TOPIC 38: Shock – Manage Different Types of Shock

MOCA-PBR – 2025 Edition TOPIC 38: Shock – Manage Different Types of Shock

OFFICIAL ABP TOPIC:

Manage different types of shock

BACKGROUND

Shock is a life-threatening condition characterized by significantly reduced tissue perfusion. This impairs oxygen delivery to vital organs and leads to a buildup of metabolic waste products like lactic acid. Prompt recognition and categorization of shock are critical for effective management.

CLASSIFICATION OF SHOCK

There are four main categories of shock, each caused by a different underlying problem:

Hypovolemic Shock: Decreased preload (blood returning to the heart) due to volume loss from bleeding, diarrhea, etc.
Distributive Shock: Abnormal dilation of blood vessels leads to very low systemic vascular resistance and low blood pressure, as in sepsis and anaphylaxis.
Cardiogenic Shock: The heart muscle is not contracting strongly enough to maintain adequate blood flow to organs. This can be due to a congenital heart defect, arrhythmia, infection, or medication poisoning.
Obstructive Shock: Blood flow is physically obstructed so the heart can’t push blood forward effectively. Tension pneumothorax, cardiac tamponade, and large pulmonary embolism are examples.

CLINICAL FEATURES BY TYPE OF SHOCK

SHOCK TYPE	CLINICAL FEATURES
Hypovolemic Shock	– History of fluid losses (e.g., diarrhea, vomiting, hemorrhage) – Dry mucous membranes – Tachycardia – Flat neck veins
Distributive Shock	– Low systemic vascular resistance – Warm extremities – Bounding pulses – Associated with sepsis or anaphylaxis
Cardiogenic Shock	– Gallop rhythm – Hepatomegaly – Pulmonary edema – Jugular venous distension – Cyanosis unresponsive to oxygen
Obstructive Shock	– Signs of tension pneumothorax (absent breath sounds, hyperresonance) – Cardiac tamponade (muffled heart sounds) – Massive pulmonary embolism (chest pain, dyspnea)

EVALUATION OF SHOCK

Promptly recognizing shock is critical to starting treatment early. Look for altered mental status, weak peripheral pulses, and prolonged capillary refill. Hypotension is a late finding; shock may present with a normal BP. Assess Airway, Breathing, Circulation (ABCs). Ensure the patient has a patent airway, is ventilating adequately, and has vascular access established. Address any compromise immediately.

FOCUSED PHYSICAL EXAM

Check vital signs to assess for fever, hypothermia, tachycardia, hypoxia, tachypnea, hypotension.
Assess perfusion (skin color/warmth, capillary refill), pulse quality, and mental status.
Look for signs of dehydration like dry mucous membranes and poor skin turgor.
Evaluate work of breathing; auscultate for wheezing, crackles, or absent breath sounds.
Listen for murmurs/gallops; check for neck vein distension and hepatomegaly.

TARGETED DIAGNOSTICS

Bedside glucose to rapidly identify hypoglycemia.
Continuous cardiac monitoring and pulse oximetry.
Labs: ABG or VBG, lactate, CBC, blood culture, electrolytes, and coagulation studies.
Imaging: CXR for cardiopulmonary processes, point-of-care US for IVC collapsibility, pneumothorax, and cardiac function.
Specialized studies like echocardiogram as indicated.

MANAGEMENT OF SHOCK

INITIAL STABILIZATION

The first priority is supporting the ABCs and treating immediately reversible causes of shock:

Airway: Provide oxygen, position to protect the airway, and prepare to intubate if there are signs of impending respiratory failure.
Breathing: Initiate bag-valve-mask ventilation or mechanical ventilation in those with apnea, hypoventilation, or severe work of breathing.
Circulation: Establish IV/IO access.
1. If hypotensive, push isotonic crystalloid 20 mL/kg boluses every 5–10 minutes.
2. If normotensive, give 10–20 mL/kg over 15–20 minutes. Reassess perfusion after each bolus.
Emergencies: Perform needle thoracostomy for suspected tension pneumothorax, pericardiocentesis for tamponade, or IM epinephrine for anaphylaxis.

PROVIDING IV FLUIDS FOR DIFFERENT TYPES OF SHOCK

SHOCK TYPE	FLUID VOLUME AND RATE	CAUTIONS
Hypovolemic Shock	– 20 mL/kg bolus of isotonic crystalloid (e.g., normal saline, Ringer’s lactate) over 5-10 minutes – Repeat as needed	– None
Distributive Shock	– Up to 60-100 mL/kg aggressively	– Monitor for fluid overload
Cardiogenic Shock	– 5-10 mL/kg bolus over 15-30 minutes	– Avoid large volumes – Use inotropes early
Obstructive Shock	– Cautious boluses only as needed for stabilization	– Address obstruction (e.g., tamponade) first

ONGOING MANAGEMENT

Further interventions depend on the type of shock and response to initial therapy:

SHOCK TYPE	KEY INTERVENTIONS
Hypovolemic Shock	– Replace fluids with crystalloids – Control bleeding (if hemorrhagic) – Transfuse blood products as needed (children with hemorrhagic shock who do not respond to 40-60 mL/kg of crystalloid should receive blood next)
Distributive Shock	– Sepsis: Aggressive fluids, epinephrine or norepinephrine for refractory shock, antibiotics, consider stress-dose corticosteroids if not improving – Anaphylaxis: Epinephrine, antihistamines
Cardiogenic Shock	– Careful fluid administration – Use inotropes like dobutamine or milrinone to support cardiac output – Manage arrhythmias – Consult with cardiology
Obstructive Shock	– Relieve obstruction: Needle decompression for pneumothorax, pericardiocentesis for cardiac tamponade, antithrombotic therapy or thromboembolectomy for pulmonary embolism, prostaglandin E1 infusion for ductal-dependent congenital heart defects

Continuously reassess to titrate interventions and ensure shock is resolving:

Mental status should improve to normal alertness.
Continuous cardiac monitoring and pulse oximetry.
Capillary refill should shorten to <2 seconds.
Peripheral pulses should feel strong and equal to central pulses.
Blood lactate levels should improve.
Urine output should be >1 mL/kg/hour.

REFERENCES

https://www.uptodate.com/contents/shock-in-children-in-resource-abundant-settings-initial-management

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