ABSTRACT
BACKGROUND AND 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.
Subject(s)
Anesthesia, General/methods , Anesthetics, Inhalation/pharmacology , Cerebrovascular Circulation/drug effects , Methyl Ethers/pharmacology , Ultrasonography, Doppler, Transcranial/methods , Vascular Resistance/drug effects , Adult , Blood Flow Velocity/drug effects , Blood Pressure/drug effects , Elective Surgical Procedures/methods , Electroencephalography/methods , Female , Heart Rate/drug effects , Humans , Lumbar Vertebrae/surgery , Male , SevofluraneABSTRACT
Pathologic processes affecting the brain vessels may damage cerebral vasodilatory capacity. Early detection of cerebral dysfunction plays an important role in the prevention of cerebrovascular diseases. In recent decades acetazolamide (AZ) has frequently been used for this purpose. In the present work the mechanism of action and the previous studies are reviewed. The authors conclude that AZ tests are useful in cerebrovascular research. Further investigations are recommended to prove how impaired reserve capacity and reactivity influence the stroke risk in patients and whether these tests may indicate therapeutic interventions.
Subject(s)
Acetazolamide/therapeutic use , Cerebrovascular Disorders/drug therapy , Vasodilator Agents , Aging/physiology , Animals , Cerebrovascular Disorders/physiopathology , Dose-Response Relationship, Drug , Homeostasis/physiology , Humans , Sex Characteristics , Stroke/drug therapy , Stroke/physiopathologyABSTRACT
Twenty-five healthy and thirty-one preeclamptic pregnant women were assessed by means of transcranial Doppler sonography. Resting cerebral blood flow velocities in the middle cerebral arteries were measured followed by a repeat measurement 30 s after breath holding. Absolute blood flow velocities and per cent changes after breath holding procedure were compared between the groups. Absolute blood flow velocities were higher in preeclamptic pregnant women both at rest and after breath holding. The percent increase in cerebral blood flow velocity after breath holding (cerebral vascular reactivity) was similar in the two groups. Our data suggest that cerebral vascular reactivity is preserved in pregnant women with preeclampsia.