The Effects of Erector Spinae Plane Block on Perioperative Opioid Consumption and Rehabilitation in Video Assisted Thoracic Surgery

Abstract

Background The present study aimed to observe whether the ultrasound-guided continuous erector spinae plane block (ESPB) has an effect on opioid consumption and postoperative rehabilitation in patients who undergo video-assisted thoracic surgery (VATS).

Methods In this prospective study, 120 patients aged 20–70 yrs, undergoing elective VATS, were randomly allocated to one of three groups: Group C (General anaesthesia with patient-controlled intravenous analgesia [PCIA]), Group T (General anaesthesia with patient-controlled epidural analgesia [PCEA]), or Group E (General anaesthesia with continuous ESPB and PCIA). The perioperative opioid consumption; VAS scores; preoperative and postoperative QoR-15 score; and postoperative opioid-related adverse events were all assessed.

Results The intraoperative sufentanil consumption in group T and E was significantly lower than that in group C (both P < 0.001), and the postoperative sufentanil consumption in group E was also significantly lower than that of group C (P = 0.001). Compared with group C, the VAS scores at rest or during coughing immediately out of the post-anesthesia care unit (PACU), at postoperative 6h, 12h, and 24h, were significantly lower in group T (P < 0.05). However, the VAS scores in group E were lower than those of group C only at rest at postoperative 6h and 12h (P < 0.05), and were significantly higher than those of group T at all study times (P < 0.05).

Conclusion Ultrasound-guided continuous ESPB could significantly reduce perioperative opioid consumption in VATS and improve postoperative rehabilitation. However, these effects were inferior to those provided by TEA.

Trial registration The present study was prospectively registered at http://www.chictr.org/cn /(Registration number: ChiCTR1900023050); Registration date: May 8,2019

Introduction

Over the past decades, video-assisted thoracoscopic surgery (VATS) has become the most widely used surgical technique for managing primary lung cancer[1]. Compared with thoracotomy, VATS is considered to be associated with a shorter convalescence period, less pain, and better survival rates.[2] However, some patients still suffer from moderate-to-severe acute pain after VATS, particularly within 24h postoperatively.[3–5]

There are many modalities to alleviate post-thoracic surgery pain, ranging from various medications for patient-controlled analgesia to diverse regional analgesic methods[6]. Thoracic epidural anaesthesia (TEA) remains the “gold standard” for intraoperative analgesia and management of acute pain after thoracic surgery.[7, 8] In terms of pain relief, thoracic paravertebral block (PVB) is comparable to TEA, which is widely applied in thoracic surgery[9]. However, TEA is more invasive and can lead to devastating complications; moreover, TEA cannot be used in patients with severe spinal deformities who are anticoagulated or receiving anticoagulation treatment.[10–13] In addition, PVB is not widely used because it requires multiple injections and carries a risk of complications.[14]

In 2016, Forero et al. first described the erector spinae plane block (ESPB), which is a new technique representative of indirect PVB methods[15]. Since then, many studies have reported that ESPB is safe and easy to use. In ESPB, local anesthetics are injected into the fascial plane, deep into the erector spinae muscle, which is distant from the pleura and neuraxial structures. Through drugs penetrating intertransverse connective tissues, ESPB not only affects the ventral rami and dorsal side of the spinal nerve in the paravertebral space, but also the lateral cutaneous branches of the intercostal nerves [14, 15]. It has been widely reported that ESPB can provide effective analgesia in the thoracoabdominal region, in cardiothoracic surgery, breast surgery, and laparoscopic cholecystectomy [16, 17], and lengthen the duration of regional anaesthesia. A block can be administered continually with the help of a catheter, which can provide better postoperative analgesia and can be an alternative to TEA for pain management.[18–21] However, these data are mainly from case reports, and there is a paucity of research on randomized post-VATS ESPB studies. Therefore, prospective and randomized studies comparing the benefits of ESPB and traditional anaesthesia and analgesic regimens (such as general anesthesia with or without TEA) are needed. Moreover, besides pain, other debilitating side effects may also affect the patient’s recovery experience, and whether ESPB could improve postoperative rehabilitation is still unclear.

The present study was designed to determine whether ultrasound-guided continuous ESPB has an effect on opioid consumption and postoperative rehabilitation, as compared with general anaesthesia with or without TEA.

Methods

This study was approved by the Institutional Review Board of Zhongshan Hospital, Fudan University (B2019-074R)) and written informed consent was obtained from all subjects participating in the trial. The trial was registered prospectively prior to patient enrollment at http://www.chictr.org/cn/(registration number: ChiCTR1900023050, Principal investigator: Chao Liang, Date of registration: 08/05/2019). The study protocol was performed in accordance with the relevant guidelines and has been reported in line with Consolidated Standards of Reporting Trials (CONSORT) Guidelines.

