Thermoelectric Technology for Cold Therapy

The Safe & Effective Use of Thermoelectric Technology for Cold Therapy

ThermoTek believes that a multi-modality approach to post-operative, orthopedic rehabilitation is the most clinically effective method of addressing DVT prevention, edema reduction and pain management. When DVT prophylaxis, compression and thermal therapy are combined within the same unit, patient compliance and ease of use are increased.

One such modality within the VascuTherm is cryotherapy. Cryotherapy, also known as cold therapy, is one of the most widely-used treatment methods for certain muscle and joint injuries.

Cold Therapy Devices

 Cold therapy devices are typically prescribed by doctors, such as orthopedic surgeons and podiatrists, after certain surgical procedures to minimize pain and swelling and encourage mobility. Cryotherapy is commonly used to treat joint pain and post-surgical swelling in areas such as the ankles, feet, wrists, hands, knees, and shoulders. Cryotherapy machines circulate cold water around these areas after surgery.

Injuries Caused by Ice-based Cryotherapy Systems

If cold therapy devices are used too long, or at too cold of a temperature, it can result in serious injuries such as nerve damage, chronic pain, or frost bite. With little or no instruction or warnings, patients may subject the skin and underlying nerves to very cold temperatures for extended periods of time. Because ice therapy can desensitize the affected area, serious injuries can occur without the patient's immediate knowledge. Case studies have documented this injury pattern.

1st - What occurs at the cellular level:

Soft tissue trauma from injury, overuse, or surgical intervention causes an inflammatory response. At the cellular level, trauma causes disruption at the cell wall and can damage the cell and surrounding cells. As a response, the cell attempts to repair itself using anaerobic metabolism, which cannot be sustained. Because of this, the damaged cell cannot regulate the concentration gradients and allows water to pass through. As water dilutes the cells, the body releases a number of chemicals to correct the issue and get rid of cellular debris. As this happens, vasodilation occurs, increasing blood flow and transporting of fluid to the inflamed area. This process accounts for the redness and swelling sometimes associated with inflammation.

2nd - Cold therapy is an effective modality:

By utilizing cold therapy, the temperature of the tissue is lowered and the rates of the chemical reactions that actually cause the inflammation are slowed. Therefore, more cells survive, the damage slows, and healing is accelerated.  The cold also acts as an analgesic and reduces the pain from any inflammation and the associated swelling.

3rd - Safety considerations when using cold therapy:

It is important to note that cold therapy is effective only if used properly. Using a device that is too warm is not therapeutic, while using a device that is able to get too cold can cause damage to the tissue and nerves. The VascuTherm is one of the only ice-free devices available on the market, so temperature is precise and stable, therefore removing the worry of running out of ice or running another device at a low temperature that could potentially cause cold injury. The VascuTherm is regulated to operate between specific temperatures (43F-50F), therefore significantly reducing any risk of cold injury. The technology used by the VascuTherm is referred to as thermos-electric cooling.

The Solution Thermoelectric Cooling

Thermoelectric coolers (TECs), also known as Peltier coolers, are solid-state heat pumps that utilize the Peltier effect to move heat. Passing a current though a TEC transfers heat from one side to the other, typically producing a heat differential of around 40°C—or as much as 70°C in high-end devices—that can be used to transfer heat from one place to another.

The principle of thermoelectric cooling dates back to the discovery of the Peltier Effect by Jean Peltier in 1834. All electric current is accompanied by heat current (Joule heating). What Peltier observed was that when electric current passed across the junction of two dissimilar conductors (a thermocouple) there was a heating effect that could not be explained by Joule heating alone. In fact, depending on the direction of the current, the overall effect could be either heating or cooling. This effect can be harnessed to transfer heat, creating a heater or a cooler.

When two conductors are placed in electric contact, electrons flow out of the one in which the electrons are less bound, into the one where the electrons are more bound. Current passing across the junction results in either a forward or reverse bias, resulting in a temperature gradient; Cold vs. Heat! If the temperature of the hotter junction (heat sink) is kept low by removing the generated heat, the temperature of the cold plate can be cooled by tens of degrees.

In practice many TEC pairs (or couples) are connected side-by-side, and sandwiched between two ceramic plates, in a single TEC unit. VascuTherm contains an array of TEC pairs; or thermoelectric chips.

