Effect of interscalene brachial plexus block with dexmedetomidine and ropivacaine on postoperative analgesia in patient undergoing arthroscopic shoulder surgery: A randomized controlled clinical trial

Abstract

Background

Dexmedetomidine, a potent and highly selective α2-adrenoreceptor agonist has become a popular adjuvant to local anesthetics. The study was designed to explore the effect of dexmedetomidine added to ropivacaine for interscalene brachial plexus block (IBPB) on postoperative analgesia in patient undergoing arthroscopic shoulder surgery.

Methods

Forty four adult patients undergoing arthroscopic shoulder surgery were randomly divided into 2 groups. Group R received 0.25% ropivacaine alone, whereas group RD received 0.25% ropivacaine and 0.5 µg/kg dexmedetomidine. A total volume of 15 ml was administered in ultrasound-guided IBPB in both groups. Duration of analgesia, Visual analogue scale (VAS) pain score, frequency of PCA pressed, first time of PCA pressed, sufentanil consumption, and patient satisfaction with analgesia quality were recorded.

Results

Compared with group R, duration of analgesia was prolonged (8.25±1.76 vs. 11.55±2.41 h; P < 0.05), VAS pain scores was decreased at 8 and 10 h postoperatively (3(2–3) vs. 0(0–0) and 2(2–3) vs. 0(0-2.25), respectively; P < 0.05), the frequency of PCA pressed was decreased at 4–8 and 8–12 h time intervals (0(0-0.25) vs. 0(0–0) and 5(1.75-6) vs. 0(0–2), respectively; P < 0.05), the time of first PCA pressed was prolonged (9.27±1.85 vs. 12.98±2.35 h; P < 0.05), the total 24h sufentanil consumption was reduced (108.72±15.92 vs. 94.65±12.47 µg; P < 0.05 ) and patient satisfaction score was also improved (3(3–4) vs. 4(4–5); P < 0.05) in group RD.

Conclusion

We conclude that adding 0.5 µg/kg dexmedetomidine to 0.25% ropivacaine for IBPB provided better postoperative analgesia, decreased the sufentanil consumption and improved the patient’s satisfaction in patients undergoing arthroscopic shoulder surgery.

1. Introduction

Arthroscopic shoulder surgery is a common orthopedic procedure performed to treat different shoulder pathologies. Due to the significant advancements in arthroscopic techniques, arthroscopic shoulder surgery is being characterized as a “minimally invasive” procedure.¹ However, it is often associated with moderate to severe postoperative pain that may have a negative influence on patients’ satisfaction, rehabilitation and potentially increase length of hospital stay.²

Postoperative pain after arthroscopic shoulder surgery has been managed with the use of patient-controlled intravenous analgesia (PCIA), but the opioids most frequently used in PCIA are associated with adverse effects such as nausea and vomiting, respiratory depression, prutitus, urinary retention, and constipation.^3–5 In view of this consideration, investigating a multimodal pain strategy, which can achieve successful pain management while minimize opioids usage is recommended.

The brachial plexus provides sensory and motor innervations for the entire upper extremity.⁶ Therefore, the interscalene brachial plexus block (IBPB) can provide superior analgesic efficacy and be considered as the gold standard for pain management after arthroscopic shoulder surgery.^7,8 However, one obvious disadvantage of single-shot IBPB is the short duration of analgesia, which can be addressed by adding various adjuvants to local anesthetics (midazolam, clonidine, hydromorphone, Dexamethasone and sufentanil).^9–13

Dexmedetomidine, a highly selective and potent α2-adrenoceptor agonist, has shown sedative, anxiolytic, analgesic, anti-hypertensive and sympatholytic properties.¹⁴ Recent clinical trials have found that adding dexmedetomidine to ropivacaine for intercostal nerve block or femoral nerve block could provide superior postoperative pain control to ropivacaine alone.^15,16 On the basis of adding dexmedetomidine to ropivaciane could prolong the duration of analgesia, we hypothesized that adding dexmedetomidine to ropivacaine in IBPB could enhance the analgesic efficacy of ropivacaine. Therefore, we designed a prospective, double-blinded, randomized study to assess the analgesic effect of dexmedetomidine added to ropivacaine for IBPB in patients undergoing arthroscopic shoulder surgery.

2. Materials And Methods

Patients

This study was approved by the Hospital Ethics Committee of the First People’s Hospital of Lianyungang (KY-20210423006) and written consent was obtained after informing the participants about the nature, scope and risks related to the study. The study was also registered with Chinese Clinical Trials Registry (ChiCTR2100046470). Patients of either sex, with Society of Anesthesiologists (ASA) I or II, between 18 and 65 years of age scheduled for elective arthroscopic shoulder surgery undergoing general anesthesia were eligible. The exclusion criteria were as followings: refused to receive IBPB, body mass index > 30 kg/m², history of severe cardiovascular and respiratory disease, renal or hepatic failure, uncontrolled diabetes, allergy to any of the study drug, and contraindications to brachial plexus block (coagulopathy or local infection).

