Analgesic effect of dexamethasone combined with ropivacaine for thoracic paravertebral nerve block on patients undergoing thoracoscopic lobectomy：A randomized，double-blinded clinical trail

Abstract

Background

Far from now, there is still a lack of studies on dexamethasone combined with ropivacaine for ultrasound-guided thoracic paravertebral block (TPVB). Our study aims to observe the analgesic effect of 0.2mg/kg dexamethasone combined with ropivacaine for TPVB on patients undergoing thoracoscopic lobectomy to evaluate postoperative analgesic effect of the compound and prgnosis of patients.

Methods

92 patients who underwent thoracoscopic lobectomy from August 2020 to March 2021 were randomly divided into ropivacaine group (group R) and dexamethasone combined with ropivacaine group (group RD), 46 cases in each group. The group R was performed thoracic paravertebral block with 20ml 0.5% ropivacaine, then the group RD was injected with 20ml of 0.2mg/kg dexamethasone and 0.5% ropivacaine mixture, and general anesthesia induction was performed 30 minutes after the completion of thoracic paravertebral nerve block. The onset time and width of sensory block were observed and recorded. VAS scores were recorded at 1h(T₁), 6h(T₂), 12h(T₃) and 24h(T₄). Additional analgesic and sedative drugs for salvage use within 24 hours after operation were recorded. The preoperative fasting glucose level and the postoperative one-day fasting glucose level were recorded. The incidence of side-effects such as skin pruritus, nausea and vomiting were recorded. The extubation time of tracheal intubation and total hospital stay were recorded.

Results

There was no significant difference in the onset time and width of sensory block between the two groups(P > 0.05); The VAS scores at T₁, T₂, T₃ and T₄ in group RD were significantly lower than group R(P < 0.05); Compared with group R, the proportion of patients in group RD who received additional morphine rescue analgesia within 24 hours after operation was significantly lower(P < 0.05); while the proportion of patients who received additional midazolam sedation had no significant difference(P > 0.05); The incidence of postoperative nausea and vomiting was similar between the two groups(P > 0.05); There was no significant difference between the preoperative fasting blood glucose and the postoperative one-day fasting blood glucose in group R(P > 0.05); The fasting blood glucose showed an increase on the first day after operation than that before operation in group RD(P < 0.05); Compared with group R, the extubation time in group RD was significantly shorter(P < 0.05); There was no significant difference in surgery time, total propofol and remifentanil assumption during surgery, and total length of hospital stay between group R and group RD as well(P > 0.05).

Conclusion

0.2mg/kg dexamethasone combined with ropivacaine for TPVB can significantly enhance the analgesic effect of ropivacaine in nerve blocks, provide effective and comprehensive postoperative analgesia for patients undergoing thoracoscopic lobectomy, shorten extubation of tracheal tube after operation, and with no increasing incidence of side effects, but exhibit rare influence on the extent of nerve block and total length of hospital stay.

Clinical trial registration:

No. ChiCTR2000033956, registrated at the Chinese Clinical Trial Registry, principal investigator: Xiaopei Gao, date of registration: 18/06/2020.

Introduction

Although thoracoscopic lobectomy causes minor trauma to patients, while the pleural surfaces of the diaphragm, pericardium, and mediastinum are stimulated continuously by operative procedures during the whole course of operation, contributing damage to those tissues. Besides, endoscopic operation will also cause certain damage to intercostal nerve, resulting in acute and chronic post-surgical pain [1]. Comprehensive postoperative analgesia can reduce many complications induced by postoperative pain, promote the recovery of lung function, and improve the outcomes of patients. Previous studies have proved that thoracic paravertebral nerve block (TPVB) can provide ideal analgesic effect by blocking the nerve conduction on operative side [2, 3]. Ropivacaine performs as a medium-long-acting local anesthetic with advantages of little cardiac toxicity and long-term effect, which is generally used in intraoperative and postoperative analgesia, but there still exist some disadvantages, such as insufficient postoperative analgesia time, toxic effects [4]. Adjuvants have been comfirmed when combined with ropivacaine, the analgesic strength and duration of ropivacaine inhanced, side-effects and complications decreased [5]. Dexamethasone is a commonly used glucocorticoid in clinic, which has been proved that dexamethasone combined with various local anesthetics can enhance the analgesic effect of local anesthetics for nerve block, prolong the duration, and diminish side-effects [6]. There are still a minor variety studies focusing on the analgesic effect of dexamethasone combined with ropivacaine for thoracic paravertebral block. In our study, 0.2mg/kg dexamethasone combined with ropivacaine for thoracic paravertebral block was used in thoracoscopy lobectomy to evaluate the postoperative analgesia effect.

