What (11) are the causes of daytime sleepiness?
How (3) does Respiratory Control Change at Sleep Onset?
•Loss of the wakefulness drive to breathe and behavioural influences
•Several other respiratory control mechanisms are down-regulated
–Respiratory reflexes
–Chemosensitivity
–Upper airway and respiratory pump muscle tone: Upper airway resistance increases
•CHEMICAL CONTROL IS THE MAJOR REGULATOR OF BREATHING DURING SLEEP
Symptoms of Sleep Apnoea
3 cardinal features:
•Heavy snoring
•Excessive daytime somnolence
•Witnessed apnoeas
Nocturnal
•disrupted / restless/ unrefreshed sleep
•nocturnal choking, gasping
•Nocturia
Daytime
•headaches - nocturnal / morning
•memory / cognitive / concentration deficit
•mood change - depression / irritability
•sexual dysfunction - reduced libido / impotence
•Uncontrolled hypertension
(5) Neuropsychological effects of obstructive sleep apnoea
–Excessive sleepiness –Psychologic problems –Stroke –Dementia –In children, behavioural problems, poor school performance, ADHD
What (2) do the consequences of OSA relate to?
Sleep fragmentation
Hypoxia
-> reduced productivity, sociability & increased car/work accidents
(5) Cardiorespiratory effects of obstructive sleep apnoea
–Hypertension –Cor Pulmonale –Myocardial infarction –Arrhythmias / Sudden death –Polycythaemia
5 major OSA risk factors
(4) Pathogenesis of OSA
•Anatomically narrow upper airway
–Wakefulness - reflex dilator tone - patency
–Sleep - loss of this tone → Obstruction
Describe the pathophysiology of OSA
Sleep -> reduced upper airway dilator activity -> airway “closes” -> snoring.
Reduced PO2, increased PCO2 -> increased respiratory effort -> arousal.
With arousal, airway “opens” & increased upper airway dilator activity -> back to sleep.
Cycles again.
How do you diagnose OSA?
AHI (apnoea-hypopnea index) >5 events per hour (events/total sleep time)
Severity by AHI:
Define apnoea
Complete cessation of airflow for 10 seconds or longer regardless of oxygen desaturarion
Define hypopnoea
30% or more reduction in airflow associated with 3% oxygen desaturation or an alpha wave arousal from sleep
Mx of OSA
–Deciding to treat –Conservative treatments: weight loss, avoid alcohol, tobacco, sedatives, body position. Treat nasal congestion & medical disorders e.g. hypothyroidism –CPAP –Oral appliances –Surgery –Other
(3) types of sleep disordered breathing
Discuss central sleep apnoea
Apnoeas or hypopneas caused by reduction in central respiratory drive (CNS)
Aetiology •cardiac failure (Cheyne Stokes Respiration) •High altitude •CNS disorders - e.g. CVA •Idiopathic
Mx of central sleep apnoea
Cheyne-Stokes •treat heart failure •CPAP ( Naughton 1995) •? O2 •Servoadaptive ventilatory support
Idiopathic
–?O2
–? Non invasive ventilation
(5) causes of hypoventilation
•Reduced respiratory centre activity
–Reduced drive
–Suppression of activity by drugs, trauma, vascular accidents etc
•Neuromuscular disease
–nerve paralysis (drugs, polio, Guillian- Barre, trauma etc)
–muscle weakness (drugs, motor neurone disease, muscular dystrophy)
ALL forms of hypoventilation are worse in sleep
What might be stopping this man from getting to sleep?
Chronic Insomnia
Describe chronic insomnia
What are associated features of insomnia that have bidirectional links?
Disorders of anxiety, mood, impulse control & substance abuse
What genetic factor may play a role in insomnia?
Serotonin receptor abnormalities
FMHx
Describe ‘primary’ insomnia
Contributing disorders of insomnia
OSA, Circadian Disorders, Restless Legs, Psychiatric Disorders (50%), Substance abuse, Pain, Urinary problems, Medications
Ix of insomnia
Sleep diary
Actigraphy