High frequency oscillatory ventilation, exogenous surfactant, and partial liquid ventilation: Differential treatment effects on gas exchange, hemodynamics and pathology

Exogenous surfactant (S), partial liquid ventilation (PLV) using FRC amounts of perfluorocarbon (PFC) and high frequency ventilation (HFV) have each been reported to lessen airway/alveolar disruption in animals and humans. Also, low PFC volumes may be effective during HFV. We evaluated physiologic responses and lung pathology in 32 newborn piglets with saline lavage-induced lung injury (PaO2<60 torr at FiO2 1.0) treated using conventional ventilation (CV; Dräger Babylog)+S+PLV (n=8); HFV (SensorMedics 3100)+S (n=8); HFV+S+10 mL/kg PFC (HFV+lo PLV; n=8) and HFV+PFC to FRC (PLV+hi PLV; n=8). We hypothesized that HFV+S+PLV produces less lung injury than CV+S+PLV or HFV+S. We also tested a secondary hypothesis, that HFV+S+lo PLV is similar to other PLV types. After stabilization on CV, animals were randomized and ventilated for 20 hours. PLV animals received intratracheal perflubron (LiquiVent™); evaporative losses were replaced hourly. Ventilators were adjusted as in clinical use. Physiologic variables (heart rate, blood gases, blood pressure, airway pressure) were measured at baseline; after lung injury, S and PFC treatments; and hourly. At 20 hours, animals were killed, lungs removed and inflated to 30 cmH₂O, then fixed in formalin. Upper and lower lobe slides were scored for HMD formation, edema, alveolar/interstitial inflammation, alveolar/interstitial hemorrhage, atelectasis, and necrosis on a 0-4 scale. Data analysis used Kruskal-Wallis ANOVA and Newman-Keuls post-hoc tests. Mean total injury scores are shown. Lung lobes CV+S+PLV HFV+S HFV+S+lo PLV HFV+S+hi PLV upper 7.3 14 6.4 5.8 lower 5.8 15.3 * 5.1 4.6 * p<0.01 HFV+S vs all Conclusions: All techniques provided similar physiologic stability. HFV required higher Paw (p<0.05 vs CV). Contrary to our primary hypothesis, lung injury was similar in all PLV groups, and less than during HFV+S, HFV+S+lo PLV was not different from other PLV groups. These data show no additional lung protection from HFV+S+PLV as compared to CV+S+PLV. (LiquiVent™ provided by Alliance Pharmaceutical Corp.).