Ventilation and Compliance Flashcards
What is anatomical dead space?
Volume of gas occupied by the conducting airways and this gas is not available for gas exchange - 150 ml
What is the inspiratory reserve volume? (IRV)
The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration
3000ml
What is the volume of air at the start of normal inspiration?
2300
What is tidal volume?
The 500ml that we breath in with every breath at rest
What is residual volume?
The volume of air we can’t expel from our lungs - holds alveoli open (even after maximal respiration) - 1200 ml
What is the functional residual capacity?
Expiratory reserve volume + residual volume.
What is a capacity?
Two or more volumes added together
What is vital capacity?
Tidal volume + inspiratory reserve volume + expiratory reserve volume
What is the maximum volume of air a pair of lungs can hold?
5800ml
What is pulmonary (Minute) ventilation?
Total air movement into/out of lungs (relatively insignificant in functional terms)
What is Alveolar ventilation ?
Fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant!)
DIAGRAM
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Will someone who is anxious have a higher or lower tidal volume?
Lower but faster respiratory rate
How do you calculate air to alveoli?
Tidal - dead space
What is the main factor that affects the aeriolar ventilation?
The depth of the breadth, rather than the respiratory rate, because of the influence of the dead space volume.
What is hyperventilation?
Increased ventilation - concerns depth and not frequency of breathing
Relaxed is hyperventilating
What is partial pressure?
Definition:The pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture
What measurement of pressure do clinicians use?
Kilopascals (kPa)
What is another measurement of pressure that isn’t kilopascals?
Millimetres mercury mmHg
What is atmospheric pressure?
760mmHg (101kPa)
What is normal alveolar ventilation?
4.2 litres/minute
Why is the alveolar partial pressure less than atmospheric partial pressure?
Inefficiency of breathing - dead space dilutes the amount of oxygen
Residual volume - dilutes the amount of oxygen
Water is added - displaces some of the oxygen
What is the partial pressure of the atmosphere?
160 mmHg
What is expiratory reserve volume?
The maximum volume of air which can be expelled from the lungs at the end of a normal expiration.
What is the total lung capacity?
The vital capacity plus the residual volume
What is the inspiratory capacity?
Tidal volume + inspiratory reserve volume.
What does FEV1 stand for?
Forced Expired Volume in 1 second
what does FEV1:FVC stand for?
Fraction of Forced Vital Capacity expired in 1 second
What is the fluctuation of PO2 and PCO2 like under normal resting conditions?
PO2 and PCO2 remain fairly constant
What happens to PO2 and PCO2 during hyper-ventilation (increased alveolar ventilation)?
PO2 rises to about 120 mm Hg and PCO2 falls to about 20 mmHg
What happens to PO2 and PCO2 during hypo-ventilation (decreased alveolar ventilation)?
PO2 falls to 30 mmHg and PCO2 rises to 100 mmHg
