L23. Physiology of Breathlessness Flashcards
What is breathlessness?
A group of sensations with multiple qualitative descriptors making an all-embracing definition is difficult.
When does breathlessness arise?
When there is a RECOGNITION by a person of an INAPPROPRIATE relationship between respiratory WORK and total BODY WORK
What is the perception of breathing akin to?
Sensory modalities (like pain or sound) - the sensation arises at a conscious level.
When a person is aware of their breathing, they make a decision as to whether it is normal or inappropriate. Explain this
Normal would be as a result of exercise whereas breathlessness at rest is deemed inappropriate.
Is ventilatory work mainly inspiratory or expiratory?
Inspiratory
What are the two components that make up ventilatory work?
- Stretching work = elastic work
2. Airflow work = resistive work (friction of air)
What is the difference between restrictive and resistive?
Resistive is the friction caused by air flowing through the airways and is very small (negligible)
Restrictive work is affected by inflammation and fibrosis of the interalveolar septa
What is the difference between restrictive and resistive?
Resistive is the friction caused by air flowing through the airways and is very small (negligible)
Restrictive work is affected by inflammation and fibrosis of the interalveolar septa
What is the total body of work?
The drive (metabolic activity) that are a combination of the multiple stimuli to breathe
What is the total body of work?
The drive (metabolic activity) that are a combination of the multiple stimuli to breathe
What are the two approaches to diagnosing dyspnoea?
Physiological: Increased Load and/or an Increased Drive leads to the shortness of breath
Clinical approach: patients risk factors, presentation and associated features, clinical signs and from this to an organ directed test
What body systems can cause dyspnoea?
Respiratory Cardiac Muscle weakness Metabolic (eg. acidosis) Anaemia Pyschogenic
What are the main respiratory causes of dyspnoea?
- Airways disease (upper vs. lower)
- Alveolar disease
- Pulmonary vascular disease
- Pleural and chest wall disease
- Respiratory muscle disease
What are associated signs that can help narrow the diagnosis to an airways disease?
The presence of wheeze or stridor suggests an obstruction or abnormalities with the airways
(another small sign is the presence of sputum)
What would hint to a clinician COPD or emphysematous disease? How would you confirm this?
Smoking history
CT scanning and Spirometry
