Human thermal response with improved AVA modeling of the digits

The arterio-venous anastomoses (AVA) play a major role in the blood circulation in the peripheral body parts. In this work, the segmental bioheat model of Salloum et al. [1] is improved to accurately predict skin blood flow rate in the hands and fingers, and the local and overall human thermal responses in transient environments. The improvements in the model include: 1) extending the artery tree to include the arterial branching to the five fingers; 2) modeling and distribution of the blood flow between the deep and superficial veins in the peripherals; 3) adjusting arteries' radii during dilation and constriction; 4) innovative modeling of AVA of the fingers. The model focus is on the accurate blood flow calculation to the different body segments proposing a better blood control mechanism through relating the arterial tree radii as well as the AVA control mechanism to cardiac output. The skin blood flow and digits' dynamic thermal response predicted by the model were compared with published experimental values on body core and skin temperatures and local skin temperatures of fingers. Good agreement was obtained with experimentally reported values on average skin, core, and finger skin temperature response of subjects exposed to gradual decrease in air temperature from 32.3 °C to 13 °C. The new integrated AVA model of the fingers with the bioheat model is capable of predicting digits' dynamics thermal response with better accuracy than some previous models while also incorporating the complex central and local thermoregulatory functions.

► A new AVA blood flow control model is developed for the fingers. ► The arterial tree radii and AVA control mechanism are related to cardiac output. ► The integrated finger AVA and bioheat models predict fingers' thermal response. ► Predicted segmental skin temperature agreed well with published experimental data. ► The finger temperature is accurately predicted during cold exposure transients.