Chapter 35
Chest Trauma
EMS 475
DR SADIA FARHAN
Learning objectives
At the end of this lecture students must be able to:
• Interpret the basics of clinical anatomy of thorax
• Describe the basics of pathophysiology related to
thoracic injuries
• Interpret the immediate general management of
patient with thoracic injuries
• Recognize and differentiate between the fractures of
thoracic cage
• Outline the emergency field management of common
injuries of lungs, heart and medistional structures
• Prioritize and justify the referral of patient to trauma
centre according to the assessment of thoracic trauma
Introduction
• Annually, thoracic
trauma causes:
• One in four trauma
deaths are due to
thoracic injuries.
© PhotoStock-Israel /Alamy Images
– 700,000 +
emergency
department visits
– 18,000+ deaths
Anatomy
• Thorax—bony cage over chest organs
Anatomy
• Diaphragm inserts below 4th or 5th rib
– Size/dimension of thoracic cavity varies during
respiration
Anatomy
• Sternum
– Consists of:
• Superior manubrium
• Central sternal body
• Inferior xyphoid process
• Clavicle
– Connects to the manubrium and overlies the first rib
• Scapula
– Overlies posterior aspect of the upper thoracic cage
Anatomy
• 12 pairs of ribs attach to
12 thoracic vertebrae.
– First 7 pairs attach
directly to sternum
– 8–10 attach indirectly to
sternum
– 11 and 12 are “floating
ribs”
Anatomy
• Intercostal space houses:
– Intercostal muscles
– Neurovascular bundle
•
Mediastinum contains:
–
–
–
–
–
–
Heart and great vessels
Esophagus
Lymphatic channels
Trachea
Mainstem bronchi
Vagus and phrenic nerves
Anatomy
• Heart resides inside pericardium
– Anterior portion is the right ventricle
– Mostly protected anteriorly by the sternum
– Average cardiac output: volume of blood pumped
by heart in one minute
stroke volume ×pulse rate/ min
70 × 70 = 4,900 mL/min
Anatomy
• Aorta: largest artery in body
– Three points of attachment:
• Annulus
• Ligamentum arteriosum
• Aortic hiatus
• Lungs occupy most space in thoracic cavity
– Lined with pleura
– Pleura is separated by viscous fluid
• Keeps lungs from collapsing on exhalation
Anatomy
• Diaphragm: primary breathing muscle
– Breathing effort can be helped by accessory
muscles.
Physiology
• Primary functions of thorax:
– Maintain oxygenation and ventilation.
– Maintain circulation.
• Breathing process includes:
– Delivery of oxygen to body
– Elimination of carbon dioxide
Physiology
• Brain stimulates breathing via chemoreceptors.
– If CO2 is too high, respiratory rate increases.
– Hypoxic drive: secondary mechanism
• Intercostal and accessory muscles pull chest wall
away from the body as the diaphragm contracts
downward.
– Negative pressure draws air through mouth and nose
to alveolar spaces.
• Replaces air in the alveoli
Physiology
• Blood is delivered by pulmonary circulation to
capillaries adjacent to alveoli.
– Has low O2 and high CO2 concentrations
– Oxygenation process delivers O2 to blood
• Ventilation: how CO2 leaves the body
– CO2 diffuses down its concentration gradient and
enters air within the alveoli.
– Positive pressure is created within the thorax and
air is exhaled.
Pathophysiology
• Traumatic injury to chest may compromise:
– Ventilation
– Oxygenation
– Circulation
• Two mechanisms of injury:
– Blunt
– Penetrating
• Two basic injury patterns
– Closed
– Open
Pathophysiology
• Blunt trauma may lead to:
– Fracture of ribs, sternum, areas of chest wall
– Bruise of lungs and heart
– Damage to aorta
– Broken ribs lacerating intrathoracic organs
– Organs torn from attachment
Pathophysiology
• Thoracic trauma may impair cardiac output.
– Blood loss
– Pressure change
– Vital organ damage
– Combination of these
Pathophysiology
• Ventilatory impairments can be rapidly fatal.
– Shallow breathing reduces minute volume.
– Air entering pleural space compresses lungs and
decreases tidal volume.
– Blood collection prevents full lung expansion.
Pathophysiology
• Other complications include:
– Atelectasis reduces area for gas exchange.
