Pulmonary FunctionPulmonary Function

David Zanghi M.S., MBA, ATC/L, CSCSDavid Zanghi M.S., MBA, ATC/L, CSCS

Purpose of Pulmonary Function Testing

Purpose of Pulmonary Function Testing

Pulmonary Function Testing has Pulmonary Function Testing has been a major step forward in been a major step forward in assessing the functional status of the assessing the functional status of the lungs.lungs.

How much air volume can be moved How much air volume can be moved in and out of the lungs - how large in and out of the lungs - how large the lungs are for this patient.the lungs are for this patient.

How fast the air in the lungs can be How fast the air in the lungs can be moved in and out - a question about moved in and out - a question about how open the lungs are moment to how open the lungs are moment to moment.moment.

How stiff are the lungs and chest How stiff are the lungs and chest wall - a question about lung wall - a question about lung compliance compliance

The diffusion characteristics of the The diffusion characteristics of the alveolar membrane through which alveolar membrane through which gases must move (determined by gases must move (determined by special tests). special tests).

How the lungs respond to chest How the lungs respond to chest physical therapy procedures - it will physical therapy procedures - it will be important to have an admissions be important to have an admissions PFT and a discharge PFT PFT and a discharge PFT performed.performed.

Uses for PFTsUses for PFTs

Screening for the presence of Screening for the presence of obstructive and restrictive diseases obstructive and restrictive diseases

Uses cont’dUses cont’d

Evaluating the patient prior to Evaluating the patient prior to surgerysurgery : :

a. are older than 60-65 years of agea. are older than 60-65 years of age

b. are known to have pulmonary diseaseb. are known to have pulmonary disease

c. are obesec. are obese

d. have a hx of smoking, cough, etc.d. have a hx of smoking, cough, etc.

Uses cont’dUses cont’d

e. will be under anesthesia for a lengthy e. will be under anesthesia for a lengthy period of time period of time

f. are undergoing an abdominal or a f. are undergoing an abdominal or a thoracic operationthoracic operation

Note : A vital capacity is an important Note : A vital capacity is an important preoperative assessment tool. Significantpreoperative assessment tool. Significant

reductions in vital capacity (less than 20 reductions in vital capacity (less than 20 cc/Kg of ideal body weight) indicates that the cc/Kg of ideal body weight) indicates that the patient is at a higher risk for postoperative patient is at a higher risk for postoperative respiratory complications. This is because respiratory complications. This is because vital capacity reflects the patient's ability to vital capacity reflects the patient's ability to take a deep breath, to cough, & to clear the take a deep breath, to cough, & to clear the airways of excess secretions. airways of excess secretions.

Uses cont’dUses cont’d

Evaluating the patient's condition for Evaluating the patient's condition for weaning from a ventilator.weaning from a ventilator. If the patient If the patient on a ventilator can demonstrate a vital on a ventilator can demonstrate a vital capacity (VC) of 10 - 15 ml/Kg of body capacity (VC) of 10 - 15 ml/Kg of body weight, it is generally thought that there weight, it is generally thought that there is enough ventilatory reserve to permit is enough ventilatory reserve to permit (try) weaning & extubation(try) weaning & extubation..

Uses cont’dUses cont’d

Documenting the progression of Documenting the progression of pulmonary disease - restrictive or pulmonary disease - restrictive or obstructive obstructive

Documenting the effectiveness of Documenting the effectiveness of therapeutic interventionstherapeutic interventions

Performance of the PFTPerformance of the PFT Patient Instructions :Patient Instructions :

““Take a deep breath in”Take a deep breath in”““Place the mouthpiece in your mouth”Place the mouthpiece in your mouth”““Create a good lip seal”Create a good lip seal”““Blow out all of the air in your lungs”Blow out all of the air in your lungs”““Blow out the air as fast as you can”Blow out the air as fast as you can”““Keep blowing until I say stop”Keep blowing until I say stop”

When three PFTs are within When three PFTs are within < < 5% 5% variance between the tests, then the variance between the tests, then the testing is over.testing is over.

Important Lung Volumesand Capacities

Important Lung Volumesand Capacities

Forced Vital Capacity (FVC)Forced Vital Capacity (FVC)

Forced vital capacity is the largest Forced vital capacity is the largest volume that can be forcibly exhaled volume that can be forcibly exhaled from the lungs after a profoundly from the lungs after a profoundly deep inhalation.deep inhalation.

FVC is a major marker for FVC is a major marker for obstructive lung disease.obstructive lung disease.

If FVC is low or near normal but If FVC is low or near normal but takes a long time to exhale, takes a long time to exhale, obstructive disease should be obstructive disease should be expected.expected.

Forced Expiratory Volume in One Forced Expiratory Volume in One Second (FEV1)Second (FEV1)

FEV1 is the volume of air that can be FEV1 is the volume of air that can be forcibly exhaled in the first second of a forcibly exhaled in the first second of a FVC maneuver.FVC maneuver.

FEV1 is a major marker for FEV1 is a major marker for obstructive disease.obstructive disease.

If FEV1 is small it is a sign that If FEV1 is small it is a sign that either the volume of air in the lungs either the volume of air in the lungs is small or it is difficult to blow out.is small or it is difficult to blow out.

FEV1/FVC - FEV1 Percent (FEV1%)FEV1/FVC - FEV1 Percent (FEV1%)

This number is the ratio of FEV1 to This number is the ratio of FEV1 to FVC - it indicates what percentage ofFVC - it indicates what percentage of

the total FVC was expelled from the the total FVC was expelled from the lungs during the first second of forced lungs during the first second of forced exhalation.exhalation.

