Local anaesthetic adjuvants: neuraxial versus peripheral nerve block. Curr Opin Anaesthesiol. 2009;22:649-654. [PMID: 19593120 DOI: 10.1097/aco.0b013e32832ee847]

Development of a Pericapsular Elbow Desensitization Technique in Dogs-A Canine Cadaveric Study

Peripheral nerve blocks play a critical role in pain management; however, no technique has been described to specifically target the articular nerve branches of the elbow in dogs. This study aimed to develop and compare the success rate of an ultrasound-guided versus a blind pericapsular elbow desensitization (PED) technique in canine cadavers. Phase I involved gross and ultrasonographic evaluations of the elbow joint in four cadavers to identify landmarks for the PED technique. Phase II compared the ultrasound-guided and blind PED techniques using dye injections in eight cadavers, followed by the dissection and histological analysis of stained tissues to confirm nerve involvement. The results demonstrated that four quadrant injections are required to target the articular branches of the radial, ulnar, median, and musculocutaneous nerves. The ultrasound-guided technique achieved a significantly higher overall success rate (77.5%) than the blind technique (45%, p = 0.005). While both techniques showed similar success rates (50-62.5%) for the ulnar, median, and musculocutaneous branches, the ultrasound-guided technique (100%) outperformed the blind technique for the cranial (37%, p = 0.02) and caudal (12.5%, p = 0.001) articular branches of the radial nerve. These findings provide a foundation for future clinical studies evaluating the ultrasound-guided PED technique in live animals.

Effect of dexmedetomidine constant rate infusion on the analgesic duration of peripheral nerve blocks in dogs: a randomized clinical study

The aim of this study was to evaluate whether a constant rate infusion of dexmedetomidine could prolong the analgesic effect of peripheral nerve blocks. Twenty client-owned dogs were enrolled and randomly divided into 2 groups. The DEX group received dexmedetomidine infusion at 1 mcg kg-1 h-1, and the NaCl group received an equivalent volume infusion of saline. Infusions were started after securing vascular access and continued for 10 min, after which intravenous (IV) methadone at 0.2 mg kg-1 and propofol to effect were administered. All animals were maintained with isoflurane in 70% oxygen. Sciatic, saphenous and obturator nerve blocks were performed using 0.1 mL kg-1 0.5% ropivacaine/block. Intraoperative fentanyl was administered if the heart rate and/or mean arterial pressure (MAP) increased > 15% from the previous measurement, and vasopressors were administered if MAP was ≤ 70 mmHg. Postoperative pain was assessed every hour using the Glasgow Composite Pain Scale (GCPS) until the first rescue analgesia administration. Postoperative rescue analgesia (methadone (0.2 mg kg-1 IV) and carprofen (2 mg kg-1 IV)) was administered if the pain score was higher than 6/24 or 5/20. Duration of analgesia was defined as the time between the nerve block procedure and initial postoperative rescue analgesia. Ambulation, proprioception, and skin sensitivity were evaluated to assess the duration of the motor and sensory block. A Student T and chi-square test were used to compare groups for duration of postoperative analgesia and intraoperative fentanyl and vasopressor use, respectively (p values ≤ 0.5 considered significant). A greater number of dogs in the NaCl group required fentanyl (5/10 p = 0.03) and vasopressors (8/10, p = 0.02) than did those in the DEX group (0/10 and 2/10, respectively). The duration of postoperative analgesia was significantly longer (604 ± 130 min) in the DEX group than in the NaCl group (400 ± 81 min, p = 0.0005).Dexmedetomidine infusion at 1 mcg kg-1 h-1 delays the time to first administration of rescue analgesia and reduces intraoperative analgesic and vasopressor requirements during Tibial Tuberosity Advancement surgery.

Comparative study of dexmedetomidine versus fentanyl as adjuvants to bupivacaine in ultrasound-guided transversus abdominis plane block in patients undergoing radical cystectomy: a prospective randomised study

Background

Transversus abdominis plane (TAP) block is beneficial for pain management after conducting abdominal surgery.

Objective

To compare the outcomes of dexmedetomidine and fentanyl, as adjuvants to bupivacaine, for ultrasound-guided TAP block analgesia among patients undergoing radical cystectomy for postoperative pain management.

Methods

This prospective, randomised, comparative study included a total of 60 patients, who underwent radical cystectomy. Participants were randomly divided into three categories with 20 subjects each; group B had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 2 ml normal saline; group BF had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 1 µg/kg fentanyl dissolved in 2 ml normal saline and group BD had patients who received a single shot US-guided TAP block on each side with 20 ml of 0.25% bupivacaine + 1 µg/kg dexmedetomidine dissolved in 2 ml normal saline.The researchers recorded the time taken for first rescue analgesia, total analgesic dose in the first 24 h after surgery, patient satisfaction, sedation score, and postoperative complications.

Results

The time taken for first rescue analgesia was significantly lengthier in group (BD) (8.90 ± 2.47) than (BF) (6.50 ± 1.43) and (B) (4.40 ± 1.05) groups. The total nalbuphine consumption, during the first 24 h, was significantly lower in (BD) (0.15 ± 0.00) group compared to (BF) (0.20 ± 0.07) and (B) (0.24 ± 0.08) groups.

Conclusion

In comparison with fentanyl, as an adjuvant to bupivacaine, dexmedetomidine was found to be associated with prolonged postoperative analgesia, less postoperative pain scores and low opioid consumption.

Trial registration

This study was registered at Clinical Trials.gov on 23 March 2020 (registration number: NCT04318158).

Clinical efficacy of dexmedetomidine combined with lidocaine for femoral and sciatic nerve blocks in dogs undergoing stifle surgery

OBJECTIVE

To evaluate the effects of dexmedetomidine administered perineurally or intramuscularly (IM) on sensory, motor function and postoperative analgesia produced by lidocaine for sciatic and femoral nerve blocks in dogs undergoing unilateral tibial tuberosity advancement surgery.

STUDY DESIGN

Prospective, blinded, clinical study.

ANIMALS

A group of 30 dogs.

METHODS

Dogs were anaesthetized with acepromazine, propofol and isoflurane in oxygen/air. Electrolocation-guided femoral and sciatic nerve blocks were performed: group L, 0.15 mL kg^-1 2% lidocaine (n = 10); group LD_loc, lidocaine and 0.15 μg kg^-1 dexmedetomidine perineurally (n = 10); group LD_sys, lidocaine and 0.3 μg kg^-1 dexmedetomidine IM (n = 10). After anaesthesia, sensory blockade was evaluated by response to forceps pinch on skin innervated by the saphenous/femoral, common fibular and tibial nerves. Motor blockade was evaluated by observing the ability to walk and proprioception. Analgesia was monitored with Short Form of Glasgow Composite Pain Scale for up to 4 hours after extubation. Methadone IM was administered as rescue analgesia. Data were analysed by linear mixed effect models and Kaplan-Meier test (p < 0.05).

RESULTS

Median duration of the sensory blockade for all nerves was longer (p < 0.001) for group LD_loc than for groups L and LD_sys and was longer (p = 0.0011) for group LD_sys than for group L. Proprioception returned later (p < 0.001) for group LD_loc [285 (221-328) minutes] compared with group L [160 (134-179) minutes] or LD_sys [195 (162-257) minutes]. Return of the ability to walk was similar among all groups. Dogs in group LD_loc required postoperative rescue analgesia later (p = 0.001) than dogs in groups LD_sys and L.

CONCLUSIONS AND CLINICAL RELEVANCE

Dexmedetomidine administered perineurally with lidocaine prolonged sensory blockade and analgesia during the immediate postoperative period. Systemic dexmedetomidine also prolonged the sensory blockade of perineural lidocaine.

