Treatment of Low Blood Pressure (Hypotension)
Initial Approach: Distinguish Orthostatic from Non-Orthostatic Hypotension
For symptomatic low blood pressure, begin by measuring blood pressure after 5 minutes of lying/sitting, then at 1 and 3 minutes after standing to diagnose orthostatic hypotension (defined as ≥20 mmHg systolic or ≥10 mmHg diastolic drop). 1
Identify and Address Reversible Causes First
- Immediately discontinue or switch medications that worsen hypotension rather than simply reducing doses—this includes diuretics, vasodilators, ACE inhibitors, calcium channel blockers, alpha-blockers, and psychotropic medications 1, 2
- Drug-induced autonomic failure is the most frequent cause of orthostatic hypotension 1
- Evaluate for volume depletion, anemia, endocrine disorders (adrenal insufficiency, hypothyroidism), and alcohol use 1
Non-Pharmacological Management (First-Line for All Patients)
These interventions should be implemented before or alongside pharmacological therapy:
Fluid and Salt Management
- Increase fluid intake to 2-3 liters daily (unless contraindicated by heart failure) 1, 2
- Increase salt intake to 6-9 grams daily (if not contraindicated) 3, 1, 2
- Acute water ingestion of ≥480 mL provides temporary relief with peak effect at 30 minutes 1
Physical Countermeasures
- Teach leg crossing, squatting, stooping, and muscle tensing during symptomatic episodes—particularly effective in patients under 60 years with prodromal symptoms 1, 2
- Use compression garments (waist-high stockings and abdominal binders) to reduce venous pooling 1, 2
Lifestyle Modifications
- Elevate the head of bed by 10 degrees during sleep to prevent nocturnal polyuria and supine hypertension 1, 2
- Eat smaller, more frequent meals to reduce post-prandial hypotension 3, 1, 2
- Encourage physical activity and exercise to avoid deconditioning, which worsens orthostatic intolerance 3, 1
- Implement gradual staged movements with postural changes 1
Pharmacological Management (When Non-Pharmacological Measures Fail)
The therapeutic goal is minimizing postural symptoms rather than restoring normotension. 3, 1 Treatment should be continued only for patients who report significant symptomatic improvement. 4
First-Line Pharmacological Options
Midodrine is the preferred first-line agent:
- Start with 2.5-5 mg three times daily, titrating up to 10 mg three times daily as needed 1, 2, 4
- Acts as a peripheral selective α1-adrenergic agonist causing arteriolar and venous constriction 3, 1
- Take the last dose at least 3-4 hours before bedtime (avoid doses after 6 PM) to prevent supine hypertension during sleep 1, 2
- FDA-approved for symptomatic orthostatic hypotension 4
- Can increase standing systolic BP by 15-30 mmHg for 2-3 hours 1
Critical midodrine precautions:
- Monitor carefully for supine hypertension (BP >200 mmHg systolic possible) 4
- Avoid in patients with severe cardiac disease, acute renal failure, urinary retention, pheochromocytoma, or thyrotoxicosis 4
- Use cautiously with cardiac glycosides, beta-blockers, or other agents that reduce heart rate 4
- Avoid concomitant use with MAO inhibitors, other vasoconstrictors (phenylephrine, pseudoephedrine, ephedrine), or linezolid 4
Alternative First-Line Options
Fludrocortisone:
- Start with 0.05-0.1 mg daily, titrate individually to 0.1-0.3 mg daily (maximum 1.0 mg daily) 3, 1, 2
- Acts through sodium retention and vessel wall effects, expanding plasma volume 3, 1
- Monitor for supine hypertension, hypokalemia, congestive heart failure, and peripheral edema 3, 1
- Contraindicated in active heart failure, severe cardiac dysfunction, pre-existing supine hypertension, and severe renal disease 1
- Check electrolytes periodically due to mineralocorticoid effects causing potassium wasting 1
Droxidopa:
- FDA-approved for neurogenic orthostatic hypotension 3, 1
- Particularly effective for Parkinson's disease, pure autonomic failure, and multiple system atrophy 1
- May reduce falls 1
Second-Line and Combination Therapy
For Non-Responders to Monotherapy
- Consider combination therapy with midodrine and fludrocortisone 1
- Pyridostigmine may be beneficial for refractory neurogenic orthostatic hypotension, particularly in elderly patients, with fewer side effects than alternatives 1
For Patients with Supine Hypertension
- Use shorter-acting antihypertensives at bedtime that affect baroreceptor activity: guanfacine, clonidine, shorter-acting calcium blockers (isradipine), or shorter-acting β-blockers (atenolol, metoprolol tartrate) 3, 2
- Enalapril is an alternative if patients cannot tolerate preferred agents 3
Special Populations
Diabetic patients with autonomic neuropathy:
- Consider underlying cardiovascular autonomic neuropathy as the cause 2
- Optimize glucose control to prevent progression of autonomic dysfunction 2
- Near-normal glycemic control implemented early can delay or prevent development of autonomic neuropathy 3
Elderly patients (≥85 years) with coexisting hypertension:
- Prefer long-acting dihydropyridine calcium channel blockers or RAS inhibitors as first-line antihypertensive therapy 1
- Start with lower doses and titrate more gradually 2
- Monitor closely for supine hypertension 2
Heart failure patients:
- Prioritize SGLT2 inhibitors and mineralocorticoid receptor antagonists as they have minimal impact on blood pressure 2
- Space out medications to reduce synergistic hypotensive effects 2
Monitoring and Safety Considerations
- Measure blood pressure supine and standing at each visit to balance symptom relief against supine hypertension risk 1
- Reassess within 1-2 weeks after medication changes 1
- Patients should report symptoms of supine hypertension immediately (cardiac awareness, pounding in ears, headache, blurred vision) and discontinue medication if it persists 4
- Avoid supine/nocturnal hypertension, as this can cause end-organ damage 1
- The risk of falls and injury from postural hypotension must be balanced against cardiovascular protection 1
Postoperative Hypotension (Acute Setting)
For acute postoperative hypotension, perform a passive leg raise (PLR) test to determine if inadequate preload is contributing—if PLR corrects hypotension, intravenous fluid is appropriate; if not, focus on vascular tone and chronotropy/inotropy with vasopressor or inotropic support 3