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

Effects of dexmedetomidine, fentanyl and magnesium sulfate added to ropivacaine on sensory and motor blocks in lower abdominal surgery: a randomized clinical trial

This study aimed to compare the effects of intrathecal dexmedetomidine, fentanyl and magnesium sulfate added to ropivacaine on the onset and duration of sensory and motor blocks in lower abdominal surgery. This double-blind randomized clinical trial included 90 patients scheduled for lower abdominal surgery at Vali-Asr Hospital in Arak, Iran. The enrolled patients were randomly divided into three equal groups and then underwent spinal anesthesia. The first group received 10 μg of dexmedetomidine, the second group received 50 μg of fentanyl, and the third group received 200 mg of 20% magnesium sulfate intrathecally in addition to 15 mg of 0.5% ropivacaine. In the dexmedetomidine group, the mean arterial blood pressure was lower than the other two groups (P = 0.001). Moreover, the time to onset of sensory block (P = 0.001) and the mean duration of sensory block (P = 0.001) were shorter and longer, respectively, in the dexmedetomidine group than in the other two groups. In the dexmedetomidine group, the mean time to onset of motor block (P = 0.001) and the mean duration of motor block (P = 0.001) were lower and higher than in the other two groups, respectively. There was no significant difference in visual analog scale score, heart rate, administered opioid, and drug side effects among the three groups. Dexmedetomidine caused early sensory and motor blocks while prolonging the duration of sensory and motor blocks compared with the other two groups. In addition, dexmedetomidine reduced mean arterial blood pressure in patients. Based on the findings of this study, it is recommended that dexmedetomidine can be used in order to enhance the quality of sensory and motor block in patients.

Real-time evaluation of the independent analgesic efficacy of dexmedetomidine

BACKGROUND

Dexmedetomidine has analgesic properties, but the intraoperative analgesic effect of dexmedetomidine is often masked by the effects of other general anaesthetics. Therefore, the degree to which it reduces intraoperative pain intensity remains unclear. The objective of this double-blind, randomised controlled trial was to evaluate the independent intraoperative analgesic efficacy of dexmedetomidine in real-time.

METHODS

This single-centre study enrolled 181 patients who were hospitalised for below-knee orthopaedic surgeries between 19 January 2021 to 3 August 2021 were eligible for this is single-centre study. Peripheral neural block was performed on patients scheduled for below-knee orthopaedic surgeries. Patients were randomly assigned to the dexmedetomidine or midazolam group and were intravenously administered with 1.5 µg kg^-1 h^-1 dexmedetomidine or 50 µg kg^-1 h^-1 midazolam, respectively. The analgesic efficacy was evaluated using the real-time non-invasive nociception monitoring. The primary endpoint was the attainment rate of the nociception index target. The secondary endpoints included the occurrence of intraoperative hypoxemia, haemodynamic parameters, the consciousness index, electromyography and patient outcomes.

RESULTS

On Kaplan-Meier survival analysis, the defined nociception index target was attained in 95.45% and 40.91% of patients receiving dexmedetomidine and midazolam, respectively. Log-rank analysis revealed that the dexmedetomidine group attained the nociception index target significantly faster and the median attainment time of the nociception index target in the dexmedetomidine group was 15 min. Dexmedetomidine group was associated with a significantly lower incidence of hypoxemia. There was no significant difference in blood pressure between the dexmedetomidine and midazolam groups. Further, the dexmedetomidine group had a lower maximum visual analogue scale score and lower analgesic consumption postoperatively.

CONCLUSIONS

Dexmedetomidine has independent analgesia and systemically administered as an adjuvant agent has better analgesic efficacy than midazolam without severe side effects.

TRIAL REGISTRATION

clinicaltrial.gov Registry Identifier: NCT-04675372.Registered on 19/12 /2020.

Intrathecal Dexmedetomidine Combined With Ropivacaine in Cesarean Section: A Prospective Randomized Double-Blind Controlled Study

Objective

This study aimed to find the best dose of dexmedetomidine in spinal anesthesia for cesarean section.

Methods

120 American Society of Anesthesiologists (ASA) Class I and II parturients undergoing elective cesarean delivery under spinal anesthesia were randomly allocated into four groups treated with intrathecal ropivacaine (12 mg) alone (Group R) or in combination with dexmedetomidine 5 μg (Group RD1), 7.5 μg (Group RD2) and 10 μg (Group RD3). Characteristics of spinal anesthesia, hemodynamic changes, adverse effects, stress reactions and neonatal outcomes were recorded in the four groups.

