Week 6 - Part 2 - Obstructive Sleep Apnoea PDF

WEEK 6: OBSTRUCTIVE SLEEP APNOEA EHR522: EXERCISE FOR METABOLIC AND MENTAL HEALTH CONDITIONS Subject Coordinator: Tim Miller [email protected] 02 6338 4442 OBSTRUCTIVE SLEEP APNOEA (OSA)  Obstructive sleep apnoea (OSA) is a common dis...

WEEK 6: OBSTRUCTIVE SLEEP APNOEA EHR522: EXERCISE FOR METABOLIC AND MENTAL HEALTH CONDITIONS Subject Coordinator: Tim Miller [email protected] 02 6338 4442 OBSTRUCTIVE SLEEP APNOEA (OSA)  Obstructive sleep apnoea (OSA) is a common disorder affecting at least 2 – 4% of the adult population  OSA is characterised by recurring upper airway obstruction during sleep  Common predisposing factors for OSA include  Gender (male)  Craniofacial anomalies  Obesity DEFINITIONS  Apnoea – Temporary cessation of breathing  Hypopnoea – Overly shallow breathing or an abnormally low respiratory rate. Defined by a decreased amount of air movement into the lungs and can cause oxygen levels in the blood to drop  Hypoxaemia – Abnormally low level of oxygen in arterial blood  Hypercapnia (Hypercarbia) – Abnormally elevated carbon dioxide levels in the blood DEFINITIONS  Apnoea – Hypopnoea Index (API) – The sum of the number of apnoea and hypopnoea events per hour of sleep  Respiratory Disturbance Index (RDI) – The sum of the number of apnoea, hypopnoea and arousals per hour of sleep  Retrognathia – A condition in which the lower jaw is set further back than the upper jaw, making it look like the person has a severe overbite  Macroglossia – Enlargement of the tongue OBSTRUCTIVE SLEEP APNOEA  The signs, symptoms and consequences of OSA are a direct result of the derangements that occur due to repetitive collapse of the upper airway  Sleep fragmentation  Hypoxaemia  Hypercapnia  Marked swings in intrathoracic pressure  Increased sympathetic activity HEALTH CONSEQUENCES  Many health consequences are associated with OSA, including  Lethargy  Memory loss  Problems with thinking and judgement  Disruption of normal metabolic functions  Cardiovascular disorders DIAGNOSTIC CRITERIA – COMPLEX…  Clinically, OSA is defined by the occurrence of daytime sleepiness, unintentional sleep episodes during wakefulness, unrefreshing sleep, loud snoring, witnessed breathing interruptions or awakenings due to breath holding, gasping or choking in the presence of at least 5 obstructive respiratory events (apnoeas, hypopnoeas or respiratory effort related arousals) per hour of sleep  The presence of 15 or more obstructive respiratory events per hour of sleep in the absence of sleep related symptoms is also sufficient for the diagnosis of OSA due to the greater association of this severity of obstruction with important consequences such as increased cardiovascular disease risk DIAGNOSTIC CRITERIA – COMPLEX…  Diagnostic criteria for OSA are based on clinical signs and symptoms determined during a comprehensive sleep evaluation, which includes  Sleep oriented history  Physical examination  Findings of sleep testing HISTORY  A comprehensive sleep history in a patient suspected of OSA should include an evaluation for  Snoring  Witnessed apnoeas  Gasping/choking episodes  Excessive sleepiness not explained by other factors (including assessment of sleepiness severity using the Epworth Sleepiness Scale)  Total amount of sleep  Nocturia  Morning headaches  Sleep fragmentation / sleep maintenance  Decrease concentration and memory HISTORY  An evaluation of secondary conditions that may occur as a result of OSA should also be obtained. This includes  Hypertension  CVA  MI  Cor pulmonale  Motor vehicle accidents PHYSICAL EXAMINATION  The physical examination can suggest increased risk and should include the respiratory, cardiovascular and neurological systems.  