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Obstructive sleep apnea in outpatient care – What to do with?
CRVASA-551; No. of Pages 7 cor et vasa xxx (2017) e1–e7
Available online at www.sciencedirect.com
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Review article
Obstructive sleep apnea in outpatient care – What to do with? Monika Kamasová *, Jan Václavík, Eva Kociánová, Miloš Táborský Department of Internal Medicine I – Cardiology, University Hospital Olomouc and Palacký University Olomouc, Faculty of Medicine, I. P. Pavlova 6, 775 20 Olomouc, Czech Republic
article info
abstract
Article history:
Obstructive sleep apnea is a relatively common sleep disorder, which is on the increase in
Received 24 August 2017
the last decades. It significantly contributes to morbidity and mortality in all countries
Accepted 23 September 2017
worldwide. Obstructive sleep apnea is one of the most common causes of daytime sleepi-
Available online xxx
ness. Typical risk factors for obstructive sleep apnea in the normal adult population are male
Keywords:
of manifest cardiovascular disease, diabetes mellitus, and anomalies in the upper respira-
gender, obesity (preferentially central obesity), and increased neck circumference, presence Obstructive sleep apnea
tory tract. Early diagnosis and treatment improves not only the quality of life, but also
Screening
significantly decreases patient morbidity and mortality. Nowadays screening can be per-
Diagnostics
formed in outpatient settings using simple and readily available devices. Such screening can
Outpatient care
contribute to early diagnosis and treatment of obstructive sleep apnea. © 2017 The Czech Society of Cardiology. Published by Elsevier Sp. z o.o. All rights reserved.
Contents Introduction . . . . . . . . . . . . . . . . Definition and pathophysiology . Prevalence . . . . . . . . . . . . . . . . . . Clinical symptoms . . . . . . . . . . . Diagnosis and therapy . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . Ethical statement . . . . . . . . . . . . Funding body . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . .
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* Corresponding author at: Department of Internal Medicine I – Cardiology, University Hospital Olomouc and Palacky University, Faculty of Medicine and Dentistry, I. P. Pavlova 6, 775 20 Olomouc, Czech Republic. E-mail addresses: [email protected] (M. Kamasová), [email protected] (J. Václavík), [email protected] (E. Kociánová), [email protected] (M. Táborský). http://dx.doi.org/10.1016/j.crvasa.2017.09.004 0010-8650/© 2017 The Czech Society of Cardiology. Published by Elsevier Sp. z o.o. All rights reserved.
Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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Introduction Obstructive sleep apnea is a relatively common disease with potential neurocognitive, cardiovascular and metabolic consequences [1]. According to the American Academy of Sleep Medicine (AASM) 2017 guideline, obstructive sleep apnea belongs, together with central sleep apnea and sleep related hypoventilation, to sleep-disordered breathing [2].
Definition and pathophysiology Obstructive sleep apnea is the most common type of the sleepdisordered breathing (SDB) characterized by episodes of upper airway collapse during sleep. These episodes cause cessation or significant reduction of airflow despite of ongoing respiratory efforts. In patients suffering from obstructive sleep apnea, airway dilating muscles can no more resist the negative pressure in airways during inspiration. The muscle tone is reduced during sleep and airways become contracted [3]. These episodes are typically accompanied by repeated oxyhemoglobin desaturation and terminated by short microarousals when the airway patency is restored. Sleep is fragmented and sympathetic nervous system is activated. Airway patency restoration is followed by hypercapnia, hypoxemia and subsequent compensatory hyperventilation. These events lead to fragmented sleep as the patient oscillates between wakefulness and sleep. In severe cases respiratory events can occur more than 100 times per hour; each event typically lasts 20–40 s [4]. Patients suffer from reduced deep NREM 3 and REM sleep [5,6]. In patients with obstructive sleep apnea, anatomic airway constrictions (enlarged tonsils, extended soft palate, and macroglossia) are often found. Obstructive sleep apnea severity is expressed by the apnea– hypopnea index (AHI), which is defined as the number of apnea and hypopnea events per hour of monitored sleep. Apnea is defined by complete obstruction of the upper airways lasting for at least 10 s (i.e. airflow restriction by more than 90% (according to AASM criteria)) (Table 1). Hypopnea is defined as
airflow restriction more than 30% (according to AASM criteria) lasting for more than 10 s. According to AHI, obstructive sleep apnea is categorized as mild (AHI 5–15 episodes/h), moderate (AHI 15–30 episodes/h), and severe (AHI ≥30 episodes/h). The oxygen desaturation index (ODI) is defined as the number of desaturations per 1 h of monitored sleep when oxygen saturation is reduced as compared to the baseline standard level. The respiratory effort related arousal (RERA) can also be used. RERA is defined as an episode characterized by an increased respiratory effort caused by upper airway airflow reduction resolved with arousal and accompanied in most cases with hypoxemia. The respiratory disturbance index (RDI) is the sum of RERA and AHI. According to the third edition of the International Classification of Sleep Disorders (ICSD-3), obstructive sleep apnea (OSA) is defined as polysomnography derived obstructive respiratory disturbance index (RDI) ≥5 events/h associated with typical OSA symptoms, or an obstructive RDI ≥15/h in the absence of clinical OSA symptoms. The American Academy of Sleep Medicine (AASM) defines obstructive sleep apnea as AHI (apnea–hypopnea index – see below) more than 15, or AHI larger than 5 in presence of symptoms [2].
