Dichotomous physiological effects of nocturnal external nasal dilation in heavy snorers: the answer to a rhinologic controversy?

The purpose of this article was to study the impact of external dilation on nasal airway dimensions, sleep architecture, and snoring. Eighteen heavy snorers without severe obstructive sleep apnea syndrome (mean apnea-hypopnea index (AHI) 9.3) reporting nocturnal nasal obstruction were enrolled in a randomized (controlled) cross-over study, evaluating subjective and objective effects of external nasal dilation (Breathe Right, 3M). The active dilator was also worn during a one-week pretrial run-in period. Polysomnography, recording of snoring sounds, and repeated acoustic rhinometry were performed on two consecutive nights, one with the active dilator and one with a placebo strip. The significant subjective improvement reported during the run-in period compared to the preceding period without dilator (p < 0.01), remained only for nasal patency (p < 0.05) when comparing the two nights in the sleep laboratory. The nasal dimensions increased significantly (p < 0.001) with the active dilator compared to placebo, both in the evening and the next morning. In a subgroup (n = 6) of habitual snorers (AHI < 10) with severe morning obstruction (combined minimal cross-sectional area < 0.6 cm2), external dilation significantly improved the mean sleep PaSO2 (92.4 --> 96.7) and the percentage of sleep with a PaSO2 < 95% (49.9% --> 4.9%) (p < 0.05). In this subgroup there was a trend toward reduction in (7.4 --> 5.4) (p = 0.06), whereas the AHI increased significantly in the group of 12 with larger nocturnal nasal dimensions (p < 0.05). Duration and intensity of snoring remained unchanged regardless of the subgrouping. Objective beneficial effects were restricted to nocturnal oxygen saturation and AHI in a subgroup of habitual heavy snorers identified by repeated acoustic rhinometry, in whom external dilation objectively relieved marked nocturnal nasal obstruction. This finding may provide a logical explanation for the conflicting results of medical, surgical, and mechanical expansion of the nasal dimensions on snoring and sleep disturbances. (American

Does the oral device Noiselezz prevent sleep apnoea?

Both snoring and apnoea are caused by the collapse of soft tissue in the upper airways during sleep. Increasing the cross-sectional area of the airways in these segments by moving the mandible and/or the tongue forward stabilizes the upper airways in obstructive sleep apnoea syndrome (OSAS) patients. The aim of this study was to determine the effect of Noiselezz, which is an oral appliance of the mandibular advancing type, designed for easy use. Twenty-one patients, all men (aged 50.6 +/- 10.4, body mass index 26.5 +/- 3.3) were included in the study. Polysomnography (PSG) was performed before the patients started using Noiselezz. After a period of 2 weeks accustomizing to the oral device, the patients had another PSG performed with Noiselezz inserted. We found no significant differences in total sleep time, percentage of time spent snoring, duration of rapid eye movement (REM) sleep, slow-wave sleep, inter-sleep wake and sleep efficiency, apnoea/hypopnoea index (AHI) or lowest measured oxygen saturation after apnoea (minSaO2). No significant differences were found in the localization of obstructions or intrathoracal inspiratory pressure with and without the use of the Noiselezz oral device. Three patients (14%) reported satisfaction with treatment by the oral device. All three continued to use Noiselezz as treatment. The rest of the patients (86%) either did not tolerate the device at all or tried it for a period and then requested alternative treatment (n = 12). Most patients found the oral device "Noiselezz" inconvenient to use, and our results show that the device has little or no effect on snoring and sleep apnoea.

Diagnosing respiratory events and tracing air flow by internal thermistors.

We have developed a new method to measure flow in patients with sleep-related breathing disorders (SRBD). These flow sensors are modified thermistors located in the same sensors we use for pressure measurement in the upper airways to find the obstructive segments during apnoeas. The aim of this study was to test if using internal thermistors as indicator of air flow has advantages compared with the external thermistor method in detecting respiratory events. A total of 50 consecutive patients with an apnoea-hypopnoea index (AHI) of more than 15 were studied. A standard nocturnal polysomnography (PSG) with both internal and external thermistors was performed in all patients. To estimate the patients' AHI, a detailed analysis viewing all parameters except external and internal thermistors was performed. This was followed by an analysis viewing only internal thermistors signals indicating airflow in the pharynx, and finally an analysis viewing only external thermistor signals indicating air flow at the mouth and nose. Mean AHI measured by the three methods showed 49.8 (SD 23.4) by the PSG, 47.8 (SD 24.9) by internal thermistors alone, and 31.5 (SD 22.2) by external thermistors. There was no statistical difference between AHI detected by PSG and internal thermistors, but highly significant differences between PSG and external thermistors (p < 0.001). The external thermistors missed an average of almost 20 respiratory events per hour.

Tracing air flow and diagnosing hypopnoeas in normal subjects.

Hypopnoea is a type of sleep-related breathing disorder (SRBD), and the apnoea plus hypopnoea index (AHI) is usually computed to diagnose this condition. We introduce a new method to diagnose flow with internal thermistors located on the same sensors as we use to diagnose obstructive segments in patients with sleep-related breathing disorders. The aim of this study is to investigate whether internal thermistors are reliable for diagnosis of hypopnoeas. Fifteen volunteers participated in a prospective comparative study in healthy subjects without SRBD. We simultaneously measured minute ventilation by a pneumotachograph and indirectly air flow by internal thermistors in awake subjects was manually analysed from both the pneumotachograph and the internal thermistors. We found a close agreement between the different methods for percentage reduction in air flow both for the hypopnoea and the apnoea data. The mean difference between the percentage reduction in flow from normal breathing to hypopnoea measured by the pneumotachograph and the internal thermistors lying supine was 3.8% (SD 7.4). In the lateral position the corresponding figures were 1.0% and 4.6. This study in awake, normal subjects indicates that internal thermistors are as reliable as the pneumotachograph in diagnosing hypopnoeas and we believe that the reliability of this monitoring method is adequate for clinical use.

Internal thermistors in differentiating between oral and nasal breathing during sleep.

To select patients with sleep apnoea hypopnoea syndrome (SAHS) who will benefit from surgery, we use information from four different pressure sensors in the upper airways and oesophagus during polysomnography (PSG). These pressure sensors also have the ability to act as internal thermistors and can hence indirectly measure flow as well as pressure. This new method for measuring flow has proven to be very accurate for scoring hypopnoeas as well as apnoeas. The aim of this study was to determine whether the flow and pressure sensors located in the epipharynx, oropharynx and hypopharynx could differentiate between nasal and oral breathing. The design was a prospective cross-over study in 124 patients referred to the hospital for SAHS diagnosis. The awake patients were asked to breathe first through the nose and then through the mouth while the nose was blocked with a clip. A standard nocturnal PSG with pressure and flow measurement in the upper airways was performed in all patients. The procedure was repeated in a lateral position, and again the next morning in 32 of the patients. Reduction in flow signals from the nose was calculated, and a paired t-test was performed for statistical analysis. The difference between nasal and oral breathing was quite distinct in the flow tracings from the internal thermistors. The mean reduction in nasal flow signals when changing from nasal to oral breathing was 83.7% (SD 14.5, p < 0.0001). The same was seen in a lateral position, 82.2% (SD 16.4, p < 0.0001). Testing for changes in properties of the internal thermistors revealed no significant difference between the reduction in flow when the test started and after the patients had slept the whole night (p > 0.1). It is possible to differentiate between nasal and oral breathing using internal thermistors.