Asthma is a chronic lung disease that causes episodes of difficulty in breathing. It can affect people of all ages. Early detection and subsequently diagnosing asthma by appropriate investigation is important to ensure early treatment and to prevent severe asthma attack. Late detection may delay early care and putting patients at risk for asthma complication, being warded or even facing a life-threatening asthma attack.
How do doctors diagnose asthma in adult?
Doctor can diagnose asthma based on :
- Presence of symptoms suggestive of asthma
- Physical examination to detect signs of asthma, however there may be no signs when there is no asthma attack. Presense of eczema may be seen in some patients
- Appropriate investigation to assist in the diagnosis of asthma
What tests or investigations to assist in making diagnosis for asthma?
If the patient presents with asthma symptoms for the first time, the doctor has to elicit detail history and examination to detect asthma and perform tests to search and rule out the symptoms are not caused by any other ailments.
Investigations which are helpful to assist in making a diagnosis and to assess the severity of asthma include:
Tests to measure lung function
These tests can determine how much air moves in and out as the patient breathe. Lung function tests often done before and after taking a bronchodilator such as ventolin inhaler, to open up the airways. If the patient’s lung function improves with the use of a bronchodilator, it is likely that the patient has asthma. These tests may incorporate:
This device measures the narrowing of the airways by checking how much air the patient can exhale after a deep breath and how fast the patient can breathe out. The test may be done before and after the patients take an inhaled medication to assess the reversibility of the airways. A reversibility of 12-15% or 200mls post-bronchodilator makes a diagnose of asthma.
- Peak flow
A peak flow meter is a simple device that measures how hard the patient can breathe air out. If it is lower than the usual peak flow readings (which is compared to a normogram), signet indicates that the lungs may not be working properly and that the patient’s asthma may be getting worse. The doctor will advise on how to deal with low peak flow readings. Peak flow meter is another way of measuring the patient’s exhalation strength during an asthma attack. PEF is also used to assess the response to the copy. The improvement in PEF measurement (increase) means that response to treatment is good.
A painless probe, called a pulse oximeter, will be placed on the fingertip to measure the amount of oxygen in the bloodstream especially during an acute asthma attack.
Doctors may recommend other tests if they need more information to make a diagnosis or to rule out other causes of breathing problems. Tests which may be useful include :
- Imaging tests
A chest radiograph is usually done to seek for complications of asthma or presence of lung infection. A high-resolution computerized tomography (HRCT) scan of the lungs and nose cavities is only done if other illnesses are suspected. It is not routinely done in asthma
- Electrocardiogram ECG
It can help to find out whether other diseases (for example underlying heart disease) which maybe causing the symptoms.
- Blood tests
There is no blood test than can locate the cause of asthma. Blood may be checked for signs of an infection that might be contributing to the asthma attack.
In severe asthma attacks, it may be necessary to take blood sample from an artery to determine exactly how much oxygen and carbon dioxide are present in the patient’s body.
Asthma is a chronic lung disease that can cause episodic symptoms which can interfere with daily activities or even can lead to fatal attack. Appropriate investigation and early diagnosis of asthma can ensure early and proper treatment in order to prevent both short-term and long-term complications of asthma. Asthmatics may be lead a normal life if their symptoms are well controlled.
- National Heart, Lung, and Blood Institute. What is asthma? http://www.nhlbi.nih.gov/health/health-topics/topics/asthma/. Accessed May 6, 2013.
- McPhee SJ, et al. Current Medical Diagnosis & Treatment 2012. 51st ed. New York, N.Y.:The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/content.aspx?aID=2740. Accessed May 6, 2013.
- Parker MJ. Asthma. Otolaryngologic Clinics of North America. 2011;44:667.
- Asthma and Allergy Foundation of America. Asthma overview – diagnosis. http://www.aafa.org/display.cfm?id=8&cont=7. Accessed May 6, 2013.
- Ronald B. George, Richard W. Light, Richard A. Matthay, Michael A. Matthay. Asthma. In Chest Medicine: Essentials Of Pulmonary And Critical Care Medicine May 2005, 5th edition.
- Ministry Of Health Malaysia. Clinical Practice Guidelines For Management Of Adult Asthma 2002.
- Global Strategy for Asthma Management and Prevention: Global Initiative for Asthma (GINA) (Updated 2012)
How do doctors diagnose asthma in adults? (Investigation) (Quiz)
- Early recognition of asthma by appropriate investigation is important to ensure early diagnosis and treatment in order to prevent asthma complications.
- Not sure
- When the patient presents with asthma symptoms for the first time, it is not useful for the doctor to perform tests to confirm the diagnosis of asthma.
- Not sure
- If the patient’s lung function improves with use of a bronchodilator, it is unlikely that the patients have asthma.
- Not sure
- A chest X-ray is useful (if indicated) to identify any underlying lung infection that can cause or aggravate the asthma symptoms.
- Not sure
- Blood tests may be checked for signs of infection that might be contributing to the asthma attack.
- Not sure