CLINICAL INFORMATION

Chest Exam

Chest: Mild basilar rales
CV: WNL
Abdomen: WNL
Extremities: WNL
Neurologic: WNL
Lab work revealed normal complete blood count and chemistries. Serologic study results were negative.

Arterial Blood Gasses (ABGs)

pH: 7.41
PCO₂: 41
PAO₂: 79
Saturation: 95% on room air
Bicarbonate: 26.4
A-a gradient: 17

Teaching Pearl*

There is significant variability in the A-a gradient that limits its utility for prognosticating and following interstitial lung disease (ILD) patients. However, a change in the A-a gradient of 15 mm Hg occurred in a third of the patients who succumbed in the placebo arm of the large interferon gamma study. The relative risk of death for such a change was 2.4. Reference: King et al. Chest; 2005;127:171-177.

*Teaching pearls are mentioned throughout the case to expand on the messages and to guide your practical applications.

Pulmonary Function Tests (PFTs)

FVC: 2.34 liters, 51% of predicted
FEV₁: 1.97 liters, 55% of predicted
FEV₁ to FVC ratio: 84%
Diffusing capacity (DL_co): 13.07 mm Hg/mL/min, 37% of predicted
TLC: 4.42, 60% of predicted