Prevalence Prevalence of obstructive sleep apnea depends on the population studied (see Table 2). It is estimated to be 14% in men and 5% in women (OSA being defined as AHI ≥5 associated with clinical symptoms) (3). In some populations, prevalence of OSA can be higher (e.g. the estimated prevalence in patients undergoing bariatric surgery is 70–80%; prevalence is also higher in stroke patients) [7–9]. Higher prevalence is found in patients with ischemic heart disease [10], heart failure, resistant hypertension [11] (screening to exclude sleep apnea should be performed in all patients with resistant hypertension), in patients suffering from obesity [12], type 2 diabetes mellitus and arrhythmias like atrial fibrillation [13,14]. Studies have revealed that 82% and 93% of women with moderate and severe sleep apnea, respectively, remain undiagnosed [15].
Table 1 – Basic terms and definitions. Definitions Hypopnea Apnea Apnea–hypopnea index (AHI)
Respiratory disturbance index (RDI) Desaturation index (ODI) Respiratory effort related arousal (RERA)
Obstructive sleep apnea syndrome
Airflow restriction more than 30% (according to AASM criteria) lasting for more than 10 s Full airway closure lasting for at least 10 s (i.e. airflow restriction by more than 90% (according to AASM criteria)) Number of apnea and hypopnea events per hour of monitored sleep AHI 5–15 – mild sleep apnea syndrome AHI 15–30 – moderate sleep apnea syndrome AHI >30 – severe sleep apnea syndrome Sum of RERA and AHI Number of desaturations per hour of monitored sleep An episode characterized by an increased respiratory effort caused by upper airway airflow reduction resolved with arousal and accompanied in most cases with hypoxemia At least 5 episodes per 1 h of sleep (apnea or hypopnea) accompanied with some of the following symptoms: (1) excessive daytime sleepiness that cannot be explained by any other reason; (2) two and more of the following symptoms: choking or gasping, repeating arousals, daytime sleepiness, inability to concentrate, unfreshening sleep
Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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Table 2 – Sleep apnea prevalence. Sleep apnea prevalence Atrial fibrillation Myocardial infarction Resistant arterial hypertension Heart failure Obesity Stroke
% 32–49 60–65 64–83 50–68 71–78 50–70
Clinical symptoms The most common clinical symptoms of sleep apnea (see Fig. 4) include excessive daytime sleepiness and frequent daytime dozing off, fatigue, night insomnia, unrefreshing sleep, snoring, gasping during sleep, depressions, headache, decreased work performance, and dry mouth [2]. The main risk factors are obesity, metabolic syndrome, consumption of excessive food at bedtime, consumption of alcohol at bedtime, smoking, use of hypnotics and, in general, of medicines lowering the upper airway muscle tone, male gender, and irregular sleep. Correlation between the sleep apnea severity and higher alcohol consumption [16] and larger neck circumference is known. Although sleep apnea is considered to be a relatively newly described disorder, separate OSA case reports can be found in the 19th century medical journals [17]. Despite high OSA prevalence in the general population, this disease often remains undiagnosed because patients usually consider their symptoms to be normal. Inability to recognize a
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clinically significant obstructive sleep apnea syndrome (OSAS) can affect adversely the health condition, because the disease is related to significant morbidity and mortality. Excessive daytime sleepiness impairs severely the quality of life, cognitive performance, and social interactions [18,19]. Obstructive sleep apnea is related to three-to seven-fold increase of the number of traffic accidents [20]. Obstructive sleep apnea is an independent risk factor for development of cardiovascular disease, especially hypertension, but also ischemic heart disease, heart failure, and stroke [21]. Close relation to diabetes and metabolic syndrome development is also known. Untreated OSAS can bear increased health care cost.