The Benefits of Thermoelectric Cooling

While refrigerators and air conditioners utilize compressors, condensers, and liquid refrigerants to lower temperature; solid-state cooling (like the VascuTherm) utilizes DC power, heat sinks, and semiconductors. This fundamental difference gives solid-state thermoelectric coolers the following advantages over compressors:

  • No moving parts. Therefore they require little or no maintenance. Ideal for cooling parts that may be sensitive to mechanical vibration.
  • No refrigerants, such as potentially harmful CFCs. Therefore environmental and safety benefits.
  • Enables reduced, low-noise operation of cooling fans, while providing greater cooling power.
  • Suitable for manufacture in very small sizes. Therefore ideal for microelectronics.
  • Lightweight.
  • Long life. Exceeds 100,000 hrs MTBF (Mean Time Between Failures).
  • Controllable (by voltage / current).
  • Small size.
  • Fast, dynamic response.
  • Can provide cooling below ambient temperature.



Clinical Papers, Studies and other Informative Materials in Support of Cold/Compression/DVT Prophylaxis

ThermoTek has developed a clinical white paper, and links to various studies that support the use of cold, compression, and/or DVT prophylaxis; to help physicians and other healthcare professionals understand the value of the VascuTherm. Click the title of each to download the document(s):

  1. Efficacy and Cost Analysis of Combined Thermal, Compression, DVT Preventative Therapy for Post-Surgical patients

This is a clinical white paper authored and developed by ThermoTek, Inc.; the document describes the clinical & economic benefits of the VascuTherm for thermal, compression & DVT prophylaxis.

  1. Combined Intermittent Pneumatic Leg Compression and Pharmacological Prophylaxis for Prevention of Venous Thromboembolism in High Risk Patients

This Cochrane Collaboration of eleven clinical studies, the results illustrate that the combined use of pneumatic prophylaxis & pharmacological prophylaxis reduce the incidence of PE and DVT 4% to 1%.

  1. Thromboprophylaxis in Orthopedic Surgery: How Long is Long Enough

This clinical study, published in the American Journal of Orthopedics, presents evidence that 45% to 80% of all symptomatic VTE events occur after hospital discharge. The author further describes that extended-duration VTE prophylaxis for 28-35 days reduces the risk for late VTE by up to 70%. Most patients are in their homes between post-op day 3 and post-op day 35.

  1. Identifying Patients at High Risk for Venous Thromboembolism Requiring Treatment after Outpatient Surgery

This research concludes that a 30-day VTE risk occurs after outpatient surgery, and provides a risk assessment for identifying such patients. The study concludes that the highest risk patients undergoing outpatient surgery have an almost 20-fold increase in the risk of VTE.

  1. Venous Thromboembolism in the Outpatient Setting

This investigative study reviewed the results of 1,897 patients with a confirmed episode of VTE. In all, 73.7% of patients developed VTE in the outpatient setting. 67.0% experienced VTE within 1 month of hospital discharge.

  1. Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians; Evidence-Based Clinical Practice Guidelines

This is the full executive summary produced by the American College of Chest Physicians; listing their evidence-based clinical practice guidelines for the prevention of DVT & PE.

  1. Table - ACCP Evidence-Based Clinical Practice Guidelines

This is the abbreviated table of the ACCP’s guidelines on DVT prevention. The table references 9 categories where intermittent pneumatic compression is recommended for the prevention of DVT & PE.

  1. Table – AAOS Clinical Practice Guideline of Recommendations – Preventing Venous Thromboembolic Disease in Patients Undergoing Elective Hip and Knee Arthroplasty

This is the abbreviated table of the American Academy of Orthopedic Surgeons (AAOS) clinical practice guidelines on DVT prevention.

  1. Venous Thromboembolism Risk Factor Assessment

This is the actual Venous Thromboembolism Risk Factor Assessment developed by Joseph A. Caprini, MD. MS, FACS, RVT, Northwestern University, Feinberg School of Medicine. The front page of the risk factor assessment is a scoring table of patient comorbidity factors related to DVT/PE development. The back page actually scores the patient in to one of four Risk Levels.

Thrombosis Risk Assessment as a Guide to Quality Patient Care

This clinical article, written by Joseph Caprini, MD, delineates the background, research, interpretations, and case studies that went into the development of the Caprini Venous Thromboembolism Risk Factor Assessment.