Abstract

Pulmonary artery aneurysms (PAA) are typical of pulmonary involvement (PI) in Behcet’s Disease (BD). PAA carries a high mortality despite treatment and invasive diagnostic methods may be hazardous. BD patients with PAA have altered pulmonary blood flow, therefore we hypothesized that noninvasive measurement of pulmonary capillary blood flow (Q) may be predictive of PI in BD. In 31 BD patients, Q was measured by single exhalation technique using a rapid infrared analyzer system which assesses the uptake of acetylene into pulmonary circulation. Predicted Q values (% Q pred) were calculated based on gender, age and weight as described by Huang in 1994. Obstructive airway disease was excluded by spirometry in all subjects. Normal cardiac ejection fractions with no intracardiac shunts was confirmed in all patients by echocardiography. All patients underwent contrast enhanced spiral computed tomography (CT) and high resolution CT (HRCT) scans of thorax. Patients with PAA on CT also had lung perfusion scans. Mean Q pred was compared between patients with and without PAA. Eleven of thirty one patients had PAA which did not cause airway obstruction as seen on expiratory HRCT. Q pred was lower in patients with PAA (83.5±8.2) than in those without PAA (95.4±11.1) (p=0.001). Our data represents the first use of noninvasive Q measurements in BD patients. Although further research is required at exercise, this safe and practical technique may be a noninvasive diagnostic tool for prediction of PI at an “earlier stage” in BD.