How Is Asthma Diagnosed?

Asthma is a chronic respiratory disease characterized by the inflammation and narrowing of the airways, leading to symptoms such as shortness of breath, wheezing, coughing, and chest tightness. It affects a significant number of individuals worldwide, with an estimated 226 million people living with asthma.

To diagnose asthma, a thorough medical evaluation is conducted, which involves a physical examination, review of medical history, and diagnostic tests. Lung function tests, including spirometry, are commonly performed to assess lung capacity and airflow and provide an accurate diagnosis and evaluation of asthma severity.

While primary care providers and pediatricians often diagnose asthma, specialists such as allergists and pulmonologists are also qualified to diagnose and manage asthma and other respiratory conditions.

If you experience symptoms suggestive of asthma, it is crucial to seek medical attention from a healthcare professional. Asthma is a chronic condition that typically requires ongoing treatment. Obtaining an early diagnosis allows for the initiation of appropriate treatments to control symptoms and reduce the risk of complications associated with asthma.

Diagnostic Criteria

The diagnostic criteria for asthma involve a comprehensive assessment of symptoms, medical history, physical examination findings, and lung function tests. Two commonly used criteria are the Global Initiative for Asthma (GINA) criteria and the National Asthma Education and Prevention Program (NAEPP) guidelines.

According to the GINA criteria, the diagnosis of asthma is based on the following several key aspects.

• Symptoms: Presence of typical asthma symptoms, including coughing, wheezing, shortness of breath, and chest tightness that vary in severity and frequency over time.
• Documented variation in lung function: Demonstrated fluctuations in lung function, assessed through repeated lung function tests, indicating changes in breathing and lung capacity.
• Airway hyperresponsiveness: Excessive narrowing of the airways in response to triggers such as exercise or cold air, assessed through bronchial challenge tests.
• Exclusion of alternative diagnoses: Ruling out other conditions that could cause similar symptoms, such as heart failure, COPD, or bronchiectasis.

These diagnostic criteria help healthcare providers establish a diagnosis of asthma and differentiate it from other respiratory conditions. By considering symptoms, lung function tests, airway responsiveness, and ruling out alternative diagnoses, a more accurate diagnosis can be made to guide appropriate management and treatment strategies.

Medical History

During a thorough evaluation of your medical history, your healthcare provider will consider various factors to help diagnose or rule out asthma. These factors may include:

• Symptoms: Your provider will inquire about the nature of your symptoms, including their onset, frequency, duration, and any specific triggers or aggravating factors. You will be asked about activities, environmental conditions (such as cold air or pollen exposure), and other potential triggers like exercise or cigarette smoke.
• Medical conditions: It is important to disclose any past or current medical conditions you have experienced. Certain conditions, such as allergic rhinitis or chronic obstructive pulmonary disease (COPD), can increase the likelihood of developing asthma or exhibit symptoms similar to asthma.
• Medication use: Your healthcare provider will inquire about the medications you are currently taking, as some medications, such as beta-blockers or non-steroidal anti-inflammatory drugs (NSAIDs), can potentially worsen asthma symptoms.
• Family history: Providing information about your family’s medical history, specifically regarding asthma or allergies, is crucial. Asthma has a higher risk of occurrence in individuals with a family history of these conditions.
• Environmental exposures: Your healthcare provider will explore potential exposure to lung irritants and allergens in your home and work environments. Discussing any relevant exposures, such as dust, chemicals, or specific allergens, can aid in the diagnostic process.

Physical Examination

As part of the diagnostic process, your healthcare provider will conduct a physical examination to assess for signs and symptoms of asthma. During the examination, they will listen to your lungs using a stethoscope while you breathe. This allows them to detect any abnormal sounds such as wheezing or decreased breath sounds.

Additionally, your healthcare provider will evaluate your respiratory rate, observing for any signs of rapid or shallow breathing. They may also use a pulse oximeter, a device placed on your finger, to measure the oxygen saturation level in your blood. This helps assess the efficiency of your breathing and oxygen exchange.

Lung Function Tests

Lung function tests, or pulmonary function tests, measure different aspects of your respiratory health to confirm or rule out asthma. These tests include spirometry, peak flow meter test, fractional exhaled nitric oxide (FeNO) test, and bronchial provocation Tests.

