BTS sleep Course Module 10 Therapies I: Mechanical Intervention Devices (Prepared by Debby Nicoll and Debbie Smith) S1: Overview of OSA Definition History Prevalence Pathophysiology Causes Consequences Treatment options
Obstructive sleep apnoea syndrome Definition The obstructive sleep apnoea/hypopnoea syndrome is characterised by repetitive periods of upper airway narrowing or complete collapse during sleep leading to increasing inspiratory efforts, arousal, sleep fragmentation and daytime symptoms, most commonly, sleepiness.
Obstructive sleep apnoea History First recognised / described 1960 s Pickwickian Syndrome linked obesity, sleepiness, periodic breathing and cor pulmonale (without citing upper airway obstruction as the cause) much earlier First major breakthrough 1981 when an effective form of treatment described Prior to this, tracheostomy was the only treatment Prevalence (Davies and Stradling Thorax 1996;51:S65-S70) Detailed review of the prevalence literature (12 studies 1982 to 1995) conclude OSA occurs in 1-5% of adult men.
Obstructive sleep apnoea midline coronal section through the upper airway of a cadaver main area of airway collapse in OSA Pharyngeal muscles required to maintain patency Reason for recovery position and jaw thrust in unconscious subjects
Pathophysiology Balance of forces across the upper airway Obesity Small jaw Tonsils
Apnoea cycle
Causes of upper airway narrowing Obesity Upper body Neck circumference is a good predictor of sleep apnoea severity
Causes of upper airway narrowing Large tonsils Tissue growth, changes in fat deposition or swelling Acromegaly, hypothyroidism, oedema, loss of muscle tone alcohol and sedatives
Causes of upper airway narrowing Retrognathia and/or micrognathia is often the cause of OSA in non-obese patients
Consequences of airway narrowing Beginning of night 1 st hr 2 nd hr 3 rd hr 8 th hr Night time Increasing inspiratory efforts Snoring usually heard Hypoxaemia + hypercapnia 40-50 second apnoeas SaO 2 60% or lower Arousal from sleep Breathing resumed 400-500 apnoeas/ night (50-60 per hour) 60 minutes End of night
Consequences of OSA Night time (continued) Snoring, restless sleep, nocturnal choking attacks, nocturia, impotence, gastro-oesophageal reflux. Partners often report observing pauses in breathing Awake - air column (black) fully open Asleep - Air column collapsed behind tongue Asleep - air column collapsed from uvula to larynx Awake - air column fully open again
Consequences of OSA Daytime Morning headaches, unrefreshing sleep, personality changes and irritability. Daytime sleepiness (usual reason for treating OSA). Cognitive impairment documented, quality of life studies shown impairment similar or greater to that seen in many other chronic diseases. Accidents, including motor vehicle accidents are more common in patients with OSA, driving simulator performance is poor.
Consequences of OSA Long term consequences Respiratory failure Uncommon, unless complicated by chronic airflow limitation or very severe obesity ( Overlap syndrome ) Cardiovascular complications Hypertension
Results of the Pepperell trial Closed circles = subtherapeutic Open circles = therapeutic Average 24hr fall in mean BP 95% CI -3.3 mmhg -5.3 to -1.3 (p=0.001) Pepperell et al. Lancet 2001; 359; 204-10
Treatment options Mild/moderate disease without significant sleepiness: Weight control Avoidance of smoking, sedatives, evening alcohol and supine sleeping posture Sleeping semi propped up Improve nasal patency - nasal decongestants or, possibly, nasal surgery (poor nasal patency increases nasal resistance, decreasing negative intrapharyngeal pressure during inspiration) Soft palate surgery (uvelectomy, palatoplasty) and more radical pharyngeal surgery (uvelopalatopharyngoplasty (UPPP)) may improve snoring when severe and where no evidence of significant OSA.
Treatment options Oral appliances designed to hold the mandible and/or tongue forwards during sleep, may have a useful role Tonsillectomy alone is indicated in cases where the tonsils are significantly enlarged.
Treatment options In moderate to severe OSA + daytime sleepiness Nasal continuous positive airway pressure (CPAP) remains the most common treatment. CPAP first described in 1981 (Colin Sullivan). A portable pump produces pressurised air which the patient breathes via a closely fitting mask during sleep
Treatment options In patients with severe OSA, unable to tolerate CPAP, options are limited Gastroplasty can lead to considerable weight loss and resolution of OSA, but is unpleasant and involves considerable operative risks. Tracheostomy is extremely effective but side effects and limited patient acceptability.
Obstructive sleep apnoea - Summary Characterised by narrowing or complete collapse of the upper airway during sleep leading to increased inspiratory efforts, arousal and sleep fragmentation. Prevalence of up to 5% in adult men who tend to be obese, have a narrow pharynx, to snore, suffer from significant daytime sleepiness and in whom there is an increased risk of motor vehicle accidents. Moderate to severe OSA is associated with raised blood pressure. It can be effectively treated with nasal CPAP.