Introduction. Perfluorocarbon (PFC) liquids have been used as a vehicle for gas exchange in liquid and partial liquid ventilation. PFC lowers interfacial surface tension, and thus the pressure needed for lung inflation. PFC ventilation has not been used in conjunction with replacement surfactant. We hypothesized that small quantities of PFC could be an adjunct to surfactant replacement.

Methods. We studied four groups (n=8 each) of preterm rabbit pups(C-section at 27d GA) after tracheostomy and intratracheal instillation of 1) air (control), 2) Survanta (5ml/kg, Surv), 3) Perfluorooctylbromide (5ml/kg, PFC), and 4) a partially emulsified mixture of Surv and PFC (5ml/kg each, Surv+PFC), before air breathing. Pups were ventilated (26/0 cmH2O, rate=30/min.), and dynamic respiratory system compliance (Crs) was measured during one hour after instillation.

Results. Crs values are shown in the table below (mean(SD), in ml/cmH2O/kg). Crs was higher than controls after the instillation of Surv, PFC and PFC+Surv. PFC pups had higher Crs than Surv pups at 10 min of ventilation. The addition of PFC to Surv had an additive effect: Crs for Surv+PFC pups was significantly greater than Surv at 10 and 20 minutes. Crs was not significantly different between the 3 treatments at 30-60 minutes. The reduction in the additive effect of PFC decreased with the clearance of PFC (approx. 60-75% of PFC dose) predicted in ventilated preterm lambs (JAP 83:1033-40, 1997).

Table 1 No caption available.
Full size table

Conclusions. In the preterm rabbit, the addition of PFC to replacement surfactant leads to a more rapid increase in Crs.

Speculation. PFC added to surfactant may increase Crs due to its own surface tension lowering abilities, or may lead to improved distribution of the surfactant, even after it is cleared from the lungs. It may be a useful adjunct to replacement surfactant.