THE (67)GALLIUM-TRANSFERRIN PULMONARY LEAK INDEX IN PNEUMONIA AND ASSOCIATED ADULT-RESPIRATORY-DISTRESS-SYNDROME

1. The aim of the study was to determine the role of increased microva scular protein permeability, as measured by the (67)gallium (Ga)-trans ferrin pulmonary leak index, in pneumonia and associated adult respira tory distress syndrome (ARDS). 2. Eighteen consecutive patients with m icrobiologically confirmed pneumonia (radiographic infiltrates, purule nt sputum) and needing respiratory monitoring (n = 2) or mechanical ve ntilation (n = 16) in the intensive care unit were studied prospective ly. The pulmonary leak index using Ga-67-transferrin and Tc-99m red bl ood cells was measured with a mobile probe system over both lung apice s (normal value below 14.1x10(-3) min(-1)) within 72 h of intensive ca re unit admission, and the lung injury score was calculated from radio graphic, ventilatory and lung mechanical data. 3. Patients with pneumo nia (lung injury score <2.5, n = 10) had a lower (P < 0.01) pulmonary leak index, averaged for both lungs, with a median of 23.9 [range (7.0 -47.0) x 10(-3) min(-1)] than patients with pneumonia-associated ARDS (lung injury score greater than or equal to 2.5, n = 8), and an averag e pulmonary leak index of 37.5 [(23.4-144.2) x 10(-3) min(-1)], so tha t, for all patients, the pulmonary leak index, averaged for both lungs , directly related to the lung injury score (r(s) = 0.61, P<0.01). A n ormal average pulmonary leak index excluded pneumonia-associated ARDS. Patients with unilateral pneumonia had a greater inter-lung differenc e (P<0.01) in the pulmonary leak index between affected and unaffected lung than patients with bilateral pneumonia. The index did not have p rognostic significance. 4. The Ga-67-transferrin pulmonary leak index parallels the degree of radiographic, ventilatory and lung mechanical abnormalities of pneumonia and evolving ARDS. The data support the ide a that the clinical manifestations of pneumonia culminating in ARDS di rectly relate to the degree of microvascular injury. Conversely, the p ulmonary leak index may be used to monitor the effect of anti-inflamma tory drugs in the adjunctive treatment for severe pneumonia aimed at c ircumventing mechanical ventilation in future studies.