Obstructive Sleep Apnoea

Now this is a really cool respiratory condition that my medical school seems to really like. I mean, it’s not super common but it was mentioned a lot in our pre-clinical teaching for some reason.

In short, when these, usually obese, individuals are asleep their upper airways lose tone and flop close so they can’t breath and they wake up for a really short period, and start breathing again but they don’t really remember it and go back to sleep and this continues in cycles. So, they wake up the next day feeling like death.

On the respiratory ward in the last hospital I was at, they had a special Sleep Study Observation Room for investigation of these patients- i.e. creepily monitor them whilst sleeping. But, it was just being used for other patients because the NHS can’t afford to have an empty room.

And whilst I’m on that topic, bed shortages are a real thing. On my anaesthetics rotation, the theatre I was assigned to had to cancel their entire morning list because there were no beds for patients. The theatres are always waiting for patients to be found beds, and on the ward round, the nurses are always asking if the doctors can discharge a few patients because they need the beds. I don’t know what the solution is, but there needs to be one.


Obstructive Sleep Apnoea

Definition: disorder characterised by intermittent closure/ collapse of the pharyngeal airway causing apnoeic (cessation of breathing for 10 seconds or more) episodes during sleep. These are terminated by partial arousal.

Aetiology/ risk factors:

Apnoea occurs if the upper airway at the back of the throat is sucked closed when the patient breaths in. This occurs during sleep because the muscles that hold the airway open are hypotonic. Airway closure continues until the patient is woken up by the struggle to breathe against a blocked throat. These awakenings are so brief that the patient remains unaware of them but may be woken hundred of times at night leading to sleep deprivation and daytime sleepiness.

Contributing factors: alcohol ingestion before sleep, sedative use, obesity and COPD

                                           macroglossia, Marfan’s syndrome, craniofacial abnormalities

-Typically affect obese middle aged men (especially if fat around neck)

-It is more common in patients with hypothyroidism and acromegaly (macroglossia)

-Can also occur in children, particularly those with enlarged tonsils or adenoids

Epidemiology: affects about 2% of population

Prevalence increases with age

Symptoms:

-partner may describe apnoeic episodes during sleep, loud snoring, nocturnal choking

-daytime somnolence (drowsiness/ sleepiness)

-poor sleep quality

-morning headache or dry mouth

-decreased libido

-decreased cognitive performance  and difficult concentrating

-irritability, personality change

Signs:

-large tongue, enlarged tonsils, long or thick uvula, retrognathia (pulled back jaws)

-neck circumference (> 42cm males, > 40cm females) strongly correlated with presence of disease

-obesity and hypertension common

Investigations:

Epworth sleepiness scale– simple tool that helps discriminate OSA from simple snoring. The patient is asked how likely, or not, they would be to fall asleep in eight specified situations e.g. watching TV, sitting and talking to someone. High score = significant excess sleepiness.

Pulse oximetry, video recordings– during sleep, at home, may be all that is required for diagnosis

Polysomnography (inpatient sleep study): diagnostic. Monitors oxygen saturation, airflow at the nose and mouth, ECG, EMG chest (shows respiratory effort), and abdominal wall movement during sleep + video recording.

-The occurrence of 15 or more episodes of apnoea or hypopnoea during 1h of sleep indicates significant sleep apnoea.

Management:

-advice on sleep positions (sleep on side rather than on back)

-weight reduction (easier said than done)

-avoidance of tobacco and alcohol, sedatives and late night meals

-orthodontic devices such as mandibular advancement splints may be of benefit

Image result for mandibular advancement splint

CPAP (continuous positive airway pressure) via a nasal mask during sleep is effective in maintaining patency of upper airways and recommended by NICE for those with moderate to severe disease

-surgery to relive pharyngeal obstruction is occasionally needed (e.g. tonsillectomy, uvulopalatopharyngoplasty or tracheostomy)

Image result for uvulopalatopharyngoplasty

Uvulopalatopharyngoplasy

-Patient advised to inform DVLA

Complications:

-risk of accidents when driving or working

-worsening of congestive heart failure

-polycythaemia

-pulmonary hypertension, systemic hypertension (apnoeic episode –> hypercapnia –> increased systemic and pulmonary arterial pressure- can become sustained)

-increased risk of right heart failure, MI and stroke

-cardiac rhythm disturbance

-sudden death

Prognosis: short-term prognosis good with symptom improvement with CPAP. Compliance with advice or CPAP may be poor in long term.

References: Cheese & Onion, Rapid Medicine, Kumar and Clarke’s
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