The potential of a remotely controlled mandibular positioner (RCMP) during sleep studies in individual patients suffering from obstructive sleep apnea (OSA) for the determination of the effective target protrusive position (ETPP) of the mandible has been demonstrated. The research goal of this study was to assess the feasibility of the application of RCMP during drug-induced sleep endoscopy (DISE) for the determination of ETPP.
Ten patients in whom OSA was diagnosed (50% male; age 54 ± 9.5 years; body mass index 26.9 ± 2.1 kg/m2; apnea-hypopnea index 28.4 ± 13.2 events/h) were enrolled prospectively. Dental RCMP trays were fitted during wakefulness. Maximal protrusion and edge-to-edge positions were measured. Upper airway collapsibility was scored during DISE, including full-range mandibular RCMP titration within 45 minutes. ETPP was defined as the mandibular threshold protrusion yielding a stable upper airway in the absence of snoring, oxygen desaturation and apneas.
RCMP trays were retentive and no adverse reactions occurred. RCMP was fitted intraorally prior to sedation with maxillary and mandibular trays in edge-to-edge position. Upon sedation, progressive protrusion was performed followed by reversed titration until ETPP was noted. In one patient ETPP was not within the mandibular range of motion. In one patient RCMP needed to be removed because of clenching.
The results of this study illustrate that it is feasible to use RCMP during DISE and to determine ETPP within 45 minutes. Comparative research with polysomnography would be useful to further validate the therapy outcome upon use of RCMP during DISE.
Kastoer C, Dieltjens M, Op de Beeck S, Braem MJ, Van de Heyning PH, Vanderveken OM. Remotely controlled mandibular positioning during drug-induced sleep endoscopy toward mandibular advancement device therapy: feasibility and protocol. J Clin Sleep Med. 2018;14(8):1409–1413.
Mandibular advancement devices (MAD) used in the treatment of obstructive sleep apnea (OSA) rely on mandibular protrusion promoting airway widening, increase in pharyngeal dilator muscle activity, decreased upper airway resistance, and decreased pharyngeal collapsibility.1,2 MAD provide a noninvasive alternative to continuous positive airway pressure (CPAP) therapy.
Custom titratable MAD are recommended for individual gradual mandibular protrusion after fitting, called titration, in search of optimal mandibular protrusion within a patient's physical limits.1,3 Titration is guided by changes in subjective symptoms and/or objective measurements and is often a time-consuming trial-and-error procedure.4 Larger advancement is not always associated with corresponding reduction in apnea-hypopnea index (AHI) whereas smaller vertical opening is associated with decrease in pharyngeal collapsibility.2,5 MAD therapy improves upper-airway collapsibility with treatment response depending on the phenotype of the individual patients: upper-airway collapsibility as well as loop gain being the relevant predictors.6 Consequently, the therapy outcome of MAD treatment varies largely between patients.
It has been illustrated that the remotely controlled mandibular positioner (RCMP) can be implemented during overnight sleep studies to determine the optimal mandibular protrusion for MAD treatment in individual patients, referred to as the effective target protrusive position (ETPP).4,7 Literature has shown a greater reduction in AHI with custom titratable MAD after RCMP-titration as compared to conventional titration methods.7 Nothing is known yet on the use of RCMP during drug-induced sleep.
The current study, therefore, looks at the feasibility of using RCMP during drug-induced sleep endoscopy (DISE) for instant determination of ETPP.
Study Setting and Patient Characteristics
Ten patients with OSA (50% male; age 54 ± 9.5 years; body mass index 26.9 ± 2.1 kg/m2; AHI 28.4 ± 13.2 events/h) were enrolled prospectively. All patients were clinically examined during wakefulness by experienced ENT surgeons and dental sleep professionals. Subsequently, impression trays of a commercially available RCMP (MATRx, Zephyr Sleep Technologies Inc., Calgary, Canada) were filled with a high-viscosity bite registration material (Blu-Mousse, Parkell Inc., Edgewood, New York, United States), mimicking MAD and connected to RCMP-controlled man-operated software. The Medical Ethics Committee of Antwerp University Hospital/University of Antwerp approved the study protocol.
