MIRF: A Close Look at an IntensiveCare Aeromedical EvacuationCapability

LTC John C. Grant-Thomson'

It is a well-documentedfact that early intervention in the management of severe trauma cases improves recoveryrates. Organic to this capability is the need to provide highly mobile medical facilities equipped with appropriatemedical technologies. Dedicated medical platforms with onboard integrated medical systems, while desirablein some situations, are expensive and not always readily available in an emergency. Using a proven selectionof portable, electromedical monitoring and resuscitation equipment contained in one convenient module, theMobile Intensive Care Rescue Facility (MIRF) has been designed and developed to improve pre-hospital enroute medical care capabilities. Primarily designedforAeromedical Evacuation (AME) in the Australian DefenseForce (ADF), the MIRF provides a "stand-alone" life supportfacility which can "go anywhere" and attach toalmost any platform capable of carrying standard litters

Introduction

The exponentially increasing capital expenditurerequired to design and develop air and groundplatforms dedicated to provide critical care facilitiesduring transportation is significant.

A serious implication of customising road vehiclesor aircraft for intensive care emergency operation isthat inbuilt life support equipment tragically becomesunusable should the vehicle or aircraft becomeunserviceable. Further, should a transfer from onevehicle to another be required, the patient has to bedisconnected from these inbuilt life-support systemsto effect the transfer.

The MIRF

Designed by the author in the Faculty ofEngineering's Biomedical Engineering Unit at theUniversity of Southern Queensland, Toowoomba,Australia, MIRF is a technologically significantsolution to efficiently and effectively use currentlyavailable electromedical monitoring and resuscitationequipment in several scenarios.

Its design achieves compliance with current roadand aviation standards, particularly for structuralintegrity and electromagnetic compatibility.

It is the uniqueness and simplicity of the MIRFwhich makes it such an efficient and cost-effectivesystem for use in battle casualty situations, tacticaland strategic AME, and infield hospitals.

The Concept

The MIRF integrates patient, litter, and equipmentinto a single system. It is biomedically engineered toincorporate aeronautical, mechanical, electronic,electrical, and materials engineering into one highlymobile capsule.

The concept opens new horizons in rescue andtransportation strategies. The MIRF can be used as astand-alone system anywhere. It can be winched orparachuted into difficult rescue scenarios. It can becarried by ground personnel, placed in any vehicle,aircraft, or ship and most importantly, the patient canremain connected to its life-support systems from thetrauma point to the hospital, irrespective of the modeof transport.

The MIRF concept minimizes the need to purpose-build intensive care ambulances or aircraft. Existingtransportion can therefore be used, thus enhancing theservice, decreasing the response time, and reducingthe capital expenditure of modification andconstruction of specialist vehicles.

Description

The external profile of the MIRF has beendesigned to fit into a variety of aircraft and ambulance

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tLTC Grant-Thomson is a member of the Royal Australian Army MedicalCorps. He is the professor of Biomedical Engineering, University ofSouthern Queensland, Toowoomba, Queensland, Australia. He is also theAdvisor to the Surgeon of the Australian Defence Force and to the DirectorGeneral of Army Health Services.

vehicles. Its carrying handles have the samedimensions as the North Atlantic Treaty Organization(NATO) litter which means the MIRF can be loadedor unloaded in the same time and with the same easeas the NATO litter.

Several types of stretchers can be used on theMIRF including the current NATO litter. The medicalequipments, electronics, power, and oxygen systemsare contained in a lightweight carbon compositecapsule capable of withstanding the high inertial loadsimposed by military-and civilan aircraft designstandards. The capsule has a folding door which, whenopen, exposes the medical equipment and whenclosed, renders the MIRF dust- and shower-resistantand physically protects the medical equipment duringtransit. This allows the MIRF to be safely draggedacross the ground or lowered down cliffs. The carboncomposite casing also assists in shielding theequipment from receiving or emitting electromagneticradiation. Fold-away handles for manualtransportation are provided and the MIRF can evenbe carried on its side for enhanced maneuverability,such as encountered on ships.

Equipment

A comprehensive suite of medical monitoring andresuscitation equipment is contained in the MIRFcapsule. The equipment has been carefully selectedbased on its medical capability and suitability, sizeand weight, ability to withstand the environment, andits power requirements. Currently, this includes aninfusion pump, a syringe pump, and air/oxygenventilator, electrical suction, a multifunction monitor,and a defibrillator. In addition, the MIRF carries itsown oxygen and electrical power supplies.

Oxygen System

Two 440-liter capacity oxygen cylinders providingabout 1 1/2 hours of ventilation are included in theMIRF capsule. Mechanical ventilation is providedusing a transport ventilator connected permanently tothe oxygen bus. The infused volume and the breathingfrequency can easily be adjusted by the operator. Inaddition, an air/oxygen mix is provided where this isindicated. The output gas circuit of the ventilator isconstantly checked by an alarm monitor whichindicates either over pressure due to airway occlusionor under pressure due to a leaking airway. The upperand lower limits of these alarms are also operatoradjustable. A demand breathing facility plus an oxygentherapy capability is also available. If necessary, theoxygen supply can be replenished in transit while it is

being used by changing one cylinder at a time.Pressure gauges and low pressure alarms advise theoperator when to change a cylinder. External oxygencan also be connected at anytime if the host vehicle isso equipped.