Prospective Randomized Control Trial Comparing Effect of Dexamethasone Versus Fentanyl as Adjuvants to Intrathecal Bupivacaine for Orthopedic Surgery

Introduction Spinal anesthesia is the most consistent block for lower limb orthopedic surgeries. We conducted this randomized prospective study to evaluate comparative efficacy of intrathecal dexamethasone with fentanyl and normal saline as adjuvants to hyperbaric bupivacaine in spinal anesthesia administered to patients scheduled for lower limb orthopedic surgery. Materials and methods 105 patients scheduled for lower limb orthopedic surgeries under spinal anesthesia were included in this clinical trial. After randomization, patients received an intrathecal injection of hyperbaric bupivacaine (12.5 mg) with 4 mg of dexamethasone in group I, hyperbaric bupivacaine (12.5 mg) with 25 ug fentanyl with 0.5 ml of normal saline in group II and hyperbaric bupivacaine (12.5 mg) with normal saline (1 ml) in group III, so as to make volume of drug equal in all three groups. The observer evaluated the sensory and motor blocks and other parameters like time to self-void, stay in post-anesthesia care unit (PACU) and complications.  Results The total duration of sensory blockade was found to be 311.43, 197.86 and 115.29 minutes and motor blockade of 223.43, 163.86 and 83.0 minutes in groups I, II and III respectively. The PACU stay was 233.14, 173.86 and 93.00 minutes in groups I, II and III, respectively. The average time to self-void was 400.00, 315.29 and 203.00 in three groups, respectively. Conclusion Intrathecal dexamethasone seemed to be an effective adjuvant to spinal bupivacaine as it prolongs the duration of analgesia, stable hemodynamic profile with minimal side effects. Further studies are required to evaluate the optimum dose and long-term safety of intrathecal dexamethasone.

Comparison of analgesic efficacy of intrathecal 1% 2-chloroprocaine with or without fentanyl in elective caesarean section: A prospective, double-blind, randomised study

Background and Aims:

Preservative free 1% 2-chlorprocaine is a short acting local anaesthetic agent suitable for day care surgical procedures. Potentiation of analgesic action of intrathecal local anaesthetics by the addition of opioids is well known. In this study, we investigated the effect of intrathecal fentanyl as an adjuvant to 1% 2-chloroprocaine (2-CP) in parturients undergoing elective lower segment caesarean section (LSCS).

Methods:

This prospective randomised comparative study was performed on 150 healthy, term parturients planned for elective low risk LSCS, divided into two equal groups. The group CS received 1% preservative-free 2-CP 3 ml (30 mg) + 0.5 ml normal saline and group CF received 1% preservative-free 2-CP 3 ml (30 mg) + 0.5 ml fentanyl (25 μg) with a total volume of 3.5 ml intrathecally in both groups. The duration of sensory blockade, duration of motor blockade, maximum height of sensory block, haemodynamic parameters, quality of block, neonatal outcome, patient satisfaction and any side effects were recorded.

Results:

There were no significant differences in demographic characteristics, haemodynamic parameters, onset of sensory block, onset of motor block and duration of motor block between the groups. The duration of sensory block and duration of analgesia was statistically prolonged in group CF than group CS (P value < 0.0001). There was no statistical difference in the Apgar score of newborns in both groups. The adverse effects (hypotension, bradycardia, nausea/vomiting, shivering and transient neurological symptoms) were comparable in both the groups.

Conclusion:

The addition of fentanyl to 1% 2-chloroprocaine intrathecally prolonged the duration of sensory block and postoperative analgesia in patients undergoing LSCS.

The efficacy of dexamethasone on pain management for knee arthroscopy: A meta-analysis of randomized controlled trials

INTRODUCTION

The impact of dexamethasone on pain management for knee arthroscopy remains controversial. We conduct a systematic review and meta-analysis to explore the influence of dexamethasone for knee arthroscopy.

METHODS

We search PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through October 2018 for randomized controlled trials (RCTs) assessing the effect of dexamethasone on pain intensity for patients with dental implant. This meta-analysis is performed using the random-effect model.

RESULTS

Four RCTs involving 228 patients are included in the meta-analysis. Overall, compared with control group for knee arthroscopy, dexamethasone supplementation has no notable effect on pain scores at 4 to 6 hours (Std. MD = 0.99; 95% CI = -2.97 to 4.95; P = .62), but exerts significantly favorable promotion to pain scores at 12 hours (Std. MD = -1.06; 95% CI = -1.43 to -0.69; P < .00001), duration of block (Std. MD = 1.87; 95% CI = 0.65 to 3.10; P = .003), time to first analgesic requirement (Std. MD = 0.90; 95% CI = 0.51 to 1.29; P < .00001), analgesic consumption (Std. MD = -1.62; 95% CI = -2.31 to -0.93; P < .00001), and patient satisfaction (Std. MD = 1.15; 95% CI = 0.73 to 1.58; P < .00001).

CONCLUSIONS

Dexamethasone supplementation has importantly positive influence on pain control for knee arthroscopy.

Efficacy of Nalbuphine as an Adjuvant to Ropivacaine in Ultrasound-guided Supraclavicular Brachial Block: A Prospective Randomized Controlled Study

BACKGROUND

A brachial plexus block (BPB) provides anesthesia and analgesia with limited duration. Various opioids have been used as adjuvants of local anesthetics to improve the effects.

OBJECTIVE

The objective of this study was to evaluate the safety and effectiveness of nalbuphine used as an adjuvant to local anesthetic during the supraclavicular BPB.

MATERIALS AND METHODS

In this prospective, double-blinded, randomized controlled study, 90 American Society of Anesthesiology (ASA) Physical Status I and II patients (aged 20 to 65 y) of either sex undergoing upper limb orthopedic surgeries under ultrasound-guided supraclavicular BPB were randomly allocated into 3 groups: group C (n=30), group NL (n=30), and group NH (n=30) for analyses. Each patient received 18 mL of 100 mg ropivacaine solution combined with 2 mL of normal saline, 2 mL of 10 mg nalbuphine, or 2 mL of 20 mg nalbuphine. The time of onset and block duration of sensory block (SB) and motor block (MB), duration of analgesia, hemodynamic variables, and any adverse effects were assessed.

RESULTS

Compared with group C, the onset time of both SB and MB were significantly shortened. The SB and MB duration were significantly prolonged in group NL and group NH. There was no significant difference between the duration of analgesia in group NL and NH although the analgesia duration of both groups was longer than group C. But the incidence of side effects in group NH such as vomiting was significantly higher than group NL.

CONCLUSIONS

Nalbuphine is an effective adjuvant to 0.5% ropivacaine in ultrasound-guided supraclavicular BPB. The dosage of 10 mg improves the quality of the anesthesia with less incidence of side effects.

A comparative study on the effect of addition of intrathecal buprenorphine to 2-chloroprocaine spinal anesthesia in short duration surgeries

Background and Aims

Spinal anesthesia is a safe and reliable technique for surgeries on the lower abdomen and lower limbs. Some of its characteristics like delayed ambulation and pain after block regression may limit its use, especially for short duration surgeries. 2-chloroprocaine is an amino-ester local anesthetic with an approximate duration of action of 40 minutes, which is ideal for short duration surgeries. This study aims to compare the effect of adding intrathecal buprenorphine to 2-chloroprocaine with regard to spinal anesthesia characteristics.

Material and Methods

After obtaining the institutional ethical committee clearance and clinical trial registration, informed consent was taken from 90 patients who were undergoing either lower abdominal or lower limb surgeries of less than 60 minutes duration and were then randomized into two groups. Group C received 40 mg of 1% 2-chloroprocaine and Group B received 40 mg of 1% 2-chloroprocaine with 60 mcg of buprenorphine. Sensory/motor block characteristics, first analgesic requirements, time to void, and unassisted ambulation were assessed. Student t test was used to analyze the metric parameters and Fisher's exact test was used to compare the categorical variables.

Results

The time of onset of sensory and motor blocks, peak sensory block, readiness for surgery, and complete regression of both sensory and motor blocks were comparable between the groups. Group B showed significantly prolonged duration of postoperative analgesia (855.82 ± 667.09 vs. 359.07 ± 253.3 minutes). 91.1% patients were able to ambulate within 100 minutes in our study.

