Understanding Spirometry

Spirometry Interpretation Workshop

Saturday 13 August 2017

Presenters

Professor Lutz Beckert, Professor of Medicine, University of Otago, Christchurch

Respiratory Physician, Canterbury District Health Board, Christchurch

Dr Maureen P Swanney, Scientific Director, Respiratory Physiology Laboratory,

Canterbury District Health Board, Christchurch

Contributors to case presentations

Clinical Respiratory Physiologists: Rachel Kingsford, Laura Ploen and Emily Ingram

Guideline for Spirometry Interpretation

1 Quanjer PH, Pretto JJ, Brazzale DJ, Boros PW. ‘Grading the severity of airways obstruction: new wine in new bottles’, Eur Respir J, 2014; 43: 505-512

2 ATS/ERS Task Force 2005, ‘Standardisation of lung function testing: Interpretative strategies for lung function testing’, Eur Respir J, 2005; 26: 948–968

Interpretation of Bronchodilator Response

An increase in FEV1 and/or FVC of 12% and 200 mL from the control (baseline value)

constitutes a positive bronchodilator response1.

Case 1B

Joseph comes to see you for an opinion about his recurrent chest infections which have not

cleared up over the last two months. Apart from associated shortness of breath, he is well

and stopped smoking 40 years ago.

You request spirometry.

Interpretation

These results suggest an underestimation of the vital capacity and need to be interpreted

with caution.

The FEV1/FVC ratio at 48% is below the Lower limit of normal (LLN) of 58% and would have

been even lower if the expiratory manoeuvre had continued long enough to achieve a

plateau in volume.

Based on a FEV1 Z-Score of -3.01 these results suggest airway obstruction. Using the percent

predicted FEV1 of 35%, the severity of obstruction is very severe.

Spirometry after the administration of a bronchodilator may inform the presence of any

reversible component. However, the likely clinical diagnosis in this context is severe COPD.

Case 2B

Grace is a 53 year old woman who has been invited to walk the Milford Track by her

daughter. Grace hasn’t done much exercise lately and when she does, like climbing stairs,

she feels short of breath. She wonders if she is just unfit or whether she has any lung

damage.

You request spirometry.

Interpretation

Technically the spirometry has been performed well. Grace had a great effort with a total of

15 seconds exhalation time.

The FEV1/FVC ratio at 29% is below the lower limits of normal of 68%.

Her FEV1 measures as 0.61L. Based on a FEV1 Z-Score of -5.28 these results suggest airway

obstruction. Using the percent predicted FEV1 of 21%, her obstruction is very severe.

Spirometry after the administration of a bronchodilator may inform the presence of any

reversible component. However, the likely clinical diagnosis in this context is severe COPD.

Case 3B

Reginald is a 70 year old man who has been diagnosed with lung cancer in his right upper

lobe. He is feeling well in himself, however the surgeons have requested pre-operative

spirometry.

Interpretation

Technically the spirometry has been performed well. Reginald had a great effort exhaling for

almost 14 seconds.

The FEV1/FVC ratio at 28% is below the lower limits of normal 63%.

His FEV1 measures as 1.09L. Based on a FEV1 Z-Score of -3.49 these results suggest airway

obstruction. Using the percent predicted FEV1 of 37%, he has severe airflow obstruction.

Spirometry after the administration of a bronchodilator may inform the presence of any

reversible component. However, the likely clinical diagnosis in this context is severe COPD.

A FEV1 of approximately 1 litre makes him a borderline candidate for a lung resection; we

often go ahead with an upper lobe resection, because the upper lobe does not essentially

contribute much to gas exchange.

Case 4B

Genevieve is coming to see you with her mother. She has strong academic records but hates

all sports. On direct questioning she reports a cough and funny noise in her chest when she

exercises.

You request spirometry.

Interpretation

This is a technically accurate spirometry test.

The FEV1/FVC ratio of 47% is significantly below the LLN of 78%.

Based on an FEV1 z-score of -4.68 these spirometry results indicate airways obstruction.

Using the %predicted FEV1 at 42%, the severity if obstruction is severe.

After the administration of Salbutamol there was a 115% and 1500 mL increase in FEV1 and

17% and 490 mL increase in FVC, indicating a significant reversibility of airways obstruction.

