Clonidine as an adjuvant for lidocaine in axillary brachial plexus block in patients with chronic renal failure

The effect of adjuvants added to local anaesthetics for single-injection upper extremity peripheral regional anaesthesia: A systematic review with network meta-analysis of randomised trials

BACKGROUND

Peripheral regional anaesthesia is frequently used for upper extremity surgery. To prolong the duration of analgesia, adjuvants can be added to single-injection local anaesthetics. Despite attempts to compare several adjuvants in pairwise meta-analyses, a comprehensive comparison is still missing.

OBJECTIVE

The objective of this network meta-analysis was to determine the effectiveness of adjuvants in upper extremity peripheral nerve blocks.

DESIGN

A systematic review of randomised controlled trials with network meta-analyses.

DATA SOURCES

A literature search in Embase, CENTRAL, MEDLINE and Web of Science was performed up to March 2023.

ELIGIBILITY CRITERIA

Randomised trials comparing different adjuvants injected perineurally in peripheral upper extremity nerve blocks were eligible. Frequentist network meta-analysis was conducted using a random effects model with physiological saline as the comparator. The primary endpoint was the ratio of means (ROM) of the duration of analgesia.

RESULTS

The review included 242 randomised controlled trials with a total of 17 391 patients. Twenty-eight adjuvants were compared in the largest networks. Most network estimations consisted of a high proportion of direct evidence. Fourteen adjuvants increased the duration of analgesia significantly by the following factors, ROM [95% confidence interval (CI)]: dexamethasone 1.95 (1.79 to 2.13), buprenorphine 1.83 (1.51 to 2.24), butorphanol 1.84 (1.41 to 2.39), potassium chloride 1.89 (1.15 to 3.11), dexmedetomidine 1.70 (1.59 to 1.81), sufentanil 1.70 (1.27 to 2.29), ketorolac 1.68 (1.24 to 2.27), midazolam 1.55 (1.24 to 1.94), tramadol 1.52 (1.32 to 1.75), nalbuphine 1.50 (1.30 to 1.72), morphine 1.43 (1.09 to 1.88), magnesium sulfate 1.42 (1.20 to 1.67), clonidine 1.36 (1.24 to 1.50) and fentanyl 1.23 (1.08 to 1.40). Inconsistency in network meta-analysis was substantial. Overall side effect rates were low with all adjuvants.

CONCLUSION

The best interventions to prolong the duration of analgesia were dexamethasone, followed by dexmedetomidine, opioids, electrolytes, ketorolac and midazolam. There are general concerns about the quality of underlying studies and the risk of publication bias.

TRIAL REGISTRATION

PROSPERO 2018 CRD42018115722.

Effect of intravenous dexamethasone on the duration of postoperative analgesia for popliteal sciatic nerve block: a randomized, double-blind, placebo-controlled study

Background

Intravenous (IV) dexamethasone prolongs the duration of a peripheral nerve block; however, there is little available information about its optimal effective dose. This study aimed to evaluate the effects of three different doses of IV dexamethasone on the duration of postoperative analgesia to determine the optimal effective dose for a sciatic nerve block.

Methods

Patients scheduled for foot and ankle surgery were randomly assigned to receive normal saline or IV dexamethasone (2.5 mg, 5 mg, or 10 mg). An ultrasound-guided popliteal sciatic nerve block was performed using 0.75% ropivacaine (20 ml) before general anesthesia. The duration of postoperative analgesia was the primary outcome, and pain scores, use of rescue analgesia, onset time, adverse effects, and patient satisfaction were assessed as secondary outcomes.

Results

Compared with the control group, the postoperative analgesic duration of the sciatic nerve block was prolonged in groups receiving IV dexamethasone 10 mg (P < 0.001), but not in the groups receiving IV dexamethasone 2.5 mg or 5 mg. The use of rescue analgesics was significantly different among the four groups 24 h postoperatively (P = 0.001) and similar thereafter. However, pain scores were not significantly different among the four groups 24 h postoperatively. There were no statistically significant differences in the other secondary outcomes among the four groups.

Conclusions

This study demonstrated that compared to the controls, only IV dexamethasone 10 mg increased the duration of postoperative analgesia following a sciatic nerve block for foot and ankle surgery without the occurrence of adverse events.

