Delirium with infection/sepsis
Delirium as a sign of infection or sepsis — what to check and when it is urgent.
Key points
- Infection is a leading precipitant of delirium; in older adults it may present primarily as confusion.
- Think early about sepsis and hypoxaemia and actively search for the infectious source.
- Delirium is commonly multifactorial: inflammation, dehydration, metabolic changes and medication effects often coexist.
Clinical context
Pneumonia, urinary tract infection, influenza and sepsis frequently trigger delirium in patients with reduced cognitive reserve. Fever may be absent in older adults, and typical localising symptoms can be subtle. A sudden change in attention, behaviour or sleep should prompt evaluation for infection.
Mechanisms
Systemic inflammation drives neuroinflammatory signalling and neurotransmitter imbalance, while hypoxaemia, hypotension and metabolic derangements reduce cerebral perfusion and resilience. Hospital factors—sleep loss, immobility, sensory deprivation—can intensify symptoms.
Common sources
- Respiratory: pneumonia, COPD exacerbation.
- Urinary: UTI, infected urinary retention.
- Skin/soft tissue: cellulitis, infected wounds, pressure ulcers.
- Abdominal: cholecystitis, diverticulitis, intra‑abdominal infection.
- Device‑related infections (catheters/lines) in hospitalised patients.
Assessment
Assess vital signs (temperature, heart rate, blood pressure, respiratory rate, SpOâ‚‚) and screen for sepsis features (tachypnoea, hypotension, rigors, oliguria, profound weakness). Typical tests include CBC, CRP, electrolytes, renal function and glucose; urinalysis; chest imaging as indicated; and cultures when severe infection is suspected (preferably before antibiotics).
Management
Management is source‑directed: antimicrobial therapy when indicated, oxygen support for hypoxaemia, fluids for dehydration, correction of metabolic abnormalities and pain control. Concurrent delirium care includes orientation, sleep protection, mobilisation, sensory aids and minimising deliriogenic drugs.
Practical tables
| Suspicion | Clues | Next step |
|---|---|---|
| Pneumonia | cough, dyspnoea, low SpOâ‚‚ | exam + chest imaging |
| UTI | urinary symptoms may be absent; urine change | urinalysis; culture if indicated |
| Sepsis | rigors, tachypnoea, hypotension, oliguria | urgent assessment |
Related topics
When it is urgent • Causes • Dehydration & electrolytes • Medication‑induced delirium