Jerusalem College of Engineering, Tamil Nadu, India

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1 Volume 119 No , ISSN: (on-line version) url: ijpam.eu NEUROMUSCULAR ELECTRICAL STIMULATION FOR DEEP VEIN THROMBOSIS THROUGH PPG SCREENING USING LABVIEW Purnima. S 1 and Ganga sri. V 2 1 Assistant Professor, 2 Student, Department of Biomedical Engineering, Jerusalem College of Engineering, Tamil Nadu, India purni_41@rediffmail.com Abstract - Neuromuscular Electrical Stimulation (NMES) uses an electrical current to cause a single muscle or a group of muscles to contract. Along with increasing the muscle function, the contraction of the muscle also promotes blood flow to the area, which assists in healing. Electrical stimulation has been used to facilitate upper and lower extremity mobility, muscle atrophy, Deep vein thrombosis (DVT) and many other complications. This paper describes the use of electrical stimulation for DVT condition. Deep vein thrombosis is the formation of blood clot within a deep vein in the body caused due to prolonged bed rest in cases of orthopedic surgery. Mostly DVT occurs in the lower leg or thigh. The main cause of DVT is poor blood flow. When flow slows, blood can pool, which gives the cells a chance to stick together and start clotting. People whose blood clotting rate is higher are at increased risk. Pulmonary embolism is a potential life threatening complication caused by the detachment of a clot that may travel to the lungs and may lead to mortality. Electrical foot stimulation has the potential to be an effective method of deep venous thrombosis prophylaxis. Short term electrical foot stimulation is at least as effective in increasing popliteal and femoral blood flow velocity. This paper discuss about the development of a circuit which reduces the severity of DVT by applying NMES. Keywords : Deep Vein Thrombosis (DVT), Neuromuscular stimulation (NMES), Photoplethysmography (PPG), Lab VIEW I. INTODUCTION A. Deep Vein Thrombosis (DVT) : Deep Vein thrombosis (DVT) is a condition in which large blood clots form in major veins within the muscles of the body, usually in the legs. If thrombi break loose from vessel walls, they can travel upstream and eventually obstruct the pulmonary artery creating a potentially fatal situation. A large deep vein thrombus can damage blood vessel valves, leading to lasting venous insufficiency, and could represent the genesis of chronic swelling pain. The development of venous thrombosis is best understood as the activation of clotting factors in areas of reduced blood flow (Stasis). Among those at high risk for DVT are the elderly, smokers, the obese, people with a history of vascular disease, pregnant woman, those who have sustained venous trauma (perhaps through limb injury), people who are paralyzed or temporarily immobilized (Post operative patients). B. DVT : Causes, Symptoms and treatment methods - (i) Causes : DVT occurs most commonly in people who are over 50 years by age. In certain following conditions where any alterations occurring in the blood flow through veins resulting in risk of developing clots having an injury that damages the vein, being overweight which puts on more pressure 15647

2 on the veins in legs and pelvis, having a family history of DVT, having a catheter placed in a vein, undergoing hormone therapy, heavy smoking habits. Some disease conditions like cancer, inflammatory bowel disease, hereditary blood clotting disorders also increase the risk of developing blood clot. II. METHODOLOGY AND TOOLS This paper describes the designing of a electrical stimulator unit whose activation is based on predictive value obtained through PPG acquired using LabVIEW which provides screening for DVT. The various phases of work done are acquisition of PPG, analysis and parameter calculation (DC & AC estimates and pulse rate), design of electrical stimulator circuit and its activation by threshold trigger. The following is the flowchart of the work. A. Flowchart of work : Fig. 1. Normal and DVT blood flow (ii) Signs and symptoms : Common symptoms and signs of DVT includes swelling in foot, ankle or leg, cramping pain in the affected leg, area of skin that is felt warmer than the surrounding areas, skin over affected area turning pale, dizziness, excessive sweating, chest pain that gets worse with coughing or inhaling deeply. (iii) Treatment Procedures : (i) Use of Anticoagulants / blood thinners (ii) Use of compression stockings (iii) Limb exercises (iv) Use of electrical stimulation C. Neuromuscular Electrical Stimulation (NMES) : Electrical stimulation is one of the best and most effective modalities used in physical therapy. A wide variety of electrical stimulators has a single common purpose the stimulation of tissue for therapeutic purposes. Electrical stimulation-induced contractions are used to activate the skeletal muscle pump, promote limb blood flow, and may be effective for reducing venous pooling / stasis. Therefore, electrical stimulation may reduce the incidence of deep venous thrombosis (DVT). NMES is a non-invasive, non-addictive means of muscle rehabilitation after injury, surgery or disease. Patients with a wide range of orthopedic and neurologic diagnoses can benefit from NMES, which applies customized electrical stimulus to cause a muscle to contract. The major benefit of integrating NMES in the treatment of patients is the reduction of total rehabilitation time and concomitant reduction in the total cost of recovery. The DVT is generally screened using ultrasound and PPG.The PPG sensor is placed in toe of the subjects and the signal is acquired using DAC in VI. The acquired signal is analyzed and the AC & DC values are estimated which are set as threshold for triggering an input. Another estimate is the pulse rate. When both the thresholds are attained for any acquired signal, trigger pulse for stimulus delivery is given. B. PPG Acquisition & Analysis : DVT patients have poor blood flow circulation. So, blood flow parameter is taken as a feedback from the patients which is sensed by PPG sensor. The PPG sensor is placed in toe of the subject and the signal is acquired in VI by using DAQ assistant as input device in LabVIEW. The signal is read in VI through Read From measurement file. The AC and DC component of the signal is determined by the AC&DC estimator

