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Astma bij volwassenen: diagnose en monitoring in de eerste lijnPublished by: Werkgroep Ontwikkeling Richtlijnen Eerste Lijn (Worel)Last published: 2020Asthme chez l’adulte : diagnostic et surveillance en soins de santé primairesPublished by: Groupe de Travail Développement de recommmandations de première ligneLast published: 2020Clinicians should record the evidence underlying the diagnosis of asthma, as well as the patient's level of symptoms, modifiable risk factors, and lung function. Objective testing is required for diagnosis.[52][53] Comorbidities should be identified and addressed, where possible. In an urgent care setting or where a patient presents with an acute exacerbation, please refer to guidance for diagnosing Acute asthma exacerbation in adults.
History
Recurrent episodes of dyspnea, chest tightness, wheezing, or coughing typically occur.
The patient's medical history may help to identify allergen exposures that worsen the asthma: for example, episodes may be exacerbated by exposure to irritants such as tobacco smoke or fumes from chemicals, such as bleach. Attacks may occur seasonally or upon exposure to cats in allergic patients. Exercise can also make the symptoms worse.
People with more severe asthma have night-time symptoms, waking them up from sleep.
In severe exacerbations, patients are continuously short of breath and may use accessory muscles of respiration.
In athletes, there should be a low threshold for ruling out exercise-induced laryngeal obstruction (EILO) and breathing pattern disorder (BPD). Symptoms associated with EILO typically include noisy breathing and upper chest/throat discomfort or restriction, and are amplified during intense exercise. BPD is a common cause of unexplained dyspnea and should be considered in athletes with variable symptoms and normal investigations. BPD may be comorbid with EILO and exercise-induced bronchoconstriction.[54]
Physical exam
The exam may be normal in patients with bronchial asthma. Examination of the nasal passages may reveal nasal polyposis or nasal congestion. Chest auscultation may reveal expiratory wheezes.
With more severe asthma, the wheezes may be audible without the use of a stethoscope. In patients with severe exacerbations, the lung examination may be silent.
Auscultation sounds: Polyphonic wheeze
Auscultation sounds: Expiratory wheeze
Tests
Characteristic symptoms together with confirmed variable expiratory airflow limitation are required to make a diagnosis of asthma. The Global Initiative for Asthma (GINA) defines confirmed variable expiratory airflow limitation as documented excessive variability in lung function plus documented expiratory airflow limitation.[52]
For patients presenting for the first time or with an acute exacerbation, chest x-ray, complete blood count, and differential are indicated to exclude other pathologies. See Acute asthma exacerbation in adults.
For information on aerosol transmission of coronavirus disease 2019 (COVID-19) in healthcare settings, see Coronavirus disease 2019 (COVID-19) (Etiology).
Pulmonary function testing (PFT)
PFTs including forced expiratory volume at 1 second (FEV₁) and forced vital capacity (FVC), are used to demonstrate airflow limitation. Adults without airflow limitation normally have an FEV₁/FVC ratio of >0.75 to 0.80.[52][55]
The diagnosis of asthma is confirmed by one or more tests confirming excessive variability in lung function. A bronchodilator reversibility test may be used, which can demonstrate reversibility of airflow obstruction to short-acting bronchodilator, usually defined as improvement in FEV₁ by >12% and >200 mL from baseline.[52] However, it should be noted that a normal PFT result is possible during periods of quiescence. Refer to the Diagnostic criteria for further information.
A guide on how to perform and interpret spirometry, including common pitfalls.
Peak expiratory flow (PEF)
PEF monitoring demonstrating diurnal variability (defined as [highest daily PEF - lowest daily PEF]/[highest daily PEF]) can help diagnose asthma, especially occupational (work-related) asthma.[55] The diagnosis of asthma is supported if there is excessive variability in twice-daily PEF over 2 weeks. In adults, an average daily diurnal variability in PEF of >10% is considered excessive.[52] An increase in PEF by >20% from baseline after 4 weeks of treatment also indicates excessive variability. PEF is also useful as an alternative to spirometry in an acute setting and can be readily performed as an outpatient or in the home to monitor disease progress for monitoring progress. However, PEF does not always reflect the level of obstruction of the lung as accurately as the FEV₁ and FEV₁/FVC ratio, and accuracy depends on the patient's effort.
How to use a peak flow meter to obtain a peak expiratory flow measurement.
