Clinical Definition

A RERA is a sequence of breaths, lasting at least 10 seconds, characterized by increasing respiratory effort (e.g., as indicated by flattening of the nasal pressure waveform) that leads to an arousal from sleep. Crucially, a RERA does not meet the criteria for an apnea (complete blockage) or a hypopnea (significant partial blockage with oxygen desaturation).

These events are important because, despite not causing significant oxygen drops, they still fragment sleep due to the associated arousal, leading to symptoms like excessive daytime sleepiness.

Etymology & History

The concept of RERAs was introduced in the 1990s to explain the symptoms of patients who had significant daytime sleepiness but did not meet the criteria for OSA based on their AHI. This led to the definition of Upper Airway Resistance Syndrome (UARS).

Reference Values & Interpretation

Normal Values

There are no normal values for RERAs. They are considered abnormal respiratory events. Their count is included in the RDI.

Abnormal Values

An elevated number of RERAs (contributing to a high RDI) is considered abnormal and clinically significant, especially in symptomatic patients.

How It's Measured

Scoring RERAs requires an in-lab PSG with a nasal pressure transducer to detect the subtle flattening of the inspiratory airflow waveform, along with EEG channels to confirm the subsequent arousal from sleep.

Role in Diagnosis

RERAs are the defining feature of Upper Airway Resistance Syndrome (UARS). Their identification is essential to diagnose patients whose primary sleep-breathing problem is sleep fragmentation from respiratory effort, rather than hypoxia from apneas/hypopneas.

Role in Treatment

Patients with frequent RERAs often benefit from the same treatments as those with OSA, such as CPAP or oral appliance therapy. The goal of treatment is to reduce the RDI, which includes eliminating RERAs, thereby stabilizing breathing and consolidating sleep.

Associated Conditions

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Clinical Guidelines

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Latest Research & Updates

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The clinical importance of RERAs remains a topic of discussion. While they clearly cause sleep fragmentation, their long-term cardiovascular impact is less established compared to apneas and hypopneas associated with hypoxia. However, for symptomatic patients, treating RERAs is crucial for improving quality of life.