Artificial respiration in the anesthetized horse using bilateral, percutaneous, cervical phrenic-nerve stimulation with needle electrodes: a preliminary report.

The researchers performed an initial experiment on four anesthetized horses, using electrical stimulation through needle electrodes to artificially induce respiration – this process was able to effectively simulate natural breathing patterns and volumes for a period of half an hour, suggesting a potential new method for managing respiration in anesthetized equine patients.

Methodology

• The experiment was conducted on four anesthetized horses.
• These horses were made to undergo artificial respiration through the means of percutaneous electrophrenic respiration, a process involving electrical stimulation of the phrenic nerves, which control the diaphragm.
• The electrical stimuli were delivered through long needle electrodes that were inserted bilaterally at the base of the horse’s neck.
• These needles were insulated up to within 1 cm of their tips.
• The frequency of the stimuli given was 35 per second, with each stimulus lasting 0.1 milliseconds.
• Each sequence, or ‘train’, of stimuli lasted for 1 second, representing one instance of ‘inspiration’, or inhalation.

Results

• The study found that the volume of air the horses were able to inhale increased with the intensity of the stimulus.
• Each of the four horses was able to maintain an inhalation volume comparable to that of spontaneous breathing.
• Two of the horses were able to inhale volumes of up to 6 liters, while another was able to inhale 4.5 liters, and the last, 2.5 liters. The lower value in the last horse was believed to be due to less-than-optimal electrode placement.

Implications

• Artificial percutaneous electrophrenic respiration was maintained in every horse for a period of half an hour.
• This suggests that this method could potentially be used as an effective means of managing respiration in anesthetized horses for short periods of time, providing a possible new method of managing respiration in equine anesthesia.