Chronic Ventilatory Failure

Question 1

What defines chronic ventilators failure on an arterial blood gas?

Answer 1

Elevated pCO2
pO2 < 8 kPA
Normal blood pH
Elevated blood bicarbonate

Question 2

What is the difference with acute ventilatory failure?

Answer 2

You get an acute increase carbon dioxide partial pressure but you get a low blood pH

Question 3

What is chronic ventilators failure sometimes known as?

Answer 3

Type II respiratory failure

Question 4

How is type I respiratory failure different?

Answer 4

You have a low partial pressure of carbon dioxide and oxygen.

Question 5

What are the main examples of chronic ventilators failure?

Answer 5

Airways disease
Chest wall abnormalities
Respiratory muscle weakness
Central hypoventilation

Question 6

What airways diseases cause chronic ventilators failure?

Answer 6

COPD and bronchiectasis

Question 7

What chest wall abnormalities cause chronic ventilators failure?

Answer 7

Kyphoscoliosis

Question 8

What respiratory muscle weakness conditions result in chronic respiratory failure?

Answer 8

Motor neurone disease
Muscular dystrophy
Glycogen storage disease

Question 9

What central hypoventilation conditions cause chronic ventilatory failure?

Answer 9

Obesity hypoventilation syndrome

Cogenital central hypoventilation syndrome

Question 10

What are the main symptoms of chronic ventilatory failure?

Answer 10

Breathlessness
Orthopnea (breathlessness lying flat)
Ankle swelling 
Morning headache 
Recurrent chest infections 
Disturbed sleep

Question 11

What is cor pulmonale?

Answer 11

Chronic low PO2 can result to hypoxia vasoconstriction within the pulmonary vasculature which can result in elevated pressures within the right heart and these pressure are transferred to the venous system including the leg veins and fluid can leak out of the veins and cause swelling

Question 12

Why can people with chronic ventilatory failure get morning headaches?

Answer 12

Overnight when you are sleeping the are builds up of carbon dioxide and this carbon dioxide acts a vasodilator within the cerebral blood vessels and this cerebral vasodilator can lead to headaches.

Question 13

What are examinations findings of chronic ventilatory failure?

Answer 13

Paradoxical abdominal wall motion

Ankle oedema

Question 14

What is paradoxical abdominal wall motion?

Answer 14

Due to weakness of diaphragm, when a person is lying on their back and breathing, this leads to the diaphragm moving up during inspiration instead of moving down.

Question 15

What investigations are carried out for chronic ventilatory failure?

Answer 15

Lung function
Assessment of hypoventilation
Fluoroscopic screening of diaphragm

Question 16

What lungs function investigations are carried out during chronic ventilatory failure?

Answer 16

Lying and standing vital capacity

Mouth pressure/ Sniff Nasal Inspiratory Pressure

Question 17

What test would be done for the assessment of hypoventilation in chronic ventilation failure?

Answer 17

Early morning Arterial blood gas
Overnight oximetry
Transcutaneous CO2 monitoring

Question 18

Why does underventilation occur in sleep first?

Answer 18

During sleep (dreaming), all skeletal muscles are inactivated except for the diaphragm. However the accessory muscles are all inactivate. If you have ventilatory failure you will have to use those accessory muscle during R.E.M. sleep.

Question 19

What is REM sleep?

Answer 19

Dreaming

Question 20

What does a high FEV1/FVC ratio mean?

Answer 20

Restrictive lung disease

Question 21

What is the treatment for chronic ventilatory failure?

Answer 21

Domicilary non invasive ventilation

Oxygen therapy