Evaluation of possible battlefield tourniquet systems for the far-forward setting

Military Medicine, May 2000 by Calkins, Mark Dennis

A significant number of casualties in previous conflicts died from peripheral vascular wounds. A well-designed tourniquet could possibly have prevented these deaths. The objective of this study was the identification of such a tourniquet. A survey of Special Operations corpsmen established important characteristics necessary in an ideal tourniquet. Because most available devices do not and patented ideas could not meet these criteria, a number of prototypes were developed. Seven potentially satisfactory tourniquets were evaluated by 15 Navy SEAL corpsmen. The success and timing of placement were recorded, and a follow-up questionnaire was completed. Of the several successful tourniquets, two were preferred. Tourniquets incorporating a windlass technique take longer to place and often fail when placed with only one hand. New, relatively simple tourniquet devices incorporating bladder and ratchet mechanisms can significantly improve tourniquet performance.

Introduction

During the Vietnam War, a major cause of death was exsanguination, accounting for about half of all combat deaths. Although most of these injuries were vascular chest and abdom final wounds, fully 20% were peripheral vascular injuries.1 These deaths were potentially preventable with timely application of a tourniquet. In other words, a properly designed tourniquet could possibly have prevented 10% of total combat deaths. In the civilian environment, tourniquet use is discouraged because of the potential to cause further limb damage. Additional medical care providers and short transit times allow for a designated individual to hold pressure until definitive treatment is reached. In contrast, in the military, long evacuations and limited providers, who are often needed to fight, make tourniquet use necessary.

Obviously, the purpose - and hence the most pressing requirement - of any tourniquet is to consistently occlude arterial blood flow. Damage to an artery, which carries blood under high pressure from the heart to the rest of the body, can rapidly lead to exsanguination and death. Massive tissue avulsion, with or without arterial injury, may do the same. To be effective, a tourniquet must be designed so that it may be placed easily and quickly. The device must also be compact and light enough to be carried by soldiers. Simplicity and ruggedness are necessities. Although upper extremity wounds may not require tourniquets as often as lower extremity wounds, significant hemorrhage is still a possibility. Therefore, further requirements are the ability to use the device on both upper and lower extremities and single-arm operation, so that a casualty who has a wounded upper extremity can, if still alert, apply the device without assistance.

Unfortunately, tourniquets widely used by the U.S. military do not meet these criteria. The cravat and cotton strap (non-- pneumatic tourniquet; National Stock Number [NSN) 6515-00-- 383-0565) are capable of occluding arterial blood flow when placed by another person. However, when placed on oneself, they take significant time to position, are difficult to operate, and often do not stop blood flow. In response to this need, we evaluated currently available systems and several new prototypes for functionality in the far-forward environment.

Methods

Needs Survey

A simple needs survey was developed to discern which attributes of a military tourniquet system were most desirable. Specially trained (18-Delta) Navy SEAL and Reconnaissance combat corpsmen were asked to rate 15 design features (Table I). These ranked characteristics were used to assess the battlefield potential of tourniquets evaluated in this study.

Commercial Product Search

A comprehensive search was performed to discover commercially available tourniquets through review of emergency medical equipment catalogs, the Internet, the U.S. National Stock Number index, and personal communication with both military and nonmilitary medical care providers. The limited variety of available devices probably reflects their limited use in the civilian environment. In addition, a patent search was conducted to uncover any existing designs that could potentially meet some of the listed requirements.

The National Stock Number list contains four tourniquets. The two pneumatic devices are large, expensive, and inappropriate for the battlefield (NSN 6515-01-287-0607, cost = $5,214; NSN 6515-00-383-0400, cost = $362). The 1.5-inch-- wide green cotton strap shown in Figure 1 (nonpneumatic; NSN 6515-00-383-0565) is the only tourniquet intended for field use in the event of peripheral vascular injury. To apply the device, the loose end of webbing is fed through the buckle. To tighten, the loose end is pulled until a snug fit is achieved. To loosen or remove, the buckle is pinched, releasing the webbing. This device does not reliably stop arterial flow, as assessed by palpation of distal peripheral pulses, even when others apply the device. It may function appropriately when windlassed. Figure 2 shows the 1-inch-wide blue rubber elastic tourniquet (NSN 6515-01-- 146-7794) used for blood draws and intravenous catheter placement. This product does not allow for arterial occlusion.