Diagnosis and therapy Diagnosis of obstructive sleep apnea starts in a GP's clinic. Patients often come because their partner cannot sleep due to their snoring [22]. All patients should undergo physical examination and their history should be checked. In the out-patient care questionnaires are used to assess the probability of obstructive sleep apnea syndrome (Epworth Sleepiness Scale – Fig. 1; Berlin Questionnaire – Fig. 2, STOPBANG questionnaire, Sleep Apnea of Sleep Disorder Questionnaire SA-SDQ, and others). The available data show that, for example, the Berlin Questionnaire sensitivity is high; its lower specificity is caused by a high number of false positive results [23,24]. The Berlin Questionnaire is a useful assessment tool for the initial screening of patients with suspect obstructive sleep apnea. The questionnaire consists of three parts – the
Fig. 1 – Epworth Sleepiness Scale. Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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Fig. 2 – Berlin questionnaire.
first one is aimed at snoring, the second one at apnea during sleep and daytime sleepiness, and the third one at hypertension [25]. Score of 8 has been proposed as a cut-off value when patients should be examined for a sleep disorder [26]. According to a study performed by Brazilian physicians, positive correlation of the Berlin Questionnaire and the Epworth Sleepiness Scale has been proven (OSA diagnosis was confirmed in 94.75% of high-risk patients according to the Berlin Questionnaire while in 59.65% of high-risk patients according to the Epworth Sleepiness Scale) [27]. Polysomnography is considered to be the gold standard in the diagnosis of obstructive sleep apnea. It is currently performed by sleep laboratories. In outpatient care, level 4 screening devices can be used (e.g. ApneaLink, Somnocheck, etc.). They usually have one or two recording channels: one channel measures the airflow by a nasal cannula connected to a pressure sensor (providing the apnea–hypopnea index) and an oximeter monitoring blood saturation by oxygen. The above mentioned screening devices have been validated by clinical studies. They are easily available, easy to interpret and provide reliable AHI information as compared to level 1–3 devices [28,29]. Fig. 3 shows an assessment of ApneaLink record.
If the apnea–hypopnea index found out by ApneaLink is more than 15 the patient is sent for further comprehensive examination to a sleep disorder center. The current list of the individual sleep centers is available at www.sleep-society.cz. Polysomnography (or limited polygraphy) is performed there to confirm the diagnosis and the patients are treated, usually by pressure ventilation CPAP/BiPAP. Patients with severe sleep apnea proved by the screening (AHI 30 and up) associated with clinical symptoms evidencing sleep apnea syndrome should be examined in the sleep center preferentially. In patients with AHI 5–15 not associated with clear clinical symptoms of obstructive sleep apnea, the outpatient examination should be repeated and the patients should be then referred, depending on the result of the followup examination, to a sleep laboratory. Change of life style, early diagnosis of comorbidities and their treatment are important in therapy of obstructive sleep apnea. Change of life style includes body weight reduction, reduction of alcohol consumption, cessation of use of medicines (those influencing negatively the upper airway tone) and of smoking, change of sleeping position, etc. Tenpercent body weight reduction is known to reduce AHI by 26%
Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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Fig. 3 – (a) ApneaLink record proving severe sleep apnea. (b) ApneaLink record with physiological finding. The red arrow shows the airflow curve. The green arrow shows blood saturation by oxygen. (c) ApneaLink record with apnea. The red arrow shows airflow cessation and the green arrow the corresponding decrease of saturation.
Fig. 4 – Clinical symptoms of obstructive sleep apnea. *Adjusted according to CPAP guide (https://cpapguide.net/ sleep-apnea-symptoms-need-know/).
