Analysis of the myoelectric characteristics of genioglossus in REM sleep and its improvement by CPAP treatment in OSA patients

A Novel Design of an Oral Appliance for Monitoring Electromyograms of the Genioglossus Muscle in Obstructive Sleep Apnea Syndrome

Obstructive sleep apnea (OSA) is a prevalent source of sleep-disordered breathing. OSA is most commonly associated with dysfunctions in the genioglossus (GG) muscle. In this study, we present the first version of a medical device that produces an electromyogram (EMG) of the GG. The prototype is composed of a (custom-made) 3D-printed mouthpiece. Impressions were taken for the lower arch and scanned with a lab scanner to be converted into digital impressions. ExoCad software was used to design the appliance. Fusion 360 software was then used to modify the design and create tubes to house the electrodes in a bilateral configuration to secure excellent and continuous contact with the GG muscle. Silver-silver chloride electrodes were incorporated within the appliance through the created tubes to produce a muscle EMG. In this preliminary prototype, an EMG amplifier was placed outside the mouth, and isolated electric wires were connected to the amplifier input. To test the design, we ran experiments to acquire EMG signals from a group of OSA patients and a control group in wakefulness. The GG EMGs were acquired from the participants for 60 s in a resting state whereby they rested their tongues without performing any movement. Then, the subjects pushed their tongues against the fontal teeth with steady force while keeping the mouth closed (active state). Several features were extracted from the acquired EMGs, and statistical tests were applied to evaluate the significant differences in these features between the two groups. The results showed that the mean power and standard deviation were higher in the control group than in the OSA group (p < 0.01). Regarding the wavelength during the active state, the control group had a significantly longer wavelength than the OSA group (p < 0.01). Meanwhile, the mean frequency was higher in the OSA group (p < 0.01) at rest. These findings support research that showed that impairment in GG activity continues in the daytime and does not only occur during sleep. Future research should focus on developing the device to be more user-friendly and easily used at home during wakefulness and sleep.

Association between overnight repetitive respiratory events and the accumulation of genioglossus fatigue in male patients with severe obstructive sleep apnea

PURPOSE

To evaluate the correlation between median frequency (MF) as a measure of genioglossus (GG) fatigue and overnight repetitive respiratory events in male patients with severe obstructive sleep apnea (OSA).

METHODS

GG electromyography (EMG) data were collected synchronously with polysomnography (PSG). Overnight respiratory events were divided based on whether they occurred during the first or second halves of the total number of overnight respiratory events, and differences in MF in the respiratory phase were compared in the same segments. Events were then sampled in pairs to compare MF. The correlation between MF and the order of respiratory events, as well as interindividual differences, were analyzed.

RESULTS

Twenty-two male patients were enrolled in this study and 2210 respiratory events were recorded. Before and during respiratory events, MF decreased significantly in the second half, especially during the inspiratory phase (segments 1-4: P = 0.014, P < 0.001, P < 0.001, P < 0.001, respectively). This trend was observed in non-rapid eye movement sleep and lateral position, but not in rapid eye movement sleep or the supine position, and remained after pairing for duration, stage, and position. MF correlated negatively with the order of respiratory events during the inspiratory phase. The trend of decrease in MF only existed in patients with apnea-hypopnea index > 30 events/h.

CONCLUSION

Overnight repetitive respiratory events were associated with increased GG fatigue, influenced by sleep stage and body position in male patients with severe OSA. GG fatigue depends on the order and frequency of respiratory events.

A Novel Method to Classify the Responses of Genioglossus to Negative Pressure in OSA Patients

OBJECTIVE

This study aims to develop a novel method to classify different genioglossus (GG) responses to upper airway (UA) negative pressure in obstructive sleep apnea (OSA) patients.

STUDY DESIGN

A single-center, prospective, cohort study.

SETTING

Sleep Medical Center.

METHODS

Patients with OSA underwent drug-induced sleep endoscopy with synchronous genioglossus electromyography (ggEMG) and UA pressure monitoring. In spontaneous obstructive apnea events, the value of epiglottis negative pressure at the end of inspiration (Pepi ) and corresponding peak phasic ggEMG were recorded as pairing data for linear regression analysis to classify GG response modes: peak phasic ggEMG-Pepi linear mode (P < .05) were classified as group 1; others (P ≥ .05) were classified as group 2. Using nasopharyngeal tube (NPT) to reopen the palatopharyngeal cavity for comparing the improvement between the OSA patients with different GG response modes.

RESULTS

Sixty subjects were analyzed for GG response modes: 22 patients were in group 1 (r2  = 0.233-0.867), and 38 patients were in group 2. The proportion of partial (63.16% vs 59.09%) or complete (36.84% vs 22.73%) collapse rate of the tongue base in group 2 was significantly higher (χ2  = 7.823, P = .020). The improvement of the apnea-hypopnea index after NPT placement in group 2 was significantly lower than in group 1 (59.09% vs 31.58%, χ2  = 4.339, P = .037).