Study Design and Randomization

A statistician who was not involved in the study conducted the randomization of patients into group R (ropivacaine administration) or group DR (dexmedetomidine and ropivacaine administration) on a 1:1 ratio using a computer-generated random number table. The information regarding group assignment was placed in an opaque sealed envelope. After the patient entering into the operation room and prior to the induction of anesthesia, the numbered envelope was opened and the card inside determined into which group the patient was placed.

In Group R; patients received IBPB using 0.25% ropivacaine15 ml. Group RD; patients received IBPB using 0.25% ropivacaine and 0.5 µg/kg dexmedetomidine 15 ml. The anesthetic solutions for IBPB were prepared by an anesthesiology nurse who was not involved in the study. The anesthesiologist performing the block and observing the patient was blinded to the treatment group. Data collection was done by the same anesthesiologist who was unaware of the group allocation.

Procedure of anesthesia

None of the patients were premedicated. After entering the operation room, the patients received routine electrocardiogram (ECG), pulse oxygen saturation (SpO₂), blood pressure (BP), heart rate (HR), and bispectral index (BIS) monitoring. A 20-gauge cannula was inserted into the dorsum of the patient’s hand and connected to a T-connector for drug administration; Ringer lactate was infused at a rate of 4–6 ml/min. General anesthesia was standardized for all patients in both groups. Patients were preoxygenated with 100% oxygen for 3 minutes, followed sufentanil 0.5 µg/kg, propofol 2 mg/kg was intravenously administered and cisatracurium 0.2 mg/kg was given to facilitate tracheal intubation. Anesthesia was maintained with sevoflurane/O₂ /air mixture to keep BIS values between 40 and 60, muscle relaxation was provided using IV cisatracurium. All surgical interventions were performed by the same surgical team.

Procedure of IBPB

The patient was in the supine position with the head slightly turned away from the operative side. Skin was prepared using antiseptic solution, and transducer was wrapped in a sterile cover. A 6-13-MHz high-frequency linear probe of the ultrasound (Philips CX50, Philips Ultrasound, Inc., Bothell, WA, USA) was used to identify the C5-C6-C7 nerve roots of the brachial plexus, which appeared as three beads that were approximately vertically aligned between the anterior and middle scalene muscles on the ultrasound image.¹⁷ Then a 21G*100mm insulated needle (UniPlex NanoLine, Pajunk, Geisingen, Germany) was advanced via the lateral-to-medial approach to target the nerve root, and then ropivacaine alone or ropivacaine with dexmedetomidine was injected around the nerve root. All nerve blocks were performed by anesthesiologists who were experts in performance of ultrasound-guided nerve blocks. After completion of the nerve block and reversal of neuromuscular blockade effect, the trachea will be extubated. Then the patient was transferred to the post-anesthesia care unit (PACU).

Postoperative Pain Control

All patients received intravenous sufentanil with an intravenous patient-controlled analgesia (PCA) system at the end of surgery. The mode of PCA was a bolus of sufentanil 0.05µg/kg, a lockout time of 15 min, and a continuous infusion of sufentanil 0.04µg/kg/h (total regimen 2µg/kg/100 ml). The patients were taught to push the button of the PCA system to receive a bolus of sufentanil each time pain occurred. If the visual analogue scale (VAS) score was ≥ 4, 40 mg parecoxib sodium was injected intravenously as a rescue analgesic.

Studied Variables

Duration of analgesia was defined as the time interval between the completion of IBPB and the time when the patient complained of shoulder pain, and was noted every 30 min since the completion of the IBPB for 4 hours.

The VAS (0–10) pain score (VAS; where 0 = no pain and 10 = worst imaginable pain) was assessed at 2, 4, 6, 8, 10, 12 and 24 h after surgery.

Frequency of PCA pressed was recorded at T0-4、T4-8、T8-12、T12-16、T16-20、T20-24 h postoperatively. The first time of PCA pressed and the total 24h sufentanil consumption were also recorded.

Patient satisfaction with analgesia quality 24 h post-surgery (Number ricrating scale, NRS 1–5; 1, very dissatisfied; 2, dissatisfied; 3, slightly dissatisfied; 4, quite satisfied; 5, completely satisfied) was recorded.

The primary outcome measure in this study was the duration of analgesia. The secondary outcome measures included VAS pain score, frequency of PCA pressed, first time of PCA pressed, total 24h sufentanil consumption, and patient satisfaction with analgesia quality .

