Original article / research
Role of Perfusion Index as an Early Predictor of Successful Ultrasound-guided Supraclavicular Brachial Plexus Block: A Prospective Observational Study
UC15-UC19
Correspondence
Dr. Gedela Sai Sravani,
Junior Resident, Department of Anaesthesiology, Krishna Vishwa Vidyapeeth (Deemed to be University), Karad-415539, Maharashtra, India.
E-mail: sravanianaesthesia@gmail.com
Introduction: Supraclavicular brachial plexus block is commonly used for upper limb surgeries, providing effective anaesthesia and postoperative analgesia. Sensory and motor assessment is subjective and may delay decisions. Perfusion Index (PI) may provide an early objective indicator of sympathetic blockade and block success.
Aim: To evaluate pulse oximetry-derived PI as an early objective predictor of successful ultrasound-guided supraclavicular brachial plexus block and to compare it with routine clinical assessment.
Materials and Methods: This was a hospital-based prospective observational study conducted in the Department of Anaesthesiology, Krishna Hospital and Medical Research Centre, Krishna Institute of Medical Sciences, Krishna Vishwa Vidyapeeth, Karad, Maharashtra, India, over 18 months from June 2024 to November 2025. It included 70 adults aged 18-60 years with American Society of Anaesthesiologists (ASA) physical status I or II who underwent upper limb surgery under ultrasound-guided supraclavicular brachial plexus block. PI was measured in the blocked and contralateral limbs at baseline, 10 minutes and 20 minutes after block administration. The PI ratio was calculated by dividing the PI value at 10 minutes after block administration by the baseline PI value. Standard sensory and motor testing was used to assess block success. Independent t-test, Pearson’s correlation, and receiver operating characteristic analysis were used.
Results: A total of 70 patients were included in the final analysis. The mean age was 45.2±5.4 years, mean weight was 70.0±3.3 kg, mean height was 166.3±3.5 cm, and mean body mass index was 25.3±0.3 kg/m². Successful surgical block was achieved in 54 patients (77.1%), while 16 patients (22.9%) had failed/inadequate block requiring fentanyl supplementation. Among successful blocks, mean sensory onset time was 12.4±0.5 minutes and mean motor onset time was 15.8±0.5 minutes. Baseline PI was comparable between successful and failed/inadequate blocks (1.39±0.07 versus 1.41±0.06; p=0.121). PI at 10 minutes, PI at 20 minutes and the 10-minute PI ratio were significantly higher in successful blocks than in failed/inadequate blocks (p<0.001). The 10-minute PI ratio showed a significant negative correlation with sensory and motor onset times (r=-0.71 and r=-0.70, respectively; p<0.001). ROC analysis demonstrated excellent discriminatory performance within the present dataset. However, the observed estimates should be interpreted cautiously because they were derived from a single-centre observational cohort and require external validation.
Conclusion: PI is a simple, non invasive, and reliable adjunct for early prediction of supraclavicular block success. PI demonstrated excellent diagnostic performance and may serve as an objective adjunct to routine sensory and motor assessment.