Tactical ultrasound is the use of ultrasound to guide ...



Title: Military and Tactical Ultrasound

Authors:

Robinson M Ferre, MD, FACEP, Maj (USAFR)

Director, Emergency Ultrasound

Department of Emergency Medicine

Vanderbilt University Medical Center

Nashville, TN

Jeremy Johnson, MD, Maj (USA)

Emergency Ultrasound Fellowship Director

Department of Emergency Medicine

Darnall Army Medical Center

Fort Hood, TX

Brian Hall, MD, RDMS, Maj (USA)

Director, Emergency Ultrasound

Department of Emergency Medicine

Darnall Army Medical Center

Fort Hood, TX

Todd Peterson, MD RDMS, Maj (USA)

Department of Emergency Medicine

Darnall Army Medical Center

Fort Hood, TX

Bill Heegard, MD, FACEP

EMS Director

Department of Emergency Medicine

Hennepin County Medical Center

Minneapolis, MN

Michelle Mendoza, MD, RDMS

Department of Emergency Medicine

University of Massachusetts Medical Center

Springfield, MA

Mary-Elise Manuell, MD, MA, FACEP

Director, Division of Disaster Medicine and Emergency Management

Department of Emergency Medicine

University of Massachusetts Medical Center

Springfield, MA

Brooks LaSalle, MD, RDMS, Maj (USA)

Emergency Ultrasound Fellowship Director

Department of Emergency Medicine

Madigan Army Medical Center

Joint Base Lewis-McChord, WA

Shane Summers, MD, RDMS, Capt (USA)

Director, Emergency Ultrasound

Department of Emergency Medicine

Brooks Army Medical Center

Fort Sam Houston, TX

Bradley Youngren, MD, FACEP, Maj (USA)

Emergency Ultrasound Director

Department of Emergency Medicine

Madigan Army Medical Center

Joint Base Lewis-McChord WA

Introduction:

A Brief History of Military Emergency Ultrasound in the United States:

The current wars in Iraq and Afghanistan are the first prolonged conflicts to include physicians trained in emergency medicine. While the first gulf war in 1991 utilized emergency physicians (EP), the entire ground assault lasted less than a month and a mature multi-service medical system was never established.1 Today, EPs play a key role in the combat environment because of their unique training in the initial evaluation and resuscitation of critically ill and traumatically injured patients. The unique skill set of EP, includes the use of emergency ultrasound (EUS). Since the first gulf war in 1991, EUS has become a mandatory component of emergency medicine residency training, emergency ultrasound fellowship programs abound and EUS has come to play a vital role in the evaluation of patients by EPs. 2-13

Utilized by both surgeons and EPs, EUS in trauma was quickly embraced by the military. In order for this technology to be useful on the battlefield, a small hand-held ultrasound device that was light, portable, durable and battery powered needed to be developed. In 1996, the Defense Advanced Research Projects Agency (DARPA) approached Advanced Technology Laboratories in hopes that they would develop this technology. In less than a year, a new company was formed that eventually created this new portable ultrasound platform.14 The new company, SonoSite corporation, introduced the SonoSite 180 in 1999, the first portable, durable, light-weight, battery-powered ultrasound system.15 It soon became standard issue in all forward deployed trauma team assets in the Army, Air Force and Navy.

As EP gained more experience with EUS, additional examinations beyond the focused assessment with sonography in trauma (FAST) were added to the scope of practice. In 2001, ACEP published their first guidelines for emergency ultrasound use by EP. These guidelines described the practice of EUS, the type of examinations that were considered fundamental, and recommended training pathways for competence in EUS.15 In 2008, these guidelines were updated to reflect the increased use and scope of EUS in caring for patients in emergency medicine.16 EPs practicing in the military have taken these skills in EUS and have utilized them in the austere environment of battlefield medicine. EPs are able to use EUS to assist in the diagnosis, treatment and disposition of soldiers, sailors, airmen and marines as well as civilians and enemy combatants that present with injuries or illnesses sustained while in the theater of combat operations.18-21

Tactical Ultrasound Defined:

EP who are deployed to the battlefield, find themselves in an environment that is distinctly different from the typical hospital-based emergency department in the United States. Resources, including diagnostic tests, medicines and personnel are extremely limited. In many cases, medical equipment is limited to what can fit inside 2-3 large backpacks. Because of its size and utility, hand held ultrasound is one of only a few diagnostic modalities allocated to EP in far forward deployed locations. Because it is often the only diagnostic imaging modality and one of a few total diagnostic tools beyond a stethoscope and physical exam, it is used to full advantage in making important diagnostic, treatment and disposition decisions.

In this paper we describe the use of emergency ultrasound in austere environments to guide tactical decision-making. We describe the use of tactical ultrasound, which is the use of emergency ultrasound to guide decision-making in the diagnosis, treatment and disposition of patients when resources are scarce and testing is severely limited. It is the use of emergency ultrasound in an environment that is inherently different than routine daily practice in emergency departments in the developed world; where utilization of limited resources necessitates a comprehensive evaluation of risk to the patient, individuals involved in their care and/or other patients competing for care. Tactical ultrasound provides critical information that justifies the utilization of limited resources and the significant risk involved in mobilizing a patient to higher levels of care. Battlefield medicine is the primary venue where tactical ultrasound is useful, however, these same principles apply to civilian mass casualty incidents, extreme and isolated environments and in rural pre-hospital settings.

