Section
Author
E
Eric BaiLast edited
Sep 11, 2024 4:53 PM
⚠️ Close follow-up
Return to clinic within 2-3 weeks for inhaler monitoring if increasing frequency of nocturnal awakening or ≥ 20% drop in baseline peak expiratory flow
📬 Referral to specialist
Frequent (≥ 2 per year) exacerbations or severe exacerbations requiring hospitalization despite trigger avoidance and using medium or high dose ICS with LABA with good technique ± other adjuncts such as LTRA or OCS. Referral to pulmonology for consideration of biologics.
🚨 Send to the ED
Increased or quiet work of breathing concerning for a suspected asthma exacerbation
Diagnosis
- Diagnosis per GINA requires:
- History of typical variable respiratory symptoms
- Confirmed variable expiratory airway flow limitation
- Documented expiratory airflow limitation
- History of typical variable respiratory symptoms include shortness of breath, wheezing, cough, and chest tightness.
Lab Testing
- CBC w/ diff to evaluate eosinophil levels
- Initial testing for serum IgE should also be considered, especially in patients with difficult-to-control asthma.
- Radioallergosorbent testing should be conducted in the initial work up for asthma as these can potentially identify allergens that may be implicated as triggers for symptom onset.
Pulmonary Function Tests (PFTs)
- PFTs are an important diagnostic tool when evaluating a patient for asthma. Variable expiratory airway flow limitation refers to the reversibility or inducibility of bronchoconstriction. There are several ways to test this, a positive test in one or more of the following satisfies this criteria:
- Positive bronchodilator responsiveness test: The forced expiratory volume over one second (FEV1) is tested before and after administration of a bronchodilator. Positive in adults if >12% increase and 200 mL increase in FEV1 from baseline measurement.
- 2 week peak expiratory flow (PEF) variability: PEF is measured twice daily for 2 weeks. Each day, the higher PEF - lower PEF is the daily variability. Daily variability is averaged over 2 weeks. Positive in adults if > 10% variability.
- 4 week lung function increase in response to treatment: Test FEV1 or PEF before and after 4 weeks of inhaled corticosteroid treatment. In adults, an increase in FEV1 of >12% and >200mL or PEF of >20% is a positive test.
- Exercise challenge test: Test FEV1 and/or PEF before and after 6-8 minutes of exercise on a treadmill or stationary bike at near maximal intensity (Exercise test). For adults, a decrease in FEV1 > 10% and >200 mL from baseline is a positive test.
- Bronchoprovocation testing challenge test: Typically only performed in adults and in a monitored setting, typically with direct supervision of a physician or mid-level provider. Test FEV1 before and after administration of a bronchoconstriction stimulus (methacholine, mannitol, exercise, hyperventilation, among others). A decrease in FEV1 of ≥20% after administration of methacholine, a muscarinic agonist, is a positive test. A decrease in FEV1 of ≥15% after hyperventilation or administration of hypertonic saline or mannitol is a positive test.
- Lung function variability between visits: In adults, variation in FEV1 by >12% and >200 mL outside of respiratory infections is a positive test.
- Documented expiratory airflow limitation criteria is met when FEV1/FVC is < 0.75-0.80. FEV1 is generally a more reliable test than PEF. If PEF is used, the same meter should be used as there is up to 20% variability between meters. The use of z-scores for lung function parameters can be considered in categorizing severity of airflow obstruction in asthma. An FEV1 z-score of >-1.645 is considered normal, between -1.65 and -2.5 is considered mild obstruction, between -2.51 and -4 is considered moderate obstruction, and <-4.1 is considered severe obstruction.
- If a patient has variable respiratory symptoms but does not meet criteria for variable expiratory airway flow limitation, spirometry may be repeated after withholding bronchodilators prior to testing. Fractional excretion of nitric oxide (FENO) testing may be considered in ambiguous cases as a non-invasive marker of type 2 inflammation. The data on FENO in the diagnosis of asthma in adulthood is limited, however there is some benefit to using FENO as a marker of control.
Staging
Management
Medications
GINA guidelines no longer recommend treatment decisions based solely on severity. Instead, focus on response to treatment and escalate ICS intensity (and add on other adjuncts) in a stepwise fashion.
GINA guidelines no longer recommend SABA-only treatment
- GINA recommends all adults with asthma should receive ICS-containing controller treatment, either daily or PRN low dose ICS-formoterol. Note: GINA studies only assessed formoterol, salmeterol has a slower onset.
- Dose of ICS-formoterol:
- Budesonide/formoterol 160/4.5 1-2 puff BID
- Budesonide/formoterol 160/4.5 1 puff PRN
- Max use: 12 puffs per day
- ICS-LABA can be used prior to exercise
- Review inhaler technique or refer to PharmD, a spacer is more effective
- If insurance does not cover ICS-formoterol, can use ICS and albuterol, but should give ICS every time albuterol is taken. Rationale: Patients with mild asthma are still at risk of adverse events (15-20% of asthma deaths are in mild asthmatics)
Monitoring
If suspecting an asthma exacerbation, quiet breath sounds without wheezing is actually a BAD sign. It means they are not moving enough air to wheeze.
- After starting initial treatment, review the patient’s response and asthma control with the help of questionnaires such as the Asthma Control Questionnaire (ACQ) and Asthma Control Test (ACT)
- Given that individuals have day-to-day variability in PEF, an individual's normal range for PEF is defined as 80 and 100 percent of their personal best. Readings below this normal range, if not attributed to reduced effort, may indicate airway narrowing, which can occur prior to the onset of symptoms.
- Each patient's personal best value must be reevaluated annually to account for growth in children and disease progression in both children and adults. PEF reaches a peak at about 18 to 20 years, maintains this level up to about 30 years in males, and about 40 years in females, and then declines with age
