Comparative study between intravenous and intrathecal dexmedetomidine in spinal anaesthesia in patients undergoing elective infra-umbilical surgery: the effect on postoperative analgesia and haemodynamic parameters

BackgroundManagement of postoperative pain is crucial to reduce central, peripheral, and immunological stress response. α2- adrenergic receptor agonists are commonly used as an adjuvant to intrathecal local anaesthetics to improve postoperative analgesia.ObjectivesWe compared intravenous versus intrathecal dexmedetomidine as an adjuvant to hyperbaric bupivacaine in patients undergoing elective infra-umbilical surgeries in supine position under spinal anaesthesia.Methodology100 patients randomized to two groups (50 each).for spinal anaesthesia with hyperbaric bupivacaine, intrathecally received 3.5ml [3ml (15mg bupivacaine) in both groups +0.5ml (saline versus 5μg dexmedetomidine in saline in Group A, B respectively)] .Slow intravenous infusion of 1μg/kg dexmedetomidine in 50ml saline versus 50ml saline was given to Group A and B respectively ten minutes before blockade.ResultsPatients receiving intrathecal dexmedetomidine had a significantly longer motor and sensory blockade than those receiving intravenous dexmedetomidine (253.80±20.94 vs. 205.00±19.08; P<0.001) and (230.48±17.21 vs. 181.48±21.12; P<0.001) respectively. The intensity of pain was significantly lower in group B especially at t6 and t12. The total consumption of rescue analgesia was less in group B when compared to group A (100.30±21.63mg vs. 135.80±23.02mg respectively, P= 0.000). The incidence of hypotension was greater in the intravenous group with no statistical significance (34.0% vs 26.0%; P>0.05).ConclusionsThe addition of 5 μg dexmedetomidine to 0.5% hyperbaric bupivacaine intrathecally can provide a better quality of postoperative analgesia with no significant side effects as compared to intravenous dexmedetomidine.