Autonomic Assessment for Orthostatic Intolerance

When Standing Makes the Patient Feel Worse, Measure the Response.

Orthostatic intolerance describes symptoms that occur or worsen when a person is upright and improve with sitting or lying down.

Physio PS is FDA 510(k) cleared and designed for use by physicians and healthcare providers.

Patients may describe:

  • Lightheadedness

  • Dizziness

  • Weakness

  • Palpitations

  • Fatigue

  • Presyncope

  • Exercise intolerance

  • Brain fog

  • Shortness of breath

  • A feeling of being unable to tolerate prolonged standing

Orthostatic intolerance is a clinical presentation, not a single diagnosis. The underlying cause may involve blood-volume abnormalities, medication effects, autonomic dysfunction, orthostatic hypotension, POTS, cardiovascular disease, deconditioning, or other conditions.

When Exercise Intolerance Raises Additional Questions

A cardiologist may encounter patients who report:

  • Reduced exercise capacity

  • Disproportionate fatigue with activity

  • Excessive heart-rate response

  • Poor heart-rate recovery

  • Lightheadedness during or after activity

  • Exercise-associated palpitations

  • Post-exertional worsening of symptoms

  • Exercise intolerance despite relatively reassuring conventional cardiac findings

These symptoms have many potential causes and require appropriate clinical evaluation.

Conventional Exercise Evaluation Still Matters

Depending on the patient, evaluation may include:

  • History and physical examination

  • ECG

  • Echocardiography

  • Exercise stress testing

  • Cardiopulmonary exercise testing

  • Rhythm monitoring

  • Laboratory evaluation

  • Pulmonary evaluation

  • Assessment of conditioning and other contributing factors

Autonomic assessment should complement—not replace—these established approaches when they are clinically indicated.

What Physio PS Adds

Physio PS is designed to provide quantitative information about autonomic regulation.

According to Physio PS, its approximately 15-minute non-invasive assessment evaluates parasympathetic and sympathetic activity independently and simultaneously using physiologic measurements including ECG, blood pressure, and heart rate.

This provides an additional autonomic perspective alongside conventional orthostatic measurements.

The Clinical Question Becomes:

What is happening to the patient's autonomic regulation when the cardiovascular system is responding to physiologic demand?

Orthostatic Intolerance and Cardiology

Consider autonomic assessment when a patient has:

  • Recurrent dizziness when standing

  • Presyncope

  • Unexplained palpitations

  • Orthostatic tachycardia

  • Blood-pressure changes with position

  • Symptoms that improve when recumbent

  • Persistent symptoms despite routine cardiac testing

  • Suspected POTS

  • Suspected autonomic dysfunction

Don't Confuse Orthostatic Symptoms With a Single Diagnosis

A patient who becomes dizzy after standing does not automatically have POTS.

Similarly, an abnormal heart-rate response does not by itself establish the cause of the patient's symptoms.

The clinical context matters.

Autonomic findings should be interpreted with the patient's symptoms, orthostatic vital signs, medical history, medication profile, ECG, rhythm evaluation, and other appropriate testing.

Add Information Without Replacing the Workup

Physio PS is designed to complement the broader cardiovascular assessment.

It can provide quantitative autonomic information that may help the clinician characterize the patient's physiology and establish a baseline for follow-up when clinically appropriate.

Measure the Response. Understand the Pattern. Then Determine the Next Step.

© Copyright 2026 Physio PS, Inc.-All rights reserved.