Conclusion

We conclude that addition of buprenorphine to 2-chloroprocaine has a significant synergistic effect on prolonging postoperative analgesia.

Modified technique for thermal radiofrequency ablation of Thoracic dorsal root ganglia under combined fluoroscopy and CT guidance: a randomized clinical trial

Background

This study is comparing thermal radiofrequency ablation (TRFA) of the thoracic dorsal root ganglia (TDRG) guided by Xper CT and fluoroscopy with the standard fluoroscopy.

Methods

This randomized clinical trial included 78 patients suffering from chronic refractory pain due to chest malignancies randomly allocated into one of two groups according to guidance of TRFA of TDRG. In CT guided group (n = 40) TRFA was done under integrated Xper CT-scan and fluoroscopy guidance, while it was done under fluoroscopy guidance only in standard group (n = 38). The primary outcome was pain intensity measured by visual analog scale (VAS) score, functional improvement and consumption of analgesics. The secondary outcome measures were patient global impression of changes (PGIC) and adverse effects.

Results

VAS scores decreased in the two groups compared to baseline values (p < 0.001) and were lower in CT guided group up to 12 weeks. Pregabalin and oxycodone consumption was higher in the standard group at 1, 4 and 12 weeks (p < 0.001). Functional improvement showed near significant difference between the two groups (P = 0.06 at week 1, 0.07 at week 4 respectively) while the difference was statistically significant at week 12 (P = 0.04). PGIC showed near significant difference only at week 1 (P = 0.07) while the per-patient adverse events were lower in CT guided group (p = 0.027).

Conclusions

Integrated modality guidance with Xper CT-scan and fluoroscopy together with suprapedicular inferior transforaminal approach may improve efficacy and safety of TRFA of TDRG for the treatment of intractable chest pain in cancer patients.

Trial registration

The study was retrospectively registered at clinicaltrials.gov on 04/22/2018 (Registration No.: NCT03533413).

Adding sufentanil to ropivacaine in continuous thoracic paravertebral block fails to improve analgesia after video-assisted thoracic surgery: A randomised controlled trial

BACKGROUND

The benefit of adding opioid to a local anaesthetic for continuous thoracic paravertebral analgesia after video-assisted thoracic surgery (VATS) is unclear.

OBJECTIVES

To analyse the analgesic efficacy of ropivacaine and sufentanil in combination compared with ropivacaine alone after VATS.

DESIGN

A randomised, double-blinded, single-centre clinical trial.

SETTING

A tertiary university hospital between March 2010 and April 2014.

PATIENTS

Ninety patients were recruited, two were not included leaving 88 randomised into two groups. Eighteen patients were excluded from analysis and 70 completed the study.

INTERVENTION

To receive thoracic paravertebral analgesia with either 2 mg ml ropivacaine and 0.25 μg ml sufentanil (ropivacaine + sufentanil group) or 2 mg ml ropivacaine alone (ropivacaine group) for 48 h postoperatively. Infusion rate was set at 0.15 ml kg h in both groups.

MAIN OUTCOME MEASURES

The primary endpoint was the mean total amount of self-administered morphine by the patients in each group at 48 h postoperatively.

RESULTS

The mean ± SD total amount of self-administered morphine was not significantly different between groups (53.1 ± 27.2 mg in the ropivacaine + sufentanil group vs. 58.8 ± 34.3 mg in the ropivacaine group; P = 0.72). No significant differences were found between the two groups in either pain scores at rest or during movement, in opioid-related adverse reactions, in patient satisfaction or length of hospital stay.

CONCLUSION

Adding 0.25 μg ml sufentanil to 2 mg ml ropivacaine in continuous thoracic paravertebral analgesia for VATS did not reduce morphine consumption or pain scores when compared with ropivacaine alone. We cannot recommend its use for routine clinical practice. Further studies analysing different concentrations and infusion rates of sufentanil are needed before a lack of efficacy can be confirmed.

TRIAL REGISTRATION

Clinical trial registrations: EudraCT: 2009-014832-38. ClinicalTrials.gov: NCT 01082744.

Effects of intravenous dexmedetomidine infusion on local anaesthetic block: A spinal anaesthesia clinical model in dogs undergoing hind limb surgery

The aim of this randomised, prospective clinical trial was to determine how the administration of a low dose of dexmedetomidine (DEX) by IV constant rate infusion, modified the duration of the nerve block in dogs undergoing spinal anaesthesia (SA) in a clinical setting. Forty-four dogs undergoing hind limb orthopaedic surgery in a day-surgery regime, maintained under anaesthesia with isoflurane plus SA, were randomly assigned to receive 1 μg/kg/h (IV) of DEX (group D) or not (group C). Spinal anaesthesia was performed with a hyperbaric solution of bupivacaine and morphine at the L_5-6 interspace. Every mean arterial pressure (MAP) increase by 30% above the pre-skin incision value was considered an intraoperative analgesic failure and treated with a bolus of fentanyl as intraoperative rescue analgesia (iRA). Time free from iRA was analysed with a Kaplan-Maier survival curve. The ability to walk at 5 h from SA and the event of bradycardia (HR lower 60 beat per min) and hypotension (MAP value lower 60 mmHg) were recorded. The mean times at which iRA was required were 77.4 (3.2) in group C and 112.2 (8.6) in group D (Logrank test P = 0.038). In groups C and D hypotension incidence was 11/17 (65%) and 2/22 (9%), (P = 0.0004) and bradycardia 3/17 (18%) and 6/22 (27%) (P = 0.704), respectively. The ability to walk 5 h after SA was 14/14 (100%) and 13/14 (93%) in groups C and D, respectively. DEX infusion significantly prolonged the duration of the nociceptive nervous block without prolonging the motor block or increasing the bradycardia events.

Dexmedetomidine enhances ropivacaine-induced sciatic nerve injury in diabetic rats

BACKGROUND

Previous studies suggest that dexmedetomidine has a protective effect against local anaesthetic-induced nerve injury in regional nerve blocks. Whether this potentially protective effect exists in the context of diabetes mellitus is unknown.

METHODS

A diabetic state was established in adult male Sprague-Dawley rats with intraperitoneal injection of streptozotocin. Injections of ropivacaine 0.5%, dexmedetomidine 20 μg kg^-1 (alone and in combination), or normal saline (all in 0.2 ml) were made around the sciatic nerve in control and diabetic rats (n=8 per group). The duration of sensory and motor nerve block and the motor nerve conduction velocity (MNCV) were determined. Sciatic nerves were harvested at post-injection day 7 and assessed with light and electron microscopy or used for pro-inflammatory cytokine measurements.

RESULTS

Ropivacaine and dexmedetomidine alone or in combination did not produce nerve fibre damage in control non-diabetic rats. In diabetic rats, ropivacaine induced significant nerve fibre damage, which was enhanced by dexmedetomidine. This manifested with slowed MNCV, decreased axon density, and decreased ratio of inner to outer diameter of the myelin sheath (G ratio). Demyelination, axon disappearance, and empty vacuoles were also found using electron microscopy. An associated increase in nerve interleukin-1β and tumour necrosis factor-α was also seen.

CONCLUSIONS

Ropivacaine 0.5% causes significant sciatic nerve injury in diabetic rats that is greatly potentiated by high-dose dexmedetomidine. Although the dose of dexmedetomidine used in this study is considerably higher than that used in clinical practice, our data suggest that further studies to assess ropivacaine (alone and in combination with dexmedetomidine) use for peripheral nerve blockade in diabetic patients are warranted.

Efficacy of perineural dexamethasone with ropivacaine in thoracic paravertebral block for postoperative analgesia in elective thoracotomy: a randomized, double-blind, placebo-controlled trial

Purpose

The purpose of this study was to assess the efficacy of perineural dexamethasone with ropivacaine in multimodal analgesia for thoracic paravertebral block (TPVB) in patients undergoing elective thoracotomy.

Patients and methods

Ninety-six patients undergoing thoracotomy were enrolled in this trial and randomized to adjuvant therapy for TPVB: group S (saline), group R (0.5% ropivacaine), or group RD (5 mg dexamethasone and 0.5% ropivacaine). Postoperative analgesia, recovery duration, and chronic pain were recorded.