The Combat Environment and The Military Medical System:

In order to understand the utility of tactical ultrasound it is important to understand the battlefield environment, the military medical system and combat medicine. The purpose of combat medicine is to return the greatest number of military members to combat and to preserve life, limb and eyesight in those who must be evacuated from the battlefield.22 The treatment, disposition and transport of patients within or out of the theater of combat operations is a tactical decision. Injuries and illnesses in a combat zone present to a military treatment facility (MTF) that has limited diagnostic and treatment resources. Many patients will require transport to higher levels of care for additional diagnostic tests, procedures and treatment. However, movement of ill or injured combat troops requires manpower, use of limited resources and risk of injury and death to those involved in transporting the patient. In addition, the decision to remove a military member involved in combat operations is not only a loss of manpower, but may also involve losing a member with unique and critical skill sets that may be imperative to successfully completing the current mission. Therefore, the decision to remove a member from their combat position is complicated not only by their current medical condition but by their current role in the combat mission and the logistics of moving them within the battlefield environment. The loss of manpower, especially those in critical roles, may result in the failure to accomplish the military objective, which may result in the further loss of life and resources. Thus, any information that can be gleaned as close to the initial point of injury is critical in accomplishing the mission, conserving resources, preserving the fighting force and minimizing risk and utilization of fixed resources.

The military medical system is designed to preserve the fighting force while maintaining the necessary mobility and agility needed to accomplish the military objective. In order to do this, medical assets are deployed in a tiered manner, with limited medical resources on the front line and greater resources in strategically located areas on and off the battlefield. Napoleon is credited with being the first military leader to organize medical care of ill and injured troops in this tiered manner.23 In the United States military today, a comprehensive tiered system of medical care ranges from the front lines to large medical centers in the United States.22-24 These different levels of care are described as levels or echelons of care.

Echelons of care

Echelons of care and evacuation have traditionally been structured to follow battle lines, which through the first 200 years of armed conflict involving the United States, were predominantly linear battles up to and involving the first war in Iraq, Operation Desert Storm.

Today’s military medical system incorporates five echelons, or levels, of care that begin with the point of wounding, injury or illness and extend through the eventual evacuation and treatment in fixed United States (CONUS) facilities (see table 1). Each succeeding echelon builds upon the abilities of the previous by adding a new increment of treatment capability. Within a theater of combat operations, the first four echelons of medical support are characterized by increasing levels of medical sophistication, hold over times as well as the number and access of medical and aeromedical assets.

Table 1 Military Medical System Levels of Medical Care

|Level |Unit Level |Medical Unit/Personnel |Care |

|I |Team |Self aid/Buddy aid |Basic first aid |

| |Squad |Combat lifesaver |Initial emergency treatment |

| |Platoon |Combat Medic |Initial stabilization and resuscitation |

| |Company/Battalion |Battalion Aid Station | |

|II |Division |Medical Company |Medical management and stabilization |

| | |FST | |

| | |MFST |Life saving resuscitation and surgery |

| | |Expeditionary Medical Unit | |

|III/IV |Corps/Theater |CSH, Theater Hosptial, USS MERCY, USS |Comprehensive |

| | |COMFORT |Resuscitation and Surgery |

|V |Continental US |MEDCEN |Definitive Care and Rehabilitation |

Level I

The first echelon of care is the most austere, far forward and lowest level of care in the medical evacuation (MEDEVAC) system. It has 4 internal levels of increasing complexity and care. At the soldier level, it is made up of self and buddy aid provided by soldiers applying dressings, tourniquets and providing emergency aid. The individual soldier is followed by the combat lifesaver, at the squad and team level, that has been trained to provide limited advanced first-aid. The first medically trained soldiers on the battlefield are Army Combat Medics, the Navy Corpsman and the Air Force Medical Technician who can provide limited emergency medical treatment, intravenous therapy and some lifesaving airway maneuvers. These military members typically serve alongside combat teams.

The battalion aid station is the highest level of care within echelon I and is the first medical facility available to the wounded. These facilities are mobile units and care is often provided from a temporary building, the back of a tracked vehicle, Stryker or Humvee Ambulance. The battalion aid station is generally staffed by a physician, a PA and one or two medics. The doctor and PA can either be co-located or separated within their area of operation to provide broader coverage. Care provided includes advanced triage, non-surgical life and limb saving trauma management, airway and resuscitative care needed prior to evacuation to a level II or level III facility.

a. Level II

The second echelon of care is provided at a predominantly fixed, but mobile capable medical facility staffed by a team of physicians, nurses, supporting technical and medic staff that is referred to as the Expeditionary Medical Unit in the Air Force and traditionally the area support medical company in the Army. Military members are examined to determine the level of care that is needed and precedence for evacuation. If appropriate, wounded warriors are treated and returned to their duty station.

Each facility has the ability to perform acute trauma resuscitation and stabilization and most include basic laboratory, pharmacy, x-ray, and dental capabilities as well. Often, second echelon units are able to hold patients for up to 72 hours and may be able to administer group O blood transfusions. Beginning with Operation Enduring Freedom the forward placement of advanced surgical teams (MFST, FST, STP) has been used with increasing frequency and efficiency resulting in improved survivability in previously lethal trauma. Care focuses upon emergency procedures and operations to stop life-threatening hemorrhage, prevent probable death or loss of limb; however, treatment is generally limited to measures necessary for immediate stabilization.

b. Echelon III

Third echelon facilities are the first truly fixed facilities that a wounded military member will encounter in theater. These are facilities, while designed to be mobile, have a large footprint and have a limited ability for deployment or redeployment once established in a theater of operation. Once in theater, they will often occupy an amalgamation of portable units and hardened structures. Examples include current facilities located in Balad, Iraq, and Bagram, Afghanistan. These facilities retain the capabilities to hold patients for extended periods of time and they provide the first step toward restoration of functional health. They are staffed by advanced medical and surgical specialties to include critical care and subspecialty surgical services and generally have the ability to perform advanced preoperative diagnostic procedures, intensive surgical procedures, and postoperative care. In addition to the medical and surgical capabilities, a relatively wide range of blood products are available including whole blood, packed cells, fresh frozen plasma, platelets, and specialty coagulation. Typical third echelon facilities are the deployable medical system (DEPMEDS) hospitals used by all services and the Navy’s hospital ships.

c. Echelon IV

Fourth echelon care has traditionally been extensive fixed general, theater or permanent station hospitals that provide relatively the same care given at level III facilities but were designed with the intent to accept, treat and rehabilitate soldiers in theater before returning them back to their units. With respect to the current global mission, there are no such acting facilities. Landstuhl, Germany while not in theater is currently the closest such facility being used in the treatment of battlefield casualties outside of the continental US.

d. Echelon V

Fifth echelon care is provided by fixed Medical Centers (MEDCEN) and Military Treatment Facilities (MTF) located in the continental US. Current guidelines stipulate that soldiers are to be sent to Walter Reed Army Hospital for certain definitive specialty and subspecialty care, and rehabilitation, then transferred to the MTF nearest their home unit or home of record.

