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ABSTRACT
Introduction: Skull pin placement in neurosurgical procedures
can cause acute nociceptive stimuli that may result in an acute
haemodynamic response and rise in intracranial pressures. Pain
management is crucial to treat this detrimental stimulus.
Aim: To compare the effects of dexmedetomidine as a local
anaesthetic adjuvant to bupivacaine versus bupivacaine alone
in scalp block for attenuation of haemodynamic response to
skull pin placement in neurosurgical procedures.
Materials and Methods: A double-blinded randomised controlled
study was done at St. John’s Medical College Hospital, Bengaluru,
Karnataka, India where 70 patients were randomly placed into one of
two groups (35 each). Patients in Group D received scalp block with
1 μg/kg dexmedetomidine and 25 mL of 0.25% bupivacaine. Group
C received 25 mL of 0.25% bupivacaine alone. Heart Rate (HR),
Systolic Blood Pressure (SBP), Diastolic Blood Pressure (DBP), and
Mean Arterial Pressure (MAP) were recorded at baseline and at 1,
3, 5, 10 and 15 minutes post scalp block. Haemodynamic changes
were analysed using the unpaired Student’s t-test in both groups.
Results: Demographic variables including age, gender, weight
and American Society of Anaesthesiologists (ASA) status were
comparable between the groups. A significant increase in HR
from baseline to one and three minutes after scalp block in both
groups (-6.89 beats/min, p-value=0.001 and -4.89 beats/min,
p-value=0.049 in Group D; -8.4 beats/min, p-value <0.001 and
-7.34 beats/min, p-value <0.001 in Group C, respectively). There
was also significant decrease in HR from baseline to 15 minutes
after scalp block (4.8 beats/min, p-value=0.006) in Group D. In
both groups, there was a clinical increase in BP from baseline to 1
and 3 minutes after scalp block (Group D baseline MAP 86.5±7.1
mmHg, at 1 minute 90.5±7.5 mmHg, at 3 minutes 89.2±6.5mmHg;
Group C baseline MAP 89.5±8.7 mmHg, at one minute 92.7±9.0
mmHg, and at three minutes 92.0±7.9 mmHg). After 10 and 15
minutes of scalp block, the mean BP of the patients in Group D
(84.9±5.8 mmHg and 83.9±5.7 mmHg) was significantly lesser
as compared to that of patients in Group C (88.9±8.8 mmHg and
87.9±8.8 mmHg).
Conclusion: Scalp nerve block is extensively used for
intraoperative haemodynamic stability and opioid-sparing
effects. It has proven to provide better postoperative analgesia
in patients undergoing craniotomies. In present study, the
addition of 1 μg/kg of dexmedetomidine with 25 mL of 0.25%
bupivacaine for a scalp block minimises the haemodynamic
response to skull pin placement when compared to 0.25%
bupivacaine given alone in patients undergoing craniotomies
for Central Nervous System (CNS) pathologies.