Materials And Methods

The study was approved by the Affiliated Hospital of North Sichuan Medical College ethics committee (Ethics batch number 2019ER(R)111-1), registered in China clinical trial center (No. ChiCTR2000033956, date of registration: 18/06/2020, http://www.chictr.org.cn/index.aspx), and signed the informed consent form with the patient or his/her relatives-in-law. After finishing written informed consent, 92 ASA grade I-II patients in the age of 18 ~ 65 year, who were undergoing thoracoscopic lobectomy with TPVB and general anesthesia between August 2020 to March 2021, were included. The 92 included subjects were randomly grouped using SPSS 26.0 software and finally 80 patients who met the inclusion creteria were included in statistical analysis. The group allocation numbers were concealed in sealed opaque envelopes that were opened after enrollment of the patients. Patients those who met the cardiovascular system dysfunction; congenital heart disease; abnormal coagulation function; mental illness; patients who used the drugs that affect the immune function in past 4–6 weeks; there were contraindications to operation or anesthesia; allergic to ropivacaine or dexamethasone; incomplete clinical data; those who refused to participate, were excluded. Patients with cardiovascular and cerebrovascular accidents during and after operation; patients chose to withdrawn anytime during the study; patients who failed thoracic paravertebral block; were excluded from the study.

All patients were fasting for 8h and banned drinking for 4h before operation and no preoperative medication was given. Oxygen inhalation (3L/min) was given by mask after entering the operation room. ECG, NIBP, HR and SpO₂ were routinely monitored, and peripheral venous access was opened using a 18G catheter. Then TPVB was performed, patients took the operation position, disinfected and spread the towel, the low-frequency (2 ~ 5MHz) curved probe was protected with a sterile cover, and performed TPVB under ultrasound guidance (Mindary UMT-900, Shenzhen, Guangdong, China). After local anesthesia with 1% lidocaine at the puncture site, a 22G, 120mm needle (Stimuplex D; B.Braun Melsungen, Germany) was held in the right hand, and the puncture was performed with the long-axis planar technique of thoracic paravertebral block, and a piece of silver chloride electrode was placed on the anterolateral chest wall of the patient, connecting the peripheral nerve stimulator (Stimuplex HNS12; B.Braun Melsungen, Germany), set the initial parameter of the stimulator to 1mA, and stroke nerve block puncture needle to enter the space vertically. Firstly, the paravertebral muscle contraction can be observed, and the needle continues to deepen until it reaches the transverse costal ligament. At the time, the paravertebral muscle contraction will stop suddenly. The intercostal muscle contraction of the corresponding segment can be observed after the needle tip passes through the tough transverse costal ligament. Then the needle tip stops moving forward, and sets the parameter of stimulator to 0.4-0.6mA. Under current condition, if the intercostal muscle still contracts strongly, indicating that the needle tip reaches the appropriate thoracic paravertebral space. Local anesthetics were injected at a constant speed (3-4ml/20s), and the single-point block method was selected according to the costal space of the surgical incision. After finishing nerve block, patients returned to supine position. Successful block was defined as acupuncture hypoesthesia in 5 ipsilateral skin segments or more within 30 minutes and no sensory block in the contralateral skin.