She has asthma.

Case 5B

Vanessa has finally become pregnant. She is fit and well and has no problems. She has been

on low dose beclomethasone since her teenage years and wishes to stop this during her

pregnancy.

You request spirometry.

Interpretation

This is an accurate and repeatable spirometry test.

The FEV1/FEV ratio of 68% is below the LLN and z-score at -2 indicates airways obstruction.

Her FEV1 of 4.10 L is above the expected normal for a female of this age and height

suggesting a very mild obstructive deficit.

Following the administration of Salbutamol the FEV1 has increased by 16% and 660 ml, there

was no significant increase in FVC.

Should she stop her beclomethasone?

Case 6B

Jeannette is a 70 year old woman who has worked hard all her life and is now retired on a

lifestyle block. She is now becoming too short of breath to feed her donkeys. She is coming

to see you for ‘some puffers’.

You request spirometry.

Interpretation

The end of test plateau was not quite reached. Exhaling for only 10.4 seconds may result in

an underestimate of her forced vital capacity (FVC).

Even with a possible underestimated vital capacity her FEV1/FVC ratio at 40% is below the

lower limit of normal of 65%.

Her FEV1 measures as 0.42L. Based on a FEV1 Z-Score of -4.38 these results suggest airway

obstruction. Using the percent predicted FEV1 of 22%, her obstruction is very severe.

Spirometry after the administration of a bronchodilator shows no reversibility, but this may

be underestimated because she took her Tiotropium less than72 hours ago. However, the

likely clinical diagnosis in this context is very severe COPD.

Case 7B

Tom is a 75 year old man who has been on Amiodarone for his atrial fibrillation for the last

three months. He is still in AF with a rate around 100 beats per minute and is becoming

short of breath on exertion. You wonder if he has smoking related disease, heart failure or

Amiodarone lung.

You request spirometry.

Interpretation

Technically the spirometry exhalation time doesn’t reach 6 seconds which may reflect an

underestimate of the vital capacity (FVC).

The FEV1/FVC ratio at 93% is above the reference range.

His FVC measures 2.19L. Based on a FVC Z-Score of -2.30 these results suggest a restrictive

spirometry pattern. Using the percent predicted FVC of 63%, he has moderately severe

restrictive lung disease.

One must not lose sight of the fact that the FVC may just be a technical underestimate

because of the early glottis closure. However, given the clinical scenario, enough suspicion

has been raised to suggest full lung function tests with a measurement of the Total Lung

Capacity (TLC) and Diffusing Capacity for Carbon monoxide (DL,CO). A CXR should also

considered.

Case 8B

Kenneth presented with acute chest pain. His angiography shows widespread disease and

he is being considered for emergency by-pass surgery. The anaesthetists request urgent

spirometry.

Interpretation

Weight and height have been transposed. It is more likely that Kenneth is 167cm high and

69kg (BMI 24.7). Technically the spirometry was performed well.

We can state that Kenneth has obstructive airways disease based on his FEV1/FVC ratio of

36%.

It is difficult to estimate the severity of his airways disease, however, a FEV1 of about 1.15L

is not great.

He has an improvement in his FEV1 from 1.15L to 1.40L, which is 250ml and 22% suggesting

reversible airways disease.

We had better ask the operator to change the height and weight around to be able to use

the correct reference values. He may be at increased operative risk. Also, he may develop

adverse reaction with treatment of a beta-blocker.

Case 9B

Grace’s parents have moved from the Westcoast to have better access to medical care. She

is tall, slim and becomes short of breath on exertion. She wonders if she is lacking energy

because she can’t gain weight.

You request spirometry.

Interpretation

She has used the spirometer as a peak flow meter and exhaled for about 1 second.

It is not possible to interpret this spirometry.

Case 10B

Colin grew up in Azerbaijan and worked for a while in an ammunition factory. Eventually he

emigrated via Turkey to the European Union and has now been accepted as a steel worker

in New Zealand. He is becoming short on breath on exertion.

You request spirometry.

Interpretation

Technically the spirometry has been performed well. Colin managed to exhale for 15

seconds.

The FEV1/FVC ratio at 64% of predicted is with the reference range (62 – 76).

