Does Rapid Eye Movement Sleep Aggravate Obstructive Sleep Apnea?

Correlation between short-time and whole-night obstruction level tests for patients with obstructive sleep apnea

Identification of obstructive level is crucial for successful surgical outcomes in patients with obstructive sleep apnea (OSA). Unfortunately, most of the dynamic airway evaluations are performed for a short duration under drug-induced sleep; therefore, it is uncertain whether they represent airway events that occur during a whole night of sleep. This study was aimed to evaluate the correlation between obstructive levels that were identified by a short-time and a whole-night test in patients with OSA. Total 101 patients with OSA underwent drug-induced sleep fluoroscopy (DISF) and pressure manometry (PM). For DISF, the obstructive pattern was classified into one of three groups: soft palate, tongue-based, and a combined obstruction. PM was used to measure the proportion of retroglossal events out of total whole-night obstructive events in each patient. The mean age of the patients was 43.8 years. The obstructive pattern was identified as soft palate in 56 patients, combined in 38 patients, and tongue-based in 7 patients following DISF. Results from PM showed that the mean percentage of retroglossal obstructive events was 31.2 ± 30.7%. The average proportion of retroglossal obstructive events that were identified by PM in patients with soft palate, combined, and tongue-based obstruction was 27.2%, 32.1%, and 59.0%, respectively (p = 0.033). There are limitations of evaluating obstructive events that occur during a whole night with short-time tests. Surgeons should be aware the possibility of disagreement in the obstructive level between short-time and whole-night tests.

Normal and obstructive breathing physiology during sleep

PURPOSE

To estimate the severity of flow limitation in patients with OSA, the number of breaths with flattened inspiratory flow curves should be identified. Attempts to do a quantitative analysis of the flattening degree for all breaths in a nighttime recording have failed up to now.

METHODS

SOMNOmedics (Randersacker, Germany) developed an automated flattening analysis parameter called the obstructive coefficient (OC). Polysomnographic measurement including esophageal manometry was done in 25 subjects (10 healthy, 9 patients with mild OSA, and 6 with severe OSA). For each breath, the data couple of OC and esophageal pressure (EP) was used for analysis.

RESULTS

Data couples of OC and EP were recorded for 104,608 breaths. Airway patency histogram profiles for each study group showed no remarkable differences between each other. Increase in EP with increasing RDI was identified as the only marker of OSA severity. A strong shift was observed in N3 breaths from maximum OC/lowest EP values in healthy subjects to low OC values in association with maximum EP values in OSA.

CONCLUSION

The OC enables quantification of all breaths of a nighttime recording according to their degree of flattening. The relation of strong limited to less strong limited breaths is the same across the three study groups. The analysis of the corresponding EP to a given OC value for each study group identified the EP that is necessary to cause a given flow as the only parameter that discriminates degrees of severity of OSA. The trial registration number is DRKS00018095 from 2019 to 10-09.

Update on Persistent Excessive Daytime Sleepiness in OSA

OSA is a highly prevalent sleep disorder, and subjective excessive daytime sleepiness (EDS) is the cardinal symptom for which many individuals seek medical advice. Positive airway pressure (PAP) devices, first-line treatment for OSA, eliminates EDS in most patients. However, a subset of patients suffers from persistent EDS despite adherence to therapy. Multiple conditions, some reversible, could account for the residual sleepiness and need to be explored, requiring detailed history, review of PAP data from the smart card, and sometimes additional testing. When all known causes of EDS are excluded, in adequately treated subjects, the purported mechanisms could relate to long-term exposure to the OSA-related sleep fragmentation, sleep deprivation, and hypoxic injury to the arousal system, shifts in melatonin secretion, or altered microbiome. Independent of the mechanism, in well-treated OSA, pharmacological therapy with approved drugs can be considered. Modafinil is commonly prescribed to combat residual EDS, but more recently two drugs, solriamfetol, a dual dopamine-norepinephrine reuptake inhibitor, and pitolisant, a histamine H3 receptor inverse agonist, were approved for EDS. Solriamfetol has undergone randomized controlled trials for treatment of EDS associated with both OSA and narcolepsy, exhibiting robust efficacy. Solriamfetol is renally excreted, with no known drug interactions. Pitolisant, which is nonscheduled, has undergone multiple RCTs in narcolepsy, showing improvement in subjective and objective EDS and one OSA trial showing improvement in subjective EDS.