Ultrasound Applications on the Battlefield:

The complete scope of emergency ultrasound is utilized on the battlefield. Tactical ultrasound, performed by EP, is used in the assessment of combat related injuries, non-combat related trauma and medical illnesses in deployed military members, enemy combatants and civilians presenting to military treatment facilities. In addition, tactical ultrasound can be used to provide procedural guidance and assess the on-going resuscitation of critically ill patients. While these tactical ultrasound examinations and procedures are part of the training and scope of emergency medicine practice, the application and disposition decisions from these ultrasound examinations may be different given the current battlefield conditions, operations tempo and facility in which the EP is practicing.13, 17

In level 1 and many level 2 facilities, tactical ultrasound is the only imaging modality that is available. Furthermore, formal ultrasound studies performed by licensed sonographers and radiologists are not available. Table 2 lists tactical ultrasound examinations performed by EPs in forward deployed environments to assist in the diagnosis and disposition of ill or injured military and civilian patients. The utility of these examinations may differ based upon the diagnostic and treatment resources available. Table 3 lists the utility of these examinations based upon the echelon of care the EP is performing the examination. The more common and important applications are discussed below.

TRAUMA

The FAST Examination:

The Focused Assessment with Sonography in Trauma (FAST) examination is a core component of the evaluation of military and civilian casualties on the battlefield. It is performed following the primary survey to evaluate for free fluid in the abdomen, chest and pericardium.11,21,25-26 On the battlefield, it is the first-line imaging modality used to assess for intra-thoracic and intra-abdominal traumatic injury. It provides critical information to guide triage, treatment and evacuation decisions. It has completely replaced DPL in the deployed military settings, and has been shown to be faster and safer to perform.27

The basic views of the FAST exam include the upper right and left abdomen, cardiac and pelvic views. These four views allow for visualization of free fluid in the main collection areas of the abdomen, chest and pericardium. Ultrasound is a sensitive and specific marker for free fluid in the chest, pericardium and peritoneum, especially in patients who are hypotensive.25-26 The FAST examination, in conjunction with the patient’s clinical status, is extremely useful in triaging patients on the battlefield with blunt, penetrating and blast injuries to the operating room for further surgical evaluation and treatment. This is especially true in battlefield casualties with injuries due to improvised explosive devices (IED) as they frequently have a combination of blast, blunt and penetrating injuries. These patients are often covered with small penetrating fragment injuries and frequently have traumatic amputations. They are often hypotensive as a result of bleeding from a variety of sources including traumatic amputations and concurrent intra-abdominal solid organ and vessel injuries. In these patients, the FAST exam is crucial as a triage tool as hemorrhage only from extremity amputations can be controlled with the use of a tourniquet and operative intervention can be delayed if needed until the patient has been adequately resuscitated or until other casualties with intra-thoracic or intra-abdominal bleeding are out of the operating suite. Evidence of pericardial hemorrhage and intra-abdominal hemorrhage requires immediate surgical correction. However, patients without evidence of intra-abdominal hemorrhage or pericardial effusion can be resuscitated in the resuscitation area before operative intervention given the increased use of tourniquets for devastating extremity injuries.

The EFAST Examination:

The extended FAST exam, or EFAST, adds evaluation of the lung fields to detect pneumothorax (PTX) to the traditional FAST exam. This exam is performed by using a linear or curved probe in a longitudinal position, scanning the anterior surface of the chest from the clavicle to the diaphragm. Evaluating between rib spaces, the motion of the lung moving against the chest wall is visible in a normal study. The motion of the visceral pleura sliding against the parietal pleura in the absence of a PTX, also known “lung sliding” is seen with b-mode imaging. Color flow Doppler and m-mode imaging may be used to assist with detection of lung sliding. If lung sliding is absent, the patient has sonographic evidence of a PTX. In many military settings x-ray is not available, and using the ultrasound to detect a PTX and size assists in management and disposition of the patient. Thoracic ultrasound to diagnose pneumothoraces is more sensitive than chest x-ray and can detect small PTXs that are less than 1% of thoracic volume.28-29 These small PTX, which may not be detectable on chest x-ray, are important to diagnose and require tube thoracostomy drainage if being AEROVAC out of theater. A PTX may increase as much as 4 times in size from sea-level to 8000 ft, which is the cabin pressure for most fixed wing flights out of theater.22

Musculoskeletal and Soft Tissue Examination:

Many battlefield casualties, especially in the early part of a military operation, will present to a level 1 facility that does not have x-ray capability. Many will have fractures from high impact mechanisms, as seen with IED’s. These injuries are often obvious and can be further evaluated as the patient is transferred to higher levels of care. However, more orthopedic injuries are the result of routine daily duties and are not obvious without x-rays. In these cases when x-ray is not available, the military members effectiveness and fitness for duty may be compromised until definitive diagnosis is clear.

Ultrasound has been successfully used as a screening tool to exclude long bone fractures at many level 1 settings.19 Ultrasound is inferior to x-ray to detect fracture, however, the ability to use ultrasound in conjunction with clinical presentation to risk stratify deployed military members presenting with minor orthopedic trauma, is an effective tool that is used on a daily basis at far forward deployed locations.