[Comparison of adductor canal block for analgesia in arthroscopic surgery with ropivacaine alone and ropivacaine and clonidine]

BACKGROUND AND OBJECTIVES

Inadequate pain relief after anterior cruciate ligament reconstruction affects mobility leading to development of adhesions, weakened ligament insertion and muscle atrophy. Adductor canal block for postoperative analgesia preserves quadriceps strength. The present study was conducted to compare pain free period in patients undergoing arthroscopic anterior cruciate ligament reconstruction, receiving ultrasound-guided adductor canal block with ropivacaine alone and ropivacaine with clonidine.

METHODS

A prospective randomized double blinded study was conducted including sixty-three adult, ASA class I, II patients undergoing anterior cruciate ligament reconstruction. They were randomized into three groups: Group S - control group received adductor canal block with 30mL saline, Group R - ropivacaine group received adductor canal block with 30mL of 0.375% ropivacaine and Group RC - clonidine group received adductor canal block with 30mL of 0.375% ropivacaine with clonidine 1μg.kg^-1. The primary aim was to compare the pain free period in patients receiving adductor canal block with ropivacaine alone or ropivacine with clonidine. The secondary outcomes were pain score at rest and movement, total analgesic requirement, sedation score and postoperative nausea and vomiting.

RESULTS

The mean pain free periods were 20min, 384.76min and 558.09min for Group S, Group R and Group RC, respectively and this difference was statistically significant (p < 0.001). There was no significant difference between Group R and Group RC in terms of pain scores at rest and movement and total analgesic requirement.

CONCLUSION

Addition of clonidine to ropivacaine in USG guided adductor canal block led to significant prolongation of pain free period though pain score at rest and movement, and rescue analgesic requirement, did not differ.

Adding low concentrations of clonidine to ropivacaine for transversus abdominis plane blocks does not reduce plasma ropivacaine levels, suggesting a lack of vasoconstrictor effect

Clonidine has been used successfully to prolong the duration of action of local anaesthetics in peripheral nerve blocks, but its mechanism of action in this setting remains unclear. Some studies suggest that clonidine exerts a vasoconstrictor effect, limiting the washout of local anaesthetic from its site of deposition. We investigated this potential vasoconstrictor effect, using plasma ropivacaine concentrations as a surrogate measure of vasoconstriction, in patients who received transversus abdominis plane (TAP) blocks with and without clonidine. Eighty women undergoing laparoscopic gynaecological surgery were randomly assigned to receive one of four TAP block solutions: 0.2% ropivacaine (control), ropivacaine with clonidine 2 μg/kg (clonidine), ropivacaine with 1:400,000 adrenaline (adrenaline) or ropivacaine and a subcutaneous injection of clonidine 2 μg/kg (SC clonidine). The primary outcome was total venous plasma ropivacaine concentrations up to 6 h after the block. There were no significant differences in plasma ropivacaine concentrations between the control group and the clonidine group at any timepoint in the study, nor were there differences in either the mean maximum ropivacaine concentration ( C_max) (1.99 μg/mL versus 2.05 μg/mL, P = 0.712) or the time to maximum concentration ( T_max) (51.0 min versus 56.0 min, P = 0.537). The SC clonidine group also did not differ significantly from the controls ( C_max 2.13 μg/mL versus 1.99 μg/mL, P = 0.424; T_max 43.5 min versus 51.0 min, P = 0.201). Plasma ropivacaine concentrations in the adrenaline group were significantly lower than the controls from 10 to 90 min ( P < 0.003 for each comparison), and the C_max was less than that of the control group (1.36 μg/mL versus 1.99 μg/mL, P < 0.001) with a longer T_max (103.5 min versus 51.0 min, P = 0.001). These findings indicate that clonidine at a concentration of 1.35 μg/mL added to ropivacaine for TAP blocks did not produce a reduction in plasma ropivacaine concentrations. This suggests a lack of vasoconstrictor effect during TAP blocks. Further studies should evaluate whether vasoconstriction occurs when clonidine is used at higher concentrations or for other blocks.

[Comparison of adductor canal block for analgesia in arthroscopic surgery with ropivacaine alone and ropivacaine and clonidine]

BACKGROUND AND OBJECTIVES

Inadequate pain relief after anterior cruciate ligament reconstruction affects mobility leading to development of adhesions, weakened ligament insertion and muscle atrophy. Adductor canal block for postoperative analgesia preserves quadriceps strength. The present study was conducted to compare pain free period in patients undergoing arthroscopic anterior cruciate ligament reconstruction, receiving ultrasound-guided adductor canal block with ropivacaine alone and ropivacaine with clonidine.

