What is the initial workup for an elderly patient presenting with confusion and weakness?

Initial Workup for Confusion and Weakness in Elderly Patients

The initial workup for an elderly patient presenting with confusion and weakness should include assessment for delirium using validated screening tools, vital signs with particular attention to fever criteria, and evaluation of common reversible causes including infection, medication effects, and dehydration. 1

Step 1: Immediate Assessment

Vital Signs Assessment

• Temperature: Look for fever defined as:
  • Single oral temperature ≥100°F (37.8°C)
  • Repeated oral temperatures ≥99°F (37.2°C) or rectal temperatures ≥99.5°F (37.5°C)
  • Increase in temperature of ≥2°F (1.1°C) over baseline 1
• Blood pressure: Check for hypotension (systolic BP <90 mmHg) 2
• Heart rate: Assess for tachycardia or postural pulse changes 2
• Respiratory rate: Monitor for tachypnea or abnormal breathing patterns

Delirium Screening

• Use a two-step process:

  1. Highly sensitive delirium triage screen
  2. Brief Confusion Assessment Method (CAM) 1

• Assess for key features distinguishing delirium from dementia:

  Feature	Delirium	Dementia
  Onset	Acute	Insidious
  Course	Fluctuating	Constant
  Attention	Disordered	Generally Preserved*
  Consciousness	Disordered	Generally Preserved*
  Hallucinations	Often Present	Generally Preserved*

  *Variable in Advanced Dementia 1

Step 2: Focused Clinical Evaluation

Assess for Dehydration

• Check for at least four of these seven signs:
  • Confusion
  • Non-fluent speech
  • Extremity weakness
  • Dry mucous membranes
  • Dry tongue
  • Furrowed tongue
  • Sunken eyes 2

Neurological Assessment

• Perform Cincinnati Prehospital Stroke Scale:
  • Facial droop
  • Arm drift
  • Abnormal speech 1
• Assess proximal motor strength and evaluate for neuropathies 1

Functional Status Evaluation

• Document new or increasing:
  • Confusion
  • Incontinence
  • Falls
  • Deteriorating mobility
  • Reduced food intake
  • Failure to cooperate with staff 1

Step 3: Initial Laboratory and Diagnostic Testing

Basic Laboratory Tests

• Complete blood count: Check for elevated WBC (infection) or hematocrit (dehydration)
• Comprehensive metabolic panel:
  • Electrolytes (sodium, potassium, calcium)
  • BUN/creatinine ratio (>20:1 suggests dehydration)
  • Glucose (hypo/hyperglycemia)
  • Liver function tests
• Urinalysis and urine culture (UTI common in elderly) 1, 2
• Serum osmolality or calculated osmolarity (>295 mmol/L suggests dehydration) 2

Additional Testing Based on Clinical Suspicion

• Chest X-ray (pneumonia, CHF)
• ECG (myocardial infarction, arrhythmias)
• Arterial blood gas (hypoxia from pulmonary embolism or other causes) 3
• Blood cultures if fever present

Step 4: Medication Review

• Review all medications for potential side effects causing confusion or weakness
• Pay special attention to:
  • Anticholinergics
  • Sedative/hypnotics
  • Antipsychotics
  • Vasodilators
  • Diuretics
  • Pain medications 1

Common Pitfalls to Avoid

1. Assuming a single cause: Elderly patients often have multiple contributing factors to confusion and weakness 4
2. Missing dehydration: Often overlooked but common and treatable 2
3. Overlooking medication effects: Polypharmacy is common in elderly and can cause confusion 1
4. Attributing symptoms to dementia: Acute changes should not be attributed to underlying dementia without investigation 1
5. Inadequate fever detection: Using inappropriate temperature thresholds for elderly patients 1
6. Missing atypical presentations: Elderly patients may not present with classic symptoms of serious conditions 1

Special Considerations

• Infection in elderly often presents atypically with functional decline rather than classic symptoms 1
• Elderly patients have lower baseline temperatures, so lower thresholds should be used to define fever 1
• Delirium has high mortality if underlying causes are not addressed promptly 4
• Pulmonary embolism can present primarily as confusion in elderly due to hypoxia 3

By following this systematic approach, clinicians can efficiently identify and address the most common and serious causes of confusion and weakness in elderly patients.