– Bruised lung tissue may cause hypoxemia.
– Tearing or rupture of respiratory structures
prevents O2 from reaching alveoli.
Scene Size-Up
• Be sure scene is safe to enter.
• Follow standard precautions.
• After identifying number of patients:
– Triage patients and request resources.
– Determine MOI if possible.
Primary Assessment
• Form a general impression.
– Assess level of consciousness.
– Observe the neck for:
• Accessory muscle use during breathing
• Extended or engorged external jugular veins
• Airway and breathing
– Assess while performing spinal immobilization.
– Signs of obstruction may include:
• Stridor
• Hoarseness
• Alterations in mental status
Primary Assessment
• Airway and breathing (cont’d)
– Abnormal findings may include:
• Tachypnea
• Hemoptysis
• Retractions
– Immediate manage airway impairment:
• Manually immobilize patient.
• Use jaw-thrust maneuver.
– Identify and manage impairment of oxygenation
and ventilation.
Primary Assessment
• Airway and breathing (cont’d)
– Address life-threats first.
– Apply occlusive dressing to penetrating injuries.
– Assess ventilation and oxygenation.
• Evaluate skin circulation.
• Decreasing O2 saturation may indicate hypoxia.
• Watch for impending tension pneumothorax signs.
Primary Assessment
• Circulation
– Check pulses.
• Tachycardia is not always associated with hypovolemia.
• Low heart rate does not rule out hypovolemia or shock.
• Thready or weak pulse may suggest volume loss.
Primary Assessment
• Circulation (cont’d)
– Irregular pulse suggests:
• Hypoxia
• Hypoperfusion
• Serious underlying injuries or shock
– Auscultate the heart.
• Note if heart sounds are easily heard or muffled.
– If shock suggested, may not be from thorax.
• Obtain history and complete physical.
Primary Assessment
• Transport decision
– Priorities: patients
with ABC problems
– If signs of poor
perfusion/
– inadequate
breathing:
• Transport quickly.
• Perform assessment
en route.
History Taking
• May need to be done en route
• Obtain relevant patient history (SAMPLE).
• Questions about event should focus on MOI.
Secondary Assessment
• Includes a head-to-toe assessment
– Check for injuries that may compromise ABCs.
• Obtain full set of vitals.
• Monitoring equipment can aid assessment
• If chest injury is isolated with limited MOI,
focus on:
– Isolated injury
– Patient’s complaint
– Body region affected
Secondary Assessment
• If significant trauma affects multiple systems:
– Perform full body scan using DCAP-BTLS.
– Inspect region for deformities.
– Palpate for tenderness.
– Check for lacerations and swelling.
Reassessment
• Obtain repeated assessments of:
– Vital signs
– Oxygenation
– Circulation
– Breath sounds
• If pneumothorax is suspected, patient should
be considered unstable.
– Reassess at least every 5 minutes.
Flail Chest
• May result from
blunt force
mechanisms
• Two or more
adjacent ribs
fractured in two or
more places
– Segment becomes
separated from
chest wall
Flail Chest
• Location and size affects degree that chest
wall and air movement are impaired.
– Flail sternum (most extreme)
• Underlying pressure causes paradoxical
movement of segment and rest of chest wall.
• May not be initially apparent
– Palpate for rib cage fractures and crepitus.
Flail Chest
• Pneumothorax or hemothorax may occur if
bone fragments are driven into the body.
– Pain may prevent adequate tidal volume.
• Limits the ability to compensate for flail segment
• Management may involve:
– Positive-pressure ventilation
– Positive end-expiratory pressure
Flail Chest
• Assessment and management
– Signs and symptoms include:
• Hypoxia
• Hypercarbia
• Pain
– Palpation may reveal:
• Crepitus
• Tenderness
• Dissection of air into tissue
– Auscultation may reveal:
• Decreased or absent breath sounds
Flail Chest
• Assessment and management (cont’d)
– Poses a threat to patient’s ability to breathe
• Intubation and positive-pressure ventilation may be
needed.
– Stabilization of flail segment is controversial.