After TPVB finished, all patients were induced by intravenous injection of midazolam 0.08 ~ 0.12mg/kg, sufentanil 0.4ug/kg, etomidate 0.2 ~ 0.3mg/kg and cis-atracurium 0.15mg/kg. After 3 minutes of assisted-breathing, a double-lumen tracheal tube was inserted orally directed by a visual laryngoscopy, and location of the two sets of bursal were examined and confirmed by fiberoptic bronchoscopy. The white-cuff should be adjusted to the bifurcation of the tracheal carina, and the blue-cuff should be located in the healthy lung and the opening of each bronchial lobe should be visible. After the location of the catheter was determined, the catheter was fixed, and the oxygen flow was set as 1.0 ~ 1.5L/min. After single-lung ventilation, the tidal volume was set to 6 ~ 8ml/kg, the respiration rate was 10 ~ 14 times/min, the inhalation/exhalation(I/E) ratio was 1:2, and the end-of-expiratory partial pressure of carbon dioxide (P_ETCO₂) was maintained to 35 ~ 45mmHg.

The concentration of sevoflurane was 1%, propofol was injected intravenously at 2 ~ 6mg/kg·h, remifentanil 0.5 ~ 2ug/kg·h, and CIS-atracurium was injected intermittently. The pump speed of propofol and remifentanil was adjusted to maintain BIS score at a fluctuaion of 40 ~ 60. The fluctuation range of heart rate (HR) and median arterial pressure (MAP) was no more than 20% of the basic value; Atropine was injected intravenously at the time of bradycardia (HR < 50 times/min), while ephedrine was injected 6-9mg when BP was lower than 20% in operation (SBP < 90mmHg or SBP was lower than 20% compared with the basic value).

After the operation finished, patients were transferred to postoperative care unit and ECG, NIBP, HR and SpO₂ were routinely monitored. Tracheal catheter can be extubated when meet extubation criteria: 1. The patients’ awareness recovered and able to consociation; 2. Laryngopharyngeal reflex, swallowing reflex and cough reflex recovered completely; 3. Tidal volume and ventilation capacity per minute returned to normal; 4. There were no incidence of airway obstruction after extubation.

Within 24 hours after surgery, when VAS score exceeded 3 points, morphine 0.05 mg/kg was given to relieve pain by an intramuscular way; when Ramsay Sedation score reached 1, midazolam 0.05 mg/kg was given intravenously to perform sedation compensation.

Results

The research flowchart was depicted in Figure1. We recruited 92 patients into our study, after randomization, the participants received 0.5% ropivacaine only 20ml and 0.5% ropivacaine and 0.2mg/kg dexamethasone mixture 20ml for TPVB before anesthesia induction, respectively, but 7 of them did not meet inclusion criteria and 5 of them refused fully participation, were excluded from our study. Thus, 80 subjects were enrolled into statistical analysis eventually.  

Demographic data and clinical characteristicsin

There were no significant differences in age, weight, height, gender, and ASA grades (Table 1), Onset time and block width of thoracic paravertebral block (Table 2). Compared with R group, VAS scores at different time points (T₁, T₂, T₃, T₄) was lower, respectively (Table 3). What’s more, surgery time among the two groups, total propofol and remifentanil use during surgery, total length of hospital stay among the two groups, incidence of postoperative side-effects and proportion of patients who received rescue sedation within 24 hours (Table 4). The proportion of patients with rescue analgesia was lower as well, the extubation time after surgery was significantly shorter (Table 4). There was no significant difference between the preoperative empty blood glucose level and the postoperative one-day empty blood glucose level in R group, The empty blood glucose level showed an increase on the first day after operation than that before operation (Table 5). 

There was no significant difference in age, weight, height, gender and ASA grades between the two groups (P>0.05, Table 1).

Table 1 General information of two groups.

Data presented as mean ± standard deviation. 

^*P <0.05 vs. Group R, Group R: 0.5% ropivacaine, RD: 0.5% ropivacaine and 0.2mg/kg dexamethasone.

Abbreviations: ASA, American Society of Anesthesiologists, BMI, body mass index.  

There was no significant difference in the onset time and block width of TPVB between group R and group RD (P>0.05, Table 2, figure 1).

