Perioperative Medicine  |   November 2016
Distinct Cortical Signatures Associated with Sedation and Respiratory Rate Depression by Morphine in a Pediatric Population
Author Notes
  • From the Division of Respiratory Medicine, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada (S.L.C., F.C., E.J.P., I.N.); Faculty of Medicine, Department of Medicine, University of Toronto, Toronto, Ontario, Canada (G.M., R.L.H.); and Faculty of Medicine, Department of Physiology, University of Toronto, Toronto, Ontario, Canada (R.L.H.).
  • Submitted for publication January 6, 2016. Accepted for publication July 20, 2016.
    Submitted for publication January 6, 2016. Accepted for publication July 20, 2016.×
  • This article is featured in “This Month in Anesthesiology,” page 1A.
    This article is featured in “This Month in Anesthesiology,” page 1A.×
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    Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the digital files are provided in the HTML text of this article on the Journal’s Web site (www.anesthesiology.org).×
  • R.L.H. and I.N. are co-senior authors.
    R.L.H. and I.N. are co-senior authors.×
  • Address correspondence to Dr. Montandon: Departments of Medicine and Physiology, University of Toronto, Medical Sciences Building Room 3222, 1 King’s College Circle, Toronto, Ontario, Canada M5S 1A8. gaspard.montandon@utoronto.ca. Information on purchasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiology’s articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.
Article Information
Perioperative Medicine / Clinical Science / Central and Peripheral Nervous Systems / Pain Medicine / Pharmacology
Perioperative Medicine   |   November 2016
Distinct Cortical Signatures Associated with Sedation and Respiratory Rate Depression by Morphine in a Pediatric Population
Anesthesiology 11 2016, Vol.125, 889-903. doi:10.1097/ALN.0000000000001303
Anesthesiology 11 2016, Vol.125, 889-903. doi:10.1097/ALN.0000000000001303
Abstract

Background: Opioid analgesia is an essential component of perioperative care, but effective analgesia can be limited by excessive sedation and respiratory depression. The cortical signatures associated with sedation by opioids and the relationship between changes in cortical activity and respiratory function are not well understood. The objectives of this study were to identify the electroencephalogram signatures of sedation and respiratory changes induced by morphine in a pediatric population after elective surgery.

Methods: After otologic surgery, patients (14.8 ± 2.8 yr, n = 10) stayed overnight for pain relief with morphine (3 to 10 mg), hydration, and clinical observation. Electroencephalogram activity and polysomnography were performed before and after morphine, and electroencephalogram spectral properties and cardiorespiratory activities were analyzed.

Results: Compared to wakefulness and non–rapid eye movement sleep, morphine reduced high-frequency β1 (13.5 to 20 Hz) and β2 (20 to 30Hz) electroencephalogram powers (n = 10) and decreased coherence between frontal and occipital β2 electroencephalogram activities (n = 9), therefore indicating that morphine induced a deep sedative state. Morphine also reduced respiratory rate by 8.3% (n = 10). Interestingly, there was a significant correlation between the reduction in β1 electroencephalogram activity and the depression in respiratory rate induced by morphine (R = 0.715, n = 10). With significant reduction in β1 power, respiratory rate was decreased by more than 25%, suggesting that reduction in cortical arousal is associated with the severity of respiratory rate depression.

Conclusions: Analgesic doses of morphine are associated with reduction in respiratory rate when accompanied by reduction in β1 electroencephalogram power, indicating a powerful effect of cortical arousal state per se in respiratory rate depression by morphine.