Bispectral index guided evaluation of propofol as anaesthetic adjuvant with isoflurane in patients undergoing craniotomy and excision of space occupying lesion: a randomized controlled double blind study

Background: Neuroprotection is the cornerstone of anaesthetic management in neurosurgery and is provided by both intravenous and inhaled anaesthetics. A combined technique with both agents may be easy to titrate, may allow to combine the neuroprotective effect of both, and reduce the anaesthetic dose used.
Aims and objectives: To evaluate propofol as anaesthetic adjuvant to Isoflurane in patients undergoing craniotomy and excision of space occupying lesion. The primary objective was to find out BIS guided optimum dose of propofol for infusion during intra operative course. The secondary objectives were to assess haemodynamic stability, reduction in requirement of opioids and isoflurane intra operatively, level of post operative sedation and any possible side effects.
Materials and Methods: Total 75 adult patients scheduled for craniotomy and excision of space occupying lesion under general anesthesia were recruited and divided randomly into three groups containing 25 patients each. Group A- maintenance dose of propofol @100 µg/kg/min iv.Group B- maintenance dose of propofol @150 µg/kg/min iv.Group C- maintenance infusion of TPN (20% intralipid) as placebo. Isoflurane was titrated to keep BIS between 40 to 60 and fentanyl(1µg/kg) was given if BIS value >60 despite isoflurane@1vol%. Haemodynamic parameters, reduction in requirement of opioids and isoflurane, level of post operative sedation (Ramsay Sedation Score) and any possible side effects were assessed.
Results: The requirement of Isoflurane (ISO Vol%) was significantly lesser in Groups-A&B as compared to Group-C at all the times during surgery. There was a decrease in mean MAP value followed by a gradual increase in all three groups, the decrease being much more in group-B as compared to groups-A&C. Patients given propofol infusions were calm and cooperative during extubation with stable haemodynamics and had earlier response to verbal commands.
Conclusions: Intraoperative infusion of propofol decreases requirement of inhalational agent and opioid analgesia significantly and patients are calm and cooperative during extubation with stable haemodynamics and early awakening. Propofol @100 µg/kg/min iv provides better haemodynamic stability.BIS is an indispensable tool in assessing intraoperative awareness and decreasing the requirement of inhalational agent.