Does clonidine 50 μg improve cervical plexus block obtained with ropivacaine 150 mg for carotid endarterectomy? A randomized, double-blinded study

Effect of Added Alpha 2 Agonists with Local Anaesthetic in Infraclavicular Brachial Plexus Block: A Comparative Study between Dexmedetomidine and Clonidine

Background

Many adjuvant drugs are added with local anesthetics to increase the quality of regional blocks.

Aim

To compare the effects of dexmedetomidine and clonidine added to bupivacaine in infraclavicular brachial plexus block in prolonging the duration of analgesia in patients undergoing orthopedic surgery of forearm or hand and also to compare the duration of sensory and motor block, sedation, and hemodynamic changes like bradycardia and hypotension in two groups.

Settings and Design

This was an observational study conducted in a tertiary care hospital.

Materials and Methods

A study was conducted among 60 patients admitted for elective upper limb surgeries under ultrasound-guided infraclavicular block. Patients who received bupivacaine 0.5% (20 mL) + Clonidine 1 μg.kg-1 were classified as Group A and those received bupivacaine 0.5% (20 mL) + dexmedetomidine 1 μg.kg-1 were classified as Group B.

Statistical Analysis

Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) software version 25.

Results

Duration of analgesia was significantly higher in Group B as compared to Group A (mean + standard deviation = 764 ± 17.573 min vs. 526 ± 9.958 min, respectively, P = 0.001). The mean time for onset of a sensory block as well as motor block was significantly less in Group B when compared to Group A (P = 0.001). The mean duration of both sensory block and motor block was higher in Group B as compared to Group A (P = 0.001).

Conclusions

The dexmedetomidine group (Group B) provides a quicker and prolonged analgesic action without major adverse effects.

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.

Clonidine used as a perineural adjuvant to ropivacaine, does not prolong the duration of sensory block when controlling for systemic effects: A paired, blinded, randomized trial in healthy volunteers

Background

Clonidine used as an adjuvant to ropivacaine have been shown to prolong the duration of peripheral nerve blocks. The mechanism of action remains unclear. We hypothesized, that clonidine used as an adjuvant to ropivacaine extends the duration of an adductor canal block (ACB) by a peripheral mechanism, compared to ropivacaine alone when controlling for systemic effects.

Methods

We conducted a paired, blinded, randomized trial in healthy volunteers. Participants received bilateral ACBs containing 20 ml ropivacaine 0.5% + 1 ml clonidine 150μg/ml in one leg and 20 ml ropivacaine 0.5% + 1 ml saline in the other leg. The primary outcome measure was duration of sensory block assessed by temperature sensation (alcohol swab). Secondary outcome measures were duration of sensory block assessed by: pinprick, maximum pain during tonic heat stimulation, warmth detection threshold and heat pain detection threshold.

Results

We enrolled 21 volunteers and all completed the trial. There was no difference in duration of sensory block assessed with an alcohol swab: Mean duration in the leg receiving ropivacaine + clonidine was 19.4h (SD 2.7) compared to 19.3h (SD 2.4) in the leg receiving ropivacaine + placebo with a mean difference of 0.1h (95% CI: -1.0 to 1.3), P = 0.83. No differences in block duration were detected when assessed by: Pinprick, mean difference 0.0 h (95% CI: -1.3 to 1.3), maximum pain during tonic heat stimulation, mean difference -0.7 h (95% CI: -2.1 to 0.8), warmth detection threshold, mean difference -0.1 h (95% CI: -1.8 to 1.6) or heat pain detection threshold, mean difference -0.2 h (95% CI: -1.7 to 1.4).

Conclusions

Administering clonidine perineurally as an adjuvant to ropivacaine in an ACB did not prolong the duration of sensory block in a setup controlling for systemic effects of clonidine.

Addition of clonidine to bupivacaine in transversus abdominis plane block prolongs postoperative analgesia after cesarean section

Background and Aims:

The aim was to compare duration of postoperative analgesia with addition of clonidine to bupivacaine in bilateral transversus abdominis plane (TAP) block after lower segment cesarean section (LSCS).

Material and Methods:

One hundred American Society of Anesthesiologists (ASA) grade I and II pregnant patients undergoing LSCS under spinal anesthesia were randomly divided to receive either 20 ml bupivacaine 0.25% (Group B; n = 50) or 20 ml bupivacaine+1ug/kg clonidine bilaterally (Group BC; n = 50) in TAP block in a double-blind fashion. The total duration of analgesia, patient satisfaction score, total requirement of analgesics in the first 24 h, and the side effects of clonidine such as sedation, dryness of mouth, hypotension, and bradycardia were observed. P < 0.05 was taken as significant.

Results:

In 99 patients analyzed, TAP block failed in five patients. Duration of analgesia was significantly longer in Group BC (17.8 ± 3.7 h) compared to Group B (7.3 ± 1.2 h; P < 0.01). Mean consumption of diclofenac was 150 mg and 65.4 mg in Groups B and BC (P < 0.01), respectively. All patients in Group BC were extremely satisfied (P < 0.01) while those in Group B were satisfied. Thirteen patients (28%) in Group BC were sedated but arousable (P = 0.01) compared to none in Group B. In Group BC, 19 patients complained of dry mouth compared to 13 in Group B (P = 0.121). None of the patients experienced hypotension or bradycardia.

Conclusion:

Addition of clonidine 1 μg/kg to 20 ml bupivacaine 0.25% in TAP block bilaterally for cesarean section significantly increases the duration of postoperative analgesia, decreases postoperative analgesic requirement, and increases maternal comfort compared to 20 ml of bupivacaine 0.25% alone.

