Master Specialist Critical Care Medicine (ICU5231)
for DHA Speciality

Core Concepts

Sepsis & Septic Shock: Life-threatening organ dysfunction caused by a dysregulated host response to infection (Sepsis-3 definition). Septic shock is sepsis with persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg and a serum lactate level >2 mmol/L despite adequate fluid resuscitation.
Acute Respiratory Distress Syndrome (ARDS): Acute onset, bilateral pulmonary infiltrates on chest imaging, severe hypoxemia (PaO2/FiO2 ratio ≤300 mmHg) not fully explained by cardiac failure or fluid overload (Berlin definition).
Shock: Syndrome of acute circulatory failure resulting in inadequate tissue perfusion and oxygen delivery. Types include hypovolemic, cardiogenic, obstructive, and distributive (e.g., septic, anaphylactic, neurogenic).
Acute Kidney Injury (AKI): Abrupt decrease in kidney function resulting in retention of nitrogenous wastes. Classified by KDIGO criteria based on serum creatinine increase or urine output decrease.
Increased Intracranial Pressure (ICP): Sustained elevation of ICP >20-22 mmHg, threatening cerebral perfusion pressure (CPP = MAP - ICP) and leading to brain herniation.

Clinical Presentation

• Systemic: Hypotension, tachycardia, altered mental status (AMS), fever or hypothermia, oliguria, generalized weakness, mottled skin.
• Respiratory: Tachypnea, dyspnea, use of accessory muscles, hypoxemia, cyanosis, crackles/wheezes, decreased breath sounds.
• Cardiovascular: Arrhythmias, peripheral edema, signs of fluid overload (JVP, pulmonary edema) or dehydration (poor skin turgor, dry mucous membranes).
• Neurological: Decreased Glasgow Coma Scale (GCS), focal neurological deficits, pupillary changes, posturing, seizures.
• Gastrointestinal: Nausea, vomiting, abdominal pain, ileus, absent bowel sounds.
• Renal: Oliguria (<0.5 ml/kg/hr), anuria, edema.

Diagnosis (Gold Standard)

Sepsis: Clinical suspicion with qSOFA score ≥2 (respiratory rate ≥22/min, altered mentation, systolic BP ≤100 mmHg) and/or SOFA score increase by ≥2 points, confirmed infection source, elevated lactate, positive blood cultures.
ARDS: Berlin criteria: Acute onset within 1 week of clinical insult, bilateral opacities on chest imaging (not fully explained by effusion, collapse, nodules), respiratory failure not fully explained by cardiac failure/fluid overload, PaO2/FiO2 ≤300 mmHg with PEEP ≥5 cmH2O (or CPAP).
Shock: Clinical presentation of hypoperfusion, persistently low MAP, elevated lactate. Specific diagnosis relies on detailed hemodynamic assessment (e.g., echocardiography for cardiogenic/obstructive, CVP/ScvO2 for distributive/hypovolemic).
Increased ICP: Direct invasive ICP monitoring (intraparenchymal catheter or external ventricular drain - EVD) showing sustained pressures >20-22 mmHg. CT head identifies structural causes (hemorrhage, edema, mass lesion).

Management (First Line)

• Resuscitation & Stabilization (ABCs):
  • Airway: Secure airway via intubation for respiratory failure, GCS <8, or airway protection.
  • Breathing: Mechanical ventilation, lung-protective strategy for ARDS (low tidal volume 4-6 ml/kg IBW, plateau pressure <30 cmH2O), optimal PEEP, maintain SpO2 90-96%.
  • Circulation: IV crystalloids (e.g., 30ml/kg for sepsis-induced hypotension), vasopressors (Norepinephrine first-line for septic shock), inotropes (Dobutamine for cardiogenic shock), target MAP >65 mmHg.
• Sepsis Management (Within 1 hour): Measure lactate, obtain blood cultures, administer broad-spectrum antibiotics, begin rapid 30 ml/kg crystalloid for hypotension/lactate >2, apply vasopressors if hypotensive after fluids.
• ARDS Management: Lung-protective ventilation, prone positioning for severe ARDS, neuromuscular blockers for persistent hypoxemia, judicious fluid management.
• AKI Management: Address underlying cause, optimize hemodynamics, avoid nephrotoxic agents, manage electrolytes, initiate Renal Replacement Therapy (RRT) for refractory fluid overload, severe hyperkalemia, metabolic acidosis, or uremia.
• Increased ICP Management: Elevate head-of-bed 30 degrees, maintain normothermia, sedation/analgesia (propofol, fentanyl), hyperosmolar therapy (Mannitol, hypertonic saline), maintain normocapnia (avoid hyperventilation), EVD drainage.

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