Caudal epidural anesthesia in mares after bicarbonate addition to a lidocaine-epinephrine combination.

The study investigates the effects of adding sodium bicarbonate to a lidocaine-epinephrine solution for caudal epidural blocks in mares. The results indicate that this mixture shortens the onset of anesthesia and duration of ataxia, without impacting the extent or duration of anesthesia.

Research Methodology

• The researchers conducted a prospective randomized controlled trial using six mixed-breed mares, each weighing between 350-440 kg.
• Two caudal epidural injections were given to each mare, 72 hours apart, using different solutions prepared immediately before injection.
• The control solution comprised 7 mL 2% lidocaine hydrochloride with epinephrine hemitartrate and sterile water. The experimental (alkalinized) solution contained the same lidocaine-epinephrine mixture, but added 0.7 mL of 8.4% sodium bicarbonate instead of an equivalent volume of water.
• Nociception (the sensory nervous system’s response to harmful or potentially harmful stimuli) was measured through skin pinching at various sites in the sacral region and around the anogenital area both before and at specified intervals after the epidural injection.
• The researchers also recorded onset and duration times and intensity of ataxia (lack of voluntary coordination of muscle movements).

Research Findings

• Alkalizing the solution led to significant reductions in the average time of onset of loss of nociception in the sacral region and around the anogenital area.
• The study also found that alkalization reduced the average duration of ataxia by one-third without affecting the duration or extent of anesthesia.

Conclusions

• The study concluded that adding sodium bicarbonate to a lidocaine-epinephrine solution is beneficial in speeding up the onset of anesthesia and shortening the duration of ataxia.
• This method does not reduce the length or effectiveness of epidural anesthesia in mares, indicating its potential usefulness in pain control procedures for these animals.