Ventilation with hyperoxia promotes cochlear bleeding in rabbits with congenital diaphragmatic hernia.

Abstract

OBJECTIVE: The authors hypothesized that ventilation and hyperoxia may harm the cochlea vasculature in an experimental model of Congenital Diaphragmatic Hernia (CDH) performed in rabbits. METHODS: New Zealand rabbits underwent CDH creation at 25 days of gestation (term = 30 days). CDH was created in fetuses (n = 15) and compared with Controls (n = 15). Six groups were studied: Control, Control Ventilated 21% FiO(Control 21%), Control Ventilated 100% FiO(Control 100%), CDH, CDH Ventilated 21% FiO(CDH 21%) and CDH Ventilated 100% FiO(CDH 100%). Dynamic Compliance (CRS), dynamic Elastance (ERS), and dynamic Resistance (RRS) were measured. The cochleae were then removed, and the apical, middle, and basal slopes of the cochleae were evaluated. Samples were graded using a scoring system for the severity of bleeding: 0 (absent), 1 (mild), 2 (moderate), and 3 (severe). Statistical analysis was performed by contingence and ANOVA. RESULTS: There was no difference in the severity of cochlear bleeding between Controls and CDH without ventilation. Control 21% and 100% had average scores of 2 and 1.2 respectively; CDH 21% and 100% had average scores of 0.4 and 3.8 respectively; RR [CDH 100% / Control 100%] (95% CI) = 3.16 (p < 0.005). CONCLUSIONS: The severity of bleeding was 3.16 times worse with 100% oxygenation in CDH. This information may be helpful for future therapeutic strategies for decreasing SNHL in CDH patients.