PFT Final UPDATED Exam Questions and
CORRECT Answers
Raw in healthy adults: - CORRECT ANSWER - nose, mouth, upper airway 50%
trachea & bronchi 30%
small airways 20%
Pressure difference in Raw is primarily caused by - CORRECT ANSWER - the friction of
gas molecules in contact w/ the airways
Raw results from - CORRECT ANSWER - frictional changes in the air that flows from the
mouth to the alveoli
Raw is measured by - CORRECT ANSWER - the body box w/ shutter valve "OPEN"
Airflow is related to - CORRECT ANSWER - the pressure gradient
Raw can be expressed as follows: - CORRECT ANSWER - Raw = ∆P (alveoli &
mouth)/Flow
Raw is recorded in - CORRECT ANSWER - cmH2O/L/sec
The forces governing maximal airflow in the lungs are: - CORRECT ANSWER - elastic
recoil & resistance of the airways
Elastic recoil: - CORRECT ANSWER - diseases that alter elasticity of the lung include:
emphysema, pulmonary fibrosis, sarcoidosis
,Resistance of the airways: - CORRECT ANSWER - inflammation, mucus secretions,
bronchospasm, foreign bodies, tumors, and emphysema all cause an increase in resistance
Measurement of Raw in body box: - CORRECT ANSWER - -pt pants w/ shutter OPEN
-as pt pants w/ shutter OPEN, flow is plotted against box pressure as an S-shaped curve.
-a tangent (the slope) is measured from this curve
-pt pants w/ small VT at a rate of 1.5-2.5 bps
Normal Raw loop: - CORRECT ANSWER - tracing shows narrow loop
Small narrow loop: - CORRECT ANSWER - caused by panting frequency too high or
panting volume too small
Wide large loop: - CORRECT ANSWER - caused by panting frequency too low or
panting volume too large
Thermal drift: - CORRECT ANSWER - caused by failure of body box to establish a
constant temp before obtaining panting loops
Fixed airway obstruction: - CORRECT ANSWER - shows a loop flattening on the
inspiratory & expiratory portions of panting loop
Airway resistance (Raw): - CORRECT ANSWER - the pressure diff per unit flow as gas
flows into or out of lungs
Normal values of Raw in adults: - CORRECT ANSWER - 0.6 to 2.4 cmH2O/L/sec
Airway conductance (Gaw): - CORRECT ANSWER - flow generated per unit of pressure
drop across airways
,Airway conductance (Gaw) is the - CORRECT ANSWER - reciprocal of Raw (1/Raw)
(L/sec/cmH2O)
Gaw is recorded in - CORRECT ANSWER - L/sec/cmH2O
Normal values of Gaw in adults: - CORRECT ANSWER - 0.42 to 1.67 L/sec/cmH2O
Specific airway conductance (sGaw) is - CORRECT ANSWER - usually reported bc Gaw
changes with lung volume
sGaw is calculated as - CORRECT ANSWER - Gaw divided by the lung volume (VTG) at
which measurement was made & is recorded in L/sec/cmH2O/L
sGaw values less than 0.15 L/sec/cmH2O/L are - CORRECT ANSWER - consistent w/
airway obstruction
Calculation of sGaw: - CORRECT ANSWER - sGaw = (1/Raw)/LV
Raw measurement technique: - CORRECT ANSWER - -Pt pants w/ small Vt at rate of
1.5-2.5 bps
-small rapid breaths reduce thermal drift
-panting eliminates a # of artifacts related to gas temp from tracing
-panting helps keep glottis open
-panting allows measurements to be made near FRC
Common problems w/ measurement of Raw - CORRECT ANSWER - -thermal drift
-panting too high or low a frequency
-panting too high or low a volume
-leaks at the mouthpiece
, Criteria for acceptability Raw & sGaw - CORRECT ANSWER - -pressure-flow loops
should be closed
-thermal equilibrium should be established
-panting frequency should be 1.5-2.5
-mean of 3 acceptable efforts; within 10% of mean
Raw values > 2.4 are - CORRECT ANSWER - consistent w/ obstruction
sGaw values < 0.15 are - CORRECT ANSWER - consistent w/ obstruction
Raw may be increased 3 times the normal values in an - CORRECT ANSWER - acute
asthma episode
Raw is increased by - CORRECT ANSWER - inflammation, mucus secretion &
bronchospasm
Raw is increased in advanced emphysema bc of - CORRECT ANSWER - airway
narrowing & collapse
sGaw is useful for assessing changes in airway caliber after - CORRECT ANSWER -
bronchodilator therapy or inhalation challenge
Forced oscillation technique measures: - CORRECT ANSWER - Raw in children & others
who can't perform panting maneuver of Raw in body box
Forced oscillation technique is a technique of - CORRECT ANSWER - applying an
oscillation flow of gas to the resp system & measuring the resulting pressure response
CORRECT Answers
Raw in healthy adults: - CORRECT ANSWER - nose, mouth, upper airway 50%
trachea & bronchi 30%
small airways 20%
Pressure difference in Raw is primarily caused by - CORRECT ANSWER - the friction of
gas molecules in contact w/ the airways
Raw results from - CORRECT ANSWER - frictional changes in the air that flows from the
mouth to the alveoli
Raw is measured by - CORRECT ANSWER - the body box w/ shutter valve "OPEN"
Airflow is related to - CORRECT ANSWER - the pressure gradient
Raw can be expressed as follows: - CORRECT ANSWER - Raw = ∆P (alveoli &
mouth)/Flow
Raw is recorded in - CORRECT ANSWER - cmH2O/L/sec
The forces governing maximal airflow in the lungs are: - CORRECT ANSWER - elastic
recoil & resistance of the airways
Elastic recoil: - CORRECT ANSWER - diseases that alter elasticity of the lung include:
emphysema, pulmonary fibrosis, sarcoidosis
,Resistance of the airways: - CORRECT ANSWER - inflammation, mucus secretions,
bronchospasm, foreign bodies, tumors, and emphysema all cause an increase in resistance
Measurement of Raw in body box: - CORRECT ANSWER - -pt pants w/ shutter OPEN
-as pt pants w/ shutter OPEN, flow is plotted against box pressure as an S-shaped curve.
