getting the most out of office spirometry · getting the most out of office spirometry. ......

Nurse Practitioner / Certified Asthma Educator

Ferrell-Duncan Clinic, Department of Allergy & Immunology

Coordinator, CoxHealth Asthma Center

[email protected]

Michelle Dickens RN FNP-C AE-C

GETTING THE MOST

OUT OF OFFICE SPIROMETRY

Disclosures

•No financial relationships to disclose

•No off-label medication use will be discussed

Objectives

•Discuss and demonstrate the technique for performing spirometry

•Explore the concepts of acceptability and reproducibility

•Apply the use of the FEV1/FVC ratio to an office spirometry

protocol

SPIROMETRY BASICS

Definitions

“PFT’s”

vs

“Spirometry”

Definitions

PFT’s (pulmonary function tests)

•A generalized term that refers to a number of diagnostic

tests that measure the function of the respiratory system

•Includes: spirometry, absolute lung volumes, diffusing

capacities, even ABG’s

•Fruit analogy

•PFT’s=fruit, spirometry=apple

Definitions

Spirometry

•Measurement of dynamic lung volumes.

•Measures the rate at which the lung changes volume

during forced breathing maneuvers. (Hyatt, Scanlon,

Nakamura)

•How much air a patient can breathe out and how fast they

can do it. (me)

This assumes the equipment has been properly maintained and calibrated each

day prior to use. Check your equipment’s manual to determine whether

calibration is required (some smaller units do not require calibration).

Integrity of Equipment

Spirometry Procedure

Step 1: Get height (without shoes) and weight

Step 2: Assess for contraindications (recent surgery, MI, pneumo)

Step 3: Perform forced expiratory maneuver

1. Apply nose clips; mouthpiece between teeth

2. Start with a few normal breaths

3. Take a deep breath in

4. Blast out hard and fast, continue until airflow reaches a plateau (min 6 seconds for adults, 3 seconds for children)

5. Take a deep breath in

Step 4: Repeat minimum of three times

http://allergynotes.blogspot.com/2014/05/lung-function-test-spirometry-video.html


http://allergynotes.blogspot.com/2014/05/lung-function-test-spirometry-video.html

For Pre/Post Bronchodilator Testing

1. Perform initial spirometry

2. Administer 4 puffs of albuterol or levalbuterol using a spacer

(wait 30 seconds between puffs)

3. Wait 10-15 minutes and repeat spirometry (minimum of 3

attempts)

• http://www.thoracic.org/statements/resources/pfet/PFT2.pdf


http://www.thoracic.org/statements/resources/pfet/PFT2.pdf

Sample Spirometry Report Layout

PreTest raw

values and

comparison

to predicted

Patient

demographics

PostTest raw

values and

comparison to

predicted (if

bronchodilator

given)

Percentage of

change (if

bronchodilator

given)

Flow-volume

loop tracing

Volume-time

curve

tracing

Info regarding

calibration and

reference tables

used

Predicted

values

Other Important Values:

FET = Total amount (in seconds) that a patient exhales

• Important when looking at acceptability

• At least 6 seconds for adults, 3 seconds for children

FEV1/FVC (“The Ratio”) = Calculated value based on FEV1 and FVC

measured, expressed as ratio/percentage

Volume (how much) Flow (how fast)

Unit of

measure

Liters Liters/second

Common

values

FVC = Forced Vital Capacity

FEV1 = Forced Expiratory Volume in 1 sec

PEF = Peak flow rate

FEF25-75 = Forced Expiratory Flow rate middle half of

maneuver

Important Values Measured with Spirometry

The Ratio

•Percentage of a patient’s forced vital capacity that can be exhaled in the first second (FEV1/FVC x100 = ratio)

•Doesn’t get compared with predicted values based on height, gender, or race. “Normals” are based on age.

Normal: <20 years ≥ 85%

20-39 years ≥ 80%

40-59 years ≥ 75%

60-80 years ≥ 70%EPR-3 Guidelines 2007

The Ratio

•Interpretation of FEV1 without taking the FVC into

consideration can be misleading

•Patients who usually have results >100% of predicted (large

lungs) can have obstruction even with “normal” results based

on predicted values

•The “Ratio” = FEV1/FVC gives a true representation of the

degree of obstruction

ACCEPTABILITY AND REPRODUCIBILITY

(a.k.a. “The Importance of Coaching”)


Assessing Acceptability


(https://courses.washington.edu/med610/pft/pft_primer.html)

Assessing Acceptability - Flow Volume Loop

Review the shape of the expiratory loop:

Normal loop

(Hyatt, Scanlon, & Nakamura, 2009, p. 16)


UNACCEPTABLE – Hesitation before blasting



UNACCEPTABLE – Not blasting with maximal effort



UNACCEPTABLE – Stopped and restarted



UNACCEPTABLE – Cough during maneuver



UNACCEPTABLE -- Stopping too soon



So how do

you know

when to

stop . . .

