Effect of different doses of dexmedetomidine as adjuvant in bupivacaine -induced subarachnoid block for traumatized lower limb orthopaedic surgery: a prospective, double-blinded and randomized controlled study

Role of Dexmedetomidine and Clonidine With Hyperbaric Ropivacaine in Subarachnoid Block: A Comprehensive Review

Subarachnoid block (SAB), a fundamental technique in regional anesthesia, offers efficient anesthesia for various surgical procedures with advantages including rapid onset, reliable anesthesia, and reduced systemic effects compared to general anesthesia. Hyperbaric ropivacaine, a long-acting local anesthetic, has gained popularity due to its favorable pharmacokinetic profile and safety profile. However, to extend the duration and enhance the quality of anesthesia provided by hyperbaric ropivacaine, adjuvants such as dexmedetomidine and clonidine are frequently employed. This comprehensive review explores the roles of dexmedetomidine and clonidine as adjuvants to hyperbaric ropivacaine in SAB. It examines their pharmacological mechanisms, clinical efficacy, safety profiles, and comparative effectiveness in prolonging analgesia and enhancing anesthesia. The review synthesizes evidence from clinical studies to delineate the synergistic effects of these adjuvants, their impact on patient outcomes, and their potential advantages over traditional anesthesia techniques. Through a detailed analysis of current literature and clinical practices, this review aims to provide insights into optimizing the use of dexmedetomidine and clonidine in SAB protocols. It discusses clinical implications, offers recommendations for practice, and identifies future research directions to further enhance the efficacy and safety of SAB using these adjuvants.

The Effect of Different Doses of Intravenous Dexmedetomidine on the Properties of Subarachnoid Blockade: A Systematic Review and Meta-Analysis

Background

Dexmedetomidine is a sedative and analgesic medication which has gained an increased usage as an adjuvant to both general and regional anaesthesia in recent years. In this systematic review and meta-analysis, we examined the changes to the characteristics of subarachnoid block when accompanied with intravenous dexmedetomidine. Our aim is to evaluate the effects of different doses of intravenous dexmedetomidine on the sensory and motor blockade duration of a single shot spinal anaesthetic and the incidence of any associated side effects.

Methods

We searched published randomized clinical trials (RCTs) from January 1992 to April 2019 that investigated the use of IV dexmedetomidine with spinal anaesthesia. After considering our inclusion and exclusion criteria, we included 15 RCTs with 985 patients. We analyzed the duration of sensory and motor blockade and the related adverse effects in relation to different doses of IV dexmedetomidine.

Results

Intravenous dexmedetomidine, with loading dose of 1 mcg/kg, prolonged the sensory blockade duration of spinal anaesthesia by a mean difference of 49.6 min, P<0.001, and motor blockade duration by a mean difference of 44.7 min, P<0.001, while a loading dose of 0.5 mcg/kg prolonged the sensory blockade by a mean difference of 43.06 min, P<0.001, and motor blockade duration by a mean difference of 29.09 min, P<0.001. Dexmedetomidine-related side effects were higher in patients receiving larger doses; the incidence of bradycardia was higher (OR=3.53, P<0.001) and incidence of hypotension showed a 1.29 fold increase when compared to the control group (P=0.065).

Conclusion

The administration of intravenous dexmedetomidine in conjunction with spinal anaesthesia can significantly prolong the duration of both sensory and motor blockade. The use of larger loading doses of dexmedetomidine was associated with a larger side-effect profile with minimal beneficial changes when compared to lower loading doses.

Effect of different doses of intrathecal dexmedetomidine on hemodynamic parameters and block characteristics after ropivacaine spinal anesthesia in lower-limb orthopedic surgery: a randomized clinical trial

The study aims to compare the efficacy of different doses of intrathecal dexmedetomidine on hemodynamic parameters and block characteristics after ropivacaine spinal anesthesia in lower-limb orthopedic surgery. In a double-blind trial, 90 patients undergoing spinal anesthesia for lower-limb orthopedic surgery were included and then randomly assigned to three groups; dexmedetomidine 5 μg/kg, dexmedetomidine 10 μg/kg and placebo. Blood pressure, heart rate, and oxygen saturation were recorded in the three groups at the first 15 minutes and then every 15 to 180 minutes at recovery by a resident anesthesiologist, as well as sensory-motor block onset. The visual analog scale scores for the assessment of pain were recorded at recovery, and 2, 4, 6, and 12 hours postoperatively and the data were analyzed by Stata software. The onset and time to achieve sensory block to ≥ T8 were faster in the 10 μg/kg dexmedetomidine group than the other groups (P = 0.001). The Bromage score was higher in the 10 μg/kg dexmedetomidine group (P = 0.0001) with lower pain score as compared with the 5 μg/kg dexmedetomidine and placebo groups (P = 0.0001). Therefore, an increase in dexmedetomidine hastens the onset of sensory-motor block but not causes side effects. This study was approved by the Ethical Committee of Arak University of Medical Sciences in 2017 (Ethical Code: IR.ARAKMU.REC.1396.37), and the trail was registered and approved by the Iranian Registry of Clinical Trials in 2017 (IRCT No. IRCT2017070614056N12).