Ultrasound detection of foreign bodies (FB) is well documented, and varies depending on the users skill level and the type of FB being detected.28-29 In battlefield setting, most cases involve metallic FB, which show acoustic shadowing and reverberation artifact on ultrasound. In addition to detection, FB removal, if necessary, is greatly improved with US guidance.32

Ocular Examination:

Both traumatic and non-traumatic ocular complaints are common on the battlefield. EUS is useful for the detection of traumatic or non-traumatic lens, retinal and vitreous detachments. In these cases, a high-frequency linear probe is rested gently above the patient’s eye, and the globe is examined in longitudinal and transverse planes looking for hemorrhage, foreign body or retinal detachment within the globe.33-34

Ocular ultrasound is also useful and is gaining acceptance as a screening tool for elevated intracranial pressure (ICP) and the need for neurosurgical intervention. Because access to CT scanning is severely limited and direct measurement of ICP requires an invasive procedure, ultrasound can be used as sensitive and non-invasive screening tool at far forward locations especially as closed head injuries have become a very common injury with the use of IEDs in Iraq and Afghanistan. This is exam is performed by measuring the diameter of the optic nerve sheath 3mm posterior to the retina. An optic nerve sheath measurement greater than 5mm in adults is concerning for and predictive of intracranial injury.5, 35

Resuscitation Evaluation:

Intravascular volume status may be estimated by measuring the diameter of the inferior vena cava (IVC) just below the diaphragm. IVC diameter measurement can be performed as an adjunct to the FAST exam and can help during the resuscitation and evaluation phase of battlefield casualties. This can be a helpful tool in triaging patients with evidence of intraperitoneal bleeding on FAST exam. Many young healthy military members have a large cardiovascular reserve and may be more severely volume depleted than their initial vital signs may suggest. The IVC diameter gives a more direct estimation of total volume status and can help determine those needing more emergent surgical control of intra-peritoneal or intra-thoracic bleeding. In addition, IVC measurement may be used to estimate volume status before and during fluid resuscitation and can guide further fluid management decisions.

The IVC diameter is measured 2 cm below the junction of the right atrium. The IVC diameter is greatest during end expiration and should be measured accordingly. The IVC collapsibility index should also be calculated by measuring the IVC diameter at end inspiration and by dividing by the IVC diameter at end expiration (IVC collapsibility index = IVC diameter end inspiration/ IVC diameter end expiration). Small initial IVC diameter and near or complete collapse of the IVC with respiration correlates to low intravascular volume and the need for administration of colloids or cystalloids.36-37

MEDICAL

Battlefield medicine encompasses not only trauma, but also evaluation for routine medical complaints and conditions. Accurate diagnosis of non-combat related medical conditions at forward positions (i.e. level 1 and 2 facilities) is essential to preserving health and fixed resources such as military aircraft, fuel and personnel. Tactical ultrasound is a key tool that enables EP to maintain the fighting force and keep assets in a position where they can best accomplish their mission.

Biliary Examination:

Non-traumatic abdominal pain is a common complaint among deployed military members. In patients who present with epigastric pain or tenderness, evaluation of the gallbladder and common bile duct can easily be accomplished with ultrasound. Emergency physicians evaluate for the presence of gallstones, thickened gallbladder wall, pericholecystic fluid and/or a sonographic Murphy’s sign. The presence of gallstones and a sonographic Murphy’s sign has a very high (>90%) positive predictive value for acute cholecystitis.33 However, the presence of a thickened gallbladder wall and pericholecytic fluid further improves the specificity and positive predictive value.33

Renal Examination:

The prevalence of kidney stones is high among active duty troops deployed to hot desert climates. Diagnosis and disposition of military members presenting with flank pain can be guided with a urinalysis and renal ultrasound. The major complications of ureteral stones requiring evacuation are infection, continued pain and severe ureteral obstruction. The presence of hydronephrosis in a patient presenting with flank pain is indicative of ureterolithiasis. Patients with trace to mild hydronephrosis can usually be managed without the need for MEDEVAC. However, patients who demonstrate more than mild hydronephrosis are more likely to have complications and should be referred to a higher echelon of care for treatment.

Upper and Lower Extremity Deep Vein Examination:

Deployed military members, especially combat casualties, are subject to long transportation times that can be several days long. This places them at increased risk for developing deep venous thrombosis (DVT). Physical exam findings for DVT are often vague and unreliable and a d-dimer test is not available at level 1 or 2 facilities. Emergency ultrasound is sensitive and specific for determining the presence or absence of DVT.38-39 Diagnosis is essential to prevent pulmonary embolism. Military members requiring anticoagulation are not suitable for duty in the combat theater and must be sent back to their home duty station for treatment.

Soft Tissue Examination:

The primary soft tissue application is differentiating an abscess versus cellulitis. Due to heat, close proximity and shared facilities skin infections are very common in deployed military members. Emergency ultrasound is useful in helping to differentiate between cellulitis and abscess and helps guide the physician in planning for best location for the incision and drainage.40

First Trimester Pregnancy Examination:

With close living arrangements and long deployments, it is not uncommon for female military members to become pregnant in theater. All pregnant soldiers must be evacuated and returned to their home duty station. Detection of first trimester pregnancy is essential in this process, and also essential in evaluating female patients with abdominal pain, hypotension, or syncope. Endocavitary probes are not part of the standard equipment allowance for ultrasound machines at level 1 or 2 facilities, however transabdominal scanning can be used for evaluation of intra-uterine pregnancy or free fluid in cases of ruptured ectopic pregnancy.

