Comparison of ropivacaine with a combination of ropivacaine and fentanyl for the caudal epidural anaesthesia of mares

Antinociceptive effects of low dose lumbosacral epidural ropivacaine in healthy ponies

The objective of this study was to evaluate the safety and efficacy of low dose lumbosacral epidural ropivacaine in ponies. Antinociceptive effects of epidural ropivacaine were evaluated by means of mechanical nociceptive thresholds (MNTs) at several spinal levels in conscious ponies. The effects of ropivacaine on nociceptive afferent transmission to the spinal cord were also assessed by measuring spinal cord somatosensory evoked potentials (SSEPs) in anaesthetised ponies. Ataxia scores were determined in conscious ponies to assess the effects on motor function. A randomised, placebo controlled, double blind cross-over design was used. Low dose lumbosacral epidural ropivacaine led to increases in MNTs at various anatomical locations with a maximum effect at the lumbosacral and sacrococcygeal regions, both with respect to increase in threshold and duration of effect. Analysis of SSEPs showed that epidural ropivacaine influenced both Aβ- and Aδ-mediated afferent transmission to the spinal cord at the level of the lumbosacral junction. Ponies showed mild ataxia after low dose lumbosacral epidural ropivacaine, but all ponies remained standing. Application of low dose lumbosacral epidural ropivacaine provided safe and efficacious antinociceptive effects in conscious and anaesthetised ponies, and could therefore be a valuable addition to multimodal analgesic protocols in Equidae.

Epidural Fentanyl Speeds the Onset of Sensory and Motor Blocks During Epidural Ropivacaine Anesthesia

In this study we examined the onset times of sensory and motor block during epidural ropivacaine anesthesia with and without the addition of fentanyl to the epidural solution. Forty-five young male patients undergoing knee arthroscopic surgery were randomly allocated into 3 groups of 15 patients each: epidural fentanyl (EF; epidural administration of 15 mL of 1% ropivacaine plus 100 mug fentanyl followed by IV injection of 2 mL of normal saline); IV fentanyl (IF; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 100 mug fentanyl); and control (C; epidural administration of 15 mL of 1% ropivacaine plus 2 mL of normal saline followed by IV injection of 2 mL of normal saline). The sensory and motor blocks were assessed by pinprick and modified Bromage scale, respectively. The hemodynamic changes, postepidural shivering, and side effects of epidural fentanyl were also recorded. There was no difference in the distribution of age, weight, and height among the 3 groups. The onset time of sensory block to the T10 dermatome was significantly more rapid in the EF group (13.0 +/- 3.0 min) than in the IF group (16.2 +/- 3.5 min, P < 0.05) or C group (17.7 +/- 3.6 min, P < 0.05). The onset times of motor block up to Bromage scale 1 and 2 were significantly more rapid in the EF group (11.9 +/- 4.6 and 24.4 +/- 5.9 min) than in the IF group (16.9 +/- 4.7 and 30.8 +/- 5.6 min, P < 0.05) or C group (18.3 +/- 4.9 and 32.7 +/- 5.7 min, P < 0.05). There was no difference in the incidence of shivering among the three groups. Pruritus was observed in three patients of the EF group and one patient of the IF group. No nausea, vomiting, respiratory depression, urinary retention, or hypotension was observed in any patient. We conclude that epidural administration of the mixture of 100 mug fentanyl and 1% ropivacaine solution accelerated the onset of sensory and motor blocks during epidural ropivacaine anesthesia without significant fentanyl-related side effects.