Abstract

Background: Cerebral autoregulation (CA) continuously adjusts cerebrovascular resistance to maintain cerebral blood flow (CBF) constant despite changes in blood pressure. Also, CBF is proportional to changes in arterial carbon dioxide (CO2) (cerebrovascular CO2reactivity). Hypercapnia elicits cerebral vasodilation that attenuates CA efficacy, while hypocapnia produces cerebral vasoconstriction that enhances CA efficacy. In this study, we quantified the influence of sevoflurane anesthesia on CO2reactivity and the CA-CO2relationship. Methods: We studied patients with type 2 diabetes mellitus (DM), prone to cerebrovascular disease, and compared them to control subjects. In 33 patients (19 DM, 14 control), end-tidal CO2, blood pressure, and CBF velocity were monitored awake and during sevoflurane-based anesthesia. CA, calculated with transfer function analysis assessing phase lead (degrees) between low-frequency oscillations in CBF velocity and mean arterial blood pressure, was quantified during hypocapnia, normocapnia, and hypercapnia. Results: In both control and DM patients, awake CO2reactivity was smaller (2.8%/mm Hg CO2) than during sevoflurane anesthesia (3.9%/mm Hg; P<0.005). Hyperventilation increased CA efficacy more (3 deg./mm Hg CO2) in controls than in DM patients (1.8 deg./mm Hg CO2; P<0.001) in both awake and sevoflurane-anesthetized states. Conclusions: The CA-CO2relationship is impaired in awake patients with type 2 DM. Sevoflurane-based anesthesia does not further impair this relationship. In patients with DM, hypocapnia induces cerebral vasoconstriction, but CA efficacy does not improve as observed in healthy subjects.

Original languageEnglish
Pages (from-to)65-73
Number of pages9
JournalJournal of Neurosurgical Anesthesiology
Volume35
Issue number1
Early online date12 Aug 2021
DOIs
Publication statusPublished - 1 Jan 2023

Keywords

  • carbon dioxide/blood
  • cerebrovascular circulation/physiology
  • diabetes mellitus type 2
  • sevoflurane

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