Low dose hyperbaric bupivacaine (0.5%) with three different doses of dexmedetomidine for spinal anesthesia in transurethral resection of the prostate: a randomized, double-blind trial

Background & Objectives: Transurethral resection of the prostate (TURP) is commonly performed under spinal anesthesia. The advent of bupivacaine replaced cinchocaine, hyperbaric bupivacaine became the favorite, as it offered prolonged effect and maneuverability of the position of the patient. The objective of this research was to assess the efficacy of three distinct concentrations of intrathecal dexmedetomidine in conjunction with 0.5% hyperbaric bupivacaine in TURP. Methods: This randomized, double-blind study included ninety patients aged 55 to 70 yr admitted for TURP. Patients were divided into three groups; Group A received 1.5 mL hyperbaric bupivacaine 0.5% plus 6 µg dexmedetomidine, Group B received 1.5 mL hyperbaric bupivacaine 0.5% plus 8 µg dexmedetomidine and Group C was administered 1.5 mL hyperbaric bupivacaine 0.5% plus 10 µg dexmedetomidine. The time to onset and duration of sensory and motor block were noted. Postoperatively, morphine was used for analgesia and time to first dose and the total consumption of morphine was noted in each patient. Pain was assessed at NRS scores at 6, 8, and 12 h. Results: An absence of statistically significant variation was noted at the onset and duration of sensory block and motor block between Groups A and B. Nevertheless, when comparing Group C to Groups A and B, the time to onset was considerably reduced (P < 0.05). The duration of first rescue analgesic was significantly prolonged in Groups C and B than in Group A, and in Group C than in Group B (P < 0.05). Postoperative total morphine consumption and NRS scores at 6, 8, and 12h were significantly reduced in Groups C and B compared to Group A; and in Group C than Group B (P < 0.05). Conclusions: Combined with hyperbaric bupivacaine, 10 µg of dexmedetomidine significantly prolongs analgesia duration, sensory block, and motor blockade in TURP, as compared to using dexmedetomidine in 6 µg or 8 µg with hyperbaric bupivacaine. This results in a reduction in the requirement of postoperative analgesics, but the incidence of adverse effects is comparable to the lower dosage regimens. Abbreviations: MAP: mean arterial pressure, NRS: Numeric Rating Scale, PACU: post-anesthesia care unit, SA: spinal anesthesia, TURP: Transurethral resection of the prostate. Keywords: Dose; Dexmedetomidine; Hyperbaric Bupivacaine; Pain; Spinal Anesthesia; Sensory Block; Transurethral Resection of the Prostate Citation: Mohamed RM, Abdelbadie M, Anwar AG. Low dose hyperbaric bupivacaine 0.5% with three different doses of dexmedetomidine for spinal anesthesia in transurethral resection of the prostate: A randomized, double-blind trial. Anaesth. pain intensive care 2025;29(3):384-391. DOI: 10.35975/apic.v29i3.2750 Received: May 22, 2024; Revised: January 26, 2025; Accepted: January 26, 2025