Utility of thermography for assessing the success and spread of erector spine plane block in video assisted thoracoscopic surgery

Background – Objective assessment of the success and spread of interfascial plane blocks remains challenging. Infrared thermography may offer a non-invasive method to evaluate erector spinae plane block (ESPB) by detecting cutaneous temperature changes related to sympathetic blockade. 

Methods – In this prospective observational study, adult patients undergoing video-assisted thoracoscopic surgery were allocated to either general anesthesia alone or ESPB combined with general anesthesia. Infrared thermographic imaging was performed preoperatively and postoperatively. Intraoperative opioid consumption, postoperative pain scores, and time to first strong opioid requirement were recorded. 

Results – Thirty-one patients were analyzed. Intraoperative opioid consumption was significantly lower in the ESPB group (p < 0.001). Thermography demonstrated localized postoperative temperature changes (T6 and T7); however, these changes were modest in magnitude and did not demonstrate statistically significant between-group differences at individual dermatome levels. 

Conclusion – In the ESPB + GA group, infrared thermography detected increased postoperative temperatures localized in dermatomes T6 and T7, consistent with sympathetic effects related to the erector spinae plane block (ESPB) used in VATS; therefore, infrared thermography monitoring can be considered clinically relevant and it can be used to assess the metameric extent achieved by ESPB; in addition, the ESPB + GA group showed a reduction in the need for intraoperative opioids, better postoperative analgesia, and a later need for postoperative opioid rescue.