The goal of this prospective study is to gain insight into the endophenotypic variation in OSA, with a focus on the underlying pathophysiological traits and the cardiovascular alterations associated with the condition. To capture the variability in OSA endophenotypes, novel metrics that extend beyond the AHI will be considered, with particular attention to the sleep-apnea-specific hypoxic burden, the sleep-apnea-specific heart rate response, and pulse wave amplitude drops (PWADs). Since the impact of treatment on cardiovascular parameters remains an important point of interest, the effects of different treatment modalities on cardiovascular changes will be investigated, including continuous positive airway pressure (CPAP), mandibular advancement devices (MADs), and hypoglossal nerve stimulation.
Study Type
OBSERVATIONAL
Enrollment
270
CPAP remains the most commonly used treatment modality and is considered as the gold standard for patients with OSA because of its high efficacy and noninvasive nature. CPAP therapy is indicated for patients with moderate to severe OSA (AHI ≥ 15/h) or for those with a lower AHI with symptoms of excessive daytime sleepiness. It is effective in reducing nocturnal obstructive events by delivering continuous positive airway pressure, which functions as a pneumatic splint to keep the upper airway open and prevent pharyngeal collapse during sleep \[16\]. CPAP therapy generally improves sleep parameters, enhances blood oxygen saturation and causes disappearing of OSA-related symptoms. Although CPAP is really effective in treating OSA, many patients struggle with intolerance and long-term adherence remains a significant challenge.
Mandibular advancement device (MAD) has become a widely recognized non-invasive treatment alternative for patients who cannot tolerate CPAP. It is primarily indicated for mild to moderate OSA and lately also for severe OSA patients. These MADs are worn intraorally during the night and attach to both upper and lower dental arches, protrude the lower jaw to widen and reopen the upper airway.
Hypoglossal nerve stimulation (HNS) is a novel and unique therapeutic option for patients with moderate-to-severe OSA who cannot be treated effectively with CPAP or MAD. In contrast to traditional reconstructive procedures for OSA, which focus only on anatomical adjustments, HNS integrates a surgical implantation process with an adjustable medical device to open the upper airway through neuromodulation of the hypoglossal nerve.
Sleep apnea-specific hypoxic burden (SASHB)
This novel metric is calculated by determining the total area under the respiratory event-related desaturation curve, which can be obtained from a polysomnography (PSG). It has been shown to be a good predictor of cardiovascular disease mortality, but has not yet been established in daily practice.
Time frame: 1 year
Cardiovascular outcome: interventricular septum thickness
Interventricular septal thickness will be assessed via 2D-guided M-mode echocardiographic measurements in the parasternal long-axis view.
Time frame: 1 year
Cardiovascular outcome: left ventricular ejection fraction
Left ventricular ejection fraction will be assessed via 2D-guided M-mode echocardiographic measurements in the parasternal long-axis view.
Time frame: 1 year
Cardiovascular outcome: heart rate variability
Heart rate variability will be calculated from ECG-derived RR intervals obtained during the sleep study.
Time frame: 1 year
OSA efficacy: delta apnea-hypopnea index (AHI)
The apnea-hypopnea Index (AHI), defined as the number of apneas (cessations in breathing) and hypopneas (reductions in airflow) per hour of sleep measured during a polysomnography, will be assessed. OSA is diagnosed when the AHI is at least 5/h. The AHI classifies OSA as mild with AHI ranging from 5 to 14.9 events per hour, moderate with AHI ranging from 15 to 29.9 events per hour and severe when 30 or higher events per hour.
Time frame: 1 year
Heart rate response to a respiratory event (ΔHR)
ΔHR is defined as the difference between the maximum pulse rate after airway opening, i.e. during a subject-specific search window, and an event-related minimum pulse rate, i.e. minimum pulse rate during respiratory events. ΔHR will be calculated from a photoplethysmography (PPG), a signal derived from a finger pulse oximeter, which is part of the standard clinical PSG set-up.
Time frame: 1 year
Pulse wave amplitude drops (PWADs)
PWADs can be calculated from photoplethysmography (PPG), a signal derived from a finger pulse oximeter, which is part of the standard clinical PSG set-up.
Time frame: 1 year
Cardiovascular outcome: 24-hour ambulatory blood pressure
24-hour ambulatory blood pressure will be measured using ambulatory blood pressure monitoring (ABPM).
Time frame: 1 year
Cardiovascular outcome: systolic and diastolic function
Left ventricular systolic and diastolic function will be evaluated using 2D echocardiography. Systolic function will be quantified by left ventricular ejection fraction calculated using the Simpson biplane method. Diastolic function will be assessed using pulsed wave tissue Doppler imaging at the septal and lateral mitral annulus, mitral inflow velocities (E/A ratio), the E/e' ratio and left atrial volume index.
Time frame: 1 year
Therapy adherence defined by the amount of hours of therapy usage per night and the number of nights per week of use
Average hours of therapy use per night and the number of nights per week can be retrieved from data stored in the device.
Time frame: 1 year
Degree of snoring measured by Visual Analogue Scale (VAS)
Visual analogue scale for snoring, from 0 to 10: 0 represents no snoring, 1-3 represents minimally annoying, 4-6 represents moderately annoying, 7-9 represents annoying, and 10 represents extremely annoying.
Time frame: 1 year
Daytime sleepiness measured by the Epworth Sleepiness Scale (ESS) questionnaire
Daytime sleepiness measured using the Epworth sleepiness scale (ESS), which is a self-administered questionnaire that assesses the likelihood of falling asleep in various settings and situations in daily life.The questionnaire consists of eight items scored from 0 to 3, resulting in a total score ranging from 0 to 24. The lowest score (zero) suggests that the described incident is absent and the highest score (three) suggests the presence of this event.
Time frame: 1 year
Fatigue measured by the Checklist Individual Strength (CIS) questionnaire
Fatigue was assessed using the checklist individual strength, a 20-item questionnaire with each item scored on a 7-point Likert scale, resulting in total scores ranging from 20 to 140. Higher scores indicate greater fatigue severity.
Time frame: 1 year
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