Results

Patients in Group RD1, RD2, and RD3 had significantly longer sustained sensory and motor block time than patients in Group R. All four groups had comparable onset times of sensory and motor block. The time for the level of sensory block to lower to S1 was longer in Group RD1 (411.07 ± 106.66 min), Group RD2 (397.03 ± 125.39 min) and Group RD3 (468.63 ± 116.43 min) than in Group R (273.60 ± 88.34 min) (p < 0.001). The time to recover from motor block to a Bromage score of IV was longer in Group RD1 (353.60.07 ± 137.28 min), Group RD2 (350.57 ± 118.01 min) and Group RD3 (404.67 ± 112.83 min) than in Group R (232.70 ± 93.29) (p < 0.01). The incidence of chills was significantly lower in the Group RD1, RD2, and RD3 than in the Group R (p < 0.001). There was no significant difference in the incidence of adverse effects such as hypotension, bradycardia, nausea, vomiting, hypoxemia and pruritus in the four groups (p > 0.05). There was no statistically significant visceral traction response or fentanyl use in the four groups (p > 0.05). Phenylephrine dosing was significantly higher in Group RD2 and RD3 than in Group R (p < 0.05), and there was no significant difference in phenylephrine dosing between Group RD1 and Group R (p > 0.05). There were no statistical differences in postnatal Apgar scores (1 min, 5 min after birth) (p > 0.05). The postoperative concentrations of β-endorphin (β-EP), cortisol (Cor) and tumor necrosis factor-α (TNF-α) in the Group RD1, RD2, and RD3 were lower than that in Group R (p < 0.05).

Conclusion

Intrathecal 5μg of dexmedetomidine as an adjuvant to ropivacaine relieved intraoperative chills, did not increase intraoperative and postoperative adverse effects, did not increase the amount of intraoperative vasoconstrictor used, and reduced intraoperative stress reactions as well as prolonged the duration of maternal sensory and motor block, so this dose is appropriate for cesarean section.

Clinical Trial Registration

[www.chictr.org.cn/], identifier [ChiCTR2200056052].

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.

Effects of adding dexmedetomidine, fentanyl, and verapamil to 0.5% ropivacaine on onset and duration of sensory and motor block in forearm surgeries: a randomized controlled trial

This study was aimed to compare the onset and duration of axillary block with ropivacaine 0.5% plus either dexmedetomidine, fentanyl, or verapamil in forearm surgeries. This double-blind clinical trial enrolled three equal-sized block-randomized groups of patients (n = 105) scheduled for hand and forearm surgery at Arak, Iran in 2019, who received: (i) ropivacaine (40 mL/0.5%) + dexmedetomidine (1 μg/kg), (ii) ropivacaine (40 mL/0.5%) + fentanyl (1 μg/kg), and (iii) ropivacaine (40 mL/0.5%) + verapamil (2.5 mg), respectively. We recorded some vital signs such as mean arterial pressure, heart rate and oxygen saturation, onset of complete sensory and motor block, duration of the block, opioid use, as well as pain score at recovery and certain time points (2, 4, 6, 12, and 24 hours post-operation). Adding dexmedetomidine to ropivacaine (40 mL/0.5%) prolonged the duration of sensory (P = 0.001) and motor block (P = 0.001) in compared to adding fentanyl and verapamil and it also shortens the time to onset of sensory (P = 0.001) and motor block (P = 0.001). There is a significant difference between three groups in terms of visual analog scale mean and the lowest pain score was obtained in the dexmedetomidine group (P = 0.001), significant time trend (P = 0.001), as well as the time and groups interaction (P = 0.001). Dexmedetomidine was concluded to be associated with alleviated pain; reduced opioid use; short onset of sensory block; and prolonged duration of sensory and motor block. It hence is recommended to lengthen the duration of axillary block and to help relieve postoperative pain and ultimately to move to cut down the postoperative opioid use in forearm surgery. The study was approved by the Ethical Committee of Arak University of Medical Sciences (approval No. IR.ARAKMU. REC.1397.266), and registered on Iranian Registry of Clinical Trials (registration No. IRCT20141209020258N111) on May 9, 2019.