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Asthma in children and adolescents - Diagnosis

Description

An in-depth report on how asthma is diagnosed, treated, and managed in children and adolescents.

Diagnosis:

Pulmonary Function Tests

If symptoms and a patient's history strongly suggest asthma, the doctor will usually perform tests known as pulmonary function tests to confirm the diagnosis and determine the severity of the disease.

Using a spirometer, an instrument that measures the air taken into and exhaled from the lungs, the doctor will determine several values:

Vital capacity (VC), the maximum volume of air that can be inhaled or exhaled.
Peak expiratory flow rate (PEFR), commonly called the peak flow rate, the maximum flow rate that can be generated during a forced exhalation.
Forced expiratory volume (FEV1), the maximum volume of air expired in 1 second.

If the airways are obstructed, these measurements will fall. Depending on the results, the doctor will take the following steps:

If measurements fall, the doctor typically asks the patient to inhale a bronchodilator. This drug is used in asthma to open the air passages. The measurements are taken again. If the measurements are more normal, the drug has most likely cleared the airways, and a diagnosis of asthma is strongly suspected.
If measurement results fail to show airway obstruction, but asthma is still suspected, the doctor may perform a challenge test. It involves administering a specific drug (histamine or methacholine) that usually increases airway resistance only when asthma is present.

Allergy Tests

The patient may receive skin or blood allergy tests, particularly if a specific allergen is suspected and available for testing. Allergy skin tests help diagnose for allergic asthma, although they are not recommended for people with year-round asthma.

One of the most common methods of allergy testing is the scratch test or skin prick test. The test involves placing a small amount of the suspected allergy-causing substance (allergen) on the skin (usually the forearm, upper arm, or the back), then scratching or pricking the skin so that the allergen is introduced under the skin surface. The skin is observed closely for signs of a reaction, which usually includes swelling and redness of the site. With this test, several suspected allergens can be tested at the same time, and results are usually available within about 20 minutes.

Resources

www.lungusa.org -- The American Lung Association
www.acaai.org -- American College of Allergy, Asthma & Immunology
www.aaaai.org -- American Academy of Allergy, Asthma, and Immunology
www.nhlbi.nih.gov -- National Heart, Lung, and Blood Institute
www.aafa.org -- Asthma and Allergy Foundation of America
www.aanma.org -- Allergy and Asthma Network, Mothers of Asthmatics

References

American Lung Association Asthma Clinical Research Centers, Peters SP, Anthonisen N, Castro M, Holbrook JT, Irvin CG, et al. Randomized comparison of strategies for reducing treatment in mild persistent asthma. N Engl J Med. 2007 May 17;356(20):2027-39.

Bateman E, Nelson H, Bousquet J, Kral K, Sutton L, Ortega H, Yancey S. Meta-analysis: effects of adding salmeterol to inhaled corticosteroids on serious asthma-related events. Ann Intern Med. 2008 Jul 1;149(1):33-42. Epub 2008 Jun 3.

Castro-Rodriguez JA, Rodrigo GJ. Efficacy of inhaled corticosteroids in infants and preschoolers with recurrent wheezing and asthma: a systematic review with meta-analysis. Pediatrics. 2009 Mar;123(3):e519-25.

Fanta CH. Asthma. N Engl J Med. 2009 Mar 5;360(10):1002-14.

Greer FR, Sicherer SH, Burks AW; American Academy of Pediatrics Committee on Nutrition; American Academy of Pediatrics Section on Allergy and Immunology. Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics. 2008 Jan;121(1):183-91.

Kukkonen K, Savilahti E, Haahtela T, Juntunen-Backman K, Korpela R, Poussa T, et al. Probiotics and prebiotic galacto-oligosaccharides in the prevention of allergic diseases: a randomized, double-blind, placebo-controlled trial. J Allergy Clin Immunol. 2007 Jan;119(1):192-8. Epub 2006 Oct 23.

National Asthma Education and Prevention Program Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Rockville, MD. National Heart, Lung, and Blood Institute, US Dept of Health and Human Services; 2007. NIH publications 08-4051.

Stern DA, Morgan WJ, Halonen M, Wright AL, Martinez FD. Wheezing and bronchial hyper-responsiveness in early childhood as predictors of newly diagnosed asthma in early adulthood: a longitudinal birth-cohort study. Lancet. 2008 Sep 20;372(9643):1058-64.

Vliagoftis H, Kouranos VD, Betsi GI, Falagas ME. Probiotics for the treatment of allergic rhinitis and asthma: systematic review of randomized controlled trials. Ann Allergy Asthma Immunol. 2008 Dec;101(6):570-9.

Reviewed last on: 6/1/2009
Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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