Lesson 6
Circulation,
Hemorrhage, and Shock
Circulatory System
• A functioning circulatory
system requires:
– A heart that pumps
adequately
– Intact blood vessels to
contain the fluids (blood)
being pumped
– Adequate amount of
blood (fluid) to fill the
vascular container
Metabolism
• All cells require energy to function
• Energy is stored within the cell in the form
of adenosine triphosphate (ATP)
molecules
• Aerobic metabolism
– Oxygen is required for efficient production of
ATP (energy)
• Anaerobic metabolism
– Inadequate oxygen results in decreased
energy (ATP) production and accumulation of
lactic acid
Shock
• Results from inadequate energy
production to sustain life
• Any condition that causes generalized
cellular hypoperfusion
• Leads to inadequate cellular oxygenation
that does not meet metabolic needs
Hypoperfusion (1 of 2)
• Results from:
– Loss of blood (either externally or internally)
• Most common cause of shock in trauma
– Impaired pumping of blood
– Dilation of the blood vessels (increased
vascular space)
Hypoperfusion (2 of 2)
• The end result is a decrease in circulating
volume and red blood cells (RBCs) moving
through the capillary beds to deliver
oxygen to the cells
• Lack of oxygen impairs metabolism
• Impaired metabolism decreases energy
production
Shock in Trauma
• Classifications
– Hypovolemic
– Distributive
– Cardiogenic
Hypovolemic Shock (1 of 2)
• The most common cause of shock in the
trauma patient
– Due to hemorrhage
• Loss of RBCs impairs oxygen transportation
– In any trauma patient with shock, assume
hemorrhage is the cause until proven
otherwise
Hypovolemic Shock (2 of 2)
The values and descriptions for the criteria listed for these classes of shock
should not be interpreted as absolute determinants of the class of shock, as
significant overlap exists.
Distributive Shock
• Neurogenic “shock”
– Decreased systemic vascular resistance due
to vasodilation
• Most common cause is spinal cord injury
Cardiogenic Shock
• Intrinsic
– Blunt cardiac trauma leading to muscle
damage and/or dysrhythmia
– Valvular disruption
• Extrinsic
– Pericardial tamponade
– Tension pneumothorax
Assessment (1 of 7)
Evaluate:
– Hemorrhage
– Level of consciousness
– Skin
– Pulse
– Respiration
– Blood pressure
– Confounding factors
Assessment (2 of 7)
• Hemorrhage
– If present must be controlled ASAP
• External
– Address in the prehospital setting
• Internal
– Transport to appropriate destination
Assessment (3 of 7)
• Level of consciousness (LOC)
– Decreased cerebral perfusion results in
altered LOC
– Assume altered LOC is due to shock, and
treat accordingly
– Other causes of altered LOC will not kill as
rapidly as shock
Assessment (4 of 7)
• Skin
– Color
– Temperature
– Moisture
– Capillary refill
• Pulse
– Rate
– Quality
– Location
Assessment (5 of 7)
• Respiration
– Hypoxia, hypercarbia, and acidosis stimulate
the respiratory center
– Increasing ventilatory rate may be the earliest
sign of shock
– Intolerance of oxygen face mask suggests
hypoxia
Assessment (6 of 7)
• Blood pressure (BP)
– Not the determinant of shock
• 30% blood loss before BP drops
– Not part of the primary assessment
– Trends are crucial
– Adequate blood pressure does not equate to
adequate tissue perfusion
– Treatment is not aimed at returning BP to
normal
Assessment (7 of 7)
Complicating factors
– Patient age
– Medications
– Pregnancy
– Pre-existing conditions
Shock Without Obvious
Cause (1 of 4)
• Assume the patient is bleeding
somewhere, even if you can’t see it
– Internal hemorrhage
– Fracture
Shock Without Obvious
Cause (2 of 4)
• Internal hemorrhage
– The chest and abdomen can hold large
volumes of blood
– The chest is usually associated with visible
external signs of trauma; the abdomen often
is not
Shock Without Obvious
Cause (3 of 4)
• Internal hemorrhage
(cont’d)
– Abdominal trauma is
a cause of significant
hidden hemorrhage
– Assume abdominal
trauma if hypovolemic
shock is not
