A 68-year-old woman with known IPF presents to your offi ce for follow-up. She states that her lung breathing trouble seems to be about the same, but she has felt a little weaker lately. Today on examination, her O2 saturation is 93% on 2 L O2 by nasal cannula. Her lung examination again reveals coarse, Velcro-like inspiratory crackles at both bases. She does not have elevated jugular venous pressure or peripheral edema, but you do note clubbing. Her pulmonologist has recently been treating her lung disease with prednisone and azathioprine, but the patient is not sure if this is helping. You order an arterial blood gas, chest x-ray, pulmonary function testing, and a 6-minute walk test.
Which of the following findings would be most predictive of further clinical deterioration of the patients disease?
A. Decrease in forced vital capacity (FVC) by 12% from her previous study B. Moderate increase in reticular opacities on chest x-ray C. Carbon dioxide tension (PCO2) > 45 mm Hg on arterial blood gas D. Decrease in distance walked in 6 minutes by 10 meters
Decrease in forced vital capacity (fvc) by 12% from her previous study-ostensibly, similar patients may behave quite differently over time, and our ability to distinguish this on initial assessment is relatively poor. several authors have investigated the predictive power of trends in clinical progression to predict mortality. a number of studies have now pointed to a change in fvc, often set at 10%, as being clinically predictive of further disease progression. other measures of disease progression, such as measures of oxygenation (a-a gradient, dlco, amount of desaturation on a 6-minute walk test) and a decrease in 6-minute walk distance, may have prognostic signifi cance. of all of these, a change in fvc of 10% may be the most reliable end point.