Effects of dexmedetomidine on isoflurane requirements in healthy volunteers. 2: Auditory and somatosensory evoked responses

• Published in: British Journal of Anaesthesia Vol. 83; no. 3; pp. 381 - 386
• Main Authors: Thornton, C, Lucas, M A, Newton, D E, Doré, C J, Jones, R M
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01-09-1999; Oxford University Press; Oxford Publishing Limited (England)
• Subjects: Adrenergic alpha-Agonists - pharmacology; Adult; Anesthetics, Inhalation - pharmacology; Anesthetics. Neuromuscular blocking agents; Biological and medical sciences; Dexmedetomidine - pharmacology; Dose-Response Relationship, Drug; Drug Interactions; Evoked Potentials - drug effects; Evoked Potentials, Auditory - drug effects; Evoked Potentials, Somatosensory - drug effects; Humans; Isoflurane - pharmacology; Male; Medical sciences; Neuropharmacology; Pharmacology. Drug treatments; Volatile compound; Human; α2-Adrenergic receptor; Agonist; Drug combination; General anesthesia; Isoflurane; Dose activity relation; Electrodiagnosis; General anesthetic; Auditory evoked potential; Dexmedetomidine; Drug interaction; Somatosensory evoked potential; Monitoring; Halogen Organic compounds; Premedication
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/83.3.381

The anaesthetic-sparing activity of dexmedetomidine during isoflurane anaesthesia was examined, using the end-point of lack of response to tetanic nerve stimulation. Nine subjects were given two doses of dexmedetomidine (target plasma concentrations of 0.3 ng ml-1 and 0.6 ng ml-1, respectively) and saline on separate occasions. We measured auditory (AER) and somatosensory (SER) evoked responses at end-tidal isoflurane concentrations of 0.2-1.4%. Pa and P25-N35 amplitudes increased as isoflurane concentration was reduced (P < 0.001). Dexmedetomidine had no significant effect on this relationship. In contrast, P15-N20 (SER) amplitude increased (P < 0.001) as isoflurane concentration was reduced. The dose of dexmedetomidine had a significant interaction with this trend (P < 0.002). Decreasing the concentration of isoflurane at the high dose of dexmedetomidine had less impact on P15-N20 amplitude than decreasing isoflurane at the low dose or with saline. The mechanism by which dexmedetomidine spares isoflurane is discussed in the light of these evoked response changes.