Introduction

Advancements in medical technology never cease. The same is true for combat medicine, in which new innovations and technologies are aimed at one common goal: saving soldiers' lives. The 212th Mobile Army Surgical Hospital (Forward) had the opportunity of being the first forward-deployed unit to field the Life Support for Trauma and Transport (LSTAT), an innovative piece of equipment, in conjunction with the Walter Reed Army Institute of Research (WRAIR) during their summer 2000 deployments to Kosovo. The 212th Mobile Army Surgical Hospital (MASH) was issued the LSTAT for implementation in the real-world military medical arena (Fig. 1).

While in Kosovo, the goals were multifaceted. The MASH fully tested the applicability and utilization of the LSTAT. Moving the LSTAT from the controlled field exercise environment to fullfledged use in a deployment environment saturated the fielding team with new data and feedback. A full case study was presented from the compilation of all tracked and forwarded documentation, the first away from the test bed.

The LSTAT is a self-contained, transportable, critical care platform that integrates a combination of off-the-shelf medical devices. The life support needs of the critically injured patient during medical evacuation are the driving force behind the LSTAT platform design. Evacuation problems directly related to the increased mobility of U.S. forces identified during Operation Desert Storm were significant. The forward line of battle moved at unprecedented rates that increased the evacuation distance between the troops and medical assets.I The concept of the system is to provide expedient, high-quality, life-sustaining care through all levels of the evacuation chain to decrease mortality and morbidity on the battlefield, even when evacuation distances are increased.

Current doctrine states that patients must be stable before evacuation.2,3 Thus, stabilization of the critically ill patient in the field medical treatment facility before transport is required. Stabilization of the critical patient can take days, resulting in increased work force, burden of logistical support, and bed availability at the holding treatment facility. In addition to the LSTAT's use as a critical care transport platform, exploration for other uses during this deployment included (1) a trauma bed in the emergency medical treatment area of the MASH, (2) an intrahospital transport bed, and (3) an intensive care unit (ICU) bed. During this deployment, the LSTAT was not used as an instrumented operating room (OR) table, although it had been used for this purpose in previous training exercises.

The LSTAT components include a ventilator, suction apparatus, oxygen blending system, three-channel intravenous infusion pump, physiological monitor (Propaq), hand-held clinical blood analyzer, and automated external defibrillator. Rather than redesign numerous portable medical components, the LSTAT design integrates state-of-the art, commercial standalone predicate devices previously cleared by the Food and Drug Administration. Training is greatly facilitated by the fact that these components are not new but rather off-the-shelf elements with which many clinicians are already familiar.

All of the components are connected to a fully network-capable, on-board computer system. A data-logging capability stores up to 72 hours of device settings and patient data. This information is gathered from the multiple physiological sensors, ventilator settings, and laboratory values and then stored on a miniature hard disk drive. A similar electromagnetic interference and shock-hardened central processing unit provides realtime signal-processing power. This allows every component to log subsystem utilization and patient monitoring data in a continuous and simultaneous format that can be downloaded and displayed locally or at a distance using the Internet.

The platform has a stand-alone, rechargeable power system that connects to different military power sources, including 110 V, 60. Hz/220 V, 50 Hz; 28V M997 ambulance, and UH-60 medical evacuation helicopter. Packaged together in a graphite composite shell cast molded to fit the carousel pans of the UH-60 helicopter and to fit securely in the transportation bay of the M997 are all of the features mentioned above. The LSTAT also accepts the standard NATO litter with spring-loaded latches on each of the four litter handles, which capture them automatically.

The 212th MASH welcomed the LSTAT and its WRAIR developers to the MASH's mission rehearsal exercise in Wiesbaden, Germany, in February 2000. The mission rehearsal exercise prepared the 212th MASH for its deployment to Camp Bondsteel, Kosovo, as part of Task Force Medical Falcon in support of Operation Joint Guardian. The WRAIR team, with the assistance of representatives from Integrated Medical Systems, Inc., spent countless hours training the MASH personnel. The personnel included clinicians, transport elements, and maintenance teams, who received in-service orientation briefings and worked directly with the LSTAT for invaluable hands-on experience.

The 212th MASH arrived at Camp Bondsteel on March 28, 2000. The WRAIR support team arrived to assist with the LSTAT program initiation on April 13, 2000. During the preparation phase, the communications network, work station, server configuration, and final system tests were completed. Prepositioned in one of the four trauma bays in the emergency medical treatment section, the LSTAT went operational. Between March 28 and July 1, 2000, the 212th MASH used the LSTAT in 15 cases, including gunshot wounds, myocardial infarction, cerebral vascular accident, mine strike, angina, dysrhythmias, seizures, and dyspnea. Uses included not only the care of patients inside the hospital but also during critical care transports.

