Brief infant general anesthesia leaves neurodevelopment unaffected

  • McCann ME & al.
  • Lancet
  • 16 Feb 2019

  • curated by Emily Willingham, PhD
  • Clinical Essentials
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  • Infants who have less than 1 hour of general anesthesia show no effects on neurodevelopment at age 5 years compared with peers who have awake-regional anesthesia.
  • Most of the infants in the GAS Trial were male; all had inguinal herniorrhaphy performed.

Why this matters

  • Some (but not all) cohort studies have suggested an effect of early general anesthesia. 
  • This study was a randomized controlled trial.

Key results

  • General anesthesia median duration, 54 (interquartile range, 41-70) minutes.
  • Mean IQ scores were 99.08 (standard deviation [SD], 18.35) with awake-regional vs 98.97 (SD, 19.66) with general anesthesia.
    • Mean difference, 0.23 (95% CI, −2.59 to 3.06).
  • Above were for per-protocol analysis; intention-to-treat analysis yielded similar results (mean difference in IQ, 0.16 [95% CI, −2.45 to 2.78]).
  • Values were within prespecified 5-point margin for outcome equivalence.
  • Anesthesia-concurrent adverse events were all respiratory complications.

Study design

  • International (US, Canada, UK, New Zealand, Australia, the Netherlands, Italy) randomized, controlled, assessor-masked equivalence trial.
  • n=722 infants, randomly allocated to awake-regional anesthesia (363) and general anesthesia (sevoflurane; 359).
  • Per-protocol analysis involves 205 and 242 infants, respectively.
  • Primary outcome: full-scale IQ at age 5 years.
  • Funding: NIH, institutions in the various countries.


  • Involves specific, narrow developmental windows for intervention, assessment.

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