Differential Diagnosis of Delirium – DELIRIUMS mnemonic

Common etiologies of delirium: Remember: delirium usually has more than one cause

D	Drug effect or withdrawal: benzos, narcotics, EtOH, SSRI, anticholinergics, Digoxin, antihistamines, muscle/bladder relaxants; especially in the elderly, even in low doses. Drugs also cover toxins and heavy metals.
E	Environmental factors (malfunction or lack of assistive devices or steps: hearing aids, eyeglasses, contact lenses, sleep/wake cycle, immobilization). Things that can help: Reorient, sleep protocols, music, noise control, ambulation. Emotional (e.g. anxiety, pain)
L	Low oxygen (e.g. MI, PE, anemia) or high PCO2 (e.g. COPD) states. Consider checking respiratory status (ABGs-PaO2 and PCO2)
I	Infection: pneumonia, UTI, skin ulcers, sepsis, shock.
R	Retention of urine or stool – i.e. urinary retention or constipation
I	Intracranial abnormality [Electrical problem – Seizure (ictal state); Plumbing problem (Stroke & TIA: pipe leaks as with a hemorrhage e.g. ICH or is blocked as with an embolus). Wall problem (space occupying lesion or tumor/mass). Also a head trauma or space occupying lesion or mass. These are the neurological causes.
U	Underhydration/undernutrition: Dehydration/poor oral intake/NPO
M	Metabolic (electrolytes, glucose, thyroid, endocrine disorder, liver, kidney). Post-operative state, deficiency. Get labs like Na+, K+, Ca+, BUN/Cr, NH3+ etc.
S	Sleep disturbances