Emergency Care and Transportation of the Sick and Injured: Chapter 12 - Shock

Emergency Care and Transportation of the Sick and Injured: Chapter 12 - Shock

This chapter discusses the topic of shock, characterized as a state of collapse and failure of the cardiovascular system, leading to inadequate circulation of blood. Shock can be precipitated by various medical conditions or traumatic events, and it requires immediate recognition and treatment.

Introduction to Shock

Shock, or hypoperfusion, signifies a condition of collapse within the cardiovascular system.

• In the earliest stages, the body's physiological response is to maintain homeostasis.

• Shock can arise from either medical or traumatic incidents, emphasizing its importance in emergency medical care.

Pathophysiology of Shock

Overview

• Adequate perfusion is essential to deliver oxygen and nutrients to cells while allowing the removal of waste products. Any compromise in perfusion can result in cellular injury or death.

• If perfusion is impaired, transportation of carbon dioxide away from tissues is hindered, which can lead to dangerous accumulations of waste products.

Critical Components of the Cardiovascular System

• The cardiovascular system comprises three key parts:

  1. Pump: Heart

  2. Set of Pipes: Blood vessels or arteries

  3. Contents: The blood

• Collectively, these parts form what is known as the “perfusion triangle.” When shock is present, one or more of these components may malfunction.

Blood Pressure and Perfusion

• Blood pressure represents the pressure exerted by blood within vessels at any given moment and includes two measurements:

  • Systolic Pressure: The peak pressure during heartbeats

  • Diastolic Pressure: The pressure in arteries when the heart is at rest between beats

• The pulse pressure is the numerical difference between systolic and diastolic pressures.

• Blood flow through capillary beds is modulated by capillary sphincters, which are under the control of the autonomic nervous system and respond to stimuli including temperature and metabolic needs for oxygen and waste removal.

Requirements for Adequate Perfusion

• Perfusion of tissues necessitates:

  • Efficient oxygen exchange in the lungs

  • Sufficient nutrients (like glucose) in blood

  • Effective waste removal primarily facilitated through the lungs

• The body has mechanisms, chiefly involving the autonomic nervous system and hormones, to support vital organ perfusion during states of increased need.

• When blood pressure is perceived to fall, hormones trigger numerous compensatory responses, including:

  • Increased heart rate

  • Enhanced strength of cardiac contractions

  • Peripheral vasoconstriction to maintain blood flow to vital organs

Causes of Shock

Types of Shock

The fundamental causes of shock are categorized into three groups:

1. Pump Failure:

   • Examples include heart attack, trauma to the heart, and obstructive causes such as large pulmonary embolus.

2. Poor Vessel Function:

   • Causes encompass infections, drug overdoses (e.g. narcotics), spinal cord injuries, and anaphylaxis.

3. Low Fluid Volume:

   • Commonly caused by trauma to blood vessels or tissues and fluid loss from the gastrointestinal tract due to vomiting or diarrhea.

Specific Types of Shock

• Cardiogenic Shock:

  • Results from the heart’s inability to function adequately, often leading to pulmonary edema due to blood backup into the lungs.

• Obstructive Shock:

  • Causes include mechanical obstructions such as cardiac tamponade, tension pneumothorax, and pulmonary embolism.

• Distributive Shock:

  • Results from widespread dilation of small arterioles or venules, pooling blood, with subtypes including:

  • Septic Shock

  • Neurogenic Shock

  • Anaphylactic Shock

  • Psychogenic Shock

• Hypovolemic Shock:

  • Indicates inadequate fluid volume in the circulatory system, often linked to significant internal or external hemorrhaging.

Respiratory Insufficiency and Shock

• Conditions like severe chest injuries or airway obstructions may inhibit oxygen intake. Anemia also contributes to tissue hypoxia due to insufficient red blood cells for adequate oxygen delivery. Additionally, exposure to toxins such as carbon monoxide or cyanide can impair cellular oxygen metabolism.

The Progression of Shock

Stages of Shock

• Shock progresses through identifiable stages:

1. Compensated Shock:

   • The body maintains perfusion despite an initial drop in perfusion pressure.

2. Decompensated Shock:

   • Marks when compensatory mechanisms fail, resulting in significant perfusion deficits.

3. Irreversible Shock:

   • This stage indicates profound systemic failure, where recovery is extremely unlikely.

• Notably, blood pressure is often one of the last measurable indicators to change. A decrease in blood pressure typically means shock has advanced considerably, particularly in infants and children.

Signs to Anticipate Shock

• In emergency scenarios, the anticipation of shock should occur if the patient presents with conditions such as:

  • Multiple severe fractures

  • Significant abdominal or chest injuries

  • Spinal injuries

  • Severe infections

  • Major heart attacks

  • Anaphylaxis

Scene Size-Up

• Ensure the presence of law enforcement in violent incidents and look for evidence pertaining to the mechanism of injury (MOI) or nature of illness (NOI).

Primary Assessment

Steps in Primary Assessment

• Conduct a rapid exam, determining the patient’s consciousness level and identifying life-threatening concerns.

• Establish patient priority for transport.

