Respiratory Cycle + Lung Volumes DSA Flashcards
What is the general rule for one letter abbreviations?
capital letters = air
lower letters = blood
What does v with a line above it mean?
mixed venous (blood from all the organs/tissues mixed together)
What does F stand for?
fractional concentration of gas (would specify what gas you are referring to)
What is the abbreviation for arterial?
a
How do you calculate munite ventilation?
V(dot) = Vt * f
(tidal volume times respiratory rate)
What is the nitrogen-washout technique?
determines FRC
person breaths 100% O2 through one-way valve –> all expired gas collected until N2 reaches 0
total vol of all gas expired is measured and multiplied by % of N2 on mixed expired air (80%)
What is the abbreviation for blood flow?
Q
How is alveolar ventilation calculated/ what is it?
V(dot)A = (VT - VDS)*f
What is ERV?
expiratory reserve volume
volume of air that can be forced out in addition to tidal volume
*doesn’t include residual volume
*requires activation of expiratory muscles
What does a positive transpulmonary pressure mean?
the lungs are “open” or partially inflated
What is IC?
inspiratory capacity
capacity of air that can be maximally inspired following a normal exhale
IC = Vt + IRV
What is residual volume?
RV
volume of air that cannot be forced out, no matter how hard one tries
cannot be determined by spirometry
What is the abbreviation for alveolar?
A
What is the function of FRC?
helps prevent collapse of lungs, reduces workload, dilutes toxic inhaled gases
What is physiologic dead space?
anatomic dead space plus alveolar dead space
What is FRC?
functional residual capacity
amount of air that remains in the lungs following a normal expiration
FRC = ERV+RV
What is inspiratory reserve volume?
IRV
volume of air breathed above tidal volume
What is intrapleural pressure at rest?
-5 cm H2O
What are the abbreviations for atmospheric pressure?
PATM or PB
What is VC?
vital capacity
amount of air that can be maximally inspired following a max expiration
VC = IRV + VT + ERV
As the volume in the thorax goes up, what happens to the intrapleural pressure?
goes down!
(think PV=nRT)
What is Helium dilution?
used to measure FRC
inhale known concentration of helium (insoluble in blood) from known volume -> change in concentration allows for determination of FRC
What is alveolar volume?
amount of air that actually gets to the alveoli and participates in gas exchange
VA = Vt - VDS
What is normal atmospheric pressure?
0 cm H20
What is transpulmonary pressure?
Pressure “across” the lungs
PALV -PIP
What is Vdot?
airflow or volume per unit time
What is body plethysmography?
used to measure FRC
enclosed in box –> breath against shutter –> pressure in lungs change –> pressure in box changes proportionally
At the end of expiration, what muscles are activated to hold the thorax at volume?
none! no effort is required to hold the thorax at rest
What is the rough estimate for anatomic dead space?
VDS
volume in mL = weight in lbs
What is alveolar dead space conceptually?
alveoli that are getting air, but not blood
