Download White Paper on Tactical Ultrasound

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
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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
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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
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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
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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
I
Team
Self aid/Buddy aid
Squad
Combat lifesaver
Platoon
Combat Medic
Company/Battalion Battalion Aid Station
II
Division
Care
Basic first aid
Initial emergency treatment
Initial stabilization and resuscitation
Medical Company
FST
MFST
Expeditionary Medical
Unit
Medical management and
stabilization
Life saving resuscitation and surgery
III/IV
Corps/Theater
CSH, Theater Hosptial,
USS MERCY, USS
COMFORT
Comprehensive
Resuscitation and Surgery
V
Continental US
MEDCEN
Definitive Care and Rehabilitation
Level I
5
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 lifethreatening 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
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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, noncombat 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
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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 intraabdominal 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 intraabdominal 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
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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
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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.
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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
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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
Central and Peripheral IV Access
Guidance
Nerve Blocks
Abscess Drainage
Foreign Body Removal
Arthrocentesis
Thoracentesis
Lumbar Puncture
Table 2. Types of Emergency Bedside Ultrasound Examinations Performed on the
Battlefield
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Exam
Level
1
High
High
High
Degree of Utility
Level 2
Level 3
EFAST
High
High
Resuscitation
High
High
Musculoskeletal (Long Bone
Moderate
Low
Fracture)
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
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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
14
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
15
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
Staging Area
Critically Injured
Staging Area
Severely Injured
Staging Area
Non-severely
Injured
All patients
Receiving
Hospital
Triage
Category
Red
(immediate)
Yellow
(delayed)
Green (minor)
Ultrasound
Applications
EFAST, ONSD
Utility of ultrasound
EFAST, ONSD
High
EFAST
Moderate
High
All categories
EFAST, ONSD, Moderate
Soft tissue
(fracture and
foreign body)
Table 4. Uses of Ultrasound in Civilian Mass Casualty Incident
16
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.
17
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