Autonomic Testing

Autonomic reflex screen testing in San Diego

Autonomic reflex screen testing in San Diego

Autonomic testing, also known as autonomic reflex screen or autonomic response testing, is a non-invasive test that measures how the nervous system works to control blood pressure, heart rate and sweating. 

About autonomic testing at Scripps

Autonomic testing is used to help physicians diagnose the presence and severity of dysautonomia, a disorder of the autonomic nervous system (ANS). Your physician may recommend autonomic testing if you’re experiencing symptoms including: 


  • Abnormal sweating
  • Dizziness
  • Fainting
  • Fatigue
  • Fluctuating blood pressure
  • Numbness and burning in your hands or feet
  • Rapid heart rate
  • Shortness of breath


Your physician may order this test for other reasons as well.

What to expect during autonomic testing

Autonomic testing consists of activities designed to stimulate the autonomic nervous system to produce changes in blood pressure, heart rate, breathing and sweating in a controlled setting. We’ll review the procedure with you before starting. 


The test includes two main parts — a quantitative sudomotor axon reflex test and a cardiovascular autonomic test.

Quantitative sudomotor axon reflex test (QSART)

QSART is a test that measures the nerves that control sweating. During this first part of the autonomic test, we apply a mild electrical current to your skin to activate the nerves that supply the sweat glands. This allows us to assess whether the sympathetic nerve terminals in your skin are able to release a neurotransmitter (called acetylcholine) and increase sweat production. You may experience mild burning or tingling sensations in the areas being stimulated. 

Cardiovascular autonomic test with head-up tilt

During this second part of the autonomic test, we record your blood pressure and heart rate using an electrocardiogram (ECG). This part also includes recording other physiologic functions, such as production of carbon dioxide and cerebral blood flow velocity. This test involves performing the simple maneuvers described below.


1. Deep breathing 

This test examines how the heart rate responds to breathing slowly and deeply for 1.5 minutes at a rate of six breaths per minute. 


2. Valsalva maneuver

This test involves blowing forcefully into a mouthpiece against a closed airway. The Valsalva maneuver examines how the body compensates for changes in the amount of blood that returns to the heart. 


3. Head-up tilt

This test evaluates your blood pressure, heart rate, cerebral blood flow velocity, carbon dioxide levels and breathing rate in response to standing up. To check your cerebral blood flow velocity during head-up tilt, we will place a sensor called a transcranial Doppler on your temple to evaluate changes in blood supply to the brain. You will start by lying on a stretcher-like table, relaxing and breathing normally, with straps attached around your abdomen and legs. We will tilt the table up to a 70-degree angle for up to 45 minutes to reproduce your symptoms in a controlled setting while continuously monitoring your blood pressure, heart rate, cerebral blood flow velocity, carbon dioxide and breathing rate. If you experience symptoms — such as lightheadedness, weakness or feeling faint (known as pre-syncope) — we will tilt the table back to the lying position.


4. Catecholamine blood test

This test evaluates plasma concentrations of substances called catecholamines that regulate heart rate and blood pressure (e.g., norepinephrine and epinephrine). You will lie down in a stretcher-like table, relaxing and breathing normally and after 30 minutes blood will be drawn to obtain baseline serum concentrations of catecholamines. Baseline heart rate and blood pressure will be also measured while you are lying down. You will stand up for up to 20 min and heart rate, blood pressure and serum concentrations of catecholamines will be measured.

Preparing for autonomic testing

To prepare for your autonomic test, please follow these instructions: 


  • Once your test is scheduled, you will receive a list of medications that may affect the results of the test. You will be asked to discuss your medications with your physician. 
  • No nicotine (cigarettes) for eight (8) hours before the test. 
  • No caffeine (coffee, cola, energy drinks, tea, etc.) for eight (8) hours before the test. 
  • No alcohol the evening before the test. 
  • No medical or recreational marijuana for at least three (3) days prior to test. 
  • Eat and drink normally for 24 hours prior to testing and make sure you are hydrated before your test. 

Risks of autonomic testing

Some people may faint or collapse during the head-up tilt. When a patient’s symptoms and continuous recording of heart rate and blood pressure suggest pre-syncope (near fainting), the patient will be tilted back to a flat position immediately.

Autonomic testing results

Physiological measurements will be obtained in both parts of the test (the QSART and the cardiovascular autonomic test with head-up tilt) to determine evidence of dysautonomia.


The results can help physicians diagnose, evaluate, monitor and treat disorders of the autonomic nervous system, including:



Your physician will discuss your test results with you and let you know the next steps

Autonomic testing locations

We perform autonomic testing at the Autonomic Neurology Lab located in the Division of Neurology at the John R Anderson V Medical Pavilion in La Jolla.