Pioneering Non-Invasive Vascular Technologies Since 1984
Header:

Compressing the foot and why it’s so important

Why calf-only arterial pumps are missing out

ArtAssist device compression sequence

ArtAssist®…The Arterial Assist Device® Compression Sequence

Calf-only arterial pumps are missing a key component because foot compression is essential to improving circulation in the skin of the foot. Good circulation is vital to the successful healing wounds and ulcers. ACI Medical’s ArtAssist® device went through numerous clinical trials in order to optimize compression therapy for treating peripheral arterial disease of the legs and feet.

Researchers and engineers optimizing the ArtAssist® device not only discovered the importance of compressing the foot in addition to the calf, but they also designed this arterial pump technology to imitate the physiological act of walking as closely as possible.

A bit of background

An early study to determine the physiological effects of  intermittent pneumatic compression therapy focused compression on the calf, foot, and both simultaneously.

Although significant increase in arterial blood flow was recorded for individual compression areas, the simultaneous combination yielded disappointing results because blood was not flowing back to the heart as anticipated.

After the conclusion was drawn that simultaneous compression did not produce the desired augmented blood flow for all tissues below the knee, researchers realized that the answer lay in a time delay. Strong, encompassing foot and ankle compression that boosts foot skin perfusion would come first, followed then by calf compression to amplify popliteal flow.

That magical formulation

In essence, foot/ankle compression + calf compression with time delay = successful emptying of venous blood, resulting in improved circulation.

The optimization study led by K. T. Delis, et. al. determined that this foot, ankle and calf compression sequence, applying 120-140 mmHg at a frequency of 3-4 impulses per minute, “provided the optimum intermittent pneumatic stimulus.”

The next logical step was a prospective randomized controlled trial to solidify the efficacy claims.

And the rest is history…

One example of such a trial studied not only the effects of the previously mentioned IPC method, but also the long-term effects on treated claudicants. The results indicated that treated claudicants still retained their ABI’s and walking benefits one year after the end of IPC application.

Following the numerous physiological and optimization studies for the ArtAssist® device, research facilities continued to explore the possibilities of arteriogenesis, therapy for patients with intermittent claudication, and limb salvage.

The ArtAssist® device is currently the only IPC device with this thorough progression of clinical studies and randomized controlled trials to support its efficacy.

References

  1. Improving Popliteal Artery Flow with Intermittent Pneumatic Foot and Calf Compression.” Delis, K.; Labropoulos, N.; Nicolaides, A.N.; Stansby, G.; and Lumley, J. Irvine Laboratory for Cardiovascular Investigation and Research, Academic Surgical Unit, Imperial College School of Medicine, St. Mary’s Hospital, London, UK.
  2. Enhancing Venous Outflow in the Lower Limb with Intermittent Pneumatic Compression. A Comparative Haemodynamic Analysis on the Effect of Foot vs. Calf vs. Foot and Calf Compression.” Delis, K.T.; Slimani, G.; Hafez, H.M. and Nicolaides, A.N. Irvine Lab for Cardiovascular Investigation and Research, Academic Vascular Unit, Imperial College School of Medicine, St. Mary’s Hospital, London UK. Eur J Vasc Endovasc Surg 19, 250-260; 2000
  3. The Acute Effects of Intermittent Pneumatic Foot and Calf Compression on Popliteal Artery Hemodynamics: A Comparative Study.” Delis, K.T.; Nicolaides, A.N.; Labropoulos, N.; and Stansby, G. Imperial College School of Medicine, St. Mary’s Hospital, London, UK. J Vasc Surg, 2000; 32: 284-92
  4. Intermittent Calf and Foot Compression Increases Lower Extremity Blood Flow.” Eze, A.R.; Comerota, A.J.; Cisek, P.L.; Holland, B.S.; Kerr, R.P.; Veeramasuneni, R.; Comerota, A.J. Jr. Presented at the 24th Annual meeting of the Society for Clinical Vascular Surgery; March 1996. Am J Surg 1996; 172:130-135
  5. Optimum Intermittent Pneumatic Compression Stimulus for Lower-limb Venous Emptying.” Delis, K.T.; Azizi, A.A.; Stevens, R.J.G.; Wolfe, J.H.N.; Nicolaides, A.N. Eur J Vasc Endovasc Surg 19, 261-269 (2000).
  6. Improvement in Walking Ability, Ankle Pressure Indices and Quality of Life in Vascular Claudication Using Intermittent Pneumatic Foot and Calf Compression; A Prospective Randomized Controlled Trial with 1 Year Follow-up.” Delis, K.T.; Nicolaides, A.N.; Cheshire, N.J.W.; and Wolfe, J.H.N. Academic Vascular Surgery, St. Mary’s Hospital, London, UK. Presented at the Vascular Surgical Society of Great Britain & Ireland, Nov. 2000, London Arena.
Share Button

