Newly Published
Perioperative Medicine  |   September 2019
δ-Oscillation Correlates of Anesthesia-induced Unconsciousness in Large-scale Brain Networks of Human Infants
Author Notes
  • From the Division of Anesthesia, Department of Clinical Neurosciences, University of Cambridge, Addenbrooke’s Hospital, Cambridge, United Kingdom (I.P., D.K.M., E.A.S.); and the Department of Anesthesiology, Critical Care and Pain Medicine, Boston Children’s Hospital, Boston, Massachusetts (L.C., C.B.B.) and Department of Anesthesia, Harvard Medical School, Boston, Massachusetts (L.C., C.B.B.). Current affiliations: Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, California (I.P.).
  • I.P. and L.C. contributed equally to this article.
    I.P. and L.C. contributed equally to this article.×
  • Submitted for publication December 4, 2018. Accepted for publication August 15, 2019.
    Submitted for publication December 4, 2018. Accepted for publication August 15, 2019.×
  • Correspondence: Address correspondence to Dr. Pappas: University of Cambridge, Cambridge, United Kingdom. ip322@cam.ac.uk 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 / Central and Peripheral Nervous Systems / Pediatric Anesthesia
Perioperative Medicine   |   September 2019
δ-Oscillation Correlates of Anesthesia-induced Unconsciousness in Large-scale Brain Networks of Human Infants
Anesthesiology Newly Published on September 18, 2019. doi:10.1097/ALN.0000000000002977
Anesthesiology Newly Published on September 18, 2019. doi:10.1097/ALN.0000000000002977
Abstract

Editor’s Perspective:

What We Already Know about This Topic:

  • Electroencephalographic α-oscillations in the frontal cortex do not appear during general anesthesia in infants less than 3 to 4 months old

  • In adults, functional connectivity and brain network integration appear to break down during anesthesia but whether this is true in infants is unknown

What This Article Tells Us That Is New:

  • In infants younger than four months, slow-wave functional connectivity breaks down during general anesthesia and brain networks are less integrated

  • Functional disconnections in the cortex might be a common marker of anesthesia-induced unconsciousness in infants and adults

Background: Functional brain connectivity studies can provide important information about changes in brain-state dynamics during general anesthesia. In adults, γ-aminobutyric acid–mediated agents disrupt integration of information from local to the whole-brain scale. Beginning around 3 to 4 months postnatal age, γ-aminobutyric acid–mediated anesthetics such as sevoflurane generate α-electroencephalography oscillations. In previous studies of sevoflurane-anesthetized infants 0 to 3.9 months of age, α-oscillations were absent, and power spectra did not distinguish between anesthetized and emergence from anesthesia conditions. Few studies detailing functional connectivity during general anesthesia in infants exist. This study’s aim was to identify changes in functional connectivity of the infant brain during anesthesia.

Methods: A retrospective cohort study was performed using multichannel electroencephalograph recordings of 20 infants aged 0 to 3.9 months old who underwent sevoflurane anesthesia for elective surgery. Whole-brain functional connectivity was evaluated during maintenance of a surgical state of anesthesia and during emergence from anesthesia. Functional connectivity was represented as networks, and network efficiency indices (including complexity and modularity) were computed at the sensor and source levels.

Results: Sevoflurane decreased functional connectivity at the δ-frequency (1 to 4 Hz) in infants 0 to 3.9 months old when comparing anesthesia with emergence. At the sensor level, complexity decreased during anesthesia, showing less whole-brain integration with prominent alterations in the connectivity of frontal and parietal sensors (median difference, 0.0293; 95% CI, −0.0016 to 0.0397). At the source level, similar results were observed (median difference, 0.0201; 95% CI, −0.0025 to 0.0482) with prominent alterations in the connectivity between default-mode and frontoparietal regions. Anesthesia resulted in fragmented modules as modularity increased at the sensor (median difference, 0.0562; 95% CI, 0.0048 to 0.1298) and source (median difference, 0.0548; 95% CI, −0.0040 to 0.1074) levels.

Conclusions: Sevoflurane is associated with decreased capacity for efficient information transfer in the infant brain. Such findings strengthen the hypothesis that conscious processing relies on an efficient system of integrated information transfer across the whole brain.