METHODS

A prospective randomized double blinded study was conducted including sixty-three adult, ASA class I, II patients undergoing anterior cruciate ligament reconstruction. They were randomized into three groups: Group S - control group received adductor canal block with 30mL saline, Group R - ropivacaine group received adductor canal block with 30mL of 0.375% ropivacaine and Group RC - clonidine group received adductor canal block with 30mL of 0.375% ropivacaine with clonidine 1μg.kg^-1. The primary aim was to compare the pain free period in patients receiving adductor canal block with ropivacaine alone or ropivacine with clonidine. The secondary outcomes were pain score at rest and movement, total analgesic requirement, sedation score and postoperative nausea and vomiting.

RESULTS

The mean pain free periods were 20min, 384.76min and 558.09min for Group S, Group R and Group RC, respectively and this difference was statistically significant (p < 0.001). There was no significant difference between Group R and Group RC in terms of pain scores at rest and movement and total analgesic requirement.

CONCLUSION

Addition of clonidine to ropivacaine in USG guided adductor canal block led to significant prolongation of pain free period though pain score at rest and movement, and rescue analgesic requirement, did not differ.

Adjuvants to local anesthetics: Current understanding and future trends

Although beneficial in acute and chronic pain management, the use of local anaesthetics is limited by its duration of action and the dose dependent adverse effects on the cardiac and central nervous system. Adjuvants or additives are often used with local anaesthetics for its synergistic effect by prolonging the duration of sensory-motor block and limiting the cumulative dose requirement of local anaesthetics. The armamentarium of local anesthetic adjuvants have evolved over time from classical opioids to a wide array of drugs spanning several groups and varying mechanisms of action. A large array of opioids ranging from morphine, fentanyl and sufentanyl to hydromorphone, buprenorphine and tramadol has been used with varying success. However, their use has been limited by their adverse effect like respiratory depression, nausea, vomiting and pruritus, especially with its neuraxial use. Epinephrine potentiates the local anesthetics by its antinociceptive properties mediated by alpha-2 adrenoreceptor activation along with its vasoconstrictive properties limiting the systemic absorption of local anesthetics. Alpha 2 adrenoreceptor antagonists like clonidine and dexmedetomidine are one of the most widely used class of local anesthetic adjuvants. Other drugs like steroids (dexamethasone), anti-inflammatory agents (parecoxib and lornoxicam), midazolam, ketamine, magnesium sulfate and neostigmine have also been used with mixed success. The concern regarding the safety profile of these adjuvants is due to its potential neurotoxicity and neurological complications which necessitate further research in this direction. Current research is directed towards a search for agents and techniques which would prolong local anaesthetic action without its deleterious effects. This includes novel approaches like use of charged molecules to produce local anaesthetic action (tonicaine and n butyl tetracaine), new age delivery mechanisms for prolonged bioavailability (liposomal, microspheres and cyclodextrin systems) and further studies with other drugs (adenosine, neuromuscular blockers, dextrans).

Multilevel Thoracic Paravertebral Block Using Ropivacaine With/Without Dexmedetomidine in Video-Assisted Thoracoscopic Surgery

OBJECTIVES

Thoracic paravertebral block (TPVB) is reported to have advantages in postoperative pain management in unilateral thoracic surgeries. Previous studies have demonstrated that dexmedetomidine could be used as an adjuvant to local anesthetics, with the aim of prolonging the duration of neural blockade. However, little is known about whether such a combination could improve the quality of postoperative analgesia compared with local anesthetic only when TPVB is used for patients undergoing video-assisted thoracoscopic surgery (VATS).

DESIGN

A prospective, randomized, controlled study.

SETTING

Single-center university hospital.

PARTICIPANTS

The study included 60 patients undergoing VATS under general anesthesia.

INTERVENTIONS

The patients were allocated randomly into the following 2 groups: 0.375% ropivacaine, 20 mL only (group R, n = 30), and 0.375% ropivacaine, 20 mL plus 1 μg/kg of dexmedetomidine (group RD, n = 30). At the end of surgery, TPVB guided using ultrasound was performed at 4 points-T4-5, T5-6, T6-7, and T7-8-of the surgical side; 5 mL of solution were injected at each point. Postoperatively, the intravenous nonsteroidal anti-inflammatory drug flurbiprofen was used as part of multimodal analgesia.

