Brittle asthma
| Brittle asthma | |
|---|---|
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| Asthma (lungs) | |
| Prevention | Allergen avoidance and self-management approach |
Brittle asthma is a type of asthma distinguishable from other forms by recurrent, severe attacks.[1][2][3] There are two subtypes divided by symptoms: Type 1 and Type 2,[4] depending on the stability of the patient's maximum speed of expiration, or peak expiratory flow rate (PEFR). Type 1 is characterized by sustained, chronic variability of PEFR, while type 2 is distinguished by sudden unpredictable drops in PEFR where asthma symptoms are otherwise well controlled and the function of the lungs is not substantially impaired.[citation needed]
Brittle asthma is one of the "unstable" subtypes of "difficult asthma", a term used to characterize the less than 5% of asthma cases that do not respond to maximal inhaled treatment, including high doses of corticosteroids combined with additional therapies such as long-acting beta-2 agonists.[5][6]
Diagnosis
Types
The 2005 Oxford Textbook of Medicine distinguishes type 1 brittle asthma by "persistent daily chaotic variability in peak flow (usually greater than 40 per cent diurnal variation in PEFR more than 50 per cent of the time)", while type 2 is identified by "sporadic sudden falls in PEFR against a background of usually well-controlled asthma with normal or near normal lung function".[7] In both types, patients are subject to recurrent, severe attacks. The cardinal symptoms of an asthma attack are shortness of breath (dyspnea), wheezing, and chest tightness.[8] Individuals with type 1 suffer chronic attacks in spite of ongoing medical therapy, while those with type 2 experience sudden, acute and even potentially life-threatening attacks even though otherwise their asthma seems well managed.[9]
When first defined by Margaret Turner-Warwick in 1977, the term brittle asthma was used specifically to describe type 1, but as studies into the phenotype were conducted the second type was also distinguished.[10]
Treatment
In addition to any issues of treatment compliance, and maximised corticosteroids (inhaled or oral) and beta agonist, brittle asthma treatment also involves for type 1 additional subcutaneous injections of beta2 agonist and inhalation of long acting beta-adrenoceptor agonist,[11] whilst type 2 needs allergen avoidance and self-management approaches.[12] Since catastrophic attacks are unpredictable in type 2, patients may display identification of the issue, such as a MedicAlert bracelet, and carry an epinephrine autoinjector.[7]
Epidemiology
The condition is rare. 1999's Difficult Asthma estimates a prevalence of approximately 0.05% brittle asthma sufferers among the asthmatic population.[13] Though found in all ages, it is most commonly found in individuals between the ages of 18 and 55; it is present in both sexes, though type 1 has been diagnosed in three times as many women as men.[13] Hospitalization is more frequent for type 1 than type 2.[13]
References
- ^ Holgate, Stephen T.; Homer A. Boushey; Leonardo M. Fabbri, eds. (1999). Difficult asthma. Informa Health Care. p. 291. ISBN 1-85317-556-0.
- ^ Gupta D, Ayres JG (2001). "Brittle asthma: a separate clinical phenotype of asthma?". Indian J Chest Dis Allied Sci. 43 (1): 33–8. PMID 11370504.
- ^ Ayres JG, Jyothish D, Ninan T (March 2004). "Brittle asthma". Paediatr Respir Rev. 5 (1): 40–4. doi:10.1016/j.prrv.2003.09.003. PMID 15222953.
- ^ Ayres JG, Miles JF, Barnes PJ (April 1998). "Brittle asthma". Thorax. 53 (4): 315–21. doi:10.1136/thx.53.4.315. PMC 1745199. PMID 9741378.
- ^ Warrell, David A. (2005). Oxford textbook of medicine: Sections 18-33. Oxford Medical Publications. Vol. 3 (4th ed.). Oxford University Press. p. 1346. ISBN 0-19-856978-5.
- ^ Ogorodova LM, Selivanova PA, Gereng EA, Bogomiakov VS, Volkova LI, Pleshko RI (2008). "[Pathomorphological characteristics of unstable bronchial asthma (brittle phenotype)]". Ter. Arkh. (in Russian). 80 (3): 39–43. PMID 18441682.
- ^ a b Warrell, 1347.
- ^ Saunders (2005). "Asthma". In Homer A. Boushey Jr., M.D.; David B. Corry, M.D.; John V. Fahy, M.D.; Esteban G. Burchard, M.D.; Prescott G. Woodruff, M.D.; et al. (eds.). Mason: Murray & Nadel's Textbook of Respiratory Medicine (4th ed.). Elsevier.
- ^ Holgate et al., 292.
- ^ Waldron, Jill (2007). Asthma Care in the Community. Wiley-Interscience. p. 122. ISBN 978-0-470-03000-4.
- ^ Graziani E, Petroianni A, Terzano C (2004). "Brittle asthma". Eur Rev Med Pharmacol Sci. 8 (4): 135–8. PMID 15636398.
- ^ Toungoussova O, Foschino Barbaro MP, Esposito LM, et al. (June 2007). "Brittle asthma". Monaldi Arch Chest Dis. 67 (2): 102–5. doi:10.4081/monaldi.2007.497. PMID 17695694.
- ^ a b c Holgate et. al, 293.