Comparative Effects of Clonidine and Adrenaline with Lignocaine during Maxillary Infiltration Anaesthesia for Dental Extraction

INTRODUCTION

Lignocaine is a commonly used local anaesthetic in dental practice. Many practitioners use adrenaline (epinephrine) as additive with lignocaine, and some have used clonidine, instead of adrenaline. Both having benefits and limitations.

AIMS

Hence a study was undertaken in our department to evaluate the advantages and disadvantages of using (plain lidocaine local anaesthetic) versus (lidocaine with adrenaline as additive) versus (lidocaine with clonidine as additive).

STUDY DESIGN

Randomised, prospective, double blind study.

MATERIALS AND METHODS

Seventy five patients requiring extraction of maxillary molar teeth who fall under ASA I category were included and randomly divided into group - I (n=25) (Lignocaine), group - II (n=25) (Lignocaine ± Adrenaline) and group - III (n=25) (Lignocaine ± Clonidine). The observations recorded were, time of onset of anaesthesia, hemodynamic parameters, blood loss during procedure and duration of post operative analgesia.

STATISTICAL ANALYSIS

The statistical analysis was carried out using SPSS 16 software.

RESULTS

A statistically significant difference was seen in blood loss, being higher in group I and duration of anaesthesia, being shortest in group I. There was no statistical difference between the three groups amongst other parameters.

CONCLUSION

Adrenaline at 10 μg/ml and clonidine at 15 μg/ml can be safely used as additives with lignocaine, in maxillary infiltration anaesthesia for dental extraction; with addition of either of these two drugs, having an equal advantage over use of plain lignocaine; in terms of lower blood loss and longer duration of anaesthesia; but, with no difference in the onset of anaesthesia and with no significant hemodynamic changes.

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.

Regional anaesthesia for carotid endarterectomy

Summary Regional anaesthesia is a popular choice for patients undergoing carotid endarterectomy (CEA). Neurological function is easily assessed during carotid cross-clamping; haemodynamic control is predictable; and hospital stay is consistently shorter compared with general anaesthesia (GA). Despite these purported benefits, mortality and stroke rates associated with CEA remain around 5% for both regional anaesthesia and GA. Regional anaesthetic techniques for CEA have improved with improved methods of location of peripheral nerves including nerve stimulators and ultrasound together with a modification in the classification of cervical plexus blocks. There have also been improvements in local anaesthetic, sedative, and arterial pressure-controlling drugs in patients undergoing CEA, together with advances in the management of patients who develop neurological deficit after carotid cross-clamping. In the UK, published national guidelines now require the time between the patient's presenting neurological event and definitive treatment to 1 week or less. This has implications for the ability of vascular centres to provide specialized vascular anaesthetists familiar with regional anaesthetic techniques for CEA. Providing effective regional anaesthesia for CEA is an important component in the armamentarium of techniques for the vascular anaesthetist in 2014.

Regional anaesthesia techniques for carotid surgery: the state of art

PURPOSE

This review will analyse some aspects of regional anaesthesia (RA) for carotid endarterectomy (CEA), a surgical procedure which requires a strict monitoring of patient's status. RA remains an important tool for the anaesthesiologist. Some debates remain about type and definition of regional anaesthesia, efficacy and safety of the different cervical block techniques, the right dose, concentration and volume of local anaesthetic, the use of adjuvants, the new perspectives: ultrasonography, the future directions.

METHODS

A literature search was performed for journal articles in English language in the PubMed Embase and in The Cochrane Library database, from January 2000 to December 2013. The electronic search strategy contained the following medical subject headings and free text terms: local anaesthesia versus general anaesthesia for endarterectomy, superficial and deep cervical block, complications of cervical nerve block, ultrasound guidance of superficial and deep cervical plexus block.

CONCLUSIONS

The gold standard for RA will be achieved after overcoming a number of limitations by a more extensive use of ultrasonography, by combining general and regional anaesthesia, including conscious anaesthesia, by defining the appropriate volume, concentration and dosage of local agents and by addition of adjuvants.

Analgesic efficacy of bilateral superficial cervical plexus block administered before thyroid surgery under general anaesthesia

BACKGROUND

The use of regional anaesthesia in thyroid surgery remains controversial. This double-blind, randomized controlled study was conducted to evaluate the analgesic efficacy of bilateral superficial cervical plexus block (BSCPB) performed under general anaesthesia in patients undergoing total thyroidectomy.

METHODS

Eighty-seven consecutive consenting patients were randomized to receive a BSCPB with saline (Group P, n = 29), ropivacaine 0.487% (Group R, n = 29), or ropivacaine 0.487% plus clonidine 5 microg ml(-1) (Group RC, n = 29). Sufentanil was given during the intraoperative period for a 20% increase in arterial mean pressure or heart rate in a patient with a bispectral index between 40 and 60. All patients received 4 g of acetaminophen during the first 24 h after operation. The pain score was checked every 4 h and nefopam was given for pain score >4 on a numeric pain scale.

RESULTS

During surgery, the median sufentanil requirements were significantly reduced in Group RC compared with Groups R and P (0.32 vs 0.47 and 0.62 microg kg(-1); P < 0.0001). After surgery, the number of patients requiring nefopam within 24 h of surgery was significantly lower in Groups R and RC than in Group P (16 and 19 vs 25; P = 0.03). At post-anaesthetic care unit admission, median (range) pain scores were significantly lower in Groups R [3 (0-10)] and RC [3 (0-8)] than in Group P [5 (0-8), P = 0.03]. No major complications of BSCPB occurred during study.

CONCLUSIONS

BSCPB with ropivacaine and clonidine improved intraoperative analgesia. BSCPB with ropivacaine or ropivaciane and clonidine was effective in reducing analgesic requirements after thyroid surgery.