Circulator Boot and Topical Oxygen Therapy
Patent #3,961,625, June 8, 1976: Number 10 labels the wall of the glass boot; 12, the opening for the insertion of the leg; 14, the rubber cuff to seal the boot to the leg; 16, the air or oxygen line from the wall outlet to the boot; 18, the rocker bar which rotated clockwise blocks gas flow into the boot and allows a large opening (22) to vent the boot; and 26, a pulse sensor on the proximal thigh to signal to the monitor that the pulse wave has arrived and that it is time to vent the boot. Either oxygen or compressed air was used to power the boot which had the main purpose of assisting blood flow throughout the leg. The hospital safety committee had reservations about fire hazards with the use of oxygen.
We discontinued the use of such boots and developed our heart monitors and other boots. The rubber seal at the opening of the boot had to be tight enough to contain whatever air pressure we introduced into the boot. This band of pressure decreased both arterial inflow and venous outflow. Adverse effects of capillary skin flow was not seen as the pressure was applied intermittently with each pulse wave. Constant pressure within such boots is another thing, however. Capillary flow requires 10 to 20 mm Hg pressure. Pushing on the skin can blanch it and decrease the blood flow to the skin especially in ischemia legs. Hyperbaric oxygen treatments, in which the whole body is immersed in gas under pressure, does not suffer from these problems. The hyperbaric chamber would push blood and fluid into the leg if it were to protrude from the pressurized chamber. What do we recommnend then? Use the bag technique described in our Methods section if topical oxygen therapy is indicated. One may choose to do oxygen therapy during boot treatments (placing the foot with its oxygen bag within the Circulator Boot), between boot treatments or both. Costs of topical O2 therapy are thus reduced and patient comfort is increased.