Apnea, Obstructive Sleep

Alternative Names

  • OSA
  • Obstructive Sleep Apnea Syndrome
  • OSAS
  • Sleep Apnea/Hypopnea Syndrome
  • SAHS
  • OSAHS
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WHO-ICD-10 version:2010

Diseases of the nervous system

Episodic and paroxysmal disorders

OMIM Number

107650

Mode of Inheritance

Autosomal dominant

Description

Sleep apnea is a condition characterized by cessation of breathing when the individual is asleep, often for a minute or longer, several times throughout the night. The obstructive form of this condition, known as Obstructive Sleep Apnea (OSA), results from a physical closure of the airway during the person's sleep. As the breathing stops in affected people, they wake up momentarily, reopening the airway. Although patients may be able to go back to sleep immediately, the normal sleeping pattern is interrupted multiple times, resulting in a failure to attain the deep sleeping state which necessary for relaxation. Thus, affected patients appear not rested upon awakening, have morning headaches, limited attention and concentration, personality changes, and are sluggish and tired during the day. At night, they can be noticed by family members to be heavy snorers. In most affected people, the cause of this obstruction is a relaxation of the muscles supporting the soft palate, extending to the base of the tongue, during sleep. Obesity is a major risk factor for the development of OSA. As fat deposition increases on the sides of the upper airway, the airway narrows, and tends to close completely upon normal relaxation of the supporting muscles. Loss of muscle mass with increasing age is another factor for increased risk of development of OSA. In addition, males have a higher chance of contracting the condition, probably due to the effect of male hormones in causing structural changes in the airway. Other risk factors include anatomic abnormalities, enlarged tonsils, consumption of alcohol prior to sleeping, smoking, and/or nasal congestion. It is estimated that about 2% of women and 4% of men are affected by OSA.

Most OSA patients are unaware that their sleep pattern is disturbed and are at a loss for understanding the perpetual tiredness and behavioural changes they undergo. Sleep studies, also known as polysomnography, involves measuring the brain pattern, eye movements, muscle movements, oral and nasal airflow, the size and frequency of breaths, and the loudness of snoring to make an objective evaluation of OSA. Treatment strategies may differ according to the cause of the obstruction. In most cases, reducing obesity is a major goal of the treatment. Patients may be asked to abstain from drinking alcohol or taking sedatives from going to sleep. In some cases, a special mask can be worn over the nose and mouth, providing a mechanical breathing assistance. In extreme cases, surgery to remove either the tonsils or excess tissue at the back of the mouth may be required.

Obstructive sleep apnea can run in families. Affected members in such families have been noticed to share similarities in their facial and airway structures. Although no specific genetic marker has been found to be conclusively associated with OSA, it is assumed that obesity and OSA share a number of susceptibility genes. Several studies have indicated an increased probability of OSA among individuals carrying the ApoE4 allele.

Epidemiology in the Arab World

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Other Reports

Qatar

Ibrahim et al. (2007), in a prospective cross-sectional study, estimated the frequency of OSA among snorers in Qatar. From a total of 227 subjects who underwent polysomnography in the sleep clinic in a 3 year study period, 191 were found to meet the inclusion criteria of 'snorers'. A total of 75 of these patients were Qataris. According to their respiratory index score (RDI), the subjects were grouped as normal (RDI: 0-4.9; 34%), mild OSA (RDI: 5-14.9; 16.9%), moderate OSA (RDI: 15-29.9; 12.5%), and severe OSA (RDI: >30; 37.5%). Of the subjects, 126 (66%) had an abnormal RDI, indicating OSA. Interestingly, OSA was more frequent among non-Qataris (72.4%) as compared to Qataris (52%). Compared to the normal group, the OSA group had a significantly higher mean age (49.1 years vs. 46.2 years), significantly higher mean neck circumference, non-significantly higher mean BMI in males (34.3 vs. 33.6), higher number of reported witnessed apneas (67.5% subjects vs. 41.5% subjects), and a higher mean ESS (Epsworth Sleepiness Score;11.6 vs. 7.2). Among females diagnosed with OSA, the BMI was found to be significantly higher than the normal group. Multivariate logistic regression analysis revealed that ESS > 11, male gender, and witnessed apneas to be the most important predictors of OSA.

Dayyat et al. (2009) studied 206 non-obese habitually snoring children with polysomnographically diagnosed OSA and 206 obese children. Adenotonsillar size was larger in non-obese children, and conversely Mallampati class scores were significantly higher in obese children. Increased Mallampati scores in obese children led Dayyat et al. (2009) to suggest that soft tissue changes and potentially fat deposition in the upper airway may play a significant role in the global differences in tonsillar and adenoidal size among obese and non-obese children with OSA.

Saudi Arabia

Al-Mobeireek et al. 2000 studied sleep apnea syndrome (SAS) in a group of Saudi patients with aims to promote insight into the underdiagnosed disorder.  The study compared SAS associated factors between genders in 48 patients (28 male and 20 female).  Diagnosis was based on a history of sleep abnormalities, sleep monitoring tests, and response to treatment.  Using pulse oximetry, oxygen saturation dips was observed in all patients; polysomnography used on 18 patients indicated obstructive sleep apnea with an Apnea-hypopnea index of 56.5.  Male cases were significantly younger than female cases, however no difference was observed when factoring only obese cases.  Spirometry was performed by 39 patients, with 26 patients presenting values indicating obstructive or restrictive lung defects.  Arterial blood gas (ABG) measurement showed daytime hypoxemia and hypercarbia in 58% and 54% of patients respectively, attributed clinically to Obesity-Hypoventilation syndrome.  Female cases exhibited higher derangement in spirometry and ABG results, with significantly more severe obesity in female cases suggested as the cause.  Effective treatment involved nasal continuous positive airway pressure (CPAP).  Relatively ineffective surgery was performed for patients who could not afford CPAP.  The authors conclude frequent association of SAS with Obesity-Hypoventilation syndrome (94% of patients) and a relatively higher bias towards females compared to other studies; patients also presented with other disorders including Ischemic heart disease (31%) as well as systemic (60%) and pulmonary (23%) hypertension, supporting studies that associate SAS with these disorders.

[Al-Mobeireek AF et al. Clinical profile of sleep apnea syndrome. Saudi Med J. 2000; 21(2):180-3.]

Obstructive sleep apnea (OSA) was the subject of a study by Alotair et al. (2008) who sought to assess the differences in demographics, clinical presentation, and polysomnographic (PSG) results between 191 Saudi women and 193 Saudi men with the disorder. The study showed the following differences between the two groups: women were significantly older than men, body mass index was higher in the female group, sleep efficiency was lower in women and insomnia was less common among men. Additionally, women were more likely than men to be comorbid with hypothyroidism, diabetes, hypertension, cardiac disease, and asthma. Upon looking at the Apnea-hypopnea index (AHI), the researchers found that it was higher in men than in women; however, most of apnea/hypopnea events in women occurred during rapid eye movement sleep, and the duration of these events was significantly lower in women.

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