CONCLUSION

This novel method is advantageous for distinguishing OSA patients with different GG response abilities to UA negative pressure, whose GG responses conforming to peak phasic ggEMG-Pepi linear mode might be more suitable for palatopharyngeal surgery.

Effects of demographic and sleep-related factors on snoring sound parameters

OBJECTIVE

To investigate the effect of frequently reported between-individual (viz., age, gender, body mass index [BMI], and apnea-hypopnea index [AHI]) and within-individual (viz., sleep stage and sleep position) snoring sound-related factors on snoring sound parameters in temporal, intensity, and frequency domains.

METHODS

This study included 83 adult snorers (mean ± SD age: 42.2 ± 11.3 yrs; male gender: 59%) who underwent an overnight polysomnography (PSG) and simultaneous sound recording, from which a total of 131,745 snoring events were extracted and analyzed. Data on both between-individual and within-individual factors were extracted from the participants' PSG reports.

RESULTS

Gender did not have any significant effect on snoring sound parameters. The fundamental frequency (FF; coefficient = -0.31; P = 0.02) and dominant frequency (DF; coefficient = -12.43; P < 0.01) of snoring sounds decreased with the increase of age, and the second formant increased (coefficient = 22.91; P = 0.02) with the increase of BMI. Severe obstructive sleep apnea (OSA; AHI ≥30 events/hour), non-rapid eye movement sleep stage 3 (N3), and supine position were all associated with more, longer, and louder snoring events (P < 0.05). Supine position was associated with higher FF and DF, and lateral decubitus positions were associated with higher formants.

CONCLUSIONS

Within the limitations of the current patient profile and included factors, AHI was found to have greater effects on snoring sound parameters than the other between-individual factors. The included within-individual factors were found to have greater effects on snoring sound parameters than the between-individual factors under study.

Phenotyping REM OSA by means of peripheral arterial tone-based home sleep apnea testing and polysomnography: A critical assessment of the sensitivity and specificity of both methods

The clinical relevance of rapid eye movement sleep-related obstructive sleep apnea (REM OSA) is supported by its associated adverse health outcomes and impact on optimal treatment strategies. To date, no assessment of REM OSA phenotyping performance has been conducted for any type of sleep testing technology. The objective of this study was to assess this for polysomnography and peripheral arterial tone-based home sleep apnea testing (PAT HSAT). In a dataset comprising 261 participants, the sensitivity and specificity of the agreement on REM OSA phenotyping was assessed for two independent scorings of polysomnography and a synchronously administered PAT HSAT. The sensitivity and specificity of REM OSA phenotyping were 0.87 and 0.89, respectively, for the polysomnography inter-scorer comparison, and 0.68 and 0.97 for the PAT HSAT on a single-night basis, using the conventional minimum required rapid eye movement sleep time of 30 min. Polysomnography-based REM OSA phenotyping was found to be sensitive and specific even for a single-night testing protocol. Peripheral arterial tone-based REM OSA phenotyping showed a lower sensitivity but a slightly higher specificity compared to polysomnography. In order to increase performance and conclusiveness of peripheral arterial tone-based REM OSA phenotyping, a multi-night protocol of 2-5 nights could be considered. Finally, the minimum required rapid eye movement sleep time could be lowered from the conventional 30 min to 15 min without significantly lowering REM OSA phenotyping sensitivity and specificity, while increasing the level of phenotyping conclusiveness.

Obstructive sleep apnea and respiratory center regulation abnormality

PURPOSE

Obstructive sleep apnea (OSA) is a complex disease in which phenotypic analysis and understanding pathological mechanisms facilitate personalized treatment and outcomes. However, the pathophysiology responsible for this robust observation is incompletely understood. The objective of the present work was to review how respiratory center regulation varies during sleep and wakeness in patients with OSA.

DATA SOURCES

We searched for relevant articles up to December 31, 2019 in PubMed database.

METHODS

This review examines the current literature on the characteristics of respiratory center regulation during wakefulness and sleep in OSA, detection method, and phenotypic treatment for respiratory center regulation.

RESULTS

Mechanisms for ventilatory control system instability leading to OSA include different sleep stages in chemoresponsiveness to hypoxia and hypercapnia and different chemosensitivity at different time. One can potentially stabilize the breathing center in sleep-related breathing disorders by identifying one or more of these pathophysiological mechanisms.

CONCLUSIONS

Advancing mechanism research in OSA will guide symptom research and provide alternate and novel opportunities for effective treatment for patients with OSA.