Pulmonary microvascular permeability and gas exchange in patients with syndrome X

This clinical study was planned to assess pulmonary microvascular permeability in patients with Syndrome X (SX) by using a functional imaging tool, technetium-99m-diethyltriaminepentaaceticacid ((99m)Tc-DTPA) lung clearance scintigraphy, and the pulmonary functions test, which includes diffusion capacity of the lung for carbon monoxide (DLCO).

The study population consisted of 22 non-smoker subjects divided into two groups. First group comprised 12 patients (4 male, 8 female, mean age: 48±4 years, range 36 to 65) with SX. Ten healthy subject (4 men, 6 female, mean age: 45±3 years, range 34 to 58) were served as control group. Volumetric pulmonary functions, including DLCO were also performed before lung scintigraphy. Alveolar epithelial permeability was assessed by measuring the pulmonary clearance of an inhaled (99m)Tc-DTPA using a gamma camera.

Spirometric data was comparable in both groups. Although volumetric pulmonary measurements were similar, DLCO values of SX patients were lower than those in control (20.9±1.7 ml/min/mmHg vs. 27.8±1.3 ml/min/mmHg, p=0.002). The mean clearance rate of (99m)Tc-DTPA in control subjects was 106±6 min, and this value was lower than patients with SX (179±19 min; p=0.0001).

We conclude that lung is a target organ for SX. The pulmonary gas exchange and microvascular permeability, which is measured by (99m)Tc-DTPA scintigraphy, are restricted without change of volumetric pulmonary functions in patients with SX.