Pulmonary Clearance of99mTc-DTPA in Infants who Subsequently Develop Bronchopulmonary Dysplasia

Abstract

The lung clearance of inhaled and deposited 99mTc-DTPA is biphasic, with a very rapid initial clearance in premature infants with acute hyaline membrane disease (HMD). Infants who rapidly recover from HMD revert to a monophasic slower clearance rate prior to successful extubation. This raises the possibility that a persistently fast clearance might identify infants who will not recover and in whom brochopulmonary dysplasia (BPD) will subsequently be diagnosed. To examine this possibility, we reviewed our experience using this technique and identified infants who had subsequently developed BPD. These 8 intubated, ventilator-dependent, premature infants inhaled a submicronic aerosol containing 99mTc-DTPA on 14 occasions during the second, third, and fourth weeks of life. Clearance was biphasic, with very rapid initial lung clearance(T1/2 < 2 min) on 5 occasions in 4 infants during their second or third week of life. The other infants had monophasic clearances that were much slower (T1/2 = 52 .+-. 26 SD min). At Day 28 of life, all infants with BPD were ventilator-and/or oxygen-dependent. We conclude that lung clearance of 99mTc-DTPA is very rapid during acute HMD, but that it can normalize before 28 days of life in infants in whom BPD is subsequently diagnosed.