Results

Groups R and RD spent less time in the postanaesthesia care unit, had earlier out-of-bed activity, and had shorter postoperative hospital stays compared with group S. The RD group regained consciousness faster and had lower acute pain scores and used less patient-controlled analgesia during the first 72 h after surgery compared with group S. Postthoracotomy pain was decreased in group RD (19.0%) compared with group S (47.6%) 3 months postoperatively, p = 0.050.

Conclusion

Perineural dexamethasone with ropivacaine for TPVB improves postoperative analgesia quality, reduces recovery time, and may decrease the incidence of chronic pain after thoracotomy with an opioid-based anesthetic regimen.

Inhibition of Voltage-Gated Na+ Channels by Bupivacaine Is Enhanced by the Adjuvants Buprenorphine, Ketamine, and Clonidine

BACKGROUND AND OBJECTIVES

Regional anesthesia includes application of local anesthetics (LAs) into the vicinity of peripheral nerves. Prolongation or improvement of nerve blocks with LAs can be accomplished by coapplication with adjuvants, including buprenorphine, ketamine, and clonidine. While the mechanisms mediating prolonged or improved LA-induced effects by adjuvants are poorly understood, we hypothesized that they are likely to increase LA-induced block of voltage-gated Na channels. In this study, we investigated the inhibitory effects of the LA bupivacaine alone and in combination with the adjuvants on neuronal Na channels.

METHODS

Effects of bupivacaine, buprenorphine, ketamine, and clonidine on endogenous Na channels in ND7/23 neuroblastoma cells were investigated with whole-cell patch clamp.

RESULTS

Bupivacaine, buprenorphine, ketamine, and clonidine are concentration- and state-dependent inhibitors of Na currents in ND7/23 cells. Tonic block of resting channels revealed an order of potency of bupivacaine (half-maximal inhibitory concentration [IC50] 178 ± 8 μM) > buprenorphine (IC50 172 ± 25) > clonidine (IC50 824 ± 55 μM) > ketamine (IC50 1377 ± 92 μM). Bupivacaine and buprenorphine, but not clonidine and ketamine, induced a strong use-dependent block at 10 Hz. Except for clonidine, all substances enhanced fast and slow inactivation. The combination of bupivacaine with one of the adjuvants resulted in a concentration-dependent potentiation bupivacaine-induced block.

CONCLUSIONS

We demonstrate that buprenorphine, ketamine, and clonidine directly inhibit Na channels and that they potentiate the blocking efficacy of bupivacaine on Na channels. These data indicate that block of Na channels may account for the additive effects of adjuvants used for regional anesthesia.

The dose response of sufentanil as an adjuvant to ropivacaine in cesarean section for relief from somato-visceral pain under epidural anesthesia in parturients with scarred uterus

Visceral pain is common during epidural anesthesia with mini dose local anesthetics in parturients during cesarean section. To reduce or avoid this complication caused by traction on the abdominal viscera, this study aimed to determine the 50% effective dose (ED50) and 95% effective dose (ED95) of epidural sufentanil as an adjuvant combination with local anesthetics for relief visceral pain in parturients with scarred uterus undergoing elective cesarean section.One hundred parturients with scarred uterus undergoing elective cesarean section under epidural anesthesia were enrolled in this randomized, double-blinded, dose-ranging study. Parturients received 5, 10, 15, 20, and 25 μg epidural sufentanil as an adjuvant with 10 mL of 0.65% ropivacaine. Successful epidural anesthesia was defined as a sixth thoracic vertebra (T6) sensory level achieved within 20 minutes after epidural drugs administration and/or no visceral pain by traction on the abdominal viscera during the cesarean section. The ED50 and ED95 were calculated with a logistic regression model.ED50 and ED95 of epidural sufentanil for successful of the pain-free from visceral pain were 10.7 μg [95% confidence interval (CI): 2.4-14.4 μg) and 28.1 μg (95% CI: 19.4-44.0 μg), respectively. The onset time to sensory block, maximum Bromage scale and duration of motor block were significant different with dose of sufentanil >20 μg (P < .05, compared with the other dose groups). With the dose of epidural sufentanil >20 μg could result in an increase of incidence of maternals' adverse effects. Compared with a different dose of sufentanil, epidural administed sufentanil between 15 μg and 20 μg can maximize parturients' satisfaction.Our study showed that sufentanil could be used in combination with ropivacaine for relief from somato-visceral pain in patients with scarred uterus during elective cesarean section during epidural anesthesia, and that maximized parturients' satisfaction could be achieved when the use of sufentanil with the dose between 15 μg and 20 μg for epidural anesthesia.

Dexamethasone and Clonidine, but not Epinephrine, Prolong Duration of Ropivacaine Brachial Plexus Blocks, Cross-Sectional Analysis in Outpatient Surgery Setting

Objective

The primary aim of this study is to determine the effect of adding dexamethasone, clonidine or both with and without epinephrine to ropivacaine and bupivacaine brachial plexus blocks.

Design

Observational study of prospectively collected data.

Setting

Single academic outpatient surgery center.

Methods

We evaluated 5,515 patient entries who received brachial plexus block (BPB). Multiple, rescue, unsuccessful, and distal nerve blocks of the upper extremity were excluded. The duration was calculated from the time the block was performed until the resolution of the block by patient report. Block durations were compared using Analysis of Variance.

Results

After exclusions, 3,706 nerve blocks were analyzed. The median concentration of ropivacaine used was 0.5%. Both clonidine and dexamethasone significantly increased block duration by 1.1 and 3.0 hours, respectively. Combining clonidine and dexamethasone with ropivacaine increased block duration by 6.2 hours (p<0.001) when compared to ropivacaine alone. Dexamethasone and Clonidine increased block duration by 5.2 hours (p<0.001) when compared to clonidine alone and by 3.2 hours (p<0.001) compared to dexamethasone alone. The addition of epinephrine to any of the adjuvants made no statistically significant difference to the duration of action except when it was added to dexamethasone.

Summary

For brachial plexus blocks, epinephrine did not affect the duration of analgesia when added to ropivacaine. Epinephrine did not enhance the observed increase of block duration induced by clonidine or the combination of clonidine and dexamethasone. The most block duration enhancement was observed when combination of clonidine and dexamethasone were added to ropivacaine.

Effect of bupivacaine and adjuvant drugs for regional anesthesia on nerve tissue oximetry and nerve blood flow

Background

Nerve blood flow has a critical role in acute and chronic pathologies in peripheral nerves. Influences of local anesthetics and adjuvants on tissue perfusion and oxygenation are deemed as relevant factors for nerve damage after peripheral regional anesthesia. The link between low tissue perfusion due to local anesthetics and resulting tissue oxygenation is unclear.

Methods

Combined tissue spectrophotometry and laser-Doppler flowmetry were used to assess nerve blood flow in 40 surgically exposed median nerves in pigs, as well as nerve tissue oximetry for 60 min. After baseline measurements, test solutions saline (S), bupivacaine (Bupi), bupivacaine with epinephrine (BupiEpi), and bupivacaine with clonidine (BupiCloni) were applied topically.

Results

Bupivacaine resulted in significant decrease in nerve blood flow, as well as tissue oximetry values, compared with saline control. Addition of epinephrine resulted in a rapid, but nonsignificant, reduction of nerve blood flow and extensive lowering of tissue oximetry levels. The use of clonidine resulted in a reduction of nerve blood flow, comparable to bupivacaine alone (relative blood flow at T60 min compared with baseline, S: 0.86 (0.67-1.18), median (25th-75th percentile); Bupi: 0.33 (0.25-0.60); BupiCloni: 0.43 (0.38-0.63); and BupiEpi: 0.41(0.30-0.54). The use of adjuvants did not result in any relevant impairment of tissue oximetry values (saturation values in percent at T60, S: 91.5 [84-95]; Bupi: 76 [61-86]; BupiCloni: 84.5 [76-91]; and BupiEpi: 91 [56-92]).

