High-dose remifentanil suppresses stress response associated with pneumoperitoneum during laparoscopic colectomy

Although laparoscopic surgery is minimally invasive, it produces stress responses to an extent similar to that of conventional laparotomy. Both epidural anesthesia and remifentanil intravenously (i.v.), combined with general anesthesia, provide stable hemodynamics during laparoscopic surgery. However, it has not been elucidated whether epidural anesthesia and remifentanil are associated with suppression of autonomic and neuroendocrine stress responses. This study aimed to clarify whether thoracic epidural anesthesia (TEA) or remifentanil suppresses stress responses during laparoscopic surgery. We assigned 60 patients undergoing laparoscopic colectomy to three groups anesthetized with 40 % oxygen-air-sevoflurane plus either TEA (TEA group), continuous infusion of remifentanil 0.25 mu g/kg/min [low-dose (LD) group], or 1.0 mu g/kg/min [high-dose (HD) group] (n = 20 each group). Plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, antidiuretic hormone (ADH), and catecholamines were measured immediately before anesthesia induction, and 30 and 90 min after the start of pneumoperitoneum. All groups showed no significant changes in hemodynamics during the course of anesthesia. Compared with TEA, both high-dose and low-dose remifentanil significantly suppressed increases in ACTH, ADH, and cortisol during pneumoperitoneum. Plasma adrenaline showed no significant changes during pneumoperitoneum in any group. Compared with TEA, low-dose remifentanil produced significantly higher plasma concentrations of noradrenaline and dopamine during pneumoperitoneum. Notwithstanding similar hemodynamic responses in all groups, only high-dose remifentanil suppressed both sympathetic responses and the hypothalamus-pituitary-adrenal axis. This result indicates that of these three anesthesia regimens, high-dose remifentanil seems most suited for laparoscopic surgery.