FEV1% is a very important number in FEV1% is a very important number in determining the presence of restrictive determining the presence of restrictive or obstructive disease. If FEV1% is or obstructive disease. If FEV1% is 88% - 100%, it indicates the presence 88% - 100%, it indicates the presence of restrictive disease. If this number is of restrictive disease. If this number is 69% or lower, then the presence of 69% or lower, then the presence of obstructive disease must be expected.obstructive disease must be expected.

FEV3 - This is the amount of air that FEV3 - This is the amount of air that can be blown out of the lungs on can be blown out of the lungs on exhalation in three seconds. In most exhalation in three seconds. In most people, FEV3 maybe very close to the people, FEV3 maybe very close to the actual value of FVC.actual value of FVC.

PEFR - Peak Expiratory Flow RatePEFR - Peak Expiratory Flow Rate This is the maximum flow rate This is the maximum flow rate achieved by the patient during the achieved by the patient during the forced vital capacity maneuver. It forced vital capacity maneuver. It can either be measured in L/sec or can either be measured in L/sec or L/minL/min

PEFR is a useful measure to see if a PEFR is a useful measure to see if a bronchodilatory treatment is improving bronchodilatory treatment is improving obstruction as seen in asthma where obstruction as seen in asthma where there is lots of bronchoconstriction.there is lots of bronchoconstriction.

Forced Expiratory Flow 25% - 75%Forced Expiratory Flow 25% - 75%

This measurement describes the This measurement describes the amount of air expelled from the amount of air expelled from the lungs during the middle half of the lungs during the middle half of the forced vital capacity test. forced vital capacity test.

Many physicians like to look at Many physicians like to look at FEF25%-75% because it is an FEF25%-75% because it is an indicator of obstructive disease. indicator of obstructive disease.

Obstructive DiseasesObstructive Diseases

EmphysemaEmphysema BronchitisBronchitis BronchiectasisBronchiectasis AsthmaAsthma

How Do I Determine TheExtent Of Lung Disease ?How Do I Determine TheExtent Of Lung Disease ?

How do I determine if the patient How do I determine if the patient has mild, moderate or severe lung has mild, moderate or severe lung disease ?disease ?

Normal PFT Outcomes - > 85 % of Normal PFT Outcomes - > 85 % of predicted values predicted values

Mild Disease - > 65 % but < 85 % of Mild Disease - > 65 % but < 85 % of predicted values predicted values

Moderate Disease - > 50 % but < 65 Moderate Disease - > 50 % but < 65 % of predicted values % of predicted values

Severe Disease - < 50Severe Disease - < 50 % of predicted % of predicted values values

Reversible Lung DiseaseReversible Lung Disease

If 2 or more of the PFT variables If 2 or more of the PFT variables change after a bronchodilator change after a bronchodilator treatment, then the patient has treatment, then the patient has reversible disease.reversible disease.

What is Acceptible Change ?What is Acceptible Change ?

1.FVC : an increase of 10% or more 1.FVC : an increase of 10% or more

2.FEV1 : an increase of 200 ml or 2.FEV1 : an increase of 200 ml or 15% of the baseline FEV1 15% of the baseline FEV1

3.FEF25%-75% : an increase of 20% 3.FEF25%-75% : an increase of 20% or more or more

How Do I Read A PFT ?How Do I Read A PFT ?

Step 1. Look at the forced vital Step 1. Look at the forced vital capacity (FVC) to see if it is within capacity (FVC) to see if it is within normal limits. normal limits.

Step 2. Look at the forced expiratory Step 2. Look at the forced expiratory volume in one second (FEV1) and volume in one second (FEV1) and determine if it is within normal determine if it is within normal limits.limits.

Step 3. If both FVC and FEV1 are Step 3. If both FVC and FEV1 are normal, then you do not have to go normal, then you do not have to go any further - the patient has a any further - the patient has a normal PFT test. normal PFT test.

Step 4. If FVC and/or FEV1 are low, Step 4. If FVC and/or FEV1 are low, then the presence of disease is highly then the presence of disease is highly likely.likely.

Step 5. If Step 4 indicates that there Step 5. If Step 4 indicates that there is disease then you need to go to the is disease then you need to go to the %predicted for FEV1/FVC.%predicted for FEV1/FVC.

If the %predicted for FEV1/FVC is If the %predicted for FEV1/FVC is 88%-90% or higher, then the patient 88%-90% or higher, then the patient has a restricted lung disease. If the has a restricted lung disease. If the %predicted for FEV1/FVC is 69% %predicted for FEV1/FVC is 69% or lower, then the patient has an or lower, then the patient has an obstructed lung disease.obstructed lung disease.

Example # 1 Example # 1

Predicted Measured %PredictedPredicted Measured %Predicted

FVC 5.80 L 5.50 LFVC 5.80 L 5.50 L 95%95%

FEV1 4.93 L 4.90 L 99%FEV1 4.93 L 4.90 L 99%

FEV1% 85% 89% 104%FEV1% 85% 89% 104%

Example # 2Example # 2

Predicted Measured %PredictedPredicted Measured %Predicted

FVC 5.68 L 4.00 L 70%FVC 5.68 L 4.00 L 70%

FEV1 4.90 L 3.25 L 66%FEV1 4.90 L 3.25 L 66%

FEV1% 84% 81% 96%FEV1% 84% 81% 96%

Example # 3Example # 3

Predicted Measured %PredictedPredicted Measured %Predicted

FVC 4.50 L 2.63 L 58%FVC 4.50 L 2.63 L 58%

FEV1 3.80 LFEV1 3.80 L .80 L .80 L 21% 21%

FEV1% 84% 30% 36%FEV1% 84% 30% 36%