EFFECT OF SCALP INFILTRATION WITH BUPIVACAINE ON ANALGESIC REQUIREMENT FOLLOWING CRANIOTOMY

Abstract

BACKGROUND: The main focus in neurosurgery and neuroanaesthesia has always been
towards the preservation of neural function rather than on pain and its impact on the patient’s
welfare. Inadequate pain management elicits a stress response which has numerous adverse
effects on patients clinically, especially on the intracranial pressure, hence the need to search for
cheaper and effective means of pain control following craniotomy.
PATIENTS AND METHODS: Following ethical approval from the hospital’s Ethics
Committee, 50 consenting adult patients scheduled for craniotomy under general anaesthesia
were randomly allocated to one of two study groups: “A” and “B” for scalp infiltration
immediately post craniotomy. All patients received standard general anaesthesia with fentanyl,
sodium thiopentone or propofol, atracurium and 100% oxygen in isoflurane. At skin closure, the
surgeon infiltrated the scalp with either 20 ml of 0.25% plain bupivacaine (Group A, bupivacaine
group), or 20 ml normal saline (Group B, saline group). Pain scores were assessed using visual
analogue scale (VAS) on admission into the intensive care unit (ICU) then at 4, 8, 12, 16, 20, 24
and 48 hours after surgery. The interval between end of surgery and first request for analgesia, 4
hourly interval pentazocine as well as the cumulative doses of pentazocine given for post
operative pain relief were recorded.
RESULTS: The visual analogue score (VAS) at the time of admission into ICU was
significantly lower in bupivacaine group with a mean score of 2.56 (±0.67) compared to
4.03(±0.83) for patients in saline group, (P = 0.0001). There was, however, no statistically
significant difference in VAS score at 4, 8, 12, 16, 20, 24 and 48 hours postoperatively.
There was a statistically significant increase in the time to first analgesic (TFA) request between
the two groups with bupivacaine group having a mean time of 139.44 (±25.16) minutes and
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saline group 80.48 (±18.77) minutes, P-value = 0.0001. There was also less cumulative
pentazocine consumption at 48 hours postoperatively, with patients in bupivacaine group having
mean consumption of 208.80(±16.16) mg compared to the saline group, 242.40 (±19.21) mg. P
value = 0.0001. Also observed was a trend towards reduced incidence of sedation and
postoperative nausea and vomiting in the bupivacaine group compared to saline group. No
complications were recorded from the infiltration procedure or local anaesthetic toxicity.
CONCLUSIONS: Post-operative scalp infiltration with plain bupivacaine 0.25% reduces pain
intensity and opioid analgesic consumption; hence it is effective in improving pain management
after craniotomy.