PROCEDURAL

Venous Access Guidance:

Central line placement under ultrasound guidance has shown to be more efficient and safer in traditional hospital settings. This does not change in the deployed environment. Given improved access with ultrasound, it is common that ultrasound is used in placing Internal Jugular, Femoral, Supraclavicular, Subclavian, and even arterial lines.41

Peri-tonsillar Abscess Examination and Guidance:

Detection of PTA is easily performed with an endocavitary probe, and may replace CT scan in a deployed setting when CT is not available. In cases when a PTA is detected, it may be drained using real time guidance.42 In situations when real time guidance is inhibited due to a lack of space in the oral cavity, the carotid artery can be located with ultrasound in reference to the abscess, and the distance measured. The distal tip of the needle guard may then be cut to create a safety measure ensuring the needle is not inserted too deeply and puncturing the carotid artery.

Nerve Block Guidance:

Extremity trauma, including traumatic amputations are common with IEDs. While an advanced procedure, ultrasound-guided peripheral nerve blocks to including, Femoral, Popliteal, Radial, Ulnar and Median nerve blocks can be used with great success in the tactical and austere environments. They are surprisingly easy to perform and require limited medical resources. In situations involving a small force where every soldier’s tactical presence is important, a soldier with an extremity injury that has been given narcotic medications is no longer an active tactical participant. Instead, an US guided block can be used resulting in a lucid engaged member of the team. During prolonged extractions and evacuations, US guided peripheral nerve blocks can improve patient comfort and decrease narcotics needed for pain control.

|Trauma |EFAST (hemoperitoneum, hemopericardium, hemothorax, pneumothorax) |

| |Foreign Body Detection (soft tissues, ocular) |

| |Long Bone Fracture |

| |Tendon Rupture |

| |Resuscitation |

|Medical |Gallbladder and Biliary Tract |

| |Echo |

| |Renal |

| |First Trimester Pregnancy |

| |Abdominal Aorta |

| |Extremity Deep Vein |

| |Ocular |

| |Soft Tissue |

|Procedural Guidance |Central and Peripheral IV Access |

| |Nerve Blocks |

| |Abscess Drainage |

| |Foreign Body Removal |

| |Arthrocentesis |

| |Thoracentesis |

| |Lumbar Puncture |

Table 2. Types of Emergency Bedside Ultrasound Examinations Performed on the Battlefield

|Exam |Degree of Utility |

| |Level 1 |Level 2 |Level 3 |

|EFAST |High |High |High |

|Resuscitation |High |High |High |

|Musculoskeletal (Long Bone Fracture) |High |Moderate |Low |

|Musculoskeletal (Foreign Body) |High |High |High |

|Echocardiography |High |High |High |

|First Trimester Pregnancy |High |High |High |

|Renal |High |High |Moderate |

|Extremity Deep Veins |High |High |High |

|Ocular |High |High |High |

|Abdominal Aorta |High |High |High |

|Soft Tissue (cellulitis vs abscess) |High |High |High |

|Gallbladder |High |High |High |

Table 3. Utility of Tactical Ultrasound Examination Based on Echelon of Care

Tactical Ultrasound as a Disposition Tool

Far Forward Deployed Settings with Level 1 Medical Assets:

Treatment and disposition decisions are affected by a variety of factors on the battlefield. For routine medical and non-combat trauma, these decisions entail not only a military members ability to perform their combat role, but the risks their condition has on their ability to survive in a hostile environment. This is particularly true in far forward settings where servicemen are engaged in day-to-day combat operations. Non-combat related orthopedic injuries are a major cause of loss of personnel to the fighting force with routine MEDEVAC to higher levels of care for further evaluation and treatment. For this reason, almost 90% of MEDEVACs are for non-combat related injuries and conditions. Tactical ultrasound has proved valuable in evaluating non-combat related orthopedic trauma by excluding long bone fractures of the arms and legs. A negative soft tissue ultrasound in combination with a short course of observation can rapidly exclude fracture and return soldiers to duty faster than MEDEVAC to a level 2 or 3 facility with x-ray capability.

Other routine complaints such as flank pain and right upper quadrant abdominal pain, can also combine ultrasound and a short observation course for exclusion of acute pathology that would need surgical intervention or require MEDEVAC out of the theater of operations.

Level 1 facilities do not have the capability of treating surgical trauma. However, tactical ultrasound is key in arranging disposition and triaging wounded casualties to higher levels of care. EFAST with IVC diameter measurement can find those military members with the greatest need of surgical intervention and arrange for their evacuation first. This is especially true in cases where air assets have been grounded due to weather conditions and casualties must be transported by ground in hostile conditions.

Forward Settings with Level 2 Medical Assets

Level 2 facilities have limited surgical and x-ray capability. Battlefield casualties can present in groups that can quickly overwhelm and deplete surgical resources. Tactical ultrasound is helpful in these settings by identifying those with need for emergent surgical control of bleeding. Because many combat injuries are due to IED blasts, patients often have a combination of blast, blunt and penetrating injuries. It can be challenging on physical exam to determine the exact etiology of a patients hypotension, especially in patients with traumatic extremity amputations. The EFAST exam is crucial in identifying PTXs and bleeding in the abdomen, pleural or pericardial spaces. Patients with intra-abdominal bleeding or bleeding into the pericardial sac need emergent surgical intervention, while those hypotensive solely due to extremity injuries can be resuscitated first and be delayed until the more seriously injured are out of the operating suite.

Because battlefield injuries often occur with multiple casualties simultaneously, a level 2 facility may quickly be overwhelmed with patients needing emergent surgical intervention. In these mass casualty events, tactical ultrasound plays a crucial role in triaging patients to the operating suite. Combat casualties that are hypotensive, have large amounts of intraperitoneal free fluid, have a collapsible IVC or pericardial fluid require immediate surgical intervention. However, patients who have a positive FAST exam who are normotensive, have a non-collapsible IVC and have only small amounts free fluid seen on FAST exam may and who are waiting for operating suite availability, may receive faster surgical care by being sent to other level 2 or 3 facilities. Repeat EFAST examinations and IVC diameter measurement can be valuable in continuously re-triaging of casualties as operating suites become available.

