Effects of treatment with PiNO (Pulsed Inhaled Nitric-Oxide) on the metabolism in colic horses undergoing abdominal surgery.

Abstract: The main objective of this research was to study how increased arterial oxygenation by the use of Pulsed Inhaled Nitric-Oxide (PiNO) influenced the metabolic and cardiovascular parameters on horses undergoing acute abdominal surgery because of colic. The parameters blood lactate, blood glucose, pH and heart rate were evaluated before and during anesthesia and closely after recovery. The study showed that blood lactate concentrations decreased significantly during anaesthesia in horses treated with PiNO compared to non-treated horses. It was also seen that the lactate concentration decreased most in horses with the highest levels before PiNO treatment. Since enhanced oxygen extraction ratio was evident in the PiNO group, improved oxygen delivery to the tissue may be a possible explanation for the improved situation. PiNO did not influence levels of blood glucose, pH or heart rate. It became evident that the majority of horses included in the study were subject to a respiratory acidosis caused by hypoventilation during spontaneous breathing. It also became evident that all horses were hyperglycemic, probably because of a stress-response which may have increased the level of cortisol and resulted in temporary reduced insulin sensitivity. Mechanical ventilation and insulin treatment is suggested for future research to correct the hypercapnia and improve the metabolic situation. Future research is further encouraged to study the effect of PiNO treatment during recovery in the postoperative period and to see if the treatment can influence the long term clinical outcome.