A blood clot forming in one of the deep-running veins in our body can have serious consequences, even sometimes leading to pulmonary embolism. For the relief of those who are prone to deep vein thrombosis, such as patients needing to stay in bed for longer than 24 hours, hospitals use the external pneumatic compression device also known informally as the deep vein thrombosis pump. The device is usually imported for a huge sum. Now, researchers from Thiruvananthapuram have indigenously developed this device at a much lower cost than the imported ones.
Blood circulation from the lower parts of the body back to the heart is maintained by the pressure exerted on the deeper veins by the muscles. If this process is interrupted, clots can form in the deep veins, which can travel upwards and reach the heart or lungs and cause serious problems.
“The normal movement given by the muscles to keep the blood flowing is replicated by the device,” says Jithin Krishnan, a scientist and engineer with the Department of Medical Devices Engineering at Sri Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram. The device is attached to a disposable sleeve which is wrapped around the legs from feet to thigh. The sleeve has bladders into which air is pumped sequentially, imitating the muscle action. This needs care, firstly the arteries that run along to top layers should not get ruptured, and secondly, the process should not be too fast. This is needed to avoid damage to the nerves and valves in the veins also.
Mr Krishnan, who is the principal investigator of the work, explains: “Once you compress a section of the veins, the blood from there flows up to the next section where it is held from flowing back by the valves. The pressed section now has to relax and blood should refill it. An appropriate relaxation time has to be given. All this is built into the device.” Along with that some residual pressure is built in to improve blood circulation.
Other technical features include software that adjusts the amount of pressure. This can range from 10 mm to 130 mm of mercury. The pressure is adjusted so that the patient does not feel discomfort and also for correct venous refilling etc. The device can function in six modes such as feet-only mode, calf-only mode, thigh-only mode etc. Combinations of these modes can also be set. Also, alarms can be set to alert the doctor if the pressure exceeds optimum.
The imported device costs around ₹1-2 lakh. “We wanted to enter the market with a low-cost product that would have all the sophistication and clinical viability of an imported device,” Mr. Krishnan says. “We wanted to come up with a device that every hospital can afford.”
The product will be manufactured by Enproducts in Kochi.