Hemispheric‐synchronisation during anaesthesia: a double‐blind randomised trial using audiotapes for intra‐operative nociception control

Abstract

The possible antinociceptive effect of hemispheric‐synchronised sounds, classical music and blank tape were investigated in patients undergoing surgery under general anaesthesia. The study was performed on 76 patients, ASA 1 or 2, aged 18–75 years using a double‐blind randomised design. Each of the three tapes was allocated to the patients according to a computer‐generated random number table. General anaesthesia was standardised and consisted of propofol, nitrous oxide 66%/oxygen 33%, isoflurane and fentanyl. Patients breathed spontaneously through a laryngeal mask and the end‐tidal isoflurane concentration was maintained near to its minimum alveolar concentration value of 1.2%. Fentanyl was given intravenously sufficient to keep the intra‐operative heart rate and arterial blood pressure within 20% of pre‐operative baseline values and the fentanyl requirements were used as a measure of nociception control. Patients to whom hemispheric‐synchronised sounds were played under general anaesthesia required significantly less fentanyl compared with patients listening to classical music or blank tape (mean values: 28 μg, 124 μg and 126 μg, respectively) (p < 0.001). This difference remained significant when regression analysis was used to control for the effects of age and sex.