58 Obstructive sleep apnoea Flashcards
you define and classify this condition
Apnoea is defined as cessation of airflow for more than 10 seconds.
Sleep disordered breathing encompasses obstructive and central sleep
apnoea.
Obstructive sleep apnoeas are present when there is persistent effort
without airflow.
Obstructive sleep apnoea syndrome is defined as OSA accompanied by
day-time symptoms such as hypersomnolence.
What are the predisposing factors for OSA syndrome?
Obesity
Increasing age
Male gender
Alcohol, sedatives, analgesics, anaesthetics
Smoking
Nasal obstruction
Pharyngeal/laryngeal obstruction
Endocrine /metabolic
Neuromuscular disorders
Chronic renal failure
What other symptoms may you elicit from the history?
Patients may commonly report restless or unrefreshing sleep, whilst their
partners may have witnessed apnoeic episodes. Less commonly, patients report
nocturnal sweating, morning headaches, nocturia and reduced libido.
What are the potential complications of OSA?
Cardiovascular
Hypertension
Right heart failure
Ischaemic heart disease
Cerebrovascular disease
Respiratory
Pulmonary hypertension
Hypoxaemia and hypercapnia
Endocrine
Reduced growth hormone/testosterone levels
Diabetic instability
CNS
Impaired cognition
Accident risk
Anxiety/depression
Chronic headache
GIT
Gastro-oesophageal reflux
What pathophysiological changes occur during an episode of
hypopnoea/apnoea?
During sleep, the narrow floppy airway in patients with OSA collapses as a
result of the decrease in dilator muscle activity and the sub-atmospheric
pressure generated during inspiration
Depending on whether the collapse is
partial or complete, snoring or apnoea will result. Arousal is caused by a
decreasing PaO2, increasing PaCO2 and increased respiratory efforts. The
arousal response is accompanied by an abrupt increase in BP and heart rate.
How is the diagnosis of OSA syndrome made?
Overnight polysomnography (PSG) is regarded as the gold standard
investigation. EEG and submental EMG are recorded for the purpose of
staging sleep, ECG, pulse oximetry, respiration and body position are
monitored. The PSG data is divided into epochs of 30s.
What treatment modalities are available?
Mild cases
Weight loss
Smoking cessation
Alcohol and sedative intake reduction
Mandibular repositioning devices
Moderate
Measures mentioned above
Nasal CPAP – pneumatically splints the airway
Severe
Initially bi-level non-invasive ventilatory support followed by CPAP once
control of respiratory failure has been achieved.
What is the role of surgery for OSA syndrome?
There is very little evidence that tongue base reduction or
uvulopalatopharyngoplasty confers any significant long lasting benefit.
Where OSA is due to tonsillar or adenoid hypertrophy or tumours of the larynx or
pharynx, the surgical treatment is clear.
Life threatening OSA may require a tracheostomy.
How would you manage this patient peri-operatively?
Pre-operative assessment must establish:
Severity and complications of the apnoea
Causes of OSA
Mode of treatment and compliance.
Anaesthetic management depends on:
Anaesthetic management depends on:
Impact of the surgery on the OSA
Requirements for post-operative analgesia
Pre-operatively, patients who use CPAP should take the equipment with them
to theatre and the staff should be instructed in its use.
Intra-operatively a regional technique will circumvent issues of airway
maintenance and suppression of arousal responses. Where a general
anaesthetic is considered, a difficult intubation should be anticipated. Opioids
should be used with care.
Post-operative care should involve nursing in an appropriate environment
with the application of CPAP if required.
