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Cerebrovascular responses to carbon dioxide in children anaesthetized with halothane and isoflurane

J E Leon1, B Bissonnette

  • 1Department of Anaesthesia, Hospital for Sick Children, University of Toronto, Ontario, Canada.

Canadian Journal of Anaesthesia = Journal Canadien D'Anesthesie
|October 1, 1991
PubMed

Insights

Isoflurane and halothane anesthesia in children do not significantly alter cerebrovascular reactivity to carbon dioxide (CO2). This suggests both anesthetics maintain normal brain blood flow regulation in young patients up to 1.0 minimum alveolar concentration (MAC).

Area of Science:

  • Anesthesiology
  • Pediatric Neurology
  • Cerebrovascular Physiology

Background:

  • Maintaining adequate cerebral blood flow and reactivity to carbon dioxide (CO2) is crucial during pediatric anesthesia.
  • Isoflurane and halothane are commonly used volatile anesthetics in children, but their precise effects on cerebrovascular reactivity require clarification.

Purpose of the Study:

  • To investigate the impact of isoflurane and halothane on the cerebrovascular reactivity to CO2 in anesthetized children.
  • To compare the effects of different concentrations (0.5 and 1.0 minimum alveolar concentration [MAC]) of these anesthetics on cerebral blood flow velocity (CBFV) and cerebrovascular resistance.

Main Methods:

  • Thirty children (aged 1-6 years) were anesthetized with isoflurane or halothane.
  • End-tidal carbon dioxide tension (PETCO2) was adjusted to 20, 40, and 60 mmHg at steady-state anesthetic concentrations (0.5 and 1.0 MAC).
  • Cerebral blood flow velocity (CBFV) and cerebrovascular resistance index (RI+) in the middle cerebral artery (MCA) were measured using transcranial Doppler.

Main Results:

  • Both isoflurane and halothane demonstrated a significant increase in CBFV with rising PETCO2 at both 0.5 and 1.0 MAC (P < 0.05).
  • Isoflurane showed a consistent CBFV increase with PETCO2 from 20 to 60 mmHg.
  • Halothane showed a significant CBFV increase from 20 to 40 mmHg PETCO2, but not from 40 to 60 mmHg. RI+ showed an inverse relationship with CBFV. No significant differences in CBFV were observed between anesthetic types or MAC levels at corresponding PETCO2.

Conclusions:

  • Isoflurane and halothane, up to 1.0 MAC, do not impair the cerebrovascular reactivity to CO2 in healthy, anesthetized children.
  • These findings support the continued use of isoflurane and halothane in pediatric anesthesia while maintaining normal cerebral autoregulation.

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