Study objective: To investigate the finding of increased alveolar-arterial (A-a) gradient in adult patients with measles who have normal results on both pulmonary auscultation and chest radiography.
Design: Retrospective, descriptive case series.
Setting: An urban county teaching hospital in southern California.
Participants: Consecutive adult patients with the clinical diagnosis of measles seen in the emergency department.
Methods: Patients were considered to have pneumonitis if they had any of the following: ED diagnosis of pneumonia; an A-a gradient of more than 30 mm Hg; one or more infiltrates on chest radiograph.
Results: Seventy-five patients, including 44 men and 31 women (median age, 25 years; 25% to 75% interquartile range [IQR], 20 to 28 years) were seen during the 36-month study period. Forty-three patients (57%; 95% confidence interval [CI], 45% to 69%) had pneumonitis, with a median A-a gradient of 42 mm Hg (IQR, 34 to 48 mm Hg). Twenty-seven of the 43 patients with pneumonitis (63%; CI, 48% to 77%) had both normal pulmonary auscultation findings and normal chest radiographs; this represented 36% of the study population (CI, 25% to 50%). Thirty-eight of the 43 patients with pneumonitis were admitted; one patient was later intubated after respiratory failure developed. Two of the 5 patients with pneumonitis who were sent home were admitted the following day for worsening symptoms. All 75 patients eventually did well.
Conclusion: A significant percentage of adult patients with measles presenting to an ED with both normal pulmonary auscultation and normal chest radiographs have increased A-a gradients. These patients warrant close follow-up and perhaps hospital admission.