Aerosol Characteristics of 99 mTc . pentetic Acid ( DTPA ) and Synthetic Surfactant

This study evaluated the feasibility of using Te-pentetic acid (DTPA) as a radioactive tracer for aerosolized synthetic surfactant (DPFC, cetyl alcohol, tyloxapol). The “Tc-DTPA was admixed with surfactant and aerosolized using a nebulizer system interfaced to a ventilator with a cascade impactor attached to the endotracheal tube. Particle size distribution for DPPC, cetyl alcohol, and ‘Tc-DTPA were almost identical during the 0to 15-, 15to 30-, and 0to 30-mm collection periods. Tyloxapol exhibited a unique distribution pattern with increased deposition in large (>10 m) and small (0.65 to 1.1 im) particles. The mass median aerodynamic diameter for all aerosolized components was in the respirable range of 2.1 to 2.5 sm. A mixture of “Tc-DTPA with synthetic surfactant appears to be a reasonable method to evaluate surfactant deposition. (Chest 1994; 105:1 765-69)