MEASUREMENTS AND MAIN RESULTS

Pain scores at rest and during coughing were evaluated by a blinded observer in the postanesthesia care unit postoperatively at 1, 2, 4, 8, 12, 24, 36, and 48 hours, and the dermatomal levels of sensory blockade, postoperative requirements for rescue analgesia, adverse events, and patient satisfaction also were recorded. There was a significant reduction in postoperative pain scores at rest starting from the postoperative 8th hour until the 48th hour and during coughing starting at the postoperative 4th hour until the 48th hour in the group RD compared with those in group R (p = 0.043). The dermatomal levels of sensory blockade were comparable in the 2 groups. Patient satisfaction after surgery was significantly higher in the group RD than in group R (p < 0.001). Total consumption of the intravenous rescue analgesic morphine and adverse events were not significantly different between the 2 groups.

CONCLUSIONS

Compared with ropivacaine only, the addition of dexmedetomidine, 1 μg/kg, to local anesthetic for multilevel TPVB in patients undergoing VATS prolonged the duration of postoperative analgesia and improved patient satisfaction without serious side effects when combined with postoperative intravenous nonsteroidal anti-inflammatory drug administration.

Effect of Midazolam and Dexmedetomidine Sedation on the Onset and Duration of Supraclavicular Brachial Plexus Block: A Randomised Comparative Study

Objective

Prolonging the duration of sensory blockade with bupivacaine following supraclavicular brachial plexus block is desirable for improved postoperative pain management. This study was conducted to assess the effect of intravenous dexmedetomidine on the onset and duration of supraclavicular brachial plexus block using bupivacaine.

Methods

Sixty ASA I and II adult patients undergoing upper limb surgery under supraclavicular brachial plexus block were included in this prospective, randomised, double-blind study. They were randomly divided into two groups. The first group was administered midazolam at an initial dose of 0.04 mg kg^-1 in 10 mL of normal saline infused over 10 min, which was followed by maintenance infusion of 0.04 mg kg^-1 h^-1. The second group was administered 0.5 μg kg^-1 of dexmedetomidine in 10 mL of normal saline infused over 10 min, which was followed by maintenance infusion of 0.5 μg kg^-1 h^-1. Twenty-five millilitres of bupivacaine (0.5%) was injected for supraclavicular brachial plexus block.

Results

The onset of sensory block (16.6±1.9 vs. 19.8±1.7 min) and motor block (19.5±2.7 vs. 23.6±1.4 min) was significantly faster in the dexmedetomidine group than in the midazolam group (p<0.001). The duration of sensory block (738±66.3 vs. 307.7 ±46.7 min) and motor block (645.0±106.0 vs. 268.8±32.7 min) was significantly higher in the dexmedetomidine group than in the midazolam group (p<0.001).

Conclusion

Intravenous dexmedetomidine in combination with 25 mL of bupivacaine (0.5%) accelerated the onset of sensory and motor block and prolonged the duration of sensory and motor block when used for brachial plexus block, without resulting in any adverse events.

Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis

Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits.

Vibration sensation as an indicator of surgical anesthesia following brachial plexus block

Background:

Local anesthetic instillation in close vicinity to nerves anywhere in body blocks sensations in the same order as in central neuraxial blockade. The main purpose of this study was to evaluate the efficacy of vibration sense as criteria to determine the onset of surgical anesthesia following brachial plexus block and its correlation with loss of sensory and motor power.

Materials and Methods:

This prospective study included fifty patients of American Society of Anaesthesiologist physical status I and II, aged between 18 and 45 years, undergoing elective upper limb surgery under brachial plexus block by supraclavicular approach. The baseline values of vibration sense perception using 128 Hz Rydel–Seiffer tuning fork, motor power using formal motor power of wrist flexion and wrist extension, and sensory score by pinprick method were recorded preoperatively and every 5 min after giving block till the onset of complete surgical anesthesia.

Results:

The mean ± standard deviation of time (in minutes) for sensory, motor, and vibration block was 13.33 ± 3.26, 21.10 ± 3.26, and 25.50 ± 2.02, respectively (P < 0.05). Although all the patients achieved complete sensory and motor block after 25 min, 14% of the patients still had vibration sensations intact and 100% of the patients achieved complete sensory, motor, and vibration block after 30 min.