Forward Settings with Level 3 Medical Assets

Level 3 facilities have much greater resources and are capable of operating on many patients simultaneously. In addition, most level 3 facilities have CT capability and do a more non-invasive evaluation for injury, including intracranial hemorrhage. However, because of their size and the availability rotary wing aircraft, level 3 facilities can often see up to 20 combat casualties present in less than an hour with the vast majority needing surgical intervention. Tactical ultrasound plays a key role in triaging patients to the operating room or to CT and provides a mean of rapid continuous evaluation of those waiting surgical intervention. Serial FAST examinations and hemodynamic response to resuscitation results in the continuous re-evaluation and re-triaging of patients awaiting operative intervention.

Civilian Applications

In addition to the battlefield, tactical ultrasound can be useful in certain civilian settings. These settings are similar to battlefield settings where resources are severely limited and other patients may be competing for care. However, unique to this setting is pre-hospital use where long transport times to a hospital and a patient’s critical condition necessitates tactical decision-making including the need to call in additional resources such as aeromedical evacuation.

PREHOSPITAL USES

Use of ultrasound by emergency medical services (EMS) personnel is increasing throughout the world. Currently, pre-hospital ultrasound is being actively used in both air and ground EMS systems in Germany, France, Italy, England, Norway, and the United States1. Much of the experience with pre-hospital ultrasound has been in European EMS systems where transport to fixed facilities is often delayed in order to provide advanced medical care at point of injury. However, there is still a potential role in the United States, particularly for critically ill patients requiring aeromedical evacuation, or for patients in rural areas with extended transport times.45-48

The use of pre-hospital ultrasound can serve as an effective EMS triage tool to rapidly identify life threatening pathology requiring immediate intervention at the scene, influence the decision to transport to higher levels of care, and enhance communication between EMS personnel and hospital providers in order to expedite the mobilization of resources. Potential applications in the pre-hospital setting include the EFAST examination, limited echocardiography, abdominal aorta exam, lung sonography for patients with suspected pneumothorax or congestive heart failure, and rapid detection of right mainstem intubations.44 In patients with undifferentiated hypotension or cardiac arrest, pre-hospital ultrasound may assist in narrowing the differential of various shock states and provide early detection of pericardial tamponade, hemoperitoneum, abdominal aortic aneurysm, or tension pneumothorax.48-49 Cardiac standstill may also be diagnosed and assist in the decision to halt resuscitative efforts in the field.50

Pre-hospital ultrasound should be performed by qualified EMS personnel who have received appropriate training as recognized by professional specialty societies.17 Efforts are being made to validate appropriate training curriculums for these allied professionals.52 Although training EMS personnel to accurately perform pre-hospital ultrasound is certainly feasible, further research is needed with a focus on patient outcomes before its routine implementation into American EMS protocols.

MASS CASUALTY EVENTS

Mass casualty incidents (MCI) can be very similar to battlefield conditions, where resources become limited due to the overwhelming need of injured or medically ill patients. When confronted with a disaster scenario, healthcare personnel must prioritize the use of resources and make rapid treatment decisions, often with limited information, in order to provide the greatest good for the greatest number of patients. Several protocols have been described for the triage of victims in the setting of an MCI, including the proposal of a national guideline (SALT triage).54 The goal of these triage protocols is to quickly determine which victims require immediate, life saving interventions and which ones can wait longer for definitive management. In these situations, tactical ultrasound can enhance existing triage systems by identifying patients with imminent life threats as well as prioritizing the use of ancillary diagnostic and treatment modalities for patients with initially stable injuries.

Because it is portable, non-invasive, and can be performed rapidly in austere environments, point of care ultrasound has been utilized in several real-life disaster scenarios. In 1988, after an earthquake in Armenia left approximately 150,000 wounded, the FAST examination was performed during the initial triage of 400 trauma patients.55 Ninety-six of these patients were diagnosed with clinically significant injuries on ultrasound, and the authors reported only a 1% false negative rate with zero false positives. During the second Lebanon war, the FAST scan was again utilized to guide disposition of 102 casualties with traumatic abdominal injury to laparotomy, CT, or an observation protocol.56 In the aftermath of a mudslide in Guatemala, a variety of scans performed on 99 patients with a simple handheld device confirmed the presence of an emergent disorder in 12%, while ruling out disease in 42%.57

Table 4 illustrates how tactical ultrasound could be used throughout the triage process. Tactical ultrasound would most appropriately be used as an adjunctive tool in these situations in the overall assessment of injured patients. It should not be used as a separate triaging system or area as it would likely create a bottleneck effect of filtering a large number of critical patients through a dedicated ultrasound triage station leading to unnecessary delays in patient care.

|Triage Site |Types of Patients |Triage Category |Ultrasound Applications |Utility of ultrasound |

|Staging Area |Critically Injured |Red (immediate) |EFAST, ONSD |High |

|Staging Area |Severely Injured |Yellow (delayed) |EFAST, ONSD |High |

|Staging Area |Non-severely Injured |Green (minor) |EFAST |Moderate |

|Receiving Hospital |All patients |All categories |EFAST, ONSD, Soft tissue |Moderate |

| | | |(fracture and foreign | |

| | | |body) | |

Table 4. Uses of Ultrasound in Civilian Mass Casualty Incident

Conclusion:

Tactical ultrasound is the use of emergency ultrasound at the bedside to guide decision making in an environment where resources are severely limited and patient treatment and disposition decisions entail considering an evaluation of risk and resource allocation for all patients needing care. Decisions affecting the advanced triage and treatment of patients require the consideration of many variables including the patient’s appearance, physical exam and other diagnostic tests (if available). However, tactical ultrasound has the unique advantage of being an imaging modality that provides immediate focused answers at the bedside to the physician both performing the exam, caring for the patient and making treatment and disposition decisions that entail utilizing severely limited resources. Tactical ultrasound examinations are quick and focused and can be repeated as the patients condition changes. Because ultrasound machines are light, portable and battery powered, they are suited to austere environments where space and equipment are limited.

