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All Lung Function Measures

 

Equipment:

 

• Spirometer
• Disposable spirometer mouthpieces

 

Introduction:

 

Good lung function is important for optimum health related fitness. Being able to breathe easily makes everyday tasks feel so much less arduous. Also during exercise, if your lungs are in good shape you will be not get out of breath so quickly. Smoking in particular, leads to poor lung function as does being overweight and unfit. Regular exercise will help strengthen the muscles of the chest and diaphragm which are vital for efficient breathing.

 

Tests of lung function and efficiency are extremely valuable to the physiologist, as chest x-rays do not give any indication of the volume of the lungs or the opening of the airways. Early detection of problems is important for successful treatment of respiratory defects before illness occurs. Sometimes these illnesses can be detected with a stethoscope but this does not provide enough technical detail. Measurement of lung function using Spirometry gives more information and provides a more permanent record. It also serves as a means of creating interest and awareness of the importance of good lung function. It may also be used to demonstrate the deleterious effects of smoking and to monitor the improvement and progress following a weight control or exercise program. It is a simple test to administer, is highly repeatable and is usually an extremely popular feature of community fitness testing projects.

 

Test Procedure:

 

The equipment used is called a Spirometer, which measures respiratory (breathing out) lung function. 

Follow the instructions for the model of Spirometer you are using. Usually you will be required to enter the Subject’s gender, height, weight and age when prompted.

 

 

1. Place a disposable cardboard mouthpiece into the flow head.
2. The subject should be lightly clothed i.e. with jacket or coat removed and tight clothing such as tie, collar or restrictive bra loosened. 
3. Carefully explain the procedure to the participant, ensuring that he/she is sitting erect with feet firmly on the floor.
4. Instruct the participant to “breathe in fully”
5. “Seal your lips around the mouthpiece”
6. “blast the air out as fast and as far as you can until your lungs are completely empty”
7. The subject holds the breathing tube in one hand, takes a deep breath and fills the lungs completely.
8. The subject then puts the mouth piece INTO the mouth, closes their lips around the tube and then blows out as hard and fast as possible, sustaining the effort for six seconds out loud so that the subject knows when to stop exhaling).

 

 

 

 

After a brief recovery period, Perform the test a second time ensuring that:

 

• The highest and second highest FVC should be within 0.2 L.
• The highest and second highest FEV1 should agree within 0.1 L.

 

Record the test results for the attempt which had the highest FVC & FEV1

Note: if the subject feels dizzy, after completing the test ask them to sit down and recover before repeating it.

 

Spirometry Test Essentials:

 

• A good seal on the mouthpiece
• Very vigorous effort right from the start of the manoeuvre and continuing until absolutely no more air can be exhaled
• Smooth rapid take off with no hesitation, cough, leak, tongue obstruction, glottic closure, vocalisation, poor posture, valsalva or early termination
• No leaning forward during the test
• Minimum of 2 acceptable blows

 

Reproducibility:          

 

• The highest and second highest FVC should be within 0.2 L.
• The highest and second highest FEV1 should agree within 0.1 L.

 

Remember, particularly in individuals with airflow obstruction, that it may take many seconds to fully exhale. It is also important to recognise those individuals whose efforts are reduced by chest pain or abdominal problems, or by fear of incontinence, or even just by lack of confidence. There is no substitution for careful explanation and demonstration – demonstrating the manoeuvre to the participant will overcome 90% of problems encountered and is critical in achieving satisfactory results.

 

Observation and encouragement of the client’s performance are also crucial. Be sure to examine the spirogram for acceptability and reproducibility. It is useful to learn how to recognise inadequacies in the performance of spirometry and the recordings as these can greatly affect the accuracy, reproducibility and hence interpretation of the results.

 

The most common patient-related problems when performing the FVC manoeuvre are: 

 

• Submaximal effort 
• Leaks between the lips and mouthpiece 
• Incomplete inspiration or expiration (prior to or during the forced manoeuvre) 
• Hesitation at the start of the expiration 
• Cough (particularly within the first second of expiration) 
• Glottic closure 
• Obstruction of the mouthpiece by the tongue 
• Vocalisation during the forced manoeuvre 
• Poor posture

 

Recordings in which coughing, particularly if this occurs within the first second, or hesitation at the start has occurred should be rejected.

 

Interpretation of results:

 

Spirometry is designed to measure FOUR factors relating to expiratory lung function.

 

LUNG VOLME or Forced Vital Capacity (FVC). This is the total amount of air that the subject can breathe out after completely filling their lungs and is measured in litres. You can see this very simply by blowing up a balloon with one big breath and comparing the size of your balloon with someone else. Lung Volume usually depends on your age, sex and height, being largest at around 20-25 years old males normally have bigger lungs than females and taller people generally have larger lungs than shorter people. The computer print out will indicate the normal range of lung volumes for your age, sex and height.

 

There are many reasons for FVC being lower than normal. For example, bronchitis, emphysema, asthma and other lung disorders will all affect lung volume. Smoking is one serious cause of lung damage. Being overweight can often reduce lung volume since the diaphragm has little room to move downwards and excess fat on the chest wall restricts expansion of the lungs.

 

Poor physical condition can lead to weak respiratory muscles and poorly developed lungs. However, since low FVC values have been identified as a risk factor in heart disease, steps should be taken to try and improve this. A recommendation to check this out with the doctor would be advisable.

 

LUNG STRENGTH or Forced Expiratory Volume in one second (FEV1). This is measured by how much air t he subject can forcibly expel in one second. This depends on a number of factors such as clear air tubes and ‘clean’ air sacs (alveoli) which are found at the ends of the tubes inside the lungs. Interestingly, if all the alveoli were taken out and laid on the ground these air sacs would cover the size of a tennis court. Also, lung strength depends upon strong respiratory muscles – the intercostals muscles of the chest and the muscles of the back, sides, stomach and neck. FEV1 values are most certainly affected by smoking and by the disorders mentioned above.

EFFICIENCY or Forced Expiratory Ratio (FER). This is a measure of the percentage of maximum lung volume that can be expelled in one second. Again, it depends on clear airways and efficient alveoli and gives a useful index on lung function.

 

PEAK EXPIRATORY FLOW RATE (PEFR) is a measure of the maximum speed or flow rate that the subject can generate during a forced exhalation and requires a combination of lung strength and lung power with clear and efficient respiratory passages. PEFR is measured in litres per minute.

 

Regular aerobic exercise, keep bodyweight under control and not smoking will all help improve lung function. Swimming, in particular, is for most people, an excellent form of ‘lung’ exercise. 

 

NOTE: If lung function is found to be substantially low, then advise the subject to check this out with their Doctor. A series of remedial exercises together with medical treatment may be necessary.

 

Peak Flow

If a peak flow measure only is required, follow the same procedure as for all measures but record only the Peak Expiratory Flow Rate (PEFR) in the Fitech application.