Conclusions:

Vibration sense serves as a reliable indicator for the onset of surgical anesthesia following brachial plexus block. Vibration sense testing with 128 Hz Rydel–Seiffer tuning fork along with motor power assessment should be used as an objective tool to assess the onset of surgical anesthesia following brachial plexus block.

Regional Anesthesia: Preferred Technique for Venodilatation in the Creation of Upper Extremity Arteriovenous Fistulae

Owing to the overall poor medical health of patients with end-stage renal disease, we have sought alternatives to the use of general anesthesia for access procedures. Furthermore, since local anesthesia (1) does not offer the motor block that is sometimes desired and (2) can be difficult to maintain when a large amount of vein needs to be transposed, we examined whether regional blocks can be useful for the creation of new arteriovenous fistulae (AVF).

From August 2002 to January 2005, 41 patients scheduled for AVF placement underwent a regional block with the use of a lidocaine and ropivacaine mixture using a nerve stimulator. Either axillary, interscalene, or infraclavicular blocks or a combination was used. Intraoperative duplex ultrasonography was used to assess the degree of venodilatation of the basilic and cephalic veins before and after the block. The site of each measurement was marked on the skin and selected by a clearly identifiable branch point. Each measurement was recorded three times and was made in the (1) native state, (2) after application of a tourniquet with opening and closing of the hand for 15 seconds, and (3) after placement of the block.

The average age of the patients was 65 ± 14 years (SD), with ages ranging from 33 to 91 years, and the prevalence of diabetes mellitus was 50%. Complete brachial plexus block was achieved in 34 patients (83%). Sensory block was accomplished within 10 to 15 minutes and usually lasted 4 to 6 hours. Motor block was accomplished in 10 to 25 minutes. Venodilatation was not noted in patients whose blocks did not work ( n = 7) or whose vein was found to be phlebitic on exploration ( n = 3). The degree of venodilatation noted as a percentage increase after application of the tourniquet compared with the native state for these 34 patients (in whom the block worked) was 37% for the distal cephalic, 31% for the midcephalic, and 32% for the midbasilic vein. The degree of venodilatation noted as a percentage increase after placement of the block compared with after tourniquet application for these 34 patients was 42% for the distal cephalic, 19% for the midcephalic, and 26% for the midbasilic vein. No instances of systemic toxicity, hematomas, or nerve injury from the block were noted. Accesses placed included 20 radiocephalic AVF, 8 brachiobasilic AVF, 8 brachiocephalic AVF, 2 arteriovenous grafts, 2 radiobasilic AVF, and 1 brachial vein AVF.

Regional block is a safe and, in our opinion, preferred technique for providing anesthesia for upper extremity vascular surgery. The venodilatation observed is augmented compared with that using a tourniquet and may allow more options for access placements.

Comparative evaluation of ropivacaine and ropivacaine with dexamethasone in supraclavicular brachial plexus block for postoperative analgesia

BACKGROUND

Mixing of various adjuvants has been tried with local anesthetics in an attempt to prolong anesthesia from peripheral nerve blocks but have met with inconclusive success. More recent studies indicate that 8 mg dexamethasone added to perineural local anesthetic injections augment the duration of peripheral nerve block analgesia.

AIMS

Evaluating the hypothesis that adding dexamethasone to ropivacaine significantly prolongs the duration of analgesia in supraclavicular brachial plexus block compared with ropivacaine alone.

PATIENTS AND METHODS

It was a randomized, prospective, and double-blind clinical trial. Eighty patients of ASA I and II of either sex, aged 16-60 years, undergoing elective upper limb surgeries were equally divided into two groups and given supraclavicular nerve block. Group R patients (n = 40) received 30 ml of 0.5% ropivacaine with distilled water (2 ml)-control group whereas Group D patients (n = 40) received 30 ml of 0.5% ropivacaine with 8 mg dexamethasone (2 ml)-study group. The primary outcome was measured as duration of analgesia that was defined as the interval between the onset of sensory block and the first request for analgesia by the patient. The secondary outcome included maximum visual analogue scale (VAS), total analgesia consumption, surgeon satisfaction, and side effects.