Compressing Ischemic Limbs and Why It’s Beneficial

To download a printable PDF of this article, click here:  Compressing Ischemic Limbs and Why It’s Beneficial

The Misconception

Is it true that arterial occlusive disease is an absolute contraindication for intermittent pneumatic compression (IPC)?

The Answer

Not at all!

Unfortunately, many medical professionals are under the impression that applying even a small external pressure to an ischemic limb with reduced distal arterial pressures may serve to reduce or completely stop the already-compromised blood flow. This article presents strong evidence that, contrary to popular belief, IPC can bring life-changing benefits to those who cannot undergo revascularization.

History

Part of the reason this dogma exists is because, for many who consider it, applying IPC to ischemic limbs seems counterintuitive and likely dangerous. Also contributing to this myth are the literature reviews written by investigators as far back as 1934 who showed a poor understanding of the physiological mechanisms. Though these measured acute effects of compression on increased blood flow in ischemic limbs and relief of symptoms, the assessments made about IPC therapy were muddled due to the use of a great variety of compression schemes and devices. This lack of clarity resulted in literature that only served to feed misgivings about IPC as a treatment modality.

Physiological & Optimization Studies | ACI Medicalarteriovenous pressure gradient

To demystify the true value of IPC, our goal was to determine the physiological mechanisms of action, to optimize IPC design for maximal acute effect, and to determine if there is a clinical benefit to patients with lower extremity ischemic disease.

We started with physiological studies1 with compression applied to the dependent limb, which showed these acute mechanisms:

  • Increased arterial-venous pressure gradient
  • Reduced peripheral resistance
  • Abolition of the veno-arteriolar reflex

Further studies2 concerned optimization:

  • Pressure:  at least 120 mmHg
    This high pressure is required to empty the veins in the dependent limb, which temporarily reduces venous pressure to near zero and increases the arterial-to-venous pressure gradient and therefore, flow. Reducing venous pressure also serves to temporarily abolish the veno-arteriolar reflex, which allows for arteriolar dilation.
  • Timing:  3 second pulses followed by 17 seconds of low pressure
    An essential requirement for an arterial pump is the ability to quickly reach inflation and deflation pressures with rise times of 0.25 to 0.30 seconds and fall times under 0.5 seconds.  This rapid squeeze and release creates blood velocities that apply shear stress to the endothelium which releases nitric oxide and further supports the large acute vasodilatory effect in the arterioles.
  • Compressed tissues:  foot, ankle and calf regions
    In order to maximize blood flow through the major arteries and to the toes where ischemic disease often presents, we found that a circumferential foot bladder including the ankle should be compressed first, followed one second later by compression of the calf with a relatively large asymmetrical bladder.

Randomized Controlled Trials | ACI Medical

Intermittent Claudication

Once the arterial IPC device was optimized, three randomized controlled trials3 were performed on patients with intermittent claudication. Not only did these trials yield significantly increased walking distances of two to three times, but also sustained “permanent” improvements begged the question, “What long term mechanisms might be at work?”