Particular attention should be paid to the presence of obesity, signs of upper airway narrowing or the presence of other disorders that can contribute to the development of OSA or the consequences of OSA PHYSICAL EXAMINATION  Features to be evaluated that may suggest the presence of OSA include  Increased neck circumference (> 17 inches in men, > 16 inches in women)  BMI ≥ 30  Modified Mallampati score of 3 or 4  The presence of retrognathia  Lateral peritonsillar narrowing  Macroglossia  Tonsillar hypertrophy  Elongated or enlarged uvula  High arched or narrow hard palate  Nasal abnormalities OBJECTIVE TESTING  Following the history and physical examination, patients can be stratified according to their OSA disease risk  Those patients deemed high risk should have the diagnosis confirmed and severity determined with objective testing  The severity of OSA must be established in order to make an appropriate treatment decision OBJECTIVE TESTING  The two accepted methods of objective testing are in-laboratory polysomnography and home testing with portable monitors  Portable monitors may be used to diagnose OSA when utilised as part of a comprehensive sleep evaluation in patients with a high pre-test likelihood of moderate to severe OSA OBJECTIVE TESTING  Polysomnography requires the following physiologic signals  Electroencephalogram (EEG)  Electrooculogram (EOG)  Chin electromyogram  Airflow  Oxygen saturation  Respiratory effort  Electrocardiogram (ECG) or heart rate  Additional recommended parameters include body position and leg EMG derivations OBJECTIVE TESTING  A portable monitor should, at a minimum, record  Airflow  Respiratory effort  Blood oxygenation  Portable monitors may be used in the unattended setting as an alternative to polysomnography for the diagnosis of OSA in patients with a high pre- test probability of moderate to severe OSA and no comorbid sleep disorder or major comorbid medical disorder CATEGORISATION OF SEVERITY  The measure of severity of OSA is based on the number of apnoea or hypopnoea events per hour of sleep, represented by the Apnoea Hypopnoea Index (AHI)  Parameters for OSA  Normal: AHI < 5  Mild: AHI ≥ 5 and < 15  Moderate: AHI ≥ 15 and < 30  Severe: AHI ≥ 30  The exact aetiology of OSA is unknown and has led to multiple treatment and management options TREATMENT - PAP  The American Academy of Sleep Medicine recommends the use of continuous positive airway pressure (CPAP) or oral appliances for treating mild to moderate OSA  CPAP is recommended as the first-line, and oral appliances as second-line, treatments for sever OSA  Although highly efficacious when used, the utility of CPAP is limited by poor patient adherence TREATMENT - PAP  PAP provides pneumatic splinting of the upper airway and is effective in reducing the AHI  PAP may be delivered in continuous (CPAP), bilevel (BPAP) or autotitrating (APAP) modes  Partial pressure reduction during expiration (pressure relief) can also be added to these modes  BPAP, pressure relief or APAP can be considered in the management of OSA in CPAP-intolerant patients. These may improve patient comfort and adherence TREATMENT – BEHAVIOURAL STRATEGIES  Behavioural treatment options include  Weight loss  Exercise  Positional therapy  Avoidance of alcohol or sedatives before bedtime  Successful dietary weight loss may improve the AHI in obese patients with OSA TREATMENT – BEHAVIOURAL STRATEGIES  Sleep position can affect airway size and patency with a decrease in the area of the upper airway, particularly in the lateral dimension, while in the supine position  Positional therapy, consists of a method that keeps the patient in a non-supine position  A positioning device (eg. alarm, pillow, backpack or tennis ball) should be used when initiating positional therapy TREATMENT – ORAL APPLIANCES  Custom made oral appliances may improve upper airway patency during sleep by enlarging the upper airway and/or by decreasing upper airway collapsibility (eg. improving upper airway muscle tone)  Mandibular repositioning appliances (MRA) cover the upper and lower teeth and hold the mandible in an advanced position with respect to the resting position  Tongue retaining devices (TRD) hold only the tongue in a forward position with respect to the resting position, without mandibular repositioning TREATMENT – ORAL APPLIANCES  Although not as efficacious as CPAP, oral appliances are indicated for use in patients with mild to moderate OSA who prefer oral appliances to CPAP, or who do not respond to CPAP, are not appropriate candidates for CPAP, or who fail CPAP or behavioural measures such as weight loss or sleep position change TREATMENT – SURGICAL  The first methods used to treat OSA were surgical  