Comparison of the Effect of Bupivacaine in Combination with Dexmedetomidine with Bupivacaine Plus Placebo on Neonatal Apgar Score, Bispectral Index, and Sedation Level of Parturient Women

OBJECTIVES

In this study, we aimed to compare the effects of bupivacaine alone and in combination with dexmedetomidine on postoperative analgesia, neonatal Apgar score, and bispectral index (BIS), which has been shown to correlate with increased sedation and loss of consciousness in women undergoing cesarean section under spinal anesthesia.

METHODS

A total of 152 term parturient women scheduled to have elective cesarean section with American Society of Anesthesiologist (ASA) physical status I or II were allocated randomly into two groups to receive either bupivacaine plus placebo (BV group) or bupivacaine plus dexmedetomidine (BVD group). BIS, sedation scale scores, Apgar scores, and hemodynamic characteristics were recorded and statistically compared between the groups.

RESULTS

Onset of post-operative pain was delayed in the BVD group. Sedation score (Ramsay sedation section) was improved in the BVD group with the least values of 0 - 3 followed by 1 - 4. There was no significant difference in Apgar score between the two groups. Also, there was a significant distinction between the two groups in terms of BIS during cesarean section.

CONCLUSIONS

The use of intrathecal dexmedetomidine as an adjuvant to bupivacaine in cesarean surgeries provides better intra-operative and post-operative analgesia without any significant impact on Apgar scores or incidence of side effects.

Dexamethasone Compared to Dexmedetomidine as an Adjuvant to Local Anesthetic Mixture in Peribulbar Block for Vitreoretinal Surgery. A Prospective Randomized Study

BACKGROUND

Dexamethasone or dexmedetomidine may improve the quality of peribulbar block.

AIM

The aim of this study is to compare the effects of adding either dexamethasone or dexmedetomidine to peribulbar block on the efficacy, intraocular pressure (IOP), time to first analgesic request, total analgesic requirement, and side effects in patients undergoing vitreoretinal surgery.

DESIGN

This was a clinical prospective randomized study.

PATIENTS AND METHODS

One hundred and fifty adult patients scheduled for vitreoretinal surgery with peribulbar block were randomized into three groups (50 patients each). Group I received 3.5 ml of 0.5% bupivacaine and 3.5 ml of 2% lidocaine + 1 ml normal Saline. 4 mg dexamethasone and 25 μg dexmedetomidine in 1 ml were added to the local anesthetic mixture in Groups II and III respectively. Onset and duration of sensory and motor blocks, adequate time to start surgery, IOP, time to first request of rescue analgesia, total analgesic consumption, and side effects were recorded. The statistical software SPSS 16 was utilized for statistical analysis.

RESULTS

Dexamethasone and dexmedetomidine groups showed significantly prolonged duration of corneal anesthesia (234.07 ± 1.37 and 233.54.1.97 min respectively), prolonged lid and globe akinesia (194.27 ± 1.63 and 194.73 ± 2.35 min respectively) with prolonged time to first request of analgesia and less consumption of rescue analgesia as compared to control group (P < 0.05) with non significant differences between both groups (P > 0.05). The onset of corneal anesthesia as well as lid and globe akinesia were enhanced in dexmedetomidine group compared to the other two groups (P < 0.05). In addition, the measurement of IOP was significantly less in the dexmedetomidine group after 10 min. All the patients were hemodynamically stable with no side effects observed.

CONCLUSION

The addition of dexamethasone and dexmedetomidine to local anesthetic mixture in peribulbar block for vitreoretinal surgeries provided safe and effective block with prolonged duration and decreased requirements of postoperative analgesia with better quality for dexmedetomidine group regarding the fast onset of the block and reduced IOP.

Isobaric ropivacaine with or without dexmedetomidine for surgery of neck femur fracture under subarachnoid block

Background and Aims:

Dexmedetomidine has a promising role as an intrathecal adjuvant. However it's role as an adjuvant to ropivacaine has not been evaluated extensively. This study is designed to find out the effect of addition of dexmedetomidine 5 μg to isobaric ropivacaine 18.75 mg on block characteristics and hemodynamic parameters in patients undergoing surgeries for fracture neck of femur under subarachnoid block (SAB).

Material and Methods:

Sixty-one American Society of Anesthesiologists (ASA) Class I or II patients between 18–60 years undergoing surgeries for fracture neck of femur under SAB were recruited and randomized into two groups. Thirty patients in Group RN received 2.5 ml isobaric ropivacaine 0.75% (18.75 mg) with 0.5 ml normal saline (NS) to make a total volume of 3 ml, while 31 patients in Group RD received 2.5 ml isobaric ropivacaine 0.75% with dexmedetomidine 5 μg diluted with NS to make a total volume of 3 ml. The block characteristics, hemodynamic parameters, and side effects were recorded in both the groups.

