1 for bupivacaine alone, 5.2 ± 0.5 mmol l -1 and 8.5 ± 2.2 mmol l -1 for bupivacaine plus fentanyl and 5.5 ± 1.6 mmol l -1 and 9.5 ± 2.1mmol l -1 for bupivacaine and clonidine, respectively. The mean cortisol values ± SD in the pre-operative period and 3h after surgery were 413 ± 162 nmol l -1 and 562 ± 173 nmol l -1 for bupivacaine alone, 393 ± 107 nmol l -1 and 581 ± 265 nmol l -1 for bupivacaine and fentanyl and 409 ± 159 nmol l -1 and 570 ± 160 nmol l -1 for bupivacaine and clonidine, respectively. There were no significant differences between the groups. Conclusions: We conclude that short-term stress protection with TEA is equally effective with solely bupivacaine, bupivacaine with fentanyl or clonidine.