RESULTS

Group R patients required first rescue analgesia earlier (557 ± 58.99 min) than those of Group D patients (1179.4 ± 108.60 min), which was found statistically significant in Group D (P < 0.000). The total dose of rescue analgesia was higher in Group R as compared to Group D, which was statistically significant (P < 0.00).

CONCLUSION

Addition of dexamethasone (8 mg) to ropivacaine in supraclavicular brachial plexus approach significantly and safely prolongs motor blockade and postoperative analgesia (sensory) that lasted much longer than that produced by local anesthetic alone.

Additives to local anesthetics for peripheral nerve blocks or local anesthesia: a review of the literature

SUMMARY 

A multitude of studies have focused on individual additives to local anesthetics and their effect on quality, onset, duration, spread and selectivity, as well as the potential toxic effects of their use. This review aims to give a broad overview of the current evidence in this developing field, based on beneficial and adverse effects of these drugs. We discuss the limitations of the available data and hope to convey implications and future perspectives for clinicians and researchers alike.

Clonidine does not improve quality of ropivacaine axillary brachial plexus block in children

BACKGROUND

The addition of clonidine to peripheral nerve blocks is controversial in children.

OBJECTIVE

The aim of our study was to evaluate the effect of clonidine added to ropivacaine in pediatric axillary brachial plexus block (ABPB).

METHODS

Children aged 1-6 years, scheduled to undergo forearm or hand surgery, were recruited into this prospective, double-blind controlled trial. Patients were randomly allocated to receive an ABPB either with ropivacaine 0.2% 0.4 ml · kg(-1) plus saline in 1 ml (RS) or ropivacaine 0.2% 0.4 ml · kg(-1) plus clonidine 1 μg · kg(-1) in 1 ml (RC). Primary endpoints were quality of postoperative analgesia as assessed by pain scores and total 24-h postoperative analgesia requirements. Secondary outcomes were time to first analgesia request and duration of motor blockade.

RESULTS

Sixty patients were recruited (n = 30 per group) into the study. Pain scores were comparable throughout the first 24 h between the two groups. Ten children in the (RS) and six in (RC) groups required supplementary analgesia during the first 24 h (P = 0.24). Children who required further analgesia did so after 288 ± 94 min in the (RS) and 437 ± 204 min in the (RC) group (P = 0.06). There was no difference in the duration of motor block [186 ± 71 and 154 ± 56 min, P = 0.12 for (RS) and (RC), respectively].

CONCLUSION

Ropivacaine (0.2% 0.4 ml · kg(-1) ) for ABPB provides sufficient postoperative analgesia in children scheduled for forearm or hand surgery. The addition of clonidine to ABPB does not improve overall postoperative analgesia but may increase the time to first analgesia request.

Intra and postoperative outcome of adding clonidine to bupivacaine in infraorbital nerve block for young children undergoing cleft lip surgery

Aims and Context:

To evaluate the efficacy of adding clonidine to bupivacaine in bilateral infraorbital nerve block for hemodynamic changes, requirement of opioids, volatile agent, and muscle relaxants intraoperatively and relief of pain postoperatively

Setting and Design:

Prospective, randomized, double-blind study.

Methods:

Fifty pediatric patients aged less than 24 months undergoing elective cleft lip repair were randomly allocated to two groups of 25 each. After tracheal intubation, group A received bilateral infraorbital nerve block with 1 ml solution of clonidine (1 μg/kg) and bupivacaine 0.25%, and group B received 1 ml of 0.25% bupivacaine. Hemodynamic parameters, intraoperative requirement of volatile anesthetic agent, muscle relaxant, and analgesic were recorded. Pain was assessed postoperatively using the Face, Legs, Activity, Cry, Consolability scale till the first rescue drug was given.

Statistical Analysis:

Two sample unpaired t-test and the correlation r test.

Results:

The duration of analgesia from the time of administration of block in group A was 667.72 ± 210.74 min compared to 558.48 ± 150.28 min in group B (P<0.05).

Conclusion:

Addition of clonidine as an adjunct to local anesthetic significantly decreased the requirement of other anesthetic drugs and significantly prolonged the duration of postoperative analgesia without any adverse effects.

Local anaesthetic adjuvants: neuraxial versus peripheral nerve block

PURPOSE OF REVIEW

To present a review of the literature on the importance and the clinical characteristics relevant to adjuvants added to local anaesthetics in neuraxial and peripheral nerve blocks.

