Diagnosing Obstructive Sleep Apnea - Reaching the Body of the Iceberg

Short Communication

Obstructive sleep apnea syndrome (OSA) consists of repeated upper airway occlusions accompanying arousals and desaturation episodes. Intrathoracic pressure alterations as well as desaturations may all cause multi-systemic outcomes [1-5]. Prevalence studies have revealed rates as 9-10% in middle age population however diagnosis of OSA is underestimated which might be due to unawareness of the disease by both the patient and the doctors [6,7]. "Occult" and therefore "untreated" sleep apnea may cause significant morbidities and mortality [4,8-13].

Clinical suspicion for OSA is the first step of the diagnosis. History confirming this suspicion such as complaints of snoring, witnessed apnea, daytime sleepiness, accidents due to sleepiness or presence of concomitant systemic disease/s are informative."Unrefreshing sleep" is a common complaint in those patients especially with more severe OSA and also patients may suffer from sore throat, fatigue, headache, night sweats, nocturia, insomnia, impotence symptoms at admission [14,15].

Most of the OSA patients are obese but should be kept in mind that approximately 40% of patients may be within normal BMI limits. Craniofacial structural features are more profound risk factor-rather than obesity in Asians.OSA is more frequent in male gender due to several factors such as longer and more collapsible airways and apple shape/truncal obesity. OSA risk increases with advanced age in both gender and this increase is more pronounced in the postmenopausal period among females [7,16].

Impact of upper respiratory tract on OSA is low except for the mechanical obstruction however examination must be carried out for both in OSA diagnosis and searching appropriate treatment option [17]. Upper airway endoscopy accompanied with Müller maneuver or during sleep may be performed for the estimation of possible obstruction site. Enlarged uvula tonsillar hypertrophy, retrognathia/presence of structural abnormalities such as micrognathia can also be identified. Soft tissue and bone evaluation is possible with cephalometry, CT or MR imaging.

Hypertension (HT) due to sleep apnea may be presented as various ways such as early onset HT (non-dipping HT) which is defined as higher tension levels in the morning than evening and resistant HT which is defined as untreated HT due to at least three anti hypertensive drugs [2,18]. Pulmonary HT is another important issue that may be more prevalent in patient with hypoventilation accompanying OSA or obstructive/restrictive lung pulmonary disease may be determined by echo. Diabetic patients may exhibit uncontrolled diabetes due to underlying sleep apnea. Presence of metabolic syndrome itself may also be a clue for clinician especially in a patient with complaints of OSA [3]. Similarly; patient may suffer from recurrent or untreatable rhythm problems [19]. All of these difficult to treat clinical circumferences should remind the clinician OSA.

Depressive symptoms are common in sleep apneic patients [20]. OSA related complaints such as daytime sleepiness and concentration deficit may be misdiagnosed as depression. Social isolation due to OSA related complaints may also cause depression. In both circumstances prescription of sedative and hypnotics may cause vicious circle deteriorating OSA.

There are subjective and objective tests for the assessment of sleepiness and sleep quality. Epworth sleepiness scale, which consists of a total of 8 questions and evaluates sleepiness state of the person 10 and higher ratings of sleepiness is assessed in favor of the use of assessment after treatment in patients may be appropriate [21]. In clinical practice; subjective tests may be insufficient in evaluating patients in which sleepiness score is low because actively working individuals may masquerade sleepiness with increased tea/coffee consumption or stimulants conscious/unconsciously or may be insufficient for elderly [22].

Stanford Sleepiness test consists of items from 1 to 7 and 7 reflects most sleepiness. Pittsburg sleep quality scale is another survey for assessment of sleepiness. Berlin questionnaire, STOP and STOPBANG tests are diagnostic surveys for evaluation of OSA probability. Objective tests in evaluating sleepiness are MSLT, MWT, pupillometry and Osler test although the latter two are not used routinely [23].

Polysomnography (PSG) is the gold standard test for diagnosis. There are 4 types of devices. Hospital based PSG can be performed via type 1 device which parameters such as EEG, ECG, EOG, leg movements, oxygen saturation are documented. Type 2 devices has similar features and suitable for use outside of a hospital. Information about whether sleeping is present or dependent on sleep stages (REMrelated?) cannot obtained in type 3 and 4 devices due to lack of EEG. Home sleep studies are recommended in subjects with moderate-tosevere probability OSA without co-morbid diseases [24,25].

As a result, the most important step in the diagnosis of OSA is suspicion and making referrals of patients to sleep clinics is important for public health. In high probability patients some recommendations such as avoidance of smoking/ alcohol/ sedatives/hypnotic drug; sleeping in non-supine position-if the patient describe position dependent worsening, warning if patient is working in a risky work or driving. Positive impact of exercise on decreasing respiratory disturbance should be mentioned. The treatment approach must include underlying disease-OSA rather than symptoms. Prompt diagnosis for preventing poor clinical outcomes is necessary.