[30]. Continuous positive airway pressure (CPAP) is a preferred method of treatment of obstructive sleep apnea. CPAP is a form of non-invasive mechanical ventilation which forms continuous positive pressure in the airways [31]. In some cases, other forms of non-invasive ventilation can be used, e.g. bi-level positive airway pressure (BPAP), adaptive support ventilation
(ASV), etc. Oral appliances causing mandibular protrusion are an alternative to the pressure ventilation. Upper airway surgery can also be performed [32,33]. A recent study investigated whether treatment by continuous positive airway pressure (CPAP) therapy prevents the development of severe cardiovascular events [34]. The study
Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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included 2717 patients (with moderate to severe obstructive apnea and manifest cardiovascular disease) who were randomized either to CPAP or standard therapy (life style measures). The primary endpoint was a composite of death from any cardiovascular cause, myocardial infarction, stroke, hospitalization for unstable angina, heart failure, or transient ischemic attack (TIA). The secondary endpoint was to assess the influence of quality of life, snoring, daytime sleepiness, and the patient mood. The patients were monitored for 3.7 years on average. According to results, CPAP decreased significantly the daytime sleepiness and improved quality of the patients' life; however, no reduction of severe cardiovascular events was observed. The study was limited by the fact that not all patients underwent polysomnography to exclude central sleep apnea. The average nocturnal duration of CPAP use (3.3 h) was relatively short in patients participating in the study [34]. Other randomized studies showed better results in patients treated by CPAP as compared to standard therapy if patients used the therapy for at least 4 h per night [35].
Conclusion Obstructive sleep apnea is a relatively common but frequently undiagnosed disease. Screening examination to diagnose sleep apnea is relatively easily available in patients with suspected sleep apnea. It can expedite the diagnostics and subsequent treatment in a sleep laboratory. Early diagnostics and therapy of sleep apnea improves not only the quality of life, but also improves (in case of good patient adherence to treatment) mortality and morbidity. Screening examination can be performed in outpatient settings.
Conflict of interest None declared.
Ethical statement Authors state that the research was conducted according to ethical standards.
Funding body None.
references
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Review article
Obstructive sleep apnea in outpatient care – What to do with? Monika Kamasová *, Jan Václavík, Eva Kociánová, Miloš Táborský Department of Internal Medicine I – Cardiology, University Hospital Olomouc and Palacký University Olomouc, Faculty of Medicine, I. P. Pavlova 6, 775 20 Olomouc, Czech Republic
article info
abstract
Article history:
Obstructive sleep apnea is a relatively common sleep disorder, which is on the increase in
Received 24 August 2017
the last decades. It significantly contributes to morbidity and mortality in all countries
Accepted 23 September 2017
worldwide. Obstructive sleep apnea is one of the most common causes of daytime sleepi-
Available online xxx
ness. Typical risk factors for obstructive sleep apnea in the normal adult population are male
Keywords:
of manifest cardiovascular disease, diabetes mellitus, and anomalies in the upper respira-
gender, obesity (preferentially central obesity), and increased neck circumference, presence Obstructive sleep apnea
tory tract. Early diagnosis and treatment improves not only the quality of life, but also
Screening
significantly decreases patient morbidity and mortality. Nowadays screening can be per-
Diagnostics
formed in outpatient settings using simple and readily available devices. Such screening can
Outpatient care
contribute to early diagnosis and treatment of obstructive sleep apnea. © 2017 The Czech Society of Cardiology. Published by Elsevier Sp. z o.o. All rights reserved.
Contents Introduction . . . . . . . . . . . . . . . . Definition and pathophysiology . Prevalence . . . . . . . . . . . . . . . . . . Clinical symptoms . . . . . . . . . . . Diagnosis and therapy . . . . . . . . Conclusion . . . . . . . . . . . . . . . . . Conflict of interest . . . . . . . . . . . Ethical statement . . . . . . . . . . . . Funding body . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . .
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* Corresponding author at: Department of Internal Medicine I – Cardiology, University Hospital Olomouc and Palacky University, Faculty of Medicine and Dentistry, I. P. Pavlova 6, 775 20 Olomouc, Czech Republic. E-mail addresses: [email protected] (M. Kamasová), [email protected] (J. Václavík), [email protected] (E. Kociánová), [email protected] (M. Táborský). http://dx.doi.org/10.1016/j.crvasa.2017.09.004 0010-8650/© 2017 The Czech Society of Cardiology. Published by Elsevier Sp. z o.o. All rights reserved.