Electrical System

The MIRF is fitted with a unique power supplywhich provides battery back-up and automatic batterycharging from a wide range of external power sources.These include:

* Any direct current supply between 1( and 40volts. This allows the MIRF to be powered frompartially discharged automobile batteries (normally12V) or aircraft (28V) power sources.

* Any alternating current supply such as theAmerican 120V, 60Hz system, or the Australian/European 250V, 50Hz system or aircraft 120V, 400Hzsystems. This provides the MIRF with an internationalpower supply system.

* In addition, the MIRF carries its own 12Ahsealed lead acid battery and charger which is used asauxiliary power to backup individual equipment.

Electromagnetic Compatibility

Some of the most challenging engineering workarose in attempting to have the MIRF certified to flyin civil and military aircraft. This meant compliancein all respects with Civil Aviation Authority AirNavigation Orders and American Militaryspecifications, particularly for structural andelectromagnetic compatibility aspects. Most countriesacknowledge the military specification known asMilitary Standard 461 defining limits for conduction,radiation, and susceptibility. The MIRF is certified ascomplaint with MIL-STD-461, civil aviation, andmilitary standards in Australia.

Military and civilian airworthiness requirementsin the areas of structural, composition, electrical andoxygen systems, fire resistance, safety equipment, andenvironmental conditions for the MIRF have also beenaddressed.

Operational Aspects

The MIRF underwent its first operational trialwhen the ADF committed a tri-service medical supportforce to Operation Tamar in support of the "UnitedNations Aid Mission In Rwanda" (UNAMIR II) from

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August 1994. Rwanda is a small, landlocked, andmountainous nation within central Africa. In April1994, a genocidal frenzy and subsequent civil war leftover half a million people dead and thousands injured.The Australian Medical Support Force (AUSMED)was tasked to provide a Level 3 resuscitation/surgicalcapability, limited humanitarian aid, and aeromedicalevacuation capability to UNAMIR II.

Rotary wing in-country tactical AME andinternational fixed wing strategic AME missions wereflown in a variety of airframes. These AME missionswere flown after initial ground and flight configurationtrinls A M1TRF mliintedl an ite trnllepvr wxithin thl-

LLCL1[O. · x l A 1\ & LNL J- LkJUIZ&~U VlI L ./3 L YYll[1 W IL ll. Ll, k,/

resuscitation area provided a convenient stand-alone Fig 2.platform from which all primary life supportintPr17vntinn rnrt mnnitnrTinr rarllr1 hok nrtrfnrrpml

Tactical AME missions involved the MIRF beingmoved by road with an AME team and secured withina Bell 412 helicopter with a standard NATO litter kit(Figure 1).

Fig 3.

casualty was placed onto the MIRF within theAUSMED facility and subsequently moved throughthe evacuation chain by road ambulance, then aircraft,

-pFig 1/. hand then road ambulance again to the destination"Fig A hospital (Figure 4).

At the retrieval destination, most priority twocasualties were lifed on NATO litters and placed ontothe pre-positioned MIRF. For casualties requiringventilation or stabilization, the MIRF was removedfrom the airframe, life support and monitoringestablished, and subsequently, the MIRF/casualtycombine refitted to the airframe (Figure 2).

Casualties transported in this manner frequentlyremained on the MIRF through the evacuation chainuntil final transfer onto an operating theater table atthe level 3 facility (Figure 3).

During inter-hospital strategic aeromedical…' - . . . . _1 _. _ ..' .-

evacuation or ventlatec, ntensive care patients, tne Fig 4.

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11

These 4- to 5-hour missions often required novelairframe and vehicle fits and highlighted the flexibleand convenient nature of the self-contained unit.Aircraft used were the Hercules C 130, Spanish CASA,and Russian Antonov AN26 (Figure 5).

Conclusion

The MIRF is a fully self-contained, mobile,airworthiness-certified, intensive care medical life-

support system rugged enough to meet both civilianand military requirements for emergency rescue andambulatory applications. It provides a stand-alone life-support system anywhere in the field, in a hospital,on the edge of an airstrip, in a tent, in an aircraft, roadvehicle, or even in the cabin of a ship. All of its leadsand sensors are contained in one highly mobile,module-connected ready-to-go at a moment's notice,which significantly improves emergency responsetimes.

The modular design of the MIRF with its flexiblepower and oxygen supply is a valuable asset in theconduct of both tactical and strategic AME missions.The carbon composite structure, proven in anoperational environment, houses reliableelectromedical components. It is concluded that inconcept and practice, the MIRF is an advanced,intensive care, aeromedical evacuation facility for useby Defense Forces in the management of highdependency casualties.

Reference

Gardner T. "Operational Evaluation of the MIRF." February 12, 1995.Fig 5.

26 Army Medical Department Journal