otherwise explainable
Courtesy of Peter T. Pons, MD, FACEP
Shock Without Obvious
Cause (4 of 4)
• Fractures
– Multiple fractures
– Blood loss into the surrounding soft tissues
from a long-bone fracture, such as the femur,
can be significant
– Blood loss into the pelvic and abdominal
spaces from a pelvis fracture can be massive
Mechanism of Injury and
Shock (1 of 3)
• Penetrating injuries
– Object traverses the
chest, abdomen, or
extremity
– May injure organs,
tissues, and blood
vessels along its
pathway
Courtesy of Lance Stuke, MD, MPH
Mechanism of Injury and
Shock (2 of 3)
• Blunt injuries
– Path of injury is less visible
– Force (energy) is applied to the trunk and
extremities
– Energy is transmitted to the thoracic and
abdominal organs and bones causing
damage
Mechanism of Injury and
Shock (3 of 3)
• Blunt injuries (cont’d)
– Compression, cavitation, and deceleration
can tear and shear organs and blood vessels
and fracture bones
– Damaged organs, tissues, and blood vessels
bleed into the surrounding cavities and tissue
– As the amount of blood lost increases, signs
of shock develop
Injuries Commonly Associated
With
Hemorrhagic Shock
Traumatic Aortic Rupture
(Tear)
• Usually occurs at the
junction of the mobile and
fixed portions of the aorta
just beyond the left
subclavian artery
• 80% to 85% die prehospital
from intrathoracic
hemorrhage
McSwain NE Jr, Paturas JL: The Basic EMT: Comprehensive
Prehospital Patient Care, ed 2, St. Louis, 2001, Mosby
– Of those who survive, 50% die
within 48 hours if not treated.
Hemothorax
• Bleeding into the
pleural cavity
• Blunt or penetrating
mechanism
• Each hemithorax can
hold up to 30% to
40% of a patient’s
total blood volume
Abdominal Organ Injury (1 of 2)
• Results from a blunt or penetrating
mechanism
• Injury to:
– Solid organs (liver, spleen, kidney, pancreas)
• Results in hemorrhage that varies from mild to lifethreatening
• May also be associated with leak of enzymes, bile,
or urine into abdomen
Abdominal Organ Injury (2 of 2)
• Injury to (cont’d):
– Hollow organs (small and large bowel)
• Usually not a cause of major blood loss
• Leak contents and cause peritonitis
Fractures (1 of 2)
• Major or multiple fractures can lead to
significant blood loss
• Femur or pelvic fractures are the most
common cause
• Do not underestimate blood loss due to
multiple fractures
Fractures (2 of 2)
Fracture
(Isolated)
Single rib
Radius or
ulna
Humerus
Tibia or
fibula
Femur
Pelvis
Blood Loss
(ml)
125
250–500
750
500–1000
1000–2000
Massive
Courtesy Norman McSwain, MD, FACS, NREMT-P
Rib Fractures
• Most common
thoracic injury
• Usually in ribs 4–8,
laterally
• May be associated
with injuries to
intercostal blood
vessels, liver,
spleen, or lung
Courtesy of Peter T. Pons, MD, FACEP.
Injuries Commonly Associated
With
Distributive Shock
Neurogenic “Shock”
• Secondary to spinal cord injury, usually
cervical spine (down to T6)
• Loss of sympathetic system vascular tone
– Blood vessels dilate
– Blood return to the heart decreases and
cardiac output drops
• Perfusion and tissue oxygenation are
usually maintained
– Skin remains warm and dry
Injuries Commonly Associated
With
Cardiogenic Shock
Pneumothorax
• Tension
– Blunt or penetrating
– Breath sounds
decreased or
absent
– Marked ventilatory
distress
– Hemodynamic
compromise
• Simple
– Blunt or penetrating
– Breath sounds
decreased or
absent
– Mild to moderate
ventilatory distress
– No hemodynamic
compromise
Pericardial Tamponade
• Penetrating mechanism most common
• Blood in pericardial sac:
– Compresses the heart
– Prevents adequate filling
– Thus, cardiac
output decreases
Blunt Cardiac Injury
• Direct injury to heart muscle
– May cause:
• Dysrhythmia
– Sinus tachycardia most common
• Right atrial or right ventricular rupture
• Valve rupture — rare
– New murmur
• Sudden death
Shock Management (1 of 14)
• Four questions guide prehospital
management:
– What is the cause of shock in this particular
patient?
