Lung Clearance Of Intratracheally Instilled Tc-99m-Tobramycin Using Pulmonary Surfactant As Vehicle

1 The use of pulmonary exogenous surfactant as a vehicle for intratracheally administered antibiotics to improve local antimicrobial therapy has been proposed. The present study investigated lung clearance rates in the rat of intratracheally instilled technetium labelled tobramycin with and without the addition of surfactant to the antibiotic solution.2 The influence of surfactant on Tc-99m-tobramycin lung clearance rates was studied dynamically with a gamma-camera in anaesthetized spontaneously breathing animals and in mechanically ventilated animals.3 The results show that instillation of Tc-99m-tobramycin with use of surfactant as vehicle significantly increases Tc-99m-tobramycin lung clearance compared to instillation of Tc-99m-tobramycin solution alone (P = 0.006 between the two spontaneously breathing groups of animals and P = 0.02 between the two ventilated groups of animals, ANOVA for repeated time measurements). The half life (t1/2) of composite clearance curves in spontaneous breathing animals was 147 min for animals receiving Tc-99m-tobramycin versus 61 min for animals receiving Tc-99m-tobramycin with surfactant. In mechanically ventilated animals this was 163 min versus 51 min, respectively.4 It is concluded that exogenous surfactant, used as vehicle for intratracheally instilled Tc-99m-tobramycin, increases lung clearance rate of Tc-99m-tobramycin in rats.