GVS Lung Function Test Filters

Pulmonary function tests are used to measure breathing and how well the lungs are functioning. The main tests carried out are Spirometry, Diffusion and Body Plethysmography.


Spirometry is the most common of the lung function tests, measuring lung function, in particular the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is an important tool used to assess conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD (Chronic Obstructive Pulmonary Disease). The spirometry test is performed using an instrument called a spirometer. During spirometry test, the patient places their mouth over a mouthpiece connected to the spirometer, takes a deep breath in and then blows out as forcefully as possible.

Lung Diffusion Test

It assesses how well oxygen passes from the lung’s air sacs (alveoli) into the blood stream. This test measures the diffusing capacity of the lungs for carbon monoxide. During the test the patient is sitting down, a mouthpiece is fit tightly around the mouth and a nose clip positioned to prevent breathing via the nose during the test. The patient then inhales a small amount of carbon monoxide gas, holds the breath for 10 seconds and then exhales as fast as possible. The exhaled gas is then analysed to determine how much carbon monoxide the body absorbed during the breath.

Peak Flow Test

The peak flow test (peak expiratory flow test or PEF) is a lung function test to measure how fast a person can breathe out. The peak flow test is performed using a device peak flow meter. During the test the patient takes a full breath in, then blows out as fast as possible into the flow meter, the measurement taken is the peak flow.

Different pulmonary function tests measurements include:

VC - Vital Capacity The volume of air exhaled from the lungs after a full inhalation

FVC - Forced Vital Capacity The volume of air forcibly exhaled from the lungs after taking the deepest breath possible

RV - Residual Volume The volume of air remaining in the lungs after exhalation

TLC - Total Lung Capacity The maximum volume of air that the lungs can hold

FEV1 - Forced Expiratory Volume in One Second The volume of air which can be forcibly exhaled from the lungs in the first second of a forced exhalation

FEV1/FVC-FEV1 - Percent (FEV1%) The ratio of FEV1 to FVC tells the clinician what percentage of the total amount of air is exhaled from the lungs during the first second of forced exhalation

PEFR - Peak Expiratory Flow Rate Measures if treatment is effective in improving airway diseases such as COPD

FEF - Forced Expiratory Flow Measures exhaled volume of air to indicate if a large airway obstruction is present

MVV - Maximum Voluntary Ventilation A value determined by having the patient inhale and exhale as rapidly and fully as possible in 12 seconds. The results reflect the status of the muscles used for breathing, how stiff the lungs are and if there is any resistan- ce in the airways. Indicating how strong a patient's lungs are prior to surgery. Poor performance suggests that respiratory complications may occur after surgery

Body plethysmography
Body plethysmography is a pulmonary function test that determines how much air is in the patient’s lungs after taking a deep breath. It also measures the amount of air left in the lungs after the patient exhales as much as they can.

Advantages of using Bacterial Air Filters for Pulmonary Function Testing
Pulmonary tests require an Air Filter to be placed between the patient and the lung function equipment. The reasons for this are explained below:
- To protect the equipment components, as infective droplets may be expelled and potentially degrade the equipment.
- To minimize the risk of cross infection: by far the greatest risk would be for a subsequent patient carrying out the same test, who could inhale any infective droplets deposited in the machine. The potential danger of this is demonstrated by the fact that the infective dose for a disease, such as tuberculosis, may be as low as than 10 bacteria. Patients with chronic respiratory diseases will be at increased risk of respiratory infection.
It is always recommended to calibrate the equipment with the filter installed, as this last will cause resistance that could affect the results of the tests.

Selecting the Air Filter
The design of air filters for use in lung function equipment needs to take three factors into account:
- The Air Flow rate.
- The level of Resistance.
- The Efficiency of the filter at preventing particulate penetration.

GVS Spirometry Filters
GVS provides Filters for Lung Function Testing (Spiroguard) with proven filtration efficiency of 99,9999% up to 0,027 micron. GVS Spiroguard enables testing without the risk of cross contamination for patients and health care professionals, as well as equipment. GVS’s compact design Spiroguard are all manufactured to a high quality and hygienically packed in a clean room to ensure maximum protection against contamination.

GVS Filter Media
GVS Spiroguard utilise an electrostatically charged synthetic media. The positive and negative charge on filter fibres is generated during the manufacturing process and enhances the filter’s ability to attract particulate matter. Unlike other spirometry filters, GVS’s electrostatic filter media is covered in a protective scrim layer. This prevents fibres becoming loose, blocking the spirometer and therefore enhancing protective performance against harmful contamination.
The filter media has hydrophobic properties to minimise droplet contamination, as well as providing a low resistance and low dead space to improve the validity and consistency of respiratory testing results and minimise rebreathing.