ch 4

Question 1

what are the primary purpose of performing pulmonary function test (pft)

Answer 1

-evaluate pulmonary causes of dyspnea
-differentiate b/w obstructive & restrictive pulmonary disorders
-assess severity of pathophysiologic impairment
-follow the course of particular disease
-evaluate the effectiveness of therapy
-assess the patients preoperative status

Question 2

list the 4 major categories of PFTs

Answer 2

-lung volumes & lung capacities
-forced expiratory flow rate & volume measurements
-pulmonary diffusion capacity measurements
-test of respiratory muscle strength

Question 3

why are PFTs useful for evaluating preoperative risk

Answer 3

identify pt with higher surgical risk due to reduced pulmonary reserve

Question 4

describe tidal volume (VT)

Answer 4

normal quiet breathing

Question 5

describe inspiratory reserve volume (IRV)

Answer 5

extra air inhaled after normal breath (VT)

Question 6

expiratory reserve volume (ERV)

Answer 6

extra air forced out after normal breathing
*think of blowing out candle

Question 7

residual volume (RV)

Answer 7

amount of air remaining in lungs after forced exhalation *stays in lungs doesn’t empty

Question 8

how is vital capacity calculated

Answer 8

IRV + VT + ERV=VC

Question 9

what is the difference between IC and FRC

Answer 9

ic= IRC+VT, total amount of air that can be inhaled after normal exhalation

FRC=ERV+RV, lung volume at rest after a normal exhalation

Question 10

which lung volume is alway present in the lungs even after maximum exhalation

Answer 10

residual volume

Question 11

describe how lung compliance changes in restrictive lung disorders

Answer 11

decrease lung compliance

Question 12

which lung volumes are reduced in restrictive disorders

Answer 12

all lung volumes
*VT,IRV,ERV,RV

capacities as well
*VC,IC,FRC,TLC

Question 13

what is air trapping and how does it affect lung volume in obstructive disorders?

Answer 13

air trapping is retention of air on exhalation–>increase RV and FRC

Question 14

which lung volume is typically increased in obstructive lung disorders

Answer 14

RV, due to air trapping

Question 15

give examples of restrictive lung diseases

Answer 15

-pulmonary fibrosis
-tuberculosis
-kyphoscoliosis

Question 16

give examples of obstructive lung diseases

Answer 16

-emphysema
-chronic bronchitis
-asthma

Question 17

what is the purpose of the Forced vital capacity maneuver

Answer 17

total volume forcefully exhaled after full inspiration

Question 18

define FEV1

Answer 18

flow expired in 1 second
-indicator of how quickly airways can clear air

*if low=obstruction in airways

Question 19

how is the FEV1/FVC ratio used to differentiate between obstructive and restrictive disorders?

Answer 19

obstructive: FEV1/FVC <70%

restrictive: FEV1/FVC >70%

Question 20

what does an FEV1/FVC ratio of <70% indicate?

Answer 20

obstructive lung disorder

Question 21

what does a FEV1/FVC ratio of >70% but reduced lung volumes indicate?

Answer 21

restrictive disorder

Question 22

what is the shape of the flow-volume loop in an obstructive lung disease?

Answer 22

*flow problem
concave appearance or scooped out of expiratory limb

Question 23

how does the flow volume loop differ in restrictive lung disease?

Answer 23

*volume problem
smaller, skinner loop

Question 24

why is the loop smaller in restrictive diseases

Answer 24

pt have a volume problem ( not enough air getting into the lungs) reduced lung volume

Question 25

what does the DLCO test measure and why is carbon monoxide used

Answer 25

DLCO measures the diffusion capacity of CO that moves across the alveolar capillary membrane. CO is used because it has higher diffusion rate than others (favorite )

Question 26

what is the normal DLCO range in healthy adults

Answer 26

25-30mL/min/mmHg

Question 27

which conditions decrease DLCO and why?

Answer 27

-emphysema -pulmonary fibrosis -sarcoidosis -edema -asbestosis *they reduce surface area or thicken membrane

Question 28

why is DLCO often normal or elevated in asthma

Answer 28

-asthma increase DLCO due to higher pulmonary blood flow and normal alveolar integrity

Question 29

what is Maximum inspiratory pressure (MIP)?

Answer 29

maximum inspiratory pressure a pt can generate against closed airway -measures the inspiratory muscle strength

Question 30

what is the critical MIP value that suggest a need for ventilatory support?

Answer 30

-20cmH20 or less negative ex.(-15,-19, closer to zero)

Question 31

what is normal value for MIP

Answer 31

normal -30cmH20 or more negative ex (-40,-50)

Question 32

what is maximum expiratory pressure (MEP) and what does it measure

Answer 32

maximum positive pressure during expiration -measures strength of expiratory muscles.

Question 33

what is the critical MEP value that suggests a need for ventilatory support?

Answer 33

40cmH2O or less

Question 34

how do low MIP and MEP values affect a pt ability to breathe and cough

Answer 34

weak MIP-difficulty inspiring weak MEP-ineffective cough secretion clearance

Question 35

a pt has FEV1/FVC of 55%, which category of lung disease is this most likely?

Answer 35

obstructive lung disorder

Question 36

a patient has a normal FEV1/FVC ratio but TLC and VC are 50% of predicted, which type of lung disease is this?

Answer 36

restrictive disease *normal FEV1/FVC=70% however when lung volumes /capacities are decrease it indicates restrictive

Question 37

what does a concave appearance of the expiratory limb on a flow-volume loop indicate?

Answer 37

obstructive lung disorder

Question 38

pt has MEP of 28cmH2O, what complication might they be at risk for?

Answer 38

28 is <40mmH20, so indicate need for ventilatory support

Question 39

a pt with pulmonary fibrosis has DLCO of 15mL/min/mmHg,what does this mean about their diffusion capacity?

Answer 39

poor perfusion

Question 40

added card* what is FEV1/FVC

Answer 40

-forced expiration in 1 sec/forced vital capacity -expressed in % -determines if pt has obstructive or restrictive disease

Question 41

added card* FEV1/FVC ratio obstructive & restrictive

Answer 41

obstructive: *FEV1/FVC decreased *,70% restrictive: *FEV1/FVC is normal * >70% but volumes are lower than predicted

Question 42

added card* Total lung capacity (TLC)

Answer 42

TLC=IC+ERV+RV maximal amount of air that the lungs can accommodate