PFTs Flashcards

1
Q

pulmonary function tests

A

-Categorize the nature and severity of disease
-Follow the progression of disease
-Measure response to therapy
-Define disability
-Pre-op evaluation
-Screening at risk populations
-Monitoring drug toxicity (chemo)

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2
Q

what do lung volumes measure

A

-IRV- inspiratory reserve volume
-Vt- tidal volume - normal breathing
-TLC- total lung capacity
-RV- residual volume - always there
-ERV- expiratory reserve volume - force exhalation
-IC- inspiratory capacity- forced inhalation + tidal

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3
Q

know the chart of diff lung volumes

A

-

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4
Q

spirometry

A

-measures rates at which lung changes volumes during forced breathing maneuvers
-begins with full inhalation and is followed by forced exhalation that rapidly empties lung
-exhalation is continued for as long as possible or until plateau is reached

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5
Q

2 ways to graph spirometry maneuvers

A

-1. volume time curve
-2. flow volume loop (dont need to know as well)

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6
Q

spirometry: volume time curve

A

-simple office based
-measures flow, volumes
-volume vs time
-can determine:
-forced expiratory volume in 1 second (FEV1)
-forced vital capacity (FVC)
-FEV1/FVC

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7
Q

FVC

A

-forced vital capacity
-majority of air comes out in first 1s (<3s)
-total volume of air that can be exhaled forcefully from TLC
-FVC is prolonged in obstructive disease
-measured in liters (L)
-normal 80

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8
Q

FVC ranges

A

> 80% Normal
70-79% Mild reduction
50%-69% Moderate reduction
<50% Severe reduction

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9
Q

FEV1

A

-Forced expiratory volume in 1 second: (FEV1)
-Volume of air forcefully expired from full inflation (TLC) in the first second
-Measured in liters (L)
-measures severity of COPD*
-Normal people can exhale more than 75-80% of their FVC in 1st second -> FEV1/FVC can be utilized to characterize lung disease

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10
Q

FEV1 ranges

A

> 80% Normal
70%-79% Mild obstruction
50-69% Moderate obstruction
<50% Severe obstruction

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11
Q

FEV1/FVC range

A

-normal - 90%
-COPD - 60%
-restrictive- normal ratio (but low FEV1 and FVC)

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12
Q

guiding principles to interpreting pulmonary function tests

A

-1. examine curves
-2. examine FEV1/FVC ratio
-3. examine FEV1 value
-normal curve plateaus at 3s
-obstructive- prolonged plateau (even up to 10s)
-restrictive- shorter (less volume in and out)

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13
Q

normal values are based on

A

-race
-height
-age
-sex

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14
Q

interpreting spirometry results: guidelines

A

-FVC, FEV1, and FEV1/FVC ratio are used
-confident dx with high or low values
-low FEV1/FVC ratio is hallmark of airflow obstruction
-classify severity using FEV1 expressed as % of predicted value
-determine response to bronchodilator therapy to eval reversibility
-spirometry also measures restrictive
-restrictive lung disease requires additional studies**

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15
Q

flow volume loops

A

-shows max expiratory and inspiratory flow volumes curves
-useful to help characterize disease states (obstructive vs restrictive)
-normal- right triangle
-obstructive- depressed curve
-dont need to interpret for test
-restrictive- narrower triangle

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16
Q

obstructive disease

A

-decreased FEV1
-decreased FVC
-decreased FEV1/FVC -> >90% of predicated value is considered normal
-FEV1 much lower than FVC
-FEV1 used to follow severity in COPD

17
Q

bronchodilator response

A

-degree to which FEV1 improves with inhaled bronchodilator
-documents reversible airflow obstruction
-significant response if: FEV1 increases by 12% AND <200 -> fully reversible**
-request if obstructive pattern on spirometry
-reversible - asthma (rather than COPD)
-you dont give beta agonist for restrictive

18
Q

bronchoprovocation

A

-Useful for diagnosis of asthma in the setting of normal pulmonary function tests
-brings on an attack in controlled setting
-Common agents: Methacholine, Histamine, others
-Diagnostic if: ≥20% decrease in FEV1

19
Q

emphysema

A

-floppy airways -> TOO compliant
-bulla
-destruction of alveoli
-low recoil pressure

20
Q

diffusing capacity

A

-alveoli issue
-issue with blood flow to alveoli
-basement membrane between alveoli and capillaries
-DETERMINED BY:
-SA of alveoli
-thickness of alveolar membrane
-volume of blood in capillary bed
-reaction rate of test gas (CO) with Hgb

21
Q

decrease DLCO (diffusing capacity of the lungs for carbon monoxide)

A

-<80% predicted)
-obstructive lung disease (emphysema)
-parenchymal disease (alveolar disease)
-pulmonary vascular disease (PE, PHTN)
-anemia

22
Q

increased DLCO (diffusing capacity of the lungs for carbon monoxide)

A

->120%-140% predicted
-pulmonary hemorrhage
-polycythemia
-left to right shunt

23
Q

residual volume WNL

A

80-120

24
Q

restrictive pattern

A

-decrease FEV1
-decrease FVC
-FEV1/FVC normal or increased
-flow volume curve is steeper- 3L
-high recoil pressure and low compliance

25
Q

spirometry CANNOT measure

A

-TLC
-FRC
-RV

26
Q

TLC and RV in obstructive and restrictive lungs

A

-obstrucitve: HIGH
-TLC > 120% predicted
-RV > 120% predicted
-restrictive: LOW
-TLC < 80% predicted
-RV < 80% predicted