Conclusion

The application of bupivacaine results in lower nerve blood flow, but does not induce relevant ischemia. Despite significant reductions in nerve blood flow, the addition of clonidine or epinephrine to bupivacaine had no significant impact on nerve tissue oximetry compared with bupivacaine alone. Nerve ischemia due to local anesthetics is not enhanced by the adjuvants clonidine or epinephrine.

Comparative Effects of Buprenorphine and Dexmedetomidine as Adjuvants to Bupivacaine Spinal Anaesthesia in Elderly Male Patients Undergoing Transurethral Resection of Prostrate: A Randomized Prospective Study

Background and Aims

Transurethral resection of the prostate is a commonly performed urological procedure in elderly men with spinal anaesthesia being the technique of choice. Use of low-dose spinal anesthetic drug with adjuvants is desirable. This study compares the sensorimotor effects of addition of buprenorphine or dexmedetomidine to low-dose bupivacaine.

Methods

Sixty patients were randomly allocated to three different groups. All received 1.8 mL 0.5% hyperbaric bupivacaine intrathecally. Sterile water (0.2 mL) or buprenorphine (60 μg) or dexmedetomidine (5 μg) was added to control group (Group C), buprenorphine group (Group B), and dexmedetomidine group (Group D), respectively. Time to the first analgesic request was the primary objective, and other objectives included the level of sensory-motor block, time to two-segment regression, time to S₁ sensory regression and time to complete motor recovery. ANOVA and post hoc test were used for statistical analysis. The value of P < 0.05 was considered statistically significant.

Results

All sixty patients completed the study. Postoperative analgesia was not required in the first 24 h in a total of 10 (50%), 12 (60%) and 15 (75%) patients in groups C, B, and D, respectively. Time to S₁ regression was 130 ± 46 min (Group C), 144 ± 51.3 min (Group B) and 164 ± 55.99 min (Group D), P = 0.117. Time to complete motor recovery was 177 ± 56.9 min (Group C), 236 ± 60 min (Group B) and 234 ± 61.71 min (Group D), P < 0.001.

Conclusion

Addition of buprenorphine (60 μg) or dexmedetomidine (5 μg) to intrathecal bupivacaine for transurethral resection prolongs the time to the first analgesic request with comparable recovery profile.

Efficacy of local dexmedetomidine add-on for spermatic cord block anesthesia in patients undergoing intrascrotal surgeries: randomized controlled multicenter clinical trial

Study objective

The objective of this study was to evaluate the effect of adding dexmedetomidine (DEX) to bupivacaine on the quality of spermatic cord block anesthesia and postoperative analgesia.

Design

This is a randomized, double-blind study.

Setting

This study was performed in an educational and research hospital.

Patients

One hundred twenty adult males were scheduled for intrascrotal surgeries.

Interventions

Patients were divided into two groups: group B received 10 mL of bupivacaine 0.25% for spermatic cord block and intravenous 50 µg of DEX and group BD received 10 mL of bupivacaine 0.25% added to 50 µg of DEX (9.5 mL bupivacaine 0. 25% + 0.5 mL [50 µg] DEX) for spermatic cord block, and for masking purposes, the patients received isotonic saline intravenously.

Measurements

Time to first analgesic request, analgesic consumption, and visual analog scale (VAS) pain score in the first 24 hours postoperatively were assessed.

Main results

Time to first rescue analgesic was significantly delayed in group BD in comparison with group B, median (interquartile) range, 7 (6–12) hours versus 6 (5–7) hours, (p=0.000), the mean cumulative morphine consumption (mg) in the first postoperative 24 hours was significantly lower in group BD compared with group B, 8.13±4.45 versus 12.7±3.79, with a mean difference (95% CI) of −4.57 (−6.06 to −3.07) (p=0.000); also, there was a significant reduction of VAS pain score in group BD in comparison with group B at all measured time points, VAS 2 hours (1.28±0.9 vs 1.92±0.8), VAS 6 hours (2.62±1.5 vs 3.93±1.2), VAS 12 hours (2.40±1.1 vs 3.57±0.65), VAS 24 hours (1.90±0.68 vs 2.53±0.62) (p=0.000)

Conclusion

The addition of 50 µg of DEX to bupivacaine 0.25% in spermatic cord block for intrascrotal surgeries resulted in delay of first analgesic supplementation, reduction of postoperative analgesic consumption as well as improvement of the success rate of the block.

Efficacy of perineural vs systemic dexamethasone to prolong analgesia after peripheral nerve block: a systematic review and meta-analysis

Perineural dexamethasone has gained popularity in regional anaesthesia to prolong the duration of analgesia, but its advantage over systemic administration is disputed. The objective of this meta-analysis was to compare the analgesic efficacy of both routes of administration during peripheral nerve block. The methodology followed the PRISMA statement guidelines. The primary outcome was the duration of analgesia analysed according to the type of local anaesthetic administered (bupivacaine or ropivacaine). Secondary outcomes included cumulative opioid consumption in morphine i.v. equivalents, pain scores, and complication rates (neurological complications, infection, or hyperglycaemia). Eleven controlled trials, including 914 patients, were identified. The duration of analgesia was significantly increased with perineural dexamethasone vs systemic dexamethasone by a mean difference of 3 h [95% confidence interval (CI): 1.4, 4.5 h; P=0.0001]. Subgroup analysis revealed that the duration of analgesia was increased by 21% with bupivacaine (mean difference: 4.0 h; 95% CI: 2.8, 5.2 h; P<0.00001) and 12% with ropivacaine (mean difference: 2.0 h; 95% CI: -0.5, 4.5 h; P=0.11). The quality of evidence for our primary outcome was moderate according to the GRADE system. There were no significant differences in other secondary outcomes. No neurological complications or infections were reported. Glucose concentrations were not increased when dexamethasone was injected systemically, but this outcome was reported by only two trials. There is, therefore, moderate evidence that perineural dexamethasone combined with bupivacaine, but not ropivacaine, slightly prolongs the duration of analgesia, without an impact on other pain-related outcomes, when compared with systemic dexamethasone. Injection of perineural dexamethasone should be cautiously balanced in light of the off-label indication for this route of administration.

Interventional Analgesic Management of Lung Cancer Pain

Lung cancer is one of the four most prevalent cancers worldwide. Comprehensive patient care includes not only adherence to clinical guidelines to control and when possible cure the disease but also appropriate symptom control. Pain is one of the most prevalent symptoms in patients diagnosed with lung cancer; it can arise from local invasion of chest structures or metastatic disease invading bones, nerves, or other anatomical structures potentially painful. Pain can also be a consequence of therapeutic approaches like surgery, chemotherapy, or radiotherapy. Conventional medical management of cancer pain includes prescription of opioids and coadjuvants at doses sufficient to control the symptoms without causing severe drug effects. When an adequate pharmacological medical management fails to provide satisfactory analgesia or when it causes limiting side effects, interventional cancer pain techniques may be considered. Interventional pain management is devoted to the use of invasive techniques such as joint injections, nerve blocks and/or neurolysis, neuromodulation, and cement augmentation techniques to provide diagnosis and treatment of pain syndromes resistant to conventional medical management. Advantages of interventional approaches include better analgesic outcomes without experiencing drug-related side effects and potential for opioid reduction thus avoiding central side effects. This review will describe various pain syndromes frequently described in lung cancer patients and those interventional techniques potentially indicated for those cases.

Perineural Nalbuphine in Ambulatory Upper Limb Surgery: A Comparison of Effects of Levobupivacaine with and without Nalbuphine as Adjuvant in Supraclavicular Brachial Plexus Block - A Prospective, Double-blinded, Randomized Controlled Study

Background and Aims:

Various opioid additives have been trialed to prolong brachial plexus block. We evaluated the effect of adding nalbuphine hydrochloride to levobupivacaine for supraclavicular brachial plexus blockade. The primary end-points were the onset and duration of sensory and motor blocks and duration of analgesia.

