Attenuation of the haemodynamic response to placement of the Mayfield skull pin head holder: alfentanil versus scalp block

Abstract

Introduction : Application of the Mayfield clamp causes a significant haemodynamic response. Different methods have been used to attenuate this response. We compared two of these methods, namely alfentanil bolus (Group A) and nerve block of the scalp (Group B). Method : Twenty-two patients entered the study. Anaesthesia was standardised using thiopental, sufentanil, vecuronium, isoflurane, oxygen and air. Group A patients received alfentanil 10 mg kg -1 90 seconds before clamp placement and group B patients received a scalp block with lignocaine 4-5 mg kg -1 as a 1% solution after intubation. Blood pressure and pulse rate were recorded before, during and 30 s, 60 s, 120 s, 240 s and 480 s after clamp placement. Results : For group A, the mean maximum changes in systolic, diastolic and mean arterial blood pressure, and heart rate were, 34%, 39%, 35% and 20% respectively. The corresponding values for Group B were 9% (p=0, 004), 16% (p=0, 009), 13% (p=0, 0066) and 10% (p=0, 0901) respectively. Conclusion : The scalp block is significantly more effective in attenuating the blood pressure response to clamp placement (p<0.05).