Breathing disorders during sleep: often trivial, sometimes complex

OSAS is usually well treatable, with CPAP ventilation finding long-term use in about 70% of cases. CPAP, maxillary advancement splints, and bariatric surgery have a beneficial effect on cardiovascular risk.

The symptoms of obstructive sleep apnea syndrome OSAS, nocturnal breathing pauses combined with increased daytime sleepiness, are now known not only to physicians but also to many patients. The effects of not getting restful sleep, such as increased risk of cardiovascular disease and traffic safety, were often addressed. CPAP therapy is quite well accepted, often due to positive experiences of relatives and acquaintances. The mechanistically explainable process of repetitive breathing interruptions and sleep fragmentation is well understood by those affected. However, much remains to be done to address patients with comorbidities and the desire for alternative therapies. This overview now presents mainly new findings of practical relevance from recent years.

Treatment challenges

Depending on patient selection, CPAP is not accepted or tolerated in up to 30% of cases. The most important therapy alternative is the maxillary advancement splints. These are proven to be effective and are covered by the health insurance companies according to the KVG. Often there is also uncertainty as to what should be done when breathing pauses are observed, even seem frightening, but the affected person does not subjectively suffer from them. Should CPAP be used for increased cardiovascular (CV) risk? Additional expertise is also needed for comorbidities such as pulmonary hypertension due to nocturnal hypoxia, heart failure, obesity hypoventilation, perioperative after anesthesia, opiate therapy, neuromuscular disease, central respiratory disorders after stroke, mixed central obstructive or “complex” sleep apnea. Mixed images of sleep onset and sleep maintenance disorders with sleep apnea are also a major challenge.

Diagnose OSAS

As mostly in medicine, the anamnesis is the most important thing. An important instrument remains the Epworth Sleepines Scale questionnaire (Table 1) [1]. At 10 or more points, there is certainly hypersomnia. In a patient population preselected by primary care physicians, outpatient respiratory polygraphy is usually diagnostic. However, it is not recommended to delegate polygraphs to external laboratories without contacting the continuing care physician, to “check off” the medical history with an attached questionnaire, and to send a diagnostic device without patient contact. Such a practice demonstrates considerable lack of understanding of the complexity that seemingly “simple sleep apnea” not infrequently reaches, and denies the treating specialist insight into original data.

Pulse oximetry alone is not recommended. Laboratory polysomnography is considered the gold standard. Complaints such as sleep-fragmenting restless legs, narcolepsy-specific findings, or more complex sleep breathing disorders such as “upper airway resistance” can only be diagnosed in this way [2].

Different symptoms in men and women?

In an internal survey of approximately 50,000 device prescriptions, it was notable that with an OSAS prevalence ratio of 2:1 in men and women, only about 20% of women received a CPAP device, rather than the 33% expected. There was speculation as to whether OSAS symptomatology was more diverse in women and therefore less well recognized. In fact, there are studies on the symptomatology, which in men can be manifested mainly by daytime sleepiness, but in women also by irritability, adynamia, depression, and others. Since the risk of OSAS in postmenopausal women approaches that of men, it is worthwhile to pay special attention to this group of patients and to obtain a more differentiated medical history.

New population-based data from Switzerland

Researchers at the University of Lausanne have built an excellent population-based database. There, a prevalence of moderate to severe sleep apnea with an AHI of >15 was seen in 23.4% of women and in 49.7% of men. The gender ratio of about 2:1 is confirmed again. In subjects with AHI >20, there was a significant association for hypertension (OR 1.6), diabetes (OR 2.0), metabolic syndrome (OR 2.8), and depression (OR 1.9) [3].

Should we screen given the frequency?

To date, there are no recommendations for screening, even in patients at increased cardiovascular risk. However, the question of sleep quality should be asked in the medical history. If there is a history of snoring and pauses in breathing and evidence of daytime sleepiness, further investigations are recommended. The best and very simple clinical score to date (NoSAS) was also recently published by the Lausanne group (Table 2) [4]. Although non-restorative sleep has an unfavorable effect on memory performance, an examination for sleep-breathing disorders is only part of the basic diagnosis of a dementia work-up if further indications of sleep apnea are present.

CPAP and therapy alternatives

CPAP is still used for most patients. The modern devices are barely audible and very reliable. Built-in chips enable programming and differentiated long-term therapy controls. In some cases, therapy monitoring is already supported by telemedicine.

Maxillary advancement splints, of which there are several models, show an excellent therapeutic effect in several very good studies, even in terms of influencing cardiovascular risk [5,6]. In Switzerland, payers cover the cost of materials in accordance with the MiGeL of CHF 500 every three years and dental costs in accordance with the KVG.

Individual solutions such as palatal braces, muscle training, e.g. with wind instruments (didgeridoo), can work well in individual cases, but remain exceptions. Surgical procedures in various levels of the soft tissues of the neck have become less important, except for tonsillectomy and adenotomy. Whether videoendoscopic techniques can improve the prediction of surgical outcomes in the future remains to be seen. Further developments will be followed here with interest. The tongue base pacemaker is based on an intriguing idea, but has not yet been widely used. After bariatric surgery, however, sleep apnea subsides in a majority of patients. Of course, this is also the case if a striking weight reduction succeeds elsewhere.