Spirometry

Spirometry is a non-invasive test that measures lung function by assessing the amount of air you can breathe in and out and how quickly you can exhale. The test involves taking a deep breath and exhaling forcefully and rapidly into a spirometer machine. The results of spirometry include the following parameters:

• Forced Vital Capacity (FVC): This measures the total amount of air you can forcefully exhale after taking a deep breath.
• Forced Expiratory Volume in 1 second (FEV1): This measures the amount of air you can exhale in the first second of forced exhalation.

Your healthcare provider will compare your spirometry results to the expected values for individuals of similar age, gender, height, and race. In asthma, the FEV1 measurement may be lower than the average expected value.

The results obtained from spirometry can also be used to calculate the FEV1/FVC ratio. This ratio represents the percentage of your lung capacity that you can exhale in one second. For children, a low FEV1/FVC ratio is considered less than 85%, while for adults, it is considered less than 70%.

By analyzing spirometry results, your healthcare provider can assess the severity of airflow limitation and help confirm a diagnosis of asthma.

Peak Flow Meter

A peak flow meter is a handheld device used to measure the maximum airflow rate during a forceful exhale. During a peak flow meter test, you will take a deep breath and exhale forcefully into the device. The meter then measures the speed of your exhale, providing a score that can indicate whether your airways are narrowing.

The peak flow meter scores are categorized into three zones:

1. Green zone: If you can exhale at 80-100% of your usual peak flow rate, it indicates that your asthma is currently under control.

2. Yellow zone: If you can exhale at 50-80% of your usual peak flow rate, you are in the cautionary range. It is important to take action and seek appropriate medical attention to prevent worsening symptoms.

3. Red zone: If you exhale at 50% or less of your usual peak flow rate, you are in the medical alert range. It is crucial to seek immediate medical attention as your asthma may be severely compromised.

It’s important to note that individual results can vary depending on technique and other factors. To obtain the most accurate results, it is recommended to regularly monitor your peak flow and establish a baseline for your normal values. This helps you identify any significant deviations from your usual respiratory function and allows for timely intervention. Regular peak flow monitoring is a valuable tool in managing asthma and monitoring its control over time.

FeNO Test

The fractional exhaled nitric oxide (FeNO) test is a diagnostic tool used to measure the level of exhaled nitric oxide in your breath. Nitric oxide serves as a marker for a specific type of airway inflammation.

During the FeNO test, you will exhale slowly and steadily into a device that measures the concentration of nitric oxide in your breath. Inflammation of the airways, a characteristic feature of asthma, leads to increased production of nitric oxide. Higher levels of nitric oxide indicate greater airway inflammation, which is often seen in conditions like asthma.

The FeNO test is particularly useful in diagnosing a specific subtype of asthma called eosinophilic asthma. This subtype is characterized by elevated levels of eosinophils, a type of white blood cell associated with allergic inflammation. By measuring nitric oxide levels, the FeNO test helps identify the presence and degree of airway inflammation associated with eosinophilic asthma.

The FeNO test plays an important role in asthma management, as it provides valuable information about the level of airway inflammation. This information helps healthcare providers determine the most appropriate treatment strategies and monitor the effectiveness of asthma therapies.

Bronchial Provocation Tests

A bronchial provocation test, also known as a methacholine challenge test, is a diagnostic procedure used to assess the reactivity or sensitivity of your airways.

During the test, you will first undergo a baseline spirometry test. This involves breathing into a spirometer to measure your lung function and establish a baseline result. Following the baseline measurement, you will receive small doses of methacholine, a medication that can induce airway narrowing.

After each dose of methacholine, spirometry is repeated to assess how your airways respond to the medication. If there is a reduction of 20% or more in your breathing ability compared to the baseline measurement, it indicates a positive test result. This indicates that your airways are reactive and more sensitive, which is often seen in individuals with asthma.

The bronchial provocation test helps in confirming a diagnosis of asthma by demonstrating the responsiveness of your airways to specific triggers. It is a safe and controlled procedure performed under medical supervision to evaluate the presence of airway hyperresponsiveness.