3 amplitude of the 2V is boost up to 5V by means of multiplier to give enough trigger voltage to stimulator. Fig. 2. Acquired PPG signal through LabVIEW The acquired PPG is analysed using DAQ Assistant. From the DC value the high voltage level is set as threshold as one of the triggering input. To calculate the pulse rate, the DC component of the signal is eliminated by using suitable Band Pass filter. Then the filtered signal is given as input to the peak detector. Then the number of peaks per minute is calculated and the heart rate is found. DVT patients have heart rate > 100 bpm. So the increased heart rate is set as another threshold to trigger. If both the thresholds occur then voltage of 5V is given as trigger input to the stimulator circuit using the DAQ assistant. From the PPG output, threshold for the trigger control set in the LabVIEW. The trigger is taken out from VI through DAQ and then given to the stimulator circuit. The output of the stimulator circuit(stimulus) is given to patient by means of electrode. Fig. 5. VI created in LabVIEW : III. RESULTS & CONCLUSION The PPG signals were acquired from different subjects using DAQ assistant and then analyzed using the VI created. The observation of AC and DC value was made and pulse rate was calculated for each subjects.the average of DC value was found and used as threshold to set the trigger condition. The following figure shows the front panel display of PPG acquired in LabVIEW. The stimulator is connected to the DSO and the spike output waveform was obtained from the designed stimulator circuit and the stimulus pulse was given to the calf muscle of the subject with DVT. Fig. 3. Acivation and delivery of stimulus Photoelectric Plethysmography relates the amount of vascular blood flow to the amount of light reflected. In DVT patients, the blood flow is minimum. Reduction of the amount of blood gives an increase in the intensity of the detected light. More the light reflected,greater the voltage. So the high PPG voltage used as a trigger to the stimulator. C. Trigger control : PPG is acquired through DAQ, using LabVIEW. To find the voltage from the PPG signal, AMPLITUDE AND LEVEL MEASUREMENTS is used. The comparison function GREATER THAN OR EQUAL TO is used for finding the voltage(2v) that relates the low blood flow. That gives the output whenever the signal reaches 2V. The Fig. 4. Stimulus signal It would appear from evidence presented in this paper that it is easy to acquire and analyse PPG for diagnosis and confirmation of DVT without risk to the subject under study. LabVIEW, the graphical programming software used is user friendly, easy to program and equipped with latest signal processing and analyzing tools. Provision for adjusting the parameters of the stimulus was also provided in the designed circuit. IV. REFERENCES [1] Masahiro Ojima, Ryosuke Takegawa et.al., Hemodynamic effects of electrical muscle stimulation in the prophylaxis of deep vein thrombosis for intensive care unit patients:a randomized trial, Journal of Intensive Care, Jan,

4 [2] Ravikumar R, Williams KJ, Babber A, Lane TRA, Moore HM, Davies AH et al., 2017, Randomised Controlled Trial: Potential Benefit of a Footplate Neuromuscular Electrical Stimulation Device in Patients with Chronic Venous Disease, EUROPEAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY, Vol: 53, Pages: , ISSN: [3] Ashima Sahoo, G.S.Rath,2012, Real Time Estimation of various physiological parameters by analysis of PPG signal., International Journal of Computer Applications, volume 57- No.15. [4] Brenda M.King,MedSci,2004, Using Photoplethysmography to assess for venous insuffieciency and screen for deep vein thrombosis (DVT) A review of the literature on the use of PPG as an assessment tool to identify the presence of venous insufficiency and in screening for DVT. [5] BJ Brodrick, 2013, Haemodynamic performance of neuromuscular electrical stimulation (NMES) during total hip arthroplasty. [6] Faghri P.D., Van Meerdervort H.F, Glaser R.M and Figoni S.F,1997, Electrical Stimulation and Deep Vein Thrombosis., IEEE Trans. Rehabilitation Engg.,p [7] George J.Dennis, 1998, Neuromuscular Electrical Stimulator for Deep Vein Thrombosis Treatment. [8] M.Ikeuchia, T.Mitani, S.Taniguchi, T.Tania, 2010, Prevention of Venous stasis in the Lower limb by Transcutaneous electrical nerve stimulation. [9] Incheol Jeong, Sukhwan Jun, Daeja Um, and Hyungro Yoon, 2009, Non- invasive Estimation of Systolic Blood pressure and Dialostic Blood Pressure Using Photoplethysmograph Components, Yonsei Med Journal, 51(3),p [10] M.Jothi Kumar, 2Chitravalavan IMPLEMENTATION OF BLAKE ALGORITHM USING PIPELINING IN FPGA International Journal of Innovations in Scientific and Engineering Research (IJISER) 15650

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