|Abstract:||Introduction: Diabetes Mellitus can lead to multiple complications including pathological changes in the vascular system. The hemodynamic changes of cutaneous microcirculation and small vein play an important role in pathogenesis and healing of peripheral tissues among people with diabetes. Reduction in blood flow (i.e. hypoperfusion) of peripheral circulation can be a factor contributing to foot ulcer. Chronic diabetic patients who suffer from prolonged hyperglycaemia are more likely to develop diabetic complications, which may subsequently lead to damage of tissues or organs. Very few studies have examined whether patients with different diabetic histories would influence the hemodynamics of peripheral blood vessels. Some studies have been done in studying retina or the kidney, but no study has examined the effects of diabetic history on resting hemodynamics of peripheral blood vessels in people with diabetes as compared with healthy control subjects. In terms of clinical management, electromagnetic field has been accepted as a non-pharmacological treatment that increases peripheral blood circulation in managing various clinical conditions. However, very few studies have examined the influence of pulsed electromagnetic fields (PEMF) on hemodynamics of peripheral blood vessels in people with diabetes. Some preliminary studies have shown that PEMF can increase peripheral circulation in people with diabetes, but due to limited technological skills, no previous study has attempted to make direct measurements of blood flow velocity in small vein in foot. In the present thesis, it consisted of two main studies that aimed to: (1) compare the blood flow velocity of superficial small veins and blood flow (in terms of flux) of the cutaneous microcirculation in the dorsal foot, between subjects with long history or short history of diabetes as compared to healthy control subjects; (2) compare the effects of active PEMF and sham PEMF on blood flow velocity and diameter of the superficial small veins; and the blood flow (flux) of the cutaneous microcirculation in the dorsal aspect of foot for subjects with diabetes and healthy control subjects respectively.|
Methodology and Results: Study 1: Examination of the hemodynamics of the peripheral blood vessels in people with diabetes. A total of 70 subjects were recruited and classified into three groups: 38 healthy control subjects, 16 subjects with diabetic history of below or equal to 10 years, and 16 subjects with diabetic history above ten years. Three outcome measures were recorded, including the blood flow velocity of the smallest observable superficial small veins in the skin over the base of 1st metatarsal bone, measured by ultrasound biomicroscopy; and the blood flow (Flux) of microcirculation measured in skin over the base of 1st metatarsal bone (Flux1) and the distal 1st phalanges bone (Flux2) by laser Doppler flowmetry. The present study found no significant differences in all three outcomes between the three groups (all P > 0.05). However, the results showed that the blood flow velocity of small blood veins, Flux1 and Flux 2 in the subjects with a long history of diabetes tends to be lowered than that of the healthy control subjects. No obvious difference was found between the subjects with a short diabetic history and the healthy control group. Study 2: The influence of pulsed electromagnetic fields on the hemodynamics of the peripheral blood vessels in people with diabetes and healthy control subjects. A total of 43 subjects participated in this study. They were classified into subjects with diabetes and healthy control subjects, then each type of subjects were randomly allocated to receive either active PEMF or sham PEMF. Four outcome measures were recorded immediate before and after 30 minutes of PEMF therapy, including the blood flow velocity and diameter of the smallest observable superficial veins in the skin over the base of 1st metatarsal bone as measured by ultrasound biomicroscopy; and the blood flow (flux) of microcirculation in the skin over the base of 1st metatarsal bone (Flux1) and the distal 1st phalanges' bone (Flux2) measured by laser Doppler flowmetry. The changes in the four outcomes recorded before and after PEMF therapy were computed and compared between the active and sham group for the diabetic and healthy control subjects respectively. In both types of subjects (diabetic and healthy control subjects), the changes in blood flow velocity of the smallest observable superficial small veins in the active PEMF group were significantly greater than that in the sham group (between-group P < 0.05). However, the changes in the diameter of the small blood veins, Flux1 and Flux2 showed no significant difference between the active and sham PEMF groups for both types of subjects (all P > 0.05). Conclusions: We found no significant differences in the blood flow velocity of small blood veins, or the blood flow (flux) of cutaneous microcirculation measured in the dorsal foot between the three groups. However, the group with a long history of diabetes tended to have reduced hemodynamic responses in all three variables, as compared to the healthy control group. In addition, our findings suggest that PEMF is a potential intervention for diabetic patients, which can improve vascular disturbance of the foot by increasing the blood flow velocity on the superficial small veins rather than microcirculation. Future study with larger sample size is recommended to confirm our findings.