DIAGNOSTIC-VALUE OF THE GA-67 PULMONARY LEAK INDEX IN PULMONARY-EDEMA

We studied the value of a noninvasive, bedside, dual-radionuclide meth od (Ga-67-circulating transferrin and Tc-99m-red blood cells) to measu re pulmonary microvascular permeability in efforts to discriminate bet ween pulmonary edema due to adult respiratory distress syndrome (ARDS) and hydrostatic pulmonary edema (HPE), Methods: Patients had respirat ory insufficiency and bilateral alveolar pulmonary edema on chest radi ographs. All patients, except one, were mechanically ventilated. Patie nts were divided into groups according to various sets of etiologic, h emodynamic and ventilatory factors. Group 1 (n = 8) had risk factors f or HPE only. Group 2 (n = 5) had risk factors for both ARDS and HPE, s uch as a pulmonary capillary wedge pressure (PCWP) above 18 torr. Grou p 3 (n = 13) had risk factors for ARDS only and a PCWP below 18 torr. Patients were also classified on the basis of a lung injury score, usi ng radiographic and ventilatory variables, Group 4 (n = 12) had a scor e below 2.5 and Group 5 (n = 14) above 2.5, arbitrarily defined as ARD S, Any radioactivity measurements over the lungs and in blood within 7 2 hr after admission were used to calculate the 1 hr pulmonary leak in dex as a measure of microvascular permeability (upper limit of normal 14.1 x 10(-3). min(-1)). Results: The PLI (x 10(-3). min(-1)) was medi an 10.2 (range 4.4-16.2) in Group 1,26.8 (14.2-31.9) in Group 2 and 32 .3 (23.0-52.4) in Group 3 (p < 0.001). It was 13.3 (4.4-39.9) in Group 4 and 31.1 (14.2-52.4) in Group 5 (p < 0.01), Using the various defin itions, the sensitivity of a supranormal pulmonary leak index for ARDS was 100% and the specificity varied between 46% and 75%, In receiver operating characteristic curves, the pulmonary leak index performed be st when ARDS and HPE were defined on the basis of risk factors only, a nd performed better than hemodynamic and equally well as ventilatory v ariables in discriminating between edema types, if definitions of the latter were mainly based on hemodynamic and ventilatory variables, res pectively. Conclusion: The Ga-67 pulmonary leak index is a useful tool to differentiate ARDS from HPE.