Exercise-induced bronchoconstriction
Describes acute airway narrowing that occurs as a result of exercise. Exercise-induced symptoms may occur in up to 90% of people with asthma.[2] Exercise-induced bronchoconstriction is diagnosed on the basis of changes in lung function after exercise, and not on the basis of symptoms. Guidelines from the American Thoracic Society (ATS) recommend using the difference between the pre-exercise FEV₁ and the lowest FEV₁ value recorded within 30 minutes after exercise, and expressing this as a percentage of the pre-exercise value. Exercise-induced bronchoconstriction is diagnosed if the percentage fall in FEV₁ after exercise is ≥10%.[59] Objective assessment of exercise-induction bronchoconstriction is particularly important in athletes as respiratory symptoms are poorly predictive of airway disease in this patient group.[54]
Allergy testing
Indicated in patients with a possible allergic component to their disease, including skin-prick testing and immunoassay for allergen-specific immunoglobulin E (replacing the radioallergosorbent test [RAST]). These tests can reliably determine sensitivity to inhalant allergens to which the patient is exposed. Allergy testing is recommended for patients with persistent asthma requiring regular preventer therapy. It may also be considered in patients with asthma and allergic rhinitis to clarify whether allergens are contributing to disease. If allergy is not present there is no need to consider anti-allergy measures.
Challenge tests
May be considered to support the diagnosis if spirometry and PEF do not show reversibility and variability. They are divided into: direct (using agents that directly constrict airway smooth muscle (i.e., histamine or methacholine) and indirect (methods or agents that activate mast cells to release mediators such as histamine and leukotrienes to constrict airway smooth muscle: e.g., exercise, eucapnic hyperventilation, inhaled hypertonic saline, mannitol, or adenosine monophosphate) challenges. These direct and indirect challenges reflect the baseline fixed (airway remodeling) and episodic variable (inflammatory) components of airway hyper-responsiveness, respectively.[60] Challenge tests are more resource-intensive than those such as the bronchodilator reversibility test.[55]
Fractional exhaled nitric oxide (FeNO)
FeNO is a measure of airway-specific eosinophilic inflammation that can be used in addition to standard tests as an adjunctive tool for the diagnosis of asthma and/or to determine asthma control.[61] The 2020 US National Asthma Education and Prevention Program Coordinating Committee (NAEPPCC) guidelines recommend FeNO measurement as an adjunct to the diagnostic process, if the diagnosis of asthma is uncertain after obtaining a detailed history and performing other diagnostic workup.[62] In addition, the NAEPPCC guidelines state that FeNO may be used as part of an ongoing monitoring and management strategy for people with persistent asthma, if the strategy includes frequent assessments and if the FeNO level is not used in isolation to determine asthma control.[62] FeNO, when used in combination with sputum eosinophilia, has a high sensitivity and specificity; however, sputum eosinophil count is not a standard diagnostic test in the US or Europe at present.[55][63][64][65]
GINA does not recommend FeNO as a test for confirming or excluding a diagnosis of asthma, citing the overlap between FeNO levels among people with and without asthma.[52] GINA asserts that the main role of FeNO is to help guide treatment decisions in patients with severe asthma. Although FeNO is modestly associated with some markers (sputum and blood eosinophil levels), levels vary depending on a range of patient factors. Elevated FeNO levels can be seen in patients with airway eosinophilia due to other underlying conditions with type 2 inflammation such as chronic rhinosinusitis or allergic rhinitis. FeNO levels may also be normal in nonallergic asthma phenotypes (e.g., neutrophilic asthma); lower in smokers, during periods of active bronchoconstriction, and the early phases of an allergic response; and can be either increased or decreased during viral respiratory infections.[52]
Two Cochrane systematic reviews evaluating at tailored asthma therapy to either sputum eosinophils or FeNO levels reported fewer exacerbations in each group, but no significant difference in all other outcomes, including quality of life, FeNO levels, or inhaled corticosteroid dose.[66][67] The American Thoracic Society (ATS) recommends measurement of FeNO in all patients with asthma in whom treatment is being considered (conditional recommendation, low confidence in estimates of effect).[68] FeNO values that determine decision-making thresholds are yet to be determined due to lack of evidence.[68] FeNO values should be considered alongside other factors, such as exacerbation risk, to guide individual treatment decisions.[68] The universal use of sputum eosinophils to guide asthma therapy remains unsupported based on current evidence.
Imaging studies
Chest imaging (x-ray or high-resolution CT [HRCT]) may demonstrate hyperinflation in asthma. HRCT can diagnose bronchiectasis and can distinguish cardiac from pulmonary diseases. However, imaging is not routinely recommended for the diagnosis or management of asthma.
CT sinus can show evidence of chronic rhinosinusitis and nasal polyps, which are associated with more severe asthma. The presence of chronic rhinosinusitis with nasal polyposis can also help identify candidates for biologic therapy.
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