RECENT FINDINGS

In neuraxial anaesthesia, both opioids and alpha-2 receptor agonists have beneficial effects. Intrathecally, fentanyl and sufentanil not only improve the postoperative analgesia but also make it possible to allow a decrease in the local anaesthetic dose. When clonidine or dexmedetomidine was added to intrathecal local anaesthetics, the regression of sensory, motor block increased dose-dependently and postoperative analgesia was prolonged. The potency of intrathecal clonidine: dexmedetomidine seems to be 10: 1. In peripheral nerve block, when opioid was combined with local anaesthetics, no increased improvement in analgesia was reported in comparison with systemic controls in most of the studies, except buprenorphine. Also clonidine is controversial as an analgesic adjuvant. Special factors, such as type of local anaesthetics, block of upper or lower limb, are important for its the beneficial effect. Other adjuvants, except neuraxial low-dose neostigmine, are of minor importance.

SUMMARY

Opioids and alpha-2 receptor agonists are important as neuraxial adjuvants to improve the quality of peroperative and postoperative analgesia in high-risk patients and in ambulatory procedures. In peripheral nerve blocks, however, some benefit is found only when clonidine is added to local anaesthetics under certain circumstances.

The effect of dexmedetomidine sedation on brachial plexus block in patients with end-stage renal disease

BACKGROUND AND OBJECTIVE

The study investigated the effect of intravenous dexmedetomidine on brachial plexus block in patients with end-stage renal disease sedated with dexmedetomidine or midazolam for the formation of arteriovenous fistula.

METHODS

A supraclavicular brachial plexus block was performed in 68 patients scheduled for an arteriovenous fistula formation. A successful block was achieved in 64 patients (94%). Sixty-four patients received either dexmedetomidine (loading dose 1 microg kg 10 min followed by infusion of 0.2-0.7 microg kg h) or midazolam (bolus dose 0.04 mg kg followed by infusion of 0.04-0.08 mg kg h). Three patients were excluded during the study. Finally, 61 patients were analysed, 32 in the dexmedetomidine group and 29 in the midazolam group. Administration of the study drug was started after achievement of a complete block. The duration of the motor and sensory block was assessed.

RESULTS

The motor and sensory block was longer in the dexmedetomidine group (11.9 +/- 3.8 vs. 9.4 +/- 3.4 h, P = 0.0085 and 9.4 +/- 3.4 vs. 7.3 +/- 2.8 h, P = 0.030, respectively).

CONCLUSION

A systemic administration of dexmedetomidine prolongs the duration of brachial plexus block.

Effects of clonidine on lidocaine-induced inhibition of axonal transport in cultured mouse dorsal root ganglion neurones

BACKGROUND

The alpha(2)-adrenoceptor agonist clonidine is used in combination with lidocaine for anaesthesia. Lidocaine inhibits axonal transport and neurite growth, whereas alpha(2)-adrenoceptor agonists have neurotrophic effects. Here we have investigated whether clonidine reduces lidocaine-induced inhibition of axonal transport in cultured mouse dorsal root ganglion neurones.

METHODS

Axonal transport of organelles and neurite growth were assessed by video microscopy in cells treated with clonidine and lidocaine for 1 h. Stable responses were achieved within this period.

RESULTS

Clonidine (10 and 100 microM) increased and lidocaine (10, 100 microM, and 1 mM) decreased axonal transport. The inhibitory effects of lidocaine were reduced by simultaneous treatment with clonidine. The actions of clonidine were antagonized by the alpha(2)-adrenoceptor antagonist yohimbine. Since clonidine was reported to block N-type channels, we further investigated the role of ion channels in the antagonistic action of clonidine on the lidocaine response. The action of lidocaine on axonal transport was not mimicked by the Na+ channel blocker tetrodotoxin and not blocked by the Na+ channel activator veratridine. The action of lidocaine was not blocked by the L-type Ca2+ channel blocker nifedipine, but was blocked by the N-type channel blocker omega-conotoxin MVIIA. These effects on axonal transport correlated with the effects on neurite growth.

CONCLUSIONS

Inhibition of axonal transport induced by lidocaine, which may be mediated by N-type channel activation, can be blocked by clonidine. Clonidine may alleviate the effects of lidocaine on neuronal dysfunction.

