Getting Spirometry Right

It Matters!

Performance, Quality

Assessment, and

Interpretation

Susan Blonshine RRT, RPFT, AE-C, FAARC

Sample Title

• Recognize acceptable spirometry that

meets the “start of test” and “end of test

criteria”.

• Recognize an obstructive pattern

consistent with COPD or asthma.

Objectives

Sample TitleSpirometry: a 3-Step Process

1. Pre-test

2. Test

3. Post-test

a. Acceptability and

Repeatability

b. Report generation

Sample TitleSpirometer Preparation

(Equipment-dependent) Warm up

spirometer before patient arrives

Verify that the room is between

17º - 40º C (63º - 104º F)

Record room’s relative humidity and

barometric pressure

Sample TitleEquipment Function and Calibration

Each day of patient testing, use a 3-liter

syringe to verify proper equipment

function

Remember acceptable variance

105 ml

Range: 2.90 to 3.10

Sample Title

Never test patients on a system

that cannot pass calibration

checks

Patient Preparation

Sample TitleIntroductions and Information

Introduce yourself to the patient

Check patient identification

Briefly explain the procedure

Encourage questions, and answer them

in easily understood terms

Avoid using technical terms and

acronyms

Sample Title

Measure patient’s height to the nearest

centimeter or ½ inch

Patient should be measured in stocking

or bare feet

Gathering Demographic and Patient Information

Patient Training

Sample TitleSpirometry is effort-dependent

Understand testing needs

Be cooperative during the testing

process

The patient must:

Sample TitleSpirometry is effort-dependent

Good coaching can increase volume

10% to 15%

Sample TitleSpirometry is effort-dependent

Good technologist – patient

interaction is key to testing

success

Sample Title

The patient should be sitting during

testing (current ATS/ERS)

Patient may be standing with a chair

behind for occupational testing

Both feet should be on the floor

Testing Position

Sample Title

Tight clothing that may restrict

breathing should be loosened

Sample Title

1. The patient breathes in as deeply as possible, to Total Lung Capacity

2. The patient inserts the mouthpiece between teeth and presses the lips together

3. The patient blows out as fast and hard as possible to Residual Volume

Open-circuit Testing

Sample Title

1. The patient positions the mouthpiece

in his/her mouth and breathes normally

through the mouthpiece

2. The patient inhales as deeply as

possible to Total Lung Capacity

3. The patient blows out as fast and hard

as possible, completely to Residual

Volume

Closed-circuit Testing

Sample TitleTesting Position

Seated

Looking forward

Both feet on the floor

Instruct and demonstrate proper

posture during testing

Sample TitleHead Position

The head should be slightly elevated

The chin should be pointed forward

Sample TitlePlacement of the Mouthpiece

The patient places the mouthpiece in his/her mouth

The patient’s tongue goes under the mouthpiece

The patient’s lips should wrap tightly around the mouthpiece

The patient should not bite the mouthpiece

Sample Title

Patients wearing dentures should

remove them prior to testing

Sample TitleNoseclips

Explain how noseclips will be used

during testing, to force all breathing

through the mouthpiece

Sample Title

1. Place the mouthpiece in your mouth

2. Breathe in and out nice and easy

3. Breathe in as deep as possible

4. Blow out hard and fast

5. Keep squeezing all the air out for about six seconds or until you are told to breathe in deeply again

6. Take the mouthpiece out of your mouth and relax

Go Over Each Step

Sample TitleTesting Demonstration

Always demonstrate the test

procedure with animation and the

same level of effort that is expected

of the patient

Most patients should be able to

achieve an acceptable peak flow

Sample TitleInstruct Patient to

Sit up straight

Place the mouthpiece in his/her mouth

Breathe in as deeply as possible

Sample Title

Observe the patient’s effort and

accessory muscles

Sample Title

Instruct the patient to blow out hard

and fast

Watch the system’s graphic displays

as the patient blows out

The patient should not hold his/her

breath at Total Lung Capacity

Sample Title

Instruct the patient to continue to

squeeze all the air out for at least 6

seconds, or the volume-time curve

shows a 1-second plateau

Sample Title

When a flow-volume “loop” is being

performed, tell the patient to breathe

back in as rapidly as possible, to

Total Lung Capacity

Sample TitleBetween Trials

Instruct the patient to remove

mouthpiece and rest between trials

Use rest time between trials to re-

instruct, as needed

Maneuver Performance

• Three acceptable maneuvers

• Practical upper limit of 8-clinical judgement

Satisfactory start of test

• Back extrapolated volume

less than 5% or 150 ml

• Pause at TLC greater than

4-6 seconds decreases PEF

and FEV1

End of test criteria

• Obvious plateau of 1 second

• Minimum exhalation time

• Six seconds

Volume-Time Curve

Asthma Initiative of Michigan, 2005.

