DSA 2: Lung Volume Flashcards
Residual volume (RV)
Detemined by spirometry?
Residual volume (RV)–>
volume of air that CANNOT be forced out, no matter how hard one tries.
Example- getting the wind knocked out of you.
It cannot be determined by spirometry.
Tidal Volume (VT)
Detemined by spirometry?
the amount of air inspired or expired in one single breath.
Amount will vary under circumstances, but will increase during exercise.
Inspiratory reserve volume (IRV)
-the volume of air breathed ABOVE tidal volume (VT)
Expiratory reserve volume (ERV)
the volume of air that CAN be forced out, in addition the tidal volume.
Does NOT include RV, but requires active expiration.
Vital capacity (VC)
the amount of air that can be maximally INSPIRED followed by maximal expiration
VC= IRV+ VT+ ERV
Influenced by posture, ability of the diaphragm to contract and relax, strength of the respiratory muscles, thoracic wall expansibility, resistance to air flow, elasticity of lungs, dz
Inspiratory capacity (IC)
amount of air that can be maximally inspired after a NORMAL exhale.
IC= VT+ IRV
Functional residual capacity (FRC)
The amount of air that stays in the lungs after a normal expiration
FRC= ERV+ RV
Cannot be determined by spirometry.
This helps to prevent the lungs from collapsing, reduce workload and dilute toxic gases.
Total lung capacity (TLC)
The maximum volume that the lungs can be expanded with the greatest amount of effort
TLC= IC + FRC= VC + RV= ERV + RV + IRV + VT
Cannot be determined by spirometry.
Normal: 5,800- 6,000
How can we determine the FRC?
- Nitrogen-washout technique
- Helium dilution
Nitrogen-washout technique
a person breathes 100% O2 through a one-way valve. All the expired gas is taken and monitored until N2 reaches 0. The total volume of gas expired is determined and multiplied by % of N2 in mixed expired air (80%).
Helium dilution
person inhales a known concentration (C1) of helium (which in insoluble in blood), from a known volume (V1). The change in concentration (C2) lets us determine V2= FRC.
Body plethysmophraphy
Inside an enclosed rigid box, person is asked to breathe against a shutter.
Pressure in lungs change
Pressure in box changes proportionally in opposite direction
Boyle’s Law (P1V1=P2V2)
What helps to prevent the lungs from collapsing, reduce workload and dilute toxic gases.
Functional residiual capacity (FRC)