Tactical ultrasound is useful in a variety of settings and situations that range from the penetrating chest injuries on the battlefield to abdominal pain in the international space station. In both military and civilian mass casualty events, tactical ultrasound can serve as an advanced triage tool for disposition to the operating room for control of surgical bleeding, evacuation of intracranial hemorrhage or fixation of orthopedic injuries. In the future additional testing modalities may arise that supplant tactical ultrasound, but until then, it will be a mainstay of diagnosis, treatment and dispositions in these unique and austere environments.

BIBLIOGRAPHY:

1. 2010 World Almanac and Book of Facts, World Almanac Books, 2009, Pg. 176.

2. Sankoff J, Keyes LE., Emergency medicine resident education: making a case for training residents to perform and interpret bedside sonographic examinations. Ann Emerg Med. 1999 Jul;34(1):105-8

3. Akhtar S, Theodoro D, Gaspari R, et al., Resident training in emergency ultrasound: consensus recommendations from the 2008 Council of Emergency Medicine Residency Directors Conference. Acad Emerg Med. 2009 Dec;16 Suppl 2:S32-6.

4. Moore CL, Gregg S, Lambert M., Performance, training, quality assurance, and reimbursement of emergency physician-performed ultrasonography at academic medical centers. J Ultrasound Med. 2004 Apr;23(4):459-66.

5. Major R, Girling S, Boyle A., Ultrasound measurement of optic nerve sheath diameter in patients with a clinical suspicion of raised intracranial pressure. Emerg Med J. 2010 Aug 15.

6. Barillari A, Fioretti M., Lung ultrasound: a new tool for the emergency physician.

Intern Emerg Med. 2010 Aug;5(4):335-40.

7. Shiver SA, Lyon M, Blaivas M, Adhikari S., Prospective comparison of emergency physician-performed venous ultrasound and CT venography for deep venous thrombosis.

Am J Emerg Med. 2010 Mar;28(3):354-8.

8. Reardon R, Heegaard B, Plummer D, Clinton J, Cook T, Tayal V., Ultrasound is a necessary skill for emergency physicians. Acad Emerg Med. 2006 Mar;13(3):334-6.

9. Jones AE, Craddock PA, Tayal VS, Kline JA., Diagnostic accuracy of left ventricular function for identifying sepsis among emergency department patients with nontraumatic symptomatic undifferentiated hypotension. Shock. 2005 Dec;24(6):513-7.

10. Tayal VS, Cohen H, Norton HJ., Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy.

Acad Emerg Med. 2004 Sep;11(9):912-7.

11. Tayal VS, Beatty MA, Marx JA, Tomaszewski CA, Thomason., MHFAST (focused assessment with sonography in trauma) accurate for cardiac and intraperitoneal injury in penetrating anterior chest trauma. J Ultrasound Med. 2004 Apr;23(4):467-72.

12. Tayal VS, Graf CD, Gibbs MA., Prospective study of accuracy and outcome of emergency ultrasound for abdominal aortic aneurysm over two years. Acad Emerg Med. 2003 Aug;10(8):867-71.

13. American College of Emergency Physicians. Emergency ultrasound imaging criteria compendium. Ann Emerg Med. 2006 Oct;48(4):487-510.

14.

15.

16. American College of Emergency Physicians., American College of Emergency Physicians. ACEP emergency ultrasound guidelines-2001. Ann Emerg Med. 2001 Oct;38(4):470-81.

17. American College of Emergency Physicians, Emergency ultrasound guidelines. Ann Emerg Med. 2009 Apr;53(4):550-70.

18. Nelson BP, Melnick ER, Li J., Portable ultrasound for remote environments, part i: Feasibility of field deployment. J Emerg Med. 2010 Jan 23.

19. McNeil CR, McManus J, Mehta S., The accuracy of portable ultrasonography to diagnose fractures in an austere environment. Prehosp Emerg Care. 2009 Jan-Mar;13(1):50-2.

20. Do JR, McManus J, Harrison B., Use of ultrasonography to avoid an unnecessary procedure in the prehospital combat environment: a case report. Prehosp Emerg Care. 2006 Oct-Dec;10(4):502-6.

21. Brooks AJ, Price V, Simms M., FAST on operational military deployment. Emerg Med J. 2005 Apr;22(4):263-5.

22. Emergency War Surgery, Borden Institute, Washington DC, 2007

23. Book or article about Napoleon triage

24. War Surgery in Afghanistan and Iraq. Nessen, SC, Lounsbury, DE, Hetz SP. Borden Institute, Washington DC. 2008.

25. Ma OJ, Mateer JR, Ogata M, Kefer MP et al., Prospective analysis of a rapid trauma ultrasound as the primary adjunct modality for injured patient assessment. J Trauma 1995 39:492-500.

26. Ma OJ, Kefer MP, Mateer JR, Thomas B., Evaluation of hemoperitoneum using a single- vs multiple-view ultrasonographic examination. Acad Emerg Med. 1995 Jul;2(7):581-6.

27. Shih HC, Wen YS, Ko TJ, Wu JK, Su CH, Lee CH., Noninvasive evaluation of blunt abdominal trauma: prospective study using diagnostic algorithms to minimize nontherapeutic laparotomy., World J Surg. 1999 Mar;23(3):265-69

28. Sartori S, Tombesi P, Trevisani L et al. Accuracy of Thoracic Sonography in Detection of Pneumothorax After Sonographically Guided Comparison with Chest Radioigraphy. American Journal of Roentgenol 2007;188:37-41.

