Chronic ventilatory Failure Flashcards
What are the blood gas parameters which define chronic ventilatory failure?
Elevated pCO2 (> 6.0 kPA).
pO2 < 8 kPA.
Normal blood gas parameters
Elevated bicarbonate
How is chronic ventilatory failure differentiated from acute ventilatory failure?
Chronic= no change in blood PH
Acute= low blood ph
What type of respiratory failure is chronic ventilatory failure and why?
Type 2 because it has elevated PaCO2 and low PaO2
Name some of the conditions that can cause chronic ventilatory failure
Airways disease
• COPD
• bronchiectasis
Chest wall abnormalities
• kyphoscoliosis
Respiratory muscle weakness
• motor neuron disease (ALS)
• muscular dystrophy
• glycogen storage disease (Pompe’s disease) which results in an isolated diaphragm weakness
Central hypoventilation
• obesity hypoventilation syndrome
• congenital central hypoventilation syndrome (Ondine’s curse)
List some of the typical symptoms of chronic respiratory failure
- Breathlessness
- Orthopnoea (breathlessness lying flat- tends to occur in those with diaphragmatic or muscular weaknesses)
- Ankle swelling
- Morning headache (when carbon dioxide levels rise in the night, the excess carbon dioxide acts as a vasodilator within the cerebral blood vessels which can cause headache)
- Recurrent chest infections
- Disturbed sleep
How should chronic ventilatory failure be investigated?
- Lying and standing VC
- Mouth pressures/ sniff nasal inspiratory pressure
- Early morning ABG (at night chronic ventilatory failure is more evident because accessory muscles relax in the nighttime)
- Overnight oximetry
- transcutaneous CO2 monitoring (closely reflects the PCO2)
- Fluoroscopic screening of diaphragms to look for weakness
How is chronic ventilatory failure managed?
- Domiciliary Non Invasive Ventilation (NIV)
- Oxygen therapy
- Tracheostomy ventilation (t-IPPV)
treat the underlying cause!!!
