Is Nasal Expiratory Resistance An Alternative to CPAP and Oral Appliances? Can The NERA Appliance be used with Oral Appliances?

An extremely interesting abstract can be foun in the Sleep Abstract Supplement “A RANDOMIZED CONTROLLED TRIAL OF NASAL EXPIRATORY RESISTANCE AS A TREATMENT FOR OBSTRUCTIVE SLEEP APNEA” by Berry RB1, Massie C2, Kryger . In their article they talk about the urgent need for alternatives to CPAP because of the dismal compliance to CPAP. They state ” Positive airway pressure (PAP) is an effective treatment for patients with obstructive sleep apnea (OSA) but adherence to treatment is only around 50%. Upper airway surgery and oral appliances may be effective in some patients. However, other treatment alternatives for OSA are urgently needed.”

Oral appliances ( are extremely effective in treating most mild to moderate cases of sleep apnea and are considered an alternative to CPAP for severe apnea when patients do not tolerate CPAP. Surgery is no longer considered a first line treatment for Sleep Apnea but is a valuable adjunctive procedure.

The authors report on “two pilot studies of 24 and 34 patients with OSA found that a nasal expiratory resistance appliance (NERA) significantly reduced the apnea-hypopnea index (AHI)” The appliance used was the NERA (ProventĀ®, Ventus Medical, Inc.) which consists of “two expiratory resistance valves each covering one nostril and held in place by anadhesive tape. The valves have negligible inspiratory resistance but have sufficient expiratory resistance to create a back pressure.”

” Analysis of subgroups of mild, moderate, and severe OSA patients was performed and the median improvement
was > 50% in all groups. For example, in the severe OSA group (N =17) the median AHI fell from 48.2 to 18.9 events/hour. ” The appliance appears to be highly effective when used alone. The authors concluded that: “The nasal expiratory resistance appliance resulted in a statistically and clinically significant reduction in the AHI in a group
of patients with mild to severe OSA.

This is an extremely exciting article because the next step is to combine the NERA with oral appliances which could give patients who do not get complete relief of apnea from oral appliance a combination therapy.

The majority of mild to moderate sleep apneic patients do extremely well with just an oral appliance however combining these two therapies may be the perfect answer for the 60% of patients who do not tolerate CPAP.

It is curious that the NERA appliance increases nasal expiratory resistance compared to the Oasys appliance that actually dilates the nasal passage. Is the effectiveness related to increased exchange of oxygen breathing out against resistance. It is well known that respiration requires resistance to achieve oxygen exchange and not just tidal volume air movement.

Other oral appliances can overly reduce nasal resistance and this may be a cause of breakthru central apnea when there is insufficient CO2 to stimulate breathing reflex.