Related Experiment Video
Updated: Aug 18, 2026

Determining heat and mechanical pain threshold in inflamed skin of human subjects
Published on: January 14, 2009
Segmental analgesic effect and reduction of halothane MAC from epidural fentanyl in humans
Y Inagaki1, T Mashimo, I Yoshiya
1Department of Anesthesiology, Osaka University Medical School, Japan.
Abstract:
To clarify the site of action of epidural fentanyl, we compared the effects of epidural and intravenous fentanyl on the change in pressure pain threshold (PPT) and the minimum alveolar concentration (MAC) of halothane. Seventy patients who underwent gastrectomy in the PPT study group and 84 female patients who underwent hysterectomy in the MAC study group were assigned randomly to seven groups in each study. The seven groups each received a bolus injection of 1, 2, or 4 micrograms/kg of fentanyl, either intravenously or epidurally, and of saline solution epidurally. Compared with intravenous fentanyl, epidural fentanyl significantly increased (P less than 0.01) PPT around surgical incisions by approximately 50%, 100%, and 150% of preadministration levels 1 h after administration of 1, 2, and 4 micrograms/kg, respectively, and significantly reduced (P less than 0.05) halothane MAC at the same doses. These data suggest that the more potent analgesic and anesthetic effects of epidural fentanyl, compared with intravenous fentanyl, are due mainly to the segmental analgesia produced by its spinal analgesic action.
More Related Videos
Related Concept Videos
Local Anesthetics: Clinical Application as Spinal Anesthesia
Local Anesthetics: Clinical Application as Epidural Anesthesia
Since epidural anesthetics can be infused through an epidural catheter, all types of drugs, including short-acting ones, can be administered. Chloroprocaine and lidocaine are examples of short and long-duration anesthetics, respectively. Bupivacaine...
Analgesia and Pain Management
General Anesthesia: Overview
General anesthesia induces unconsciousness in the whole body, while the others target specific areas or sensations. It is administered to minimize adverse effects, maintain...
Parenteral Anesthetics: Overview
Inhalational Anesthetics: Overview