Table 2 onset time and block width of thoracic paravertebral block in two groups

Data presented as mean ± standard deviation 

^*P <0.05 vs. Group R, Group R: 0.5% ropivacaine, Group RD: 0.5% ropivacaine and 0.2mg/kg dexamethasone. 

Compared with group R, the VAS scores of T₁, T₂, T₃ and T₄ in group RD were significantly lower（P<0.05, Table 3, figure 2)

Table 3 the VAS scores at different time points (T₁, T₂, T₃, T₄) 

Data presented as mean ± standard deviation. 

^*P <0.05 vs. Group R, Group R: 0.5% ropivacaine, RD: 0.5% ropivacaine and 0.2mg/kg dexamethasone.

Abbreviation: VAS, visual analog scale.

There was no significant difference of surgery time, total propofol and remifentanil use between group R and group RD (P>0.05), Compared with group R, the extubation time after surgery in group RD was significantly shorter (P<0.05), There was no significant difference in total length of hospital stay between group R and group RD (P>0.05). There was no skin pruritus in two groups, and no significant difference in the incidence of nausea and vomiting between the two groups as well (P>0.05). Compared with group R, the probability of additional analgesic drugs within 24 hours after operation in group RD was significantly lower (P<0.05), and there was no difference in the probability of additional midazolam sedation rescue between the two groups (P>0.05, Table 4)

Table 4 Surgery time, total propofol and remifentanil use during surgery of two groups, extubation time of two groups, total length of hospital stay among the two groups, incidence of postoperative adverse reactions and proportion of patients with rescue analgesia and sedation within 24 hours in the two groups.

Table 4 Intraoperative and Postoperative recovery data

Data presented as mean ± standard deviation or numbers(proportion). 

^*P <0.05 vs. Group R, Group R: 0.5% ropivacaine, RD: 0.5% ropivacaine and 0.2mg/kg dexamethasone.

There was no significant difference between the preoperative blood glucose level and the postoperative one day blood glucose level in group R (P>0.05), in group RD, the blood glucose level one day after operation is higher than that before operation(P<0.05), There was no significant difference in the blood glucose level between the two groups before operation (P>0.05), but there was a significant difference in blood glucose level between the two groups one day after operation (P<0.05, table 5, figure 3).

Table 5 Empty blood glucose levels of two groups before and 1 day after operation

Data presented as mean ± standard deviation.

^*P <0.05 vs. Group R, Group R: 0.5% ropivacaine; RD: 0.5% ropivacaine and 0.2mg/kg dexamethasone.

Discussion

In recent years, with the rapid popularization of enhanced recovery after surgery (ERAS), perioperative multimodal analgesia based on regional analgesia to optimize postoperative pain has becoming much more important than ever [7,8]. Thoracoscopic surgery can damage intercostal nerves both directly and indirectly, resulting in severe postoperative pain. Postoperative pain can activate a series of stress reactions, increase the risk of postoperative complications such as cardiovascular and pulmonary vascular complications, and affect the prognosis of patients. Therefore, comprehensive postoperative analgesia seems to be particularly important in reducing the occurrence of complications and improve the prognosis of patients. As researches of thoracic paravertebral space continues to deepen, TPVB technology already become much more mature than before, and its safety and effectiveness have been confirmed. TPVB has the comprehensive analgesic effect of traditional epidural block, and less side-effects, so it is gradually widely used in thoracoscopic surgery and postoperative analgesia, and has performed good influence [9]. Previous studies [10] have shown that a single-point injection of 0.5% ropivacaine can achieve 5 or more segments of block, so our study selected 0.5% ropivacaine for thoracic paravertebral nerve block. It was found that there was no significant difference in the onset time and width of sensory block when ropivacaine combined with 0.2mg/kg dexamethasone. VAS pain scores at all four time-points (T₁, T₂, T₃ and T₄) were decreased in group RD, in addition, the proportion of patients with rescue analgesia within 24 hours after operation decreased significantly, while the proportion of patients with rescue sedation remained unchanged. After compounding dexamethasone, the incidence of side-effects did not change significantly, when combined ropivacaine with dexamethasone, the empty blood glucose level increased, but still in normal range, the extubation time of endotracheal tube was significantly advanced with a combination of ropivacaine and dexamethasone, but the total length of hospital stay was not shortened.

