AKT · Cardiovascular/Circulation & blood pressure

Shock

Circulatory failure → inadequate tissue perfusion and cellular hypoxia

Overview

A life-threatening state of inadequate tissue perfusion. The classification drives treatment: hypovolaemic (haemorrhage/fluid loss), cardiogenic (pump failure — MI, arrhythmia), obstructive (PE, tamponade, tension pneumothorax), and distributive (sepsis, anaphylaxis, neurogenic). Recognising the type — especially separating cardiogenic/obstructive from the rest — is essential because fluids help some and harm others.

Recognise

Hypotension, tachycardia, prolonged capillary refill, oliguria, altered mental state, raised lactate
Type-specific signs: cool/clamped (hypovolaemic, cardiogenic), warm/vasodilated (early septic, anaphylaxis, neurogenic), raised JVP (cardiogenic/obstructive)
Anaphylaxis: urticaria/angioedema + airway/breathing compromise; tension pneumothorax: tracheal deviation; tamponade: Beck's triad

Red flags

Cardiogenic or obstructive shock (raised JVP) — aggressive fluids can worsen it → treat the obstruction/pump cause
Anaphylaxis → IM adrenaline immediately; tension pneumothorax → needle/finger decompression; tamponade → pericardiocentesis

Differentials & how to tell them apart

Hypovolaemic shockbleeding/fluid loss, empty veins, responds to fluids/blood

Cardiogenic shockpump failure, raised JVP, pulmonary oedema — fluids harm

Obstructive shockPE/tamponade/tension pneumothorax — treat the obstruction

Distributive (septic/anaphylactic/neurogenic) shockvasodilated, warm peripheries early

Investigations

Identify the type clinically; bloods incl. lactate, FBC, U&Es, cross-match, cultures; ABG; ECG and troponin (cardiogenic); echo (tamponade/RV strain/function); imaging for the source; cross-ref acute_care for the full sepsis/anaphylaxis algorithms.

Management

ABCDE; identify the type and treat the cause (fluids/blood, vasopressors, or relieve the obstruction)

1ABCDE with oxygen and IV access; take lactate and identify the type of shock from the JVP, peripheries and history.Gate: Cardiogenic or obstructive shock (raised JVP, pulmonary oedema) → aggressive fluids worsen it; treat the pump/obstruction (PCI, pericardiocentesis, chest decompression, thrombolysis). Anaphylaxis → IM adrenaline first.
2Hypovolaemic → fluids/blood + control the source; septic → Sepsis Six and noradrenaline for refractory hypotension; reassess perfusion and lactate. Escalate to critical care.

ABCDE + oxygen + IV access; treat by type — the unifying first step

Hypovolaemic/septic: fluid resuscitation (blood for haemorrhage); vasopressors (noradrenaline) for refractory distributive shock — sepsis → Sepsis Six; haemorrhage → control bleeding + transfuse

Cardiogenic: inotropes/vasopressors, treat the cause (PCI for MI), cautious fluids — avoid fluid overload

Obstructive/anaphylactic: treat the cause — IM adrenaline (anaphylaxis), chest decompression, pericardiocentesis, thrombolysis (massive PE) — the specific reversal

Key points

Shock = inadequate perfusion; the type decides treatment. Empty + cool → hypovolaemic (fluids/blood). Raised JVP/pulmonary oedema → cardiogenic or obstructive (fluids HARM — treat the cause). Warm + vasodilated → distributive (sepsis/anaphylaxis). Anaphylaxis = IM adrenaline now. Full algorithms cross-ref acute_care.

Monitor & prognosis

Perfusion, lactate clearance, urine output, haemodynamics; critical-care involvement.

Depends on type and reversibility; early recognition and cause-directed treatment are decisive.

Source: Resuscitation Council UK; cross-ref acute_care (sepsis/anaphylaxis)