Shock Categories Field Map

Why This Is Hard

Shock is inadequate tissue perfusion — not just “low blood pressure.” Patients can be in shock with a “normal” cuff reading while compensating with tachycardia and vasoconstriction. On the truck you must recognize shock early, guess the dominant category, and match interventions without locking into the wrong fluid or pressor path.

Mixed shock is real (trauma + sepsis, cardiogenic + distributive after ROSC). Categories are a teaching map, not a perfect label machine.

Four Buckets (Teaching Model)

1. Hypovolemic — not enough volume in the tank (blood loss, dehydration, burns).
2. Distributive — pipes too open / inflammatory vasodilation (sepsis, anaphylaxis, neurogenic).
3. Cardiogenic — pump failure (MI, severe cardiomyopathy, arrhythmia-driven failure).
4. Obstructive — blockage of flow (tension pneumothorax, tamponade, massive PE).

Field Clues by Category

Hypovolemic

• Bleeding (external or suspected internal), vomiting/diarrhea, poor intake, heat illness, burns.
• Flat neck veins (usually), cool pale skin, tachycardia, delayed cap refill; late hypotension.
• EMS theme: stop the bleed, limited scene time for trauma, volume replacement per protocol (crystalloid vs blood products).

Distributive

• Sepsis: infection source, fever or hypothermia, altered mentation, tachypnea — see sepsis lesson.
• Anaphylaxis: exposure, urticaria, wheeze, swelling, hypotension — epinephrine IM early per protocol.
• Neurogenic: high spinal injury context, warm dry skin below, bradycardia possible — careful fluids, other agents per protocol.

Cardiogenic

• Chest pain, ischemia history, wet lungs, JVD, cool clammy skin, pulmonary edema.
• EMS theme: cautious fluids (often small or none), treat rate/rhythm if causative, CPAP/nitrates when authorized and not hypotensive, destination for PCI as applicable.

Obstructive

• Tension pneumo: trauma/vent, unilateral findings, obstructive shock — decompress if authorized.
• Tamponade: penetrating chest classic; equal breath sounds, JVD, hypotension — rapid transport.
• Massive PE: sudden dyspnea/syncope, risk factors — supportive care, destination; thrombolysis only if protocol/medical control allows.

Street Map

1. Recognize shock — AMS, weak pulses, hypotension or compensated signs (tachycardia, cool skin, delayed cap refill), work of breathing, mottling, oliguria history.
2. Control life threats — airway/oxygen, massive bleed, tension pathway if indicated by protocol.
3. Categorize — volume, pipes, pump, or obstruction?
4. Match interventions to category and protocol — fluids are not universal; pressors are not universal; “just run it wide open” is not a plan.
5. Reassess — every intervention needs a before/after vitals and mentation check. Mixed shock exists.

Key Points for Paramedics

• Compensated shock can have a “normal” BP — look at the whole patient, especially kids and young adults.
• EtCO₂ may be low with poor perfusion — adjunct only, not a diagnosis by itself.
• Communicate category thinking: “Cardiogenic shock picture — cautious fluids per protocol, destination/PCI pathway as applicable.”
• Trend over single readings: one good BP after fluids does not mean the problem is solved.
• Keep the patient warm; hypothermia worsens coagulopathy and outcomes in trauma/shock education frameworks.

Field Pitfalls

• Flooding cardiogenic or obstructive shock with large fluid boluses.
• Missing anaphylaxis because there is no rash.
• Calling “stable” because BP is 100 systolic while mentation is crashing.
• Fixating on IV access while external hemorrhage is still uncontrolled.

Practice

For three recent calls (or scenarios), name the dominant shock bucket in one sentence and the first two interventions you would consider under your protocols. Related: Sepsis recognition, Massive hemorrhage first, Tension pneumothorax.

Sources & Further Study

• EMS shock teaching frameworks (hypovolemic, distributive, cardiogenic, obstructive).
• Your sepsis, anaphylaxis, trauma, and cardiogenic protocols.