Early Detection of Supraclavicular Brachial Plexus Block Failure Using Infrared Thermography and Perfusion Index

Overview

Successful peripheral nerve blockade is fundamental to modern regional anesthesia, particularly for upper limb surgeries. Ensuring the efficacy of a nerve block early in the perioperative period is critical, as delayed recognition of block failure may lead to intraoperative pain, the need for additional sedation or general anesthesia, and overall poorer patient outcomes. Conventional methods for assessing block success, such as sensory testing with pinprick or cold stimuli and motor assessment using strength scales, require patient cooperation and often take 15-30 minutes to yield definitive results. These delays are especially limiting in fast-paced surgical environments or when early decisions regarding anesthesia management are necessary. Emerging non-invasive monitoring technologies offer promising alternatives for the early, objective assessment of block efficacy. Infrared Thermography (IRT) measures skin surface temperature, which increases due to sympathetic nerve blockade-induced vasodilation.

Successful peripheral nerve blockade is fundamental to modern regional anesthesia, particularly for upper limb surgeries. Ensuring the efficacy of a nerve block early in the perioperative period is critical, as delayed recognition of block failure may lead to intraoperative pain, the need for additional sedation or general anesthesia, and overall poorer patient outcomes. Conventional methods for assessing block success, such as sensory testing with pinprick or cold stimuli and motor assessment using strength scales, require patient cooperation and often take 15-30 minutes to yield definitive results. These delays are especially limiting in fast-paced surgical environments or when early decisions regarding anesthesia management are necessary. Emerging non-invasive monitoring technologies offer promising alternatives for early, objective assessment of block efficacy. Infrared Thermography (IRT) measures skin surface temperature, which increases with sympathetic nerve blockade-induced vasodilation. Perfusion Index (PI), derived from pulse oximetry, reflects peripheral perfusion and also rises as vascular tone decreases following a successful nerve block. Both IRT and PI provide quantifiable, real-time physiological markers of sympathetic and circulatory changes that precede full sensory or motor blockade. Although several studies support their individual utility, there is limited evidence on their combined predictive value or their integration into routine clinical practice. Further investigation is needed to validate their role in enhancing the accuracy and timeliness of block assessment.