Results:

Patients in Group RD had significantly longer duration of sensory block (202.90 ± 50.2 min) compared to Group RN (157.33 ± 31.6 min), P < 0.001. Time to first rescue analgesia request was significantly longer in the Group RD compared to Group RN (265.16 ± 71.4 min vs 203.67 ± 35.6 min, respectively) (P < 0.001). However, the sensory block onset, maximum block height, time to two dermatomal regression, and motor block intensity remained unaltered. Incidence of side effects like hypotension, bradycardia, nausea, vomiting, and shivering were statistically similar in both the groups.

Conclusion:

Addition of 5 μg dexmedetomidine enhances the analgesic effect of intrathecal 18.75 mg isobaric ropivacaine for the conduct of fracture neck of femur surgeries with minimal adverse events.

Comparison of dexmedetomidine and fentanyl as local anesthetic adjuvants in spinal anesthesia: a systematic review and meta-analysis of randomized controlled trials

Purpose

To compare the effects of dexmedetomidine (Dex) and fentanyl as adjuvants to local anesthetics in spinal anesthesia.

Methods

Two researchers independently searched the PUBMED, EMBASE, Cochrane library, and CBM for randomized controlled trials comparing the effects of Dex and fentanyl as adjuvants to local anesthetics for intrathecal injection.

Results

A total of 639 patients from nine studies were included in this meta-analysis. The results showed that Dex resulted in statistically significant longer duration of stable sensory block (mean difference [MD] =27.12; 95% confidence interval [CI] [9.89, 44.34], P<0.01, I²=97%), sensory block (standardized mean difference [SMD] =3.81; 95% CI [2.35, 5.27], P<0.01, I²=97%), motor block (SMD =3.64; 95% CI [2.19, 5.08], P<0.01, I²=97%), and pain free period (SMD =2.98; 95% CI [1.69, 4.27], P<0.01, I²=96%); reducing the incidence of pruritus (relative risk [RR] =0.15; 95% CI [0.06, 0.39], P<0.01, I²=0%) compared with fentanyl. However, the onset of sensory and motor block, the time to peak sensory level, and the incidence of hypotension and bradycardia, and the side effects (nausea, vomiting, shivering and respiratory depression) were not significantly different between Dex and fentanyl.

Conclusion

Compared to fentanyl, Dex as local anesthetics adjuvant in spinal anesthesia prolonged the duration of spinal anesthesia, improved postoperative analgesia, reduced the incidence of pruritus, and did not increase the incidence of hypotension and bradycardia.

Dexmedetomidine as a neuraxial adjuvant for prevention of perioperative shivering: Meta-analysis of randomized controlled trials

BACKGROUND

Dexmedetomidine, a highly selective α2-adrenoceptor agonist, has been investigated for anti-shivering effects in some trials. This current meta-analysis was conducted to evaluate the effectiveness of dexmedetomidine as a neuraxial adjuvant in preventing perioperative shivering.

METHODS

This systematic review and meta-analysis was registered in PROSPERO [www.crd.york.ac.uk/PROSPERO] with the unique identification number CRD42017055991. The electronic databases PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL) were searched to select high-quality randomized controlled trials (RCTs) that evaluated the anti-shivering efficacy for neuraxial application dexmedetomidine as local anesthetic adjuvant. Effects were summarized using pooled risk ratios (RRs), weighed mean differences (MDs), or standardized mean differences (SMDs) and corresponding 95% confidence intervals (Cls) with random effect model. Heterogeneity assessment, sensitivity analysis, and publication bias were performed. The primary outcome was perioperative shivering.

RESULTS

A total of 1760 patients from 24 studies were included in this meta-analysis. Compared with the placebo, dexmedetomidine reduced the incidence of perioperative shivering (RR: 0.34; 95% Cl: 0.21 to 0.55; P < 0.00001), with a maximum effective dose of 5μg via subarachnoid space injection (RR: 0.55; 95% CI: 0.32 to 0.92; P = 0.02), especially in cesarean section (RR: 0.20; 95% CI: 0.09 to 0.45; P = 0.0001). Dexmedetomidine also could improve the characteristics of the block, with an increase only in the incidence of bradycardia (RR: 2.11; 95% CI: 1.23 to 3.60; P = 0.006). No significant difference could be found compared dexmedetomidine with other adjuvants, except morphine.

CONCLUSIONS

This meta-analysis shows that dexmedetomidine as a neuraxial adjuvant had statistically significant efficacy on prevention of perioperative shivering. Moreover, dexmedetomidine could improve the characteristics of the block. However, the potential induction of bradycardia should be taken seriously.

Intrathecal magnesium sulfate as a spinal adjuvant in two different doses, combined with 0.5% heavy bupivacaine for infraumbilical surgeries

The spinal anesthesia has the definitive advantage that profound nerve block can be produced in a large part of the body by the relatively simple injection of a small amount of local anesthetic.