The Effects of Clonidine Added to Mepivacaine for Paronychia Surgery Under Axillary Brachial Plexus Block

Abstract

We hypothesized that onset of sensory block is delayed in infected versus healthy tissues within the same nerve distribution after axillary brachial plexus block (ABPB) and that clonidine added to mepivacaine would enhance anesthesia and postoperative analgesia. Forty-one outpatients undergoing thumb/index paronychia surgery under ABPB were randomly assigned to receive in a double-blind fashion 400 mg mepivacaine plus either 100 microg clonidine (clonidine group, n = 21) or 2 mL saline (placebo group, n = 20). Onset of sensory block in the infected area was delayed compared with healthy areas of the same nerve distribution (24.7 +/- 5.5 min versus 21.3 +/- 7.2; P = 0.02 for median and 21.6 +/- 7.8 min; P = 0.04 for radial) within the placebo group. In the clonidine group, when compared to placebo i) onset of sensory block in both the median and radial nerve territories was accelerated (11.1 +/- 5.6 and 10.5 +/- 5.2 versus 21.3 +/- 7.2 and 21.6 +/- 7.8 min, respectively; P < 0.001), ii) onset of sensory block in the region of infection was accelerated (9.1 +/- 1.9 versus 24.7 +/- 5.5 min; P < 0.001), iii) duration of anesthesia (275 +/- 75 versus 163 +/- 57; P = 0.04) and time to first analgesic requirement (279 +/- 87 versus 197 +/- 84 min; P = 0.002) were prolonged with decreased visual analog scale scores at this time (30 +/- 18 versus 70 +/- 24; P < 0.001), and iv) verbal numeric rating scores were decreased at 24 h (1.7 +/- 2.2 versus 4.1 +/- 3.0; P = 0.002) and 48 h (0.1 +/- 0.5 versus 1.5 +/- 2.4; P = 0.01) postoperatively. Our findings suggest that in the setting of distal infected tissue surgery under ABPB infected tissues are resistant to anesthesia compared with healthy areas within the same nerve distribution and clonidine added to mepivacaine enhances both anesthesia and postoperative analgesia.

The effects of bupivacaine combined with different adjuvants on block onset and duration and on ion channel expressions (SCN9A, TRPM) in sciatic nerve block in rats

“…Kanazi et al (25) examined the effects of bupivacaine added to a low dose of dexmedetomidine or clonidine in spinal anesthesia and showed that both adjuvants decrease block onset time and increase the motor and sensory block times, which is in accordance with our study. Even though it has been shown in many studies that clonidine increases the anesthesia and analgesia times in peripheral nerve blocks, it has been reported that this effect is less distinct when combined with long-acting anesthetics (26)(27)(28). Another study has suggested a more effective blockade by clonidine in C-fibers, which was more effective than that in Aα-fibers in rat sciatic nerve models (29).…”

A double blind randomized study to assess the addition of clonidine to ropivacaine in supraclavicular brachial plexus block

“…These results are in consistent with the earlier studies. 4,10,11 The time between the supraclavicular block administration and onset of pain (i.e. VAS >4) requiring the administration of a rescue analgesic, was measured as the duration of analgesia.The time for first rescue analgesia was increased in clonidine-ropivacaine group.…”

Clonidine as an Adjuvant to 0.5% Ropivacaine for Supraclavicular Brachial Plexus Block in Patients Undergoing Orthopedic Surgery of Forearm and Hand - A Randomized Controlled Trial

“…Patient was requested to compare the pinprick (26 G needle) sensation on the test arm to that in the contra lateral arm as reference on a scale range of 0 = no sensation to 100 = full sensation. Sensory block onset was defined as reduction in sensibility to 30% or less 13 . If, at the end of 30 minutes after injection, any of the major nerves involved in the area of planned surgical intervention had a sensibility of more than 30%, they were separately blocked or alternative method of anesthesia was chosen and the patient was excluded from further investigation under this study.…”

“…If, at the end of 30 minutes after injection, any of the major nerves involved in the area of planned surgical intervention had a sensibility of more than 30%, they were separately blocked or alternative method of anesthesia was chosen and the patient was excluded from further investigation under this study. Duration of sensory block was defined as the time interval between injection and complete recovery of sensation 13 . The patients were asked to note the complete recovery of sensation, which was then verified by the anesthetist.…”

“…Motor block (MB) was determined using the modified British Medical Research Council rating scale ranging from 5 (normal power) to 0 (complete paralysis). Motor block onset is defined as a reduction in power to 3 or less 13 . Student's t test was used to compare mean values between two groups.…”