Low-cost infrared cameras for assessing lumbar sympathetic blocks in complex regional pain syndrome: A preliminary study

The aim of this preliminary study was to evaluate the applicability of low-cost infrared thermography cameras for assessing lumbar sympathetic blocks (LSBs) in patients diagnosed with lower limb Complex Regional Pain Syndrome. Skin temperature was monitored in 7 patients (8 LSBs) over 220 s following the injection of a local anesthetic (10 ml of 0.25 % levobupivacaine together with 80 mg of triamcinolone) aimed at inducing vasodilation in the affected foot. Two infrared cameras, FLIR E60 (high-performance) and HIKMICRO Mini-X (low-cost), and a black body calibrator (BX-500 IR) were used. For both feet, mean, maximum, and corrected mean skin temperatures (adjusted using the black body) were recorded. Based on these, variations (relative to baseline) and temperature asymmetries were calculated. In most cases, effect sizes between camera measurements were negligible or small. However, moderate effect sizes were found in some mid-test variation parameters (e.g., ES = 0.7 for mean skin temperature variation). Reliability between cameras was acceptable for most parameters (ICC>0.40), and excellent for corrected mean temperature (ICC = 0.89) and asymmetry metrics (ICC>0.83). In conclusion, low-cost infrared thermography cameras may be suitable for evaluating LSB performance when focusing on skin temperature asymmetry, and the use of a black body reference to correct mean temperature measurements. • Two IRT cameras were compared: FLIR E60 and HIKMICRO Mini-X (low-cost). • Skin temperature asymmetry had the highest reliability of a low-cost IRT camera. • The use of a black body improves the mean value of a low-cost IRT camera.