Limb Salvage due to Arteriogenesis

Further studies4 showed that arteriogenesis (the opening of collaterals) was responsible for improved ABI’s, PVR’s, toe pressures and popliteal flow. A recently published study from 20105 reported a 94% limb salvage rate at 3.5 years in patients who were unable to undergo revascularization procedures.

Arterial Assist Device, NOT Lymphedema Pump

ArtAssist Arterial Assist Device

ArtAssist®…The Arterial Assist Device®

Today, it is widely-known that IPC devices are designed for prophylaxis against deep vein thrombosis (DVT) and for treatment of lymphedema. However, the understanding behind these devices does not coincide with our exploration of IPC to treat severe forms of arterial disease. Lymphedema and DVT devices do not apply enough pressure to the dependent limb to adequately empty the veins, nor do they apply and release pressure rapidly enough to stimulate release of nitric oxide (NO). While such devices will not significantly improve blood flow in the ischemic limb, it is difficult to say whether they would be harmful without further study.

References in this Publication

  1. Effect of intermittent pneumatic foot compression on popliteal artery haemodynamics. Delis, K.T.; Labropoulos, N.; Nicolaides, A.N.; Glenville, B.; and Stansby, G. Imperial College School of Medicine, Academic Vascular Surgery, St. Mary’s Hospital, London, UK. Eur J Vasc Surg, p. 270-277, vol. 19, no. 3, March 2000.
  2. Optimum intermittent pneumatic compression stimulus for lower-limb venous emptying. Delis, K.T.; Azizi, A.A.; Stevens, R.J.G.; Wolfe, J.H.N. and Nicolaides, A.N. Irvine Lab for Cardiovascular Investigation and Research Academic Vascular Surgery, Imperial College School of Medicine, St. Mary’s Hospital, London, UK. Eur J Vasc Endovasc Surg 19, 261-269 (2000).
  3. Improvement in walking ability, ankle pressure indices and quality of life in vascular claudication using intermittent pneumatic foot and calf compression:  a randomized controlled trial. Delis, K.T.; Nicolaides, A.N.; Cheshire, N.J.W.; Wolfe, J.H.N. St. Mary’s Hospital, London, UK. British Journal of Surgery December 2002; Volume 88, Issue 4:605-606.
  4. Angiographic improvement after rapid intermittent compression treatment (ArtAssist®) for small vessel obstruction. Van Bemmelen, P.; Char, D.; Giron, F.; and Ricotta, J.J. Dept. of Surgery, Div. of Vascular Surgery, State University of New York at Stony Brook, NY. Ann Vasc Surg 2003; 17:224-228.
  5. Sequential compression biomechanical device in patients with critical limb ischemia and nonreconstructable peripheral vascular disease. Sultan, S.; Hamada, N.; Soylu, E.; Fahy, A.; Hynes, N. and Tawfick, W. Department of Vascular and Endovascular Surgery, University College Hospital, Galway, Journal of Vascular Surgery 2011; 54:440-447.
Share Button

ArtAssist® Arterial Pump Technology

Home-use compression device for patients with

Peripheral Arterial Disease

The ArtAssist Arterial Pump Device

The reason we named it “ArtAssist®” is because this specially engineered pump and cuff system gives patients’ limbs exactly what they need to heal:  more arterial blood flow. The ideal candidate for this uniquely optimized, completely non-invasive therapy suffers from severe symptoms of peripheral arterial disease – arterial occlusive disease of the upper and lower extremities. In a mere matter of weeks, patients see dramatic improvements, such as lessening of pain and wounds that finally begin to heal as a result of the improved circulation that ArtAssist®…the Arterial Assist Device® promotes. In as little as 90 days, daily usage of the ArtAssist® device can result in permanent improvements to the treated limb’s arterial circulation.

Share Button
Footer: