What dosing information is published for dexmedetomidine given via the epidural route as bolus and or infusion in the literature?

Comment by InpharmD Researcher

Published literature describing epidural dexmedetomidine demonstrates heterogeneous dosing with limited detail on administration methods. Systematic reviews report weight-based doses ranging from approximately 0.5 to 1.5 mcg/kg, while a meta-analysis specific to epidural use identified a range of 1 to 2 mcg/kg across trials, though bolus versus infusion strategies were not clearly defined. Individual studies provide more specific regimens, including single epidural boluses of 0.5 to 1 mcg/kg combined with local anesthetics, as well as continuous infusions such as 0.5 to 1 mcg/kg over 24 hours administered with ropivacaine. In obstetric populations, concentration-based epidural regimens are more commonly described, typically using dexmedetomidine 0.25 to 0.75 mcg/mL (most commonly 0.5 mcg/mL) with initial loading volumes (e.g., 10-13 mL), background infusion rates of 6-10 mL/h, and patient-controlled boluses of 5-8 mL. Dose-finding data suggest effective concentrations may be lower, while higher concentrations (e.g., 1 mcg/mL) may increase adverse effects.

Background

A 2014 meta-analysis of neuraxial dexmedetomidine identified 16 randomized, double-blind, placebo-controlled trials, of which four evaluated dexmedetomidine administered via the epidural route. Within the description of included-study characteristics, the reported epidural dexmedetomidine dose range was 1 to 2 mcg/kg; the main text does not provide additional study-level detail on exact epidural bolus versus infusion regimens, and the authors state that different dosages from the included studies were pooled without dose-stratified analysis. Within the epidural subgroup, the pooled analysis showed a reduction in postoperative pain intensity in 1 trial (n= 50; standardized mean difference [SMD] −1.23; 95% confidence interval [CI] −1.58 to −0.88) and a prolongation of postoperative analgesia duration in 1 trial (n= 36; weighted mean difference [WMD] 2.00 hours; 95% CI 0.65 to 3.35); epidural dexmedetomidine was also associated with no difference in onset of sensory block in 1 trial (n= 36), no difference in postoperative sedation scores in 1 trial (n= 50), and a prolonged duration of motor block in 1 trial (n= 36; WMD 90.00 minutes; 95% CI 36.47 to 143.53). Accordingly, based on these findings, published epidural dosing information reported in the literature is an epidural dexmedetomidine dose range of 1 to 2 mcg/kg across four trials, without further regimen-specific detail in the text regarding bolus and/or infusion administration. [1]

A 2021 meta-analysis of nine randomized controlled trials (RCTs) evaluating epidural dexmedetomidine for labor analgesia reported that the published epidural dosing regimens included six trials using dexmedetomidine 0.5 mcg/mL, one trial using dexmedetomidine 0.5 mcg/kg, one trial using dexmedetomidine 1 mcg/kg, and one dose-finding trial using dexmedetomidine 0.3, 0.4, 0.5, or 0.6 mcg/mL. In the studies using concentration-based epidural infusions with ropivacaine, reported regimens included an initial epidural dose of 10 or 13 mL, background infusion rates of 6 to 10 mL/h, patient-controlled epidural bolus doses of 5 to 8 mL, and lockout intervals of 15 to 30 minutes; one study specifically reported 13 mL ropivacaine with dexmedetomidine 0.3 to 0.6 mcg/mL as the administered epidural dose. One Egyptian trial reported an initial epidural bolus consisting of 12 mL of 0.25% bupivacaine plus dexmedetomidine 1 mcg/kg diluted in 5 mL saline, with a second dose administered when the visual analog scale score was ≥4. The review also stated that the actual dose of dexmedetomidine was not mentioned in all enrolled RCTs. [2]

A 2016 systematic review article assessed the efficacy and safety of dexmedetomidine as an adjuvant to other anesthetic medications for epidural procedures in various surgical procedures. Of 12 included studies (N= 660), the surgeries involved thoracic, abdominal, and lower limb surgery; cesarean section; hysterectomy; and nephrectomy. Across the included studies, dexmedetomidine doses ranged from 0.5 to 1.5 mcg/kg when used as an epidural or intrathecal adjuvant; administration (bolus vs. infusion) was generally unclear. Dexmedetomidine was compared to the same background epidural anesthesia without dexmedetomidine. The addition of dexmedetomidine significantly prolonged the duration of analgesia compared to control treatment (MD 3.50; 95% CI 1.86 to 5.13; p<0.0001). It also reduced the time to reach the sensory block (p= 0.002) and decreased the requirement for rescue analgesia (p<0.00001) and achieved significantly higher sedation score (p<0.0001). Heart rate was significantly lowered with intrathecal dexmedetomidine (p= 0.0009), but did not affect arterial pressure, systolic blood pressure, or diastolic blood pressure. The risks of hypotension, bradycardia, pruritus, dry mouth, nausea/vomiting and other side effects were not significantly different between dexmedetomidine and control groups, except the risk of shivering was significantly lower with dexmedetomidine. [3]

References: [1] Wu HH, Wang HT, Jin JJ, et al. Does dexmedetomidine as a neuraxial adjuvant facilitate better anesthesia and analgesia? A systematic review and meta-analysis. PLoS One. 2014;9(3):e93114. Published 2014 Mar 26. doi:10.1371/journal.pone.0093114
[2] Li N, Hu L, Li C, Pan X, Tang Y. Effect of Epidural Dexmedetomidine as an Adjuvant to Local Anesthetics for Labor Analgesia: A Meta-Analysis of Randomized Controlled Trials. Evid Based Complement Alternat Med. 2021;2021:4886970. Published 2021 Oct 27. doi:10.1155/2021/4886970
[3] Zhang X, Wang D, Shi M, Luo Y. Efficacy and Safety of Dexmedetomidine as an Adjuvant in Epidural Analgesia and Anesthesia: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Clin Drug Investig. 2017;37(4):343-354. doi:10.1007/s40261-016-0477-9
Literature Review

A search of the published medical literature revealed 10 studies investigating the researchable question:

What dosing information is published for dexmedetomidine given via the epidural route as bolus and or infusion in the literature?

Level of evidence

C - Multiple studies with limitations or conflicting results  Read more→


Please see Tables 1-10 for your response.

 

The Influence of Dexmedetomidine as an Adjuvant in Intrathecal Labor Analgesia: A Multicenter Study on Efficacy and Maternal Satisfaction

Design

Randomized double-blind trial (China)

N= 400

Objective

To examine the impact of dexmedetomidine (DEX) on the effectiveness of epidural analgesia and labor outcomes

Study Groups

0.1 mcg/mL DEX (n= 100)

0.2 mcg/mL DEX (n= 100)

0.3 mcg/mL DEX (n= 100)

0.3 mcg/mL Sufentanil (n= 100)

Inclusion Criteria

Patients with cephalic presentation in a full-term singleton pregnancy, admitted for vaginal delivery

Exclusion Criteria

N/A

Methods

Epidural block was used in all four groups for induction of labor anesthesia. Each group was also given ropivacaine 0.1%; additionally, patients were randomized to one of 4 treatment groups, 0.1, 0.2, or 0.3 mcg/mL DEX or 0.3 mcg/mL sufentanil. Following a 3 mL test dose, patients were administered 10 mL of treatment medication 2 to 3 times. After successful analgesia, patients were provided background infusion of 6 mL/h and patient-controlled epidural analgesia (PCEA) dose of 7 mL (lock-out time 20 minutes). 