Clonidine and analgesic duration after popliteal fossa nerve blockade: randomized, double-blind, placebo-controlled study

BACKGROUND

We tested the hypothesis that 100 microg clonidine added to 0.375% bupivacaine would prolong the duration of analgesia from popliteal fossa nerve blockade.

METHODS

Ninety-nine patients scheduled for hospital admission after foot or ankle surgery entered this randomized, double-blind, placebo-controlled trial. Patients received a popliteal fossa block (nerve stimulator technique, via the posterior approach) using 30 mL 0.375% bupivacaine, with epinephrine. Patients were randomized to receive no clonidine, 100 microg clonidine IM, or 100 microg clonidine with bupivacaine for the popliteal block. Patients also received a combined spinal-epidural anesthetic, a saphenous nerve block, and postoperative IV patient-controlled analgesia. The primary outcome was patient-reported duration of analgesia.

RESULTS

Duration of analgesia was statistically longer in the block clonidine group (18 +/- 6 h for clonidine with bupivacaine vs 14 +/- 7 h for IM clonidine and 15 +/- 7 h for control, P = 0.016 for control vs clonidine with bupivacaine). Pain scores, analgesic use, and side effects attributable to pain management were similar among groups.

CONCLUSIONS

Clonidine significantly prolongs the analgesic duration after popliteal fossa nerve blockade with bupivacaine.

The Effects of Clonidine on Postoperative Analgesia After Peripheral Nerve Blockade in Children

BACKGROUND

The effect of clonidine on the duration of sensory blockade after peripheral nerve blockade is controversial. We evaluated the effects of clonidine on the duration of sensory and motor block and analgesia time in children who underwent a variety of peripheral nerve blocks.

METHODS

We reviewed the regional anesthesia database that contains data on children who underwent an infraclavicular, lumbar plexus, femoral, fascia iliaca or sciatic nerve block for postoperative analgesia at The Children's Hospital of Philadelphia between October 2002 and December 2005. Patients were prospectively followed after the nerve block.

RESULTS

Two hundred fifteen patients (47%) received either bupivacaine or ropivacaine local anesthetic (LA) and 220 (53%) a combination of local anesthetic and clonidine (LAC). The duration of sensory block was significantly longer in the LAC (17.2 +/- 5 h) compared with that in the LA group (13.2 +/- 5 h) (P = 0.0001). The increase in duration was independent from the type of peripheral nerve block, local anesthetic used and operation performed. The motor block duration was significantly longer in the LAC group (9.6 +/- 5 vs 4.3 +/- 4 h, P = 0.014). Two patients in the LAC and one in the LA group experience prolonged numbness (max 72 h). No paresthesia or dysesthesia was observed.

CONCLUSION

The addition of clonidine to bupivacaine and ropivacaine can extend sensory block by a few hours, and increase the incidence of motor blocks.

Dexamethasone Added to Lidocaine Prolongs Axillary Brachial Plexus Blockade

Different additives have been used to prolong regional blockade. We designed a prospective, randomized, double-blind study to evaluate the effect of dexamethasone added to lidocaine on the onset and duration of axillary brachial plexus block. Sixty patients scheduled for elective hand and forearm surgery under axillary brachial plexus block were randomly allocated to receive either 34 mL lidocaine 1.5% with 2 mL of isotonic saline chloride (control group, n = 30) or 34 mL lidocaine 1.5% with 2 mL of dexamethasone (8 mg) (dexamethasone group, n = 30). Neither epinephrine nor bicarbonate was added to the treatment mixture. We used a nerve stimulator and multiple stimulations technique in all of the patients. After performance of the block, sensory and motor blockade of radial, median, musculocutaneous, and ulnar nerves were recorded at 5, 15, and 30 min. The onset time of the sensory and motor blockade was defined as the time between last injection and the total abolition of the pinprick response and complete paralysis. The duration of sensory and motor blocks were considered as the time interval between the administration of the local anesthetic and the first postoperative pain and complete recovery of motor functions. Sixteen patients were excluded because of unsuccessful blockade. The duration of surgery and the onset times of sensory and motor block were similar in the two groups. The duration of sensory (242 +/- 76 versus 98 +/- 33 min) and motor (310 +/- 81 versus 130 +/- 31 min) blockade were significantly longer in the dexamethasone than in the control group (P < 0.01). We conclude that the addition of dexamethasone to lidocaine 1.5% solution in axillary brachial plexus block prolongs the duration of sensory and motor blockade.