Study Population

Patients 20–70 years of age, of American Society of Anesthesiologists physical status (ASA PS) 1 or 2, and diagnosed with solitary pulmonary nodules without chronic pain (with no pain medications routinely used) were deemed suitable to undergo 3-port single-intercostal VATS performed by surgeons. The exclusion criteria included pre-existing infection at the block site, history of chronic pain, significant coagulopathy, contraindication to techniques or drugs used in the protocol, and conversion to open thoracotomy.

Randomization And Patient Grouping

According to a computer-generated randomization list, patients were assigned in blocks of three, with a sealed envelope technique, to one of three groups: Group C (General anesthesia with patient-controlled intravenous analgesia [PCIA]), Group T (General anesthesia with patient-controlled epidural analgesia [PCEA]), or Group E (general anesthesia with continuous ESPB and PCIA).

Method Of Anesthesia And Analgesia

On arrival at the operating room, routine monitoring, including invasive blood pressure, pulse oxygen saturation (SpO₂), and electrocardiography, was performed. In group T, the patient was placed in a left lateral decubitus position, and a thoracic epidural catheter (19G; Pajunk GmbH Medizintechnologie, Germany) was inserted at the thoracic (T) T7 to T8 epidural space by an experienced anesthesiologist, before induction. In group E, before induction, the patient was placed in a left lateral decubitus position, and a high-frequency linear ultrasound transducer was placed in a longitudinal orientation, 3 cm lateral to the T5 spinous process. Three muscles superficial to the hyperechoic transverse process shadow were identified as follows: trapezius, rhomboid major, and erector spinae. Under ultrasound guidance, an 8-cm 22-gauge block needle was inserted in-plane in a caudad-to-cephalad direction, until the tip was laid on the surface of the transverse process. The correct needle tip position was confirmed by visualizing the linear fluid spread that separated the erector spinae muscle from the transverse process. Then, 30 mL of 0.375% ropivacaine was injected deep into the erector spinae muscle, and a thoracic epidural catheter was subsequently inserted. After confirmation and assessment of the sensory block to pinprick, general anesthesia induction was initiated.

General anesthesia was induced with propofol Target controlled infusion(TCI) (target plasma concentration was set at 4.0 µg ml^− 1), remifentanil (0.2 µg kg^− 1min^− 1), sufentanil (0.2 µg kg^− 1), and rocuronium bromide (0.6 mg kg^− 1). Patients were intubated using a double-lumen tube to achieve lung isolation, and then correct positioning was confirmed by fibreoptic bronchoscopy. After induction, ropivacaine (0.1875%, 5 mL) was injected into the epidural space of the patients in group T every 5 minutes, a total of 3 times, and ropivacaine (0.1875%, 5 mL) was injected into the epidural space every hour during surgery. One-lung ventilation was initiated when the operation was started. Anaesthesia was maintained with sevoflurane (0.8 MAC). During the surgical procedure, 5 µg of sufentanil was administered intravenously in both groups to maintain the systolic BP changes within 20% of the baseline. This dose was repeated every 10 min until the blood pressure returned to the required limits. Rocuronium was administered as required.

All patients in three groups using the same electronic analgesia pump (AM380; ACE Medical Co. Ltd, Gyeoggi, Korea). In group C, the drugs used for PCIA were sufentanil (1µg/kg) and ramosetron (0.6 mg), which were diluted in 0.9% normal saline to a final volume of 250 mL. The analgesia pump settings were as follows: background dose, 0 mL/h; self-controlled additional dose, 4 mL/time; and lockout time, 6 minutes. In group T, the drugs administered for PCEA were ropivacaine (0.12%) and sufentanyl (0.6 µg/mL), diluted in 0.9% normal saline to a final volume of 250 mL. The analgesia pump settings were as follows: background dose, 3 mL/h; self-controlled additional dose, 4 mL/time; and lockout time, 10 minutes. In group E, the drugs administered for continuous ESPB analgesia was ropivacaine (0.2%) diluted in 0.9% normal saline to a final volume of 250 mL. The analgesia pump settings were as follows: background dose, 7 mL/h; self-controlled additional dose, 0 mL/time; and lockout time, 40 minutes. A PCIA pump (with settings same as for group C) was also used in group E to evaluate postoperative sufentanil consumption.

