Effect of sevoflurane on cerebral blood flow and cerebrovascular resistance at surgical level of anaesthesia: a transcranial Doppler study.
OBJECTIVE
It is widely accepted that sevoflurane affects cerebral circulation, but there are uncertainities regarding the magnitude of its effect. The aim of the present work was to assess the effect of sevoflurane on the cerebral circulation at surgical levels of anaesthesia.


METHODS
Twenty patients undergoing elective lumbar discectomies were investigated. Anaesthesia was induced with propofol and maintained with sevoflurane. The level of surgical anaesthesia was determined by bispectral index, the target level was 45-55. Transcranial Doppler (TCD) measurement was performed before induction and after reaching the surgical level of anaesthesia. Besides routine parameters (middle cerebral artery mean blood flow velocity (MCAV) and pulsatility index (PI)) derived parameters (estimated cerebral perfusion pressure (eCPP), cerebral blood flow index (CBFI) and resistance area product (RAP)) were calculated by taking changes of mean arterial pressure also into account.


RESULTS
MCAV decreased from 54.1 +/- 13.3 to 43.7 +/- 18.5 cm s-1, P < 0.01 and PI increased from 0.79 +/- 0.2 to 0.92 +/- 0.2, P < 0.01 after reaching the surgical level of anaesthesia. As a result eCPP decreased by 18.2%, CBFI by 25.5% and RAP increased by 15% respectively.


CONCLUSIONS
Our data indicate a vasodilatory effect of sevoflurane at surgical level of anaesthesia on large cerebral vessels or a vasoconstriction of the resistance arterioles likely caused by decreased brain metabolism.
Molnár
C
C
Department of Anesthesiology and Intensive Care, Health and Medical Science Centre, University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary.
Settakis
G
G
Sárkány
P
P
Kálmán
S
S
Szabó
S
S
Fülesdi
B
B
D000328:Adult; D000768:Anesthesia, General / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D017558:Elective Surgical Procedures / Q000379:methods; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008738:Methyl Ethers / Q000494:pharmacology*; D000077149:Sevoflurane; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*; D014655:Vascular Resistance / Q000187:drug effects*
D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane