AKT · Acute care/Resuscitation & shock

Shock — types & approach

Inadequate tissue perfusion — 4 mechanistic categories

Overview

A state of inadequate end-organ perfusion. The exam tests assigning the mechanism — hypovolaemic, cardiogenic, distributive (sepsis/anaphylaxis/neurogenic) or obstructive — because the mechanism dictates the treatment.

Recognise

All: hypotension, tachycardia, poor perfusion (cool/mottled or warm/flushed), oliguria, altered mentation
Hypovolaemic: bleeding/fluid loss, cold peripheries, low JVP
Cardiogenic: pump failure, raised JVP, pulmonary oedema
Distributive: warm peripheries, vasodilation (sepsis/anaphylaxis/neurogenic)
Obstructive: tension pneumothorax, cardiac tamponade, massive PE

Red flags

Obstructive causes (tension pneumothorax, tamponade, massive PE) need immediate mechanical relief, not just fluids

Differentials & how to tell them apart

Hypovolaemic shockfluid/blood loss → fluids/blood; low JVP, cold

Cardiogenic shockpump failure → inotropes, NOT large fluid boluses; raised JVP, oedema

Distributive (septic/anaphylactic/neurogenic)vasodilation, warm; treat cause + vasopressors

Obstructive shocktamponade/tension pneumothorax/PE → relieve the obstruction

Investigations

ABCDE, lactate, ABG; bedside echo/USS, ECG, CXR; identify the category to direct treatment.

Management

Treat by mechanism: fluids/blood (hypovolaemic), inotropes (cardiogenic), vasopressors + cause (distributive), relieve obstruction (obstructive)

1ABCDE + identify the category. Hypovolaemic/distributive: IV fluids (± blood) first. Cardiogenic: cautious fluids, inotropes. Obstructive: immediate mechanical relief.Gate: In CARDIOGENIC shock large fluid boluses worsen pulmonary oedema → inotropes/critical care, not aggressive fluids
2Treat the underlying cause; escalate to critical care; vasopressors for refractory hypotension.

Fluids ± blood — first for hypovolaemic/distributive; cautious in cardiogenic

Vasopressors / inotropes — noradrenaline (distributive), inotropes (cardiogenic) — critical care

Key points

The trap is giving fluids to cardiogenic or obstructive shock. JVP and lungs distinguish them: low JVP + clear lungs = hypovolaemic; raised JVP + wet lungs = cardiogenic; raised JVP + clear lungs = obstructive.

Monitor & prognosis

MAP, lactate, urine output, response to the chosen intervention.

Depends on cause and speed of correction.

Source: Resuscitation Council UK; ICU texts