Sleep Disorders - OSA, Obesity Hypoventilation Syndrome And Narcolepsy

Obstructive Sleep Apnea (OSA) manifests as airway obstruction during sleep, isolated from central sleep apnea due to its lack of effect on the respiratory center. Anatomical abnormalities of the upper airway, obesity, and familial disposition constitute significant risk factors for OSA. The condition carries elevated risks for hypertension, type 2 diabetes mellitus, and pulmonary hypertension, potentially increasing mortality. Consequently, individuals with OSA often experience reduced quality of life.

Pathophysiology

Sleep apnea, characterized by recurrent episodes of upper airway obstruction, arises from a combination of physiological changes during sleep and anatomical abnormalities or obesity. This obstruction leads to hypoxia, triggering increased respiratory efforts and micro arousals that disrupt sleep continuity and quality. Micro arousals, reflected on EEG as intermittent alpha waves, contribute to daytime sleepiness, lethargy, and impaired quality of life.

Moreover, hypoxia and respiratory strain activate mechanisms that elevate sympathetic nervous system activity and the secretion of counter-regulatory hormones such as cortisol, adrenaline, and glucagon. This hormonal cascade promotes insulin resistance, increasing the risk of developing type 2 diabetes mellitus. Furthermore, these mechanisms contribute to the development of hypertension and, in combination with diabetes, can lead to dyslipidemias and increased cardiovascular risk, with potential complications including stroke, heart attack, or death.

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Diagnosis

Polysomnography (PSG), as defined by the American Association of Sleep Medicine (AASM), remains the gold standard for diagnosing obstructive sleep apnea (OSA). PSG involves monitoring multiple physiological parameters, including electroencephalography (EEG), electrooculography (EOG), electromyography (EMG), airflow, and oxygen saturation (SpO2). Home sleep apnea testing (HSAT) offers a limited evaluation, measuring only SpO2 and respiratory parameters without EEG. HSAT is less expensive and more convenient, but its diagnostic accuracy is inferior to PSG. OSA is diagnosed when an AHI of ≥5 events/hour is accompanied by signs and symptoms of OSA, or when an AHI of ≥15 events/hour occurs without symptoms. Significant daytime sleepiness, impaired quality of life, and snoring or gagging episodes during sleep are common symptoms of OSA.

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Apnea Hypopnea Index (AHI)

Apnea is defined as the whole cessation of airflow thru the airway for greater than 10 seconds, observed via improved respiration attempt. Alternatively, a discount in airflow of over ninety% for more than 10 seconds can also be considered apnea. Hypopnea, however, is characterised by means of a lower in airflow of greater than 50% for 10 seconds, in conjunction with elevated respiratory attempt and desaturation of 3% or more. AHI, or Apnea-Hypopnea Index, is calculated by adding the wide variety of apnea and hypopnea episodes according to hour of sleep. 

RERA, or Respiratory Effort-Related Arousal, includes episodes of reduced airflow with accelerated respiration attempt and arousal. RDI, or Respiratory Disturbance Index, is the overall wide variety of apnea, hypopnea, and RERA occasions in line with hour of sleep. An AHI of five or extra in line with hour with signs and symptoms and signs indicates obstructive sleep apnea, at the same time as an AHI of 15 or more in keeping with hour without signs and symptoms and signs and symptoms additionally shows the presence of OSA.

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Management

Risk elements related to obstructive sleep apnea (OSA) should be addressed directly so that you can enhance patient consequences. The widespread recommendation for treating OSA is to goal weight problems, as extra weight can exacerbate the situation. However, it's miles important to observe that remedy have to no longer be confined to simply dealing with OSA signs. Definitive remedy is warranted if OSA is observed through impaired satisfactory of life, accelerated daylight hours sleepiness, or high blood pressure.

 Daytime sleepiness may be assessed the use of the Epworth sleepiness rating, with a score of over 11 indicating the want for treatment initiation. The preferred treatment option is non-stop wonderful airway pressure (CPAP), despite the fact that it can be associated with facet outcomes which include nasal stuffiness, rhinitis, and claustrophobia. In instances wherein CPAP is not properly-tolerated, adjunctive treatments like weight reduction or top airway surgical procedure can be considered, in particular if anatomical abnormalities are gift.

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Recommendations of American Association for Study of Sleep 

Successful nutritional weight reduction has been shown to improve the Apnea-Hypopnea Index (AHI) in obese patients with Obstructive Sleep Apnea (OSA). It is important to combine dietary weight reduction with the number one remedy for OSA, Continuous Positive Airway Pressure (CPAP). In some cases, bariatric surgical procedure can be considered as an adjunctive remedy for overweight sufferers with OSA. When thinking about pharmacological agents for OSA remedy, SSRIs, Protriptyline, Methylxanthine derivatives, and Estrogen therapy aren't encouraged. 

Oxygen supplementation and short-performing nasal decongestants also are now not encouraged as primary remedies. However, topical nasal corticosteroids may additionally improve AHI in patients with OSA and rhinitis. Position remedy can be powerful as a secondary or supplemental therapy for those with a low AHI inside the non-supine position compared to the supine position.

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Obesity Hypoventilation Syndrome(OHS)

Obesity hypoventilation syndrome (OHS) provides with reduced breathing attempt and shares comparable pathophysiology with obstructive sleep apnea (OSA). Symptoms consist of expanded daylight hours sleepiness, hypoventilation main to hypoxia, and microarousals. OHS is usually seen in overweight sufferers, who're prone to each OHS and OSA. Diagnosis, according to AASM 3.0 pointers, includes a BMI ≥ 30, sunlight hours hypoventilation, and wakeful arterial blood gas showing hypercapnia (PCO2 > 45 mmHg). Management involves CPAP as first-line remedy, weight loss of 25 to 30% (even though whole development is not always sensible), and bariatric surgery for achieving huge weight reduction. It is essential to don't forget the coexistence of OAS and OHS in sufferers with unresolved signs.

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Narcolepsy

Narcolepsy is a neurological ailment characterised with the aid of multiplied daylight sleepiness and different signs and symptoms consisting of insomnia at night, unexpected muscle tone decrease, and hallucinations. It is believed to be an autoimmune disease, with a better frequency seen in H1N1 infections. The American Association of Sleep Medicine classifies narcolepsy into type 1 and sort 2, primarily based on particular criteria together with the presence of cataplexy and sleep onset REM phase. Management of narcolepsy involves medications inclusive of sodium oxybate for cataplexy and stimulant capsules like modafinil for daylight sleepiness. It is critical to correctly diagnose and treat narcolepsy to improve the satisfactory of life for the ones affected.

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