Upon connection of the RCMP to a designated laptop, the actual versus the software-guided protrusions were calibrated using the RCMP ruler (Figure 1) and proprietary developed software, to rule out day-to-day variation caused by environmental factors such as room temperature or humidity. This procedure ensured the mandibular movement could be read directly from the ruler (Figure 1). Patients were positioned supine in a hospital bed in an operating theater. RCMP trays were fitted in the awake patient in the edge-to-edge position to avoid excessive muscle tension. During DISE, electrocardiography, blood pressure, and oxygen saturation were monitored continuously. First, a flexible fiberoptic nasendoscope (Type ENF-GP, Olympus Europe GmbH, Hamburg, Germany) was introduced by one experienced ENT surgeon in the awake patient to evaluate the awake upper airway state. DISE was subsequently initiated in a semi-dark and silent environment. Sedation was induced by intravenous administration of midazolam (bolus injection of 1.0 to 2.0 mg) and propofol through a target-controlled infusion system (2.0 to 3.0 μg/mL). The transition to unconsciousness similar to stage N2 sleep was the focus and examined by ensuring absence of patients' eyelash reflex after stimulation by means of a gentle brush. Findings were noted using a uniform upper airway scoring system evaluating level of snoring, presence of apneas, degree of oxygen saturation, degree and configuration of obstruction(s) at the level of palate, oropharynx, tongue base, hypopharynx, and epiglottis.8 When target sedation was reached, RCMP was initiated software-wise while protruding the mandible in increments of 1 mm toward the point of maximal comfortable protrusion as determined awake. With a stable upper airway in the absence of snoring, oxygen desaturation and apneas were then evaluated, the mandible was remotely retruded 2 mm, referred to by the authors as “reversed titration.” If the upper airway was still stable, reversed titration then continued. If the upper airway was collapsed, snoring, desaturations or apneas occurred, and RCMP protruded the mandible 1 mm. After every protrusive or retrusive movement the RCMP protrusion was checked on the RCMP ruler (Figure 1) versus the software protrusion, ensuring correct position of the mandible.8 This approach was repeated until ETPP could be determined, defined as the minimal mandibular threshold position of a stable upper airway in the absence of snoring, oxygen desaturation, and apneas.
RCMP with incorporated ruler.
Commercially available RCMP device (MATRx, Zephyr Sleep Technologies Inc., Calgary, Canada). A ruler is incorporated in the RCMP design for calibration and evaluation of mandibular position. RCMP = remotely controlled mandibular positioner.
After ETPP determination the trays with RCMP were removed, allowing scoring of the upper airway during “baseline” state, during head rotation observing nonsupine-dependent OSA or snoring,9 and during chin lift.
All DISE procedures were instantly processed using a medical video platform (NeBULA, eSATURNUS nv, Leuven, Belgium) with all stages individually marked (awake, RCMP edge-to-edge tray position, RCMP protrusion, RCMP retrusion, baseline, head rotation [non-supine], chin-lift).
DISE with RCMP was performed in 10 patients. In 8 of 10 patients ETPP could be determined successfully while in one patient snoring, apneas and oxygen desaturations did not resolve within the patients' range of motion from maximal retrusive position to maximal protrusive position of the mandible, and in another patient RCMP needed to be removed because of clenching.
Table 1 depicts mean ETPP at 67% of the total mandibular range of motion, showing a range from 37% to 88% in individual patients.
Patient characteristics and ETPP determined during DISE.
Patient characteristics and ETPP determined during DISE.
Findings and Earlier Studies
The current study emphasizes the feasibility to perform RCMP-titration during DISE. Patients tolerated the RCMP trays well and no loss of retention occurred during the procedure.
Maximal retrusion, maximal protrusion, ETPP, and range of motion are shown in Table 1. The mean ETPP trajectory from maximal retrusive position of the mandible being 7.3 mm is of little clinical value as ETPP varies largely between patients: at this position 3 patients would have insufficient resolution of snoring, apneas and oxygen desaturations, whereas in 4 patients less protrusion of the mandible turned out to be more favorable.
These findings stress the importance and relevance of an individualized patient-specific, prospective and well-controlled titration of the therapeutic mandibular position when treating OSA with MAD, whereas currently determination of such target mandibular protrusion is rather empirical in clinical practice.10 The potential of RCMP therefore lies in selecting patients for MAD treatment by prospectively determining ETPP (eg, during overnight sleep studies).7,11 Computer-controlled autotitrating mandibular positioners in an unattended setting are also described.12
The ability to determine ETPP in patients during DISE before MAD treatment starts, is thus of great added value to the field, as titration sleep studies and/or trial-and-error MAD titration could be bypassed. However, its clinical and predictive power has yet to be confirmed by performing sleep studies with MAD in the determined ETPP, investigating therapeutic success. In addition, crossover trials of DISE with RCMP versus RCMP during sleep studies is mandatory to clinically validate the use of RCMP during DISE.