Duration

N/A

Outcome Measures

Bromage score, PCEA, duration of labor, method of delivery, neonatal Apgar score, adverse reactions, maternal satisfaction

Baseline Characteristics

  

0.1 mcg/mL DEX (n= 100)

0.2 mcg/mL DEX (n= 100)

0.3 mcg/mL DEX (n= 100)

0.3 mcg/mL Sufentanil (n= 100)

  

Age, years

 27.4 26.7 27.2  27.9  

Height, cm

 158.7  157.6 163.7 162.1  

Weight, kg

 68.6  67.5 66.8  66.4  

Gestational age, weeks

 38.1  37.9 39.9  38.3  

Results

Endpoint

0.1 mcg/mL DEX (n= 100)

0.2 mcg/mL DEX (n= 100)

0.3 mcg/mL DEX (n= 100)

0.3 mcg/mL Sufentanil (n= 100)

p-Value

Bromage score ≥ 2

 10 (10%) 13 (13%) 39 (39%) 9 (9%) < 0.001

Number of additional PCEA doses

 29 (29%) 9 (9%) 6 (6%) 7 (7%) < 0.001

Maternal satisfaction

Highly satisfactory

Satisfactory

Unsatisfactory

 

67%

23%

10%

 

70%

22%

8%

 

26%

48%

26%

 

72%

21%

7%

 

-

-

-

Adverse reactions

Hypotension

Pruritus

Nausea and vomiting

Bradycardia

Abnormal changes in fetal heart rate

Urinary retention

 

0

7%

3%

1%

2%

18%

 

0

6%

2%

2%

3%

18%

 

0

5%

4%

11%

4%

19%

 

0

28%

6%

0%

3%

20%

 

-

0.000

0.364

0.000

0.854

0.954

No significant differences were reported between groups for cesarean section rate, duration of first and second stage of labor, or neonatal apgar score at 5 minutes. 

Adverse Events

 See Results section

Study Author Conclusions

The combination of 0.1% ropivacaine and 0.3 μg/mL DEX for epidural analgesia is not recommended because of the increased risks of motor block and bradycardia during labor, as well as the reduced satisfaction rates in primiparas when maintaining a VAS score of 0-3 throughout labor. The combination of 0.1% ropivacaine and 0.1 μg/mL DEX was less effective, necessitating higher analgesic doses to achieve satisfactory VAS scores. No significant differences were observed among the 4 combinations regarding the cesarean section rate, duration of the first and second stage of labor, and neonatal Apgar score at 5 minutes following birth. On the other hand, using 0.1% ropivacaine combined with 0.2 μg/mL DEX yielded favorable analgesic effects and higher levels of maternal satisfaction. Moreover, this combination resulted in a lower incidence of pruritus compared with using 0.1% ropivacaine combined with 0.3 μg/mL sufentanil. Consequently, epidural labor analgesia utilizing the combination of 0.1% ropivacaine and 0.2 μg/mL DEX holds promise for clinical application.

InpharmD Researcher Critique

This study included a relatively limited sample size, potentially hindering generalizability of findings. This study was conducted in China and was limited to a specific area, potentially hindering generalizability to a different country/region with varying clinical practices. 



References:
[1] [1] Lao C, Zhu M, Yang Y, et al. The Influence of Dexmedetomidine as an Adjuvant in Intrathecal Labor Analgesia: A Multicenter Study on Efficacy and Maternal Satisfaction [published online ahead of print, 2023 Aug 11]. J Clin Pharmacol. 2023;10.1002/jcph.2335. doi:10.1002/jcph.2335

 

Comparative Evaluation of Intrathecal Dexmedetomidine and Fentanyl as an Adjuvant for Combined Spinal-Epidural Analgesia for Labor

Design

Continuous, prospective, randomized, controlled, single-center trial

N= 120

Objective

To compare the safety and efficacy of fentanyl and dexmedetomidine as intrathecal adjuvants in labor analgesia

Study Groups

Dexmedetomidine (n= 59)

Fentanyl (n= 61)

Inclusion Criteria

Age 20 to 40 years old, body mass index (BMI) < 35 kg/m2, American Society of Anesthesiology (ASA) Classification Status I or II

Exclusion Criteria

Gestational age < 36 weeks, obstetric complications, second stage of labor or on oxytocin infusion, any condition contraindicating use of central neuraxial blockade

Methods

Patients were randomized to one of two treatment groups. Group A received bupivacaine 2.5 mg (0.5 mL diluted to 2 mL) + 20 μg dexmedetomidine in 1 mL saline intrathecally (total volume: 3 mL) while Group B received bupivacaine 2.5 mg (0.5 mL diluted to 2 mL) + fentanyl (15 μg) in 1 mL saline intrathecally (total volume: 3 mL). Patients could receive epidural top-up with 0.125% bupivacaine if needed. 

Duration

August 2021 to February 2022

Outcome Measures

Satisfactory analgesia (per visual analog scale [VAS] score ≤ 2), mode of delivery, quality of block, neonatal outcome

Baseline Characteristics

  

Dexmedetomidine (n= 59)

Fentanyl (n= 61)

  

Age, years

 25.9 26.7  

Weight, kg

 64.32  66.08   

Height, cm

 156.95  158.6   

Vitals

Heart rate, bpm

Systolic blood pressure, mmHg

Diastolic blood pressure, mmHg

Mean arterial pressure, mmHg

SpO2

 

111.15

117.40

75.20

84.26

99.35%

 

108.9

118.3

74.15

86.12

99.36%

  

VAS score

 8.92 8.76  

 

Results

Endpoint

Dexmedetomidine (n= 59)

Fentanyl (n= 61)

p-Value

Mode of delivery

Normal (n= 74)

Instrumental vaginal delivery (n= 14)

Cesarean delivery (n= 32)

 

34

8

17

 

40

6

15

 

0.046

0.062

0.0041

Quality of block

Onset time, seconds

Duration of analgesia (VAS score < 3), min

Degree of motor block (per Bromage Scale)

Top-up required in first 6 hours

 

61.26 ± 18.23

124.16 ± 26.23

5.12 ± 0.98

8.23 ± 2.43

 

92.54 ± 26.34

106.24 ± 18.91

5.88 ± 0.87

12.42 ± 4.48

 

0.0023

0.0081

0.039

0.002

Neonatal outcomes (among vaginally delivered babies)

APGAR at 1 min

APGAR at 5 min

pH

Heart rate at 1 min

Delayed cry

Intubation requirement

Survival at 6 weeks

 

6.36 ± 0.73

8.21 ± 0.25

7.28 ± 0.02

158.24 ± 12.43

12

1

34 (100%)

 

7.52 ± 0.58

8.71 ± 0.65

7.22 ± 0.31

169.87 ± 11.34

15

0

40 (100%)

 

0.038

0.06

0.07

0.034

0.051

N/A

N/A

Maternal side effects

Pruritus

Hypotension

Bradycardia

Nausea

Vomiting

 

0

5

4

1

0

 

21

3

2

3

1

 

0.0023

0.081

0.039

0.072

N/A

Sufficient analgesia was reported in 57 patients in the dexmedetomidine group vs. 54 patients in the fentanyl group. 

Adverse Events

 See Results

Study Author Conclusions

Walking epidural using intrathecal adjuvant is a safe and effective method for labor analgesia. Intensity and duration of block are higher with intrathecal dexmedetomidine. Normal vaginal delivery chances are higher with fentanyl. Fentanyl should be preferred over dexmedetomidine as an intrathecal adjuvant for labor analgesia.

InpharmD Researcher Critique

 This study is limited due to its limited sample size and single center design. Additionally, included patients were generally healthy, and results may vary when evaluating patients with comorbidities or other clinical scenarios. 



References:
[1] [1] Jain A, Mittal A, Sharma S, Deep A. Comparative Evaluation of Intrathecal Dexmedetomidine and Fentanyl as an Adjuvant for Combined Spinal-Epidural Analgesia for Labor. Anesth Essays Res. 2022;16(2):197-202. doi:10.4103/aer.aer_73_22

 

The optimal dose of dexmedetomidine as a 0.59% ropivacaine adjuvant for epidural anesthesia in great saphenous varicose vein surgery, based on hemodynamics and anesthesia efficacy: a randomized, controlled, double-blind clinical trial
Design

Randomized, controlled, double-blind clinical trial

N= 90
Objective To explore the optimal dose of dexmedetomidine as a 0.59% ropivacaine adjuvant for epidural anesthesia on perioperative hemodynamics and anesthesia efficacy in patients undergoing great saphenous varicose vein surgery
Study Groups

ED1 group (n= 28)

ED2 group (n= 30)

ED3 group (n= 27)
Inclusion Criteria American Society of Anesthesiologists (ASA) grades I or II; Patients scheduled for saphenectomy under epidural anesthesia; Age 18–65 years old; Height 140–180 cm and weight 40–80 kg; No contraindications to epidural anesthesia; Signed informed consent form
Exclusion Criteria Patients with hypertension (systolic blood pressure>160 mmHg) or hypotension (systolic blood pressure<90 mmHg); Cardiac insufficiency and bradycardia (heart rate<50 beats per minute); Allergic to dexmedetomidine injection and ropivacaine; Long-term use of analgesics, sedatives, depressant drugs, adrenergic receptor antagonists, and agonists; Liver and kidney insufficiency; Lower limb movement, hearing dysfunction, and mental system diseases
Methods

All patients received epidural anesthesia at the L2–L3 interspace in the left lateral position, using the loss-of-resistance technique with saline, and a catheter inserted 4–5 cm into the epidural space. After negative aspiration, a 3 mL test dose of 1.5% lidocaine was given. Patients were randomized into four groups: ED1 received 0.25 μg/kg dexmedetomidine, ED2 0.5 mcg/kg, ED3 0.75 mcg/kg, and the sufentanil control group received 0.3 mcg/mL sufentanil; all drugs were combined with 15 mL of 0.59% ropivacaine and administered epidurally at a rate of 0.5 mL/s to achieve a T10 sensory block. Routine monitoring included HR, ECG, NBP, and SPO₂, with oxygen at 2 L/min and lactated Ringer’s preload at 20 mL/kg/hr. Intraoperative hypotension (SBP < 90 mmHg) was treated with fluids and 6 mg ephedrine as needed; bradycardia (HR < 50 bpm) with 0.5 mg atropine. Pain with VAS > 3 was managed first with 3 mL 1% ropivacaine epidurally, then intramuscular tramadol 2 mg/kg up to 200 mg if needed. Postoperatively, ephedrine, atropine, tramadol, and ondansetron 4 mg for nausea/vomiting were administered as required with specified lockout intervals.
Duration June 2022 to November 2022
Outcome Measures

Primary: Systolic blood pressure (SBP) at various time points

Secondary: Diastolic blood pressure (DBP), heart rate (HR), and adverse reactions
Baseline Characteristics   ED1 group (n= 28) ED2 group (n= 30) ED3 group (n= 27)
Age, yr 55.7 ± 6.5 53.5 ± 7.3 53.5 ± 7.3
Gender, male/female 13/15 17/13 12/15
ASA, I/II 15/13 16/14 13/14
Body weight, kg 66.3 ± 8.7 64.8 ± 10.2 64.6 ± 8.4
Height, cm 162.0 ± 6.0 162.8 ± 8.3 163.6 ± 7.4
Operation time, min 111.1 ± 19.9 107.6 ± 30.5 110.2 ± 21.0
Infusion volume, mL 1139.3 ± 166.3 1100.0 ± 249.1 1159.3 ± 229.1
Blood loss, mL 89.8 ± 23.5 93.3 ± 25.1 86.1 ± 22.7
Results

In this study, hemodynamic and anesthetic outcomes varied by dexmedetomidine dose. Compared with the ED1 group (0.25 mcg/kg), the ED2 group (0.5 mcg/kg) had significantly lower systolic blood pressure at T1–T3 (T1: 6.52–21.93 mmHg, p< 0.001; T2: 2.88–18.21 mmHg, p= 0.004; T3: 0.49–18.17 mmHg, p= 0.035) and lower diastolic blood pressure at T1–T2 (T1: 4.55–14.36 mmHg, p < 0.001; T2: 0.37–12.17 mmHg, p= 0.033). Compared with ED2, the ED3 group (0.75 mcg/kg) had higher systolic BP at T1–T2 (T1: 5.90–21.46 mmHg, p< 0.001; T2: 2.07–17.55 mmHg, p= 0.008) and higher diastolic BP at T1–T3 (T1: 2.91–12.81 mmHg, p= 0.001; T2: 1.32–13.23 mmHg, p= 0.011; T3: 0.14–11.52 mmHg, p= 0.043). Heart rate in ED3 was significantly lower than ED2 at T1–T4 (T1: 2.25–15.72 bpm, p= 0.005; T2: 2.35–13.82 bpm, p= 0.003; T3: 0.50–9.79 bpm, p= 0.025; T4: 1.46–10.36 bpm, p= 0.005). Myocardial oxygen consumption decreased from baseline in all groups (p < 0.05), with no significant between-group differences.
Adverse Events The incidence of sinus bradycardia in ED2 and ED3 groups was observably elevated compared to the ED1 group (21.4% vs. 46.7% & 51.9%, p= 0.023). One patient in the ED3 group experienced difficulty urinating. Remaining adverse reactions were mild in all three groups.
Study Author Conclusions A measure of 0.5 mcg/kg dexmedetomidine is the optimal dose as a 0.59% ropivacaine adjuvant for epidural anesthesia in patients undergoing great saphenous varicose vein surgery.
Critique The study was well-designed as a randomized, controlled, double-blind trial, providing robust data on the optimal dose of dexmedetomidine. However, the fixed concentration of ropivacaine may not reflect real-world variability, and the study did not measure the concentration of dexmedetomidine in cerebrospinal fluid or blood, which could provide further insights into its pharmacodynamics and pharmacokinetics. Additionally, the study did not explore the effects in major surgeries with large hemodynamic fluctuations, which could limit the generalizability of the findings.
References:
[1] [1] Zeng S, Li X, Xu H, Ye Q, Li Z, Wang F. The optimal dose of dexmedetomidine as a 0.59% ropivacaine adjuvant for epidural anesthesia in great saphenous varicose vein surgery, based on hemodynamics and anesthesia efficacy: a randomized, controlled, double-blind clinical trial. Front Med (Lausanne). 2024;11:1426512. Published 2024 Jul 24. doi:10.3389/fmed.2024.1426512

Optimal Dose of Epidural Dexmedetomidine Added to Ropivacaine for Epidural Labor Analgesia: A Pilot Study
Design

Prospective, single-blinded study

N= 100
Objective To investigate the effect of adding different doses of epidural dexmedetomidine to ropivacaine during epidural labor analgesia
Study Groups

Group A (0.25 μg/ml dexmedetomidine, n= 25)

Group B (0.5 μg/ml dexmedetomidine, n= 25)

Group C (0.75 μg/ml dexmedetomidine, n= 25)

Group D (1 μg/ml dexmedetomidine, n= 25)
Inclusion Criteria Parturient women with gestational weeks ≥37, ASA I or II
Exclusion Criteria ASA grades III–V, contraindication to epidural anesthesia, undergoing caesarean section
Methods Randomized assignment to four groups receiving 0.25, 0.5, 0.75, and 1 μg/ml of dexmedetomidine plus 0.1% ropivacaine. Epidural analgesia performed at L2-3 interspace. Monitoring of vitals, fetal heart rate, Apgar scores, and umbilical artery pH. Side effects recorded. Analgesia onset and labor stages studied. Visual analogue scale (VAS) used for pain assessment.
Duration Not specified
Outcome Measures Analgesic efficacy, side effects, neonatal Apgar score
Baseline Characteristics   0.25 μg/ml (n = 25) 0.5 μg/ml (n = 25) 0.75 μg/ml (n = 25) 1 μg/ml (n = 25) p-value
Maternal age, years 28.4 ± 3.5 29.1 ± 4.2 27.8 ± 3.8 27.5 ± 2.9 0.521
Weight, kg 71.3 ± 5.7 74.3 ± 6.8 69.3 ± 4.5 72.6 ± 7.1 0.258
Height, cm 159.3 ± 3.4 161.5 ± 4.5 158.7 ± 3.6 162.2 ± 4.3 0.586
Gestational age, week 38.7 ± 1.8 39.3 ± 2.2 38.2 ± 1.7 39.1 ± 2.1 0.321
Results   0.25 μg/ml (n = 25) 0.5 μg/ml (n = 25) 0.75 μg/ml (n = 25) 1 μg/ml (n = 25) p-value
Onset time of analgesia, min 15.8 ± 3.6 15.4 ± 4.1 15.0 ± 3.8 14.8 ± 3.4 0.723
Time of the first stage of labor, min 358.7 ± 86.5 372.4 ± 95.8 381.7 ± 89.4 388.2 ± 85.2 0.272
Time of the second stage of labor, min 39.8 ± 12.6 41.2 ± 8.6 40.5 ± 9.8 42.4 ± 11.5 0.681
Blood loss, ml 205.6 ± 19.5 198.6 ± 24.8 194.5 ± 26.7 192.2 ± 21.4 0.728
Neonatal Apgar score at 1st min, score 9.0 ± 0.62 8.8 ± 0.58 8.9 ± 0.56 8.7 ± 0.47 0.686
Neonatal Apgar score at 5th min, score 9.7 ± 0.81 9.6 ± 0.72 9.5 ± 0.68 9.6 ± 0.75 0.564
Adverse Events Higher incidence of motor block in Group D (1 μg/ml dexmedetomidine). Side effects in Group D were significantly higher than in the other three groups (p< 0.05). No significant differences in systolic blood pressure and heart rate between groups. No significant difference in SpO2 and respiratory depression between groups.
Study Author Conclusions The optimal concentration of dexmedetomidine for epidural labor analgesia when combined with 0.1% ropivacaine is 0.5 μg/ml, providing effective analgesia with minimal side effects.
Critique The study provides valuable insights into the optimal dosing of dexmedetomidine for epidural labor analgesia. However, the single-blinded design and limited sample size may affect the generalizability of the results. Further studies with larger sample sizes and double-blinded designs are needed to confirm these findings.
References:
[1] [1] Wangping Z, Ming R. Optimal Dose of Epidural Dexmedetomidine Added to Ropivacaine for Epidural Labor Analgesia: A Pilot Study. Evid Based Complement Alternat Med. 2017;2017:7924148. doi:10.1155/2017/7924148

Determination of the Dose-Response Relationship of Epidural Dexmedetomidine Combined with Ropivacaine for Labor Analgesia
Design

Prospective, randomized, dose-finding study

N= 120
Objective

To determine the dose-response relationship of epidural dexmedetomidine (combined with ropivacaine) for labor analgesia
Study Groups

Dexmedetomidine 0 μg/mL (n= 20)

Dexmedetomidine 0.1 μg/mL (n= 20)

Dexmedetomidine 0.2 μg/mL (n= 20)

Dexmedetomidine 0.3 μg/mL (n= 20)

Dexmedetomidine 0.4 μg/mL (n= 20)

Dexmedetomidine 0.5 μg/mL (n= 20)
Inclusion Criteria

Full-term laboring parturients requesting epidural labor analgesia, ASA physical status I or II, age 18 to 40 years, height 150 cm or greater, weight 100 kg or less, baseline NRS pain scores > 3
Exclusion Criteria

Allergy to amide-type local anesthetics or dexmedetomidine, bradycardia, multiple gestation pregnancies, pregnancy-induced hypertension or preeclampsia, known fetal abnormality, lack of informed consent
Methods

