Effect of small dose intravenous dexmedetomidine and/or local anaesthetic infiltration on haemodynamic responses to skull pin placement

ABSTRACT

Fixation of skull pins during craniotomy may cause acute haemodynamic changes. We evaluated, in this randomised double blind placebo controlled trial, the effects of small dose of dexmedetomidine [Dex] infusion in attenuating the haemodynamic profile during skull pin placement. Twenty-eight patients ASA I and II undergoing elective craniotomy were studied. Anaesthesia induced with sufentanil and sodium thiopentone [STP]. Cisatracurium was given to facilitate endotracheal intubation. Patients were randomly allocated to one of four groups [each 7 patients] dex, lidocaine, dex-lidocaine and placebo [groups I, II, III, and IV respectively]. Groups I and III received intravenous Dex 0.25 meg/kg infusion and local infiltration with normal saline [NS] in group I and with 1% lidocaine in group III. Groups II and IV received intravenous NS and local infiltration at each pin insertion site with 1% lidocaine in group II and NS in group IV. The protocol started with intravenous medications to the assigned groups followed [after 8 min] with local infiltration of the scalp. Two minutes later [10 min after intravenous medication], scalp pinning was performed. Variables recorded were heart rate [HR], systolic blood pressure [SBP] and mean blood pressure [MBP] at different times. After opening the dura, brain status was assessed by the surgeon. Repeated measures of variance of HR, SBP, and MBP showed statistically significant interaction between group assignment and assigned time for groups I and III. In conclusion, our results showed that use of small doses of dex has resulted in obtunding the haemodynamic response to skull pin placement