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How To Test For Asthma

What Are The Consequences Of Overdiagnosis

Using Spirometry to Test for Asthma

One of the problems of misdiagnosis is that there may be an alternative diagnosis that is not made in a timely fashion. Some of the final diagnoses in the study by Aaronet al. , such as ischaemic heart disease, subglottic stenosis and pulmonary hypertension, were serious and could lead to patient harm if unrecognised. In addition to this risk, patients are often on long-term inhaled therapy unnecessarily, leading both to potential side-effects and significant ongoing healthcare costs as these drugs are likely to be issued for many years after a diagnosis of asthma. In the past, many mild asthma patients were simply on an as required SABA inhaler, but increasingly this is discouraged with daily ICS therapy recommended for all but a few . This represents a burden to the patient and could conceivably cause side-effects such as an increased risk of adrenal suppression, diabetes, cataract formation and pneumonia . If the wrong diagnosis is made patients are also likely to remain symptomatic, and potentially have their asthma treatment stepped up, adding to both the cost and the potential for side-effects.

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Box 4 Key Messages For The Diagnosis Of Asthma In Adults

  • The diagnosis of asthma should be suspected in patients with recurrent cough, wheeze and dyspnea in whom no alternative diagnosis can be found and should be confirmed by an objective measurement of lung function or, if normal, by tests for bronchial hyperresponsiveness .

  • A clinical diagnosis of asthma should be prompted by symptoms such as episodic breathlessness, wheezing, cough, sputum and chest tightness .

  • Measurements of lung function by spirometry or peak expiratory flow provide an assessment of the severity of airflow limitation, its reversibility and its variability, and can be used to confirm the diagnosis of asthma .

  • Measurements of allergic status can help to identify risk factors that cause asthma symptoms in individual patients .

  • Because the obstruction observed in asthma is variable, it is possible for the spirometry results to be normal for a patient who has asthma. Options to confirm asthma include bronchial challenge tests, serial peak flow monitoring and measurements of inflammation .

  • For patients with symptoms consistent with asthma who have normal lung function, measurement of airway responsiveness may help to establish the diagnosis .

  • Challenge testing is potentially useful in patients with typical symptoms but normal spirometry results or atypical symptoms or possible occupational asthma .

What Information The Test Provides

The first thing you need to understand is the type of information that pulmonary function tests provide. The most common things that they assess include:

  • Blockage of airways
  • In what ways lung diseases may be obstructing breathing
  • The sensitivity of the airways
  • If current medications are effective or not
  • How the functioning of your lungs has changed over a certain period

Best of all, since it is a simple test. It can be performed on the vast majority of adults and children aged five or older.

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Assessing The Work Environment

It is important to take a detailed work history of the workers present and past employment. Sometimes it is hard to pin point the exact chemical or material that is causing the problem so many questions should be asked about what the workers uses at work as well as the workplace in general. Sometimes an occupational hygienist may visit the workplace to help identify hazardous chemicals. It is also important to see if any other workers are having the same symptoms. Symptoms among several workers in a specific area or may give a clue as to what is causing the problem.

How Is Family And Symptom History Used In The Diagnosis Of Asthma

Exhaled Nitrous Oxide Adjunct Test Diagnoses Asthma ...

Your doctor may ask questions about your family and symptom history:

  • When did you first notice symptoms?
  • How would you describe them? Cough? Trouble catching your breath? Noisy breathing?
  • How often do they happen?
  • How long do they last?
  • What makes them better or worse?
  • Do you or anyone in your family have a history of asthma, environmental or food allergies, rhinitis, eczema , bronchitis, or colds that linger for months instead of days?
  • Does anyone in your family, home or workplace smoke?
  • Do you cough or have problems catching your breath when exercising?
  • Do breathing problems disturb your sleep?
  • What is your home, school, and work environment like?;

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Why Does It Occur

Underdiagnosis may be due to medical professionals failing to recognise the disease, and perhaps attributing symptoms to obesity, deconditioning, cardiac disease or other causes. The patient may appear well with no abnormality on examination and if objective tests for asthma are carried out, particularly as a one off or when the patient is already on treatment, they may be falsely reassuring or misunderstood by the treating physician as excluding asthma. One might speculate that because asthma is so prevalent, patients are less likely to be referred to specialists for confirmation of the diagnosis when it is unclear, whereas patients with suspected diseases that are less familiar may be more likely to be referred.

Other Tests You May Need If You Have Asthma

Even if your lung function tests are normal, your doctor may order other tests to see what could be causing your asthma symptoms.

  • Gas and diffusion tests can measure how well your blood absorbs oxygen and other gases from the air you breathe. You breathe in a small amount of a gas, hold your breath, then blow out. The gas you exhale is analyzed to see how much your blood has absorbed.
  • X-rays may tell if there are any other problems with your lungs, or if asthma is causing your symptoms. High-energy radiation creates a picture of your lungs. You may be asked to briefly hold your breath while you stand in front of the X-ray machine.

