Study on the nitric oxide inhalation therapy to neonate

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Newborn piglets weighting 1.2 to 1.6 kg on the first or second day of life were obtained. Initial anesthetic induction was performed by inhaled ethyl ether followed by tracheotomy. Then, the pentobarbital sodium and pancronium bromide were intravenously given and assisted ventilation was started. A balloon catheter was advanced into pulmonary artery through the right external jugular vein. A catheter was advanced into descending aorta through the umbilical artery. Pulmonary arterial pressure (PAP) and systemic arterial pressure (SAP) were continuously monitored. Pulmonary hypertension was induced by reducing the inspired oxygen concentration (FiO_2=0.05 to 0.1).(1) Inhaled nitric oxide decreased PAP in piglets model of hypoxic pulmonary hypertension while they did not alter SAP.(2) The decrease rates of PAP were elevated as the concentrations of inhaled NO were increased from 1 to 5 ppm, however its were constant when the NO concentrations were increased from 5 to 40 ppm.The delivered NO concentration is affected by a change in the ventilatory setting during neonatal mechanical ventilatory support. The NO concentration was increased as the settled PIP level was increased. A decrease was seen in the NO concentration as the settled ventilatory flow was increased. The NO concentration fluctuated greatly in association with the settled ventilatory rate.And, we compared the production of nitrogen dioxide (NO2) in ventilatory circuit when high frequency oscillatory ventilation (HFOV) is used as the mode of mechanical ventilation versus intermittent mandatory ventilation. The NO2 concentrations in the combination of the HFOV and the narrow NO administration line were significant high level. This occurs because the back and forth movements of the gas generated by the oscillation had an influence on the NO and oxygen gases in the NO administration line.