What is the QSART?

The QSART (Also known as the QSWEAT) is short for the “Quantitative Sudomotor Axon Reflex Test”. The goal of this test is to get a better understanding of a person’s nerve/sweat function, which can be tested by stimulating their body with electricity and collecting data on how it sweats in response. This specific body mechanism is a window for doctors to look into the autonomic nervous system, which is the system that controls the bodily functions that happen automatically, like breathing, heart rate, blood pressure, digestion, sweating, pupil dilation, and more. 

The QSART can be used for a wide range of diagnostic testing, but in the context of a patient with postural orthostatic tachycardia syndrome (POTS), the results can help further define what kind (or subtype) of POTS a patient has and what type of treatment might be best suited for the circumstances. Some POTS patients have nerve deterioration that causes their body’s inability to maintain circulation and blood flow, while others have POTS because of lower than normal blood volume, excessive sympathetic (fight-or-flight) response, deconditioning, central sensitization, or other reasons. Each subtype has its own characteristics, as well as secondary or tertiary symptoms that can be helpful to know the origin of, and the QSART can help figure that out. 

Why did I have the QSART test done?

I went to Mayo Clinic in Rochester, MN to be evaluated for POTS that was not responding to lifestyle changes and was unable to be treated by beta blockers (read about my experience with beta blockers here). I was referred there in order to have a more comprehensive evaluation completed, and part of the autonomic reflex screen was the QSART test.  

As I approached the testing day, I really wished I could sit down with someone who had experienced the test in order to help me set expectations and mentally prepare myself. If you’re in a similar boat – welcome. I hope that by sharing my experience I can be an encouragement to you as you navigate this health journey.

What was the test like?

First, let me tell you that this test was easier than expected, and that I would 100% be willing to do it again. In total honesty, in the days leading up to this tests I lost a bit of sleep overthinking, worrying about, and researching this test to try and calm my anxious nerves. Having a somewhat strong fear of electricity (from an electrical injury as a kid), the idea of having electricity flowing through my body in a medical environment really bothered me. But my takeaway was positive, I felt SO brave upon successful completion, and I am now here to tell you that YOU can do it too. 

Here’s a play-by-play of what it was like:

First, I entered the testing room with two autonomic techs, and was asked to take off my shoes and socks, hop up on the table, and lay down. They cleaned my skin, and then placed four small plastic capsules on my arms and legs, attached by a plastic band (kind of like with a hospital bracelet). They were all on the same side of the body – one went on my wrist, one on each side of my calf, and one on the top of my foot. They filled each one with liquid (acetylcholine) using syringes that were attached to each one so that the liquid was sitting on top of my skin but contained within the capsule (no needle prick here – it was just for getting the liquid where it needed to go without leaking). 

Once they had the capsules in place, they set up the electricity-delivering electrodes (like a small metal disk) which were connected to an electrical box on the counter. They placed each one on top of a soaking wet paper towel, and fastened them next to the capsule using a band around each limb.

I kind of wonder if the wet paper towel helped distribute the electricity more evenly, but that would just be my guess. It was very intriguing nonetheless.

When they had gathered their baseline data (by having me lie still for a few minutes), they turned on the electrical stimulation. Over a second or two, I began feeling tingles in my muscles on that half my body. Not everywhere all at once, but there would be a prick here, and a prick there, and general white noise of warm and sharp prickles kind of everywhere. If the nurse asked me a question or I thought about something else, the feeling could be tuned out, but when I sat in silence it was much more noticeable. It was not a classically painful feeling, kind of like burning nettle, or like when your leg goes numb. On a scale of 1-10 I would say it was somehow simultaneously a 2 and a 6, but in a tolerable sort of way. 

The test was exactly five minutes, and then they turned off the stimulation. I spent another five minutes there as they gathered more data (and the feeling/pain started fading away), and then they took all of the electrodes and capsules off. I had red marks where each one had been, but they healed within a day and didn’t cause any lasting discomfort. 

Summary

As someone who was having significant distress about my variety of symptoms and lack of being able to control them, the opportunity to be evaluated for autonomic dysfunction and have the QSART analysis was an absolute blessing. While I had abnormal data throughout the other tests, the QSART was one thing that showed normal function. This gave us important information about my kind of POTS, and helped point us in the right direction for treatment options.