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PROTOKOL 23 Asma Michael Schatz Overview  Asthma currently affects approximately 8% of pregnant women, making it probably  the most common potentially serious medical problem to compli­ cate pregnancy.  Although data have been conflicting, recent meta­analyses have suggested that  maternal asthma increases the risk of perinatal mortal­ ity, preeclampsia, preterm birth and low­birth­weight infants. More severe asthma is associated with increased risks,  while better­controlled asthma is associa
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  PROTOKOL 23 Asma Michael Schatz Overview Asthma currently affects approximately 8% of pregnant women, making it probably the most common potentially serious medical problem to compli- cate pregnancy. Although data have been conflicting, recent meta-analyses have suggested that maternal asthma increases the risk of perinatal mortal- ity, preeclampsia, preterm birthand low-birth-weight infants. More severe asthma is associated with increased risks, while better-controlled asthma is associated with decreased risks. Pathophysiology Asthma is an inflammatory disease of the airways that is associated with reversible airway obstruction and airway hyper-reactivity to a variety of stimuli. Although the cause of asthma is unknown, a number of clini- cal triggering factors can be identified, including viral infections, allergens, exercise, sinusitis, reflux, weather changes and stress. Airway obstruction in asthma can be produced by varying degrees of mucosal edema, bronchoconstriction, mucus plugging, and airway remod- eling. In acute asthma, thesechanges can lead to ventilation perfusion imbalance and hypoxia. Although early acute asthma is typically associated with hyperventilation and hypocapnea, progressive acute asthma can cause respiratory failure with associated carbon dioxide retention and acidosis. Diagnosis Many patients with asthma during pregnancy will already have a physician diagnosis of asthma. A new diagnosis of asthma is usually suspected on the basis of typical symptoms – wheezing, chest tightness, cough and associ- ated shortness of breath – which tend to be episodic or at least fluctuating in intensity and are typically worse at night. Identification of the character- istic triggers further supports the diagnosis. Wheezing may be present on auscultation of the lungs, but the absence of wheezing on auscultation does not exclude the diagnosis. The diagnosis is ideally confirmed by spirometry, which shows a reduced forced expiratory volume (FEV) 1 with an increasein FEV 1 of 12% or more after an inhaled short-acting bronchodilator. It is sometimes difficult to demonstrate reversible airway obstruction in patients with mild or intermittent asthma. Although methacholine challenge testing may be  considered in nonpregnant patients with normal pulmonary function to confirm asthma, such testing is not recommended during pregnancy. Thus, therapeutic trials of asthma therapy should gen- erally be used during pregnancy in patients with possible but unconfirmed asthma. Improvement with asthma therapy supports the diagnosis, which can then be confirmed postpartum with additional testing if necessary. The most common differential diagnosis is dyspnea of pregnancy, which may occur inearly pregnancy in approximately 70% of women. This dys- pnea is differentiated from asthma by its lack of association with cough, wheezing or airway obstruction. Another aspect of asthma diagnosis is an assessment of severity. Although more complicated severity schemes have been proposed, the most impor- tant determinationis whether the patient has intermittent versus persistent asthma. This distinction has both prognostic and therapeutic significance during pregnancy. Patients with intermittent asthma have short episodes less than three times per week, nocturnal symptoms less than three times a month, and normal pulmonary function between episodes. Patients with more frequent symptoms or who require daily asthma medications are con- sidered to have  persistent asthma . Asthma severity often changes during pregnancy; it can get either better or worse. Patients with more severe asthma prior to pregnancy are more likely to further worsenduring pregnancy. Since gestational asthma course in an individual woman is unpredictable, women with asthma must be followed particularly closely during pregnancy so that any change in course can be matched with an appropriate change in therapy. Management General Identifying and avoiding asthma triggers can lead to improved maternal well-being with less need for medications. In previously untested patients, in vitro (RAST, ELISA) tests should be performed to identify relevant allergens, such as mite, animal dander, mold spores and cockroach, for which specific environmental control instructions can be given. Smokers must be encouraged to discontinue smoking, and all patients should try to avoid exposure to environmental tobacco smoke and other potential irritants as much as possible. Effective allergen immunotherapy can be continued during pregnancy, but benefit–risk considerations do not generally favor beginning immunotherapy during pregnancy. Asthma medicines are classified into two types: relievers and long-term controllers. Relievers provide quick relief of bronchospasm and include short-acting beta agonists(albuterol is preferred during pregnancy, 2–4 puffs every 4h as needed) and the  anticholinergic bronchodilator ipra- tropium (generally used as second-line therapy for acute asthma – see below). Long-tem control medications are described in Tables 23.1 and 23.2. Chronic asthma Patients with intermittent asthma do not need controller therapy. In patients with persistent asthma, controller therapy should be initiated and progressed in steps (Table23.3) until adequate control is achieved. A classi- fication of asthma control has been published (Table 23.4). Well-controlled asthma means symptoms or rescue therapy requirement less than three times per week, nocturnal symptoms less than three times per month, no activity limitation due to asthma, and, ideally, normal pulmonary function tests. For patients with “not well controlled” asthma (Table 23.4), one step up in therapy (Table 23.3) is recommended. For patients with “very poorly controlled” asthma, a two-step increase, a course of oral corticosteroids, or both should be considered. Before stepping up pharmacological therapy in women whose asthma is not well controlled, adverse environmental exposures, co-morbidities, adherence and inhaler technique should be considered as targets for therapy. Inhaled corticosteroids are the mainstay of controller therapy during pregnancy. Because it has the most published reassuring human gesta- tional safety data, budesonide is considered the inhaled corticosteroid of choice for asthma during pregnancy. It is important to note, though, that no data indicate that the other inhaled corticosteroid preparations are unsafe. Therefore, inhaled corticosteroids other than budesonide may be continued in patients who were well controlled by these agents prior to pregnancy, especially if it is thought that changing formulations may  jeopardize asthma control. A long-acting beta agonist (salmeterol or for- moterol) should be added in patients inadequately controlled on medium dose inhaled corticosteroids (Table 23.1). As described in Table 23.1,
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