-a tangent (the slope) is measured from this curve
-pt pants w/ small VT at a rate of 1.5-2.5 bps
Normal Raw loop: - CORRECT ANSWER - tracing shows narrow loop
Small narrow loop: - CORRECT ANSWER - caused by panting frequency too high or
panting volume too small
Wide large loop: - CORRECT ANSWER - caused by panting frequency too low or
panting volume too large
Thermal drift: - CORRECT ANSWER - caused by failure of body box to establish a
constant temp before obtaining panting loops
Fixed airway obstruction: - CORRECT ANSWER - shows a loop flattening on the
inspiratory & expiratory portions of panting loop
Airway resistance (Raw): - CORRECT ANSWER - the pressure diff per unit flow as gas
flows into or out of lungs
Normal values of Raw in adults: - CORRECT ANSWER - 0.6 to 2.4 cmH2O/L/sec
Airway conductance (Gaw): - CORRECT ANSWER - flow generated per unit of pressure
drop across airways
,Airway conductance (Gaw) is the - CORRECT ANSWER - reciprocal of Raw (1/Raw)
(L/sec/cmH2O)
Gaw is recorded in - CORRECT ANSWER - L/sec/cmH2O
Normal values of Gaw in adults: - CORRECT ANSWER - 0.42 to 1.67 L/sec/cmH2O
Specific airway conductance (sGaw) is - CORRECT ANSWER - usually reported bc Gaw
changes with lung volume
sGaw is calculated as - CORRECT ANSWER - Gaw divided by the lung volume (VTG) at
which measurement was made & is recorded in L/sec/cmH2O/L
sGaw values less than 0.15 L/sec/cmH2O/L are - CORRECT ANSWER - consistent w/
airway obstruction
Calculation of sGaw: - CORRECT ANSWER - sGaw = (1/Raw)/LV
Raw measurement technique: - CORRECT ANSWER - -Pt pants w/ small Vt at rate of
1.5-2.5 bps
-small rapid breaths reduce thermal drift
-panting eliminates a # of artifacts related to gas temp from tracing
-panting helps keep glottis open
-panting allows measurements to be made near FRC
Common problems w/ measurement of Raw - CORRECT ANSWER - -thermal drift
-panting too high or low a frequency
-panting too high or low a volume
-leaks at the mouthpiece
, Criteria for acceptability Raw & sGaw - CORRECT ANSWER - -pressure-flow loops
should be closed
-thermal equilibrium should be established
-panting frequency should be 1.5-2.5
-mean of 3 acceptable efforts; within 10% of mean
Raw values > 2.4 are - CORRECT ANSWER - consistent w/ obstruction
sGaw values < 0.15 are - CORRECT ANSWER - consistent w/ obstruction
Raw may be increased 3 times the normal values in an - CORRECT ANSWER - acute
asthma episode
Raw is increased by - CORRECT ANSWER - inflammation, mucus secretion &
bronchospasm
Raw is increased in advanced emphysema bc of - CORRECT ANSWER - airway
narrowing & collapse
sGaw is useful for assessing changes in airway caliber after - CORRECT ANSWER -
bronchodilator therapy or inhalation challenge
Forced oscillation technique measures: - CORRECT ANSWER - Raw in children & others
who can't perform panting maneuver of Raw in body box
Forced oscillation technique is a technique of - CORRECT ANSWER - applying an
oscillation flow of gas to the resp system & measuring the resulting pressure response