References

1. Mansukhani MP, Calvin AD, Kolla BP, Brown RD Jr, Lipford MC, Somers VK, et al. The association between atrial fibrillation and stroke in patients with obstructive sleep apnea: a population-based case-control study. Sleep Med. 2013; 14: 243-246.
2. Torres G, Sánchez-de-la-Torre M, Barbé F. The relationship between obstructive sleep apnea and hypertension. Chest. 2015.
3. Uyar M, Davutoglu V, Aydin N, Filiz A. Comparison of metabolic syndrome with growing epidemic syndrome Z in terms of risk factors and gender differences. Sleep Breath. 2013; 17: 647-651.
4. Shah NA, Yaggi HK, Concato J, Mohsenin V. Obstructive sleep apnea as a risk factor for coronary events or cardiovascular death. Sleep Breath. 2010; 14: 131-136.
5. Vrints H, Shivalkar B, Hilde H, Vanderveken OM, Hamans E, Van de Heyning P, et al. Cardiovascular mechanisms and consequences of obstructive sleep apnoea. Acta Clin Belg. 2013; 68: 169-178.
6. Pizarro C, Schaefer C, Kimeu I, Pingel S, Horlbeck F, Tuleta I, et al. Underdiagnosis of Obstructive Sleep Apnoea in Peripheral Arterial Disease. Respiration. 2015.
7. Peppard PE, Young T, Barnet JH, Palta M, Hagen EW, Hla KM. Increased prevalence of sleep-disordered breathing in adults. Am J Epidemiol. 2013; 177: 1006-1014.
8. Young T, Finn L, Peppard PE, Szklo-Coxe M, Austin D, Nieto FJ, et al. Sleep disordered breathing and mortality: eighteen-year follow-up of the Wisconsin sleep cohort. Sleep. 2008; 31: 1071-1078.
9. Wang X, Ouyang Y, Wang Z, Zhao G, Liu L, Bi Y. Obstructive sleep apnea and risk of cardiovascular disease and all-cause mortality: a meta-analysis of prospective cohort studies. Int J Cardiol. 2013; 169: 207-214.
10. Cao J, Feng J, Li L, Chen B. Obstructive sleep apnea promotes cancer development and progression: a concise review. Sleep Breath. 2015; 19: 453-457.
11. Fusetti M, Fioretti AB, Valenti M, Masedu F, Lauriello M, Pagliarella M. Cardiovascular and metabolic comorbidities in patients with obstructive sleep apnoea syndrome. Acta Otorhinolaryngol Ital. 2012; 32: 320-325.
12. Mutter TC, Chateau D, Moffatt M, Ramsey C, Roos LL, Kryger M. A matched cohort study of postoperative outcomes in obstructive sleep apnea: could preoperative diagnosis and treatment prevent complications? Anesthesiology. 2014; 121: 707-718.
13. Simpson L, Hillman DR, Cooper MN, Ward KL, Hunter M, Cullen S, et al. High prevalence of undiagnosed obstructive sleep apnoea in the general population and methods for screening for representative controls. Sleep Breath. 2013; 17: 967-973.
14. Epstein LJ, Kristo D, Strollo PJ Jr, Friedman N, Malhotra A, Patil SP; Adult Obstructive Sleep Apnea Task Force of the American Academy of Sleep Medicine. Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. J Clin Sleep Med. 2009; 5: 263-276.
15. Seftel AD, Strohl KP, Loye TL, Bayard D, Kress J, Netzer NC. Erectile dysfunction and symptoms of sleep disorders. Sleep. 2002; 25: 643-647.
16. Won C, Guilleminault C. Gender differences in sleep disordered breathing: implications for therapy. Expert Rev Respir Med. 2015; 9: 221-231.
17. Georgalas C. The role of the nose in snoring and obstructive sleep apnoea: an update. Eur Arch Otorhinolaryngol. 2011; 268: 1365-1373.
18. Peppard PE, Young T, Palta M, Skatrud J. Prospective study of the association between sleep-disordered breathing and hypertension. N Engl J Med. 2000; 342: 1378-1384.
19. Hohl M, Linz B, Böhm M, Linz D. Obstructive sleep apnea and atrial arrhythmogenesis. Curr Cardiol Rev. 2014; 10: 362-368.
20. Lee W, Lee SA, Chung YS, Kim WS. The relation between apnea and depressive symptoms in men with severe obstructive sleep apnea: mediational effects of sleep quality. Lung. 2015; 193: 261-267.
21. Johns MW. A new method for measuring daytime sleepiness: the Epworth sleepiness scale. Sleep. 1991; 14: 540-545.
22. Onen F, Moreau T, Gooneratne NS, Petit C, Falissard B, Onen SH. Limits of the Epworth Sleepiness Scale in older adults. Sleep Breath. 2013; 17: 343-350.
23. Bennett LS, Stradling JR, Davies RJ. A behavioural test to assess daytime sleepiness in obstructive sleep apnoea. J Sleep Res. 1997; 6: 142-145.
24. Collop NA, Tracy SL, Kapur V, Mehra R, Kuhlmann D, Fleishman SA, et al. Obstructive sleep apnea devices for out-of-center (OOC) testing: technology evaluation. J Clin Sleep Med. 2011; 7: 531-548.
25. Oliveira MG, Garbuio S, Treptow EC, Polese JF, Tufik S, Nery LE, et al. The use of portable monitoring for sleep apnea diagnosis in adults. Expert Rev Respir Med. 2014; 8: 123-132.