Addition of Intrathecal Dexmedetomidine Prolongs Subarachnoid Block in Orthopaedic Geriatric Population Undergoing Unilateral TKR

Objective: To evaluate and compare the efficacy of intrathecal dexmedetomidine as an adjuvant to local anesthetic versus local anesthetic alone in prolonging subarachnoid block among geriatric patients undergoing unilateral total knee replacement (TKR). Methodology: This randomized controlled trial was conducted in the Department of Anesthesiology, Fauji Foundation Hospital, Rawalpindi, from April 1, 2023, to December 30, 2023. A total of 60 geriatric patients (aged ?60 years) with American Society of Anesthesiologists (ASA) physical status class II or III, scheduled for unilateral TKR, were enrolled and randomized into two equal groups. Primary outcomes included the time to first analgesic requirement and postoperative pain scores at rest and during movement at 24 hours. Secondary outcomes assessed were the duration of sensory and motor blockade. Results: The mean age of participants was 68.03 ± 4.54 years (range: 60–76 years), with 60% males and 40% females. Group A demonstrated a significantly prolonged time to rescue analgesia compared to Group B (461.37 ± 21.52 vs. 330.91 ± 18.21 minutes; p = 0.000). Postoperative pain scores were significantly lower in Group A both at rest (3.29 ± 1.78 vs. 4.86 ± 1.52; p = 0.000) and during movement (5.10 ± 1.60 vs. 6.44 ± 1.42; p = 0.001). Furthermore, Group A showed a significantly longer duration of sensory block (379.52 ± 63.74 vs. 304.76 ± 17.67 minutes; p = 0.000) and motor block (390.03 ± 67.23 vs. 259.80 ± 17.62 minutes; p = 0.000) when compared to Group B. 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.