Since the earliest days of horse-drawn and motorized ambulances, the capability to transport multiple non-ambulatory patients in each vehicle was seen as essential. The Model T field ambulances of World War I carried three to four litter (non-ambulatory) patients – depending on model. So important was this feature seen, that in one of the first references to “emergency medical services,” the Office of Civilian Defense recommended civilian ambulances with only two litter capability be field modified with plywood to obtain “four litter” capability.1 The military’s “field-litter ambulances” bring this “four-litter” capability to the battlefield into the modern day.2
Many ambulance personnel in the 1950s-1970s had combat experience in World War II, Korea, and/or Vietnam. It is perhaps not surprising that many early ambulances also had multiple patient capability. Contemporary ambulance crews understood the concerns of disaster planning, as Civil Defense programs of the time emphasized catastrophic disasters, particularly enemy attack.3 In addition, prior to the developments that followed Emergency Medical Services Systems Act of 1973 – rural locations in particular might only have one or two ambulances in an area. Law enforcement or fire service co-response to motor vehicle collisions and medical emergencies would often be inconsistent at best.
A two-vehicle collision in an era without airbags, “crumple zones,” or even consistent seatbelt usage could easily result in multiple, critically injured patients. Ambulance crews of that era would elect to transport multiple patients in one vehicle, rather than abandon patients on the scene. Thus, well into the 1980s – a “top of the line” professional car, van, or truck chassis ambulance would be expected to have “four-litter” capability – one patient on the standard ambulance cot, one backboard or folding stretcher on the squad bench, and two folding stretchers hanging from the ceiling.
One high-end ambulance manufacturer – the Hess & Eisenhardt Company (also makers of presidential limousines) proudly advertised the potential for a fifth litter patient to fit on the floor between the main ambulance cot and the squad bench (Figure 1).
As the 1980s progressed, ambulance services expanded coverage and increased the number of in-service units on the street. It became possible in many areas to dispatch multiple ambulances to calls with the potential multiple patients, with the safety factor of law enforcement or fire service “first response” to many scenes. With the ever-increasing focus on the sophistication of care that could be provided to a single patient – multiple patient capability (particularly “hanging hardware”) within ambulances became less and less common as a feature.
The most recent General Services Administration (GSA) KKK-A-1822 specifications list an ambulance as including a “patient compartment to accommodate an emergency medical services provider (EMSP) and one patient located on the primary cot so positioned that the primary patient can be given intensive life-support during transit,” but it does not define multiple patient capabilities as a requirement or even a listed option.4
The military and some other federal agencies maintain the “four-litter” option for the GSA-specification (civilian-type) ambulance (Figure 2) Acadian Ambulance Service, one of the largest private ambulance companies with a predominantly rural service area, includes “hanging hardware” in all ambulances (the smaller Mercedes Sprinter Type II ambulances in the Acadian fleet are only capable of carrying a third patient.) Both Acadian and the military recognize the potential for disaster/mass casualty response that is brought to the scene by a “four-litter” capable ambulance.
Acadian leadership understands that resources within rural locations are limited with little opportunity for rapid arrival of additional support. While not advocated for routine use, the criteria for a mass-casualty incident depend heavily on the resources available immediately on-site. The military environment in a combat or deployment environment presents obvious benefits to multiple patient transport capability. However, the rural environment familiar to Acadian and other rural ambulance systems is also found on military installations within the United States, with expansive training areas and finite ambulance resources. Due to this, the Army EMS Program Office specifies “four-litter” capability within all non-tactical Army ambulances in the most recent specification package.
Perhaps the greatest argument for ambulance multiple patient transport capability is the ever-present specter of mass shootings, bombings, and other acts of terrorist violence. “Secondary devices” intended to target emergency personnel are well known risks of bombings. There may be additional violent actors waiting for the response, particularly in coordinated acts. It is therefore essential for not only patient care, but also patient and responder safety to evacuate from the active scene as soon as possible.
