EPIDURAL VERSUS INTRAVENOUS FENTANYL FOR REDUCING HORMONAL, METABOLIC, AND PHYSIOLOGICAL-RESPONSES AFTER THORACOTOMY

Background: Previous attempts to prevent all the unwanted postoperativ e responses to major surgery with an epidural hydrophilic opioid, morp hine, have not succeeded. The authors' hypothesis was that the lipophi lic opioid fentanyl, infused epidurally close to the spinal-cord opioi d receptors corresponding to the dermatome of the surgical incision, g ives equal pain relief but attenuates postoperative hormonal and metab olic responses more effectively than does systemic fentanyl. Methods: Forty patients were randomly assigned to receive either fentanyl epidu rally and saline intravenously, or fentanyl intravenously and saline e pidurally, in a double-blind fashion for the first 20 h after thoracot omy. For each patient, the fentanyl infusion was titrated to the rate required for pain relief (pain score < 3, maximum 10). Postoperative c hanges in blood pressure, heart rate, rectal temperature, and blood co ncentrations of adrenocorticotrophic hormone, beta-endorphin immunorea ctivity, cortisol, growth hormone, prolactin, glucose, and leukocytes were assessed. Results: Patients reported similar median pain scores, but the epidural group required about 40% less fentanyl than the intra venous group. Four hours postoperatively, the beta-endorphin immunorea ctivity concentrations were less in the epidural than in the intraveno us group. Plasma cortisol increased in a similar manner in both groups within 4 h of surgery, but the increase persisted to the next morning only in patients receiving intravenous fentanyl. Adrenocorticotropin, growth hormone, and prolactin responses were similar in both groups. The postoperative hyperglycemic response, leukocytosis, and blood pres sure were greater, and mean rectal temperature was lower, in the intra venous than in the epidural fentanyl group. Conclusions: The authors' results indicate that some aspects of the hormonal response to surgery are blocked more completely with epidural than with intravenous fenta nyl. Adequate pain relief with epidural fentanyl, with a smaller mean dose, ted to a smaller increase of some hormonal, metabolic, and physi ologic responses after thoracotomy than in association with the adequa te pain relief provided by intravenous fentanyl.