Rib Fractures
• Most common thoracic injury
– Pain contributes to:
• Inadequate ventilation
• Atelectasis
• Pneumonia from inadequate respiration
• Blunt trauma may result in fracture at:
• Point of impact
• Edge of object
• Posterior angle of rib
Rib Fractures
• Associated injuries can be:
– Ribs 4–9
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•
•
•
Aortic injury
Tracheobronchial injury
Pneumothorax
Vascular injury
– Ribs 9–11
• Intra-abdominal injury
Rib Fractures
– Patients report:
• Pleuritic chest pain
• Mild dyspnea
– Exam shows:
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•
•
•
Chest wall tenderness
Soft-tissue injury
Crepitus
Subcutaneous emphysema
Rib Fractures
• Assessment and management (cont’d)
– Management focuses on:
• ABCs and evaluating for other injuries
– Administer supplemental O2
– Gently splint chest wall.
– Consider intravenous analgesic.
Sternal Fractures
• One in 20 patients with blunt thoracic
trauma can have sternal fracture
– Associated with other injuries, including:
• Myocardial contusions
• Intra-abdominal injuries
• Assessment and management
– Patient reports pain over anterior part of chest.
– Palpation may reveal:
• Tenderness
• Crepitus
• Possible flail segment
Sternal Fractures
• Assessment and management (cont’d)
– Perform an ECG rhythm analysis.
– Supportive treatment only
• ABCs
• Manage associated injuries.
• Analgesics
Clavicle Fractures
• One of the most common fractures
• Assessment and management
– Patient will:
• Report pain in the shoulder
• Usually hold arm across front of body
– Splint fracture with a sling and swathe.
• Apply gentle upward support to the olecranon process
of the ulna.
• Knot should be tied on the side of the neck
Br ak
Simple Pneumothorax
• Accumulation of air/gas in
pleural cavity
– Air enters through a hole in
the chest wall or lung causes
lung collapse on affected side
• Delayed or improper
treatment may lead to a
tension pneumothorax
Simple Pneumothorax
• Assessment and management (cont’d)
– Cover large open wounds immediately.
• Nonporous dressing secured on three sides
– Maintain ABCs, provide high-concentration O2.
• If tension develops, dressing may need to be removed
to release trapped air.
Open Pneumothorax
• Occurs when chest wall defect allows air into
thoracic space
– Results from penetrating chest trauma
– Negative pressure draws air into pleural space.
– As size increases, lung loses ability to expand.
Open Pneumothorax
• If hole is larger than
glottis opening, air
is likely to enter
chest wall.
– Creates a “sucking
chest wound”
Open Pneumothorax
• Assessment and management
– Signs and symptoms may include:
• Tachycardia and tachypnea
• Restlessness
– Physical assessment shows:
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•
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Chest wall defect
Impaled object
Sucking chest wound
Bubbling wound
Subcutaneous emphysema
Open Pneumothorax
• Assessment and
management
(cont’d)
– Treat immediately.
• Convert wound to a
closed injury.
• Place on high-flow
supplemental O2 via
nonrebreathing
mask.
Tension Pneumothorax
• Life-threatening
condition from air
accumulation
within interpleural
space
– Results from open
or closed injury
Tension Pneumothorax
• As air accumulates, pressure builds against
surrounding tissue.
– Compresses the lung, which diminishes:
• Ability to oxygenate blood
• Ability to eliminate CO2
• Pressure causes eventual lung collapse and
mediastinum to shift.
– May exceed pressure in major venous
structures
– If venous return decreases, the body will
increase heart rate.
Tension Pneumothorax
• Assessment and management
– Classic signs may include:
• Absence of breath sounds on affected side
• Pulsus paradoxus
• Tracheal deviation
– Tachycardia is induced because blood cannot
return to heart.
• Accumulates in great vessels
• Pressure pushes blood into jugular vein.
Tension Pneumothorax
• Assessment and management (cont’d)
– During normal inspiration:
• Negative pressure decreases blood return.
• Preload and systolic blood pressure decrease.
– Jugular veins are distended when engorged 1 to 2 cm
above the clavicle.
– May show:
– trachea deviation from affected side
– diminished breath sounds
– pleuritic chest pain and dyspnea
Tension Pneumothorax
• Assessment and management (cont’d)
– Administer immediate high-flow supplemental O₂.
– Inspect the chest.
– Cover open wounds with dressing.
