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Effect of Nasal-Valve Dilation on Obstructive Sleep Apnea^*

^* From Krankenhaus Kloster Grafschaft (Drs. Schönhofer, Brünig, Wehde, and Köhler), Zentrum für Pneumologie, Beatmungs - und Schlafmedizin, Schmallenberg-Grafschaft, Germany; and Department of Respiratory Medicine (Dr. Franklin), University Hospital, Umeå, Sweden.

Correspondence to: Bernd Schönhofer, MD, PhD, Krankenhaus Kloster Grafschaft, Zentrum für Pneumologie, Beatmungs- und Schlafmedizin, D-57392 Schmallenberg-Grafschaft, Germany; e-mail: Bernd.Schoenhofer{at}t-online.de

	Abstract

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Objective: Nasal-valve dilation reduces nasal resistance and increases air flow. It is possible that this mechanism prevents hypopharyngeal collapse and sleep apneas. We investigated the effect of a plastic device (Nozovent; Prevancure AB; Västra Frölunda, Sweden)—which dilates the nasal valve—on patients with obstructive sleep apnea (OSA).

Design: Prospective interventional study.

Subjects: Twenty-six consecutive patients with OSA were included (22 men; mean ± SD age, 54.8 ± 11.3 years; respiratory disturbance index [RDI], 34.4 ± 18.5 events/h; body mass index, 31.6 ± 5.7 kg/m²).

Intervention: The nasal dilator was inserted during sleep into the nares and fitted to exert a dilating force on the nasal valves by means of its elasticity.

Measurements: Polysomnographic studies were performed before and after 1 month of treatment. A responder is defined as one with a reduction in RDI to < 50% of the baseline value and RDI of 10 events/h during treatment.

Results: Five patients dropped out. As a result, only 21 patients were analyzed. Four patients responded, and 17 patients were nonresponders. In the whole population, neither the mean values for respiration during sleep nor sleep staging changed significantly with the device.

Conclusions: The investigated nasal dilator had no effect on sleep-related breathing disorders in patients with moderate to severe OSA. The reduction in nasal resistance does not prevent hypopharyngeal obstruction.

Key Words: nasal congestion • nasal obstruction • nasal resistance • sleep apnea syndrome • snoring

	Introduction

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Increased nasal resistance may induce sleep-related breathing disorders and disturbed sleep.^{1 2 3} It has been shown that several devices, including nasal-valve dilators (Nozovent; Prevancure AB; Västra Frölunda, Sweden), reduce nasal resistance and improve nasal breathing.^{4 5} The Nozovent device consists of a plastic bar that dilates the anterior part of the nose, the valve region, in order to increase the air flow. Its inventors aimed to eliminate snoring and sleep apnea using the device.^{6 7 8 9} They have tested Nozovent in a number of studies and report an excellent effect on nasal resistance, snoring, and sleep apneas.^{6 7 8 9} However, Metes et al⁵ did not find any effect on snoring, apneas, hypopneas, or arterial oxygen saturation (SaO₂) in a small sample of patients, despite a reduction in nasal resistance.

Nozovent is sold at pharmacies and is distributed worldwide as a treatment for different indications, such as compromised nasal breathing, nocturnal asthma, dryness of mouth, snoring, and sleep apnea. The potential market is huge, since habitual snoring occurs among 15% of middle-aged adults and occasional snoring among 30%.¹⁰

In this study, we aimed to investigate whether Nozovent has the effect on snoring and sleep apnea that has previously been reported among patients suffering from obstructive sleep apnea (OSA).^{6 7 8 9}

	Materials and Methods

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Measurements
Standard polysomnographic recordings were made using ED-sleep (MAP; Martinsried, Germany). The recordings comprised two EEG derivations (C₄-A₁ and C₃-A₂), two electro-oculograms, two electromyograms of submental and tibialis anterior muscles, and an ECG (modified V₂ lead). Respiration was monitored using oronasal thermistors, and thoracic and abdominal movements with inductive plethysmography. Body position and SaO₂ using finger oximetry were also recorded. A microphone placed below the larynx using a MESAM 4 device (MAP) monitored breathing sounds.

Sleep was rated manually in 30-s epochs according to the criteria defined by Rechtschaffen and Kales.¹¹ We determined sleep efficiency as the total sleep time divided by the total time in bed. Sleep latency was defined as the time from the start of the study (lights off) to sleep onset. Apnea was defined as a complete cessation of oronasal air flow for at least 10 s. Apneas were classified as obstructive when thoracic or abdominal movements were present. A central apnea was scored if a complete cessation of oronasal air flow lasting at least 10 s occurred in the absence of thoracoabdominal movements. A hypopnea was defined as a 50% reduction in the amplitude of the air flow waveform from a preceding stable baseline, associated with a decrease in SaO₂ of 4%. Several indexes of sleep-related respiratory abnormality were calculated. They included the apnea index (ie, the number of apneas divided by hours of sleep) and the respiratory disturbance index (RDI; ie, the number of apnea and hypopnea events per hours of sleep). The mean and nadir SaO₂ associated with an abnormal respiratory event during sleep were determined. The snoring index (SI) was calculated from the number of intervals between two snores that were > 11-s long but < 60-s long.

