A Comparative Study of Intrathecal Hyperbaric Bupivacaine With Fentanyl Versus Intrathecal Hyperbaric Bupivacaine With Dexmedetomidine Administered Sequentially for Lower Limb Orthopaedic Surgeries: A Prospective Randomised Double-Blind Study.

BACKGROUND

The subarachnoid block is the predominant and relatively safe approach during lower limb orthopaedic operations. When used as an additive to intrathecal local anaesthetic, both fentanyl and dexmedetomidine can extend the duration of sensory and motor blockade and improve postoperative analgesia.

OBJECTIVES

The objective of this study is to assess and compare the efficacy of sequential administration of fentanyl and dexmedetomidine alongside 0.5% hyperbaric bupivacaine intrathecally in lower limb orthopaedic surgeries, focussing on block characteristics, postoperative analgesia as measured by visual analogue scale (VAS) scores, haemodynamic changes, and adverse effects.

MATERIALS AND METHODS

Sixty patients were randomised into two groups of 30 each. Group A received 15 mg of 0.5% hyperbaric bupivacaine followed by 25 µg of fentanyl, whereas group B received 15 mg of 0.5% hyperbaric bupivacaine followed by 5 µg of dexmedetomidine, administered sequentially for spinal anaesthesia.

RESULTS

Patients in group B exhibited a markedly prolonged sensory and motor block duration compared to group A. The duration required to achieve maximum sensory blockage (T6) was reduced significantly in group B (2.40 ± 0.50 minutes) compared to group A (5.03 ± 0.81 minutes). The average duration of sensory regression to S1 was 207.33 ± 20.18 minutes in group B and 146.57 ± 19.01 minutes in group A (p < 0.001). Patients in group B exhibited a markedly prolonged sensory and motor block duration compared to group A. The duration to attain total motor blockage (Modified Bromage 3) was markedly reduced in group B (4.23 ± 0.68 minutes) relative to group A (7.03 ± 0.81 minutes). The overall analgesic required over a 24-hour period and the average VAS ratings were both lower in group B compared to group A. Additionally, patient satisfaction was higher in group B (207.33 ± 20.18 minutes) than in group A (146.57 ± 19.01 minutes) (p < 0.001).

CONCLUSION

The study concludes that the sequential administration of dexmedetomidine as an adjuvant with the local anaesthetic agent during the subarachnoid block enhances the onset of sensory and motor block, prolongs analgesia, diminishes overall analgesic requirements, increases patient satisfaction, and maintains stable haemodynamics compared to fentanyl. Bradycardia is common with dexmedetomidine.