– If elevated pressure is suggested:
• May need to perform a needle decompression
Hemothorax
• Occurs when blood
accumulates within
pleura
– Commonly caused
by lung parenchyma
tearing
– Collection of blood
compresses and
displaces lung
Hemothorax
• Hemopneumothorax
– Blood and air in the
pleural space
• Massive hemothorax
– Accumulation of more
than 1,500 mL of
blood within pleura
Hemothorax
• Assessment and management
– Signs include:
• Ventilatory insufficiency
• Hypovolemic shock
– Findings that differentiate from other injuries:
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Lack of tracheal deviation
Dullness on percussion
Flat neck veins with hypovolemia
Distended neck veins with increased pressure
Hemothorax
• Assessment and management (cont’d)
– Prehospital management:
•
•
•
•
Supportive care
Rapid transport
High-flow supplemental O2
Two large-bore peripheral IV
Pulmonary Contusion
• Alveolar and capillary damage results from
lung tissue compression against chest wall.
– Injury may lead to:
• Loss of fluid and blood into involved tissues
• White blood cell migration into area
• Local tissue edema
• Local surfactant in alveoli is diluted.
– Causes atelectasis
• Delivery of O2 is reduced, causing hypoxia
Pulmonary Contusion
• Assessment and management
– Hypoxia and CO2 retention may cause:
• Respiratory distress
• Tachycardia
• Agitation
– Auscultation may reveal:
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•
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Wheezes
Rhonchi
Rales
Diminished lung sounds
Pulmonary Contusion
• Assessment and management (cont’d)
– Treatment includes:
• Managing airway
• Using caution when administering IV fluids
• Administering small amounts of analgesics for pain
Cardiac Tamponade
• Excessive fluid in pericardial sac, causing
– Compression of the heart
– Decreased cardiac output
Cardiac Tamponade
• Hemodynamic effects determined by:
– Size of pericardium perforation
– Rate of hemorrhage
– Chamber of heart involved
• Mortality varies.
• Can occur in both medical and trauma
conditons
– Medical—slow fluid collection
– Trauma—bleeding is rapid.
Cardiac Tamponade
• Continued bleeding increases pressure in the
pericardium.
– Atria and vena cavae compress.
– Preload delivery is drastically reduced.
– Heart increases rate to compensate.
Cardiac Tamponade
• Assessment and management
– 30% diagnosed will have Beck triad:
• Muffled heart tones
• Hypotension
• JVD
– Classic finding: electrical alternans in ECG strip
– Findings typical of shock, including:
• Weak or absent peripheral pulses
• Cyanosis
• Tachycardia or tachypnea
Electrical alternans
Cardiac Tamponade
• Assessment and management (cont’d)
– Treatment includes:
•
•
•
•
Assess and manage ABCs.
Ensure adequate O2 and establishing IV access.
Provide a rapid fluid bolus.
Rapidly transfer to trauma center.
Cardiac Tamponade versus Tension
Pneumothorax
Myocardial Contusion
• Sudden deceleration of chest wall may cause
collision of heart to sternum.
– Characterized by:
• Local tissue contusion and hemorrhage
• Edema
• Cellular damage within myocardium
Myocardial Contusion
• Damage to myocardial tissues may cause:
– Ectopic activity
– Dysrhythmias
• Structural changes may include:
– Ventricular septal defect
– Myocardial rupture or aneurysm
– Coronary artery occlusion
Myocardial Contusion
• Assessment and management
– Signs and symptoms include:
• Sharp, retrosternal chest pain
• Soft-tissue or bony injury in area
• Crackles or rales on auscultation
– Treatment includes:
• Nonspecific supportive care
• Fluid resuscitation
• Consulting with medical control before administering
antidysrhythmic agents
Commotio Cordis
• Cardiac arrest caused by a direct blow to the
thorax during the repolarization period
– Result of chest wall impact directly over heart
– Second most common cause of sudden cardiac
death in young male athletes
Commotio Cordis
• Assessment and management
– Signs and symptoms may include:
• Unresponsiveness
• Cyanotic
• Tonic-clonic seizures
– Survival rates increased because of:
• Increased awareness
• CPR preparation
• Accessibility of AED at sporting events
Traumatic Aortic Disruption
• Dissection or rupture of the aorta
• Usually caused by crashes and falls
– Aorta is injured at fixed points by shearing forces.
– Impact causes the aortic arch to swing forward.
– Tension and area rotation cause aorta to rupture
at point of attachment.
Traumatic Aortic Disruption
• If intima is
torn, blood can
dissect along
the media.
