What is Upper Airway resistance Syndrome (UARS)?

Upper airway resistance syndrome is a disease that most physicians either have never heard of or don’t believe exists …

UARS – Upper airway resistance syndrome

I recall seeing a young lady of around 20 some years ago, who was suffering from chronic tiredness. The symptoms had been attributed to college, dancing or psychology. An overnight sleep lab test revealed no obvious physical problems and indicated that she had no obstructive sleep apnea – how could she have, her events were less than 5 per hour  – she was young, female, fit, of ideal weight, slim and exercised. The sleep lab felt the problem was psychological.

Subjects with these isolated complaints of chronic daytime sleepiness are usually classified as “idiopathic hypersomniacs” and treated symptomatically using sleeping tablets as required.

In a group of these sufferers, sleep is fragmented by very short sleep arousals throughout the night. These short arousals are usually ignored in sleep analyses, but their impact is significant.

Upper airway resistance syndrome, (UARS) is a more recent entity and describes patients with symptoms of obstructive sleep apnea (OSA) and polysomnographic (PSG) evidence of sleep fragmentation but who have minimal obstructive apneas or hypopneas (Respiratory Disturbance Index less than 5, and do not exhibit oxygen desaturation in the blood.)

Symptoms of UARS

Symptoms of UARS are similar to those of obstructive sleep apnea, fatigue, daytime sleepiness, un-refreshing sleep, and frequent awakenings during sleep are the most common symptoms.

Unfortunately, there is no good way to diagnose UARS without going to a sleep lab that specializes in, and is specifically looking for it.  

Unlike sleep apnea, which actually prevents air from getting into your body and causes the oxygen levels in your blood to drop, UARS does not result in this nor even necessarily a decrease in airflow.

Investigations in non-obese individuals reveal repetitive increased respiratory effort terminated by transient arousals, but without associated airway collapse, hypoventilation, or oxygen desaturation.

These arousals are directly related to an abnormal increase in respiratory efforts during sleep.

One way to view UARS is to say that OSA is caused by a blockage (often the tongue) while UARS is more due to an increase in the collapsibility of the airway which causes further sleep fragmentation without blockage, so it becomes a vicious cycle with a strong physiologic component, without the typical findings of OSA (male, obese, age, etc.)

Testing for UARS

It is simply the increased work of breathing, which tends to repeatedly disrupt sleep during the night. So, if you are going to have a sleep study, check with the lab before doing so to be sure that they will be checking for UARS and know how to do it. 

Newer technologies that look for pressure changes in your nose or even alterations in breathing or pulse wave signals is already making this testing more user-friendly. Alas, I was unable to be heard when it came to the young lady I mentioned as I was the dentist in the group.

If you are unable to go to a sleep clinic, there is a simple ‘nose test’ to see if you are suffering from nasal resistance. Looking in a mirror, press the side of one nostril to close it.

With your mouth closed, breathe in through your other nostril. If the nostril tends to collapse, try holding it open with the flat side of a teaspoon handle. Test both nostrils. If breathing is easier with your nostril held open, using nasal dilators or strips when sleeping

Snoring is not infrequently associated with these transient arousals however, snoring is not sufficient nor necessary for the identification of the clinical syndrome. It is probably present as there is still airflow, but of a more strained manner.

Both sexes appear equally represented. UARS is a distinct syndrome that occurs in a distinct population.

There is a false assumption that it forms a continuum between primary snoring and OSA. Any attempt to understand the differences between OSAS and UARS must be based on investigations in non-obese subjects, and must include sensitive measures of respiratory effort.

Association between UARS and FMS

Fibromyalgia (FMS) is a common syndrome in which a person has long-term, body-wide pain and tenderness in the joints, muscles, tendons and other soft tissues.

Studies have shown that the vast majority of fibromyalgia sufferers have undiagnosed UARS. When UARS is properly managed, fibromyalgia pain can be dramatically decreased. Chronic fatigue syndrome (CFS) is another syndromic association.

Although a mild decrease in airflow while sleeping may not seem like a big problem, it has been shown to disrupt sleep enough to cause and/or perpetuate CFS/FMS.

Therefore, keeping your airways open is critical. At least such findings are making credible, those symptoms which were once thought to be solely psychological in origin.

Management of UARS

Over the years a simple nasal dilator called Nozovent (available online) has proved to be one of the most popular and easy to use devices to enhance nasal breathing.

This device is not just for snorers but can be used by anybody who suffers from nasal resistance. Another easy option is “Breathe Right” nose strips. 

UARS – Conclusions

UARS is a syndrome of increased upper airway collapsibility during sleep. The upper airway collapsibility during sleep of patients with UARS is intermediate between that of normal subjects and that of patients with mild-to moderate OSA although it may be a mistake to assume that it is a continuum of OSA

Today, the clinical picture of UARS is better defined. We have learned that patients usually seek treatment with a somatic functional syndrome rather than sleep-disordered breathing or even a disorder of excessive daytime sleepiness.

The term upper airway resistance syndrome (UARS) was coined to describe a group of patients who did not meet the criteria for diagnosis of OSA and thus were left untreated.

UARS – How far have we come in the last 10 years?

Today however, we have moved forward little, most of the patients with UARS remain undiagnosed and are still left untreated.

Therefore, most of these patients are seen by psychiatrists. In addition, recent technologic advances have allowed a better recognition of the problem. We have learned that OSA is associated with a local neurologic impairment that is responsible for the occurrence of these airway compromises.

In contrast, patients with UARS have an intact local neurologic system and have the ability to respond to minor changes in upper airway dimension and resistance to airflow.

UARS – Summary 

The clinical presentation of patients with UARS is similar to the presentation of subjects with functional somatic syndrome (FSS). Functional somatic syndromes are characterized by ambiguous, non-specific symptoms that appear in otherwise-healthy people. Overlap in symptoms exists across diagnoses, including gastrointestinal issues, pain, fatigue, cognitive difficulties, and sleep difficulties.

To diagnose UARS, nocturnal polysomnography (PSG)  should include additional measurement channels and an open mind.

Untreated UARS individuals can present low quality of life and cardiovascular consequences. Sleep and daytime symptoms, such as fatigue, insomnia and depressive mood. UARS patients have a worse sleep quality, more fatigue and a worsened early morning sustained attention compared to those with mild OSA.

UARS – The future

Currently, there are few well designed studies available of UARS treatment, CPAP has been the primary therapy prescribed, but its effectiveness has been limited because of low patient compliance and there are no randomized controlled trials evaluating this type of treatment in UARS patients. Oral appliances seem to be an effective option, but only case reports and small case series have been reported, and the efficacy of these devices is not yet established for those with UARS. This is clearly a work in progres.

Progress will be associated with physician’s and other healthcare professionals interest and willingness to see sleep as a complex process in which many problems may exist either individually or in combination. Also that we still no little of the mysteries of sleep.

Good sleep is crucial to good health and longevity.

Dr. Stephen Bray 2020

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