Earlier research demonstrated the success of DISE-assisted CPAP titration, to determine the optimal individual air-pressure settings to prevent upper airway collapse, as a cheaper and less time consuming alternative to conventional CPAP titration during full-night sleep studies.13,14
Limitations and Recommendations
Some limitations of RCMP were encountered especially as to the available mandibular range of motion of 12 mm, because maximal mandibular range of motion in 4 patients exceeded this hardware/software limit (Table 1). Also in RCMP during sleep studies high rates of inconclusive tests (> 20%) occurred, of which 33% were related to this RCMP maximal protrusive limit.7,11
In the current feasibility study only one RCMP investigation was inconclusive because of early removal of RCMP following jaw clenching.
Since the bite registration with the trays was carried out prior to the RCMP with DISE, we observed that the trays could shift up to 1 mm upon refitting and therefore had to be adjusted manually. Another point of attention is bending of the extension with the ruler of the RCMP trays upon further protrusion, requiring control of the actual protrusion versus the software-determined one after each protrusion step, including manual adjustment if necessary.
Slow continuous protrusion is not possible: the RCMP immediately moves stepwise to the desired next protrusive position. During sedation, protruding in increments as low as 1 mm caused the mouth floor muscles to contract. Retrusion did not cause such contractions. Slower protrusion in increments of 0.2 mm, as done in recent RCMP sleep study trials in reaction to respiratory events,15 would be possible but will require more time. It is suggested to set the maximal registration time of DISE with RCMP at 45 minutes to avoid ergonomic discomfort of the examiner, hypersalivation of the patient because of the trays, patient movements, arousals, and submental tension possibly because of genioglossus muscle traction.
When the RCMP trays were initially inserted in the awake patient just prior to sedation and in the so-called edge-to-edge position, the patients all showed increased reactivity provoking jaw movements and a tendency to counteract the RCMP procedure. As soon as such behavior was noted, the RCMP was instructed to retrude as much as possible thereby alleviating this adverse behavior, and the tests were then resumed with incremental protrusion as discussed before.
The results of the current feasibility study illustrate the potential of the application of RCMP during DISE and to prospectively determine ETPP, all within 45 minutes.
Comparative research between DISE and sleep studies, also assessing therapeutic outcome with MAD in the ETPP obtained during DISE with RCMP, are needed to further validate the use of RCMP during DISE.
Work for this study was performed at Antwerp University Hospital. All authors have seen and approved the manuscript. Zephyr Sleep Technologies Inc. provided the remotely controlled mandibular positioner (MATRx) and trays. Dr. M. Dieltjens holds a Postdoctoral fellowship at Research Foundation-Flanders (FWO)-12H4516N (2012-2017). Prof. M.J. Braem is promoter of a research grant from SomnoMed Ltd. at Antwerp University Hospital (2013–2020) and has received research support from ResMed as consultant and speaker. Prof. O.M. Vanderveken holds a Senior Clinical Investigator Fellowship from the Research Foundation-Flanders (FWO)-1833517N (2016-2021). Prof. O.M. Vanderveken is co-promoter of a research grant from SomnoMed Ltd. at Antwerp University Hospital (2013–2020). He has received research support from Inspire Medical Systems, from ReVent and from Nyxoah. Prof. Vanderveken receives research support from Philips Respironics and Nightbalance. Prof. O.M. Vanderveken reports serving on an advisory board for Zephyr Sleep Technologies Inc. and for Galvani Bioelectronics, and, receiving lecture fees from Inspire Medical Systems and SomnoMed Ltd. The other authors report no conflicts of interest.
The Emerging Technologies section focuses on new tools and techniques of potential utility in the diagnosis and management of any and all sleep disorders. The technologies may not yet be marketed, and indeed may only exist in prototype form. Some preliminary evidence of efficacy must be available, which can consist of small pilot studies or even data from animal studies, but definitive evidence of efficacy will not be required, and the submissions will be reviewed according to this standard. The intent is to alert readers of Journal of Clinical Sleep Medicine of promising technology that is in early stages of development. With this information, the reader may wish to (1) contact the author(s) in order to offer assistance in more definitive studies of the technology; (2) use the ideas underlying the technology to develop novel approaches of their own (with due respect for any patent issues); and (3) focus on subsequent publications involving the technology in order to determine when and if it is suitable for application to their own clinical practice. The Journal of Clinical Sleep Medicine and the American Academy of Sleep Medicine expressly do not endorse or represent that any of the technology described in the Emerging Technologies section has proven efficacy or effectiveness in the treatment of human disease, nor that any required regulatory approval has been obtained.
body mass index
continuous positive airway pressure
drug-induced sleep endoscopy
ear nose throat
effective target protrusive position
Epworth Sleepiness Scale
mandibular advancement devices
obstructive sleep apnea
remotely controlled mandibular positioner
visual analogue scale
The authors are grateful to Shouresh Charkhandeh for his technical advice and research assistance.
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