Dexmedetomidine Versus Fentanyl as an Adjuvant to 0.75% Ropivacaine in Ultrasound-Guided Infraclavicular Brachial Plexus Block: An Observational Study.

Background Peripheral nerve blockade is increasingly used in upper limb orthopedic surgery to provide effective anesthesia and prolonged postoperative analgesia while reducing systemic opioid requirements. Ultrasound-guided infraclavicular brachial plexus block provides reliable anesthesia for surgeries of the elbow, forearm, wrist, and hand, and adjuvants are frequently added to local anesthetics to improve block quality and prolong analgesia. Dexmedetomidine and fentanyl are two such adjuvants, but their comparative effects on onset, duration, and quality of blockade remain unclear. This observational study compared dexmedetomidine and fentanyl as adjuvants to ropivacaine in ultrasound-guided infraclavicular brachial plexus block. Methodology A prospective observational study was conducted in the Department of Anaesthesiology, Adichunchanagiri Institute of Medical Sciences, over 18 months from November 2016 to April 2018. Sixty eligible patients aged 18 to 65 years, of ASA physical status I or II, undergoing elective upper limb orthopedic surgery under ultrasound-guided infraclavicular brachial plexus block were enrolled consecutively and observed across two exposure groups of 30 each, categorized according to the adjuvant selected by the treating anesthesiologist as part of routine clinical practice. Group A received ropivacaine 0.75% (30 mL) with dexmedetomidine 50 micrograms, while Group B received ropivacaine 0.75% (30 mL) with fentanyl 75 micrograms, under ultrasound guidance. Sensory blockade was assessed by the pinprick method and motor blockade by the modified Bromage scale. Heart rate, blood pressure, and oxygen saturation were monitored, and adverse effects were recorded. Results Baseline demographic and clinical characteristics were comparable between the two groups, except mean body weight, which was lower in Group A. The mean onset of sensory blockade was 8.45 minutes in Group A compared with 1.83 minutes in Group B, and the mean onset of motor blockade was 11.27 minutes versus 2.87 minutes, both p<0.0001. Complete sensory blockade was attained at 12.90 minutes in Group A versus 5.90 minutes in Group B, and complete motor blockade at 20.12 minutes versus 7.06 minutes, both p<0.0001. Duration of sensory blockade was 883.17 minutes (SD 66.27) in Group A versus 404.00 minutes (SD 95.85) in Group B, and duration of motor blockade was 819.07 minutes versus 380.38 minutes, both p<0.0001. Postoperative analgesia lasted 977.79 minutes (SD 66.90) in Group A compared with 492.66 minutes (SD 106.14) in Group B, p<0.0001. Complete motor blockade was achieved in 24 patients (80%) in Group A versus 16 patients (53.33%) in Group B, p=0.0285. Systolic blood pressure was significantly higher in Group B from five minutes onward, while diastolic pressure was consistently higher in Group A. No hypotension, bradycardia, or respiratory depression was recorded in either group. Conclusion Dexmedetomidine, when added to 0.75% ropivacaine for ultrasound-guided infraclavicular brachial plexus block, was associated with a significantly longer duration of sensory and motor blockade and postoperative analgesia, along with denser motor blockade, compared with fentanyl, despite a slower onset. Fentanyl was associated with a faster onset of blockade. Both adjuvants demonstrated a favorable safety profile, favoring dexmedetomidine when prolonged analgesia is clinically prioritized.