• Hemorrhage is the most common
– What is the care for this type of shock?
– What can and should be done between now
and the time the patient reaches definitive
care?
– Where is the best place for the patient to get
definitive care?
Shock Management (2 of 14)
• Proper shock management
– Improves the oxygenation of RBCs
– Improves the delivery of RBCs to the tissues
• Airway
– What are the needs?
• Ventilation
– Does it require assistance?
Shock Management (3 of 14)
• Oxygenation
– Is it adequate?
• Circulation
– Hemorrhage controllable?
Shock Management (4 of 14)
• Patient positioning
– Supine
– Trendelenburg position no longer
recommended
• Allows the abdominal organs to push up on the
diaphragm and impede its movement
• No benefit in elevating lower extremities
Shock Management (5 of 14)
• Hemorrhagic shock
– Critical to stop ongoing blood loss and to
maintain perfusion
– Hemorrhage control
• External hemorrhage
• Internal hemorrhage
Every RBC counts!
Shock Management (6 of 14)
• Hemorrhagic shock (cont’d)
– External hemorrhage control
• Direct pressure will control most external
hemorrhage
• Tourniquet
• Immobilization of fractures
• Topical hemostatic agents (use to pack bleeding
wounds)
– Internal hemorrhage
• Controlled in the operating room
External Hemorrhage Control
Shock Management (7 of 14)
• Fluid therapy in hemorrhagic shock
– Balanced resuscitation
• Balance between how
much fluid is given
and how high the
BP is raised
• Excessive
resuscitation leads
to increased
bleeding
Shock Management (8 of 14)
• Patients with signs of hemorrhagic shock
– Maintain systolic BP at approximately
80–90 mm Hg
– If signs of traumatic brain injury are present,
maintain systolic BP at approximately
90–100 mm Hg
– Adult patients may require 1000–2000 ml of
warmed lactated Ringer’s solution or
normal saline
– Pediatric patients: 20 ml/kg bolus
Shock Management (9 of 14)
• Reassessment following fluid therapy
• Three responses:
– Rapid response
• Suggests that hemorrhage has stopped, may still
require surgery
– Transient response
• Significant blood loss and probably ongoing
hemorrhage, requires urgent surgery
– Minimal or no response
• Massive ongoing hemorrhage, requires immediate
surgery
Shock Management (10 of 14)
• Distributive (neurogenic) shock
– Must rule out hemorrhage as the primary
cause of shock
– Spine movement restriction (immobilization)
– Fluid administration
Shock Management (11 of 14)
• Cardiogenic shock in trauma
– Extrinsic
• Tension pneumothorax
– Needle decompression
• Pericardial tamponade
– Rapid transport
– Fluid administration
– Intrinsic
• Treat dysrhythmias as necessary
• Prevent fluid overload
Shock Management (12 of 14)
• Transport considerations
– Transport without delay to appropriate
destination
• Most procedures may be accomplished while en
route
– Maintain body temperature
• Cover patient after completing assessment
• Patient compartment temperature should be kept
as warm as possible
Shock Management (13 of 14)
• Prolonged transport
– Ensure airway and optimize ventilatory status
– Maintain external hemorrhage control
– Prevent body heat loss
– Reassess, reassess, reassess
Shock Management (14 of 14)
• Left untreated, shock progresses
• Prehospital care can affect outcome by
helping to restore perfusion and energy
production
• Managing shock in the prehospital setting
can help prevent the cascade of cell
death, organ death, and patient death
Minimizing Complications
(1 of 2)
• Assess for and recognize the signs of
shock
• Assume hemorrhagic shock until proven
otherwise
– Control external hemorrhage as rapidly as
possible
• Cardiac output and tissue oxygenation are
impaired early
Minimizing Complications
(2 of 2)
• Restore and maintain airway, ventilation,
oxygenation, and circulation
• Hypothermia creates a cycle of worsening
shock and hypothermia
• Transport without undue delay
Summary
• Shock is a state of cellular hypoperfusion,
leading to inadequate energy production to
meet metabolic needs
• The most common cause of shock in the
trauma patient is hemorrhage
• Shock is hemorrhagic until proven
otherwise
• The management of shock is aimed at
improving oxygenation of RBCs, improving
delivery of oxygenated RBCs to the
microcirculation, and controlling
hemorrhage
Questions?