There were three different categories of LSTAT use: trauma, major medical, and transport. This categorization allowed the critique of LSTAT performance in different aspects of use. Observations in these categories highlight its value and specific situations in which improvements could be made. The LSTAT was used during the treatment of six trauma patients, five major medical patients, and one transport patient. Included in the major medical category were two mechanically ventilated patients, one of whom was transported out of the hospital using the LSTAT.

The after-action survey gathered clinicians' subjective and objective information regarding the LSTAT. After transferring patients into the ICU, many nurses found it beneficial that everything (suction apparatus, Propaq monitor, etc.) was conveniently within reach. The litter, with all monitoring equipment, was very easy to transport to and from areas within the hospital. Without the LSTAT, it takes at least six people to transport a mechanically ventilated patient to other hospital areas using the wheeled litter system (WLS). The more equipment taken when moving a patient, the higher the risk for pulling wires, lines, and catheters and for damaging equipment during transport and treatment. Only two personnel are required, using the WLS, to transport the LSTAT with all components in use. This frees up personnel and reduces the risk of injury to the patient and other hazardous events, such as accidental extubation.

When conducting a traditional intrahospital transport, the movement of intravenous line poles requires much coordination. This can cause hazards because the hallways and doorways inside a field hospital are quite narrow. The LSTAT reduces this hazard by having the capability to attach up to four intravenous line arms to the LSTAT frame. The compact, integrated design directly increases available space around the patient during trauma resuscitation and critical care, because the immediate area is not draped with cables and lines. The LSTAT's compactness makes it very easy to prepare the patient for interhospital and intrahospital transport, which greatly reduces transport preparation time.

Monitoring capabilities for patients needing computed topography in radiology are necessary when using the LSTAT during intensive care and emergency treatment. Without disconnecting any monitors, the patient was wheeled beside, and then transported onto, the computed topography scanner bed. There is enough monitoring cable and ventilator circuit length to accomplish a complete body scan without disconnecting the patient from the LSTAT. LSTAT use reduces time in radiology by not requiring unpacking and packing of equipment to complete radiological procedures. This decreases the time before admitting the patient for life-saving surgery or to a more stable environment such as an ICU.

The completeness and compactness of the LSTAT is valuable when moving the trauma patient out of the emergency medical treatment area. The ability to track vital signs continuously on a trauma patient through multiple environments (emergency, radiology, OR, ICU, and transport) is extremely beneficial. A vital sign display program accompanies the secondary display. The program can generate a minute-by-minute computer printout from any personal computer.

The treatment of major medical patients and trauma requires very frequent blood chemistry and arterial blood gas readings. The portable blood chemical analyzer (I-Stat), which is capable of giving blood results for five different blood chemistry and arterial blood gas values, is convenient to have at the bedside and reduces times for patient treatment that is dependent on subsequent laboratory values. Incorporated in the overall data output are laboratory values the LSTAT computerized datalogging subsystem uploads from the I-Stat. A myocardial infarction patient required cardiopulmonary resuscitation (CPR) while on the LSTAT. The staff found the LSTAT to be a hard and flat surface, conducive for ideal compression technique.

The clinical staff recommended improvements for the LSTAT that would further enhance its usefulness and increase user effectiveness with major medical patients. Although the hardness of the LSTAT is ideal for CPR, this hard and flat surface creates a possible safety hazard for patients who may use the LSTAT for more than 1 hour awaiting transport. A regular litter will allow a certain amount of sag in the litter material. The sagging helps to cradle the patient and reduce the risk of patients falling off the litter, even when restrained with litter straps. Because of the hard, flat surface of the LSTAT, there is no sag to assist in cradling the patient. Therefore, even greater emphasis is placed on the use of litter straps, which is not always feasible during trauma resuscitation.

The centralized location of the monitoring equipment on the LSTAT has some disadvantages. During a code, or when a patient's condition is labile, many care givers are around the patient's bedside. This makes it difficult to monitor the patient using the Propaq monitor located at the headpiece of the LSTAT. The Propaq monitor was difficult to see because it is at waist level. The secondary display, as well as the Propaq monitor, was difficult to read from an angle. Even though the secondary display is designed to assist with data dissemination, its font size was too small to read at a distance, it had poor visibility, and at times, there were connectivity problems that prevented the secondary display from displaying any patient data.