End of Test Criteria:

Pt cannot physically blow any more

OR

Volume-time curve shows no change in volume (<0.025L)

for >1 second AND patient has exhaled for minimum time

(>6 sec for adult, >3 sec for child)

(https://www.spirometry.guru/spirometry.html)

Assessing Acceptability – Volume-Time Curve

• Air leak around mouthpiece

• Occlusion of mouthpiece with tongue or teeth

• Extra breaths during maneuver

Assessing Acceptability – Other Exclusions

ACCEPTABLE – “Knee” variation – normal variant,

especially in young, non-smoking women



• Patient needs to demonstrate at least three tests that are similar

to be considered reproducible

• If post-testing is done, three more tests that are similar to each

other are required

• Many machines will give feedback regarding the consistency of

the testing or indicate when additional trials are needed. You

shouldn’t need to calculate the reproducibility manually (see next

slide).

Assessing Reproducibility


Assessing Reproducibility


DEVELOPING AN OFFICE

PROTOCOL FOR SPIROMETRY

• At what point in the visit is spirometry performed?

• Which patients get spirometry?

• How often should it be performed?

• When and how should post-bronchodilator testing be performed?

Note—sample protocols included here are for illustration purposes

only. Protocols should be individualized to each clinic location and

circumstances.

Questions to be answered before developing a protocol

This basic question should be answered before any protocols are

developed.

If spirometry is performed prior to the provider visit, protocols should

include the common indications and intervals for testing.

If the provider always see the patient first and then orders the

spirometry, the indication and testing intervals are not needed within

the protocol.

At what point in the visit is spirometry performed?

Protocol should include indications if staff will be expected to

perform spirometry prior to provider visit.

Possible indications:

✓History of asthma

✓History of COPD

✓Wheezing

✓Shortness of breath

✓Dyspnea on exertion

✓Cough

Which patients get spirometry?

Protocol should include time intervals if staff will be expected to

perform spirometry prior to provider visit.

Based on EPR-3 guidelines, perform spirometry:

•At the initial assessment

•After treatment is initiated and symptoms have stabilized

•During periods of progressive or prolonged loss of asthma control

•At least every 1–2 years; more frequently depending on response

to therapy

How often should it be performed?

Protocol should include criteria to perform post-bronchodilator

testing based on initial results and/or patient characteristics

Protocol should also list out the bronchodilator medications and

doses to be used during pre/post testing.

When & how should post-bronchodilator testing be performed?

Examples of criteria for post-testing (may need several included in protocol):

✓An absolute FEV1/FVC ratio less than expected as below:

Age Ratio

<20 years 85%

20-39 years 80%

40-59 years 75%

60-80 years 70%

✓An FEV1 less than XX% of predicted (determine the appropriate lower cutoff)

✓Smoking history

✓On home bronchodilator therapy

✓Specific provider order regardless of results

When should post-bronchodilator testing be performed?

Why use the ratio as a criteria for post-bronchodilator testing?

•Patients who usually have results >100% of predicted (large

lungs) can have obstruction even with “normal” results based

on predicted values

•If you just look at the FEV1, you might see a “normal” number,

even above 100% of predicted. However, if the patient has

large lungs, he/she might still be blowing out less air than

expected (aka obstruction from asthma or COPD)


At first glance, these results look pretty good.


But once the FEV1/FVC ratio is obtained, you see that the patient is

actually having a lot of trouble exhaling a normal proportion of his air

(13 year old boy, normal =>85%).

Tip: If your machine gives a predicted value for

the ratio, ignore it. The ratio is only compared

to the age chart. Some machines have the

ability to turn off this value in the settings.


Patient demonstrated a 24% and 670ml improvement in FEV1

following bronchodilator, which is consistent with asthma.

The diagnosis of asthma would have been missed in this patient if

post-bronchodilator spirometry wasn’t performed.

Low Limit Normal (LLN)

(2.85 L)

FVC Predicted Value

(3.50 L)

High Limit Normal (HLN)

(4.17 L)

How can the FEV1 be normal with obstruction?

Patient’s

FVC 4.01

Low Limit Normal (LLN)

(2.41 L)

FEV1 Predicted Value

(2.99 L)

High Limit Normal (HLN)

(3.57 L)


Patient’s

FEV1 2.75


Patient is HERE Should be HERE

Represents a 25% drop

Sample protocol:

A determination of airflow-limitation reversibility with drug administration is

commonly undertaken as a part of lung function testing.

Dosing is as follows:

• 4 puffs, (90 mcg/puff) of albuterol

OR

• 4 puffs, (45 mcg/puff), of levalbuterol

• Each puff is to be given with a spacer, should be 30 seconds apart with a

deep inhalation, & 5 second breath-hold

How should post-bronchodilator testing be performed?

•Read the manual to understand your specific equipment

•Practice good coaching techniques

•Start assessing acceptability and reproducibility on all your tests

•Look at FEV1/FVC ratio on every patient

•Encourage your providers to order post-bronchodilator testing if

ratio is low, even if a protocol isn’t used

•Ensure bronchodilator doses are adequate if doing pre/post testing

•Discuss the need for a spirometry protocol in your office to

streamline the process and ensure consistency in testing

Next Steps

Michelle Dickens RN FNP-C [email protected]

getting the most out of office spirometry · getting the most out of office spirometry. ......

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