Thermal biofeedback and lower extremity blood flow in adults with diabetes: is neuropathy a limiting factor?

Thermal biofeedback may be a useful adjunctive technique for enhancing cutaneous blood flow in patients with lower-extremity vascular complications of diabetes. However, autonomic, sensory, and/or motor neuropathies may impair vasomotion and limit the ability to alter blood flow and achieve significant foot warming with thermal biofeedback. We examined nerve function associated with four common types of diabetic neuropathy (sympathetic-autonomic, vagal-autonomic, sensory, and motor), hypothesizing that both sympathetic-autonomic and sensory neuropathies would limit the acquisition of biofeedback-mediated foot warming. Twenty-four participants with diabetes mellitus (19 with type II and 5 with type I) received a nerve conduction study and neurological evaluation of the upper and lower extremities. Hand temperature, foot temperature, and electrodermal gradient at the toes were monitored across six thermal biofeedback sessions. Participants were able to significantly raise p < .01) foot temperatures across sessions, an average of 2.2 degrees F. Consistent with our hypotheses, 41% of the variance in foot warming was explained by lower-extremity sympathetic-autonomic and sensory nerve function tests. This study demonstrated that a general diabetic population, including patients with mild-to-moderate neuropathy, can increase skin perfusion with thermal biofeedback. As hypothesized, lower-extremity sympathetic-autonomic and sensory neuropathies interfered with foot warming.