Revising the software, which would facilitate easier visualization at a distance, could increase secondary display numerical font size. In addition, well-lit areas caused excessive screen glare on the secondary display. In a medical emergency, as many people as possible need to be able to see the cardiac rhythm and vital signs display. Because the secondary display screen is a liquid crystal display with 256 shades of gray, it is very difficult to obtain the correct contrast to make it seen easily at a distance. Introduction of the secondary display into very bright light, especially sunlight, caused the screen to "white out" and became impossible to read. Integrated Medical Systems, Inc., is evaluating three new secondary display models, which have color and high-contrast capability that should rectify this issue. The potential for setting up two secondary displays, one for trauma team viewing and another for documentation, would further exploit the LSTATs capability.

All monitoring and mechanical ventilator connections are located on the LSTAT headpiece on the side toward the patient. This can make it difficult to reach certain monitoring plug-ins and to change ventilator circuits while the patient is on the LSTAT. Preparing a trauma station for an anticipated patient is an extremely important aspect of trauma team readiness. The Propaq connectors are located at the base of the headpiece (Fig. 2) on the patient side of the LSTAT. One cannot place a litter on the LSTAT if the monitor cables are already connected. This creates a delay in obtaining vital signs when the patient arrives in the trauma bay. Both of these issues can be remedied if the connections were placed higher on the headpiece so that the litter could clear the protruding cable bases without causing damage to the monitor cables, which would also increase accessibility when changing monitoring cables and ventilator circuits.

The LSTAT platform is narrower than a standard field hospital bed. Although the LSTAT is beneficial for short ICU stays, if the time spent on the LSTAT is greater than a few hours, the narrow width makes it difficult to provide care. One must turn a patient for hygiene purposes and pressure sore prevention during intensive care treatment. When doing so on such a narrow platform, the chances of a patient falling off the stretcher are increased. When patients are supine, the narrow width does not allow enough room to place the patients' arms along their sides without the use of litter straps to secure them. Health providers do not routinely use litter straps on ICU patients in a standard field hospital bed. The required use of litter straps for the duration of an ICU stay can hinder care. Mechanically ventilated obese patients made this requirement evident during their ICU stays (Fig. 3).

The ventilator controls are exposed and located on the top of the headpiece. These controls are easily knocked or brushed up against, which could change settings accidentally. A solution could be a flip-top, clear, impact-resistant cover and controls receded farther into the headpiece. The respiratory therapist also felt that the ventilator controls were overly sensitive. When trying to adjust positive end expiratory pressure or respiratory rate, extremely small movements in the ventilator control dials resulted in a change much greater than desired. The respiratory therapist mentioned that the ventilator settings were sometimes difficult to "dial-in" because of oversensitivity.

Stand-alone Propaqs have the ability to print out vital sign trends and electrocardiogram strips. The headpiece encases the Propaq monitor, which prevents such printing. The LSTAT developers purposely decided that the printing module would not be included for weight reasons. In addition, the Propaq built into the headpiece dampens the audible alarms, which made them difficult to hear. An external speaker or amplification would correct the audible alarm volume level.

Another concern noted was the fact that the suction apparatus has too small of an aspirate container, which was easily filled in a very short time. The addition of an in-line 1,000-mL suction container increased volume but created lower suction pressure from the apparatus, which already had borderline suction pressure performance.

LSTAT use included two head and cervical spine injury patients arriving at the emergency medical treatment area secured on spine boards. The anesthesia staff and emergency room physician felt that it was difficult to intubate over the LSTAT headpiece. The next cervical spine patient was turned around so that the patient's feet were against the headpiece (Fig. 4). Although this facilitated ease of intubation, the change highlighted two other issues. The spine board would not sit flush on the LSTAT because the power source cable comes up 1.5 inches from the foot of the LSTAT (Fig. 5). The remedy would be to have the power cable exit the LSTAT sled from an angle directly horizontal from the foot of the LSTAT. Additionally, turning a patient around and intubating a patient in this manner places the anesthesia provider away from the ventilator controls, which is less than desirable.

After trauma use, cleaning of the LSTAT also became a problem. Blood would seep into the seams of the top plate and into the litter foot holders on the LSTAT. Placing a drainage hole in the bottom of the litter foot holders to drain blood and water could prevent pooling in the litter foot holders. Only the use of plastic sheeting prevented blood from accumulating in the seams of the LSTAT cover plate. Designing the cover plate to consist of overlapping joints would prevent body fluids from resting in the seams and facilitate cleaning, preventing infection control issues from arising.

A niche found for the LSTAT was the transportation of mechanically ventilated patients away from the hospital. The compactness greatly aided in transport. Individual monitoring and ventilator equipment was not spread out in the ambulance. This prevented equipment from falling and causing clinician or patient injury and equipment damage. The secondary display (Fig. 6) was extremely valuable during transport, allowing documentation, real-time monitoring of vital signs, and adjustment of ventilator settings while en route. The use of a remote personal computer local access network adapter card allowed a wireless connection from the LSTAT to the secondary display. The remote personal computer card connection allowed the secondary display to monitor the LSTAT at distances up to 50 feet.