Fujii et al. [11] used 0.3mg/kg dexamethasone combined with ropivacaine for interscalene brachial plexus block, and found that the onset time of sensory and motor block was significantly shortened. However, Shi et al. [12] used 0.1mg/kg dexamethasone combined with ropivacaine for ultrasound-guided cervical plexus block, and found that the onset time of sensory and motor block did not change significantly. In our study, 0.2mg/kg dexamethasone combined with ropivacaine was used for TPVB. It was found that the onset time of TPVB was not significantly shortened, and the block width was not increased, which was consistent with the results of latter study. It demonstrates that high dose(0.3mg/kg) dexamethasone can shorten the onset time of ropivacaine, while low dose dexamethasone has no obvious effect on the onset time of ropivacaine nerve block.

Hu et al. [13] found that 5mg dexamethasone combined with ropivacaine for brachial plexus block delayed the first postoperative analgesia time by 7~35h, and the proportion of patients using analgesic drugs within 48h after operation also decreased significantly, Zhang et al. [14] used 0.2mg/kg dexamethasone combined with ropivacaine for lumbar plexus block, and found that the sensory block time was prolonged by 1~12h, the motor block time was prolonged by 3~9h, and the VAS scores of patients at 2h, 12h and 24h after operation were decreased, all the above studies show that dexamethasone can significantly enhance the analgesic effect of ropivacaine nerve block and prolong the analgesic time. Our results suggested that VAS pain scores of T₁, T₂, T₃ and T₄ in the group RD were significantly lower than those in group R. At the same time, the proportion of patients with additional analgesic drugs in group RD (15%) was significantly lower than that in group R (42.5%). These results indicate that dexamethasone combined with ropivacaine for TPVB can significantly enhance the analgesic effect of ropivacaine, which is consistent with the above results. This mainly relates to the local anesthetic like effect of dexamethasone, because of its strong fat solubility, it can be used as a carrier when mixed with local anesthetics, which slows down the metabolism of local anesthetics. Meanwhile, it can increase the sensitivity of blood vessels to catecholamine, indirectly constrict blood vessels and prolong its effective time. Combining use dexamethasone, it can enhance the analgesic effect of ropivacaine, prolong the analgesia time, relieve the pain and reduce discomfort of patients, and then decrease the number and total amount of postoperative morphine.

We found that 24 hours after operation, the empty blood glucose level of group RD was higher than that before operation, but it did not exceed the normal range of fasting blood glucose, besides there was no skin pruritus. Yuan et al. [14] showed that the empty blood glucose level one day after surgery in 15mg dexamethasone group was too high in psoasquadratus nerve block, which led to skin pruritus and increased infection rate, while the blood glucose level in 10 mg and 5 mg dexamethasone groups was slightly increased within the normal range, and no skin pruritus occurred, high dose dexamethasone can lead to high blood glucose level, increase local skin’s regional sugar content, and cause demyelination of nerve endings, we did not observed hyperglycemia with a compound of 0.2mg/kg dexamethasone in our study, which was consistent with the above findings. The analysis and inclusion were all based on non-DM patients, and the dose selected for our study was relatively small. All of these indicates that dexamethasone can give a lift in empty blood glucose level, which should prudently considered when used for diabetic patients undergoing nerve block, besides, low-dose dexamethasone should be top priority if used. Meanwhile, dexamethasone also acts on the nucleus of solitary tract to provide anti-inflammatory function, reduce the incidence of postoperative nausea and vomiting (PONV). However, the results of our study were inconsistent with the above results. There were 8 cases of PONV in group R and 4 cases in group RD respectively. Obviously, there was no significant difference in the side-effects between the two groups (P>0.05). Our study showed that a combination of 0.2mg/kg dexamethasone with ropivacaine did not increase the side-effects and had certain safety.

