General Principles of Lung Physiology Flashcards
Define tidal volume
Volume that enters and leaves the lung with each breath
Quiet breathing
What is the average tidal volume (L)
0.5
What does tidal volume change with
Pattern of breathing e.g. shallow breaths vs deep breaths
Increases with pregnancy
Define inspiratory reserve volume
Extra volume that can be inspired above tidal volume, from normal to quiet expiration to maximum inspiration
What is the average inspiratory volume (L)
2.5
What does inspiratory volume rely on
Muscle strength
Lung compliance
Normal starting point
Define expiratory reserve volume
Extra volume that can be expired below tidal volume, from normal quiet expiration to maximum expiration
What is the average volume of expiratory reserve volume (L)
1.5 L
What does expiratory reserve volume rely on
Muscle strength
Low airway resistance
What reduces expiratory reserve volume
Pregnancy
Obesity
Severe obstruction
Define residual volume/reserve volume
Volume remaining after maximum expiration
What is the average volume of residual volume/reserve volume (L)
1.5
What can residual volume/reserve volume not be measured by
Spirometry
Define capacities
Composed of two of more lung volumes
These are fixed and do not change with patterns of breathing
Define vital capacity/forced vital capacity
Volume that can be exhaled after maximum inspiration
Maximum inspiration to maximum expiration
How would you calculate vital capacity/forced vital capacity
Inspiratory reserve volume +
Tidal volume +
Expiratory reserve volume
What is the average volume of vital capacity/forced vital capacity
4.5 L
Define functional residual capacity
Volume remaining after quiet expiration
How do you calculate functional residual capacity
Expiratory reserve volume +
Residual volume
What is the average volume of functional residual capacity
3 L
What is average functional residual capacity affected by
Height (has the greatest influence)
Gender
Posture
Changes in lung compliance
Define inspiratory capacity
Volume breathed in from quiet expiration to maximum inspiration
How would you calculate inspiratory capacity
Tidal Volume +
Inspiratory reserve volume
What is the average volume of inspiratory capacity (L)
3L
Define total lung capacity
Volume of air in lungs after maximum inspiration
How would you calculate total lung capacity
Sum of all volumes
Define restriction
< 80% of predicted total lung capacity
What is the average volume of total lung capacity
6 L
Define hyperinflation
> 120% of predicted total lung capacity
