Respiratory diseases are the most common cause to visit doctors in India, especially Asthma and COPD, which have wide variations in morbidity and mortality in various geographic locations. India has the 4thlargest cases of asthma in the world but leads in the most number of asthma patient death in the world. Asthma is a chronic disease that affects the airways, causing swelling and increased mucus(inflammation) and squeezing the muscles around the airways (bronchospasm). Chronic obstructive pulmonary disease (COPD) is preventable and treatable shortness of breath or feeling tired. COPD is the second most common disease in India after HeartAttack.It is not only caused by smoking but also by biomass. COPD is one of the leading non-communicable causes of death globally and in India. People with COPD may feel short of breath when they exercise early in the disease. It can be hard to breathe out (exhale) or even breathe in (inhale). Guidelines for treating all these diseases are based on parameters that can be done by measuring lung function tests. The analogy "if we have BP, treatment will be monitored by measuring it through a sphygmomanometer. Same with diabetes, it is measured by a glucometer. Like this, the guidelines for Asthma, COPD, ILD, and various lung ailments are based on measurements obtained by doing various lung function tests. Usually, it is seen that patients of these ailments are given treatments just by looking at their symptoms by which disease is not under control, and patients can suffer from attacks. Sometimes loss of lung functions is permanent. Hence it is crucial to manage these cases by periodically doing the test as per the indications of the diseases. Lung function tests can be used to:
■ Compare your lung function with ideal standard values.
■ Measure the effect of chronic obstructive or restrictive diseases.
■ Monitor early changes and the need for a change in treatment.■ To check medicine response (bronchodilator).
■ Show whether exposure to substances in your home or workplace may have harmed your lungs.■ Determine your ability to tolerate surgery and medical procedures. To get the most accurate results from your breathing tests:
■ Do not smoke for at least 1 hour before the test.
■ Do not drink alcohol for at least 4 hours before the test.
■ Do not exercise heavily for at least 30 minutes before the test.
■ Do not wear tight clothing that makes it difficult to take a deep breath.
■ Do not eat a large meal within 2 hours before the test.
■ Ask your health care provider if there are any medicines that you should not take on the day of your
Various lung functions tests which can monitor lung functions are
1) SPIROMETRY: Spirometry is one of the most commonly ordered tests of your lung function. The spirometer measures how much air you can breathe into your lungs and how much air you can quickly blow out of your lungs. This test is done by having you take in a deep breath and then blow out all of the air as fast as you can.
2) DIFFUSING LUNG CAPACITY OF THE LUNGS FOR CARBON MONOXIDE(DLCO) :
Diffusion tests determine how well the oxygen in the air you breathe moves from your lungs into your blood. Like spirometry, this test is done by having you breathe into a mouthpiece connected to a machine. You will be asked to empty your lungs by gently breathing out as much air as you can. Then you will breathe in a quick(but deep breath), hold your breath for 10 seconds, and then breathe out as instructed. You will do the test several times. It usually takes about 30 minutes to complete this test.
3) BODY PLETHYSMOGRAPHY: Body plethysmography is a test to determine how much air is in your lungs after taking a deep breath and how much air is left in your lungs after breathing out as much as you can. Measuring the total amount of air your lungs can hold and the amount of air left in your lungs after you breathe out gives your healthcare provider information about how well your lungs are working and helps guide your treatment.
4) 6 -MINUTE WALK TEST: This test measures the distance a patient can quickly walk on a flat, hard surface in 6minutes (the 6MWD). It also shows if the level of oxygen falls on walking as happens in Covid.
5) IMPULSE OSCILLOMETRY: Impulse oscillometry (IOS) is a much simpler, noninvasive assessment technique of airway resistance and reactance. It is effort-independent, requires minimal patient cooperation and is suitable for use in both children and adults, can be performed in tidal breathing, and can distinguish between the degree of obstruction in central and peripheral airways
6) ATRIAL BLOOD GAS MONITORING: A blood gas test provides a precise measurement of your body's oxygen and carbon dioxide levels. This can help your doctor determine how well your lungs and kidneys are working. This test is most commonly used in the hospital setting to assess the management of acutely ill patients.
7) SKIN PRICK ALLERGIC TEST: A skin prick test, also called a puncture or scratch test, checks for immediate allergic reactions to as many as 50 different substances at once. This test is usually done to identify allergies to pollen, pet dander, dust and food.
8) AIR TRAVEL FITNESS TEST: Nowadays post covid airlines are very particular to screening passengers who use wheelchairs because of increasing mid-air emergencies which force an aeroplane to make emergency landing causing them colossal costs. As per rule, all passengers who use wheelchairs must produce air travel fitness tests, especially if they require supplemental oxygen. Before embarking on air travel, a fitness test can be done on the ground simulating flight conditions at high altitudes.
9) FRACTION OF EXHALED NITRIC OXIDE ( FeNO ): This test diagnoses if you have allergic bronchial asthma and if you will respond to an inhaled corticosteroid inhaler.
10) POLYSOMNOGRAPHY: It is done to test if you have an obstruction during breathing at night called sleep apnoea. This test should be done on obese patients who are habitual loud snorers having excessive daytime sleepiness.
What are the expected results for lung function tests?
Because Everyone's body and lungs are different sizes, expected results differ from person to person. For instance, taller people and males tend to have larger lungs, whereas shorter people and females have smaller lungs. It is usual for your lung function to fall slightly as you age. These standards that your healthcare provider uses are based on your height, age, and sex at birth. These numbers are called the "predicted values". Your measured values will be compared to these predicted values. Thus Lung Function tests are basic tests to diagnose & manage various Respiratory Diseases. If they are done early, they can detect lung ailments early to treat them better.
( The author is National Secretary of Indian Chest Society & ChiefPulmonologist & Director at Getwell Hospital and Research Institute, Dhantoli, Nagpur. For appointment contact M – 8767118507 )