Allergy Testing

Allergy testing may be recommended by your healthcare provider if you experience asthma symptoms that are triggered by exposure to allergens. The purpose of allergy testing is to identify specific allergens that may contribute to your asthma symptoms. Some common allergy tests include:

• Skin prick test: During this test, a small amount of suspected allergens are placed on your skin, typically on your forearm or back. The skin is then pricked or scratched to allow the allergen to enter. If you are allergic to the specific substance, you may develop a small raised bump or redness at the site of the test.
• Immunoglobulin E (IgE) test: This is a blood test that measures the levels of immunoglobulin E (IgE) antibodies in your blood. IgE is produced by the immune system in response to allergens. High levels of IgE can indicate an allergic reaction to certain airborne allergens, such as mold, pet dander, or pollen.

These allergy tests help identify the specific allergens that may be triggering or exacerbating your asthma symptoms. By identifying these triggers, you can take steps to avoid or minimize your exposure to them, which can help in managing your asthma effectively. Allergy testing is typically performed by allergists or immunologists who specialize in diagnosing and treating allergies and related conditions.

Imaging Tests

Imaging tests are not typically used as primary diagnostic tools for asthma, but they may be ordered by healthcare providers to rule out other conditions that can cause asthma-like symptoms or to evaluate certain cases. Some imaging tests that may be used in these situations include:

• Chest X-ray: A chest X-ray can help assess the condition of the lungs and rule out other lung diseases that may present similar symptoms to asthma.
• Acid reflux test: Acid reflux can sometimes trigger or worsen asthma symptoms. If there is a suspicion of acid reflux as a contributing factor to asthma symptoms, a healthcare provider may order tests to evaluate the presence and severity of acid reflux, such as a pH probe test or an upper endoscopy.
• Sinus imaging: Chronic sinusitis can be associated with asthma or contribute to asthma symptoms. In cases where sinusitis is suspected, imaging tests like a sinus X-ray or a sinus CT scan may be ordered to assess the sinus passages.

Screening for Related Conditions

To make an accurate diagnosis of asthma, healthcare providers must carefully evaluate and rule out other conditions that can present with similar symptoms. Some of the conditions they may consider include:

1. Chronic obstructive pulmonary disease (COPD): COPD is a group of lung diseases, including chronic bronchitis and emphysema, which can cause symptoms similar to asthma such as coughing, wheezing, and shortness of breath.

2. Bronchiectasis: This condition involves the permanent widening and damage of the airways, leading to symptoms resembling asthma, such as chronic cough, wheezing, and difficulty clearing mucus.

3. Vocal cord dysfunction (VCD): VCD is a condition in which the muscles around the vocal cords tighten, leading to breathing difficulties and wheezing that can be mistaken for asthma.

4. Congestive heart failure (CHF): CHF is a heart condition that can cause symptoms similar to asthma, including shortness of breath and wheezing. However, CHF is usually accompanied by other symptoms such as swelling in the legs and fatigue.

5. Gastroesophageal reflux disease (GERD): GERD is a digestive disorder where stomach acid flows back into the esophagus, causing symptoms such as chest pain, coughing, and wheezing that can mimic asthma. Symptoms of GERD often worsen after eating or when lying down.

Additionally, healthcare providers may also screen for comorbid conditions, which are conditions that commonly coexist with asthma. These may include:

– Obstructive sleep apnea

– Allergies

– Rhinitis (nasal inflammation)

– Obesity

– Anxiety and depression

By carefully evaluating and ruling out these conditions, healthcare providers can make a more accurate diagnosis of asthma and provide appropriate treatment and management strategies.

A Quick Review

Your doctor will need to look at your symptoms, medical history, and test findings to determine if you have asthma. Asthma may be diagnosed with the use of pulmonary function tests like spirometry and FeNO testing. Bloodwork, scans, and allergy tests are other options.

Your healthcare professional should rule out illnesses including COPD, bronchiectasis, and vocal cord dysfunction that can cause symptoms similar to asthma. Allergies, gastroesophageal reflux disease, and obstructive sleep apnea are among disorders that may be screened for in an individual with asthma.