“Four-litter” capability may be one means by which to more rapidly evacuate patients from the scene of these congested incidents by increasing the patient transport capability of each responding ambulance. The recent events of 2012 Aurora, Colorado, shooting and the 2016 Las Vegas, Nevada, shootings demonstrated the utility of rapid multiple patient transport by non-ambulance vehicles.5
The primary modification of an ambulance to allow “four-litter” capability is hardware installed in the ceiling and side interior of the patient compartment. The “traditional” hardware (manufactured by Cast Products, among other manufacturers) is relatively low priced in comparison to other optional features. However, there is anecdotal, poorly documented concern about the crashworthiness of these “traditional” products. To the authors’ best research, there has been no documented ambulance accidents involving “hanging hardware” in use.
Further, it is presumed that usage of such a feature’s use would be rare – only in significant emergencies where the assessment has already been made that either patient or responder safety would be compromised by delay in transport. If concern persists, Ferno-Washington (among other manufacturers) make impact-resistant folding litter stanchions (similar to that seen on military aircraft) at a greater cost. Each ambulance must carry at least two folding litters/stretchers capable of being placed in the “hanging” positions in order to utilize these patient positions.
Technique with use of “hanging hardware” is important. It can be difficult for a small crew to load even a lightweight patient into an ambulance, and then lift him or her to the ceiling. The most efficient loading procedure is to utilize the main ambulance cot to load the first patient into the ambulance. They are transferred to hanging hardware over the squad bench. The second patient is loaded onto the squad bench in the same manner. The third patient is loaded into the ambulance using the cot, the crew then raises the cot to place the patient into the hanging hardware with a minimum of lifting. The last patient remains on the ambulance cot. It goes without saying that the lightest patients should be selected for “hanging-litter” positions and must be on folding litters/stretchers capable of being in these positions.
Monitoring and aggressive, advanced-patient care will be limited in an ambulance loaded with four critical patients. More recently, wireless monitoring techniques have been developed to allow serial monitoring of multiple patients simultaneously.6 As traumatic mechanisms such as mass shootings and bombings are the most likely reason crews would utilize this capability, it would be optimal for personnel to apply immediate life-saving interventions such as tourniquets, chest seals, and simple airways in accordance with Tactical Emergency Casualty Care guidelines prior to loading the patient into the ambulance at the Casualty Collection Point.
In brief, “four-litter” capability may provide a low-cost improvement in patient care by effecting rapid transport from a scene where care resources are inadequate. Additionally, it may support responder safety by allowing more rapid evacuation of patients from the scene of mass violence with fewer crews exposed in an era when emergency services personnel remain targets.
Drs. Nicholas M. Studer, William R. Smith, Jason R. Pickett and Cord W. Cunningham are servicemembers in the United States Army. Dr. Chuck Burnell is employed by Acadian Ambulance Service. The authors have no financial interest in, nor receive payments from, any medical device manufacturers or distributors.
The views expressed herein are those of the author and do not reflect the official policy or position of the U.S. Army Medical Department, the U.S. Army Office of the Surgeon General, the Department of the Army and Department of Defense, or the U.S. Government. Use of trade or brand names in this publication is for illustrative purposes only and does not imply endorsement by the Department of Defense.
- Office of Civilian Defense. Field Care and Transportation of the Injured: a Manual for the Training of Rescue Workers, Medical Auxiliaries, Ambulance Drivers, and Attendants and Stretcher Bearers. Washington, DC: Government Printing Office; 1943.
- United States Army. FM 4-02.2: Medical Evacuation. Washington, DC: Government Printing Office; 2007.
- Federal Civil Defense Administration. Emergency Medical Treatment. Washington, DC: Government Printing Office, 1953.
- General Services Administration. KKK-A-1822F: Federal Specification for the Star-of-Life Ambulance. Washington, DC: Government Printing Office, 2007.
- Reeping, PM, Jacoby, S, Rajan, S, Branas, CC. Rapid response to mass shootings: A review and recommendations. Criminol Public Policy. 2020; 19: 295– 315. https://doi.org/10.1111/1745-9133.12479
- Van Haren RM, Thorson CM, Valle EJ, et al. Novel prehospital monitor with injury acuity alarm to identify trauma patients who require lifesaving intervention. J Trauma Acute Care Surg. 2014;76(3):743-749. doi:10.1097/TA.0000000000000099