Obstructive Sleep Apnoea (OSA)

Last updated 08.03.13

Definition

-  Sleep disorder characterised by repeated interruptions to breathing (apnoeas)

-  Apnoea of >10 seconds duration

 

Features

-  Men > women

-  24% middle aged men

-  9% middle aged females

-  90-96% of cause of sleep apnoeas

-  Increased sympathetic nerve activity during apnoea

 

Causes

-  Collapse of upper airway

-  Sleep onset reduces pharyngeal muscle tone

-  Airway narrowing causes collapse on inspiration

 

DDx

-  Central Sleep Apnoa (CSA)

-  Ondines curse

-  Upper Airway Resistance Syndrome

 

Risk Factors

-  Males

-  Increasing age

-  Obesity (BMI >30)

-  25% not overweight

-  Neck circumference >42cm

-  Retrognathia or micrognathia

-  Enlarged tonsils

-  EtOH: relaxes pharyngeal muscles

-  Smoking: irritates & swells pharynx

-  Postmenopausal

-  Sleeping tablets (BZDs..): relaxes pharyngeal muscles

 

Associated S/S

-  Snoring

-  Apnoea

-  Followed by increased inspiritory drive

-  May last up to a minute

-  May occur hundreds of times per night

-  May only be noticed by partner

-  Hypoxia & hypercapnia results from obstruction

-  Sleep arousal

-  Daytime somnolence

-  Morning headaches

-  Impaired cognition, difficulty concentrating, learning & memory difficulties

-  Personality changes

-  Depression

-  Decreased libido & impotence in men

 

Complications

-  Excessive daytime sleepiness

-  Work & driving issues

-  Independant risk factor for

-  HTN

-  Insulin resistance

-  Assocaited with

-  AMI

-  Cardiac arythmia

-  Stroke

 

Ix

-  Investigate pts with snoring +1 other associated S/S

-  Polysomnography

-  Specialist unit

-  Respiratory, limb & EEG leads

-  +/- overnight observation

-  Home monitoring

-  Pulse oximetry & HR

-  +/- Resp monitor

-  Apnoea Hypopnea Index (AHI)

-  Derived from sleep study

-  Number of apnoeaa, hypopnoeas & sleep interruptions (total) divided by number of hours sleep

-  >5 = OSA

-  >30 = severe OSA

-  Epworth Sleepiness Scale

-  Assessment of severity of daytime somnolence

-  >10/24 = excessive daytime sleepiness

-  Sleep Physician R/V

-  Consider in all pts with a sleep study

-  Mandatory if

-  Uncertainty about test results

-  Severe cardiopulmonary conditions

-  Presence of 2 or more sleep disorders

-  Forensic investigations

 

Mx

-  Fitness to drive assessment

-  Assess bed partner for sleep deprivation

-  Lifesyle modification

-  Weight loss

-  Reduce evening EtOH (<2 standard drinks)

-  R/V of sleeping tablets

-  Quit smoking

-  Sleep on side or stomach: sew pouch for tennis ball onto back of pyjamas

-  CPAP

-  Gold standard treatment

-  Nasal or oronasal mask

-  Cumbersome but extremely effective therapy

-  70% pts tolerate long term therapy

-  Improves QOL, cognition, HTN

-  Reduces driving & cardiovascular risk

-  Mandibular Advancement Splint (MAS)

-  Made by a dentist (cheaper non-customised not recommended)

-  Hold mandible forward

-  Most effective for mild OSA, worse when supine in non-obese pts

-  Surgery

-  Limited indications (previously more common)

-  Uvulopalatopharyngoplasty (UPPP) improves snoring but unlikely to cure OSA

-  Tonsillectomy if enlarged tonsils contributory

-  Nasal surgery if nasal obstruction

 

Nasal CPAP

 

 

 

 

References

 

OSA Association

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