Statistical analysis

The sample size was calculated on the basis of a pilot study taking a mean value of 8.0 h and SD 1.78 h for the duration of postoperative analgesia in 10 patients who received IBPB with ropivacaine. A 20% difference in the duration of the postoperative analgesia was considered a clinically relevant difference. For a 2-group t test with α = 0.05, β = 0.2 and 2-sided significance level, we required 21 patients in each group. A total of 50 patients were recruited in the study to compensate for possible dropouts.

Statistic tests were performed using SPSS 16.0 for windows (SPSS 16, Chicago, IL, USA). Continuous numerical data were expressed as mean and standard deviation, or median and interquartile range. Categorical data were expressed as frequencies and percentages. Normally distributed numerical data between groups were analyzed using the independent 2-sample t-test. Skewed data between groups were analyzed using the Mann–Whitney U-test. Categorical variables were analyzed using the Fisher’s exact test or the Pearson’s Chi-square test as applicable. All tests were two-tailed. P < 0.05 was considered statistically significant.

3. Results

Among the 50 patients who were eligible for the study, 4 patients refused to participate in the study, 2 patients received open surgery. Of the remaining 44 patients, 22 patients were randomized to group R and 22 patients were randomized to group RD (Fig. 1).

There were no differences between groups with respect to demographic data and the operation time (Table I).

The VAS pain scores increased gradually after surgery, due to the analgesic effect of the IBPB faded gradually. The VAS pain scores were significantly lower in group RD at 8 and 10 h postoperatively compared with those in group R. However, there were no significant differences in pain scores between the two groups at 2, 4, 6, 12 and 24 h time points.

The frequencies of PCA pressed were less in group RD than that in group R at 4–8 and 8–12 h time intervals (P < 0.05). However, there were no significant differences in frequencies of PCA pressed between the two groups at 0–4, 12–16, 16–20, and 20–24 h time intervals (P < 0.05). (Table III)

Compared with group R, the duration of analgesia and first time of PCA pressed were longer than that in group RD (P < 0.05). Meanwhile, the total 24h sufentanil consumption in group R was more than that in group RD (P < 0.05). Patient satisfaction score was also higher in group RD (P < 0.05). (Table IV)

4. Discussion

In this prospective, randomized, controlled study, we found that the addition of dexmedetomidine to ropivacaine for IBPB significantly prolonged the duration of postoperative analgesia, prolonged the first time of PCA pressed, reduced the consumption of sufentanil and improved the patient’s satisfaction in patients undergoing arthroscopic shoulder surgery.

The interscalene brachial plexus block is a commonly used regional anesthesia technique, it has been considered as a standard treatment in managing pain after shoulder surgery.¹⁸ Ultrasound technology has aided anesthetists in depositing local anesthetics in precise proximity to targeted peripheral nerves, so there is no need to use large volume of local anesthetics for IBPB. Meanwhile, Studies have demonstrated that local anesthetic volumes of 20 ml or more may associate with high incidence of hemidiaphragmatic paresis after interscalene brachial plexus block,¹⁹ although it can be resolved by decreasing local anesthetic volume to 5 to 10ml, this may result in a clinically significant reduction in the duration and potency of perioperative analgesia and may also lead to a high risk of block failure.^19–21 Thus we used 15ml of 0.25% ropivacaine for IBPB in our study; this is also consistent with the does and concentrations of ropivacaine reported in other centers. ^{22, 23}

Dexmedetomidine, a highly selective α2 adrenoreceptor agonist, has a potency to ameliorate pharmacodynamic characteristics of peripheral anesthetic technique, it is currently the most widely used additive drug in regional anesthesia. Sharma et al. reported that addition of dexmedetomidine 0.75 µg/kg to 0.5% ropivacaine results in early onset of sensory and motor blockade, prolongation of duration of sensory and motor blockade and duration of analgesia postoperatively without any significant side effects.²⁴ Singh et al. demonstrated that dexmedetomidine fasten the onset time of sensory and motor block, prolong the block and analgesia duration when it was used as adjuvant to ropivacaine for supraclavicular brachial plexus block.²⁵ Koraki et al. reported that dexmedetomidine 100 µg as adjuvant on ultrasound-guided axillary plexus block significantly prolonged the duration of sensory block and analgesia, as well as accelerated the time to onset of sensory block.²⁶ Nazir et al. suggested that 1 µg/kg dexmedetomidine as adjuvant to 0.25% bupivacaine in supraclavicular block resulted in faster action, prolonged motor and sensory block, prolonged analgesia.²⁷ All of these previous studies demonstrated dexmedetomidine could accelerate the onset time of sensory-motor block; prolong the durations of sensory-motor block and analgesia.

In our study, the results showed that compared with 0.25% ropivacaine alone, adding 0.5µg/kg dexmedetomidine to 0.25% ropivacaine in IBPB prolonged the duration of analgesia approximately 3.5 hours in average (8.25 vs. 11.55), Postoperative VAS pain scores were comparable in both groups except at 8 and 10 hours postoperatively, when the VAS pain scores were lower in group RD compared with group R. Our result was consistent with the result showed by Bharti et al, which indicated that addition of dexmedetomidine to ropivacaine-lidocaine prolonged the duration of supraclavicular brachial plexus block about 5 hours (12 vs. 17) and also reduced VAS pain scores at 8 and 10 hours postoperatively.²⁸ Different from the previous studies, we did not assess the onset time and duration of sensory and motor block. The reasons are as followings; Firstly, the IBPB was performed after the completion of the surgery, and the trachea will not be extubated until the block was finished and the neuromuscular blockade effect was reversed, so it was difficult to assess the exact onset time of sensory and motor block. Secondly, the surgical site was covered with wound dressings and the patient was recommended to wear a shoulder brace for 6 weeks immediately after this surgery, so it was inconvenient to assess the duration of sensory and motor block.

Patient-controlled analgesia (PCA) is one of the well established methods for providing postoperative analgesia, a key component for implementing multimodal analgesia. PCA has been proven to be more effective at pain control than non-patient opioid injections and can result in higher patient satisfaction.²⁹ Peng et al. demonstrated that intravenous patient-controlled analgesia was related to improved survival, less complications and chronic post-surgical pain after major abdominal surgery, reiterating the important role of pain management for the prognosis of patients who underwent surgery. ³⁰ Tai et al. reported that patients using intravenous PCA had a better quality of life in physical health over time after major surgery.³¹ Therefore; we used PCA and IBPB as the postoperative analgesic method for arthroscopic shoulder surgery in our study. In fact, in our study there was no patient required rescue analgesic, which demonstrated our analgesia strategy is successful. Meanwhile, our results showed that dexmedetomidine added to ropivacaine for IBPB prolonged the first time of PCA pressed, decreased the frequency of PCA pressed at 4–8 and 8–12 h time intervals, reduced the total 24h sufentanil consumption, and improved the patient’s satisfaction. Yang et al. reported that the transversus abdominis plane block reduced morphine consumption in the first 24 h following renal transplantation, and the addition of dexmedetomidine provided a more effective analgesic effect.³² A meta-analysis also revealed that it is effective and safe for dexmedetomidine as an adjunct to local anesthetics in nerve block in TKA to relieve postoperative pain, decrease total opioid consumption, prolong analgesic duration, and increase patient satisfaction without increasing related complications.³³ Our results were similar with that showed in the above two studies. All of these results indicated that dexmedetomidine added local anesthetics decreased the opioid consumption and provide a better postoperative analgesia.

Limitations

The present study does have some limitations. First, the study was conducted at a single center and the sample size was relatively small, so the conclusions can not be generalized. Further studies at multiple centers are required to generalize the results. Second, the assessment of VAS pain scores is expected to last for 24 hours, especially at the 10h and 24h postoperatively time points, the patient may fall asleep, so the assessment may disrupt the patients’ sleep and impair the patients’ postoperative recovery. Third, it is a standard practice in our center to use 15 ml of 0.25% ropivacaine for IBPB, additional studies are required to research different dosages and concentrations of local anesthetics for IBPB.

5. Conclusion

Dexmedetomidine (0.5µg/kg) added to ropivacaine(0.25%) for interscalene brachial plexus block significantly prolonged the duration of postoperative analgesia, prolonged the first time of PCA pressed, reduced the consumption of sufentanil and improved the patient’s satisfaction in patients undergoing arthroscopic shoulder surgery.

Declarations

Ethics approval and consent to participate

Ethical approval was provided by the ethics committee of the First People's Hospital of Lianyungang (LCYJ202010002). Each patient signed an informed consent.

Consent for publication

Not applicable.

Availability of data and material

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Funding

This study was funded by the Ph.D Science Research Startup Foundation of the First People’s Hospital of Lianyungang (BS202005) and the Science Research Development Foundation of Kangda College of Nanjing Medical University (KD2021KYJJZD031).

Author Contributions

Hengfei Luan and Conghui Hao designed the study, performed the femoral nerve blocks and wrote the first draft of the manuscript. Han Li and Xiaobao Zhang collected, analyzed the data and interpreted the results. Zhibin Zhao and Pin Zhu revised the manuscript. All authors read and approved the final version of the manuscript.

Competing Interests

The authors reported no conflicts of interest in this study.

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Tables

 Table III Comparison of frequency of PCA pressed between the two groups at different time intervals

 Table IV Comparison of postoperative variables between the two groups