Fentanyl augments block of sympathetic responses to skin incision during sevoflurane anaesthesia in children.
We studied 61 healthy ASA 1 patients (aged 2-6 yr) to determine if fentanyl affects the minimum alveolar concentration which blocks adrenergic responses to skin incision (MAC-BAR) in 50% of children in the presence of 60% nitrous oxide. Patients were allocated randomly to one of three fentanyl groups to receive 0, 2 or 4 micrograms kg-1. Patients also received sevoflurane at a preselected end-tidal concentration according to an 'up-and-down' design. After a steady-state sevoflurane concentration had been maintained for at least 15 min, fentanyl was given i.v. Skin incision was performed 5 min after administration of fentanyl. The response was considered positive if heart rate (HR) or mean arterial pressure (MAP) increased by 15% or more. The MAC-BAR of sevoflurane was 1.45 MAC (95% confidence intervals 1.25-1.65 MAC), and this was reduced markedly to 0.63 MAC and 0.38 MAC by addition of fentanyl 2 and 4 micrograms kg-1, respectively. A ceiling effect was not observed and there was a significant difference between the 2 and 4 micrograms kg-1 groups.
Katoh
T
T
Department of Anaesthesiology and Intensive Care, Hamamatsu University School of Medicine, Japan.
Kobayashi
S
S
Suzuki
A
A
Kato
S
S
Iwamoto
T
T
Bito
H
H
Sato
S
S
D000759:Adjuvants, Anesthesia / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D062109:Dermatologic Surgical Procedures; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005283:Fentanyl / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008738:Methyl Ethers / Q000494:pharmacology*; D000077149:Sevoflurane
D000759:Adjuvants, Anesthesia; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D005283:Fentanyl