Surgical therapy includes a variety of upper airway reconstructive or by-pass procedures, often site- directed and/or staged  Evaluation for primary surgical treatment can be considered in patients with mild OSA who have severe obstructing anatomy that is surgically correctible  Surgical procedures may be considered as a secondary treatment for OSA when the outcome of PAP therapy is inadequate, such as when the patient is intolerant or PAP, or PAP therapy is unable to eliminate OSA ADJUNCTIVE THERAPIES – BARIATRIC SURGERY  Bariatric surgery is an effective means to achieve major weight loss and is indicated in individuals with a BMI ≥ 40 or those with a BMI ≥ 35 with important comorbidities and in whom dietary attempts at weight control have been ineffective  The remission rate for OSA two years after bariatric surgery, related to the amount of weight lost, is 40% ADJUNCTIVE THERAPIES – PHARMACOTHERAPY AND SUPPLEMENTAL OXYGEN  There are no widely effective pharmacotherapies for OSA with the important exceptions of individuals with hypothyroidism or acromegaly. Treatment of those underlying medical conditions can improve the AHI  Oxygen supplementation is not recommended as a primary treatment for OSA ADJUNCTIVE THERAPIES – PHARMACOTHERAPY AND SUPPLEMENTAL OXYGEN  Supplemental oxygen alone may reduce nocturnal hypoxaemia, but may also prolong apnoeas and may potentially worsen hypercapnia in patients with comorbid respiratory disease  Modafinil is recommended for the treatment of residual excessive daytime sleepiness in OSA patients who have sleepiness despite effective PAP treatment and who are lacking any other identifiable cause of their sleepiness A ROLE FOR EXERCISE?  Very few RCTs available that analyse the role of exercise in the management of OSA  Meta-analysis of the limited available studies shows that exercise in OSA  Decreases AHI  Reduced Epworth Sleepiness Scale  Minimal or no reduction in BMI  Marked heterogeneity of the exercise protocols used in the available RCTs limits the ability to make specific exercise recommendations for OSA patients A ROLE FOR EXERCISE?  Exercise has been shown to reduce the severity of other disorders and/or diseases associated with OSA, including  Diabetes  CVD  Hypertension  Obesity A ROLE FOR EXERCISE?  It is not fully understood how exercise reduces OSA symptoms, but research indicates that the impact of exercise on OSA is not related to a reduction in body mass or BMI  It is possible that no single mechanism is responsible and perhaps there is a complex interplay of factors associated with exercise training that leads to improvement in the severity of OSA A ROLE FOR EXERCISE?  A potential explanation cited for exercise reducing AHI in mild or severe OSA focuses on the comorbidity of obesity and OSA  Excess adipose tissue is the cause of the airway collapsing and apnoea or hypopnoea events occurring, and obesity is linked to increased adipose tissue in the pharyngeal airway  Exercise can lead to weight loss and reduction in BMI, and studies have suggested that reduction in BMI is associated with reduction in the volume of adipose tissue in the pharyngeal airway  However, research has reported that exercise reduces AHI regardless of significant reduction in BMI A ROLE FOR EXERCISE?  Exercise has been documented to achieve a 25 – 30% reduction in OSA severity. A dietary induced body mass reduction of 10% is required to achieve this same level of OSA severity improvement  Even modest improvements in OSA severity have been associated with significantly reduced risk of adverse health outcomes CONCLUSION  Exercise has an effect on reducing both AHI and Epworth Sleepiness Scale scores in patients with OSA, independent of BMI. This suggests a possible role for exercise in the treatment of sleep apnoea  This conclusion remains consistent independent of different types of exercise, durations of exercise, frequency of exercise sessions, CPAP usage, and supervised or unsupervised treatment programs  Although the effect size from exercise in AHI reduction seems smaller compared with CPAP and oral appliances, exercise training may be an ideal adjunct therapy, especially given its marked effects on sleep efficiency and daytime sleepiness