SHOCK

 

INTRODUCTION 

Optimal patient care requires that the EMT-I understand the physiology of shock.  The following topics will be discussed during this lesson:

 

·          Review of the cardiovascular system

 

·          Pathophysiology of shock

 

·          Signs and symptoms of shock

 

·          Classifications of shock

 

·          Assessment of patients in shock

 

·          Field treatment and transport decisions for shock patients

 

LESSON OBJECTIVES

At the end of this lesson the participants will be able to:

 

1.               Identify the structure and function of the cardiovascular system.

 

2.               Define shock.

 

3.               Explain the shock mechanism and the body’s defense mechanisms.

 

4.               Describe the pathophysiology of hypovolemic, cardiogenic, and neurogenic shock.

 

5.               Recognize the signs and symptoms of shock.

 

6.               Discuss the proper method of assessing the patient in shock.

 

7.               Identify abnormal findings during the assessment of patients in shock.

 

8.               In a given situation, properly treat a patient in shock.

 

9.               In a given situation, be able to determine where the patient should be transported.

 

 

 

 

 

 

KEY VOCABULARY 

The following terms will be used during this lesson:

            •           Perfusion - blood flow into or through tissue.

 

            •           Shock - inadequate perfusion.

 

            •           PVR (Peripheral Vascular Resistance) - resistance to blood flow due to the peripheral blood vessels.

 

KEY CONCEPTS 

The following section provides information and space for taking notes on the key concepts discussed by the instructor.

 

REVIEW OF THE CARDIOVASCULAR SYSTEM

Heart (the “pump”)

·          Hollow muscular organ, which functions as a pump to circulate blood throughout the blood vessels.

 

·          Right side of the heart receives unoxygenated blood from the venous system and pumps it to the lungs where it exchanges oxygen and waste products.

 

·          Left side of the heart receives the oxygen enriched blood and pumps it to the organs and peripheral tissues via the arterial system.

 

·          Stroke Volume (SV):  Volume of blood ejected with each ventricular contraction; normal stroke volume = 60-130 ml

 

·          Heart Rate (HR):  Number of heart beats per minute

 

·          Cardiac Output (CO):  Amount of blood pumped by the heart in one minute; expressed in liters per minute (L/min)

·          Stroke volume x heart rate = cardiac output

·          SV x HR = CO

·          Example:  (SV) 70ml x (HR) 75/min = 532 ml/min or 5.3 L/min

 

Blood vessels (the “containers” or “pipes”)

·          Comprised of a complex network of veins, arteries, and capillaries.

 

·          Diameter of the smaller arteries is controlled by the sympathetic nervous system and determines the peripheral vascular resistance (PVR).

 

·          As the arterial vessels narrow, resistance to blood flow increases; conversely, the more they dilate the lower the resistance will be.

Blood pressure

 

·          Average pressure in the arteries throughout the cardiac cycle.

 

·          Depends on the elastic properties of the arterial walls and blood volume in the arterial system; therefore, it depends on the cardiac output and the peripheral vascular resistance.

 

·          Constantly regulated to maintain tissue perfusion during a wide range of conditions, i.e., exercise, change in position, change in blood volume, etc.

 

·          BP = CO x PVR

 

Blood (the “fluid”)

·          Delivers oxygen and nutrients to tissues; carries waste products away from tissues to be eliminated.

 

·          Cardiovascular system (a closed system) must contain an adequate volume of blood to fill its structures as well as supply an adequate amount of blood cells to assure oxygenation.

 

·          Normal circulating blood volume = 4.5 - 5 liters (L) or 70 ml/kg of body.

 

PATHOPHYSIOLOGY OF SHOCK

Shock

·          Inadequate perfusion or inadequate blood flow to body tissues.

 

·          Can lead to decreased cellular function and ultimately cell death.

 

·          Caused when any component of the cardiovascular system fails.

 

Compensatory mechanisms

The body attempts to compensate and restore perfusion by:

 

·          Increasing cardiac output

·          Stimulation of the sympathetic nervous system causes an increase in heart rate, stroke volume, and PVR.

