CPET – Cardiopulmonary Exercise Test

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Workwell Teams up with STAT Health

Workwell Foundation recently teamed up with Daniel Lee, the co-founder and CEO of STAT Health, to test an exciting new in-ear wearable device that tracks blood flow to the head. 

Many people with ME/CFS and long COVID report worsening orthostatic symptoms (i.e., when upright) during post-exertional malaise (PEM) crashes. Workwell and STAT Health hope to understand whether blood flow to the head is reduced during PEM and if this index helps explain the worsened orthostatic symptoms that many report. 

Our research pairs two-day cardiopulmonary exercise testing (CPET) with the new in-ear STAT device to observe changes in blood flow to the head before and after stress using the 24-hour test-retest methodology we pioneered. As indexed by STAT’s new technology, blood flow to the head has been shown to correlate with Cerebral Blood Flow (CBF) changes induced by standing.

Why is OI important?

If you feel worse when sitting upright or standing, you may have orthostatic intolerance (OI). STAT Health designed its new device to track and better manage this condition.

Orthostatic intolerance (OI) is an inability to withstand an upright posture due to impaired cardiovascular autonomic function. Typically, our bodies can counteract the effects of gravity by altering blood pressure and heart rate to ensure enough oxygenated blood continues flowing to the upper body. When the part of the nervous system regulating heart rate and blood pressure (i.e., the autonomic nervous system) isn’t working correctly, sufficient oxygen fails to reach the brain, resulting in dizziness, shortness of breath, and fatigue. 

OI is prevalent in fatiguing illnesses such as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), long COVID, and postural orthostatic tachycardia syndrome (POTS). Estimates for adults with long COVID in the United States alone are as high as 18 million.

Orthostatic intolerance can be a disabling condition limiting how long people can be upright. OI is also a safety concern because it can impair cognition and cause fainting. People with OI struggle to work, drive, socialize, or do upright activities. 

What causes OI

Several problems with the autonomic nervous system – called dysautonomia – can cause OI. These include postural tachycardia syndrome (POTS) – a condition in which the heart rate increases abnormally upon standing in an attempt to keep blood pumping to the upper part of the body. POTS can occur when vessels do not constrict adequately when upright, which may lead to blood pooling in the lower extremities. POTS can also arise when autoantibodies attack receptors interacting with the neurotransmitters that orchestrate the heart rate response. 

OI can also occur with another type of dysautonomia called orthostatic hypotension. In orthostatic hypotension, the body fails to maintain blood pressure when moving from lying down to standing. Usually, blood pressure remains stable when standing, but with orthostatic hypotension, blood pressure drops. When this occurs, insufficient oxygen reaches the brain, making people feel dizzy or faint. 

Reduced cerebral blood flow is also related to dysautonomia

Another explanation for OI that has captured much attention is a drop in cerebral blood flow (CBF) upon standing. Recent research using Doppler ultrasound in ME/CFS and long COVID has shown that even those without POTS or orthostatic hypotension can experience significant drops in blood flow to the head and cause symptoms of OI. 

Two main explanations for the observed CBF reductions in ME/CFS include preload failure and hypocapnia. Hypocapnia leads to a drop in CO2 in the blood, causing blood vessels in the brain to constrict, limiting blood flow to the head.

How the STAT device can help manage OI

The new STAT device can help manage OI in several ways. The device pairs with a smartphone app and provides information about blood flow to the head, interpreted in an easy-to-understand “Flow Index.”. It also measures heart rate, an index of blood pressure, and time spent upright. Because dysautonomia is a condition that fluctuates, the STAT device allows people with OI to pace activities and evaluate how specific treatments impact blood flow to the head. 

The device is small, noninvasive, and nestles in the outer ear. Users can wear it 24/7, including while sleeping and showering. STAT has clinically tested their new device against standard methods for measuring cerebral blood flow, including transcranial Doppler and extracranial Doppler of the carotid artery at research institutions such as Johns Hopkins and Duke. 

The device uses an optical sensor to track blood flow to the head, a relative blood pressure index, and heart rate. Placing the device in the outer ear helps avoid inaccuracy problems in optical sensors worn on the wrist or finger. This location enables the new Flow and Pressure Indices and captures better motion-resistant heart rate data throughout daily activities. 

Daniel Lee, the entrepreneur and founder of STAT Health, has extensive experience with in-ear devices. He developed the technology used in the Bose Sleepbuds. After seeing his father struggle with fainting, he got the idea to create a device to help millions of people manage low blood flow to the head. 

Pre-orders are now open for US residents, with devices estimated to ship July–September 2024.

CPET with Workwell

The two-day CPET offered by Workwell Foundation allows patients to understand better if they have conditions associated with OI and reduced cerebral blood flow, such as ventilation problems that cause hypocapnia and a blunted heart rate (i.e., chronotropic incompetence). Two-day CPET also provides valuable information on cardio-metabolic and pulmonary function. 

To schedule a 2-day CPET, please contact Workwell Foundation at(661) 466-2545, email us at info@workwellfoundation.org, or visit our webpage.  For a brochure on our services, please click here.