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Comorbidities And Risk Factors

Both for adults and children, the detection of potentially modifiable risk factors for exacerbations may be useful in asthma monitoring and includes the exposure to specific allergens, smoking, high SABA use, poor adherence to therapy and incorrect inhaler technique. As already mentioned, GINA guidelines state that a previous sever exacerbation in last 12 months and a history of access into an intensive care or intubation are major independent risk factors for exacerbations .

Moreover, the asthma monitoring cannot be separated from an early identification and management of associated comorbidities .

Fractional Exhaled Nitric Oxide Test

How is asthma diagnosed?

If after routine testing, including spirometry and bronchodilator responsiveness, an asthma diagnosis isn’t certain, a FeNO test may be performed, according to National Institutes of Health recommendations for asthma management. This test determines the presence of inflammation in the lungs and is performed using a portable device that measures the level of nitric oxide in parts per billion in exhaled air.

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There Are Four Key Symptoms That You Should Monitor To Help You Keep Your Asthma Under Control:

  • Daytime SymptomsHow often do you have asthma symptoms during the day, such as coughing, wheezing, chest tightness or shortness of breath?
  • Nighttime SymptomsDo you wake up at night with asthma symptoms, such as coughing, wheezing, chest tightness or shortness of breath?
  • Quick-Relief or Rescue Inhaler UseHow often do you use your quick-relief or rescue inhaler to relieve asthma symptoms?
  • Activity LevelDo you have difficulty performing normal activities, such as walking, climbing stairs, daily chores or playing with the kids?

How To Tell You Have Asthma

In this section: Diagnosis and Lung Testing | How To Tell You Have Asthma | Your Healthcare Team

Asthma is a complex disease to diagnose, and only a healthcare professional is able to make a proper diagnosis.

If you are concerned that you may have asthma, contact your healthcare provider. In order to confirm an asthma diagnosis, your healthcare provider will take into account your medical and family history, allergies, and conduct lung function testing such as spirometry.

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What Happens During A Spirometry Test

Youll be seated during the test and a soft clip will be placed on your nose to stop air escaping from it.

The tester will explain what you need to do, and you may be asked to have a few practise attempts first.

When youre ready for the test, youll be asked to:

  • inhale fully, so your lungs are completely filled with air
  • close your lips tightly around the mouthpiece
  • exhale as quickly and forcefully as you can, making sure you empty your lungs fully

This will normally need to be repeated at least 3 times to ensure a reliable result.

Sometimes, the test may need to be repeated around 15 minutes after;taking some inhaled bronchodilator medicine.

This can show if you have a lung condition that responds to these medicines.

Overall, your appointment;should last around 30 to 90 minutes. Youll be able to go home soon after the tests have finished and return to your normal activities.

Types Of Lung Function Tests

Take The 30 Second Asthma Test

Lung function tests are often done before and after inhaling a medicine known as a bronchodilator , which opens your airways. If your lung function improves a lot after a bronchodilator, you probably have asthma.

Most lung function tests require you to exhale or inhale using a device or a mouthpiece connected to a device. They are simple tests that are often done in the doctors office. Your doctor may ask you to stop taking certain medicines before your appointment.

Spirometry. This is the recommended test to confirm asthma. During this test, you breathe into a mouthpiece thats connected to a device, called a spirometer, or to a laptop. It measures the amount of air youre able to breathe in and out and its rate of flow. You will take a deep breath and then exhale forcefully.;

Peak flow meter.;This test uses a peak flow meter. Its a small, handheld device that you breathe into to measure the rate at which you can force air out of your lungs. During the test, you breathe in as deeply as you can and then blow into the device as hard and fast as possible. If youre diagnosed with asthma, you can use a peak flow meter at home to help track your condition. But a peak flow meter cannot be used to diagnose asthma.

These lung function tests are some of the most common types used. There are also other types of lung function tests your doctor may use to diagnose and manage your asthma, depending on age, symptoms, medical history and more. ;

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What Are The Consequences

Asthma that is undiagnosed is also untreated, and this is likely to result in patients with ongoing symptoms. Patients may avoid exercise, may miss work and be less productive, and their quality of sleep and overall quality of life are likely to be adversely affected. These patients are likely to have unsuppressed airway inflammation and eosinophilic airway inflammation is associated with more asthma exacerbations , which may lead to the requirement for OCS and potentially hospitalisation.

It is possible that patients may also die of asthma prior to diagnosis, or on their first presentation of asthma. The UK national review of asthma deaths examined 195 deaths attributed to asthma between 2012 and 2013 . Importantly, 38% of these patients had four or fewer inhalers with a steroid component issued in the previous year, indicating that undertreatment was a probable important factor in their deaths. Almost half of the patients that died of asthma were being managed as mild or moderate asthma. While this does not directly deal with underdiagnosis, it is an important reminder that even in the developed world undertreatment of asthma remains a problem.

