Ventilation Flashcards
What is Pulmonary ventilation?
The volume of air inhaled per minute (minute ventilation/ (VE) )
What is Alveolar ventilation?
The volume of air reaching the respiratory zone per minute
Subtract physiological dead space from tidal volume
What are the four lung volumes?
Inspiratory reserve volume
Tidal volume
Expiratory reserve volume
Residual volume
(no overlap)
What are the four lung capacities?
Inspiratory capacity (tidal + Inspiratory reserve)
Vital Capacity (all but residual volume)
Functional residual capacity (Residual volume + Expiratory reserve volume)
Total lung capacity
What are the factors affecting lung volumes and capacities?
Body size (height and shape - but obesity does not increase size of lungs), sex (males larger), disease (lung muscle/tissue disorders), age (decrease with age), fitness (innate»_space; training)
How do rate of exhalation and Forced Vital capacity change in restrictive airway disease?
Normal rate of exhalation
Reduced FVC
What is FVC?
Forced vital capacity
How do rate of exhalation and Forced Vital capacity change in obstructive airway disease?
Reduced rate of exhalation
Markedly reduced FVC
How do lung volumes change in Obstructive disease?
Increased residual volume, with reduced IRV, ERV and TV
How do lung volumes change in Restrictive disease?
Decreased IRV, ERV, RV and TV
Name two obstructive lung diseases:
COPD and Asthma
Name four restrictive lung diseases:
Lung fibrosis, Interstitial lung disease, obesity and neuromuscular disease
What is anatomical dead space?
Capacity of the airways incapable of undertaking gas exchange; usually the conducting zone - the first 16 generations of airways (150ml) - e.g. Nose, pharynx, larynx, trachea, bronchi and bronchioles
What is Alveolar dead space?
Capacity of the airways that should be able to undertake gas exchange but cannot (e.g. hypoperfused alveoli); usually the non-perfused parenchyma, which should be 0ml in adults
What is physiological dead space?
Sum of the alveolar and anatomical dead space; i.e. Should be 150ml in adults
What can increase and decrease dead space?
Increase: snorkelling / anaesthetic circuits
Decrease: tracheostomy / cricothyrotomy
Describe the Ventilation and perfusion in the lung apex:
Alveoli are stretched by gravity due to a greater transmural pressure, so need a greater pressure to inflate (less compliant and perform less ventilation); simultaneously, blood is pulled downwards, achieving a lower intravascular pressure, causing reduced perfusion
Describe the Ventilation and Perfusion in the lung base:
Alveoli are squashed and so can inflate more, performing more ventilation; simultaneously blood is pulled downwards to produce a higher intravascular pressure, increasing perfusion of the parenchyma
What is Ventilation Perfusion Matching?
Perfusion and Ventilation both increase towards lung base, but perfusion does so at a greater rate
What is wasted ventilation?
Occurs at lung apex bc perfusion cannot meet demands of ventilation supplied
What is wasted perfusion?
Ocurs at base bc ventilation cannot meet demands of perfusion supplied
What is the Ventilation-Perfusion ratio?
V/Q ratio would be 1 if matched, but gravity means changes regionally (calculated as alveolar ventilation/cardiac output) - averages approx. 0.84 in a healthy lung