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Introduction Obstructive sleep apnea is a relatively common disease with potential neurocognitive, cardiovascular and metabolic consequences [1]. According to the American Academy of Sleep Medicine (AASM) 2017 guideline, obstructive sleep apnea belongs, together with central sleep apnea and sleep related hypoventilation, to sleep-disordered breathing [2].
Definition and pathophysiology Obstructive sleep apnea is the most common type of the sleepdisordered breathing (SDB) characterized by episodes of upper airway collapse during sleep. These episodes cause cessation or significant reduction of airflow despite of ongoing respiratory efforts. In patients suffering from obstructive sleep apnea, airway dilating muscles can no more resist the negative pressure in airways during inspiration. The muscle tone is reduced during sleep and airways become contracted [3]. These episodes are typically accompanied by repeated oxyhemoglobin desaturation and terminated by short microarousals when the airway patency is restored. Sleep is fragmented and sympathetic nervous system is activated. Airway patency restoration is followed by hypercapnia, hypoxemia and subsequent compensatory hyperventilation. These events lead to fragmented sleep as the patient oscillates between wakefulness and sleep. In severe cases respiratory events can occur more than 100 times per hour; each event typically lasts 20–40 s [4]. Patients suffer from reduced deep NREM 3 and REM sleep [5,6]. In patients with obstructive sleep apnea, anatomic airway constrictions (enlarged tonsils, extended soft palate, and macroglossia) are often found. Obstructive sleep apnea severity is expressed by the apnea– hypopnea index (AHI), which is defined as the number of apnea and hypopnea events per hour of monitored sleep. Apnea is defined by complete obstruction of the upper airways lasting for at least 10 s (i.e. airflow restriction by more than 90% (according to AASM criteria)) (Table 1). Hypopnea is defined as
airflow restriction more than 30% (according to AASM criteria) lasting for more than 10 s. According to AHI, obstructive sleep apnea is categorized as mild (AHI 5–15 episodes/h), moderate (AHI 15–30 episodes/h), and severe (AHI ≥30 episodes/h). The oxygen desaturation index (ODI) is defined as the number of desaturations per 1 h of monitored sleep when oxygen saturation is reduced as compared to the baseline standard level. The respiratory effort related arousal (RERA) can also be used. RERA is defined as an episode characterized by an increased respiratory effort caused by upper airway airflow reduction resolved with arousal and accompanied in most cases with hypoxemia. The respiratory disturbance index (RDI) is the sum of RERA and AHI. According to the third edition of the International Classification of Sleep Disorders (ICSD-3), obstructive sleep apnea (OSA) is defined as polysomnography derived obstructive respiratory disturbance index (RDI) ≥5 events/h associated with typical OSA symptoms, or an obstructive RDI ≥15/h in the absence of clinical OSA symptoms. The American Academy of Sleep Medicine (AASM) defines obstructive sleep apnea as AHI (apnea–hypopnea index – see below) more than 15, or AHI larger than 5 in presence of symptoms [2].
Prevalence Prevalence of obstructive sleep apnea depends on the population studied (see Table 2). It is estimated to be 14% in men and 5% in women (OSA being defined as AHI ≥5 associated with clinical symptoms) (3). In some populations, prevalence of OSA can be higher (e.g. the estimated prevalence in patients undergoing bariatric surgery is 70–80%; prevalence is also higher in stroke patients) [7–9]. Higher prevalence is found in patients with ischemic heart disease [10], heart failure, resistant hypertension [11] (screening to exclude sleep apnea should be performed in all patients with resistant hypertension), in patients suffering from obesity [12], type 2 diabetes mellitus and arrhythmias like atrial fibrillation [13,14]. Studies have revealed that 82% and 93% of women with moderate and severe sleep apnea, respectively, remain undiagnosed [15].
