Exam 17 - Resp16 - Pulmonary Function Tests

Front 1

3 main components:

1) ... – measures airflow
2) ... – measures volumes and capacities
3) ... – measures gas exchange

Back 1

spiromentry
static lung volumes
diffusion capacity

Front 2

look at slide 10

Back 2

ok

Front 3

A Rapid Approach to Interpreting PFTs: common PFT patterns

Emphysema
-TLC-Hyperinflation and/or air-trapping; can also be normal
-Airflow obstruction
-... diffusing capacity
-FEV1/FVC < ... in COPD

Asthma
-TLC-Hyperinflation and/or air-trapping; can also be normal
-... airflow obstruction (>12% increase in FEV1 after use of bronchodilator)
-Normal or ... diffusing capacity
-FEV1/FVC < ...

Back 3

Reduced
70
Reversible
increased
75

Front 4

A Rapid Approach to Interpreting PFTs: common PFT patterns

Interstitial Lung Disease
-TLC-... or normal; rare cases increased
-Usually no airflow obstruction; rare cases present
-... diffusing capacity

Small Airways Disease
-All values should be normal for TLC, RV, FVC and FEV1
-... % is decreased to <60% of predicted

Back 4

Restriction
Decreased
FEF 25-75

Front 5

Look at the volumes and capacities first

Total Lung Capacity (TLC)
->120% suggests hyperinflation (from ...)
-80-120% is ...
-<80% suggests ...
*80-65% mild
*65-50% moderate
*<50% severe
(this restriction scale can also be used with FVC if TLC is not available)

Residual Volume (RV)
->120% suggests air-trapping (from ...)
RV/TLC >40% suggests air-trapping

Back 5

obstruction
normal
restriction
obstruction

Front 6

Next look at the spirometry values:

Is the FEV1/FVC <75% (... suspected) or <70% (... suspected)?
-If so, obstruction is present

Next determine the degree of obstruction
-Asthma (FEV1)
*>80% mild
*80-60% moderate
*<60% severe
-COPD (FEV1)
*>80 mild
*80-50% moderate
*50-30% severe
*<30% very severe

Finally, examine the diffusing capacity for carbon monoxide (DLCO)
-look at the DL/VA and apply the same criteria listed for restrictive mechanics

Back 6

asthma
COPD

Front 7

look at slide 21

Back 7

ok

Front 8

... Inhalation Challenge Testing:

-Baseline spirometric testing is completed and appears normal
-Patient is subsequently challenged with increasing doses of a drug known to provoke ... (methacholine)
-Goal is to cause a 20% decrease in airflow (FEV1 decrease by 20%) by the fifth dose
-A positive response suggests the presence of ... airways

The earlier it occurs, the more likely it supports diagnosis of asthma. It is very impt in ruling out asthma, not in diagnosing asthma.
If no drop in FEV1, most likely no asthma.

Back 8

Methacholine
bronchoconstriction
hyper-reactive

Front 9

You should look primarily at two values when determining surgical risk-the FEV1 and the PaCO2.
-The more the FEV1 is reduced, the ... the risk for pulmonary complications of surgery.
-Once the patient is below 0.8 or 1.0 liters, the patient is in the ... risk category.

The PaCO2 is also valuable as carbon dioxide retention
-> 45mmHg indicates ... risk of pulmonary complications of surgery.

Back 9

higher
high
increased

Front 10

If FEV1/FVC ratio is < 70%, --> ... (...) disease

Back 10

obstructive (COPD)

Front 11

If TLC is < 80%, --> ... disease

Back 11

restrictive

Front 12

If FEV1/FVC ratio is < 75%, ---> ... (...) disease

Back 12

obstructive (asthma)

Front 13

With interstitial lung disease, you will usually have a ... DL/VA (diffusing capacity)
-keep in mind that interstitial lung disease can be present even w/ a normal ‘corrected’ DL/VA (~10%)

Back 13

low

Front 14

elevated lung volumes (TLC > 120% or hyperinflation; RV > 120% or air-trapping) usually suggest ...

Back 14

emphysema

Front 15

If there is an isolated reduction in the FEF25-75% (< 60%), this suggests ...

Back 15

obstruction in the smaller airways