General MedicineTier 1Disease (DEADMAN)

Hypotension or shock - septic

Description

Septic shock = sepsis + vasopressor requirement to maintain MAP >=65 mmHg AND lactate >2 mmol/L despite adequate fluid resuscitation
A subset of sepsis, distinguished by persistent hypotension/hypoperfusion despite fluids

Epidemiology

Highest sepsis-associated mortality subgroup
Risk factors: extremes of age, immunosuppression, indwelling devices, chronic disease (diabetes, cirrhosis, CKD, malignancy)

Aetiopathogenesis

Infection -> systemic inflammatory cascade -> vasodilation (distributive shock) + endothelial dysfunction + capillary leak + relative/absolute hypovolaemia
Myocardial depression can co-exist (septic cardiomyopathy) - mixed distributive + cardiogenic picture in some
Microvascular dysfunction impairs oxygen extraction independent of macrocirculatory flow -> persistent lactate elevation despite normalised BP

Diagnosis

Clinical + biochemical: source of infection + SOFA score increase + refractory hypotension + raised lactate
Warm shock (early, vasodilated, bounding pulses) may progress to cold shock (myocardial depression, poor perfusion)

Management

1. Resuscitation - individualised, not fixed-volume

IV crystalloid, guided by dynamic markers (passive leg raise, lactate clearance) rather than a fixed target volume
Avoid over-resuscitation - associated with worse outcomes (pulmonary oedema, abdominal compartment syndrome)

2. Source control and antimicrobials

Broad-spectrum antibiotics within 1 hour, de-escalate on cultures
Identify and control the source (drain, debride, remove infected device) as early as possible

3. Vasopressor support

Noradrenaline first-line, target MAP >=65 mmHg
Add vasopressin as a second agent to reduce noradrenaline dose rather than escalating noradrenaline alone
Consider hydrocortisone in refractory shock (vasopressor-dependent despite adequate fluids)

4. Monitoring and organ support

Arterial line, central access, serial lactate
Renal replacement therapy, mechanical ventilation as needed for organ support

Associations

Multi-organ dysfunction (AKI, ARDS, DIC, hepatic dysfunction)
Critical illness myopathy/neuropathy in survivors
Post-sepsis syndrome - long-term cognitive and functional impairment

Natural history & complications

Mortality remains substantial (~30-40%) despite bundled care, worse with delayed recognition/treatment
Early antibiotics and source control are the strongest modifiable determinants of survival
Survivors face prolonged recovery, higher risk of recurrent hospitalisation and long-term functional decline

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