Single dose intravenous dexmedetomidine prolongs spinal anesthesia with hyperbaric bupivacaine

No Difference between Spinal Anesthesia with Hyperbaric Ropivacaine and Intravenous Dexmedetomidine Sedation with and without Intrathecal Fentanyl: A Randomized Noninferiority Trial

To enhance the duration of single-shot spinal anesthesia, intrathecal fentanyl and intravenous dexmedetomidine are widely used as adjuvants to local anesthetics. This noninferiority trial evaluated whether hyperbaric ropivacaine alone can produce a noninferior duration of sensory block in comparison to hyperbaric ropivacaine with intrathecal fentanyl in patients under dexmedetomidine sedation. Methods. Fifty patients scheduled for elective lower limb surgery under spinal anesthesia were randomly assigned in a double-blind fashion to receive either hyperbaric ropivacaine 15 mg (Group R) or hyperbaric ropivacaine 15 mg with intrathecal fentanyl 20 μg (Group RF). Intravenous dexmedetomidine (1 μg/kg for 10 min, followed by 0.5 μg/kg/h) was administered in both groups. The primary outcome of this study was the time to two-dermatomal regression of sensory block. The noninferiority margin for the mean difference was −10 min. Characteristics of the block, intraoperative and postoperative side effects, postoperative pain score, and analgesic consumption were assessed as secondary outcomes. Results. There was no difference in the two-dermatomal regressions of sensory block between the two groups (Group R 70.4 ± 10.2 min, Group RF 71.2 ± 12.4 min, $p$  = 0.804) with a mean difference of 0.8 min (−7.2 to 5.6, 95% confidence interval). Thus, the noninferiority of hyperbaric ropivacaine alone was established. There were no significant differences in the secondary outcomes between the two groups. Conclusions. Under intravenous dexmedetomidine sedation, the duration of spinal anesthesia with hyperbaric ropivacaine alone was noninferior to that of hyperbaric ropivacaine with intrathecal fentanyl. This suggests that addition of intrathecal fentanyl to hyperbaric ropivacaine may not be necessary in patients receiving intravenous dexmedetomidine.

The Effect of Midazolam and Dexmedetomidine Sedation on Block Characteristic Following Spinal Bupivacaine: A Randomized Comparative Study

Background:

Dexmedetomidine is widely used as an adjunct to general as well as regional anesthesia.

Aims:

This study was conducted to compare and evaluate the synergistic effect of single intravenous (i.v.) bolus dose of dexmedetomidine with midazolam on spinal block duration, analgesia, and sedation in patients undergoing infra-umbilical surgeries.

Settings and Design:

Prospective, randomized, comparative, and double-blinded study.

Materials and Methods:

One hundred patients between 18 and 60 years of age of American Society of Anesthesiologists physical status I and II posted for elective infra-umbilical surgery under subarachnoid block were randomly divided into two groups (Group D and Group M). Patients of Group D received i.v. dexmedetomidine 0.5 μg.kg⁻¹ and of Group M received i.v. midazolam 0.05 mg.kg⁻¹ as premedication 5 min before spinal anesthesia over 10 min. Vital parameters, Ramsay sedation score, level of sensory and motor block, recovery time for sensory blockade, postoperative numerical rating scale, time of requirement of the first dose of postoperative rescue analgesic, and duration of analgesia were recorded and analyzed.

Statistical Analysis:

Chi-square test, t-test, and analysis of variance test were applied to analyze data using SPSS package for Windows.

Results and Conclusion:

Premedication with single i.v. dexmedetomidine prolonged the duration and increased the maximum upper level of only sensory component of spinal anesthesia (6.42 ± 3.21 vs. 4.8 ± 1.21 thoracic segments higher than with midazolam sedation). This property can be beneficial in preventing undesirable prolongation of motor block and facilitating early ambulation in shorter duration of infra-umbilical surgeries. In addition, dexmedetomidine slowed the regression of sensory block and increased the time of the first request of analgesic.

Effect of intrathecal dexmedetomidine versus intravenous dexmedetomidine on subarachnoid anesthesia with hyperbaric bupivacaine

Background and Aim:

Alpha-2 agonists such as dexmedetomidine when given intravenously or intrathecally as an adjuvant potentiate subarachnoid anesthesia. We studied the difference in subarachnoid anesthesia when supplemented with either intrathecal or intravenous dexmedetomidine.

Material and Methods:

Seventy-five patients posted for lower limb and infraumbilical procedures were enrolled for a prospective, randomized, double-blind, placebo-controlled study and divided into three groups: Group B (n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%bupivacaine + 0.2 mL sterile water; Group B_DexIT (n = 25) received intravenous 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL (5 μg) dexmedetomidine; Group B_DexIV (n = 25) received intravenous dexmedetomidine 1 μg/kg in 20 mL 0.9%N aCl over 10 min followed by intrathecal 2.4 mL 0.5%b upivacaine + 0.2 mL sterile water. Onset and recovery from motor and sensory blockade, and sedation score were recorded. Onset of sensory and motor blockade was assessed using Kruskal–Wallis test, whereas 2-segment regression and recovery was analyzed using ANOVA and post hoc Tukey's test to determine difference between the three groups. P value <0.05 was considered statistically significant.

