Research of the Effects of New Ventilatory Therapy Using the Combination of PLV and NO to Neonates

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Partial liquid ventilation (PVL) with perfluorocarbon (PFC) improves pulmonary gas exchange in the respiratory distress syndrome (RDS). Nitric oxide (NO) is an endothelium-derived relaxing factor in a gaseous form. When inhaled at low concentrations, it may relax constricted pulmonary vascular smooth muscle. We hypothesized the combination of PVL and NO can be more effective to the patients with RDS than when PVL or NO is used alone. Therefore, we conducted animal experiments to investigate this hypothesis. We made RDS animal model using newborn piglets by lung lavage with warm saline.First, the optimal volume of PFC was investigated, Functional residual capacity (FRC) of the animals were 26 ml before lavage and 14 ml after lavage. Lung compliance improved as the volume of PFC was increased from 5 ml/kg to 30 ml/kg in 5 ml increments. However, oxygenation and CO2 elimination worsened at the volume of 25 ml/kg and 30 ml/kg of PFC.These results led us to conclude 15-20 ml/kg, that is very close to FRC, maybe optimal dose of PFC to the patients with RDS.Second, we compared the effects of two different ventilation mode with PLV, which were conventional mechanical ventilation (CMV) and high-frequency oscillatory ventilation (HFOV). During CMV, PLV was able to keep good oxygenation and ventilation. However, once CMV was changed to HFOV, arterial blood gas value worsened. And when animals were changed to CMV again after ventilated by HFOV, blood gas value showed improvement, From these results, we conclude that HFOV is not adequate ventilation mode for PLV.Third, we conducted the another experiment that investigated the mutual effects of the combination of NO and PLV.Oxygenation of piglets remarkably improved during the combination of PLV and NO compared with PLV only. However, we could not performed sufficient number of experiments, therefore, definitive conclusion was not able to be demonstrated here.