His FVC capacity measures 3.74L and has a Z-score of 0.22 and is 104% predicted.

Despite his occupational exposure, Colin doesn’t seem to suffer lung disease, the spirometry

test is normal.

Case 11B

Bruce used to smoke while working at the freezing works to warm up and to counteract the

smells; he stopped almost 30 years ago. Over the last few years he has become increasingly

short of breath and wonders if it is old age or his previous cigarette smoking that is causing

his symptoms.

You request spirometry.

Interpretation

The spirometry exhalation time is 9 seconds. The need for using both a mouthpiece and a

face mask to measure spirometry suggests some facial muscle weakness.

The FEV1/FVC ratio is 69% which is above his reference lower limit of normal of 60%.

His FVC measures as 2.05L. Based on a FVC Z-Score of -2.11 these results suggest restrictive

spirometry. Using the percent predicted FVC of 63%, he has moderately severe restrictive

lung disease.

Using the face mask the FEV1/FVC ratio is 71%. However, his FVC is now 2.42L and within

the reference range (2.31 – 3.24), albeit at the lower end.

Given the clinical scenario, enough suspicion has been raised to suggest full lung function

tests with a measurement of the Total Lung Capacity (TLC) and Diffusing Capacity for Carbon

monoxide (DL,CO).

Case 12B

Barry has problems keeping up with his wife during their weekend walks. He used to have

asthma as a child but grew out of it. He used to smoke but stopped on his 50th birthday. He

is feeling well in himself but has an occasional cough and wheeze.

You request spirometry.

Interpretation

This spirometry test cannot be interpreted because there is an error in the gender which has

been recorded incorrectly. The reference values are consequently less than they should be.

However, you can comment that Barry had a good effort and exhale for 10 seconds. His FVC

may be an underestimate.

Even with a possible underestimate of this FVC his measured FEV1/FVC ratio is 45% with a z-

score of – 3.

His FEV1 is reduced to 0.98 L. Although the z-score will not be accurate because of the

gender mix-up, we can be certain it is reduced. He has obstructive airways disease.

It would be helpful to ask the operator to correct the data entry error to provide an accurate

reference range.

After administration of Salbutamol 400 mcg, his FEV1 improved by 202ml and 20%. He does

have significant reversibility in his FEV1.

Case 13B

Margaret is a 73 year old woman presenting to the emergency department not being able to

walk or breathe properly. It all started suddenly after an episode of vomiting and diarrhoea.

You request spirometry.

Interpretation

Technically the spirometry doesn’t reach 6 seconds and may reflect an underestimate.

However, the operator reported that the test was technically accurate and repeatable.

The FEV1/FVC ratio is above the reference range with a FEV1/FVC of 82%.

Her FVC measures 1.05L. Based on a FVC Z-Score of -3.63 these results suggest restrictive

spirometry. Using the percent predicted FVC of 41%, she has moderately severe restrictive

lung disease.

One must not lose sight of the fact that the FVC may just be a technical underestimate

because exhalation time was only 3 seconds. However, given the clinical scenario, enough

suspicion has been raised to suggest full lung function tests with a measurement of the

Total Lung Capacity (TLC) and Diffusing Capacity for Carbon monoxide (DL,CO). A

neurological examination may show the features of Guillain-Barre Syndrome.

Case 14B

Maddison used to have asthma as a child but grew out of it as an adult. During her

pregnancy she stopped all inhalers. She has joined a gym and is reporting a cough and

wheeze on exertion. She had to stop spin classes because of breathlessness.

You request spirometry.

Interpretation

This is a technically accurate and repeatable spirometry test.

The FEV1/FVC ratio of 76% is above the LLN of 71% which rules out significant airways

obstruction.

The FVC of 3.05L is just above the LLN of 2.92 indicating a normal spirometry test on this

occasion of testing.

What do you think is her clinical diagnosis?

Case 15B

Beverly had asthma all her life and has never smoked. She has been increasing her asthma

medication however she does not feel it is working anymore because she continues to

wheeze. She reports a constant cough, a feeling of something stuck in her throat and

frequent asthma attacks.

You request spirometry.

Interpretation

This is a technically accurate and repeatable spirometry test, although the technical

comments are missing.

