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* From the Klinik Ambrock (Drs. Randerath and Ruehle), Hagen, Department for Pneumology, Allergology and Sleep Medicine, University Witten/Herdecke, Witten; and Department of Orthodontics (Drs. Heise and Hinz), University Witten/Herdecke, Witten, Germany.
Correspondence to: Winfried J. Randerath, MD, FCCP, Klinik Ambrock, Klinik für Pneumologie, Allergologie und Schlafmedizin, Ambrocker Weg 60, D-58091 Hagen, Germany; e-mail: Winfried.Randerath{at}dland.de
| Abstract |
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30/h. Methods: In a randomized crossover study, 16 men and 4 women (mean ± SD age, 56.5 ± 10.2 years; body mass index, 31.2 ± 6.4; AHI, 17.5 ± 7.7/h) were treated for 6 weeks with each modality.
Results: In the initial phase, a significant improvement in AHI (baseline, 17.5 ± 7.7/h; ISAD, 10.5 ± 7.5/h [p < 0.05]; CPAP, 3.5 ± 2.9/h [p < 0.01]) and in breathing-related arousals (baseline, 8.9 ± 6.1/h; ISAD, 3.7 ± 3.3/h [p < 0.01]; CPAP, 1.4 ± 1.6/h [p < 0.01]) was achieved with both modalities. Considering all 20 subjects, after 6 weeks of treatment, normalization of the respiratory parameters was seen only with CPAP. However, 30% of the patients had a lasting reduction in AHI to < 10/h with the ISAD also. The patients considered the ISAD to be easier to use (scale of 1 to 6: ISAD, 1.8 ± 1.1; CPAP, 3.1 ± 1.5 [p < 0.05]), and indicated greater utilization of the device in comparison with CPAP.
Conclusion: Even in patients with mild-to-moderate OSAS, CPAP is the more effective long-term treatment modality. In the individual case, the better compliance seen with the ISAD may be advantageous.
Key Words: continuous positive airway pressure mandibular advancement device orthodontic appliances positive pressure ventilation sleep apnea, obstructive
| Introduction |
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Only few data obtained from prospective randomized studies comparing MADs with CPAP are currently available. Clark et al18 found a reduction in respiratory disturbances of 39% with an "anterior mandibular positioning device," and 50% with CPAP. However, the AHI with CPAP was reduced only to 11.15 ± 3.93/h.18 Moreover, comparison of the two treatment modes in this study was not done in randomized fashion. Ferguson et al19 performed a randomized crossover study with a nonadjustable oral appliance. Respiratory disturbances and daytime symptoms showed significantly greater improvement with CPAP than with an MAD.19 After 4 months of treatment using an adjustable anterior mandibular positioner, the same authors recorded a decrease in AHI from 25.3 ± 15.0 to 14.2 ± 14.7/h, corresponding to 44% of the baseline value.20 In seven patients, the AHI remained > 10/h. Although a clearly greater improvement in the respiratory disturbances was seen with CPAP, no relevant differences were observed between the two modalities in terms of sleep profile, and there was no improvement vs baseline in sleep profile. With regard to compliance, the oral appliance also proved to be clearly superior to CPAP treatment.20
In contrast to uncontrolled studies, which report large reductions in AHI, the above-mentioned controlled studies failed to find such a positive effect of an MAD on sleep-related disturbances. On the basis of these data, the use of MADs was recommended only in patients with nonobstructive snoring or mild sleep apnea.21
In severe OSAS, MADs should only be used if the patients refuse CPAP.21
Against this background, we therefore carried out a randomized crossover study to comparefor the first time, as far as we are awarean MAD with CPAP applied over the long term exclusively in patients with an AHI
30/h in accordance with the recommendations of the American Sleep Disorders Association (ASDA). Our aim was to investigate the effectiveness and acceptance of an adjustable orthodontic device permitting jaw movements in three dimensions (an intraoral sleep apnea device [ISAD]), in comparison with CPAP.
| Materials and Methods |
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30/h were admitted. Exclusion criteria were an AHI > 30/h, temporomandibular joint disorders, bruxism, and patients with gaps in their dentition precluding fitting of the device. We studied only patients with mild-to-moderate OSAS, so as to comply with ASDA recommendations.21
Patients with more severe OSAS were not included since MADs are recommended in this group only if CPAP is not accepted. Since the diagnosis of OSAS and the need for treatment were established for the first time in all participants, refusal of CPAP could not legitimately be used as an inclusion criterion. All patients gave their informed consent. The study was approved by the ethics committee of the University Witten/Herdecke.
