Effect of different pulses of nitric oxide on venous admixture in the anaesthetized horse.

This research articulates the effect of varying pulses of inhaled nitric oxide on the condition of atelectasis (collapsed lung areas) often observed in anaesthetized horses. The study indicates that early administration of nitric oxide during inspiration helps reduce the venous admixture in collapsed equine lung areas.

Objective of Research

• The goal of this study was to determine how different timings of nitric oxide (NO) administration during inspiration could affect collapsed lung areas during horse anaesthesia.

Methods Used

• The experiment involved six standard breed trotters who were anaesthetized with isoflurane and placed in a lateral recumbency position.
• Nitric oxide was administered as a pulse. The timing of the pulse varied for the three groups of horses – NOp1, NOp2, and NOp3.
• In group NOp1, the nitric oxide was administered at the beginning of 30% of the inspiration timing.
• In group NOp2, the nitric oxide injection was pulsed into the first 60% of the inspiration timing.
• The third timing group, NOp3, received the nitric oxide between 50 to 80% of the inspiration timing.

Key Results

• The venous admixture decreased by 8(2)% with NOp1 and 10(1)% with NOp2. Both results were significant with P=0.045 and P=0.01 respectively.
• However, the decrease in venous admixture with NOp3 was not deemed significant.

Conclusions

• The results demonstrated that nitric oxide administration in early inspiration positively impacts the reduction of the right to left vascular shunt in collapsed equine lungs. The reduction’s magnitude correlates with the initial size of the shunt.
• Early delivery of NO also prevents its accumulation and the formation of NO2 in rebreathing circuits.
• This research could have implications for human care too, especially for cases where the patient increasingly suffers from atelectasis due to age, overweight, or postoperative intensive care during anaesthesia, and in cases of Acute Respiratory Distress Syndrome (ARDS).