Kumar et al. [15] showed that 10mg dexamethasone combined with ropivacaine for serratus anterior plane block can significantly shorten the extubation time of patients after operation, the results showed that the extubation time of dexamethasone group was significantly shorter than that of saline group, which was consistent with the above study. After combining dexamethasone, the analgesic effect of ropivacaine enhanced, which is helpful to promote the recovery of respiratory function in early postoperative period. The results showed that the total length of hospital stay in group R was similar to group RD, suggesting that dexamethasone combined with dexamethasone could not advance the discharge time of patients, thus shortening the total length of hospital stay, the proper explanation for this phenomenon may be our study only intervened in single aspect, and the factors affecting the postoperative outcome of patients are diverse and complex, suggesting there is a necessity to improve the prognosis and outcome of patients from various aspects.

The limitations of this study are as follows: 1. The single-point injection method of thoracic paravertebral nerve tissue was used in our study, and the effect of multi-point injection method on block width has not been explored, 2. In our study, dexamethasone combined with ropivacaine was used in a single dose, and it did not shorten the onset time of sensory block or widen segments of blocking, 3. In our study, we did not observe the pain score in exercise state and the stress response level in perioperative period, 4. Diabetes patients was not included in our study, and the effects of dexamethasone on diabetes mellitus and prognosis were not fully explored. Therefore, we can take multi-point injection method, use different doses of dexamethasone and include a variety of observation groups to improve the experimental research.

Conclusion

Dexamethasone combined with ropivacaine can significantly enhance the analgesic effect of ropivacaine in TPVB, provide effective and comprehensive postoperative analgesia for patients undergoing thoracoscopic lobectomy, shorten the time of tracheal extubation, and do not increase the incidence of adverse reactions such as PONV, agitation, but did not widen the extent of block and had no significant effect on the total length of hospital stay.

Abbreviations

group R：0.5% ropivacaine 20ml only；group RD：20ml of 0.2 mg/kg dexamethasone and 0.5% ropivacaine mixture；TPVB：Thoracic paravertebral block；PONV：Postoperative pain and postoperative nausea and vomiting；VAS：Visual analogue scale；HR：Heart rates；NIBP：Non-invasion blood pressure；SpO2：Pulse oximetry；ECG：Electrocardiography；P_ETCO₂：End-tidal carbondioxide；BIS：Bispectral index

Declarations

Acknowledgements

Not applicable.

Authors’ contributions

XPG and DLK helped to designthe study, conduct the study, analyze the data, search literature and write the manuscript. FJW helped to supervise the study and give the critical review to the study. Kaiyue Zheng helped to design the study, conduct the study and analyze the data. Hui Zhong, Wuchang Fu helped to analyze the data. All authors have read and approved the manuscript.

Funding

Conduct of the study and publication of the manuscript was supported by Science and Technology Foundation of Sichuan Provincial Health Commission, No.17PJ215. The funding body plays a role in collection and analysis of data.

Availability of data and materials

The data sets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent for participation

This study was approved by the Ethics Committeeofthe Affiliated Hospital of North Sichuan Medical College(2019ER(R)111-1) and written informed consent was obtained from all subjects participating in the trial. The trial was registered prior to patient enrollment at the Chinese Clinical Trial Registry, (No.ChiCTR2000033956, Principal investigator: Xiaopei Gao, date of registration: 18/06/2020). All methods were performed in accordance with the relevant guidelines and regulations.

Consent for publication

Consent for publication has been sought from all the authors listed.

Competing interests

There is no competing interest.

Author details

¹Department of Anesthesiology, The Affiliated Hospital of North Sichuan Medical College, No. 1, Maoyuan Road, Shunqing District, Nanchong City, Sichuan Province, China.