Restrictive Pattern On Spirometry

With a restrictive spirometry pattern your FVC is less than the predicted value for your age, sex and size. This is caused by various conditions that affect the lung tissue itself, or affect the capacity of the lungs to expand and hold a normal amount of air. Conditions that cause scarring of the lungs give restrictive patterns on spirometry. Some physical deformities that restrict the expansion of the lungs can also cause a restrictive defect. Your FEV1 is also reduced but this is in proportion to the reduced FVC. So, with a restrictive pattern the ratio of FEV1/FVC is normal.

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Keep A Record Of Asthma Symptoms

If you or a family member have breathing difficulties, keep a diary of symptoms to discuss with your doctor. You could also make a video or audio recording of the wheezing, using your mobile phone.The diary may include:

  • when the symptoms occur such as during the day or worse at night
  • how bad the symptoms are and how often they happen
  • how long the symptoms remain and whether they change with time
  • whether the symptoms are worse after exercise, playing, laughing or after an infection
  • whether the symptoms are worse after exposure to animals, pollens;or mould.

Understanding Spirometry And Narrow Airways

How do we test for asthma? Part 1

Think of a 5-lane motorway that has been reduced to 3 lanes due to roadworks. The traffic will take longer to travel through that stretch of motorway.

In the same way, if your airway is narrower than normal, it will take you longer to empty your lungs of air.

A spirometer records how much air you can breathe out in one second. That will be less if your airways are narrower than someone of your sex, age, height and ethnicity with healthy airways. It can also compare that result to how much air you breathed out, to measure how much your airways are blocked. In someone with healthy airways, at least 70% of the total air they breathe out would be breathed out in one second.

An example of a spirometry result for a hospital spirometer

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Tests Done To Evaluate Asthma & Copd

Sometimes, your doctor can be fairly certain whether or not you have asthma or COPD based on your symptoms and;physical;examination. Often, though, more information is needed to distinguish between asthma and other respiratory problems. After all, asthma is not the only medical problem that can lead to breathing difficulties. If there are doubt about your diagnosis, your;physician;may ask you to perform some tests that provide additional;information;regarding how well your lungs work or whether you have allergies. These are called pulmonary;function;tests or allergy tests.


The most commonly used pulmonary function test is called spirometry. Patients are asked to breathe in to fill their lungs, then blow out as fast and as completely as possible into a machine which measures how much and how fast they can exhale.

Post-bronchodilator spirometry

;Commonly, an asthmatic patient will be asked to repeat spirometry after inhaling a quick-reliever medicine, like albuterol. Patients with asthma typically show substantial improvements after inhaling such a medicine. Patients with other lung diseases often do not exhibit such immediate benefit.

Some additional Pulmonary Function Tests your doctor may order are diffusing capacity, a methacholine challenge, or an exercise challenge test. Your doctor may also order an;artificial;blood gas sample.

Allergy tests

What Is Included In An Asthma Test

This exam will include an inspection of the eyes, ears, nose, and throat, as well as possible lung X-rays.

Once the physical exam is complete, the doctor will test your lungs using a series of breathing tests. If your lungs are underperforming, they will determine whether the source of the problem is asthma or something else.

Its important to remember that there are different levels of asthma, so even if you are diagnosed, it may not be as severe as some other cases. Generally speaking, asthma severity ranges from 4 different levels:;

  • Intermittent;

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How To Perform A Pef

Before doing a home lung function test, to measure your PEF, remove any food, gum, and excess saliva from your mouth, as such obstructions could interfere with the efficiency of the test. Also check the peak flow meter for obstructions or foreign objects, then follow these eight simple steps to effectively perform the test.

  • Set your peak flow meter to zero, or the bottom of the scale.
  • Attach the mouthpiece to the peak flow meter.
  • Stand up to guarantee you get a deep breath. Stay standing and do not move throughout the test so your results are not affected by a change in position.
  • Take a deep breath in and place the peak flow meter mouthpiece closely and tightly around your lips. Do not put your tongue inside the mouthpiece.
  • Breathe out as forcefully as you can, using a huff-like motion, for no longer than one second.
  • Write down the reading on the gauge.
  • Place the peak flow meter back to zero before blowing again.
  • Repeat the blowing and recording process two more times. Go again if you cough or experience any other complications.;
  • After blowing into the peak flow meter a total of three times, record your highest value for the day. If instructed, also record the other readings.

    What Happens In A Spirometry Test

    FeNO Testing Can Be a Helpful Part of Asthma Management ...

    Spirometry is a painless test that can often be done in your doctors office or in a nearby clinic. The entire test usually takes less than 10 minutes, although sometimes it is repeated after taking a puffer medication.

    How to prepare for the test:

    • Do not smoke for one hour before test
    • Do not drink alcohol within four hours of test
    • Do not eat a large meal within two hours of test
    • Please wear loose clothing
    • Do not perform vigorous exercise within 30 minutes of test
    • If you are on puffer medications, you may be asked to not take them for a few hours before spirometry. Ask your doctor beforehand if this applies to you.

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