 

·          Redistributing the circulating blood volume to vital organs

·          Vasoconstriction

·          Release of antidiuretic hormone (ADD) and renin to decrease urine production.

 

·          Increasing oxygen delivery to cells

·          Stimulation of sympathetic nervous system causes bronchodilation, increased respirations, and tidal volume.

 

 

 

SIGNS AND SYMPTOMS OF SHOCK

Early Stage (compensated shock): Compensatory mechanisms are able to maintain perfusion of vital organs

Heart Rate:  mild tachycardia; bounding pulse

 

Level of Consciousness:  lethargy, confusion, combativeness

 

Skin:  delayed capillary refill; cool and clammy

 

Blood Pressure:  normal or slightly elevated

 

Respirations: rapid and shallow
 
 

 

 

 

 

 

 

 

 

 

 


Middle Stage (uncompensated shock): Compensatory mechanisms are unable to maintain perfusion

Heart Rate:  moderate tachycardia; weak and thready pulse

 

Level of Consciousness:  confusion or unconsciousness

 

Skin:  delayed capillary refill; cold, clammy, and cyanotic

 

Blood Pressure:  decreased

 

Respirations: rapid and shallow
 
 

 

 

 

 

 

 

 

 

 

 


Late Shock

Heart Rate:  bradycardia; severe dysrhythmias

 

Level of Consciousness:  coma

 

Skin:  pale, cold, marked diaphoresis

 

Blood Pressure:  marked hypotension

 

Respirations: decreased rate and tidal volume
 
 

 

 

 

 

 

 

 

 

 

 


CLASSIFICATIONS OF SHOCK

•        Hypovolemic

•        Cardiogenic

•        Neurogenic

•        Anaphylactic

•        Septic
 
 

 

 

 

 

 


Hypovolemic Shock

 

 

 

 

•        Pathophysiology: Inadequate blood volume

 

•        Causes:

•        Hemorrhage (internal or external)

•        Acute dehydration (diarrhea, vomiting, shifting of fluids out

     of the vascular space due to burns, diabetic ketoacidosis, etc.)
 

Field Management

•        BLS Procedures

•        Control bleeding

•        High flow oxygen

•        Shock position (consider Trendelenburg position for suspected spinal injury without head trauma)

•        Assist with ALS procedures

 

•        ALS Procedures

•        Advanced airway PRN

•        Monitor

•        Venous access

•        Fluid resuscitation

•         
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Cardiogenic Shock

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Field Management

•        BLS Procedures

•        High-flow oxygen

•        Shock position

•        Assist with  ALS

 

•        ALS Procedures

•        Advanced airway PRN

•        Monitor

•        Venous access

•        Consider fluid challenge (monitor lung sounds)

•        Dopamine PRN

•        Dysrhythmias; cardioversion or medications such as Lidocaine, Adenosine, or Atropine PRN

•        Tension pneumothorax; needle thoracostomy PRN
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Neurogenic Shock

•        Pathophysiology

•        Vasomotor paralysis below the level of the injury resulting in decreased peripheral vascular resistance

•        Sympathetic impulses which would normally stimulate vasoconstriction are interrupted, leading to widespread vasodilation

•        Blood collects in the capillary beds reducing venous return, cardiac output, and blood pressure

 

•        Causes

•        Severe spinal cord injury or total transection

•        Central nervous system injury
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Additional Signs and Symptoms

•        Skin often flushed and warm, rather than pale; this type of shock is also know as “dry shock”

 

•        Typically, heart rate does not increase due to loss of sympathetic impulses
 

Field Management

•        BLS Procedure

•        High-flow oxygen

•        Spinal immobilization

•        Consider Trendelenburg position if no head trauma

•        Assist with ALS Procedures

 

•        ALS Procedures

•        Advanced airway PRN (using manual in-line axial immobilization)

•        Monitor

•        Venous access

•        Consider fluid challenge (monitor lung sounds)

•        Dopamine PRN

•        Consider Atropine for bradycardia with hypotension
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Anaphylactic Shock (Severe Allergic Reaction)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Septic Shock