29. Blaivas M, Lyon M, Duggal S. A Prospective Comparison of Supine Chest Radiography and Bedside Ultrasound for the Diagnosis of Traumatic Pneumothorax. Academic Emergency Medicine 2005; 12(9): 844-850.

30. Nienaber A, Harvey M, Cave G., Accuracy of bedside ultrasound for the detection of soft tissue foreign bodies by emergency doctors. Emerg Med Australas. 2010 Feb;22(1):30-4.

31. Crystal CS, Masneri DA, Hellums JS, Kaylor DW, Young SE, Miller MA, Levsky ME., Bedside ultrasound for the detection of soft tissue foreign bodies: a cadaveric study. J Emerg Med. 2009 May;36(4):377-80

32. McArthur T, Abell B, Levsky M. A Procedure for Soft Tissue Foreign Body Removal Under Real-Time Ultrasound Guidance. Military Medicne Aug 2007; 172(8):858-9.

33. McNicholas MM, Brophy DP, Power WJ, Griffin JF: Ocular trauma: evaluation with US. Radiology 423-427, 1995.

34. Blaivas M. Bedside emergency department ultrasonography in the evaluation of ocular pathology. Academic Emergency Med 2000;7947-950.

35. Tayal VS, Neulander M, Norton HJ, Foster T, Saunders T, Blaivas M., Emergency department sonographic measurement of optic nerve sheath diameter to detect findings of increased intracranial pressure in adult head injury patients. Ann Emerg Med. 2007 Apr;49(4):508-14.

36. Rose JS, Bair AE, Mandavia D, Kisner DJ: The UHP ultrasound protocol: A novel ultrasound approach to the empiric evaluation of the undifferentiated hypotensive patient. Am J Emerg Med 19:299-302, 2001.

37. Nagdev AD, Merchant RC, Tirado-Gonzalez A, Sisson CA, Murphy MC., Emergency department bedside ultrasonographic measurement of the caval index for noninvasive determination of low central venous pressure. Ann Emerg Med. 2010 Mar;55(3):290-5

38. Shiver SA, Lyon M, Blaivas M, Adhikari S., Prospective comparison of emergency physician-performed venous ultrasound and CT venography for deep venous thrombosis. Am J Emerg Med. 2010 Mar;28(3):354-8.

39. Burnside PR, Brown MD, Kline JA., Systematic review of emergency physician-performed ultrasonography for lower-extremity deep vein thrombosis. Acad Emerg Med. 2008 Jun;15(6):493-8.

40. Tayal VS, Hasan N, Norton HJ, Tomaszewski CA: The effect of soft-tissue ultrasound on the management of cellulites in the emergency department. Acad Emerg Med 2006 Apr;13(4):384-8.

41. Miller AH, Roth BA, Mills TJ, Woody JR, Longmoor CE, Foster B. Ultrasound guidance versus the landmark technique for the placement of central venous catheters in the emergency department. Acad Emerg Med. 2002 Aug; 9(8):800-5.

43. Lyon M, Blaivas M. Intraoral ultrasound in the diagnosis and treatment of suspected peritonsillar abscess in the emergency department. Acad Emerg Med. 2005 Jan;12(1):85-8.

44. MA J, Mateer J, Blaivas M, eds. Emergency Ultrasound. New York: McGraw Hill; 2008. Chapter 4 Prehospital Ultrasound: Perspectives from Four Countries.

45. Heegaard W, Plummer D, Dries D, et al. Ultrasound for the air medical clinician. Air Med J. Mar-Apr 2004;23(2):20-23.

46. Melanson SW, McCarthy J, Stromski CJ, Kostenbader J, Heller M. Aeromedical trauma sonography by flight crews with a miniature ultrasound unit. Prehosp Emerg Care. Oct-Dec 2001;5(4):399-402.

47. Price DD, Wilson SR, Murphy TG. Trauma ultrasound feasibility during helicopter transport. Air Med J. Oct-Dec 2000;19(4):144-146.

48. Heegaard W, Hildebrandt D, Reardon R, Plummer D, Clinton J, Ho J. Prehospital Ultrasound Diagnosis of Traumatic Pericardial Effusion. Acad Emerg Med. Mar 14 2009.

49. Atkinson PR, McAuley DJ, Kendal RJ, et al. Abdominal and cardiac evaluation with sonography in shock (ACES): an approach by emergency physicians for the use of ultrasound in patients with undifferentiated hypotension. Emerg Med J 2009;26(2):87-91.

50. Blaivas M, Fox JC. Outcome in cardiac arrest patients found to have cardiac standstill on the bedside emergency department echocardiogram. Acad Emerg Med 2001;8(6):654-7.

51. Walcher F, Weinlich M, Conrad G, et al. Prehospital ultrasound imaging improves management of abdominal trauma. Br J Surg. Feb 2006;93(2):238-242.

52. Heegaard W, Nelson B, Hildebrandt D, Ho J, Spear D. Paramedic Prehospital Ultrasound Training Evaluation. Academic Emergency Medicine. 2008 15(5):S46.

54. Lerner, EB et al. Mass Casualty Triage: An Evaluation of the Data and Development of a Proposed National Guideline. Disaster Medicine and Public Health Preparedness. 2008;2(Suppl 1):S25-S34.

55. Sarkisian AE, Khondkarian RA, Amirbekian NM et al. Sonographic screening of mass casualties for abdominal and renal injuries following the 1988 Armenian earthquake. J Trauma 1991;31:247–250.

56. Beck-Razi N, Fischer D, Michaelson M et al. The utility of focused assessment with sonography for trauma as a triage tool in multiple-casualty incidents during the second Lebanon war. J Ultrasound Med 2007;26:1149–1156.

57. Dean AJ, Ku BS, Zeserson EM. The utility of handheld ultrasound in an austere medical setting in Guatemala after a natural disaster. Am J Disaster Med 2007;2(5):249–256.

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