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FM220 Intermittent Compression System

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FM220 Proof Points

Proof Points from Literature on Need for FM220

1. PAD is a progressive disease, and if left untreated, greatly affects quality of life.

Peripheral Arterial Disease (PAD) is a distinct atherothrombotic syndrome marked by stenosis and occlusion of peripheral arterial beds, typically in the lower extremities; it can be symptomatic or asymptomatic. Depending on the degree of vascular obstruction, the symptoms of PAD can range from exercise-associated pain to impaired wound healing that may necessitate limb amputation. The most common cause of peripheral arterial disease is the buildup of atheromatous plaque in the major vessels to the lower extremities. Arterial occlusions decrease the arterial lumen through which oxygen and nutrient rich blood can flow. Diminished arterial blood flow produces a supply-demand mismatch during exercise and the resultant symptom of claudication [1].

Intermittent Claudication (IC) is characterized by pain that develops during exercise and is relieved by rest, is the most common symptom of PAD. Since PAD is a progressive disease, patients usually experience a slow deterioration in quality of life as their walking ability gradually declines [1], [2] .

As the disease progresses, the patient might suffer from rest pain and/or ischemic ulceration, which are the result of Critical Limb Ischemia (CLI), the most serious complication of the disease [3], [4] . These non healing ulcers can lead to amputation, disability, pain and even death[5] . However, studies of large patient groups with intermittent claudication have demonstrated that amputation is uncommon. Less than 4% of patients with claudication will progress to critical limb ischemia, which are ischemic rest pain, ulceration, tissue necrosis and gangrene [1]. Importantly, PAD is a marker for generalized atherosclerosis and is closely associated with coronary and cerebrovascular disease and the severity of PAD has been correlated with an increased risk of myocardial infarction, stroke, and cardiovascular death [1], [4],[6] . Regardless of whether symptoms are evident, patients with PAD are six times more likely to die within ten years than patients without PAD [7] .

2. Current Treatment of PAD

Early diagnosis and intervention is the most important factor in the treatment of PAD. Current treatments include:

  • Lifestyle changes (risk-factor modification), including smoking cessation, control of diabetes, and blood pressure and lipid normalization,
  • Exercise training
  • Pharmacologic therapy.
    Two FDA approved drugs, Pentoxifylline (Trental) and Cilostazol (Pletal), are widely used in the United States for reducing PAD symptoms. Although both are approved for the treatment of IC, only the latter has been shown to be significantly effective in increasing the walking distance in IC patients [1].
  • Surgically, by revascularization or, in extreme cases, by amputation [1].
  • Pneumatic Compression Devices

3. Role of Pneumatic Compression Devices in Treatment of PAD

Lower limb hemodynamics and the effects of intermittent compression on the lower limb have led to an increasing awareness of the potential therapeutic value of intermittent compression in both venous and arterial diseases. Intermittent Pneumatic Compression (IPC), a process of alternating high and low pressures on the limbs, is a well-known method, principally used for the prevention of Deep Vein Thrombosis (DVT) and reduction of Lymphedema in the lower limbs. In the last two decades, however, the concept of using IPC for the treatment of ischemic legs reemerged [8] . This method, which applies impulse compression based on high pressure rapid inflation technology, was found to improve arterial circulation in the lower limbs [9] and thus is a relevant treatment for PAD [10] .

5 years ago, intermittent pneumatic compression (IPC) of the foot was found to significantly improve the walking ability of patients with stable intermittent arterial claudication [11] .Although it is still unclear how IPC actually exerts its beneficial effects and its exact physiological mechanisms of action are unknown, various studies have demonstrated conclusive physiological benefits to IPC management as well as improvement in PAD symptoms. Indeed, it was shown that in addition to improvement in lower extremity arterial flow, IPC management improves walking ability, relieves rest pain and limits tissue damage[10], [12], [13], [14], [15] , all may result in improving the quality of life of patients with PAD.

Indirect benefits for this kind of treatment include low cost of treatment, ease of outpatient care and avoidance of costly and dangerous invasive procedures. It has been suggested that the state of enhanced leg inflow accrued during the application of IPC may promote arterial collateralization, attenuating the increased fixed component of peripheral resistance due to atherosclerotic occlusion of the main axial arterial lumens[14].

4.  Feasibility Study, Horev Center, Israel

    This feasibility trial was designed at the early development stages in order to evaluate and determine the optimal number of pulses per minute required for increasing blood flow and improving perfusion parameters while an intermittent mechanical compression device prototype is positioned on the calf. The device was set to generate a pressure level of ~65 mmHg. All measurements were taken with the device operating at 3 and 6 pressure pulses/min.

    This trial was presented as a poster at the 3rd Mayo clinic vascular symposium in September 2004 and was awarded for the best poster in clinical research of vascular disease.

    Ten patients with known peripheral arterial disease suffering from intermittent claudication were enrolled to the study, after giving their signed informed consent. Measurements were taken before, during and up to one hour after operating the device on the symptomatic leg. Measurements taken on the other leg served as the control. All experiments were conducted in a seated position.

