It is extremely important that an initial physical examination be conducted to rule out other diagnoses and to establish the severity of airway obstruction. The examination shows the patient is alert, but in respiratory distress. The neck shows no lymphadenopathy, thyromegaly, or jugular vein distension. Stridor is not evident. The chest shows increased AP diameter and hyperresonance.
Auscultation reveals bilateral inspiratory and expiratory wheezes with prolonged expiration.
No cyanosis or edema is present. It should be noted that these blood gases might be normal for someone in the early stages of an acute asthma attack. Because of the increased respiratory rate, a decrease in PaCO 2 is often first seen. This may also increase the pH and lower the bicarbonate values. The PaO 2 is lowered due to bronchospasm and increased mucus production.