Results:

Although onset of sensory and motor block was similar in the three groups, motor recovery (modified Bromage scale 1) and two-segment sensory regression was prolonged in Group B_DexIT > Group B_DexIV > Group B (P < 0.001). Patients in Group B_DexIT and Group B_DexIV were sedated but easily arousable.

Conclusion:

Intrathecal dexmedetomidine prolongs the effect of subarachnoid anesthesia with arousable sedation when compared with intravenous dexmedetomidine.

A prospective, randomised double-blind study on the anaesthetic effect of dexmedetomidine hydrochloride in brainstem tumour surgery

Context

Brainstem tumour surgery is difficult, and accidents can easily occur.

Objective

To explore the effect of dexmedetomidine hydrochloride on brainstem tumour surgery.

Design, setting and participants

A total of 60 patients with brainstem tumours successfully operated on by our hospital from March 2016 to March 2018 were selected as subjects.

Interventions

These patients were randomised into two groups: the research group (n = 30) and control group (n = 30). Patients in the control group were given propofol together with a placebo (0.9% sodium chloride solution) to maintain anaesthesia after general anaesthesia, while patients in the research group were supplemented with dexmedetomidine hydrochloride.

Main outcome measure

Awakening time, overall stability of various indicators in the operation and adverse reactions during the awakening period were observed.

Results

The results revealed that patients in the research group had a longer awakening time, higher mean stability rate, higher effective rate and less incidence of adverse reactions during the awakening period than the control group; the differences were all statistically significant (P < 0.05).

Conclusion

Dexmedetomidine hydrochloride has a good analgesic effect in intraoperative anaesthesia during brainstem tumour surgery, which significantly reduces the incidence of adverse reactions. Therefore, it can be used to assist anaesthesia during brainstem tumour operations and is worthy of clinical popularisation and application.

Comparison of bupivacaine plus intrathecal fentanyl and bupivacaine alone for spinal anesthesia with intravenous dexmedetomidine sedation: a randomized, double-blind, noninferiority trial

BACKGROUND AND OBJECTIVES

Fentanyl is widely used as an intrathecal adjuvant to local anesthetics to enhance the duration of spinal anesthesia. Recent evidence suggests that intravenous dexmedetomidine prolongs the duration of spinal anesthesia. This noninferiority study evaluated whether bupivacaine alone could provide a noninferior duration of block compared with bupivacaine and fentanyl when intravenous dexmedetomidine was administered intraoperatively.

METHODS

Fifty-six patients scheduled for total knee arthroplasty under spinal anesthesia were randomly allocated to receive either bupivacaine 13 mg with intrathecal fentanyl 20 µg (Group BF) or bupivacaine 13 mg (Group B). Both groups underwent intravenous dexmedetomidine sedation throughout the surgery (1 µg kg^-1 for 10 min, followed by 0.5 µg kg^-1 h^-1). The primary outcome was the time to two-segment regression of the sensory block. The noninferiority margin for the mean difference was predefined as -10 min. Secondary outcomes included postoperative pain scores, analgesics consumptions, and the incidences of pruritus, nausea, and vomiting.

RESULTS

There was no significant difference in the two-segment regression time of sensory block (Group B 109.1±25.0 min vs Group BF 104.3±25.9 min; p=0.484). The mean difference in the two-segment regression time between the 2 groups was 4.8 min (95 % CI -8.9 to 18.6), demonstrating the noninferiority of bupivacaine alone. Secondary outcomes showed no significant differences between the two groups.

CONCLUSIONS

The duration of spinal anesthesia with bupivacaine alone is noninferior to that of bupivacaine plus fentanyl in patients receiving intravenous dexmedetomidine intraoperatively. Our results suggest that intrathecal fentanyl may not be required when intravenous dexmedetomidine is administered.

TRIAL REGISTRATION NUMBER

NCT03105115.

Antinociception induced by a novel α2A adrenergic receptor agonist in rodents acute and chronic pain models

The mechanisms and antinociceptive effects of a novel α_2A adrenoceptor agonist, 3-(2-chloro-6-fluorobenzil)-imidazolinide-2,4-dione (PT-31) were investigated using animal models of acute and chronic pain. The effects of PT-31 on pain responses were examined using hot plate and formalin tests in mice and spinal nerve ligation (SNL)-induced hyperalgesia in rats. The effects of antagonists acting on α adrenoceptor were assessed to investigate the interaction of these pathways upon PT-31 induced antinociception. PT-31 effects on motor activity/skills and on hemodynamic parameters were also evaluated. PT-31 had dose-dependent antinociception effects on hot-plate and formalin-injection induced pain responses. Thermal hyperalgesia and mechanical allodynia were reduced following a 7 d treatment with PT-31 (1, 5, and 10mg/kg/d, p.o.), and those effects were attenuated by yohimbine (5mg/kg), atropine (2mg/kg), L-nitro arginine methyl ester (L-NAME; 30mg/kg), or naloxone (2mg/kg). In contrast to clonidine, PT-31 did not have locomotor or hemodynamic effects in rats. The present results suggest that PT-31 represents a candidate for pain treatment with advantages over clonidine, namely no locomotor or hemodynamic impairments.