Shock is inadequate tissue perfusion, often but not always with hypotension. Look at the three windows (skin, kidney, brain) and lactate, then use history, examination and POCUS to sort it into hypovolaemic, distributive, cardiogenic or obstructive.
At the bedside
Timed steps- 1
Look at the three windows
0-5 minSkin: cold, mottled, capillary refill > 3 s. Kidney: urine < 0.5 mL/kg/h. Brain: confusion, agitation, drowsiness.
- 2
Measure
0-5 minMAP (not just SBP), heart rate, shock index (HR/SBP > 0.9-1 is abnormal), SpO2, temperature, lactate (VBG is fine).
- 3
Start resuscitation while you think
0-10 minO2, two large-bore cannulae, monitor, 500 mL crystalloid bolus unless overt pulmonary oedema, vasopressor early if MAP < 65 with diastolic < 40-50 mmHg.
- 4
Classify with VIP + POCUS
0-15 minHistory and exam (bleeding, infection, chest pain, anaphylaxis, trauma). RUSH-style POCUS: pump (LV, RV, pericardium), tank (IVC, lungs, FAST, aorta), pipes (aorta, DVT).
- 5
Treat the cause
15-60 minSource control and antibiotics (septic); haemorrhage control (hypovolaemic); PCI or MCS (cardiogenic); thrombolysis, pericardiocentesis, decompression (obstructive); adrenaline IM (anaphylaxis).
- 6
Arterial line and reassess
OngoingArterial line once on vasopressors; reassess perfusion, lactate every 2 h, and fluid responsiveness before each further bolus.
Four types of shock: bedside pattern
| Type | Common causes | Skin / JVP | POCUS clue | Haemodynamics (CO / SVR / filling) |
|---|---|---|---|---|
| Hypovolaemic | Haemorrhage, GI loss, burns, DKA | Cold / flat | Small hyperdynamic LV, collapsing IVC | ↓ / ↑ / ↓ |
| Distributive | Sepsis, anaphylaxis, spinal cord injury, adrenal crisis, liver failure | Warm early / flat or normal | Hyperdynamic LV, normal or small IVC | ↑ or normal / ↓ / ↓ or normal |
| Cardiogenic | MI, myocarditis, cardiomyopathy, valve failure, arrhythmia | Cold / raised | Poor LV, B-lines, plethoric IVC | ↓ / ↑ / ↑ |
| Obstructive | PE, tamponade, tension pneumothorax, severe LVOT obstruction | Cold / raised | Dilated RV (PE), effusion with RA/RV collapse, absent lung sliding | ↓ / ↑ / ↑ (right) |
Mixed shock is common (for example septic shock with septic cardiomyopathy).
Calculators for this topic
References
Undifferentiated shock
Step 1 of ~5
ABC, O2, IV access, lactate, ECG, monitor
Based on Vincent JL, De Backer D; Cecconi M, De Backer D, Antonelli M, et al. Educational use; follow local protocol.
Pathophysiology
Oxygen delivery DO2 = CO × CaO2 (CaO2 ≈ 1.34 × Hb × SaO2). Shock is a mismatch between DO2 and VO2. Early on, the tissues extract more oxygen (ScvO2 falls). When extraction is maximal, anaerobic metabolism and lactate rise. In distributive shock, microcirculatory shunting can cause tissue hypoxia even with a normal or high cardiac output.
Evidence
- The ESICM 2014 consensus defines shock clinically with lactate > 2 mmol/L, recommends a MAP of ≥ 65 mmHg initially, does not require hypotension, and recommends echocardiography to identify the type of shock.
Controversies
- Individualised MAP targets in chronic hypertension (SEPSISPAM subgroup had less renal replacement therapy with a higher MAP).
🇮🇳 India notes
- Many patients present late to Indian tertiary centres after transfer, already on dopamine started at a referring hospital; switch to noradrenaline.
- Tropical infections (dengue, leptospirosis, scrub typhus, malaria) cause mixed distributive and capillary-leak shock; see module 25.
References
Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.