Effect of hyperbaric oxygen on cardiac neural regulation in diabetic individuals with foot complications

Aims: There are relatively few effective methods to treat autonomic neuropathy in patients with diabetes mellitus. Our aim was to test the hypothesis that hyperbaric oxygen therapy may restore cardiac neural regulation dysfunction in diabetic individuals with foot complications. Methods: We conducted a prospective randomized controlled study in patients with diabetic foot problems. Daily heart-rate variability analysis from 5-min electrocardiography was used to evaluate the temporal change of cardiac neural regulation. The experimental group consisted of 23 subjects exposed to hyperbaric oxygen therapy of 202.65 kPa for 90 min every Monday to Friday for 4 weeks (20 treatments). The control group consisted of 15 age-, sex- and disease-matched subjects who were not exposed to hyperbaric therapy. Patients with medical complications and failure of wound healing were excluded to eliminate possible confounding effects. Results: There was no significant difference in baseline R-R interval (RR), variance, high-frequency power (HF), low-frequency power (LF), and LF/HF ratio between the two groups. In the hyperbaric oxygen group there were significant increases in changes of RR (82.7 ± 16.02 ms); variance 0.88 ± 0.12 ln(ms²); HF 1.06 ± 0.18 ln(ms²); and LF 0.87 ± 0.15 ln(ms²) after the treatment. Measurements of tissue oxygen demonstrated significant increases in local tissue oxygenation in the hyperbaric oxygen group (53.0 ± 2.6 mmHg) compared with the control group (27.5 ± 3.1 mmHg), P < 0.05. Conclusion: Hyperbaric oxygen therapy has a significant vagotonic effect, which is beneficial in improving cardiac neural regulation in patients with diabetic autonomic dysfunction.