The effect of thiopental on cerebral blood flow, and its relation to plasma concentration, during simulated induction of anaesthesia in a porcine model

• The reversible effect of an induction dose of thiopental on the cerebral blood flow (CBF) was characterized by repeated 133Xe washout measurements during stable physiological conditions in anaesthetized pigs. A thiopental effect corresponding to induction of light and transient anaesthesia was confirmed by electroencephalography (EEG). The concentration (arterial plasma) -effect (-% CBF) relationship of thiopental was estimated using a sigmoidal Emax model. The injection caused a rapid 36 +/- 4.5% (mean +/- s.d.) drop in CBF, with return to baseline by 80 min. According to the pharmacodynamic model, the maximal effect of thiopental (Emax) in this experimental set-up was a 58% lowering of the CBF and the concentration at half-maximal effect (EC50) was 25 micrograms.ml-1. This study provides a complete characterization of the effect of thiopental on the CBF, including the time-course and concentration-effect relationship. A comparison to limited data in the literature suggests that the findings in the pigs constitute a fair approximation of the action of thiopental during the clinical induction of anaesthesia.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Anestesi och intensivvård (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Anesthesiology and Intensive Care (hsv//eng)

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