• Administer high-flow oxygen to assist with perfusion in cases of hypoperfusion and ensure rapid transport.

• Request advanced life support (ALS) as needed.

Continued Assessment

• Form a general impression and assess the patient’s airway and breathing status. Verify circulatory integrity.

• Immediately identify and manage life-threatening bleeding.

• Make decisions regarding patient urgency and necessary transport facilities.

History Taking

• Gather relevant information about the chief complaint and apply the SAMPLE technique to collect patient history.

Secondary Assessment

• This entails a repeat of primary assessment, followed by a focused examination. Life-threatening issues discovered must be treated without delay, and a complete set of baseline vital signs should be acquired.

Reassessment

Steps in Reassessment

• Continuously reassess vital signs, interventions performed, chief complaints, airway-breathing-circulation (ABCs), and mental status.

• Evaluate what further interventions are required, emphasizing cardiovascular support and early, aggressive treatment for shock through oxygen provision and warmth.

Emergency Medical Care for Shock

Treatment Protocol

• Immediate treatment is essential upon shock recognition. The standard precautions should be adhered to, ensuring all visible external bleeding is controlled and airways are clear.

• Manual in-line stabilization may be necessary, and ongoing monitoring of breathing and pulse is critical.

• Provide comfort to the patient while reassuring them, and withhold any food and drink until a physician evaluates them.

• If spinal immobilization is needed, lay the patient on a backboard and supply oxygen while tracking their oxygenation levels.

• Keep the patient warm with blankets and document vital signs every five minutes during treatment and transport.

Specific Treatments for Different Types of Shock

• Cardiogenic Shock:

  • The heart's impairment precludes effective pumping of blood. Patients should be placed in a position of comfort, and transport initiated swiftly, avoiding nitroglycerin in hypotensive patients.

• Obstructive Shock:

  • Prioritize increasing cardiac output, applying high-flow oxygen, recognizing that surgery is the definitive treatment. In cases of tension pneumothorax, chest decompression is necessary, with ALS consultation and rapid transport.

• Septic Shock:

  • Hospital management is critical, utilizing standard precautions while administering high-flow oxygen and ventilatory support as necessary, using blankets to maintain body heat.

• Neurogenic Shock:

  • Emergency treatment encompasses maintaining a clear airway, spinal immobilization, aiding inadequate breathing, conserving body heat, and ensuring optimal circulation.

• Anaphylactic Shock:

  • Administer epinephrine and ensure timely transport while providing oxygen and ventilatory assistance during transit. Anaphylactic symptoms may worsen rapidly, emphasizing the need for rapid ALS support.

• Psychogenic Shock:

  • In uncomplicated fainting cases, restoring blood circulation while horizontal typically resolves the issue. Monitor for injuries if the patient falls and suspect additional problems if they report inability to walk after such an event.

• Hypovolemic Shock:

  • Control external bleeding, maintain warmth, and recognize signs of internal bleeding, providing aggressive support. Ensure airway security and respiratory therapy, with rapid transportation prioritized.

• Respiratory Insufficiency:

  • Secure and clear the airway, provide ventilations as necessary, and administer supplemental oxygen promptly after stabilization.

• Treating Older Patients:

  • Acknowledge that older patients may have severe complications, and understand that their typical medications may obscure or replicate shock symptoms. Management procedures remain consistent regardless of age.

Review Questions

Definitions and Concepts

1. Shock is most accurately defined as cardiovascular collapse leading to inadequate perfusion (Answer: B). While it may result in reduced oxygen supply, it is not a definition of shock itself.

2. Anaphylactic Shock is associated with urticaria (Answer: A); it results from allergic reactions typically marked by severe respiratory distress and hypotension.

3. Warning signs of compensated shock include restlessness, pale cool clammy skin, and other anxiety-related signs, whereas weak or absent peripheral pulses indicate advanced state (least likely occur) (Answer: D).

4. For a trauma patient in shock, prioritize interventions that ensure spinal stabilization, oxygen provision, and rapid transport over splinting fractures (Answer: C).

5. In cardiogenic shock, major influental factors encompass inadequate heart function, tissue disease, and electrical system malfunction; however, severe bacterial infection is not a contributing factor (Answer: C).

6. A patient presenting with BP 80/60 mm Hg and symptoms of sepsis—such as mottled skin and fever—is most likely experiencing septic shock (Answer: A).

7. In neurogenic shock, the LEAST likely symptom is tachycardia as compromised nerves prevent the sympathetic system's reflex control (Answer: C).

8. For a patient whose abdomen rigidity indicates probable internal bleeding, response should focus on treating for hypovolemic shock, prioritizing systemic support over diagnosing specific abdominal injuries (Answer: D).

9. Anaphylactic shock patients with generalized rashes and hypotension need prompt epinephrine administration after securing oxygenation (Answer: A).

10. Potential causes of impaired tissue perfusion excluded the increased number of red blood cells which would indeed enhance delivery of oxygen and nutrients (Answer: A).

In all cases, recognizing the signs and implications of shock are paramount in treatment protocol adherence and ensuring patient safety and recovery.