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Chapter: Medicine Study Notes : Respiratory

Sleep Apnoea

Varies according to circadian cycle: two sleep gates each day, 2 – 3 pm and 10 – 11 pm (correlates with ­melatoin)

Sleep Apnoea



·        Varies according to circadian cycle: two sleep gates each day, 2 – 3 pm and 10 – 11 pm (correlates with ­melatoin)


·        Obstructive sleep apnoea is the most common cause of excessive sleepiness. ® MVA (driving drowsy is the same as driving drunk)


·        Causes of ­day time sleepiness:

o   Insufficient sleep (eg sleep restriction)

o   Obstructive sleep apnoea

o  Central sleep apnoea: absent or diminished ventilatory drive. Variety of causes including neuromuscular and chest wall deformities

o  Cheyne-Stokes Respiration: usually with advanced heart failure. Destabilisation of respiratory control centres

o  Upper airway resistance syndrome (no actual apnoea)

o  Periodic limb movements in sleep (PLMS: associated with restless leg syndrome) ® fragmented 

o   sleep. Also hot legs at night, cramps. Occurs in renal failure and anaemia. Treatment: codeine or anti-Parkinson drugs 

o  Narcolepsy: Normal sleep at night and frequently going to sleep during the day. (Sleep study looks at daytime napping more than nighttime). Goes into REM sleep early. Equivalent to 48 hours sleep deprivation, vivid dreams (hypnogogic hallucinations), HLA linkage, affects young, twice as common as MS. Can also be complicated by cataplexy (sudden loss of muscle tone in response to emotional stimuli). Treatment: stimulants during the day 

o  Idiopathic hypersomnolence

o  Drugs: alcohol, sedatives

o  Psychiatric

o  Hypothyroid

o  Anaemia

·        Normal breathing: 

o  Inspiration: uses Genioglossus and other muscles to dilate trachea, and intercostals and diaphragm to create negative pleural pressure

o  Expiration: much more passive

·        Normal changes during sleep:

o  Carotid bodies much less sensitive to ­CO2 and ¯O2

o  ¯Intercostal & accessory muscle tone 

o  ® ¯tidal volume ® ¯ventilation ® ­PCO2 by 5 mmHg ® ­HR, flushed, warm periphery


Obstructive Sleep Apnoea Syndrome


·        Pathogenesis: ¯muscle tone + anatomical factors (eg obese) + neural factors (eg stroke) ® upper airway narrows ® apnoea due to collapse ® arousal ® impairment overtime of sensitivity to daytime ­PCO2


·        Epidemiology:

o  Prevalence = 4% of adult population

o  More common in:

§  Men and post-menopausal women

§  Middle age

§  In kids with facio-cranial syndromes

§  Short jaw

§  Alcohol users

§  Over weight

·        Symptoms: Loud snoring, apnoea, daytime tiredness, early morning headache

·        History questions:

o  When do you go to bed and when do you get up (sleep restriction)

o  Do you snore, in any posture (the norm with OSAS).  Need witness accounts

o  Do you feel refreshed on waking

o  Where do you fall asleep (normal places but more often)

o  Other medical conditions: depression, anaemia, hypothyroidism, etc

o  Medications and when do you take them: can keep awake at night or make you sleepy during the day

·        Consequences:


o  ¯concentration, ¯memory, ­accident risk, ¯libido, premature mortality, hypertension, MI, CVA, precipitate respiratory failure in mild CORD


o  In kids: less apnoea (if there is apnoea then ?SIDS/epilepsy), more noisy breathing/restlessness, wake a lot at night, hyperactive during the day, growth delay (¯GH secretion due to ¯slow wave sleep)


·        Diagnosis requires sleep study ® Polysomnography. Measures muscle movements, airflows, O2 and CO2, EEG waves, eye movements, ECG etc during sleep

·        Treatment:

o   Conservative:

§  Weight loss (did it start with weight gain?), smoke reduction, sleep posture modification

§  Nasal CPAP for moderate/severe: air splint prevents airway collapse through whole breath cycle. Need to titrate pressure

§  Treat allergic rhinitis

§  Medication: Sleeping pills make it worse – stop them

§  Dental devices

o   Surgery:

§  Kids – tonsils and adenoids.

§  Adults:

·        Mandibular advancement

·        Gastric bypass ® ¯weight

·        Tracheostomy

·         Uvulopalatopharygnoplasty (UPPP) – but doesn‟t deal with all sites of occlusion and stops

§  CPAP working


Treatment of Insomnia 

·         A distressing complaint – not an illness 

·         Normal aging increases wakefulness during last 4 hours of sleep (reassure patient insomnia is „normal‟)

·         Non-drug management:

o   First check for: anxiety, depression, comfort, incontinence (eg diuretics), dementia, and treat these

o   Obtain careful sleep history, note factors improving/worsening sleep

o   Good explanation

o   Good Sleep Habits (Sleep Hygiene):

§  Reduce light, noise and extremes of temperature

§  Ensure physical security

§  Avoid caffeine, nicotine and alcohol before bedtime

§  No heavy meal for 2 hours beforehand, but have a light snack if hungry 

§  Regular exercise last in the afternoon/early evening, but nothing vigorous for 3 hours beforehand

§  Allow one hour of quiet activity before bedtime (reading, TV, music)

§  Develop a bedtime ritual, cleaning teeth, reading, etc

§  Don‟t go too early (ie before you feel sleepy) 

§  Don‟t stay in bed if you are awake. If not asleep within 15 – 20 minutes (estimate – don‟t use a clock), get up, go elsewhere and do something mundane until you feel sleepy again 

§  Get up at the same time in the morning: don‟t sleep in in weekends or after late nights. This helps train your body clock

§  Don‟t nap during the day

§  Don‟t worry if you can‟t get to sleep at night: worry will delay sleep even more

·         Drug management:

o   30% over 65 take sleeping pills 

o   Not for persistent insomnia (common in personality disorders, depression, sleep apnoea, pain, gastro-oesophageal reflux – treat primary cause).

·         Hypnotics should only be prescribed for symptomatic temporary insomnia (no more than 2 – 3 weeks) and should only be part of an overall management strategy

·         If used, for defined period, perhaps intermittently, and should sustain sleep

·         Not: 

o   Short acting (eg midazolam) get them off to sleep – but don‟t sustain sleep. Don‟t have any impact on early morning wakefulness. So will wake, and take another – then hangover in the morning, ­falls, etc 

o   Long acting (triazolam/Halcyon) - which leads to daytime anxiety

·         Use intermediate-acting hypnotics (eg zoplicone and temazepam)

·         Risk of addiction

·         Shift workers should avoid them


·         Differential:

·         Sleep disturbance: eg anxiety, sleep apnoea, narcolepsy,

o   Depression

o   Anaemia

o   Endocrine: hypothyroidism, hypocortisol (Addison‟s), diabetes, hypercalcaemia (due to ­PTH)

o   Infection (eg EBV)

o   Cancer

o   Drugs: alcohol intoxication, sedative drugs,

o   Head injury (eg subdural haematoma)

o   Post ictal states

o   Hypoglycaemia

o   Hepatic encephalopathy, Wernicke‟s encephalopathy

o   Chronic heart failure

o   Malabsorption (eg coeliac disease)

o   Pregnancy


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