What are the causes of hypotension (Low Blood Pressure)?

From the Guidelines

Low blood pressure, or hypotension, requires immediate attention if symptoms like dizziness, fainting, blurred vision, or fatigue are present, and the most recent guidelines suggest that classical orthostatic hypotension is associated with increased mortality and cardiovascular disease prevalence, thus necessitating prompt treatment. For mild cases without symptoms, no treatment is typically necessary. However, if symptoms are present, several interventions can help. Increase your fluid intake to 2-3 liters daily, especially water, to maintain blood volume, as suggested by 1. Consume more salt in your diet if you don't have conditions like heart failure or hypertension. Stand up slowly from sitting or lying positions to prevent orthostatic hypotension. Wear compression stockings to improve blood return from your legs to your heart. For medication-induced hypotension, your doctor might adjust dosages or switch medications.

Some key points to consider in the management of low blood pressure include:

• Identifying and treating underlying causes like dehydration, blood loss, heart problems, or endocrine disorders
• Avoiding offending agents such as diuretics and vasodilators that can exacerbate orthostatic hypotension, as mentioned in 1
• Using non-pharmacological measures such as gradual staged movements with postural change, mild isotonic exercise, and increased fluid and salt intake, as recommended by 1
• Considering pharmacological treatment with medications like midodrine or fludrocortisone if symptoms persist, as suggested by 1 and 1

The most effective treatment approach should prioritize minimizing postural symptoms rather than restoring normotension, and should be individualized based on the patient's specific condition and response to treatment, as emphasized by 1. In severe cases, medications like fludrocortisone (0.1-0.2 mg daily) or midodrine (2.5-10 mg three times daily) may be prescribed, as mentioned in 1. These work by increasing blood volume or constricting blood vessels to raise blood pressure. Low blood pressure can reduce blood flow to vital organs, so persistent or severe symptoms warrant medical attention to prevent complications, as highlighted by 1.

From the FDA Drug Label

Midodrine forms an active metabolite, desglymidodrine, that is an alpha1-agonist, and exerts its actions via activation of the alpha-adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure. Administration of midodrine results in a rise in standing, sitting, and supine systolic and diastolic blood pressure in patients with orthostatic hypotension of various etiologies Standing systolic blood pressure is elevated by approximately 15 to 30 mmHg at 1 hour after a 10 mg dose of midodrine, with some effect persisting for 2 to 3 hours.

Low Blood Pressure (Hypotension) Treatment: Midodrine is used to treat orthostatic hypotension, which is a condition where blood pressure drops when standing up, causing dizziness or lightheadedness.

• Key Benefits: Midodrine increases blood pressure by activating alpha-adrenergic receptors, which helps to improve symptoms of orthostatic hypotension.
• Dosage and Administration: The typical dose of midodrine is 10 mg three times a day, with the last dose taken no later than 6 P.M. to minimize nighttime supine hypertension.
• Important Considerations: Patients should be monitored for supine hypertension and advised to take their last daily dose of midodrine 3 to 4 hours before bedtime 2.
• Concomitant Medications: Midodrine should be used with caution in patients taking other medications that can increase blood pressure, such as phenylephrine, ephedrine, or dihydroergotamine 2.

From the Research

Low Blood Pressure (BP) Overview

• Low BP, also known as hypotension, can be caused by various factors, including orthostatic hypotension, which is an excessive fall in blood pressure while standing 3.
• Orthostatic hypotension can result from a decrease in cardiac output or defective or inadequate vasoconstrictor mechanisms 3.

Treatment Options for Orthostatic Hypotension

• Fludrocortisone, a mineralocorticoid, is considered a first- or second-line pharmacological therapy for orthostatic hypotension, alongside mechanical and positional measures such as increasing fluid and salt intake and venous compression methods 3.
• Midodrine, an alpha-adrenergic agonist, is also used to treat orthostatic hypotension and has been shown to be effective in patients with significant preservation of autonomic reflexes 4.
• Comparative studies have shown midodrine to have similar efficacy to fludrocortisone and other medications in patients with orthostatic hypotension 5.

Comparison of Fludrocortisone and Midodrine

• A retrospective cohort study found that fludrocortisone users had higher rates of all-cause hospitalizations compared to midodrine users, especially among patients with congestive heart failure 6.
• Midodrine has been shown to be well-tolerated, with the most commonly reported adverse events being piloerection, pruritus, paraesthesias, urinary retention, and chills 5.

Accurate Assessment of Patient Status

• Traditional blood pressure measurement methods may not provide an accurate assessment of patient status, particularly in emergency medical settings 7.
• Newly emerging monitoring technologies, such as machine-learning algorithms, can improve patient diagnosis by analyzing arterial waveforms in real-time 7.