Parturients were randomly assigned to receive 0, 0.1, 0.2, 0.3, 0.4, or 0.5 μg/mL dexmedetomidine combined with 0.075% ropivacaine epidurally. An effective dose was defined as NRS pain score ≤3 at 30-minutes of epidural drug injection. Probit regression was used to determine the dose-response relationship.
Duration

July 5, 2020 to September 22, 2021
Outcome Measures

Primary: Effective rates of labor analgesia for different doses of dexmedetomidine with 0.075% ropivacaine at 30-minutes

Secondary: Sensory block level, Bromage score, total dosage of analgesics, cesarean delivery rate, fetal birth weight, Apgar scores, adverse effects
Baseline Characteristics  

Dexmedetomidine 0 μg/mL (n= 20)

 Dexmedetomidine 0.1 μg/mL (n= 20) Dexmedetomidine 0.2 μg/mL (n= 20) Dexmedetomidine 0.3 μg/mL (n= 20) Dexmedetomidine 0.4 μg/mL (n= 20) Dexmedetomidine 0.5 μg/mL (n= 20) p-value

Age, years

 27.9 ± 2.7 28.3 ± 4.1 27.9 ± 3.2 27.9 ± 2.3 28.0 ± 3.5 28.3 ± 3.5 0.996

Height, cm

 161.7 ± 4.4 160.5 ± 4.1 160.6 ± 5.3 161.7 ± 4.2 159.0 ± 3.8 161.1 ± 4.2 0.401

Weight, kg

 70.3 ± 5.6 66.6 ± 10.7 69.4 ± 11.7 70.4 ± 7.7 67.2 ± 6.1 67.9 ± 7.6 0.607

Parity

 0 (0–1) 0 (0–1) 0 (0–0) 0 (0–1) 0 (0–1) 0 (0–1) 0.986

Nulliparous

 14 (70%) 14 (70%) 15 (75%) 14 (70%) 13 (65%) 13 (65%) 0.985

Gestational age, weeks

 39.2 ± 1.1 38.9 ± 1.0 38.9 ± 1.0 39.3 ± 0.8 38.9 ± 0.7 39.3 ± 0.9 0.423

Cervical dilation, cm

 2.8 ± 0.7 3.2 ± 0.6 2.8 ± 0.6 3.1 ± 0.4 3.1 ± 0.6 3.0 ± 0.6 0.157
Results  

Dexmedetomidine 0 μg/mL (n= 20)

 Dexmedetomidine 0.1 μg/mL (n= 20) Dexmedetomidine 0.2 μg/mL (n= 20) Dexmedetomidine 0.3 μg/mL (n= 20) Dexmedetomidine 0.4 μg/mL (n= 20) Dexmedetomidine 0.5 μg/mL (n= 20) p-value

Patients with inadequate analgesia

 12 11 6 2 0 0

Success rate

 8 (40%) 9 (45%) 14 (70%) 18 (90%) 20 (100%) 20 (100%)

Sensory block level

 T8 (8–9) T9 (7–10) T8 (7–10) T8 (7–8) T8 (6–9) T8 (7–8) 0.075

Onset of analgesia, minutes

 14.1 ± 5.2 14.2 ± 2.5 15.4 ± 5.6 15.2 ± 3.5 16.7 ± 6.3 12.7 ± 4.4 0.186

Duration of first stage, minutes

 405.1 ± 147.9 435.4 ± 280.3 422.5 ± 204.0 419.4 ± 200.8 421.6 ± 195.1 622.3 ± 333.0 < 0.05

Duration of second stage, minutes

 58.6 ± 48.4 47.9 ± 41.1 57.7 ± 35.6 41.9 ± 31.9 46.9 ± 35.7 62.7 ± 42.5 0.535

Total dosage of analgesics, mL

 20.7 ± 10.7 23.5 ± 15.4 27.2 ± 19.1 25.8 ± 14.5 24.4 ± 14.9 32.0 ± 21.0 0.384

Cesarean delivery rate

 0 (0%) 3 (15%) 0 (0%) 1 (5%) 0 (0%) 1 (5%) 0.131

Fetal birth weight, g

 3400.0 ± 282.0 3447.1 ± 403.3 3302.5 ± 396.2 3451.8 ± 329.9 3366.3 ± 371.0 3400.0 ± 308.6 0.865

Apgar score, 1 min

 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 1.000

Apgar score, 5 min

 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 10 (10–10) 1.000
Adverse Events

No statistical differences were noted for adverse effects including hypotension, nausea and vomiting, pruritus, bradycardia, maternal fever, respiratory depression, and excessive sedation.
Study Author Conclusions

The ED50 and ED95 values of dexmedetomidine for epidural labor analgesia were 0.085 and 0.357 μg/mL. Dexmedetomidine is a suitable adjuvant for epidural labor analgesia.
Critique

This was a well-conducted randomized dose-finding study with clearly described epidural loading and maintenance dosing, making it especially useful for your literature question on epidural bolus plus infusion concentrations. Its main limitation is that efficacy was defined only at 30 minutes and the findings apply specifically to dexmedetomidine combined with 0.075% ropivacaine in laboring parturients, so generalizability to other epidural regimens, populations, or non-obstetric uses is limited; additionally, the 0.5 μg/mL concentration may be less attractive clinically because it prolonged first-stage labor despite 100% short-term analgesic success.
References:
[1] [1] Ni JX, Feng JL, Yao SJ, et al. Determination of the Dose-Response Relationship of Epidural Dexmedetomidine Combined with Ropivacaine for Labor Analgesia. Drug Des Devel Ther. 2022;16:609-618. Published 2022 Mar 6. doi:10.2147/DDDT.S346842

 

Intrathecal dexmedetomidine can decrease the 95% effective dose of bupivacaine in spinal anesthesia for cesarean section

Design

Prospective, double-blind, randomized study (China)

N= 90

Objective

 To verify our hypothesis that Dex can enhance the efficiency of intrathecal bupivacaine with an improved up–down allocation method

Study Groups

Dexmedetomidine (n= 45)

Control (n= 45)

Inclusion Criteria

 Partiurients with American Society of Anesthesiology (ASA) physical class I or II, undergoing elective cesarean section

Exclusion Criteria

 Body mass index (BMI) > 35 kg/m2, gestational age < 37 weeks, diabetes or gestational diabetes, hypertension or pre-eclampsia

Methods

Patients were randomized to receive either bupivacaine plus 5 mcg dexamethasone or bupivacaine plus matching placebo saline. Subsequent doses of bupivacaine were administered based on the improved up-down allocation method:

Up-down allocation method: involved determining the subsequent dose of spinal bupivacaine based on the probability of the current dose. If the probability exceeded 95%, the next dose would decrease by 1 mg, while if the probability was less than 95%, the next dose would increase by 1 mg. If the probability remained at 95%, the dose would remain unchanged.

The effectiveness of the dose was evaluated based on achieving a sensory block level within a specific timeframe, and ineffective doses were supplemented with lidocaine via an epidural catheter until the desired sensory block level was reached.

Duration

 N/A

Outcome Measures

Primary: 95% effective dose (dose of drug that produces a desired effect in 95% of individuals or patients)

Secondary: characteristics of spinal anesthesia, duration of spinal analgesia, side effects

Baseline Characteristics

  

Dexmedetomidine (n= 45)

Control (n= 45)

  

Age, years

 27 26  

Height, cm

 162 161  

Weight, kg

 71 72  

Gestational age, week

 39 39  

Duration of surgery, min

 43 45  

Results

Endpoint

Dexmedetomidine (n= 45)

Control (n= 45)

p-Value

95% effective dose, mg (95% confidence interval [CI])

7.4 (5.6 to 12.4)

11.0 (4.4 to 56.8)

--

Sensory block

Highest level of block

Onset time of sensory block, min

Time to highest level, min

Duration, min

 

T5 (T3-T6)

4.7 ± 1.1

15.6 ± 4.5

120.5 ± 37.0

 

T5 (T3-T6)

4.5 ± 1.3

14.8 ± 4.2

70.5 ± 34.5

 

> 0.05

> 0.05

> 0.05

< 0.05

Motor block onset time, min

4.1 ± 2.0

4.3 ± 1.9

> 0.05

Duration of analgesia, min

230.5 ± 40.5

145.1 ± 28.5

< 0.001

Consumption of sufentanil, mcg

56.3 ± 9.4

65.9 ± 10.7

< 0.05

Patient satisfaction

Excellent

Good

 

24 (63%)

14 (37%)

 

21 (55%)

17 (45%)

 

> 0.05

> 0.05

Adverse events

Hypotension

Nausea/vomiting

Respiratory depression

Shivering

Post-dural puncture headache

Pruritus

Umbilical artery pH

 

7 (16%)

6 (13%)

0

8 (18%)

0

0

7.30 ± 0.05

 

14 (31%)

9 (20%)

0

12 (27%)

0

0

7.29 ± 0.04

 

0.08

> 0.05

> 0.05

> 0.05

> 0.05

> 0.05

> 0.05

Adverse Events

 See above

Study Author Conclusions

Intrathecal 5 mcg dexmedetomidine enhances the efficacy of spinal bupivacaine by 24% in patients undergoing cesarean section with spinal anesthesia. No additional side effect was observed by adding spinal dexmedetomidine

InpharmD Researcher Critique

 The 95% effective dose of dexmedetomidine presents a wide confidence interval which presents uncertainty of the study results.



References:
[1] [1] Liu L, Qian J, Shen B, Xiao F, Shen H. Intrathecal dexmedetomidine can decrease the 95% effective dose of bupivacaine in spinal anesthesia for cesarean section: A prospective, double-blinded, randomized study. Medicine (Baltimore). 2019;98(9):e14666. doi:10.1097/MD.0000000000014666

 

A comparison of Intrathecal Dexmedetomidine Verses Intrathecal Fentanyl with Epidual Bupivacaine for combined Spinal Epidural Labor Analgesia

Design

Randomized observational study

N= 112

Objective

 To compare the duration and quality of analgesia, maternal and neonatal outcomes after combined spinal epidural (CSE) labor analgesia with intrathecal dexmedetomidine and intrathecal fentanyl followed by epidural bupivacaine

Study Groups

Dexmedetomidine 10 μg (n= 58)

Fentanyl 20 μg (n= 54)

Inclusion Criteria

Age 18 to 35 years, American Society of Anesthesiologists (ASA) class I and II, uncomplicated pregnancy scheduled for normal vaginal delivery, vertex presentation not in fetal distress, singleton fetus

Exclusion Criteria

Local infection, altered coagulation profile, maternal valvular heart disease, previous caesarean section, preexisting neurological disease, severe deformity of spine

Methods

All patients included in the study received 15 mL/kg Ringer lactate solution intravenously. Baseline hemodynamic parameters were noted. Intrathecal analgesia was administered when the patient was in active labor, having pain with uterine contractions and cervical dilatation of 3 cm to 4 cm as confirmed by the obstetrician. The baseline visual analog score (VAS) for pain recorded was between 6 and 9 for all the patients in which 0 represented no pain and 10 represented worst possible pain. After intrathecal injection of experimental drug. An epidural catheter was inserted into the epidural space using the CSE set and secured for future administration of 0.125% bupivacaine as and when required. The top-ups with 10 mL of 0.125% bupivacaine were initiated when the VAS for pain was recorded above 3. This was repeated as needed, when the VAS for pain was recorded above 3 until delivery.  To assess depth of analgesia lowest VAS score achieved during contractions after administration of intrathecal drug were compared in both groups.

Duration

The study was carried out over a period of a year. Maternal data was analyzed after 50 cases were completed in each group. The study continued for 6 weeks thereafter to ensure follow-up of at least 50 newborns at 6 weeks, by which time 112 cases were totally conducted. 

Outcome Measures

Onset of analgesia, time to reach maximum analgesia, duration of analgesia, maternal side-effects, and neonatal outcomes

Baseline Characteristics

  

Dexmedetomidine (n= 50)

Fentanyl (n= 50)

  

Age, years

 24.10 (± 3.09) 24.44 (± 3.09)  

Weight, kg

 64.14 (± 5.76) 64.38 (± 6.55)   

Primipara

 38 (76%) 40 (80%)  

Multipara

 12 (24%) 10 (20%)  

ASA

Grade I

Grade II

 

37 (74%)

12 (26%)

 

39 (78%)

11 (22%)

  

Baseline VAS

 >6 >6  

ASA: American Society of Anesthesiologists; VAS: Visual analog score

Results

Endpoint

Dexmedetomidine (n=50)

Fentanyl (n=50)

p-value

Time to onset

 50.4 ± 16.81 71.7 ± 27.66 <0.001 

Time to maximum analgesia

 246.6 ± 77.45  160.8 ± 56.45 <0.001 

Duration of analgesia

 160.54 ± 52.4 124.1 ± 46.93 <0.001

Normal delivery

 30 (51.7%) 32 (59.3%) NS

Maternal adverse events

Pruritus

Hypotension

Bradycardia

Paresthesia

 

0

2 (4%)

1 (2%)

0

 

37 (74%)

1 (2%)

1 (2%)

1 (2%)

 

< 0.001

NS

NS

NS

No significant differences were observed between groups for any neonatal outcomes, including need for resuscitation, delayed cry, breast feeding initiation, nonvigorous Neurologic and Adaptive Capacity Score, and exclusivity at 6 weeks. 

NS: not significant

Adverse Events

See Results

Study Author Conclusions

10 μg dexmedetomidine is an attractive alternative to 20 μg fentanyl as an intrathecal agent for CSE labor analgesia. It provides acceptable quality of labor analgesia with increased duration of analgesia compared to fentanyl. It maintains hemodynamic stability with no adverse effects on mother and the newborn.

