Multi-organ dysfunction syndrome

Overview

Multi-organ dysfunction syndrome (MODS) - a clinical syndrome in which two or more organ systems fail progressively; not a disease itself but the final common pathway of severe illness (sepsis, trauma, pancreatitis, burns).

Pathophysiology

•Severe insult → SIRS → massive cytokine release (TNF-alpha, IL-1, IL-6) → endothelial injury → microvascular permeability → tissue oedema → cellular hypoxia → organ failure

•Coagulation activation runs in parallel → DIC → further compromise of perfusion

•Primary MODS - direct organ injury (e.g. ARDS from aspiration, AKI from rhabdomyolysis)

•Secondary MODS - remote organ failure from systemic inflammatory response (classic sepsis pattern)

Presentation

•Respiratory - hypoxia, tachypnoea, bilateral crackles (ARDS pattern)

•Cardiovascular - hypotension, tachycardia, cold peripheries, elevated lactate

•Renal - oliguria/anuria, rising creatinine and urea, fluid overload

•Hepatic - jaundice, coagulopathy, right upper quadrant tenderness, hepatic encephalopathy

•Haematological - petechiae, purpura, bleeding from IV sites (DIC)

•Neurological - confusion, delirium, reduced GCS

•Metabolic - metabolic acidosis (raised lactate, low pH, low bicarbonate), hypo/hyperglycaemia

Investigations

•ABG - PaO2/FiO2 ratio, metabolic acidosis, lactate (serial measurements guide resuscitation)

•FBC - thrombocytopaenia, anaemia, leukocytosis/leucopaenia

•U&E/creatinine - renal dysfunction; guides fluid and renal replacement therapy

•LFTs + coagulation screen (PT, APTT, fibrinogen, D-dimer) - hepatic failure, DIC

•Blood cultures x2 - before starting antibiotics

•CXR - bilateral infiltrates (ARDS), pneumonia, pulmonary oedema

•Echocardiography - septic cardiomyopathy

•CRP/procalcitonin - support sepsis diagnosis, guide antibiotic de-escalation

🏆 Gold standard

•SOFA score (calculated serially) - quantifies organ dysfunction severity and guides prognosis

Management

•First-line - treat the precipitant: broad-spectrum IV antibiotics within 1 hour of sepsis recognition (Sepsis 6); source control (drain abscess, remove infected line, surgery)

•First-line - haemodynamic resuscitation: IV crystalloid boluses targeting MAP >65 mmHg and lactate clearance; noradrenaline first-line vasopressor for fluid-refractory hypotension

•First-line - respiratory support: supplemental O2 → NIV → invasive mechanical ventilation if PaO2/FiO2 <26.7 kPa; lung-protective ventilation (tidal volume 6 mL/kg)

•First-line - renal support: cautious fluid balance; CVVH for severe AKI with refractory hyperkalaemia, acidosis, or fluid overload

•First-line - glycaemic control: target blood glucose 6-10 mmol/L with insulin infusion; avoid hypoglycaemia

•First-line - nutrition: early enteral nutrition within 24-48 hours of ICU admission (preferred over parenteral to preserve gut integrity)

•Second-line - haematological: FFP, cryoprecipitate, platelets for bleeding/DIC; packed red cells if Hb <70 g/L (or <90 g/L in cardiac disease)

•Second-line - corticosteroids: hydrocortisone 200 mg/day IV in refractory septic shock as adjunct to vasopressors

•Third-line - ECMO: refractory respiratory failure (severe ARDS) at specialist centres

⚠️

Goals-of-care decisions must be made proactively - when MODS progresses despite maximal support, involve patient (if competent), family, intensivist, and palliative care team early; do not leave until the final hours.

Prognosis by organ failure number

•2 organs failing - mortality ~40-50%

•4+ organs failing - mortality >80%

•SOFA score - assigns 0-4 points across 6 systems (respiratory, coagulation, hepatic, cardiovascular, neurological, renal); score ≥2 above baseline = organ dysfunction (Sepsis-3); serial measurement guides prognosis

Complications and follow-up

•Post-intensive care syndrome (PICS) - cognitive impairment, ICU-acquired weakness, PTSD in up to 50% of survivors

•Chronic kidney disease - AKI in MODS significantly increases long-term CKD risk

•VAP and nosocomial infections - CLABSI, *C. difficile* during prolonged ICU stay

•Structured ICU follow-up clinic at 2-3 months post-discharge; physiotherapy, psychology, organ-specific monitoring (renal, hepatic, pulmonary, cognitive)