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Limb Cooling Device to Preserve Ischemic Extremity for Prolonged Field Care

Description:

TECHNOLOGY AREA(S): Bio Medical 

OBJECTIVE: Develop a light-weight, small cube, field-ready limb cooling device capable of reducing limb temperature to 10-15°C for up to 24 hours 

DESCRIPTION: A capability is sought to extend the duration that a tourniquet can be safely used on limbs following extremity vascular injury, this may include mangled and amputated limbs. The use of tourniquets during the wars in Iraq and Afghanistan has significantly improved survival rate for exsanguinating extremity injuries [1]. Currently under standard conditions, tourniquet safety is at least 2 hours, and possibly even up to 6 hours [2]. However, future operational scenarios include delayed evacuation of combat casualties, which could significantly extend the duration of tourniquet application and resulting ischemic injury. Technologies are needed to mitigate damage caused by long-term limb ischemia due to vascular injury and the use of tourniquets, as well as to mitigate the development of extremity compartment syndrome and reduce the development of rhabdomyolysis. Limb cooling has been shown to dramatically reduce local ischemic damage, systemic injury [3], and reduce the development of rhabdomyolysis as a result of severe muscle damage leading to multi-organ dysfunction or failure [4]. Successful completion of this project should result in a field-ready cooling device capable of rapid limb cooling and maintenance of a target temperature over a prolonged period. 

PHASE I: Design/develop an innovative concept along with the limited testing of a prototype non-invasive device capable of reducing deep muscle temperature to between 10-15°C as rapidly as possible without causing superficial thermal damage, and to maintain deep muscle temperature within that range for at least 12 hours, assuming an ambient temperature of 20°C. Deep muscle temperature is operationally defined as the temperature of the muscle closest to the bone based on a reference human thigh with a diameter of 18.78 cm. It can also be assumed that there is no blood flow. The demonstration does not require live animal use but could be performed using limbs from large animal (ex-vivo) or appropriately sized physical model. 

PHASE II: Required Phase II deliverables: 1) Using results from Phase I, demonstrate the operation of a prototype in an ischemic hindlimb of a large animal in vivo. The DOD Directive 3216.1, dated April 17, 1995, provides policy and requirements for the use of animals in DOD-funded research. 2) Based on the results from (1), construct and complete design suitable for use on a human upper and lower extremity. The device must be portable, lightweight (<2 lbs), self-contained, power requirement is replenishable/rechargeable). A plan must be included for any device requiring the addition of coolant (e.g. water) or the disposal of any generated waste. The device should be configurable to accommodate upper or lower extremities and to allow easy access to injured limb for visual inspection and treatment, and be designed for easy reapplication. The Phase II commercialization plans should include a regulatory pathway for FDA clearance. 

PHASE III: Transition prototype into a functional, field-ready limb cooling device to assist medics, physician’s assistants, nurses, and physicians in triage and management of casualties with extremity trauma in a far forward environment (role of care 1 and 2). The device should be of great commercial interest for all branches of the armed services as well as civilian pre-hospital first responders and mass casualty incident (MCI) response teams worldwide. The small business will need to work with the Air Force Medical Modernization Division, Air Mobility Command to develop an air worthiness/safe-to-fly testing plan. The small business should have in plans to secure funding from non-SBIR government sources and/or the private sector and a transition plan that will bridge the gap between laboratory-scale innovation and entry into a recognized Food and Drug Administration (FDA) regulatory pathway leading to commercialization of the prototype into a viable product for sale in the military and /or private sector markets. 

REFERENCES: 

1: Eastridge, B.J., et al., "Death on the battlefield (2001-2011): implications for the future of combat casualty care." J Trauma Acute Care Surg, 201 73(6 Suppl 5): S431- https://www.ncbi.nlm.nih.gov/pubmed/23192066

2:  Drew, B., et al., Tourniquet Conversion: A Recommended Approach in the Prolonged Field Care Setting. J Spec Oper Med, 201 15(3): 81- https://www.ncbi.nlm.nih.gov/pubmed/26360360

3:  Skjeldal, S., et al., Local hypothermia during ischemia or reperfusion in skeletal muscles. Res Exp Med (Berl), 199 193(2): 73-80. http://www.ncbi.nlm.nih.gov/pubmed/8516565

4:  Peiris, D., A historical perspective on crush syndrome: the clinical application of its pathogenesis, established by the study of wartime crush injuries. J Clin Pathol, 201 70(4): 277-28 https://www.ncbi.nlm.nih.gov/pubmed/27920043

KEYWORDS: Extremity Trauma; Vascular Trauma; Field-ready; Tourniquet; Hypothermia; Ischemia; Limb Preservation; Rhabdomyolysis 

CONTACT(S): 

Thomas Walters, Ph.D. 

(210) 539-2726 

thomas.j.walters22.civ@mail.mil 

Kathy Ryan, Ph.D. 

(210) 539-7970 

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