Effect of inhaled nitric oxide on experimentally induced pulmonary hypertension in neonatal foals.

The research paper studies the effect of nitric oxide in alleviating pulmonary hypertension, specifically in newborn foals. It finds that the inhaled nitric oxide helps to reduce high pulmonary arterial pressure and improve arterial oxygenation in the foals, hence suggesting its potential as a therapeutic agent in foals suffering from pulmonary hypertension.

Experimental method

• This research was conducted on five 1- to 3-day-old foals to determine the effectiveness of nitric oxide (NO) as a treatment for induced pulmonary hypertension.
• These foals were anesthetized with propofol, intubated, and mechanically ventilated.
• The systemic pressure and pulmonary arterial pressure were recorded every 30 seconds.
• Pulmonary hypertension was artificially induced using a hypoxic gas mixture or a chemical vasoconstrictor (U46619).
• After hypertension was induced, nitric oxide was introduced at a concentration of 80 parts per million (ppm) for 6 minutes under both baseline conditions and during hypertension.
• The effects of various concentrations of nitric oxide (20, 40, 80, and 160 ppm) were then examined during the state of induced hypertension.
• Arterial blood samples were gathered before and after each nitric oxide application for further analysis.

Results

• At about 80 ppm, inhalation of nitric oxide had no effect on the foals’ baseline variables.
• Both the U46619 infusion and the induced hypoxia led to a significant increase in pulmonary arterial pressure and a decrease in arterial oxygenation and hemoglobin saturation.
• During U46619 infusions, the rise in pulmonary arterial pressure was mitigated by nitric oxide, with the degree of mitigation increasing with the dose.
• Meanwhile, the raise in pressure was reversed by nitric oxide during hypoxia.
• Arterial oxygenation and hemoglobin saturation were both significantly improved by all doses of nitric oxide during U44619 infusion, however, this improvement was not seen during hypoxia.
• Nitrogen dioxide and methemoglobin values were safe and non-toxic with all administered nitric oxide concentrations (below 5 ppm and 3% respectively).

Conclusion

• The research found that nitric oxide serves as a potent, selective vasodilator of the pulmonary circulation in newborn foals and could potentially be utilised therapeutically in cases of pulmonary hypertension.