• Severe injuries
may allow
blood to leak
from all layers.
Traumatic Aortic Disruption
• Assessment and management
– Symptoms vary and may include:
•
•
•
•
Tearing pain behind sternum or in the scapula
Hypovolemic shock
Dyspnea
Altered mental state
– Recognition often from suspicion based on MOI
• Assessment of extremity pulses is important
Traumatic Aortic Disruption
• Assessment and management (cont’d)
– Assess and manage ABCs.
– Gradual IV hydration to treat hypotension
– Do not use pressor agents.
– Expedite transport to trauma center.
Great Vessel Injury
• Great vessels protected by bony structures and
other tissues (except for aorta)
– Injuries more likely with penetrating trauma
– Injuries may result in occlusion or artery spasm
• .Presentation may include:
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–
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–
–
Pain
Pallor
Paresthesias
Pulselessness
Paralysis
Great Vessel Injury
• Assessment and management
– If bleeding not prevented, presentation includes:
• Hypovolemic shock
• Hemothorax
• Cardiac tamponade
– Procedures for acute blood loss
• Establish IV for hydration during transport.
• Treat pericardial tamponade immediately.
• Do not use pneumatic antishock garment.
Diaphragmatic Injuries
• Occurs in a small percentage of trauma
• Most occur on left side
– Liver protects right side.
• Recovery is inhibited by pressure differences
between abdominal and thoracic cavities.
Diaphragmatic Injuries
• Three phases:
– Acute—begins at injury; ends with recovery
from other injuries
– Latent—entrapment of abdominal contents
– Obstructive—abdominal contents herniate
through defect
• Tension gastrothorax
– Herniation of abdominal contents into thoracic
cavity, causing pressure to:
• Compress lung on affected side.
• Compromise circulatory function.
Diaphragmatic Injuries
© SIU Bio Med Comm./Custom Medical Stock Photo
Diaphragmatic Injuries
• Assessment and management (cont’d)
– Acute phase:
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•
•
•
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Hypotension
Tachypnea
Bowel sounds in chest
Chest pain
Absent breath sounds
– Obstructive phase:
•
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Nausea and vomiting
Abdominal pain
Constipation
Dyspnea
Abdominal distension
Diaphragmatic Injuries
• Assessment and management (cont’d)
– Management focus: maintaining oxygen and
providing rapid transport
• Elevate head of backboard.
• Positive-pressure ventilation
• NG tube placement (if allowed by protocol)
– Definative surgical repair
Esophageal Injuries
• Rapidly fatal injury in GI system
• Assessment and management
– Signs and symptoms include:
• Pleuritic chest pain
• Subcutaneous emphysema
• Associated tracheal injury
– No specific therapy in the prehospital setting
– Do not give anything orally.
Tracheobronchial Injuries
• Rare, typically caused by penetrating injuries
– High mortality rate
– Allows for rapid movement of air into pleural
space, causing a pneumothorax
• May progress to tension pneumothorax
Tracheobronchial Injuries
• Assessment and management
– Presentation varies and may include:
• Hoarseness
• Dyspnea and tachycardia
• Respiratory distress
– Focuses on ABCs
• Bag-bask ventilation instead of intubation
• Avoid high ventilatory pressure.
Traumatic Asphyxia
• Induced by traumatic injury that forcefully
compresses the thoracic cavity
– Causes pressure to major veins of the head, neck,
and kidneys
• Causes rupture of the capillary beds
Traumatic Asphyxia
• Assessment and
management
– Physical findings:
• Cyanosis of head,
upper extremities,
and torso
• Ocular hemorrhage
• Swollen and
cyanotic facial
structures
© Chuck Stewart, MD.
Traumatic Asphyxia
• Assessment and management (cont’d)
– Provide high-flow supplemental O2.
– Take cervical spine precautions.
– Obtain IV access with two large-bore IV lines.
– Transport to nearest trauma center.
Traumatic Asphyxia
• Assessment and management (cont’d)
– Provide high-flow supplemental O2.
– Take cervical spine precautions.
– Obtain IV access with two large-bore IV lines.
– Transport to nearest trauma center.
Summary
• Thorax contains ribs, thoracic vertebrae,
clavicle, scapula, sternum, heart, lungs,
diaphragm, great vessels, esophagus,
lymphatic channels, trachea, mainstem
bronchi, and nerves.
