Auto-Tourniquet System for LastWatchCorp

This page highlights excerpts from an ongoing collaboration between Pixel and Timber and the emergency medicine genius behind LastWatchCorp, a Cincinnati-based startup that is changing the way major traumatic injuries are treated on the battlefield. Over the course of this ongoing project, Pixel and Timber has designed, developed and prototyped several versions of Dr. Grundy’s life-saving invention — a powered mechanical tourniquet system designed for combat use.

PRoject Background

Dr. David Grundy, MD, FACEM, FRSA, Major (ret) US Army & Founder of LastWatchCorp

Dr. David Grundy, MAJ (ret) US Army, is a multiple tour combat veteran. In 2018, Dr. Grundy began thinking seriously about device-based means to save the lives and salvage the limbs of warfighters with severe extremity injuries.

In modern combat zones, threats from IEDs, blast effects, and military caliber firearms make severe injuries to the extremities some of the most common causes of U.S. and coalition fatalities. During his combat tours to Iraq, Dr Grundy frequently encountered and treated these injuries. Also during this time, he lost friends and comrades to them. Improving care and increasing survival for these patients is a deep passion for him.

After a period of experimentation, end-user feedback, and design evolution, Dr. Grundy has invented and has patents pending on a powerful, generally applicable, and cost-effective means to address these injuries on the battlefield and save lives.

For more information about Dr. Grundy and his work:

www.lastwatchcorp.com

The Device

Dr. Grundy’s Auto-Tourniquet has enjoyed many embodiments. Each is designed to provide rapid hemostasis by automatically tightening a wide belt around an injured limb. The most recent versions of this device are designed to work with an integrated tourniquet built into every army combat uniform (ACU), at the base of each extremity.

“All military uniforms should also function as life-saving, hemostatic devices.”

— Dr. David Grundy, MAJ (ret) US Army

An exploded view drawing of the 001 version of the device.

The Grundy Integrated Tourniquet Uniform (ITU) is a low-cost upgrade to the standard military combat uniform that adds a quick and effective means of temporarily stopping major extremity bleeding from battlefield trauma. In it, a “captured strap” is emplaced in a low friction internal sleeve at sites over each upper arm and upper thigh. A loop and tab of the strap passes through a low friction guide plate and lays flat, secured by a velcro attachment. In ordinary daily use, this system is invisible to the wearer and will wear exactly like a standard ACU uniform. In the case of major extremity injury with heavy bleeding however, this tab is pulled up to make it accessible to the Auto-Tourniquet (AT) Driver.

The Auto-Tourniquet (AT) Driver is a small, rugged device which quickly tensions the band and tightens the tourniquet until bleeding stops. It uses a small gearbox motor powered by a lithium polymer battery to drive a series of toothed rollers. When clamped to the tab protruding from the ITU, these rollers advance the strap, constricting it circumferentially around the injured limb. Force feedback prevents over- or under-tightening of the Auto Tourniquet, and the wide strap prevents local necrosis of the tissue beneath it. Patents are pending on the Auto-Tourniquet System and its Integrated Tourniquet Uniform.

The Auto-Tourniquet system can be deployed in seconds. The images below describe the simple process of its use.

Step 1: Wounded Soldier

Step 2: Release tab

Wounded soldier pulls integrated loop loose from velcro arm patch to expose the AT tab.

Step 3: Expose tab

The AT tab is erect and ready for the AT Driver.

Step 4: Position AT Driver

Wounded soldier places AT Driver jaws around erect tab.

Step 5: Install AT Driver

Wounded soldier squeezes AT Driver to clamp jaws around exposed tab.

Step 6: Activate AT Driver

Wounded soldier activates AT Driver with the press of a button.

Step 7: Hemostasis

AT Driver advances strap to constrict tourniquet band within uniform until hemostasis is achieved.

Product Development

Over the course of this collaboration, Pixel and Timber has developed several embodiments of Dr. Grundy’s life-saving technology, including both mechanical and electromechanical versions. Our team has led collaborative ideation sessions, designed and prototyped new versions of the device, supported the development of IP, and presented to end-users of the technology. The images and text below capture a small fraction of this ongoing work.

REvision #001

The first embodiment of the electromechanical version of the device was meant to interact with auxiliary straps of any size. This means that this version could also be used by civilian personnel in a mass casualty event. The device could accommodate bands up to the size of a leather purse strap or a waist belt. To make it universally portable, the device was sized to fit in a magazine pouch.

Revision #002

The 002 version of the device introduced the Integrated Tourniquet Uniform (ITU). Integrating a strap of a common size greatly simplified the design of the AT Driver, decreasing its cost and increasing its projected reliability. The Grundy Integrated Tourniquet Uniform (ITU) is comprised of a wide fabric band sewn into a low friction pocket wrapped circumferentially around the soldier’s arm. The images below include some details of this system, including the location of each strap. They also include several renderings comparing the 001 & 002 versions of the device.