Positive effect on cardiovascular risk

The repeatedly demonstrated association of OSAS and CV risk suggests that with treatment, CV risk also decreases. Recently, two large studies have been conducted with low- or asymptomatic OSAS patients with preexisting cardiovascular disease. Both papers failed to demonstrate a risk benefit for CPAP therapy [7,8]. However, in a subgroup analysis, a positive effect was found with regard to cardiovascular events and mortality at a duration of application >4 hours.

In addition, several randomized controlled trials show favorable and sustained effects on blood pressure and decrease in recurrence of AF with therapy. Various positive observational studies on CPAP also show that treatment of OSAS protects against CV complications. We consider that in completely asymptomatic people with incidental findings of sleep apnea (e.g., people during anesthesia induction), no therapy is recommended. However, in cases of increased CV risk and already mild symptoms, the indication for therapy is generous.

Minimize risks of right heart strain

Repetitive apneas and mild oxygen desaturations do not usually lead to pulmonary hypertension (PH). However, comorbidities such as COPD or obesity are common, so that, depending on patient selection, about 50% of all sleep apnea patients have at least mild PH. Therapeutic studies are few, usually trying to minimize the risks of right heart strain, by best correcting sleep breathing disturbance and avoiding hypoxemia at night, occasionally with oxygen supplementation. Therapeutic effects are particularly impressive in obesity hypoventilation, where PH can be normalized and right heart strain can be recompensated [9]. Partial inpatient titrations under nocturnal_CO2 and oxygen monitoring are usually necessary.

CPAP for heart failure

CPAP may be prescribed in principle, but because of the obstruction of venous return by CPAP, high therapy pressures may be contraindicated. Patients with EF below 40% and Cheyne-Stokes respiration have previously used automatic servo-ventilation (ASV) devices, which have reliably resolved the respiratory irregularity. Unfortunately, a recent randomized trial found that this mode of ventilation resulted in increased mortality. Therefore, ASV is contraindicated for this indication until further notice [9].

Roadworthiness and OSAS

Patients with documented effective CPAP therapy without residual daytime sleepiness are generally fit to drive. If there is any doubt, a multiple wake lead test (MWT) may be ordered as an objective examination. Here, the explorand must try to stay awake in a dark room without distraction for 4× 40 minutes throughout the day. Drivers of private vehicles under 3.5 tons should be in the MWT in all passes min. Stay awake for 20 minutes, much stricter limits are required for professional drivers. Guidelines from Swiss sleep and traffic physicians  are expected this year.

Take-Home Messages

• The diagnosis of OSAS is made based on history and respiratory polygraphy or polysomnography.
• Increased daytime sleepiness or drowsiness due to sleep fragmentation is the main reason for treatment.
• OSAS is usually well treatable, with CPAP ventilation finding long-term use in about 70% of cases. Alternatives are mandibular advancement splints and individual solutions.
• CPAP, maxillary advancement splints, and bariatric surgery have favorable influences on cardiovascular risk, but success data for “hard CV endpoints” are difficult to obtain.
• If heart failure or pulmonary hypertension is present, caution is advised and therapy under differential control is indicated.

Literature:

1. Johns MW: A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep 1991; 14: 540-5.
2. Thurnheer R, et al: Respiratory polygraphy in sleep apnea diagnosis. Report of the Swiss respiratory polygraphy registry and systematic review of the literature. Swiss medical weekly 2007; 137: 97-102.
3. Haba-Rubio J, et al: Sleep characteristics and cognitive impairment in the general population: The HypnoLaus study. Neurology 2017; 88: 463-9.
4. Marti-Soler H, et al: The NoSAS score for screening of sleep-disordered breathing: a derivation and validation study. The lancet Respiratory medicine 2016; 4: 742-8.
5. Bloch KE, et al: A randomized, controlled crossover trial of two oral appliances for sleep apnea treatment. American journal of respiratory and critical care medicine 2000; 162: 246-51.
6. Bratton DJ, et al: CPAP vs Mandibular Advancement Devices and Blood Pressure in Patients With Obstructive Sleep Apnea: A Systematic Review and Meta-analysis. JAMA: the journal of the American Medical Association 2015; 314: 2280-93.
7. McEvoy RD, et al: CPAP for Prevention of Cardiovascular Events in Obstructive Sleep Apnea. The New England journal of medicine 2016; 375: 919-31.
8. Peker Y, et al: Effect of Positive Airway Pressure on Cardiovascular Outcomes in Coronary Artery Disease Patients with Nonsleepy Obstructive Sleep Apnea. The RICCADSA Randomized Controlled Trial. American journal of respiratory and critical care medicine 2016; 194: 613-20.
9. Thurnheer R, et al: Precapillary Pulmonary Hypertension and Sleep-Disordered Breathing: Is There a Link? Respiration; international review of thoracic diseases 2017; 93: 65-77.
10. Cowie MR, et al: Adaptive servo-ventilation for central sleep apnea in systolic heart failure. The New England journal of medicine 2015; 373: 1095-105.

HAUSARZT PRAXIS 2017; 12(4): 34-38