Key Facts

Intensive care medicine is a multidisciplinary specialty providing advanced organ support and monitoring for the most critically ill patients. Early recognition of deterioration, protocolised care, and multidisciplinary teamwork are fundamental to good outcomes.

Epidemiology

Approximately 250,000 patients are admitted to ICU annually in the UK. ICU bed provision is approximately 6.6 per 100,000 population (lower than many comparable countries). Overall ICU mortality is approximately 20%, varying from <5% for elective post-surgical to >50% for multi-organ failure.

Aetiology

Common reasons for ICU admission:

• Sepsis/septic shock (most common medical)
• Acute respiratory failure/ARDS
• Post-operative monitoring (complex surgery, complications)
• Cardiovascular failure (MI, cardiogenic shock, arrhythmia)
• Neurological (stroke, status epilepticus, traumatic brain injury)
• Trauma (polytrauma, burns)
• Post-cardiac arrest

Pathophysiology

Critical illness is characterised by the failure or threatened failure of one or more organ systems. The systemic inflammatory response syndrome (SIRS) and its progression to multi-organ dysfunction syndrome (MODS) represents a common final pathway in many critically ill patients, driven by dysregulated inflammation, endothelial dysfunction, microcirculatory failure, and mitochondrial dysfunction.

Levels of Care

• Level 0: Ward care — can be met through normal ward care
• Level 1: Acute ward care with additional advice from critical care (step-down)
• Level 2 (HDU): Single-organ support (excluding advanced respiratory)
• Level 3 (ICU): Advanced respiratory support or ≥2 organ support

Assessment of the Critically Ill Patient

• ABCDE approach: Systematic assessment
• Monitoring: Continuous ECG, SpO2, invasive arterial BP, CVP, urine output, temperature
• Organ support: Ventilation, vasopressors/inotropes, renal replacement therapy, blood products

Common ICU Interventions

• Endotracheal intubation and mechanical ventilation
• Central venous catheter (internal jugular, subclavian, femoral)
• Arterial line (radial most common)
• Vasopressor/inotrope infusions
• Renal replacement therapy (CVVHDF most common in ICU)
• Enteral/parenteral nutrition
• Sedation and analgesia

Red Flags

• Rising NEWS2 score on the ward — early warning of deterioration
• Lactate >4 mmol/L — tissue hypoperfusion, high mortality
• Acute deterioration in ventilator parameters — consider pneumothorax, blocked ETT, PE
• New onset organ failure — reassess for sepsis, haemorrhage, or drug reaction

Bedside

• ABG: pH, PaO2, PaCO2, lactate, Hb, glucose, electrolytes
• Echocardiography (point-of-care): Assess cardiac function, fluid status, tamponade
• Lung USS: Pleural effusion, pneumothorax, consolidation
• Urine output: Hourly monitoring — target >0.5 mL/kg/hr

Bloods

• FBC, U&Es, LFTs, CRP, lactate: Baseline and serial monitoring
• Coagulation, fibrinogen: DIC screening
• Blood cultures: Before antibiotics in sepsis
• Procalcitonin: Guide antibiotic duration
• Troponin: If cardiac ischaemia suspected

Imaging

• CXR (daily or as indicated): ETT position, line position, lung pathology
• CT: Guided by clinical question (CT head, CTPA, CT abdomen)

Special Tests

• Cardiac output monitoring: PiCCO, LiDCO, PA catheter, echocardiography
• EEG: Status epilepticus, prognostication post-cardiac arrest
• Bronchoscopy: Persistent collapse, suspected VAP, bronchoalveolar lavage

Non-pharmacological

• Early mobilisation: Reduces ICU-acquired weakness, delirium, and duration of ventilation
• Nutrition: Enteral feeding within 48 hours of admission (nasogastric)
• DVT prophylaxis: LMWH + mechanical (IPC/TEDS)
• Stress ulcer prophylaxis: PPI or ranitidine (for mechanically ventilated patients)
• Glycaemic control: Target glucose 6-10 mmol/L (NICE-SUGAR trial)
• ABCDEF bundle: Assess/manage pain, Both SATs and SBTs, Choice of sedation, Delirium management, Early mobilisation, Family engagement

Pharmacological

• Sepsis: IV antibiotics within 1 hour of recognition; noradrenaline 0.05-1mcg/kg/min to target MAP ≥65mmHg; hydrocortisone 200mg/day if vasopressor-refractory (ADRENAL trial)
• Sedation: Propofol 0.3-4mg/kg/hr or midazolam 0.03-0.2mg/kg/hr; target RASS 0 to -2
• Analgesia: Morphine 1-5mg/hr IV or fentanyl 25-200mcg/hr
• Delirium: Non-pharmacological first; haloperidol 0.5-2mg IV if agitated delirium; dexmedetomidine 0.2-1.4mcg/kg/hr
• Vasopressors: Noradrenaline (first-line), vasopressin 0.03 units/min (adjunct), dobutamine 2.5-20mcg/kg/min (inotrope)

Surgical/Interventional

• Renal replacement therapy: CVVHDF for AKI with refractory hyperkalaemia, acidosis, fluid overload, or uraemia
• Percutaneous tracheostomy: Consider at day 7-10 of mechanical ventilation
• Source control: Drainage of abscesses, debridement of infected tissue

Referral Criteria

• Any patient with acute organ failure or threatened failure — ICU outreach/referral
• NEWS2 ≥7 or single parameter score of 3 — urgent senior review and ICU referral
• Post-cardiac arrest — ICU for targeted temperature management and neuroprognostication

• Overall ICU mortality (UK): ~20%; hospital mortality ~25%
• Septic shock: Mortality 30-40% despite best care
• ARDS: Mortality 35-45% depending on severity (Berlin classification)
• Post-ICU outcomes: 25-50% of ICU survivors have significant physical, psychological, or cognitive impairment at 1 year (post-intensive care syndrome — PICS)
• ICU-acquired weakness: Affects 25-50% of patients ventilated >7 days

Sequential Organ Failure Assessment (SOFA) Score

Key ICU Trials