Intraoperative thoracic epidural ropivacaine 0.5%, but not 0.2%, results in a greater inhaled anesthetic-sparing effect during major abdominal surgery

◊ SUMMARY:

The authors studied the intraoperative effects of two different concentrations of ropivacaine (0.5% vs 0.2%), administered via an epidural catheter, inserted at interspace T7-T8, in 45 patients undergoing major upper abdominal surgery with combined thoracic epidural analgesia and general anesthesia.

Three groups of patients were studied receiving either ropivacaine 0.5% + 0.5 µg/mL sufentanil (group A); ropivacaine 0.2% + 0.5 µg/mL sufentanil (group B); or saline (group C). After insertion of the epidural catheter a test dose of 4 mL of plain lidocaine 2% was injected to reveal subarachnoid misplacement. For intraoperative analgesia, an hourly dose of 10 mL of the study solution was administered epidurally. All patients were given similar general anesthesia (propofol-rocuronium-desflurane-O2/N2O). Intraoperative desflurane administration was adjusted to maintain anesthesia between 50 and 55 as assessed by the Bispectral Index monitoring and common clinical signs (PRST score), based on heart rate arterial blood pressure, diaphoresis, and lacrimation. Remifentanil was used as intraoperative rescue analgesia. For postoperative pain relief a continuous infusion of 10 mL/h of 0.2% ropivacaine + 0.5 µg/mL sufentanil was given, with the option of a patient-controlled bolus of 5 mL (lockout period of 20 min).

The first tested hypothesis that higher concentrations of epidurally administered ropivacaine would lead to a more pronounced reduction in desflurane requirements was clearly verified. Downward titration of desflurane was more often required in the 0.5% ropivacaine group compared to the 0.2% group, while no reduction was possible in group C. A second hypothesis of a more distinct impairment of hemodynamics was also tested. Hypotension occurred in all patients of groups A and B, although there were no differences among groups regarding requirement for crystalloids, colloids, and norepinephrine to maintain the mean arterial pressure within 20% of the baseline values.

Remifentanil administration was not necessary in any patient of group A whereas it was required in all patients of group C (no intraoperative local anesthetics) throughout the abdominal operation (Group C: 7.2, B: 1.6, A: 0 mg/h).

No patient showed intra- or postoperative complications (including no intraoperative awareness and recall) and all could be discharged home within 21 days of surgery.

◊ Reviewed by A. Van Zundert, MD, PhD, FRCA,
Catharina Hospital,
Professor of Anesthesiology
Brabant Medical School Eindhoven Netherlands
Eindhoven, Netherlands

The postoperative benefits of thoracic epidural analgesia compared to intravenous patient-controlled opioid analgesia are known. A combination of epidural local anesthetics and opioids results in superior postoperative pain relief, a reduction in hormonal and metabolic stress, and a fast restoration of the gastrointestinal function. Accordingly, it has become part of fast-track surgery, allowing a short recovery time with early mobilization.

However, intraoperative benefits of epidural use of local anesthetics and opioids such as lower desflurane requirements and less affected hemodynamics have never been clearly demonstrated. Panousis et al. have to be congratulated for this excellent study which clearly demonstrates that good intraoperative neuraxial analgesia can be achieved with a thoracic epidural technique, whereby the catheter should be used to prolong satisfactory analgesia beyond surgery.