Effects of pulse-delivered inhaled nitric oxide administration on pulmonary perfusion and arterial oxygenation in dorsally recumbent isoflurane-anesthetized horses.

This research investigates the effects of pulse-delivered inhaled nitric oxide on blood flow and oxygen levels in horses under anesthesia. The findings suggest that the introduction of nitric oxide significantly reconfigures blood flow in the lungs, improving oxygen levels and potentially offering a solution for hypoxemia, a common condition in anesthetized horses.

Objective and Methodology

• The aim of this research was to analyze the rearrangement of blood flow in the lungs and its effects on oxygen levels in horses undergoing anesthesia.
• The methodology involved the usage of the multiple inert gas elimination technique (MIGET) and perfusion scintigraphy as imaging techniques to map pulmonary blood flow.
• Furthermore, plasma endothelin-1 concentrations, an indicator of lung function, were measured before, during and after the delivery of pulse-delivered inhaled nitric oxide (PiNO).
• The subjects were three healthy adult Standardbreds, anesthetized and placed in a dorsal recumbency position.
• Nitric oxide was introduced into the inspired gases during the experiment.

Results

• The results demonstrated a significant redistribution of blood flow from the dependent (gravity-affected) region to the nondependent areas of the lungs.
• This redirection of blood flow resulted in improvements in ventilation-perfusion (VA/Q) matching, decreases in pulmonary blood shunting (Qs/Qt), and increases in arterial oxygen content (Pao2).
• However, it was noted that these changes reverted to baseline levels 30 minutes after the cessation of PiNO delivery.

Conclusions

• The introduction of PiNO in anesthetized, dorsally recumbent horses resulted in a redirection of pulmonary blood flow away from dependent, collapsed lung areas (atelectasis) towards nondependent, ventilated lung areas.
• The findings point that hypoxemia, a common issue in anesthetized horses lying on their backs, can be alleviated by introducing nitric oxide to inhaled gases.
• Overall, the addition of nitric oxide during anesthesia could offer a clinical solution for improving oxygenation in horses.