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In obstructive lung disease, there is difficulty with expiration (air trapping). There is poorly reversible airflow obstruction and an abnormal lung inflammatory response. Types of obstructive lung disease include:

  1. asthma

  2. COPD

  3. chronic bronchitis

  4. bronchiectasis

  5. cystic fibrosis

  6. emphysema.



OSA is defined as a sleep-related breathing disorder in which the airway is intermittently partially or fully obstructed by soft tissues above the larynx. This leads to episodes of apnoea, hypopnoea and hypoxaemia. This can cause severe and potentially fatal physiological effects. There is often associated obesity.

Long-term clinical effects

These may include:

  1. daytime sleepiness

  2. morning headaches

  3. snoring

  4. fatigue, tiredness, lack of energy

  5. pulmonary and systemic hypertension

  6. right and left ventricular hypertrophy and failure

  7. dysrhythmias

  8. polycythaemia

  9. respiratory failure.


The best test for OSA is the overnight polysomnography. This provides an apnoea-hypopnoea index (AHI). This number is the average number of apnoeas/hypopnoeas per h of sleep. AHI 5–15 is mild, 15–30 moderate and > 30 severe.

OSA can be inferred from the ‘STOP-BANG’ score:

  • S – do you Snore loudly?

  • T – do you often feel Tired, fatigued or sleepy during the daytime?

  • O – has anyone Observed your breathing stop during sleep?

  • P – do you have high blood Pressure?

  • B – do you have a BMI > 35?

  • A – are you Aged > 50 years?

  • N – do you have a Neck circumference > 40 cm?

  • G – Gender—are you male?

Five or more ‘yes’ answers indicates increased probability of moderate to severe OSA.

Other simple tests are:1

  1. FBC.

  2. Check renal function.

  3. HbA1c.

  4. Venous bicarbonate 27 mmol/L or greater.

  5. ECG—looking for abnormalities such as LVH, RVH, right heart strain and dysrhythmias.

Anaesthetic concerns

OSA may be associated with:

  1. difficult mask ventilation

  2. difficult intubation

  3. increased risk of aspiration.

Anaesthetic approach

Minimise opioids—see Bariatric surgery. Use alternative forms of analgesia e.g. paracetamol, NSAIDs or nerve blocks.

Postoperative concerns

The main concern is postoperative respiratory depression and hypoxia. The highest-risk patients have severe OSA, significant co-morbidities and major surgery under GA. The following is recommended for such patients.1

  1. The patient ...

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