Table 1 – Basic terms and definitions. Definitions Hypopnea Apnea Apnea–hypopnea index (AHI)
Respiratory disturbance index (RDI) Desaturation index (ODI) Respiratory effort related arousal (RERA)
Obstructive sleep apnea syndrome
Airflow restriction more than 30% (according to AASM criteria) lasting for more than 10 s Full airway closure lasting for at least 10 s (i.e. airflow restriction by more than 90% (according to AASM criteria)) Number of apnea and hypopnea events per hour of monitored sleep AHI 5–15 – mild sleep apnea syndrome AHI 15–30 – moderate sleep apnea syndrome AHI >30 – severe sleep apnea syndrome Sum of RERA and AHI Number of desaturations per hour of monitored sleep An episode characterized by an increased respiratory effort caused by upper airway airflow reduction resolved with arousal and accompanied in most cases with hypoxemia At least 5 episodes per 1 h of sleep (apnea or hypopnea) accompanied with some of the following symptoms: (1) excessive daytime sleepiness that cannot be explained by any other reason; (2) two and more of the following symptoms: choking or gasping, repeating arousals, daytime sleepiness, inability to concentrate, unfreshening sleep
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Table 2 – Sleep apnea prevalence. Sleep apnea prevalence Atrial fibrillation Myocardial infarction Resistant arterial hypertension Heart failure Obesity Stroke
% 32–49 60–65 64–83 50–68 71–78 50–70
Clinical symptoms The most common clinical symptoms of sleep apnea (see Fig. 4) include excessive daytime sleepiness and frequent daytime dozing off, fatigue, night insomnia, unrefreshing sleep, snoring, gasping during sleep, depressions, headache, decreased work performance, and dry mouth [2]. The main risk factors are obesity, metabolic syndrome, consumption of excessive food at bedtime, consumption of alcohol at bedtime, smoking, use of hypnotics and, in general, of medicines lowering the upper airway muscle tone, male gender, and irregular sleep. Correlation between the sleep apnea severity and higher alcohol consumption [16] and larger neck circumference is known. Although sleep apnea is considered to be a relatively newly described disorder, separate OSA case reports can be found in the 19th century medical journals [17]. Despite high OSA prevalence in the general population, this disease often remains undiagnosed because patients usually consider their symptoms to be normal. Inability to recognize a
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clinically significant obstructive sleep apnea syndrome (OSAS) can affect adversely the health condition, because the disease is related to significant morbidity and mortality. Excessive daytime sleepiness impairs severely the quality of life, cognitive performance, and social interactions [18,19]. Obstructive sleep apnea is related to three-to seven-fold increase of the number of traffic accidents [20]. Obstructive sleep apnea is an independent risk factor for development of cardiovascular disease, especially hypertension, but also ischemic heart disease, heart failure, and stroke [21]. Close relation to diabetes and metabolic syndrome development is also known. Untreated OSAS can bear increased health care cost.
Diagnosis and therapy Diagnosis of obstructive sleep apnea starts in a GP's clinic. Patients often come because their partner cannot sleep due to their snoring [22]. All patients should undergo physical examination and their history should be checked. In the out-patient care questionnaires are used to assess the probability of obstructive sleep apnea syndrome (Epworth Sleepiness Scale – Fig. 1; Berlin Questionnaire – Fig. 2, STOPBANG questionnaire, Sleep Apnea of Sleep Disorder Questionnaire SA-SDQ, and others). The available data show that, for example, the Berlin Questionnaire sensitivity is high; its lower specificity is caused by a high number of false positive results [23,24]. The Berlin Questionnaire is a useful assessment tool for the initial screening of patients with suspect obstructive sleep apnea. The questionnaire consists of three parts – the
Fig. 1 – Epworth Sleepiness Scale. Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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Fig. 2 – Berlin questionnaire.
first one is aimed at snoring, the second one at apnea during sleep and daytime sleepiness, and the third one at hypertension [25]. Score of 8 has been proposed as a cut-off value when patients should be examined for a sleep disorder [26]. According to a study performed by Brazilian physicians, positive correlation of the Berlin Questionnaire and the Epworth Sleepiness Scale has been proven (OSA diagnosis was confirmed in 94.75% of high-risk patients according to the Berlin Questionnaire while in 59.65% of high-risk patients according to the Epworth Sleepiness Scale) [27]. Polysomnography is considered to be the gold standard in the diagnosis of obstructive sleep apnea. It is currently performed by sleep laboratories. In outpatient care, level 4 screening devices can be used (e.g. ApneaLink, Somnocheck, etc.). They usually have one or two recording channels: one channel measures the airflow by a nasal cannula connected to a pressure sensor (providing the apnea–hypopnea index) and an oximeter monitoring blood saturation by oxygen. The above mentioned screening devices have been validated by clinical studies. They are easily available, easy to interpret and provide reliable AHI information as compared to level 1–3 devices [28,29]. Fig. 3 shows an assessment of ApneaLink record.
