Partial liquid ventilation vs gas ventilation: Histologic differences using high frequency and conventional techniques

Partial liquid ventilation (PLV) and high frequency ventilation (HFV) have each been reported to lessen airway/alveolar disruption in animals and humans. No studies have compared HFV to PLV-HFV. We evaluated lung pathology from animals treated using conventional ventilation (CV), HFV, and PLV with either CV or HFV. We hypothesized that PLV produces less lung injury than gas techniques. We studied 61 newborn piglets with saline lavage-induced lung injury (PaO2<60 torr at FiO2 1.0) and 6 unventilated controls. After stabilization on CV (Dräger Babylog), animals were randomized to 1 of 8 groups and ventilated supine for 20 hours: 1] CV (n=8): 2] jet ventilation (JV; Bunnell+IMV 7; n=6); 3) oscillation (HFO;SensorMedics 3100; n=8); 4] flow interruption (HFFI; Infant Star+IMV 7; n-9); 5) PLV-CV (n=7); 6) PLV-JV (Bunnell+IMV 7;n=7); 7] PLV with oscillation (PLV-O; n=7) 8] PLV with flow interruption (PLV-I, Infant Star+IMV 7; n=7). PLV animals received FRC amounts of intratracheal perfluorooctylbromide (LiquiVent™; 30-50 ml/kg); evaporative losses were replaced. Ventilators were adjusted as in clinical use. At 20 hours, animals were killed, lungs removed and inflated to 40 cmH2O, then fixed in formalin. Upper (UL) and lower lobe (LL) slides from animals surviving ≥16 hrs (n=52) were scored for edema, alveolar/interstitial inflammation, hemorrhage, atelectasis, necrosis, and HMD formation on a 0-4 scale by a pathologist (SCS) blinded to ventilation type. Data analysis used Kruskal-Wallis ANOVA and Newman-Keuls post-hoc tests. Mean injury scores are show. lung CV jet ventilation oscillation flow interruption Normal lobes CV PLV-C JV PLV-JV HFO PLV-O HFFI PLV-I upper 6.4 3.7 7.5 4.2 4.6 1.8 10.7 4.3 0.4o lower 10.3 0.7* 5.3 1.8* 4.4 1.4* 7.7 2.0* 0.8o *p<0.05 gas vs PLV °p<0.001 vs all Conclusions: Gas ventilation produced more injury than did PLV techniques, with differences seen predominately in the LLs. Similar UL injury scores suggest unequal PFC distribution, with greater protection In dependent regions. PLV, using either CV or HFV, reduces lung injury after prolonged ventilation. (LiquiVent™ provided by Alliance Pharmaceutical Corp.).