Acceptability Criteria

• Was end of test criteria met? ( 1 second

plateau)

• Was there a minimum exhalation time of 6

seconds?

• Was the start of test satisfactory? (Less than

5% back-extrapolation)

• Did the subject understand the instructions?

Acceptability Criteria

• Was inspiration performed with maximum effort?

• Was exhalation smooth and continuous?

• Was effort maximal on expiration?

• Are there at least 3 acceptable maneuvers?

(all 7 criteria must be met)

Repeatability

• Is the variance less than .15 L between the

largest and second largest FVC

• Is the variance less than .15 L between the

largest and second largest FEV1

• Is there documentation for lack of

repeatability?

Sample Title

Have 3 acceptable tests been

performed?

Has repeatability criteria been met?

Have 8 or more tests been performed?

Can/should the patient continue

testing?

Are the inspiratory flow patterns

repeatable with maximal effort?

Deciding when Testing is Complete

Error Recognition and Correction

A skilled technologist can

recognize the following common

errors and take necessary

corrective measures

Nonconsistent

Spirometry Flow Chart

Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spirometry.

Eur Respir J. 2005;26:319-338.

Reference Values

• Height must be accurate

• Match to patient population

– NHANESIII (8-80)

– Wang (<8)

• Use LLN

– 95% confidence interval

Reference Values

• Using .70 as a fixed lower limit for

FEV1/FVC ratio increase false positive

results

– Males >40 and females >50

• Reference author should be noted on report

– Author’s last name and date of

publication

ATS/ERS Interpretation - Obstruction

•For identification of obstruction

Use LLN for FEV1/VC

NOT a fixed ratio of 0.70 (GOLD and ATS COPD

recommendation)

•Roberts SD, et. al. FEV1/FVC Ratio of 70% Misclassifies Patients With

Obstruction at the Extremes of Age. Chest 2006;130;200-206

*Also see Falling Ratio Working Group at:

http://www.spirxpert.com/controversies/controversy.html

ATS/ERS 2005

Barreiro and Perillo, 2004.

National Asthma Council, 2005.

Normal

Obstruction

Restriction

Sarah, respiratory therapist

• Age: 52 years

• Her roommate has been complaining about Sarah’s

chronic cough and expectoration

• Patient has had a productive cough most mornings

for >5 years and occasional sinus headaches

• Otherwise, she reports “perfect health”

– Does not exercise much

– Denies dyspnea

Finding Pre-Value (L) %Pred

Postbronchodilator %Pred

FVC 2.7 63 3.3 77

FEV1 1.3 38 1.6 47

FEV1/FVC 48% 48%

Petty and Enright, 2005.

Example 1

Pred Actual %Pred

FVC 5.00 6.00 120%

FEV1 3.96 4.80 121%

FEV1/FVC 79% 80% 101%

A. Normal

B. Obstruction

C. Restriction

A. Normal

B. Obstruction

C. Restriction

Example 2

Pred Actual %Pred

FVC 5.00 3.00 60%

FEV1 3.96 3.00 76%

FEV1/FVC 79% 100% 127%

A. Normal

B. Obstruction

C. Restriction

D. Unacceptable

Example 3

Pred Actual %Pred

FVC 5.00 5.00 100%

FEV1 3.96 3.47 88%

FEV1/FVC 79% 69% 87%

A. Normal

B. Obstruction

C. Restriction

D. Unacceptable

A. Normal

B. Obstruction

C. Restriction

D. Unacceptable (Cough)

Example 4

Pred Actual %Pred

FVC 5.00 1.80 36%

FEV1 3.96 1.78 45%

FEV1/FVC 79% 99% 125%

A. Normal

B. Obstruction

C. Severe Restriction

D. Unacceptable

SPIROMETRY INTERPRETATION

1. Check graph for maneuver

ACCEPTABILITY and REPEATABILITY

2. Low FEV1/FVC ratio = obstruction

3. Low FVC, high FEV1/FVC = suggests

restriction

Any Questions

Susan Blonshine BS, RRT, RPFT, FAARC, AE-C

TechEd Consultants, Inc.

www.techedconsultants.com

sblonshine@techedconsultants.com

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