Chronic Ventilatory Failure

Question 1

What parameters define chronic ventilatory failure?

Answer 1

Elevated PCO2 (>6.0kPa).
Elevated bicarbonate.
PO2 < 8.0kPa.
Normal blood pH.

Question 2

What is the aetiology of chronic ventilatory failure?

Answer 2

Airways disease - COPD, OSAS, bronchiectasis.
Chest wall abnormalities - kyphoscoliosis.
Respiratory muscle weakness - ALS.
Central hypoventilation syndrome - obesity, congenital.

Question 3

What are the symptoms of chronic ventilatory failure?

Answer 3

SOB, orthopnoea.
Ankle oedema (hypoxic cor pulmonale).
Morning headache.
Recurrent chest infections.
Disturbed sleep.
Suspected neuromuscular disease (paradoxical abdominal wall motion).

Question 4

What are investigations of neuromuscular disease?

Answer 4

LFTs - lying and standing VC, mouth pressures, reduced FEV1 and FVC.
Hypoventilation assessment - early morning ABG, overnight oximetry, transcutaneous CO2 monitoring.
Fluoroscopic screening of diaphragms.

Question 5

What is the treatment of neuromuscular disease?

Answer 5

Domicillary Non-Invasive Ventilation (NIV).
Oxygen therapy.