InpharmD Researcher Critique

This study utilized a previously studied experimental dose of dexmedetomidine that has been proven to achieve satisfactory analgesia for labor. Despite its randomized design, the study still incorporated a limited sample size.

Overall, VAS for pain recorded at maximal analgesia was significantly lesser in the fentanyl group compared to dexmedetomidine group, denoting a significantly deeper level of analgesia with fentanyl compared to dexmedetomidine. Additionally, the significantly longer duration of analgesia resulting from dexmedetomidine decreases the need for increased top-ups.   



References:
[1] [1] Dilesh P, Eapen S, Kiran S, Chopra V. A comparison of intrathecal dexmedetomidine verses intrathecal fentanyl with epidural bupivacaine for combined spinal epidural labor analgesia. J Obstet Anaesth Crit Care. 2014;4(2):69. doi:10.4103/2249-4472.143875

Comparison of epidural dexmedetomidine to fentanyl in reducing ropivacaine dose in Programmed Intermittent Epidural Bolus plus Patient Controlled Epidural Analgesia during labor: A randomized, double-blind, controlled study
Design

Randomized, double-blind, controlled study

N= 188
Objective To evaluate the efficacy of epidural dexmedetomidine at doses of 0.3, 0.4, or 0.5 µg/ml compared to fentanyl at 2 µg/ml as adjuvants to epidural 0.125% ropivacaine in reducing the mean hourly dose requirement of ropivacaine during labor analgesia
Study Groups

Fentanyl 2 µg/ml (n= 40)

Dexmedetomidine 0.3 µg/ml (n= 39)

Dexmedetomidine 0.4 µg/ml (n= 45)

Dexmedetomidine 0.5 µg/ml (n= 41)
Inclusion Criteria Nulliparous parturients with healthy singleton pregnancies, gestational age ≥37 weeks, ASA Physical Status II, spontaneous onset of labor, latent phase of labor with cervical dilation of 2–5 cm, and requiring labor epidural analgesia
Exclusion Criteria Preeclampsia or hypertension, preexisting or gestational diabetes, BMI > 35 kg/m2, contraindications to local anesthetics, dexmedetomidine, and fentanyl
Methods Patients were randomized into four groups to receive either 2 µg/ml fentanyl or 0.3, 0.4, or 0.5 µg/ml dexmedetomidine as adjuvants to epidural 0.125% ropivacaine. Data were collected and analyzed using statistical software. 
Duration Data collection occurred from February 3, 2021, until the completion of the study
Outcome Measures

Mean hourly amount of ropivacaine administered, side effects, patient satisfaction
Baseline Characteristics   Fentanyl 2 µg/ml (n = 40) Dexmedetomidine 0.3 µg/ml (n = 39) Dexmedetomidine 0.4 µg/ml (n = 45) Dexmedetomidine 0.5 µg/ml (n = 41)
Age, years 27.6 ± 3.7 28.3 ± 3.7 27.4 ± 3.4 28.8 ± 3.5
BMI, kg/m2 26.1 ± 3.0 27.5 ± 2.4 27.0 ± 3.2 27.2 ± 2.4
Gestational age, weeks 39.3 ± 1.1 39.3 ± 1.0 39.1 ± 1.0 39.5 ± 2.0
Cervical dilation at epidural placement, cm 2.1 ± 0.3 2.2 ± 0.4 2.2 ± 0.4 2.1 ± 0.4
Results   Fentanyl 2 µg/ml Dexmedetomidine 0.3 µg/ml Dexmedetomidine 0.4 µg/ml Dexmedetomidine 0.5 µg/ml p-value
Mean hourly ropivacaine consumption, ml/h 16.2 ± 3.3 14.0 ± 3.1 13.1 ± 3.7 12.1 ± 2.5 <0.0001
Frequency of patient-controlled epidural analgesia (PCEA) boluses 3 (1-3) 0 (0-2) 0.5 (0-2) 0 (0-1) <0.001
Incidence of pruritus 17.5% 0.0 0.0 0.0 <0.001
VAS scores were similar across groups over time (p > 0.05; data presented in figure), with pain relief observed 20 minutes after epidural injection in all groups. Although satisfaction differed significantly among groups (p = 0.002), mean scores exceeded 4.0 (scale 1–5). Mean satisfaction was 4.2 in the fentanyl group and 4.8, 4.7, and 4.8 in the 0.3, 0.4, and 0.5 mg/mL dexmedetomidine groups, respectively.
Adverse Events Pruritus occurred in 17.5% of patients receiving fentanyl and in none of the dexmedetomidine groups (p < 0.001). Bromage scores differed among groups (p = 0.007), with the highest incidence in the 0.5 mg/mL dexmedetomidine group (3 patients with score 2, 6 with score 1), followed by the 0.4 mg/mL group (3 with score 1), the 0.3 mg/mL group (1 with score 1), and the fentanyl group (2 with score 1). Rates of nausea/vomiting, shivering, severe sedation, and respiratory depression were similar across groups.
Study Author Conclusions Epidural dexmedetomidine (0.3 and 0.4 µg/ml) is superior to standard dose epidural fentanyl in reducing the mean hourly amount of ropivacaine administered and minimizing opioid-related side effects. Further large and multicenter studies are necessary to confirm the benefits of dexmedetomidine as an alternative to opioids for routine use in labor analgesia. 
Critique The study was well-designed with a randomized, double-blind approach, providing robust data on the efficacy of dexmedetomidine as an adjuvant in labor analgesia. However, the sample size may not have been sufficient to detect differences in secondary outcomes, and the study did not clarify the dose-response relationship of dexmedetomidine on epidural ropivacaine. Additionally, dexmedetomidine remains an investigational drug for epidural use, necessitating further research to confirm its safety and efficacy. 
References:
[1] [1] Pang RY, Shen YH, Jin XQ, et al. Comparison of epidural dexmedetomidine to fentanyl in reducing ropivacaine dose in Programmed Intermittent Epidural Bolus plus Patient Controlled Epidural Analgesia during labor: A randomized, double-blind, controlled study. Front Med (Lausanne). 2022;9:935643. Published 2022 Oct 17. doi:10.3389/fmed.2022.935643

Comparison of Two Different Doses of Dexmedetomidine for Continuous Epidural Analgesia for Lower Limb Surgeries: A Randomized Double‑Blind Study
Design

Randomized double-blind study

N= 72
Objective

To compare the analgesic efficacy and safety of two different doses of dexmedetomidine in continuous epidural for postoperative analgesia
Study Groups

Group I (n= 36): 0.1% ropivacaine + 0.5 µg/kg/24 h dexmedetomidine

Group II (n= 36): 0.1% ropivacaine + 1 µg/kg/24 h dexmedetomidine
Inclusion Criteria

Patients aged 18-60 years, ASA I and II, undergoing elective lower limb orthopedic surgeries, willing to participate
Exclusion Criteria