The effect on snoring produced by the nasal dilator was estimated by the bed partner according to a five-point questionnaire, as follows: no reduction, mild reduction, moderate reduction, moderate to high reduction, or complete abolishment of snoring sounds. Losing the nasal dilator during sleep was documented by the patients.

Daytime sleepiness was estimated according to the Epworth Sleepiness Scale (ESS).¹² The following were postulated as efficacy criteria of the investigated device: reduction in RDI to > 50% in comparison with the baseline value, and a posttreatment RDI of 10 events/h and/or subjective benefit and no relevant side effects.

The Nasal Dilator
The Nozovent device (Fig 1 ) consists of a plastic bar with two tabs on each end. It is designed to fit inside the nostril and dilate the nasal valves by means of its elasticity and thus decrease nasal resistance and improve air flow. The patients were told to use the device every night during the study period. Each patient was given the optimal size of the device (ie, small, medium, or large). Patients with reduced tolerance were instructed to apply the device at least 2 times/d in order to familiarize with the treatment.

View larger version (25K): [in this window] [in a new window] [Download PPT slide]   Figure 1.. The Nozovent nasal-valve dilator before insertion (top) and in position (bottom).

Patients were instructed to keep regular sleep-wake schedules and to abstain from alcohol for 1 week prior to both the baseline polysomnographic recordings and the follow-up study. To avoid first-night effects, the actual monitoring nights were preceded by one in-laboratory adaptation night with full recording equipment. The control polysomnography was performed 1 month after receiving the device.

The bed partners’ subjective ratings of the improvement in snoring (or not) were given in the end of the study period. Written, informed consent was obtained from all study subjects.

Statistical Analysis
Results were expressed as the mean ± SD. Wilcoxon signed-rank matched pairs test for nonparametric data was used for statistical comparison. A p < 0.05 was considered to be significant.

	Results

TOP Abstract Introduction Materials and Methods Results Discussion References

 
Twenty-six consecutive patients with OSA were included (22 men; age, 54.8 ± 11.3 years; RDI, 34.4 ± 18.5 events/h). Body mass index (BMI) did not change during the study (BMI before study period, 31.6 ± 5.7 kg/m²; BMI after study period, 30.9 ± 6.2 kg/m²).

Five patients were not followed up. Three of them were not willing to continue the study, since they lost the device (up to 10 times a night) despite trials to optimize the fitting of the device. One patient refused the readmission for unknown reasons. In the last case, the insurance company refused to reimburse the hospitalization.

There was no improvement in apnea frequency, SI, SaO₂, and sleep parameters in the whole population of 21 patients studied with respect to mean values ± SD (Table 1 ). The mild improvement of the ESS (from 8.9 ± 3.8 to 7.9 ± 4.5) seems not to be of clinical relevance.

View larger version (31K): [in this window] [in a new window] [Download PPT slide]   Figure 2.. RDI (mean ± SD) with and without the Nozovent device (Nozo) in the 17 nonresponders; ns = not significant.

Seven patients changed the size of the device during the study period in order to optimize the fit of the device. The device was, however, lost several times a night in 16 of 21 patients.

	Discussion

TOP Abstract Introduction Materials and Methods Results Discussion References

 
The main finding of this study was that the objective measurements of snoring and apneas during sleep were almost unaffected by the Nozovent nasal dilator. However, the majority of bed partners reported a mild reduction in snoring when their spouse used the nasal dilator. The slight decrease in subjective daytime sleepiness in the patients is probably clinically irrelevant. There is obviously a discrepancy between objective measurements of snoring in the sleep laboratory and the appreciation of bed partner.

Our findings support studies^{2 13 14 15} reporting that nasal resistance has no impact on the pathogenesis of OSA. Thus, both snoring and sleep apnea probably are caused by other factors, such as restrictive processes in the pharyngeal area, rather than increased nasal resistance. Accordingly, in a previous study,¹⁶ we did not find any effect of a nose plaster—another kind of nasal dilator—on snoring and apnea.

Neither we, in the present study, nor Metes et al⁵ found any objective effect on sleep apnea, and only a minor effect on snoring was seen with use of the dilator. On the other hand, in four studies performed by the inventor of Nozovent device, an excellent effect on snoring and sleep apnea was found.^{6 7 8 9} In the present study, we included only consecutive patients with sleep apnea. There is a lack of inclusion criteria in the four studies reporting an excellent effect with the device. In three of the studies, there is no information about any consecutive case series. From our point of view, it is not possible to explain the different results.

In conclusion, we do not recommend treatment with the Nozovent nasal dilator in patients suffering from OSA. The dilator has only a slight subjective effect on snoring, but no effect on objectively measured snoring and the other parameters of sleep-related breathing. Furthermore, when using a nasal dilator, it is possible that the bed partner’s appreciation of the reduced snoring may delay the initiation of the adequate treatment of sleep apnea.

	Footnotes

 
Abbreviations: BMI = body mass index; ESS = Epworth sleepiness scale; OSA = obstructive sleep apnea; RDI = respiratory disturbance index; SaO₂ = arterial oxygen saturation; SI = snoring index

Received for publication November 15, 1999. Accepted for publication April 21, 2000.

	References

TOP Abstract Introduction Materials and Methods Results Discussion References

 

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