What are the steps in the oxygen transport pathway from air to tissues?
- Alveolar gas
- Alveolar membrane
- Arterial blood
- Regional arteries
- Capillary blood
What are the disease processes that may affect the oxygen transport pathway?
- Low inspired oxygen
- Muscle and chest wall problems
- Obstructive airway disease
- Pulmonary oedema
- Ventilation-Perfusion matching
- Peripheral arterial disease
What point in the oxygen transport pathway does low inspired oxygen affect?
What may cause low inspired oxygen?
What point in the oxygen transport pathway do muscle or chest wall problems affect?
What are some potential muscle or chest wall problems?
- Pectus Excavatum
- Muscular dystrophy
- Myasthenia gravis
What point in the oxygen transport pathway does obstructive airway disease affect?
Give two obstructive airway diseases?
What point in the oxygen transport pathway does fibrosis affect?
What are some potential causes of fibrosis?
What point in the oxygen transport pathway does pulmonary oedema affect?
As oxygen leaves the alveolar membrane
What are some potential causes of pulmonary oedema?
- Cardiogenic (left heart failure)
- Aspiration (e.g. vomit)
What point in the oxygen transport chain does ventilation-perfusion matching affect?
Just as the oxygen enters the arterial blood
What are some potential causes of problems with ventilation-perfusion matching?
- Pulmomary emboli
- Collapse of lobe
- Large airway destruction
What point in the oxygen transport pathway does anaemia affect?
What are some potential causes of anaemia?
- Insufficient red blood cells produced in marrow
- Deficiency of B12/iron
- CO binding
What point in the oxygen transport pathway does shock affect?
As oxygen is leaving arterial blood
What is shock?
Global poor perfusion
What point in the oxygen transport pathway does peripheral arterial disease affect?
What are some potential causes of peripheral arterial disease?
Local arterial insufficiency or damage to individual tissues, e.g. claudication or angina
What are the types of respiratory failure?
- Type 1
- Type 2
What are the features of type 1 respiratory failure?
- pO2 of arterial blood low
- pCO2 normal or low
What are the features of type 2 respiratory failure?
- pO2 of arterial blood low
- pCO2 high
What are the acute affects of respiratory failure?
Increase in CO2 and a decrease in O2
What is the increase in CO2 and a decrease in O2 in acute respiratory failure detected by?
What do the central chemoreceptors cause when they detect the increase in CO2 and a decrease in O2?
Breathlessness (some compensation)
What are the chronic effects of respiratory failure?
- CO2 retention
- Right heart failure (Cor pulmonare)
- Severely disabling
What is the result of CO2 retention in chronic respiratory failure?
- Cerebrospinal fluid acidity corrected by choroid plexus
- Initial acidosis corrected by kidney
- Reducation of respiratory drive
- Persisting hypoxia
What causes right heart failure in chronic respiatory failure?
It is the effect of hypoxia on pulmonary arteries resulting in pulmonary hypertension
How is respiratory failure managed?