Open AccessThe Effects of Sevoflurane and Nitrous Oxide on Middle Cerebral Artery Blood Flow Velocity and Transient Hyperemic Response
Author(s) -
N. Bedforth,
Keith J. Girling,
J. M. Harrison,
Ravi Mahajan
Publication year - 1999
Publication title -
anesthesia and analgesia/anesthesia and analgesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.404
H-Index - 201
eISSN - 1526-7598
pISSN - 0003-2999
DOI - 10.1097/00000539-199907000-00030
Subject(s) - sevoflurane , medicine , anesthesia , middle cerebral artery , nitrous oxide , cerebral blood flow , cerebral autoregulation , propofol , autoregulation , blood pressure , ischemia
We studied the effects of sevoflurane, with and without nitrous oxide, on the indices of cerebral autoregulation (transient hyperemic response ratio and the strength of autoregulation) derived from the transient hyperemic response (THR) test. Twelve patients (ASA physical status I or II) aged 18-40 yr presenting for routine non-neurosurgical procedures were recruited. The middle cerebral artery blood flow velocity was continuously recorded using transcranial Doppler ultrasonography. Preinduction THR tests were performed before the patients were anesthetized with alfentanil, propofol, and vecuronium. End-tidal carbon dioxide concentration and mean arterial pressure (to within 10% with a phenylephrine infusion) were maintained at their preinduction values. THR tests were performed sequentially at the following end-tidal sevoflurane concentrations: 2.2% in oxygen, 3.4% in oxygen, 3.4% with 50% nitrous oxide in oxygen, and 2.2% with 50% nitrous oxide in oxygen. Neither 2.2% nor 3.4% sevoflurane significantly affected cerebral autoregulation. The addition of 50% nitrous oxide to the 2.2%, but not the 3.4%, concentration of sevoflurane increased middle cerebral artery blood flow velocity and decreased autoregulatory indices significantly.