References

1. Mao Yu, Zuo Youmei, Mei Bin, et al. Efficacy of perineural dexamethasone with ropivacaine in thoracic paravertebral block for postoperative analgesia in elective thoracotomy: a randomized, double-blind, placebo-controlled trial. J Pain Res, 2018, 11: 1811-1819.
2. Liu Fei, Zhang Huan-Kai, Zuo Yun-xia, Bilateral thoracic Paravertebral block for immediate postoperative pain relief in the PACU: a prospective, observational study. BMC Anesthesiol, 2017, 17: 89.
3. Casati A, Alessandrini P, Nuzzi M, et al. A prospective, randomized, blinded comparison between continuous thoracic paravertebral and epidural infusion of 0.2% ropivacaine after lung resection surgery.Eur J Anaesthesiol, 2006, 23: 999-1004.
4. Mao Yu, Zuo Youmei, Mei Bin, et al. Efficacy of perineural dexamethasone with ropivacaine in thoracic paravertebral block for postoperative analgesia in elective thoracotomy: a randomized, double-blind, placebo-controlled trial.J Pain Res, 2018, 11: 1811-1819.
5. Zorrilla-Vaca Andres, Li Jinlei. Dexamethasone Injected Perineurally is More Effective than Administered Intravenously for Peripheral Nerve Blocks: A Meta-Analysis of Randomized Controlled Trials. Clin J Pain, 2018, 34: 276-284.
6. Jiang Xiao-Juan, Li Zi, Li Qi, et al.Comparison of single-injection ultrasound-guided thoracic paravertebral block with transversus abdominis plane block in peritoneal dialysis catheter implantation: a randomized controlled trial. Trials, 2021, 22: 266.
7. Xu Zhen-Zhen, Li Xue, Zhang Zhen, et al. Ultrasound-guided erector spinae plane block versus thoracic paravertebral block on postoperative analgesia after laparoscopic nephroureterectomy: study protocol of a randomized, double-blinded, non-inferiority design trial. Trials, 2021, 22: 249.
8. Jain Dhruv, Mohan Virender K, BhoiDebesh, et al. Analgesic efficacy and spread of local anesthetic in ultrasound-guided paravertebral, pectoralis II, and serratus anterior plane block for breast surgeries: A randomized controlled trial. Saudi J Anaesth, 2020, 14: 464-472.
9. ChoiEun Kyung, Kim Ji-Il, Park Sang-Jin. A Randomized Controlled Trial Comparing Analgesic Efficacies of an Ultrasound-Guided Approach with and without a Combined Pressure Measurement Technique for Thoracic Paravertebral Blocks After Open Thoracotomy. Ther Clin Risk Manag, 2020, 16: 727-734.
10. Zhang Hai-Yan, Jiang Xiao-Juan, Li Qi, et al. Single-Injection Ultrasound-Guided Thoracic Paravertebral Block versus Local Anesthetic Infiltration in Peritoneal Dialysis Catheter Surgeries: A Randomized Controlled Trial. Blood Purif, 2020, 49: 426-433.
11. Fujii Tasuku, Shibata Yasuyuki, Ban Yasutaka, et al.A single paravertebral injection via a needle vs. a catheter for the spreading to multiple intercostal levels: a randomized controlled trial. J Anesth, 2020, 34: 72-78.
12. Hong Boohwi, Lim ChaeSeong, Kang Hyemin, et al. Thoracic Paravertebral Block with Adjuvant Dexmedetomidine in Video-Assisted Thoracoscopic Surgery: A Randomized, Double-Blind Study. J Clin Med, 2019, 8: undefined.
13. Woo Jae Hee, Kim YounJin, Kim Dong Yeon, et al. Dose-dependency of dexamethasone on the analgesic effect of interscalene block for arthroscopic shoulder surgery using ropivacaine 0.5%: A randomised controlled trial. Eur J Anaesthesiol, 2015, 32: 650-5.
14. Yuan Qing, Cui Xulei, Fei Yuda, et al. Transmuscular quadratus lumborum block versus thoracic paravertebral block for acute pain and quality of recovery after laparoscopic renal surgery: study protocol for a randomized controlled trial. Trials, 2019, 20: 276.
15. Kumar Vinod, Sirohiya Prashant, Gupta Nishkarsh et al. Effect of adding dexamethasone to ropivacaine for ultrasound-guided serratus anterior plane block in patients undergoing modified radical mastectomy: A preliminary trial. Indian J Anaesth, 2020, 64: 1032-1037.