Pulsed inhaled nitric oxide improves arterial oxygenation in colic horses undergoing abdominal surgery.

The researchers conducted a study to assess the impact of pulsed inhaled nitric oxide (INO) on oxygen levels in the blood of horses undergoing abdominal surgery. The study showed that by continuously administering pulsed INO, the oxygen levels in the horses’ blood improved and F-shunt (oxygen shunting within the lungs) was reduced.

Study Design and Process

• The research was a prospective, randomized, clinical trial carried out on thirty horses scheduled for abdominal surgery at the University Animal Hospital in Uppsala, Sweden.
• Anaesthesia was administered to the horses using a standard protocol that included romifidine, butorphanol, diazepam and ketamine and was maintained with oxygen-enriched isoflurane.
• Fifteen horses received pulsed INO during the procedure while the remaining fifteen served as controls, receiving the standard treatment without INO.
• Before any treatment, baseline data was collected. Subsequently, the delivery of pulsed INO commenced.
• Both arterial and venous blood samples were collected and analysed. Additionally, cardiorespiratory parameters were measured, and the oxygen content and F-shunt in the blood were calculated.

Findings

• Horses that were administered pulsed INO showed an increase in arterial oxygen tension (PaO) and arterial oxygen saturation (SaO). Specifically, PaO increased from 10.9±5.7 kPa (82±43 mmHg) to 17.3±6.9 kPa (134±52 mmHg) and SaO from 93±6% to 98±2%.
• Contrarily, in the control group (those not receiving INO), both PaO and SaO saw a decrease. PaO fell from 13.9±9.1 kPa (104±68 mmHg) to 12.1±8.6 kPa (91±65 mmHg), and SaO reduced from 93±7% to 91±8%.
• By the end of the anaesthesia, the oxygen content in the blood of horses given pulsed INO was significantly higher than in the control group.
• Further, the calculated F-shunt – which signifies the proportion of blood that passes through the lungs without being oxygenated – decreased from 39±10% to 27±6% in the INO group but showed no change in the control group.
• Blood lactate concentration, which can indicate lack of oxygen in the body, decreased by 17±21% in the INO group, while no notable difference was observed in the control group.

Conclusions

• The research concluded that pulsed inhaled nitric oxide can effectively reduce F-shunt and enhance arterial oxygenation in horses during abdominal surgery.
• This could potentially mean better surgical outcomes and recovery for the animals. Further research may help understand the full implications of these findings.