B4-023 Mechanics of Ventilation Flashcards
inspiration is [active/passive]
active
expiration is [active/passive]
passive
lungs intrinsic tendency to deflate following inhalation
elastic recoil
PPL at rest is always
-5
when no airflow, PA is always
0
transpulmonary pressure equation
PA-PPL
pressure of gas is […] related to volume
inversely
increasing the lung volume […] pressure
decreases
air can enter lung
decreasing lung volume […] pressure
increases
air exits
normal atmospheric pressure adjusts to […] cm H20 for ventilation equations
0 cm H2O
at rest with no inspiration, atmospheric and alveolar pressures are
zero
intrapleural pressure is […] than atmospheric pressure
less
less than 0
at rest, intrapleural pressure is
-5 cm H2O
during inspiration, intrapleural pressure decreases to
-8 cm H2O
as the lungs increase in size, alveolar pressure
decreases
near the end of inspiration, alveolar pressure is
-1 cm H2O
alveoli increase in size, causes air to enter lungs
what is happening in the respiratory cycle mid inspiration?
discuss volume, alveolar pressure, PPL, air flow
volume: increasing
alveolar pressure: decreasing
PPL: decreasing
air flowing into lungs
what is happening in the respiratory cycle at end of inspiration?
discuss volume, alveolar pressure, PPL, air flow
volume: has reached tidal volume
alveolar pressure: zero
PPL: -8 cm H2O
air flow has ceased
as lungs increase in size, alveolar pressure
decreases
pressure needed to keep lungs inflated
TPP
at rest, PTP is
5 cm H2O
relationship between PTP and PPL in static conditions
PTP= -PPL
when given in a problem, FRC means
at rest
decreasing volume during expiration returns PPL to
-5 cm H2O
during expiration, alveolar pressure increases to
+1 cm H2O
what is happening in the respiratory cycle mid expiration?
discuss volume, alveolar pressure, PPL, air flow
volume: decreasing
PA: rises
PPL: rising
air exits lung
what is happening in the respiratory cycle at end of expiration?
discuss volume, alveolar pressure, PPL, air flow
volume: return to resting
PA: zero
PPL: -5 cm H2O
air has exited lungs
pressure balance at the end of expiration
FRC
the amount of air inspired or expired in a single breath
tidal volume
normal resting tidal volume
500 mL
volume of air breathed above tidal volume
inspiratory reserve volume
IRV
volume of air that can be forced out in addition to tidal volume
expiratory reserve volume
ERV
volume of air that cannot be forced out, no matter how hard one tries
residual volume
RV
amount of air that can be inspired following normal expiration
vital capacity (VC)
VC equation
IRV+TV+ERV
amount of air in the lungs following normal exhalation
functional reserve capacity
FRC
FRC equation
ERV + RV
maximal volume to which lungs can be expanded with greatest effort
total lung capacity
TLC
TLC equations
3
- IC+FRC
- VC+RV
- ERV+RV+IRV+VT
change in volume of lungs for a given change in PTP
compliance
resistance of respiratory tract to airflow during expiration
resistance
- done as rapidly as possible
- provides and indirect measurement of airway resistance
FVC
forced vital capacity
volume that can be exhaled in first second of FVC maneuver
FEV1
forced expiratory volume
normal FEV1/FVC is
.7-.8
pulmonary compliance equation
PTP is equal to
PA- PPL
decreased volume corresponds with […] PTP
decreased
increased volume corresponds with […] PTP
increased
at rest, PTP is equal and opposite to
PPL
compliance is […] at high volumes
low
compliance is […] at low lung volume
high
increased compliance:
inspiration is […]
expiration is […]
easy
hard
decreased compliance:
inspiration is […]
expiration is […]
hard
easy
resistance is highest in
extrapulmonary airways
nose
smallest airways have the least amount of resistance because they have a high
cross sectional area
at FRC when there is no airflow
PPL=
PALV=
PTP=
PPL= -5
PALV= 0
PTP= +5
during inspiration, PALV
decreases to -1
in order for the lungs to be inflated, PTP has to be
positive
the amount of air that remains in the lungs following normal expiration and prevents collapse
FRC
if a lower PPL is needed to maintain the same lung volume, this represents a […] in compliance
decrease
strong indicator of airway resistance
FEV1/FVC
normal resistance in healthy individuals
0.7-0.8
decreased FEV1/FVC
increased RV
indicates
severe airway resistance