Materials and Methods:

Seventy-eight patients (aged 25–45 years) posted for ambulatory forearm and hand surgery under supraclavicular brachial plexus block were divided into two equal groups (Groups LN and LC) in a randomized, double-blind fashion. In Group LN (n = 39), 30 ml 0.5% levobupivacaine + 10 mg (diluted in 2 ml 0.9% saline) nalbuphine hydrochloride, and in Group LC (n = 39), 30 ml 0.5% levobupivacaine + 2 ml normal saline (0.9%) were administered in supraclavicular block. Sensory and motor block onset times and block durations, time to first analgesic use, total analgesic need, postoperative visual analog scale (VAS), hemodynamics, and side effects were recorded for each patient.

Results:

Although with similar demographic profile and block (sensory and motor) onset time, sensory and motor block duration and time to first analgesic use were significantly longer and the total need for rescue analgesics was lower in Group LN (P < 0.05) than Group LC. Postoperative VAS value at 24 h was significantly lower in Group LN (P < 0.05). Intraoperative hemodynamics was comparable between two groups, and no any appreciable side effect was noted throughout the study period.

Conclusion:

It can be concluded that adding nalbuphine hydrochloride to supraclavicular brachial plexus block increases the sensory and motor block duration and time to first analgesic use, and decreases total analgesic use with no side effects.

Transversus abdominis plane block as the primary anesthetic for peritoneal dialysis catheter surgery

STUDY OBJECTIVE

The primary goal of this study was to determine whether transversus abdominis plane (TAP) blocks were effective as the primary anesthetic technique for insertion and/or removal of peritoneal dialysis catheters.

DESIGN

This study is a descriptive case series investigation.

SETTING

Operating rooms at a tertiary care academic medical center.

PATIENTS

Twenty-four patients, American Society of Anesthesiologists (ASA) physical status 3 and 4, were included in this study.

INTERVENTIONS

Patients who had received a TAP block preoperatively for open surgical insertion or removal of a peritoneal dialysis catheter over a 26-month period with the intent of the block to serve as the primary anesthetic were included in this study.

MEASUREMENTS

Preoperative and intraoperative sedative medications and local anesthetic medications were analyzed. The primary outcome of the study was the ability of the TAP block to provide surgical anesthesia as determined by a lack of need to convert to general anesthesia (defined by placement of an airway device, use of volatile anesthetics, intraoperative propofol infusion dose equal to or greater than 100 μg kg(-1) min(-1)). Secondary outcomes included analysis of any complications from the higher concentrations of local anesthetics required for surgical block.

MANI RESULTS

Of 24 patients, 21 underwent the procedure without conversion to general anesthesia as defined above. No complications related to local anesthetics were found.

CONCLUSION

Transversus abdominis plane blockade can be successful at serving as the primary anesthetic modality for the insertion and/or removal of a peritoneal dialysis catheter by open-surgical approach. There were no systemic toxic effects or other complications recorded.

Addition of fentanyl to the ultrasound-guided transversus abdominis plane block does not improve analgesia following cesarean delivery

The present study aimed to investigate whether the addition of fentanyl to the transversus abdominis plane (TAP) block procedure may improve analgesic duration following cesarean delivery. A total of 147 nulliparous women with an American Society of Anesthesiologists physical status I-II, scheduled for elective cesarean delivery under spinal anesthesia, were enrolled in the present study. All patients underwent cesarean delivery under spinal anesthesia with 10 mg bupivacaine and 10 µg fentanyl, after which the patients underwent an ultrasound-guided bilateral TAP block with either 0.375% ropivacaine (group T_R; n=48), 0.375% ropivacaine and 50 µg subcutaneous fentanyl (group T_RS_F; n=49), or a mixture of 0.375% ropivacaine and 50 µg fentanyl (2.5 µg/ml; group T_RF; n=50) per side. The TAP block formed part of a multimodal analgesic regimen comprising patient-controlled analgesia (PCA) with intravenous fentanyl, and regular treatment with diclofenac and paracetamol. The TAP block was performed in the midaxillary line using an in-plane technique. The primary outcome was the time to the first PCA, whereas secondary outcomes were the cumulative and interval PCA consumptions, visual analogue scale (VAS) pain scores at rest and during movement, side effects assessed at 2, 6, 12, 24 and 48 h postoperatively, and patient satisfaction with postoperative analgesia. No significant differences were observed in the median time to the first PCA among the three groups (P=0.640), which were 150 min (70-720 min) in group T_R, 165 min (90-670 min) in group T_RS_F, and 190 min (70-680 min) in group T_RF. Fentanyl consumption, VAS pain scores, side effects and patient satisfaction were similar among the three groups; however, the demand for fentanyl was significantly decreased in the T_RS_F and T_RF groups at 2 h postoperatively (P=0.001 and 0.002, respectively), as compared with group T_R. No complications attributed to the TAP block were detected. In conclusion, the results of the present study suggested that the addition of 2.5 µg/ml fentanyl to the TAP block procedure was unable to improve analgesia following cesarean delivery under spinal anesthesia.

Efficacy of transverse abdominis plane block in reduction of postoperation pain in laparoscopic cholecystectomy

OBJECTIVE

Transversus abdominis plane (TAP) block is a recently introduced regional anesthesia technique that is used for postoperative pain reduction in some abdominal surgeries. The present study evaluated the efficacy of the TAP block on the post laparoscopic cholecystectomy pain intensity and analgesic consumption.

METHODS

Fifty-four patients were enrolled in three groups: TAP block with normal saline (Group 1, n = 18); TAP block with bupivacaine (Group 2, n = 18); and TAP block with bupivacaine plus sufentanil (Group 3, n = 18). The time to the first fentanyl request, fentanyl consumption in the 24 hours following surgery, and postoperative pain intensity at 30 minutes, 1 hour, 6 hours, 12 hours, and 24 hours following discharge for recovery were measured and recorded.

RESULTS

The total amount of 24-hour fentanyl consumption was higher in Group 1 (877.8 ± 338.8 μg) than either Group 2 (566.7 ± 367.8 μg) or Group 3 (555.5 ± 356.8 μg; p = 0.03). Postoperative pain score was higher in Group 1 than intervention groups (p = 0.006); however, there was no significant difference in intervention groups. The time to the first fentanyl request in Group 1 (79.44 ± 42.2) was significantly lower than Group 3 (206.38 ± 112.7; p = 0.001).

CONCLUSION

The present study demonstrated that bilateral TAP block with 0.5% bupivacaine reduces post laparoscopic cholecystectomy pain intensity and fentanyl request and prolongs time to the first analgesic request. Adding sufentanil to the block solution reduced neither pain intensity nor fentanyl further consumption.

Emulsified isoflurane enhances thermal transient receptor potential vanilloid-1 channel activation-mediated sensory/nociceptive blockade by QX-314

BACKGROUND

QX-314 produces nociceptive blockade, facilitated by permeation through transient receptor potential vanilloid-1 (TRPV1) channels. TRPV1 channel can be activated by noxious heat and sensitized by volatile anesthetics. The authors hypothesized that emulsified isoflurane (EI) could enhance thermal TRPV1 channel activation-mediated sensory/nociceptive blockade by QX-314.

METHODS

Rats were perineurally injected with QX-314 (Sigma-Aldrich Co. Ltd. Shanghai, China) alone or QX-314 combined with EI, followed by heat exposure on the injection site. The tail-flick and tail-clamping tests were used to assess sensory and nociceptive blockade, respectively; a sciatic nerve block model was used to assess motor and sensory blockade. Effects of EI on thermal activation of TRPV1 channels were evaluated on rat dorsal root ganglia neurons by whole-cell patch-clamp recordings.

