THORACIC AND RESPIRATORYDISORDERS■ Wheezes are usually present, but may be absent in either mild or severe
cases (minimal airflow). Presence of inspiratory wheezing or stridor should
prompt evaluation for upper airway obstruction.
■ Prolonged expiratory phase
■ Findings suggestive of severe airway obstructioninclude:
■ Poor air movement that can manifest itself as absence of wheezing
■ Tachypnea (>30 bpm)
■ Tachycardia (>130 bpm)
■ Pulsus paradoxus (>15 mmHg)
■ Accessory respiratory muscle use
■ Altered mental status
■ Hypoxemia
■ Peak expiratory flow rate (PEF) <100 L/min before treatment or PEF
<300 L/min after aggressive treatment.
DIFFERENTIAL
■ “All that wheezes is not asthma.”Consider CHF, upper airway obstruc-
tion, foreign-body aspiration, vocal cord dysfunction.
■ Other causes include COPD, bronchiectasis, CF.
DIAGNOSIS
■ PEFis most predictive of the severity of exacerbation and should guide
therapy. PEF <100 is considered severe exacerbation.
■ Pulse oximetry is helpful to establish adequate oxygenation, but it is not a
good indicator of ventilation. Capnographyis the noninvasive method of
choice for monitoring ventilation.
■ ABG analysis does not predict clinical outcome and should not supersede
clinical findings in determining need for intubation. However, stages of
asthma have been described based on ABG findings (see Table 10.6).
■ CXRis usually normal or show hyperinflation and is necessary only when a
secondary process is suspected such as pneumonia, CHF, pneumothorax,
or foreign body. Obtain CXR for all first episodes of wheezing.
TREATMENT
Treatment should proceed as follows (see Table 10.7):
■ O 2 therapyto keep the O 2 saturation>90%.
■ Inhaleda 2 -agonist
■ Amount and frequency depends on the degree of airflow obstruction.
■ Drug delivery is equivalent with handheld MDIs and nebulizer ther-
apy in multiple studies; however, the latter is clinically more effective
in patients who are in acute distress.
■ Combination therapy with ipratropium bromide should be used for
the first three treatments in all patients with severe exacerbations.
TABLE 10.6. ABG Findings in AsthmaSEVERITY PHPCO 2 PO 2Mild ↑↓NormalModerate Normal Normal ↓Severe ↓↑↓