Known cardiac illness, hypertension, coagulation abnormalities, extremes of BMI, pregnant/lactating patients
Methods

Patients were randomly allocated into two groups. Group I received 0.1% ropivacaine + 0.5 µg/kg/24 h dexmedetomidine, and Group II received 0.1% ropivacaine + 1 µg/kg/24 h dexmedetomidine. Both groups received epidural infusion at 5 ml/h over 48 hours postoperatively. Pain scores, demand for rescue analgesics, hemodynamic parameters, and sedation scores were compared. Statistical analysis was done using independent t-test and Chi-square test.
Duration

18 months
Outcome Measures

Primary: Analgesic efficacy in terms of pain scores

Secondary: Safety profile measured by sedation score and hemodynamic parameters, total number of rescue analgesics required
Baseline Characteristics  

Group I Mean (n= 36)

 Group II Mean (n= 36)
Age, years 37.39 ± 12.71

39.78 ± 10.61
Weight, kg

55.86 ± 9.47

 60.89 + 12.99
Female

18

 17

Type of surgeries

PFN

Hemiarthroplasty

Nailing for both bone fracture (Leg)

DHS fixation

 

16 (45.5%)

6 (16.5%)

10 (27%)

4 (11%)

 

18 (50%)

5 (14%)

11 (30.5%)

2 (5.5%)

Abbreviations: PFN, proximal femoral nailing; DHS, dynamic hip screw
Results  

Group I Mean (n= 36)

 Group II Mean (n= 36) p-value

NPRS at 4th Hour

4.42 ± 0.60

 2.36 ± 0.49 0.001
NPRS at 8th Hour

4.56 ± 0.65

 2.33 ± 0.48 0.000
NPRS at 12th Hour

4.22 ± 0.54

 2.19 ± 0.40 0.001
NPRS at 16th Hour

4.14 ± 0.49

 2.39 ± 0.49 0.003
NPRS at 20th hour

4.06 ± 0.33

 2.39 ± 0.49 0.001
NPRS at 24th Hour

4.36 ± 0.54

 2.31 ± 0.47 0.001
NPRS at 32nd Hour

4.28 ± 0.70

 2.31 ± 0.47 0.001
NPRS at 40th Hour

4.25 ± 0.60

 2.33 ± 0.53 0.00
NPRS at 48th Hour

4.06 ± 0.23

 2.44 ± 0.56 0.00

Abbreviations: NPRS, numeric pain rating scale
Adverse Events

Incidence of hypotension was higher in Group II. Bradycardia was seen in two patients in Group II and none in Group I.
Study Author Conclusions

We conclude that dexmedetomidine in a dose of 1 μg/kg/24 h with 5 ml/h of 0.1% ropivacaine through epidural infusion provides better analgesia with lower pain scores and less demand for rescue analgesic than 0.5 μg/kg/24 h with acceptable hemodynamic variations.
Critique

The study effectively compares two doses of dexmedetomidine for epidural analgesia, showing clear differences in analgesic efficacy and hemodynamic stability. However, the study could have benefited from including a mid-range dose group for a more comprehensive understanding of dose-dependent effects. Additionally, patient satisfaction scores were not monitored, which could have provided further insights into the patient experience. The study's findings are limited to the specific population and settings, which may affect generalizability.
References:
[1] [1] Kurhekar P, Sheba SB, Meenakshisundaram S, Sethuraman RM, Parlikar N. Comparison of two different doses of dexmedetomidine for continuous epidural analgesia for lower limb surgeries: A randomized double-blind study. J Anaesthesiol Clin Pharmacol. 2024;40(3):451-456. doi:10.4103/joacp.joacp_88_23

 

Comparison of the Analgesic Efficacy of a Single Dose of Epidural Dexmedetomidine versus Fentanyl as an Adjuvant to Bupivacaine in Abdominal Surgery
Design

Prospective, randomized, controlled, double-blind trial

N= 46
Objective To compare the postoperative analgesic efficacy of single doses of dexmedetomidine against fentanyl as epidural adjuvant to 0.125% bupivacaine
Study Groups

Group D: dexmedetomidine (n= 23)

Group F: fentanyl (n= 23)
Inclusion Criteria Consenting American Society of Anesthesiologists I and II patients aged 18–80 years presenting for elective abdominal surgery needing general anesthesia with scope for epidural analgesia
Exclusion Criteria Patients unwilling for epidural, patients on vasopressors after extubation, and those who were ventilated after surgery
Methods Patients received a single epidural bolus of 10 mL 0.125% bupivacaine with either 0.5mcg/kg dexmedetomidine (Group D) epidural bolus or 0.5 mg/kg fentanyl (Group F) epidural bolus. Pain was assessed using the Numerical Rating Scale (NRS), and hemodynamic parameters were monitored. 
Duration December 2015 to April 2016
Outcome Measures

Primary: Duration of postoperative analgesia

Secondary: Hemodynamic variations, vasopressor need, motor blockade
Baseline Characteristics   Dexmedetomidine (n= 23) Fentanyl (n= 23)
Age years 52.2 ± 15.0 57.5 ± 14.6
Male 8 (34.8%) 10 (43.5%)
Height, cm 160.7 ± 8.7 160.0 ± 10.3
Weight, kg 57.6 ± 10.7 61.0 ± 10.6
Duration of surgery, h 5.1 ± 2.2 5.6 ± 1.9
Results   Dexmedetomidine (n= 23) Fentanyl (n= 23) p-value
Duration of pain relief after bolus, h 5.0±2.0 2.9±1.4 <0.001
Hypotension 15 min bolus - No 11 (47.8%) 17 (73.9%) 0.131
Hypotension 15 min bolus - Yes 12 (52.2%) 6 (26.1%) 0.131
Inotropic support - No 7 (30.4%) 16 (69.6%) 0.018
Inotropic support - Yes 16 (69.6%) 7 (30.4%) 0.018
Adverse Events None of the patients had motor blockade or side effects such as nausea, vomiting, or pruritus following epidural bolus.
Study Author Conclusions A single dose of dexmedetomidine as an additive to epidural local anesthetic postoperatively prolongs the duration of analgesia in comparison to fentanyl but is associated with changes in hemodynamics, including the need for the administration of vasoactive drugs.
Critique The study effectively demonstrates the prolonged analgesic effect of dexmedetomidine compared to fentanyl. However, the increased incidence of hypotension and need for vasopressors in the dexmedetomidine group raises concerns about its safety profile. The study's limitations include a small sample size and the lack of long-term follow-up to assess potential delayed adverse effects. 
References:
[1] Sekhar DP, Kumar L, Kesavan R, Purushottaman S, Mohammed ZU, Rajan S. Comparison of the Analgesic Efficacy of a Single Dose of Epidural Dexmedetomidine versus Fentanyl as an Adjuvant to Bupivacaine in Abdominal Surgery. Anesth Essays Res. 2019;13(3):465-470. doi:10.4103/aer.AER_102_19