Respiratory Flashcards
(26 cards)
tidal volume (TV)
volume inspired or expired with each normal breath (or VT)
inspiratory reserve volume (IRV)
- volume that can be inspired over and above the tidal volume
- used in exercise
expiratory reserve volume (ERV)
the volume that can be expired after the expiration of the TV
Residual volume (RV)
- the volume that remains in the lungs after maximal expiration
- cannot be measured by spiro
Dead space is
anatomic plus physiologic
anatomic dead space
- volume in conducting airways
2. normally 150mL
physiologic dead space
- functional measurement
2. volume of lungs that does not participates in gas exchange
minute ventilation is expressed as
VT x breaths/min
alveolar ventilation
VA = (VT - VD) x Breaths/min
inspiratory capacity
Inspiratory capacity = Tv + IRV
Functional residual capacity (FRC)
- FRC = ERV + RV
- volume remaining in the lungs after a tidal volume is expired
- includes RV, so it cannot be measured by spiro
VC: vital capacity is
VC = TV + IRV + ERV
the volume of air that can be forcibly expired after maximal inspiration
Total lung capacity (TLC)
- sum of all 4 lung volumes
- volume in the lungs after maximal inspiration
- includes RV, so it cannot be measured by spirometry
FEV1 is normally
80%
it is the volume of air that can be expired in the first second of a forced maximal inspiration
FEV1/FVC in restrictive disease
increased
FEV1/FVC in obstructive disease
ratio in decreased
muscle of inspiration
- diaphragm
- external intercostals
- accessory muscles
muscles of expiration
expiration is normally passive
forced: abdominal muscles or internal intercostal muscles
compliance is
- the distensibility of lungs and chest wall
- inversely proportional to elastace
- is the slope of the pressure volume curve
- is the change in volume for given change in pressure
- C = V/P
transmural pressure is
alveolar pressure minus intrapleural pressure
when the pressure outside of the lungs is negative,
the lungs expand and LV increases
when the pressure outside of the lungs is positive,
the lungs collapse and LV decreases
hysteresis is
inflation of the lungs follows a different curve than deflation
this is due to the need to overcome surface tension forces when inflating the lungs
when is compliance the lowest and highest?
the lowest at high expanding pressures.,
the highest at mid ranges of pressure