With the LSTAT loaded in the ambulance, there is not enough room to see the Propaq monitor display and button functions without opening the rear door. The secondary display can show all vital signs and ventilator information, but because of FDA regulations, the secondary display cannot adjust the Propaq monitor settings such as alarm and blood pressure cuff cycle settings. When unable to see the Propaq function button labels, it is difficult to make changes to the Propaq monitor while the ambulance is in motion.

The LSTAT has no built-in warning system before system shutdown occurs as a result of depletion of the battery charge. A light system indicates if the internal battery is less than "1/4 FULL" and then "LOW." After reaching LOW, there are no other warnings before full system shutdown. An audible warning system that notifies at 30, 15, 10, and 5 minutes before power loss would be of significant value. This would give the treatment team time to locate a power source. Audible reminders are very important in a transport, trauma or critical care environment when many tasks are occurring simultaneously. The display and data-logging subsystem pad and screen are located on each side of the LSTAT. This location makes the data entry pad vulnerable to damage, especially while moving in and out of vehicles and aircraft. A small sliding metal panel would protect the display from harm.

The LSTAT platform sits atop support bars located on the WLS. The LSTAT raises the litter approximately 5 inches higher than a litter on the WLS without the LSTAT. The height of the LSTAT while positioned on a WLS was a great concern to surgeons and other health care providers. During medical emergencies, it was noted that portable chest radiographs were difficult to obtain because of the height of the LSTAT. The field portable X-ray machine is limited on vertical height adjustment, limiting the angle of radiation projection. The height also creates a significant drop when placing a patient onto an ICU bed. Shorter personnel have difficulty examining the patient, completing certain procedures, and performing CPR. The height concern was such a hindrance to some surgeons that they refused to use the LSTAT during trauma.

A design solution would be to cast mold the underside of the LSTAT, not only to fit the UH-60 patient litter pans, but also molded with cutouts that will allow the WLS support bars to fit up into the LSTAT sled (Fig. 7). This will bring the height of the LSTAT closer to that of a regular litter fitted on a WLS. It is strongly suggested not to modify or create any additions to the WLS to correct the LSTAT height issue. WLS modification could create even greater issues with availability and logistics.

Creating a specialized WLS specifically for the LSTAT would be cumbersome and could cause availability, tracking, and replacement issues that have the potential to become burdensome and reduce the overall effectiveness of the LSTAT package. Using specialized parts instead of the existing support bars of the WLS has the potential to create like problems with tracking and availability of those parts. When specialized parts are not available, they may negatively factor in the clinical decision to use or not use the LSTAT. The importance of using an unmodified WLS is crucial when a patient is placed on and removed from a WLS at every echelon of care throughout critical care transport. The existing WLS is universal throughout the field medical system within the U.S. Army.

The matter of the LSTAT's overall weight was raised before and after the fielding in Kosovo.4 After treating multiple patients, weight was a smaller concern than initially anticipated. In a combat support hospital environment, removing a trauma patient from a WLS is rare, even in the absence of the LSTAT. Upon entering the emergency medical treatment area (Fig. 8), placing the patient on the LSTAT prepositioned on a WLS occurs immediately. Use of a WLS facilitates transportation throughout the hospital (radiology, OR, and ICU).

In preparation for ground or air ambulance transport, the patient is wheeled as close to the vehicle or aircraft as possible before removing him or her from the WLS, minimizing the frequency of lifting the LSTAT. Even when it is necessary to lift the LSTAT, it comes with accessory handles to increase from a four-person to a six-person lift. The only instance in which weight became an issue was during intrahospital transfers. The LSTAT is very difficult to maneuver in tight spaces. Whereas a patient and regular litter are easily picked up and moved a few inches to help facilitate transfer to an ICU bed, OR table, or X-ray table, the LSTATs weight makes this task difficult, especially for shorter personnel.

The LSTAT system clearly has a place in the future care of critically ill and injured personnel in a field setting, be it a military or a civilian environment. Using the LSTAT in the austere and trauma-filled proving grounds of Kosovo has led to a much more detailed understanding of the LSTAT platform's capabilities and the need for modification in its role as a present and future battlefield patient-stabilization platform. With the improvements mentioned in this article, coupled with intense training of military medical personnel, the LSTAT will certainly be an invaluable tool in our primary mission in any future conflict, that of saving soldiers' lives.