Addition of intrathecal dexmedetomidine prolongs subarachnoid block in orthopaedic geriatric population undergoing unilateral TKR

Abstract

Background & Objective:  The analgesic efficacy of dexmedetomidine in patients undergoing different orthopaedic surgeries are well reported in studies.  However, the benefits of adding intrathecal dexmedetomidine to local anesthetics for prolonging the subarachnoid block in orthopaedic geriatric population is less documented.  This study was therefore aimed to compare the efficacy of adding intrathecal dexmedetomidine to local anesthetic and local anesthetic alone in prolonging the subarachnoid block in orthopaedic geriatric population undergoing unilateral TKR.

Methodology: This randomized control trial was conducted at the Department of Anesthesiology, Fauji Foundation Hospital, Rawalpindi from 1st April 2023 to 30th December 2023. A total of 60 geriatric patients undergoing unilateral TKR with physical status of class II & III (American Society of Anesthesiologists) were included in this study and randomized to 2 equal groups. In Group A, patients received intrathecal 0.5% hyperbaric bupivacaine with 0.2 mL of dexmedetomidine (5 ?g), while in Group B, no additional drug was given besides 0.5% hyperbaric bupivacaine.

The primary outcomes were set as time duration for the first analgesia requirement, postoperative pain score at rest, and movement at 24-hour follow up while the secondary outcomes were duration of motor and sensory blockade.

Results: The Mean±SD of age in this study was 68.03±4.54 years with an age range of 60 to 76 years. The ratio of male gender was 60% while female gender was 40%. Primary outcomes of the study show that the mean time to need rescue analgesia was significantly longer in Group A compared to Group B (461.37±21.52 Vs 330.91±18.21 Min, p=0.000 ). Similarly, the mean pain scores at rest (3.29±1.78 Vs 4.86±1.52, p=0.000) and at movement (5.1±1.60 Vs 6.44±1.42, p=0.001) were significantly less in Group-A compared to Group-B. The results of secondary outcomes also showed a prolonged duration of sensory and motor blocks in Group A compared to Group B (379.52±63.74 Vs 304.76±17.67, p=0.000 and 390.03±67.23 Vs 259.8±17.62, p=0.000, respectively).

Conclusions: The addition of intrathecal dexmedetomidine to local anesthetic prolongs the subarachnoid block and results in a prolonged duration of need for rescue analgesia and reduces the mean pain score at rest and movement in patients undergoing unilateral TKR.