Silent hypoactive delirium

Specialty: Geriatrics.

• acute hypoactive confusion syndrome
• silent delirium of the old man
• acute fluctuating lethargy
• apathetic confusional state

Why it occurs

• Acute occult urinary tract infection, atypical pneumonia or larval bacteremia without fever or localizing signs
• Severe hydroelectrolyte alteration, mainly acute hyponatremia induced by thiazides or syndrome of inappropriate ADH secretion (SIADH)
• Massive fecal impaction or acute bladder balloon that generates a maladaptive neurovegetative response
• Acute silent cerebral ischemia located in prefrontal, thalamic or cingulate gyrus regions
• Serious side effects due to the recent introduction of drugs with a high anticholinergic load or benzodiazepines with a long half-life

Initial workup

Systematic application of the Confusion Assessment Method (CAM) or the 4AT rapid screening test; urgent blood analysis (complete blood count with formula, blood glucose, sodium, potassium, ionic calcium, creatinine, urea, C-reactive protein and venous blood gases); urine test strip and subsequent culture; portable or standard chest x-ray; 12-lead electrocardiogram; Urgent computed tomography (CT) of the head if there is suspicion of exacerbated chronic subdural hematoma or previous trauma.

Standard management

• Systematically avoid the use of sedative neuroleptics unless there are distressing hallucinations or agitation that compromise safety; If essential, use Haloperidol at ultra-low doses — 0.25 mg to 0.5 mg orally or subcutaneously, maximum twice a day, withdrawing the drug when delirium subsides
• Sodium chloride 0.9% — intravenous fluid therapy at a controlled rate of 40-60 ml/h if dehydration or hypovolemic hyponatremia is confirmed, monitoring lung auscultation
• Immediate suspension of benzodiazepines, first-generation antihistamines and strong opioid analgesics.