ABSTRACT
The most important objective laboratory value is the level of airflow obstruction as measured by FEY 1 or PEF. Sao2 is valuable to assess level of oxygenation and determine level of 0 2 that should be administered (4). It is impotant to be aware that Sao2 does not measure ventilation; thus, arterial blood gas measurements, particularly the Paco2, are useful for assessing the risk of respiratory failure in those patients presenting with severe obstruction (FEY 1 or PEF S 30% predicted). Capillary gases for assessing Paco2 may be particularly useful in infants. Other laboratory tests are primarily for the monitoring of potential toxicities from therapy. A complete blood count may be appropriate in patients with fever or purulent sputum; however, many patients will have a leukocytosis from a viral infection or secondarily to glucocorticoid administration. Routine chest radiographs have not been shown to be of value unless physical findings of consolidations or pneumothoraces are present (4). Serum electrolytes should be monitored if high-dose continuous inhaled or systemic ~2 agonists are to be used, as they can produce transient decreases in potassium, magnesium, and phosphate (35).
