Shock — review sheet
Everything from the hour, in the order we did it. Nothing here is a substitute for your protocol.
Shock is inadequate perfusion — not enough oxygenated blood reaching tissue to meet what that tissue needs right now. It is not a blood pressure. A normal blood pressure does not rule shock out, and a low one is a late finding.
The model: pump, pipes, fluid
Three things have to be right for perfusion. Each kind of shock is one of them failing — plus one where something physically gets in the way.
- Pump — a heart strong and fast enough (but not too fast) to move blood forward.
- Pipes — vessels that squeeze and relax to hold pressure and direct flow.
- Fluid — enough blood in the system, carrying enough haemoglobin to matter.
What you see first is the body fighting back
| The body does | Because | So you see |
|---|
| Heart speeds up | Move remaining blood faster | Tachycardia — usually the first sign in an adult |
| Vessels clamp down | Protect brain and heart; sacrifice skin and gut | Cool, pale, damp skin; slow cap refill |
| Diastolic rises | The squeeze shows up as the bottom number | Narrowing pulse pressure |
| Breathing speeds up | Blow off the acid the cells are making | Tachypnoea, often early |
| Brain gets less | Even a defended brain notices | Anxious, restless, repetitive — then drowsy |
Compensated = perfusion signs present, pressure still held. In an adult this can last hours. Uncompensated = the pressure has fallen; can progress to arrest in minutes. In a child, hypotension is late and ominous — a tachycardic child may already be close to collapse.
One tool that beats memorising thresholds
HR > SBP
If the pulse number passes the top blood-pressure number, treat that patient as badly hurt. No arithmetic.
| Age | Systolic threshold |
|---|
| 10–64 | Under 90 |
| 65 and over | Under 110 |
| 0–9 | Under 70 + (2 × age in years) |
Exam noteAn 80-year-old with a systolic of 100 meets a RED trauma-triage criterion. Many textbooks teach one adult number — 90 — which misses the geriatric patient entirely.
The four kinds
Hypovolemic — not enough fluid
Blood out (trauma, GI bleed, ectopic, pelvis, femur) or fluid out (vomiting, diarrhoea, burns, heat, uncontrolled diabetes).
- Cool, pale, damp skin
- Fast, weak, thready pulse
- Narrowing pulse pressure; delayed cap refill
- Flat neck veins
The one that gets missed: a pelvis or abdomen can hold a patient's entire blood volume with nothing showing outside. If the mechanism could bleed and the skin says shock, believe the skin.
Distributive — the pipes opened up
Enough fluid; it's in the wrong place. Often warm, flushed, dry skin with fast cap refill and bounding pulses — the opposite of what you expect.
- Septic — fever or hypothermia, new confusion, an indwelling line or catheter. New confusion in an older adult with infection is sepsis until proven otherwise.
- Anaphylactic — exposure plus airway plus circulation. Up to a fifth have no rash. Keep them supine unless breathing demands sitting; don't stand them up.
- Neurogenic — cord injury above roughly T6 cuts sympathetic outflow. Warm, dry, and unable to speed the heart up.
A hypotensive trauma patient with a spinal injury is bleeding until you prove otherwise. He cannot mount the tachycardia that would warn you.
Spinal shock ≠ neurogenic shock. Spinal shock is neurological (motor, sensory, reflex loss below the lesion). Neurogenic shock is circulatory (loss of vascular tone). Spinal shock isn't a shock state at all.
Exam noteYour book teaches hypotension + bradycardia = neurogenic shock. Know it for the test. In practice the classic picture was present in only 19.3% of cervical cord injuries on ED arrival (Guly 2008, n=490). Its absence rules nothing out, and its presence never rules out haemorrhage.
Cardiogenic — the pump is failing
Forward flow fails, so everything backs up behind the pump.
- Cool, grey, sweaty skin
- Crackles in both lung fields
- Distended neck veins; can't lie flat
- Chest pain, cardiac history, ankle swelling if chronic
Why it changes what you do: this is the shock where filling the tank makes things worse. Deteriorates after fluid, or develops crackles → think pump, and stop. A flooded left ventricle can also wheeze — it isn't always asthma.
Obstructive — something is in the way
Pump and pipes work; a mechanical obstruction stops blood getting back to or out of the heart. Breath sounds tell you which:
- Tension pneumothorax — absent breath sounds on one side, rising work of breathing, a mechanism.