If the apnea–hypopnea index found out by ApneaLink is more than 15 the patient is sent for further comprehensive examination to a sleep disorder center. The current list of the individual sleep centers is available at www.sleep-society.cz. Polysomnography (or limited polygraphy) is performed there to confirm the diagnosis and the patients are treated, usually by pressure ventilation CPAP/BiPAP. Patients with severe sleep apnea proved by the screening (AHI 30 and up) associated with clinical symptoms evidencing sleep apnea syndrome should be examined in the sleep center preferentially. In patients with AHI 5–15 not associated with clear clinical symptoms of obstructive sleep apnea, the outpatient examination should be repeated and the patients should be then referred, depending on the result of the followup examination, to a sleep laboratory. Change of life style, early diagnosis of comorbidities and their treatment are important in therapy of obstructive sleep apnea. Change of life style includes body weight reduction, reduction of alcohol consumption, cessation of use of medicines (those influencing negatively the upper airway tone) and of smoking, change of sleeping position, etc. Tenpercent body weight reduction is known to reduce AHI by 26%
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Fig. 3 – (a) ApneaLink record proving severe sleep apnea. (b) ApneaLink record with physiological finding. The red arrow shows the airflow curve. The green arrow shows blood saturation by oxygen. (c) ApneaLink record with apnea. The red arrow shows airflow cessation and the green arrow the corresponding decrease of saturation.
Fig. 4 – Clinical symptoms of obstructive sleep apnea. *Adjusted according to CPAP guide (https://cpapguide.net/ sleep-apnea-symptoms-need-know/).
[30]. Continuous positive airway pressure (CPAP) is a preferred method of treatment of obstructive sleep apnea. CPAP is a form of non-invasive mechanical ventilation which forms continuous positive pressure in the airways [31]. In some cases, other forms of non-invasive ventilation can be used, e.g. bi-level positive airway pressure (BPAP), adaptive support ventilation
(ASV), etc. Oral appliances causing mandibular protrusion are an alternative to the pressure ventilation. Upper airway surgery can also be performed [32,33]. A recent study investigated whether treatment by continuous positive airway pressure (CPAP) therapy prevents the development of severe cardiovascular events [34]. The study
Please cite this article in press as: M. Kamasová et al., Obstructive sleep apnea in outpatient care – What to do with?, Cor et Vasa (2017), http://dx.doi.org/10.1016/j.crvasa.2017.09.004
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included 2717 patients (with moderate to severe obstructive apnea and manifest cardiovascular disease) who were randomized either to CPAP or standard therapy (life style measures). The primary endpoint was a composite of death from any cardiovascular cause, myocardial infarction, stroke, hospitalization for unstable angina, heart failure, or transient ischemic attack (TIA). The secondary endpoint was to assess the influence of quality of life, snoring, daytime sleepiness, and the patient mood. The patients were monitored for 3.7 years on average. According to results, CPAP decreased significantly the daytime sleepiness and improved quality of the patients' life; however, no reduction of severe cardiovascular events was observed. The study was limited by the fact that not all patients underwent polysomnography to exclude central sleep apnea. The average nocturnal duration of CPAP use (3.3 h) was relatively short in patients participating in the study [34]. Other randomized studies showed better results in patients treated by CPAP as compared to standard therapy if patients used the therapy for at least 4 h per night [35].
Conclusion Obstructive sleep apnea is a relatively common but frequently undiagnosed disease. Screening examination to diagnose sleep apnea is relatively easily available in patients with suspected sleep apnea. It can expedite the diagnostics and subsequent treatment in a sleep laboratory. Early diagnostics and therapy of sleep apnea improves not only the quality of life, but also improves (in case of good patient adherence to treatment) mortality and morbidity. Screening examination can be performed in outpatient settings.
Conflict of interest None declared.
Ethical statement Authors state that the research was conducted according to ethical standards.
Funding body None.
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