Devices
The ISAD (IST; Hinz; Herne, Germany) is an oral appliance for the noninvasive treatment of sleep-disordered breathing. Two thin thermoplastic parts, worn on the upper and lower jaws, are connected by two adjustable telescopic guide rods (Scheu-Dental; Iserlohn, Germany) in the vestibule. The ISAD works by advancing and slightly depressing the mandible and tongue while imparting a slight vertical clockwise rotation. Prior to customizing the device, any pathology of the temporomandibular joints was excluded by a manual functional examination, with particular attention being paid to excursive movements. After obtaining an impression of the upper and lower teeth, the dentist determined the amount of mandibular advancement and the size of the bite opening with a construction bite obtained with the George Gauge instrument.22
The maximum forward protrusion of the mandible was measured, and this amount reduced to about two thirds before mounting the casts in the articulator23
(Fig 1
).
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5/h. The mean CPAP treatment pressure was 7.4 ± 0.9 cm H2O.
Design
Following the diagnostic polysomnographies, manual CPAP titration, and customized fitting of the ISAD, the patients underwent, in randomized crossover fashion, 1 night of polysomnography with CPAP (CPAP, first night) and 1 night with the ISAD (ISAD, first night), which was then followed by 6 weeks of home treatment with CPAP and 6 weeks with the ISAD or vice versa. During the initial 6 weeks of treatment with the ISAD, patients need to adapt to the device, so the amount of protrusion was not adjusted during this period. Eight patients began treatment with CPAP, and 12 patients began treatment with the ISAD. At the end of each period of treatment, polysomnography was carried out in the sleep laboratory (CPAP, 6 weeks; ISAD, 6 weeks), and the patients were interviewed to record the effect and acceptance of each of the modalities.
Polysomnography
The following parameters were recorded: submental or pretibial electromyography, EEG C4A1 or C3A2, electro-oculography, respiratory effort (thoracic and abdominal impedance plethysmography), respiratory flow (thermo-elements), CPAP pressure (pressure sensor signal at the mask), snoring (laryngeal microphone), and oxygen saturation (finger pulse oximetry). Body position was not recorded. The results of polysomnography were analyzed by chest specialists in accordance with the guidelines of Rechtschaffen and Kales and the ASDA criteria.24
25
Arousals were defined as respiration induced when they occurred at the earliest with the onset, at the latest 2 s after the end, of an apnea or hypopnea.
A hypopnea was defined as a reduction of flow or effort of 50% in comparison with baseline for at least 10 s or any reduction of flow and effort and a decrease in oxygen saturation of at least 4%. To quantify snoring, the number of epochs (30 s per page) with evidence of microphone signals for at least 2 s outside of movement artifacts were counted as previously described.26 27 28 Also calculated was the minimal oxygen saturation in relation to respiratory disturbances during the total sleep time (TST) [SaO2 min].
Statistics
The statistical calculations for significant differences between baseline and the treatment modes, with rejection of the null hypothesis at a p < 0.05, were carried out with the analysis of variance with Bonferroni correction. Comparisons between responders and nonresponders to ISAD treatment were effected with the Mann-Whitney test.
| Results |
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The study population was classified into three subgroups by baseline AHI (< 10/h, 10 to < 20/h, and
20/h). In the two more seriously affected groups, AHI and snoring improved significantly after the first night and after 6 weeks with CPAP. In patients with AHI < 10/h, the reduction in respiratory disturbances did not reach the level of significance. There were no significant differences in AHI between baseline and treatment with the ISAD in either of the subgroups (Fig 2
). However, with the ISAD, snoring significantly improved in the two more seriously affected groups in the first night: the subgroup with AHI of 10 to < 20/h snoring baseline, 44.4 ± 13.8 epochs per hour; first night, 26.4 ± 8.2 epochs per hour [p < 0.01]; 6 weeks, 33.8 ± 12.8 epochs per hour (not significant [NS]); and the subgroup with AHI
20/h snoring baseline, 67.1 ± 26.5 epochs per hour; first night, 28.1 ± 2.7 epochs per hour (p < 0.01); 6 weeks, 41.7 ± 13.5 epochs per hour (NS).
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30.5). The AHI showed a tendency to improve in the subgroup with BMI < 27 with both modalities, and significant improvements were seen in the other groups receiving CPAP. Moreover, the ISAD brought about a significant reduction in AHI in patients with a BMI
30.5 both on the first night and after 6 weeks of treatment (Fig 3
).
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Patient self-assessment revealed no significant differences between the two modalities in terms of improvement in daytime sleepiness, snoring, and concentration. The patients identified the ISAD as being easier to use (score of 1 to 6: ISAD, 1.8 ± 1.1; CPAP, 3.1 ± 1.5 [p < 0.05]).
In the questionnaire, the patients reported greater compliance for the ISAD as compared with CPAP. This applied both to the number of nights during which treatment was applied, and also to the hours of use per night (at > 8 h/d: CPAP, 9%; ISAD, 33% [NS]; at 6 to 7 h/d: CPAP, 27%; ISAD, 53% [NS]; at 4 to 5 h/d: CPAP, 64%; ISAD, 7% [p < 0.01]; and at 2 to 3 h/d: CPAP, 0%; IST, 7% [NS]). All patients used both devices on at least 5 nights per week (7 days: CPAP, 54%; ISAD, 62%; and 5 to 6 days: CPAP, 46%; ISAD, 38% [NS]).
