title: The effect of nitrous oxide on cerebral blood flow velocity in children anaesthetised with sevoflurane.
abstract: To determine the effects of nitrous oxide on middle cerebral artery blood flow velocity (CBFV) during sevoflurane anaesthesia in children, CBFV was measured using transcranial Doppler sonography in 16 ASA I or II children. Anaesthesia consisted of 1.0 MAC sevoflurane in 30% oxygen with intermittent positive pressure ventilation maintaining FEco2 at 38 mmHg (5.0 kPa) and a caudal epidural block using 0.25% bupivacaine 1.0 ml.kg-1. The remainder of the inspired gas was varied in one of two sequences either air/nitrous oxide/air or nitrous oxide/air/nitrous oxide. The results showed that CBFV decreased when nitrous oxide was replaced by air (p = 0.03) and returned to its initial value when nitrous oxide was reintroduced. CBFV increased when air was replaced by nitrous oxide (p = 0.04) and returned to its initial value when air was reintroduced. Mean heart rate and blood pressure remained constant. We conclude that nitrous oxide increases cerebral blood flow velocity in healthy children anaesthetised with 1.0 MAC sevoflurane.
authors.affiliation: Consultant in Paediatric Anaesthesia, Royal Hospital for Sick Children, Sciennes Road, Edinburgh EH9 1LF, UK. david.rowney@luht.scot.nhs.uk
authors.forename: D A
authors.initials: DA
authors.lastname: Rowney
authors.forename: R
authors.initials: R
authors.lastname: Fairgrieve
authors.forename: B
authors.initials: B
authors.lastname: Bissonnette
mesh_terms: D000388:Air; D019162:Anesthetics, Combined / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D002648:Child; D002675:Child, Preschool; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007223:Infant; D008738:Methyl Ethers / Q000494:pharmacology*; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D009609:Nitrous Oxide / Q000494:pharmacology*; D000077149:Sevoflurane; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D019162:Anesthetics, Combined; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane; D009609:Nitrous Oxide