The FEV1/FVC ratio of 75% is above the LLN and z-score at -1 is within the expected normal

range.

Similarly the FVC of 3.75 L is above the LLN of 2.55 and z-score at 0.66 is within normal

limits.

The truncated shape at high flow suggests an upper airway abnormality that need to be

investigated.

Case 16B

Monique is coming to see you with her father. She has an irritating cough which often wakes

her at night. Her parents have noticed a funny sound in her chest when laughing and when

playing with her older siblings.

You request spirometry.

Interpretation

This is a technically accurate and repeatable spirometry test.

The FEV1/FVC ratio of 75% is below the LLN of 80% and the z-score at -2 indicates airways

obstruction. (Note, it is lower than the LLN, however, it is above 70%)

Her FEV1 of 1.15 L is above the LLN of 1.05 L which can be classified as a mild obstructive

pattern.

The FEV1 has improved by 28% and 310 mL showing significant reversibility. The FVC has

increased by 12% and 190 ml which is not significant.

What do you think may be her clinical diagnosis?

Case 17B

Elizabeth has been working at the local chicken factory for the last few years and hates the

cold room. Several of her colleagues have been given duties outside the cold room because

of asthma. Elizabeth is coming to be checked out to make sure her lungs are alright.

You request spirometry.

Interpretation

Despite the shortcoming of the technique the FEV1/FVC ratio at 71% is within the normal

range with a z-score of -0.38.

Her FVC is 3.73L, which has a z-score of 0.77 or 114%. This is within normal limits.

Clinically, although the cold room is unpleasant no obstructive airways disease has been

detected. If clinical indicted bronchodilator challenge testing could be considered.

Case 18B

Nicola lives in Nelson in a community who have considerable success with organic farming.

She has a good nutrition and has been hoping to treat her asthma naturally.

Your request spirometry and a methacholine challenge test.

Interpretation

The FEV1/FVC ratio of 64% is below the LLN of 67% and the z-score at -2 indicates airways

obstruction.

Her FEV1 of 1.80 L is above the LLN of 1.59 L which can be classified as a mild obstructive

pattern. (Even though the FEV1 is essentially normal)

The Methacholine challenge test shows moderate bronchial responsiveness

She has asthma and easily loses about one litre in her FEV1. There is no evidence for

‘natural asthma treatment’. She should be recommended to take the standard dose of an

inhaled corticosteroid. She should be offered a written management plan.

Case 19B

Andrew has been working in the local post office and has been thinking of joining the fire

brigade. As part of the Fire Service screening they require a baseline spirometry. He is here

to discuss his results.

You request spirometry.

Interpretation

This is a technically accurate and repeatable spirometry test.

The FEV1/FVC ratio of 72 is just above the LLN of 71%, the z-score of -2 is borderline for

obstructive airways disease.

The FVC of 3.68 L is marginally above the LLN of 3.64 L and the z-score at -1.57 is within the

normal range. There is no significant reversibility because 12% and 200 mL was not achieved

for either FEV1 or FVC.

His FEV1 is below the lower limits of normal with 2.64L or a z-score of -2.27 or 71%

predicated. That would be suggestive of borderline (normal FEV1/FVC) ratio mild airways

obstruction.

His FEV1 shows a reversibility from 2.64L to 2.84L, i.e. 200ml and 8%. That does not fulfil the

criteria set for significant reversibility testing.

Considering the clinical questions and the patient’s symptoms, you may wish to request a

hypertonic saline challenge test.

Case 20B

Dorothy has never smoked but becomes short of breath on exertion. She often has a

prolonged cough following a viral infection but never recalls any wheezing.

You request spirometry.

Interpretation

Technically the spirometry is accurate and reproducible, Dorothy exhaled for 7.3 seconds.

The FEV1/FEV ratio of 77% is above the LLN of 63% and the z-score at 0 is within the normal

range.

The FVC of 2.35 L is above the expected normal for a female of this age and height

suggesting a normal spirometric pattern. Following the administration of Salbutamol the

FEV1 has improved by 16% and 290 ml, the FVC has also increased by 12% and 290 ML

showing significant reversibility.

Clinically she should be considered for investigations of adult onset asthma.