Infrared thermal imaging of human skin temperature during combined simulated hemorrhage and thermal stress

Abstract

Digital infrared thermographic imaging (DITI) may be useful as a remote diagnostic tool for assessment of hemorrhagic injury. Under normal ambient temperatures DITI tracks reductions in central blood volume during simulated hemorrhage from changes in forehead skin temperature. This study tested the hypotheses that (1) DITI can detect changes in forehead skin temperature during simulated hemorrhage under elevated ambient conditions, and (2) changes in skin temperature detected with DITI correlate with changes in skin temperature using thermocouples. Ten healthy subjects were instrumented for ECG, beat‐by‐beat arterial pressure (Finometer), forehead skin temperature (thermocouple and DITI) and rested in the supine position for 60 min in a heated chamber (40 °C). Data were collected during continuous lower body negative pressure (LBNP) until pre‐syncope. DITI tracked the progressive reduction in forehead skin temperature during LBNP (baseline 35.9 ± 0.3 °C vs. pre‐syncope 35.3 ± 0.3 °C, p = 0.001). Correlations between DITI and thermocouple measurements throughout the protocol were high (r2 = 0.88), and did not differ at baseline (p = 0.53) or during LBNP (p ≥ 0.20). These data suggest that DITI may be an appropriate surrogate for remote, or non‐contact assessment of skin temperature in elevated ambient conditions and may prove to be a useful tool in the development of future technology for remote triage.