What is the proper preoperative workup for a patient with orthostatic hypotension, fatigue, weakness, and dyspnea?

Preoperative Workup for Patients with Orthostatic Hypotension, Fatigue, Weakness, and Dyspnea

The proper preoperative workup for a patient with orthostatic hypotension, fatigue, weakness, and dyspnea must include a standardized orthostatic hypotension test, comprehensive cardiovascular evaluation, assessment for underlying causes, and optimization of volume status prior to surgery. 1

Confirming Orthostatic Hypotension

• Perform a standardized orthostatic hypotension test:
  • Measure blood pressure after 10 minutes of lying down
  • Measure again at 1,2, and 3 minutes after standing
  • Confirm diagnosis if there is a decrease in systolic BP ≥20 mmHg (or ≥30 mmHg in hypertensive patients) and/or diastolic BP ≥10 mmHg 1, 2

Cardiovascular Evaluation

• Obtain a 12-lead ECG to assess for:
  • Arrhythmias
  • Ischemic changes
  • QTc prolongation (particularly important in diabetic patients with possible cardiac autonomic neuropathy) 1, 3
• Consider echocardiography if:
  • History of heart failure or cardiac symptoms
  • Abnormal cardiac exam findings
  • Dyspnea is a prominent symptom 3
• Evaluate for silent myocardial ischemia in high-risk patients (e.g., diabetics with autonomic neuropathy) 3

Assessment for Underlying Causes

• Evaluate for common causes of orthostatic hypotension:
  • Medication-induced (diuretics, vasodilators, antihypertensives) 3
  • Volume depletion
  • Neurogenic causes:
    • Diabetic autonomic neuropathy
    • Parkinson's disease
    • Multiple system atrophy
  • Adrenal insufficiency 1
• Laboratory tests:
  • Complete blood count (to assess for anemia)
  • Comprehensive metabolic panel (electrolytes, renal function)
  • Hemoglobin A1c (if diabetic)
  • Consider BNP/pro-BNP if heart failure is suspected 3

Cardiac Autonomic Neuropathy Assessment

• For diabetic patients, consider specific testing for cardiac autonomic neuropathy (CAN):
  • Analysis of heart rate variations during standardized tests:
    • Deep respiration
    • Active orthostatism
    • Valsalva maneuver 3
  • Ambulatory blood pressure measurement to detect non-dipping pattern
  • QTc interval measurement (prolongation >440 ms suggests CAN) 3

Volume Status Optimization

• Consider administering 1-2 liters of saline 24 hours prior to surgery 1
• Implement a high-sodium diet preoperatively when appropriate 1
• Assess for signs of hypovolemia or hypervolemia

Medication Management

• Review current medications and consider:
  • Discontinuing or reducing diuretics if possible
  • Adjusting vasodilators that may worsen orthostatic hypotension
  • Temporarily discontinuing medications that exacerbate orthostatic hypotension 3, 1
• For severe orthostatic hypotension, consider preoperative treatment with:
  • Midodrine (5-20mg three times daily) - an alpha-1 agonist that increases vascular tone 1, 4
  • Fludrocortisone (0.1-0.3mg daily) - expands plasma volume 1

Anesthetic Planning

• Plan for intraoperative hemodynamic monitoring
• Prepare for potential vasopressor support during anesthesia induction and maintenance
• Consider use of compression stockings during surgery 1

Common Pitfalls to Avoid

• Don't assume all hypotension is due to hypovolemia
• Don't focus solely on BP numbers rather than symptoms and end-organ perfusion
• Don't overlook non-pharmacological measures for orthostatic hypotension
• Don't treat hypertension too aggressively, which can worsen orthostatic hypotension 1
• Don't miss cardiac autonomic neuropathy in diabetic patients, which increases perioperative risk 3

This comprehensive preoperative workup will help identify the underlying cause of orthostatic hypotension, optimize the patient's condition before surgery, and guide appropriate perioperative management to reduce morbidity and mortality.