JASON D. HEINER and ERIC J. CHIN

Overview

War zones are unpredictable and austere environments that present unique challenges to medical providers. The hazards of combat as well as common nontraumatic pathology must be cared for in a diverse range of settings, from the combat medic caring for a wounded casualty while under enemy fire to the physician caring for critically ill patients in a forward-deployed temporary field hospital.

During previous conflicts, as recently as the late 20th century, medical diagnostic imaging on the battlefield was mostly limited to sparsely available plain radiography. The introduction of ruggedized handheld ultrasound devices in the late 1990s transformed the diagnostic capability on the modern battlefield.^1,2 Although still vulnerable to the harsh environment of war zones, these lightweight portable units now enhance medical care for diverse battlefield settings and medical providers. The use of ultrasound in war zones often reflects its use in traditional hospital environments; however, the unique challenges and constraints of the battlefield give rise to unique applications.

Deployable ultrasound devices and technology

Ultrasound imaging for field military use became feasible in 1999 with the release of the SonoSite 180 machine (SonoSite, Bothell, WA), which was developed with a grant from the United States government for military use, with specifications that it be “a field device, hand-held by soldiers or medics, producing high quality images which could be downloaded via satellite to physicians at base hospitals” (Figure 49-1).^1,2 To achieve these goals and be practical for field use, designers of this and subsequent ultrasound machines have sought to be lightweight and easy to transport, rugged, and versatile in their power source.

Modern battlefield ultrasound machines with a transducer attached typically weigh 2.5 to 3.5 kg, with durable and/or flip-top screens as well as a carrying handle incorporated into the body of the device. High image quality and multiple modes and applications enable replication of typical sonographic capabilities. Screens must be able to ensure that images are viewable in varying degrees of ambient lighting. Transport in a durable case aids in protecting the elements of both the device and its transducers. Users should consider their anticipated working environment and size/weight requirements when acquiring an ultrasound machine for use in a war zone and must modify their method of machine transport to their setting. A medic in the field needs to ensure device protection and rapid accessibility when injury occurs, whereas a physician in a combat hospital may be able to establish more permanent locations for the device. Ultrasonography often occurs in unique situations, such as medical evacuation via ground transport by armored vehicle or air transport by helicopter, but requires providers to be prepared to adapt their equipment to their situational requirements.

Transport for accessories, in addition to the primary ultrasound machine, must also be planned. Experience with ultrasonography in war zones has demonstrated the usefulness of low-frequency curvilinear probes, high-frequency linear probes, and endocavitary transducers for applications mirroring the civilian hospital setting. Consistent access to external electrical power needed to run the device is rarely guaranteed in many of the austere settings of war, and access to reliable device-compatible battery power is imperative. Over time (particularly in extreme conditions), battery life is expected to wane. Additional batteries for extended missions are a prudent precaution when timely access to more batteries or compatible sources of electrical power is uncertain.

War zone ultrasonographers may be equipped with capable technology and basic image acquisition and interpretation training but may lack the expertise to interpret some aspects of the images obtained. Via telesonography, electronic communication tools allow the transmission of ultrasound images from the point of care to specialists for further image interpretation. Several battlefield methods have been described.2–5 Image file capture can be achieved by the ultrasound machine or a secondary device, such as a camera or camera-equipped phone. Image file transmission has been described by phone, landline, and by wireless relay from a portable vest-mounted transmitter to a receiving antenna and then to a satellite.⁶ The clinical impact of telesonography depends on the speed of image transmission, clarity of the final received image, and the timeliness of pertinent image interpretation.

Settings of patient care during war

Medical care is delivered to battlefield casualties in several unique settings, from the point of injury to care during evacuation out of the war zone. Each of these settings can pose exceptional challenges to a unique combination of care providers with varying medical skills and familiarity with ultrasound (Table 49-1). These variations allow diverse opportunities for ultrasound to impact the care of injured or ill patients.