RESULTS

Heat exposure enhanced sensory/nociceptive blockade by QX-314 in rat tails, but not motor blockade in sciatic nerve block model. QX-314 alone or QX-314 + 42°C produced no nociceptive blockade. QX-314 + 48°C produced 100% nociceptive blockade with duration of 12.5 ± 2.0 h (mean ± SEM). By adding 2% EI, QX-314 + 42°C produced 80% nociceptive blockade with duration of 8.1 ± 1.9 h, which was similar to the effect of QX-314 + 46°C (7.7 ± 1.1 h; P = 0.781). The enhancement of heat on sensory/nociceptive blockade of QX-314 was prevented by TRPV1 channel antagonist. The temperature thresholds of TRPV1 channel activation on dorsal root ganglia neurons were significantly reduced by EI.

CONCLUSIONS

Thermal activation of TRPV1 channels enhanced long-lasting sensory/nociceptive blockade by QX-314 without affecting motor blockade. The addition of EI reduced temperature thresholds for inducing long-lasting sensory/nociceptive blockade due to QX-314.

Methadone is a local anaesthetic-like inhibitor of neuronal Na+ channels and blocks excitability of mouse peripheral nerves

BACKGROUND

Opioids enhance and prolong analgesia when applied as adjuvants to local anaesthetics (LAs). A possible molecular mechanism for this property is a direct inhibition of voltage-gated Na(+) channels which was reported for some opioids. Methadone is an effective adjuvant to LA and was recently reported to inhibit cardiac Na(+) channels. Here, we explore and compare LA properties of methadone and bupivacaine on neuronal Na(+) channels, excitability of peripheral nerves, and cell viability.

METHODS

Effects of methadone were explored on compound action potentials (CAP) of isolated mouse saphenous nerves. Patch clamp recordings were performed on Na(+) channels in ND7/23 cells, the α-subunits Nav1.2, Nav1.3, Nav1.7, and Nav1.8, and the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2). Cytotoxicity was determined using flow cytometry.

RESULTS

Methadone (IC50 86-119 µM) is a state-dependent and unselective blocker on Nav1.2, Nav1.3, Nav1.7, and Nav1.8 with a potency comparable with that of bupivacaine (IC50 177 µM). Both bupivacaine and methadone also inhibit C- and A-fibre CAPs in saphenous nerves in a concentration-dependent manner. Tonic block of Nav1.7 revealed a discrete stereo-selectivity with a higher potency for levomethadone than for dextromethadone. Methadone is also a weak blocker of HCN2 channels. Both methadone and bupivacaine induce a pronounced cytotoxicity at concentrations required for LA effects.

CONCLUSIONS

Methadone induces typical LA effects by inhibiting Na(+) channels with a potency similar to that of bupivacaine. This hitherto unknown property of methadone might contribute to its high efficacy when applied as an adjuvant to LA.

Adjuvant dexamethasone for bupivacaine sciatic and ankle blocks: results from 2 randomized placebo-controlled trials

BACKGROUND AND OBJECTIVES

Dexamethasone as a local anesthetic adjuvant has been shown to prolong the time to first postoperative pain and improve postoperative analgesia following upper-limb brachial plexus block. However, the lack of systemically administered dexamethasone in controls makes interpretation of previous studies difficult. We performed 2 prospective, randomized, double-blind, placebo-controlled trials to test whether the addition of dexamethasone 8 mg to bupivacaine for sciatic and ankle blocks prolongs block duration, improving postoperative analgesia.

METHODS

One hundred twenty-six patients presenting for elective foot/ankle surgery under sciatic (n = 66) or ankle blocks (n = 60) received 30 mL bupivacaine 0.5% + dexamethasone 8 mg or saline 2 mL. Alternate solutions were administered by intramuscular injection into the ipsilateral thigh. Outcomes assessed at 24 and 48 hours included pain onset, numerically rated pain, and supplementary tramadol consumption.

RESULTS

For the sciatic study, fewer dexamethasone group patients experienced pain at 24 hours (13% vs 47%, P = 0.01), an effect supported by multiple post hoc analyses for pain from 20 to 34 hours. No benefit existed at 48 hours or at any time for the ankle block. For each study, pain-free survival curves for the first 48 hours were not significantly different between groups. Pooled analysis of the 2 individual studies further supported the absence of a significant dexamethasone effect: hazard ratio (0.81; 95% confidence interval, 0.58-1.53; P = 0.94). For both studies, there were no differences between groups for all other study outcomes including worst and average pain, the requirement for tramadol, and patient satisfaction.

CONCLUSIONS

Substitution of systemic dexamethasone for perineural dexamethasone during bupivacaine sciatic and ankle blocks had only a minor analgesic enhancing effect. Given recent animal studies showing dexamethasone neurotoxicity, the perineural route for dexamethasone administration requires reevaluation.

Comparison between intrathecal hyperbaric bupivacaine and levobupivacaine for ambulatory knee arthroscopy

AIM: To compare the effect of hyperbaric levobupivacaine and bupivacaine on the quality of the block, patient satisfaction, and discharge time in patients undergoing arthroscopic knee surgery under unilateral spinal anesthesia.

METHODS: One hundred and thirty-two patients, American Society of Anaesthesiologists I or II, scheduled for elective ambulatory knee arthroscopy were randomly assigned to four double-blind groups. To achieve a unilateral spinal block, Group BF received 5 mg of hyperbaric bupivacaine plus 20 μg of fentanyl intrathecally, Group LF received 5 mg of hyperbaric levobupivacaine plus 20 μg of fentanyl intrathecally, Group B received 5 mg of hyperbaric bupivacaine intrathecally, and Group L received 5 mg of hyperbaric levobupivacaine intrathecally. The level and duration of the sensory block, the intensity and duration of the motor block, the time to first analgesic requirement, and the time elapsed until the patient’s discharge were recorded. Hemodynamic values and adverse effects were also recorded.

RESULTS: The duration of time needed to reach the T12 dermatome level was significantly longer in Group L [7 (3-20) min] than in Group B [6 (3-12) min] (P = 0.006). The maximum sensory level reached on the side undergoing the operation was significantly higher in Group BF than in Group B (P < 0.05). The intensity of the motor blockade was greater in Group BF than in Group LF and L. Complete recovery from motor blockade occurred earlier in Groups LF [75 (45-165) min] and L [63 (35-120) min] than in Group BF [115 (60-180) min] (P < 0.05). The length of time needed for the sensory block to regress to the level of S2 was shorter in Group L (154 ± 50) than in Group BF (192 ± 66) (P < 0.05). The quality of the block was significantly lower in Group L than in Groups BF, LF and B (P = 0.012, P = 0.003, and P < 0.001, respectively). The time elapsed until Visual Analog Scale ≥ 4 was significantly shorter in Group L (110 ± 48) than in Groups BF (200 ± 60), LF (156 ± 61) and B (162 ± 52) (P < 0.05). The time elapsed until the patient’s discharge was shorter in Groups B (244 ± 54) and L (229 ± 55) than in Group BF (288 ± 64) (P = 0.021 and P = 0.001, respectively). There were no differences among the groups regarding hemodynamic parameters and adverse events, except for pruritus. The occurrence of pruritus was significantly more frequent in Groups BF and LF than in other groups.

CONCLUSION: In conclusion, 5 mg of hyperbaric bupivacaine and 5 mg of hyperbaric levobupivacaine plus 20 μg of fentanyl provided a better spinal anesthesia than 5 mg of hyperbaric levobupivacaine alone.

Ropivacaine, articaine or combination of ropivacaine and articaine for epidural anesthesia in cesarean section: a randomized, prospective, double-blinded study

BACKGROUND AND OBJECTIVES

Initiation of epidural anesthesia with long-lasting local anesthetics consumes a significant amount of time, which could be problematic in busy obstetric anesthesia suites. We have hypothesized that a combination of articaine and ropivacaine provides faster onset and even an early recovery of sensory-motor block characteristics.

METHODS

Sixty term parturients scheduled to have elective cesarean section were randomly allocated into three groups to receive either 20 mL 2% articaine (Group A), 10 mL 2% articaine + 10 mL 0.75% ropivacaine (Group AR) or 20 mL 0.75% ropivacaine (Group R) via lumbar epidural catheter. The onset time of sensory block to T₁₀, T₆ and maximum sensory block level, time to two segments regression from maximum sensory block level, onset time and duration of motor block were all recorded. Intraoperative and postoperative additional analgesic requirements were also recorded.