    Results of Study

    • The mean flow volume (FV) in the superficial femoral vein increased by 37% from 66 to 90 ml/min, at 3 pulses/min. This result was close to be statistically significant (P=0.07). At 6 pulses/min the flow decreased by 32%.
    • Peak systolic velocity increased by 10% with device operation at both pulse rates. At 3 pulses/min (P=0.026) and at 6 pulses/min (P=0.08).
    • There was no significant change in pulsatility index (PI), although we observed an increase in diastolic velocity throughout the whole diastole, which might suggest reduction in peripheral resistance.
    • Mean arterial volume flow increased from 89 to 150 ml/min with the device set at 3 pulses/min – a 68% increase (P=0.02), and remained elevated at 6 pulses/min (142ml/min; P=0.005 ). When device operation was stopped, the flow returned back to baseline levels after several minutes.
    • Tissue blood flow, as measured by tissue Doppler flowmetry, increased significantly from 2.57 to 2.98 ml/min/100 g tissue, with the device set at 3 pulses/min (P=0.015), and further increased to 3.22 ml/min/100 g tissue at 6 pulses/min (P=0.0015).
    • Mean tissue oxygen pressure (TcpO2), increased from 57.9 to 62.5 mmHg (8%, P=0.014) at 3 pulses/min, and further increased to 67.4 mmHg at 6 pulses/min (17%, P=0.005).
    • ABI did not change, and mean values were 0.7 and 0.87 in the symptomatic and the control leg respectively (seated position). Nevertheless, TBI values increased significantly from 0.52 to 0.58 (P=0.044) at 3 pulses/min, remained as high as 0.56 at 6 pulses/min (P=0.044), and continued to increase up to 0.60 even after device operation was stopped.

    Conclusion

    The new mechanical compression device when operated at ~65 mmHg, 3 pulses/min, augments arterial blood inflow and perfusion parameters in patients with PAD. Theses results are similar to those that were previously reported with IPC devices. In addition, this portable easy to use device should increase patient compliance.
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    [1] Bradberry JC. Peripheral arterial disease: pathophysiology, risk factors, and role of antithrombotic therapy J Am Pharm Assoc (Wash DC). 2004 Mar-Apr;44(2 Suppl 1):S37-44; quiz S44-5

    [2] Schainfeld RM. Management of peripheral arterial disease and intermittent claudication. J Am Board Fam Pract. 2001 Nov-Dec;14(6):443-50

    [3] Palmer-Kazen U, Wahlberg E. Arteriogenesis in peripheral arterial disease. Endothelium. 2003;10(4-5):225-32

    [4] Aronow WS. Management of peripheral arterial disease of the lower extremities in elderly patients. J Gerontol A Biol Sci Med Sci. 2004 Feb;59(2):172-7

    [5] Montori VM, Kavros SJ, Walsh EE, Rooke TW. Intermittent compression pump for non-healing wounds in patients with limb ischemia. The Mayo Clinic experience (1998-2000). Int Angiol. 2002 Dec;21(4):360-6

    [6] Dawson DL, Hiatt WR, Creager MA, Hirsch AT.   Peripheral arterial disease: medical care and prevention of complications. Prev Cardiol. 2002 Summer;5(3):119-30

    [7] Priollet P. Quality of life and peripheral arterial disease: perspectives for the future. Drugs 1998; 56 (suppl. 3): 49-58

    [8] Banga JD, Idzerda HHD, Schuurman JG, Eikelboom BC. Intermittent pneumatic compression therapy in patients with leg ischemia. Int Angiol 1995;3:202)

    [9] Eze AR , Comerota AJ, Cisek PL, et al. Intermittent calf and foot compression increases lower extremity blood flow. Am J Surg 1996;172:130-5

    [10] Labropoulos, C. Wierks, B. Suffoletto.   Intermittent pneumatic compression for the treatment of lower extremity arterial disease: a systematic review.   Vascular Medicine 2002; 7:141-148

    [11] Delis KT, Nicolaides AN. Effect of intermittent pneumatic compression. Ann Surg 2005 Mar; 241(3): 431-41

    [12] Delis K.T., Nicolaides, N. Wolfe J.H.N. and Mchir G.S. Improving walking ability and ankle brachial pressure indices in symptomatic peripheral vascular disease with intermittent pneumatic foot compression: A prospective controlled study with one year follow-up. Journal of Vascular Surgery, April 2000; 31(4): 650-661

    [13] K.T. Delis, M.J. Husmann, G. Szendro, N.S. Peters, J.H.N. Wolfe and A.O. Mansfield. Heamodynamic effect of intermittent pneumatic compression of the leg after infrainfuinal arterial bypass grafting.   British Journal of Surgery 2004; 91:429-434

    [14] Kumar S, Walker MA. The effects of intermittent pneumatic compression on the arterial and venous system of the lower limb: a review. J Tissue Viability. 2002 Apr;12(2):58-60, 62-6

    [15] Chen AH, Frangos SG, Kilaru S, Sumpio BE.Intermittent pneumatic compression devices - physiological mechanisms of action. Eur J Vasc Endovasc Surg. 2001 May;21(5):383-92

    		 
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