• Oxygenation, ventilation, and some aspects of
circulation take place in the thorax.
• Thoracic injuries can cause air or blood in the
lungs or prevent organs from moving properly.
Summary
• A thoracic trauma assessment begins with
scene size-up and ABCs assessment.
• When assessing breathing, note any injury to
the thorax, which may indicate underlying
injuries.
• Consider ventilation and oxygenation
adequacy.
• Always consider spine stabilization.
Summary
• Managing chest injuries includes maintaining
airway, ensuring oxygenation and ventilation,
supporting circulation, and transporting quickly.
• Chest wall injuries include flail chest, rib
fractures, sterna fractures, and clavicle fractures.
• In flail chest, two or more ribs are broken in two
or more places, which can result in a free-floating
rib segment.
Summary
• Flail chest management includes airway
management and possible positive-pressure
ventilation.
• Rib fractures cause significant pain and may
prevent adequate ventilation.
• Rib fracture management should focus on the
ABCs and gentle splinting of the chest.
Summary
• Lung injuries include simple pneumothorax,
open pneumothorax, tension pneumothorax,
hemothorax, and pulmonary contusion.
• In a pneumothorax, air leaks into the pleural
space from an opening in the chest or the
surface of the lung.
• Management of a pneumothorax starts with
the ABCs and high-concentration oxygen
administration.
Summary
• A tension pneumothorax results from air
collection in the pleural space, and is a lifethreatening condition.
• Patients with a tension pneumothorax should
be placed on high-flow supplemental oxygen
via a nonrebreathing mask. Cover open
wounds with a nonporous or occlusive
dressing.
Summary
• A hemothorax is the accumulation of blood
between the parietal and visceral pleura.
• If a patient with a hemothorax does not
require airway intervention, place the patient
on high-flow supplemental oxygen via a
nonrebreathing mask.
• A hemopneumothorax is the collection of
both blood and air in the pleural space.
Summary
• A pulmonary contusion occurs from compression of the
lung, resulting in alveolar and capillary damage, edema,
and hypoxia.
• If a patient has a pulmonary contusion or cardiac
tamponade, assess and manage the ABCs and consider
administering IV fluids.
• Myocardial injuries include cardiac tamponade,
myocardial contusion, myocardial rupture, and commotio
cordis.
Summary
• Cardiac tamponade occurs when excessive
fluid builds up in the pericardial sac around
the heart, which compresses the heart and
compromises stroke volume.
• Treating cardiac tamponade begins by
managing the ABCs, ensuring adequate
oxygen delivery, and establishing IV access.
Pericardiocentesis is the ultimate treatment
option.
Summary
• Myocardial contusion is blunt trauma to the
heart, and may cause hemorrhage, edema,
and cellular damage.
• Management for myocardial contusion is
supportive, but should also include cardiac
monitoring and establishing IV access.
• Myocardial rupture is perforation of one or
more elements of the anatomy of the heart,
occurring from blunt or penetrating trauma.
Summary
• Management for myocardial rupture should
include supportive care and rapid transport to
a trauma center for a thoracotomy.
• Commotio cordis occurs from a direct blow to
the chest during a critical portion of the
heart’s repolarization period.
• ALS treatment for commotio cordis must
follow standard ACLS guidelines for sudden
cardiac arrest.
Summary
• Vascular injuries include traumatic aortic
disruption and great vessel injury.
• Traumatic aortic disruption is the ripping of
the aorta.
• Management for traumatic aortic disruption
focuses on symptom control.
• Other injuries include diaphragmatic injuries,
esophageal injuries, tracheobronchial injuries,
and traumatic asphyxia.
Credits
• Chapter opener: Courtesy of ED, Royal North Shore Hospital/NSW
Institute of Trauma & Injury
• Backgrounds: Blue–Jones & Bartlett Learning. Courtesy of MIEMSS;
Gold–Jones & Bartlett Learning. Courtesy of MIEMSS; Green–Courtesy
of Rhonda Beck; Red–© Margo Harrison/ShutterStock, Inc.
• Unless otherwise indicated, all photographs and illustrations are under
copyright of Jones & Bartlett Learning, courtesy of Maryland Institute
for Emergency Medical Services Systems, or have been provided by the
American Academy of Orthopaedic Surgeons.