RESULTS

Demographic data were similar. The onset times of sensorial block to T₁₀ and T₆ were significantly shorter in Groups A and AR in comparison with Group R (p<0.05). The onset times of motor block were similar in all groups, but a more intense motor block was observed in Group R (p<0.05). Two segments regression time and motor block durations were significantly shorter in Groups A and AR in comparison with Group R (p<0.05). Intraoperative supplementary analgesic requirements were higher in Group A than in the other two groups (p<0.05).

CONCLUSION

A combination of 2% articaine and 0.75% ropivacaine for epidural anesthesia in a cesarean section should be preferred over epidural 0.75% ropivacaine alone.

The influence of adjuvants used in regional anesthesia on lidocaine-induced neurotoxicity in vitro

BACKGROUND

Neurotoxic properties of local anesthetics can rarely lead to irreversible neuronal damage as in cauda equina syndrome. Clinically, local anesthetics are often combined with adjuvants to improve or prolong the anesthetic effect, whereas the impact of such adjuvants on lidocaine-induced apoptosis is unclear. Therefore, we investigated the influence of different adjuvants on the neurotoxicity of lidocaine.

METHODS

Human neuroblastoma cells and primary rat astrocytes were incubated for 24 hrs with lidocaine at a toxic concentration alone and in combination with morphine, sufentanil, clonidine, epinephrine, neostigmine, ketamine, and midazolam. Subsequently, the rates of cell death and early apoptosis were measured by flow cytometry in neuroblastoma cells, whereas astrocyte viability was analyzed by mitochondrial activity assay. In addition, isobolograms were calculated to describe the additive effects of lidocaine with ketamine or midazolam, respectively.

RESULTS

Coadministration of lidocaine with sufentanil, clonidine, epinephrine, and neostigmine did not alter the rates of cell death compared with cells treated with lidocaine alone. Morphine improved the viability of astrocytes only at concentrations beyond those occurring clinically. In contrast, coincubation of lidocaine with ketamine or midazolam led to significantly increased rates of cell death. The combined toxicity of ketamine and lidocaine was additive, whereas the combined toxicity of midazolam and lidocaine was subadditive.

CONCLUSIONS

Sufentanil, clonidine, epinephrine, and neostigmine do not influence the neurotoxicity of lidocaine in vitro. Morphine may have some cytoprotective effect at concentrations greater than those seen intrathecally in humans. In contrast, ketamine and midazolam increase the neurotoxicity of lidocaine in vitro, presumably by additive induction of mitochondrial apoptosis.

Buprenorphine added to levobupivacaine enhances postoperative analgesia of middle interscalene brachial plexus block

PURPOSE

The aim of this study was to assess whether addition of epineural buprenorphine prolonged postoperative analgesia of middle interscalene brachial plexus block (MIB) with levobupivacaine.

METHODS

One hundred and fifty consenting adult patients, scheduled for shoulder arthroscopic surgery for a rotator cuff tear under MIB with 29.5 ml of 0.75 % levobupivacaine, were randomized to receive additionally either saline or intramuscular buprenorphine 0.15 mg or epineural buprenorphine 0.15 mg. Onset of sensory and motor blocks, duration of postoperative analgesia, and consumption of postoperative analgesics were compared among the groups.

RESULTS

There were significant (P < 0.05) differences in the onset and the duration of the sensory block and in the duration of postoperative analgesia. Duration of both sensory block and postoperative analgesia was longer (P < 0.05) in patients who had received epineural buprenorphine (856.1 ± 215.2 and 1,049.7 ± 242.2 min) than in patients who had received intramuscular buprenorphine (693.6 ± 143.4 and 820.3 ± 335.3 min) or saline (488.3 ± 137.6 and 637.5 ± 72.1 min). Requirement of postoperative rescue analgesics was lower in the epineural buprenorphine group than in the other two groups. Few complications occurred from MIB (<1 %) and none from buprenorphine.

CONCLUSIONS

Epineural buprenorphine prolonged postoperative analgesia of MIB more effectively than intramuscular buprenorphine, which suggests that buprenorphine acts at a peripheral nervous system site of action.

Opioid-free perioperative analgesia for hemicolectomy in a patient with opioid-induced delirium: a case report and review of the analgesic efficacy of the alpha-2 agonist agents

Surgical pain in patients with documented opioid-induced delirium can be difficult to treat. We present a case of a patient undergoing laparoscopic hemicolectomy effectively treated with an opioid-free, alpha-2 adrenoreceptor agonist analgesic regimen.

CASE REPORT

A 21-year-old woman with persistent abdominal pain presented to the operating room for laparoscopic hemicolectomy for redundant right colon. Her medical history included a recently diagnosed postoperative opioid-induced delirium. Epidural infusion with local anesthetic offered partial pain relief with sensory levels of T9-L2. With the addition of dexmedetomidine infusion in the immediate postoperative period, the patient was comfortable with pain scores of 1 to 2/10 on Numerical Rating Scale (NRS). On postoperative day 1, the infusion was discontinued and the clonidine, 12 μg/hours was added to the epidural bupivacaine. With increased sedation 48 hours later, neuraxial clonidine was discontinued in favor to transdermal clonidine 0.1 mg/week, which was maintained until hospital discharge. Pain scores were maintained at 2 to 3/10 on NRS for the next 3 days when increased abdominal distention because of abscess formation rendered a new surgical intervention. The analgesia for the exploratory laparoscopy was maintained using epidural clonidine and bupivacaine infusion as well as intravenous dexmedetomidine, which were maintained another 2 days. Pain scores remained minimal until discharged home 3 day later.

DISCUSSION

Nonopioid analgesic regimens are beneficial in patients at risk of postoperative cognitive dysfunction attributable to opioids. Successful postoperative analgesia was achieved in our patient by alternating various routes of administration of alpha-2 adrenoreceptor agonists.

Dexmedetomidine and clonidine inhibit the function of Na(v)1.7 independent of α(2)-adrenoceptor in adrenal chromaffin cells

PURPOSE

Besides being administered systemically for sedation and analgesia, α(2)-agonists such as dexmedetomidine and clonidine have been administered with intrathecal, epidural, or perineural injections, leading to an antinociceptive effect at the spinal cord or peripheral nerve level. However, the mechanism for this remains unclear. In the present study, we examined whether dexmedetomidine and clonidine could inhibit the function of tetrodotoxin-sensitive Na(+) channels, which play important roles in the generation of pain.

METHODS

Cultured bovine adrenal chromaffin cells expressing the tetrodotoxin-sensitive Na(v)1.7 Na(+) channel isoform were incubated in KRP buffer containing 2 μCi (22)NaCl for 5 min without or with dexmedetomidine or clonidine in the absence or presence of veratridine, α-scorpion venom, β-scorpion venom, Ptychodiscus brevis toxin-3 or ouabain. Cells were then washed and counted radioactively.

RESULTS

Dexmedetomidine and clonidine reduced veratridine-induced (22)Na(+) influx via Na(v)1.7 in a concentration-dependent manner (EC(50) = 50 μM and 530 μM), even in the presence of ouabain, an inhibitor of Na(+), K(+)-ATPase. Dexmedetomidine and clonidine shifted the concentration-response curve of veratridine for (22)Na(+) influx downward without altering the EC(50) of veratridine. Atipamezole and yohimbine, α(2)-antagonists, did not prevent the inhibition of veratridine-induced (22)Na(+) influx by dexmedetomidine. Dexmedetomidine and clonidine combined with lidocaine induced more inhibition of veratridine-induced (22)Na(+) influx than each drug did individually. Atipamezole and yohimbine did not prevent the lidocaine-enhancing effect of dexmedetomidine and clonidine.

CONCLUSION

Dexmedetomidine and clonidine inhibit the function of Na(v)1.7 independent of α(2)-adrenoceptor. These results may lead to a deeper understanding of the peripheral antinociceptive effects of α (2)-agonists.