Comparison of a hand-held high-end resolution infrared thermography (FLIR P640) and a smartphone infrared thermographic device (FLIR One) for the assessment of skin surface temperature after anaesthetising the median nerve in Healthy horses.
Authors: Ferlini Agne Gustavo, Adamson Kellie, McGlinchey Leah, Kravchuk Olena, Santos Luiz, Schumacher John
Journal: PloS one
Summary
# Editorial Summary Assessing the efficacy of regional nerve blocks in equine practice typically relies on subjective tests of skin sensitivity, but infrared thermography offers a potentially objective alternative by detecting temperature changes in anaesthetised dermatomes. Researchers compared two thermographic cameras—a professional-grade FLIR P640 and a smartphone-based FLIR One device—to evaluate skin surface temperature changes following median nerve blocks in healthy horses, with images captured at baseline and 30, 60, and 90 minutes post-anaesthesia using 2% mepivacaine hydrochloride. The P640 achieved >50% agreement amongst assessors for detecting nerve block presence based on thermal changes within the median nerve dermatome, with objective analysis revealing significant temperature increases in treated legs at the medial fetlock and lateral pastern by 60–90 minutes. The FLIR One, whilst detecting some temperature changes in treated legs at similar timepoints, also produced unexplained temperature increases in non-treated contralateral limbs and demonstrated systematically higher readings with a wider temperature range than the P640, raising concerns about reliability and specificity. Whilst infrared thermography shows genuine promise as an objective tool for confirming proximal nerve blocks in equine regional anaesthesia protocols, practitioners should restrict use to high-resolution professional cameras rather than smartphone devices; further research with larger cohorts and alternative nerve blocks is needed to establish thermography as a standard assessment method in clinical practice.
Read the full abstract on PubMed
Practical Takeaways
- •Infrared thermography with high-end equipment (FLIR P640) can objectively confirm median nerve block success by detecting predictable skin temperature increases in the nerve's dermatome
- •Smartphone-based IR thermography devices are unreliable for nerve block assessment due to poor specificity and should not be used clinically for this purpose
- •Practitioners using IR thermography for regional anaesthesia validation should invest in professional-grade cameras and be aware that skin temperature interpretation requires careful technique and controlled conditions
Key Findings
- •High-end FLIR P640 thermography showed >50% assessor agreement for detecting median nerve block presence via dermatome skin temperature changes
- •FLIR P640 detected significant skin temperature increases at medial fetlock (60 min) and lateral pastern (90 min) post-block
- •FLIR One smartphone device showed poor specificity, detecting temperature increases in both treated and non-treated legs and is unsuitable for nerve block assessment
- •P640 camera provided superior resolution and thermal detail compared to FLIR One, though One showed wider temperature range