Clinical implementation of Pulsed inhaled Nitric Oxide in equine anaesthesia
Authors: M. Wiklund
Journal: Acta Universitatis Agriculturae Sueciae
Summary
# Editorial Summary: Pulsed Inhaled Nitric Oxide in Equine Anaesthesia Hypoxaemia remains a stubborn problem during equine general anaesthesia, primarily driven by intrapulmonary shunting and ventilation-perfusion mismatch that is difficult to reverse using conventional recruitment manoeuvres. Rather than attempting to open collapsed lung tissue through high airway pressures, Wiklund's research programme explored an alternative strategy: using pulsed nitric oxide (PiNO) timed to inspiration to selectively vasodilate blood vessels in well-ventilated lung regions, thereby redirecting blood flow away from poorly ventilated areas. Experimental work demonstrated that PiNO effectiveness during mechanical ventilation depended critically on adequate cardiac output and blood pressure, whereas spontaneously breathing horses benefited regardless of haemodynamic status; subsequent clinical trials in both healthy horses undergoing arthroscopy and colic patients showed consistent improvements in arterial oxygenation under both ventilation modes. Most notably, horses receiving PiNO exhibited superior recovery quality compared to controls, with a positive correlation identified between intra-anaesthetic oxygenation levels and post-operative recovery scores. For practitioners, PiNO represents a practical, non-invasive adjunct to improve oxygenation in anaesthetised horses, particularly valuable in cases where conventional recruitment strategies have failed or in high-risk patients; however, further investigation is warranted regarding long-term postoperative outcomes, particularly wound healing trajectories in surgical cases.
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Practical Takeaways
- •PiNO is a simple, clinically effective option to treat hypoxaemia in anaesthetised horses and may improve post-operative recovery outcomes
- •Effectiveness of PiNO during mechanical ventilation depends on maintaining adequate cardiac output and blood pressure; consider spontaneous ventilation if these parameters are compromised
- •Better oxygenation during anaesthesia appears linked to improved recovery quality—prioritising oxygenation management may have benefits beyond the anaesthetic period
Key Findings
- •Pulsed inhaled Nitric Oxide (PiNO) effectively improved arterial oxygenation in both healthy and colic horses during mechanical and spontaneous ventilation
- •PiNO was effective during mechanical ventilation only with adequate cardiac output and blood pressure, but effective under both hypotensive and normotensive conditions during spontaneous breathing
- •Horses receiving PiNO during anaesthesia demonstrated better recovery quality compared to controls, with positive correlation between improved oxygenation and recovery quality