With CPAP treatment, eight patients noted a sensation of pressure on the face (with the ISAD, two patients [p < 0.05]). With the ISAD, two patients noted a feeling of pressure in the mouth (with CPAP, 0 patients [NS]). With the ISAD, eight patients complained of early morning, nonpersisting discomfort in the mouth and temporomandibular joint (with CPAP, 0 patients [p < 0.01]). With regard to other side effects, no relevant differences were found. There were no significant differences between the genders in terms of polysomnographic or compliance parameters.
| Discussion |
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30/h), which was confirmed by two diagnostic polysomnographies. This was done both to exclude patients with severe OSAS erroneously diagnosed as mild on the first night in the sleep laboratory due to intraindividual variability, and also to ensure, on the basis of the symptoms and AHI, that the patients investigated really did have OSAS. The ISAD reduced snoring at both measuring time points (first night and 6 weeks) but significantly improved the AHI only in the early phase of treatment. In contrast, CPAP normalized AHI, snoring, and arousals throughout the entire treatment period. The remaining number of microphone signals was similar to those of previous studies using the same definition, and may at least partially be artifacts or nonobstructive snores.26 27 28
This superiority of CPAP may be due to the fact that the ISAD might not have resulted in an enlargement of the upper airways in all patients. Thus, for example, Rodenstein et al30 showed that in patients with OSAS, the long axis of the pharyngeal cross-section may lie in the sagittal plane rather than in the coronary plane. As a result, forward protrusion of the mandible may even diminish the size of the retroglossal space.
Of particular interest would appear to be the fact that the more pronounced effect of the ISAD found initially (first night) subsequently diminished again (6 weeks). Peter et al31 failed to demonstrate an improvement of the success rate of the uvulopalatopharyngoplasty by localizing the site of the stenosis using endoscopy. This was discussed based on the findings that the site of the collapse changes after uvulopalatopharyngoplasty, but an obstruction persists.31 Therefore, our results may also be due to a shift in the location of the obstruction of the upper airways during the course of treatment. In contrast, the effect of CPAP therapy is not influenced by the plane of the long axis of the pharyngeal space, or any shift in the location of the functional narrowing.
Although CPAP therapy is generally more advantageous, adequate treatment (AHI < 10/h) persisting over the longer term was nevertheless also observed in 30% of the patients treated with the ISAD. Responders to treatment with the ISAD were significantly younger than nonresponders. While the mean age of our own patients was 56.5 ± 10.2 years, the patients investigated by Ferguson et al20 had a mean age of 44.0 ± 10.6 years. This might be the explanation for the different percentage of responders found in the two studies. When the group of 20 patients was classified according to BMI, those with the highest BMI showed a significant improvement in AHI with the ISAD (Fig 3) . There were no other differences in the anthropometric or polysomnographic findings between these groups. However, as we did not record body position, the question whether posture might have influenced these results must for the time being remain unanswered.
Another limitation of our study has to be discussed. It is possible that the number of responders might be increased by adjusting the ISAD more specifically. The initial adjustment of the ISAD to 66% of the maximum protrusion was not changed during the treatment period so as to allow the patients to adapt to this form of therapy.
With regard to side effects, mask-related discomfort on the face was frequently observed with CPAP, and morning stiffness in the temporomandibular joint with the ISAD. Evidence of damage in the region of the jaws has not so far been reported,32 although recently published data33 suggest that the use of MADs over 6 to 30 months can cause dental and skeletal changes. The higher percentage of use of the ISAD vs CPAP is in agreement with the results reported by Ferguson et al.20 Moreover, the patients indicated that they found the ISAD easier to use. This might well be the reason why patients applied the ISAD on more days than CPAP. The greater utilization of the ISAD per day might be due to the fact that after waking in the morning, patients no longer reapplied CPAP. The compliance data are largely in accord with the results reported by Weaver et al,34 who found consistent CPAP use (7 d/wk) in 53% of the patients. However, in that study, intermittent users objectively applied their devices between 2% and 79% of the days, whereas all our patients claimed to use CPAP on at least 5 nights per week. This difference may be due to unreliable self-assessment, in particular by irregular users.
On the basis of the results of effectiveness and compliance taken together, the ISAD cannot be recommended for general use in patients with mild-to-moderate OSAS. An advantage of this modality is its greater acceptance. However, especially the most seriously affected subgroup of our population (AHI
20/h) failed to show any relevant improvement in AHI. Therefore, also in patients with mild-to- moderate OSAS, CPAP is superior to treatment with MADs. As one third of the patients respond sufficiently to treatment with the ISAD, in patients who refuse CPAP, the use of mandibular advancement should be considered. The true effectiveness of the ISAD, however, must be assessed on the basis of long-term treatment.
| Footnotes |
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Received for publication July 12, 2001. Accepted for publication March 18, 2002.
| References |
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