Exam 4: Respiratory L2 Flashcards
Draw the graph that indicates lung volumes AND lung capacities all on one graph
(indicate Vt, IRV, ERV, RV, TLC, FRC, IC, VC)
Explain the following using words:
Tidal Volume
Inspiratory Reserve Volume (IRV)
Expiratory Reserve Volume (ERV)
Residual Volume (RV)
Tidal Volume: the volume inspired or expired during a normal breath (0.5 L)
Inspiratory Reserve Volume: the volume that can be inspired over and above the tidal volume (used during exercise) roughly 3 L
Expiratory Reserve Volume: the volume that can be expired after expiration of a tidal volume roughly 1.2 L
Residual Volume: volume that remains in lungs after maximal expiration (1.2 L)
Explain the following using words:
Inspiratory Capacity
Functional Residual Capacity
Vital Capacity
Total Lung Capacity
Inspiratory Capacity: sum of tidal volume and inspiratory reserve volume (Vt + IRV)
Functional Residual Capacity: sum of ERV and RV (it is essentially the volume remaining in the lungs after a tidal volume is expired)
Vital Capacity: sum of Vt + IRV + ERV (volume of air that can be forcibly expired after maximal inspiration)
Total Lung Capacity: IRV + Vt + ERV + RV (sum of all four lung volumes)
What three things cannot be measured with a spirometer in terms of lung volumes and capacities?
Residual Volume (RV), Functional Residual Capacity (FRC), and Total Lung Capacity (TLC) can NOT be measured with a spirometer
Measurement if RV, FRC, and TLC
What two things can we use to measure them?
Measurement of RV, FRC, and TLC:
Helium dilution vs body plethysmograph:
both use conservation of mass
helium dilution uses concentration and volume
plethysmograph uses pressure and volume
Explain essentially what body plethysmograph does
It measures lung volumes via pressure volume relationships
Explain the clinical importance of helium dilution vs body plethysmography
- Should be equivalent in normal pts
- Helium starts to fail with airway closure (obstructive respiratory disease)
- Plethysmograph can overestimate VL in COPD
- Some evidence that ratio of Helium: Pleth can diagnose severity of COPD (lung volume found via pleth much much higher in severe COPD pt’s than helium)
Draw the pressure volume loop for lungs:
explain all five parts of the graph
Draw the graph and explain the effect of saline inflation on the PV loop
Explain the effects of post-lavage inflation on the PV loop (essentially NO surfactant)
Draw the effects of surface tension and surfactant on the PV loop
Air flows through airways when there is a pressure gradient.
Air flow at a given pressure gradient is determined by:
1.
2.
Air flow at a given pressure gradient is determined by:
pattern of air flow
resistance to airflow by airways
Equation for Reynold’s number
Equation for flow rate
Reynold’s Number:
Re = ((diameter)(velocity)(density))/ (viscosity)
Flow Rate:
V = deltaP pi (r)^4 / 8nL
remember, flow is directly proportional to radius to the fourth power
Explain how flow relates to the increasing cross-sectional area of the airways
Explain airway resistance in the lungs as you go from the conducting zone into the respitatory zone
Airways in parallel
initially, the resistance increses because the CSA stays the same (radius decreases so resistance increases)
Then, as CSA increases more rapidly, there is a rapid decrease in resistance
There is no resistance in the respiratory zone
Draw the graph overlapping the velocity/resistance curve and the CSA curve
Airway CSA and velocity (or resistance) are ____ proportional
Even though the individual airways are getting smaller, the aggregate CSA is ____, thereby ___ resistance
Airway CSA and velocity/resistance are inversely proportional
Even though the individual airways are getting smaller, the aggregate CSA is increasing dramatically, thereby reducting the resistance
Factors Influencing Airway Resistance:
Eqn for Resistance
What are things that increase radius and decrease AWR
What are things that decrease radius and increase AWR
Equation for Resistance: R = 8nL/ pi r^4
Things that increase radius and decrease AWR: increasing lung volume, smooth muscle relaxation, sympathetic stimulation
Things that decrease radius and increase AWR: mucus, edema, smooth muscle contraction, vagal stimulation
Explain the following terms
FVC
FEV1
Ratio of FeV1/FVC
Normal range for that ratio?
How are they used for clinical markers
FVC: forced tital capacity (same as vital capacity)
FEV1: forced expiratory volume in 1 second
Ratio of FEV1/FVC is normally 75%
(so you can normally breathe out about 75% of what you can breathe in within a second)
Generally, if FEV1 is reduced in obstructive
FVC reduced in restrictive
Explain the flow volume loop.
Explain what PEFR, PIFR
Explain what happens to flow rate when you exhale
When you exhale: you initially get a high flow rate and then it tapers off
For expiratory flow rates:
At higher lung volumes it is effort ___
At lower lung volumes it is effort ___ and flow ___
At higher lung volumes, expiratory flow rates is effort dependent
At lower lung volumes, expiratory flow rate is effort independent and flow limited
Explain effort dependent and independent expiratory flow
Explain dynamic airway compression