Study objectives: Paraquat, a widely used herbicide,
has been shown to cause severe and often fatal pulmonary fibrosis in
humans and laboratory animals. Although paraquat is known to be
directly cytotoxic to lung parenchyma, changes in routine lung
scintigraphy results after acute paraquat intoxication have not been
reported. The objective of this project was to investigate changes in
lung ventilation (LV) and alveolar permeability (AP) in patients with
paraquat intoxication, using 99mTc diethylenetriamine
pentaacetate (DTPA) radioaerosol lung scintigraphy.
Design: Prospective, blinded study.
Setting: Nuclear medicine and toxicology departments
in two university-affiliated teaching hospitals.
participants: Thirteen patients with acute paraquat intoxication
were included in this study. Ten volunteers without acute paraquat
intoxication were studied for comparison.
results:99mTc DTPA aerosol inhalation and
99mTc macroaggregated albumin (MAA) perfusion lung
scintigraphies were performed to determine LV, AP, and lung perfusion
(LP). Five of the 13 patients (38%) had significant LV
abnormalities; 3 of these 5 patients also showed abnormal LP. Of the 13
patients, 4 patients (31%) showed normal AP and survived. The
remaining 9 patients (69%) showed abnormal AP and died. The mean
values for AP were statistically different (p < 0.01) between
survivor (0.72 ± 0.16%) and nonsurvivor (1.52 ± 0.40%) groups.
Data from the normal volunteers and survival patients showed a
99mTc clearance slope < 1.00%. Data from patients who
died showed a clearance slope > 1.00%.
These results indicate that AP, measured by 99mTc DTPA
aerosol inhalation lung scintigraphy, may help predict outcome in
patients with paraquat intoxication.