GOLDEN RULE:

The greatest chance for survival is early recognition and treatment

of shock.
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


INITIAL ASSESSMENT AND FOCUSED HISTORY AND DETAILED PHYSICAL EXAMINATION OF THE PATIENT IN SHOCK

 

Initial Assessment

1) Assess Environment:  (may need to manipulate the environment)

  • Safety of rescuers and environment
  • Environmental Factors
    • Patient Location (home, street, convalescent, etc.)
    • Weapons (may indicate trauma mechanism)
    • Medications (may offer clues to past medical history)
    • Witnesses (may help to explain circumstances)

·        Mechanism of Injury

·        Number of Patients
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3)  Breathing:  assess for rate and quality of breathing; assess lung           sounds during the primary assessment for trauma patients

•        ­ respirations and tidal volume- early or middle stage of shock

•        ― respirations and tidal volume- irreversible shock; or potential spinal or brainstem injury

•        Abnormal lung sounds: For trauma patients assess for unequal or absent lung sound to determine the presence of a tension pneumothorax

 
 

4)  Circulation:  assess for uncontrolled external bleeding and apply         direct pressure PRN; assess rate, character, and location of               pulses

•        ­ heart rate- early or middle shock

•        ― heart rate- irreversible shock; or may be present in neurogenic shock

•        Character of pulse, i.e. weak or strong, provides  estimate of pressure and volume within the arteries

•        Skin- pale, cool, moist skin and delayed capillary refill due to peripheral vasoconstriction;  cyanosis indicates lack of oxygenated blood
 

2)  Airway: (determine responsiveness and patency of airway)

·        Patients may be altered or unconscious and unable to protect   or maintain their airway.

 
 

5) Skin Signs:   assess color, temperature, and moisture

·        Pale, cool moist skin and delayed capillary refill are due to peripheral casoconstriction

·        If signs of poor perfusion, consider placing patient supine
 

6) Assess Neurological Status:

  • Restlessness, agitation, confusion or lethargy due to hypoxia and decreased cerebral perfusion
  • Unconsciousness or coma due to prolonged hypoxia and cell death
 

7) Determine Chief Complaint
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Focused History and Detailed Physical Examination

 

1) Elicit history of chief complaint or problem

  • Helps to determine potential cause of shock or which component of the cardiovascular system has failed
  • Determining the cause of shock will guide field management
  • See section of “Classification of shock” to determine pertinent information that should be obtained during a focused history
 

2) Elicit personal history (HAM)

  • H         medical history/under a doctors care
  • A         allergies/age
  • M         medications-current over the counter & prescription
 

3) Vital Signs:

•        Between 30-40% of the blood volume must be lost before the systolic blood pressure drops below normal range

•        The BP is not a reliable indicator of early shock; assess for subtle signs, i.e. delayed capillary refill, ­ heart rate and respiratory rate, and an altered LOC

•        Consider orthostatic vital signs with suspected volume depletion: do not perform if other injuries or the patient’s general condition makes it unsafe to obtain

•        Cardiac dysrhythmias can cause shock or be a complication of shock due to hypoxia, acidosis, and an increase in circulating catecholamines
 

GOLDEN RULE:

Frequent reassessments must be done enroute since the patient’s condition can deteriorate rapidly.
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Considerations for BLS Transport

 

 

 

5) Pertinent Body Check:

  • Medical or minor trauma – perform body check pertinent to chief complaint
  • Major trauma – perform total body check

 
 

Head to Toe Examination

•        Shock, typically, is not the result of isolated head injuries, look for additional injuries

•        Assess for abnormal lung sounds:

•        rales- pulmonary edema due to pump failure; fluid overload due to fluid challenges

•        wheezes- bronchoconstriction due to an allergic reaction

•        Neurogenic shock may present with warm, dry, pink skin and a normal or low pulse

•        Anaphylactic shock can present with a rash, hives, and wheezing

•        Septic shock can present with either cool or hot skin
 

4) Special Questions:

  • Ask questions specific to chief complaint