- Cardiac tamponade — JVD with clear breath sounds, muffled heart sounds, narrow pulse pressure, penetrating chest wound.
- Pulmonary embolism — sudden dyspnoea, clear lungs, marked hypoxia. Look at the legs; ask about surgery and immobility.
Exam noteYour book teaches the triad — absent breath sounds, JVD, tracheal deviation. Know it for the test. Those findings largely come from ventilated patients; in patients breathing on their own, hypoxia was present in only 50% (Roberts 2015, Ann Surg). Don't wait for the triad. And flat neck veins do not rule out a tension pneumothorax — you can't distend veins you've already emptied by bleeding.
The fifth category most books drop
The NASEMSO national model guidelines list a fifth: combined — one form causing another. That's exactly where single-finding rules break. When the findings disagree with each other, suspect two problems, not one wrong finding.
What you actually do
- Fix airway and breathing first.
- Stop obvious bleeding: direct pressure → wound packing → tourniquet if pressure fails or isn't practical.
- Oxygen to a target — 94–98%. In known COPD, going above 92% is rated potentially harmful.
- Keep them supine and keep them warm. A cold patient doesn't clot; blankets are treatment.
- Leave early. Transport is the intervention.
Positioning: supine. If there's no trauma, raising the feet 6–12 inches may be reasonable while you wait — put them flat again if it makes them worse. Injured patient: leave them how you found them.
Tourniquet aftercare: tighten until bleeding stops and the distal pulse is gone. Mark the time on the patient and the report. Keep it visible. Treat the pain — never loosen it for discomfort. Still bleeding? A second tourniquet goes above the first.
Montana scope
Base EMT: epinephrine auto-injector, aspirin for suspected ischaemic chest pain, direct pressure / wound packing / tourniquet, oxygen and airway management.
With an endorsement: the Medication Endorsement allows epinephrine drawn up and given IM, 1:1,000 — adult only. A separate IV/IO Initiation Endorsement allows intravenous access, which the national model does not grant at EMT level at all.
Verify thisEndorsements are per-provider and per-service — confirm yours with your medical director. The rules moved from ARM 24.156 to ARM 24.112 on 1 January 2026, so an older handout cites a renumbered rule.
On the adult epinephrine dose: the allergy bodies (AAAAI/ACAAI, WAO) give a maximum of 0.5 mg for an adult; the NASEMSO EMS model guideline gives 0.3 mg for patients 25 kg and over. Both are current. Your service protocol decides — follow that number.
Three traps
- A normal blood pressure. Shock is a perfusion problem. Pressure is the last thing to fall — and in a child it falls almost at the end.
- Waiting for the classic picture. Neurogenic shock shows it in a minority; tension pneumothorax rarely gives the full triad. Treat the pattern, not the checklist.
- One number for everybody. Under 90 for ages 10–64, but under 110 from 65 up — and HR above SBP at any adult age.
Exam note“Psychogenic shock” appears in EMT textbooks but in none of the National EMS Education Standards, the NASEMSO guidelines, or the classification literature. What it describes is vasovagal syncope — it corrects itself once the patient is horizontal. Know the term for the test; don't build a category around it.
Practise it
Twenty cases, no timer, no score shown to anyone but you.
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Sources
All verified 28 August 2026. Public sources only.
- National EMS Education Standards, NHTSA, 2021 (amended 24 Feb 2025)
- National EMS Scope of Practice Model, NHTSA, 2019 + Change Notices 1.0 and 2.0 (Aug 2021)
- NASEMSO National Model EMS Clinical Guidelines v3.0, March 2022 (adopted by Montana, Oct 2024)
- 2024 AHA / American Red Cross Guidelines for First Aid, Circulation 2024
- National Guideline for the Field Triage of Injured Patients, 2021/22
- Surviving Sepsis Campaign 2026, Intensive Care Medicine 52:863–936 (23 March 2026)
- Guly HR, Bouamra O, Lecky FE. Resuscitation 2008;76(1):57–62
- Roberts DJ, Leigh-Smith S, Faris PD, et al. Annals of Surgery 2015;261(6):1068–78
- Montana DLI ECP Scope of Practice Document and EMT Medication Endorsement list; MAR Notice 2025-149
- NREMT EMT Examination Specifications (exam launched Spring 2025)
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