Intraoperative and postoperative sufentanil consumption in each group was recorded. During the preoperative preparation, patients were educated to evaluate their pain using the visual analog scale (VAS) with scores ranging from 0 to 10 (0 = no pain, 10 = worst pain), VAS scores at rest and during coughing immediately out of post-anaesthesia care unit (PACU), at postoperative 6h, 12h, and 24h, were recorded. Before the day of surgery, patients were asked by the investigators to complete the Quality of Recovery-15 (QoR-15) questionnaire as a measure of baseline (relatively healthy) status. They were then asked to again fill the questionnaire 24h postoperatively. Opioid-related adverse events after the operation, such as nausea and vomiting, dizziness, hypotension, pruritus, and respiratory symptoms, were also recorded.

Statistical analysis

Results

A total of 120 patients participated in present study. Forty subjects were initially randomized into each group (Figure.1). The subject characteristics or surgical characteristics were shown in Table 1.

The intraoperative sufentanil consumption in groups T and E was significantly lower than that of group C (both P < 0.001), and no significant differences in intraoperative sufentanil consumption were found between groups T and E. Moreover, the postoperative sufentanil consumption in group E was also significantly less than that in group C (P = 0.001) (Fig. 2). Compared with group C, the VAS scores at rest or during coughing, across different study times, were all significantly lower in group T (P < 0.05) (Fig. 3). However, the VAS scores in group E were lower than those of group C only at rest at postoperative 6h and 12h (P < 0.05). Compared with group T, the VAS scores of Group E were significantly higher in all the study times (P < 0.05) (Fig. 3).

The preoperative baseline values of QoR-15 were comparable in two groups, while the postoperative QoR-15 values of groups T and E were significantly higher than those of group C (P < 0.001 and P = 0.004). However, the postoperative QoR-15 value of group E was lower than that of group T (P = 0.0005) (Fig. 4). Compared with groups C and T, the incidence of postoperative nausea and vomiting in group E was lower, but the difference was not statistically significant (both P = 0.154). In addition, TEA significantly increased the incidence of pruritus compared with groups C and E (both P = 0.005) (Table 2).

Discussion

Many reports have demonstrated effective analgesia using ESPB for the management of postoperative pain in patients undergoing VATS[22]; however, few studies have comprehensively compared the efficacy of ESPB with traditional anaesthesia and analgesic regimens. Herein, we investigated whether ultrasound-guided continuous ESPB has an effect on opioid consumption and postoperative rehabilitation. The results showed that, compared with general anaesthesia with PCIA, continuous ESPB significantly reduced perioperative opioid consumption and improved postoperative rehabilitation in patients undergoing VATS. However, the analgesic and rehabilitation improvement effects of ESPB were inferior to those provided by TEA.

By using ultrasound, regional nerve blocks can be performed precisely with minimal risk. Therefore, there has been a resurgence of interest in nerve blocks that were once considered difficult to perform, for example, paravertebral block, which has been demonstrated to have similar efficacy as epidural analgesia[23, 24]. As a novel technique that may have the potential to add to the current modalities used for analgesia[15], ESPB can cause somatic, visceral, and sympathetic nerve block at multiple levels and might improve analgesia and lung function after VATS. However, our results showed that although continuous ESPB provided better analgesia than PCIA postoperatively, the average VAS score in group E was higher than that of group T, which indicated that the effects of continuous ESPB for postoperative analgesia were inferior to those of continuous TEA. This may be due to the limited penetration of local anesthetics from the fascial plane into the pleura and neuraxial structures. In our study, after a single shot for ESPB, instead of an intermittent bolus, a continuous infusion regimen of local anaesthetics was implemented. Therefore, an effective pressure gradient between the injected fascial plane and the lamina of thoracic vertebrae could not be established, which significantly impacts the postoperative analgesic effects of continuous ESPB. This may explain why the VAS scores in group E were lower than those of group C only at rest at postoperative 6h and 12h, but not at 24h. Thus, the analgesic effects in group E might have been mainly produced by the first single shot of local anaesthetics before anaesthesia induction. This speculation was also supported by the evidence that the time for the first required analgesia was 6–7 hours postoperatively in patients with ESPB undergoing VATS[25]. Therefore, applying an intermittent bolus protocol in ESPB for postoperative analgesia seems more suitable.[20] However, the superiority of each of the administration regimes is yet unclear.[26]A recent pooled review of all published studies regarding ESPB reported 80% single-shot techniques, followed by continuous infusions (8%) and intermittent boluses (12%)[22], and further studies are needed before a more reasonable administration regimen is determined.

Recent studies have compared ESPB and serratus anterior plane block (SPB) for the management of postoperative pain following VATS[25, 27]. In these studies, the pain severity, time for first postoperative analgesia requirement, and intraoperative and postoperative analgesic requirements were primary outcomes, and a trigger point was set for anaesthesiologists to intervene with analgesia in the postoperative period, with a VRS score of > 2 or 4 as the threshold. However, we only calculated the total opioid consumption since each patient in groups E and C received a PCIA analgesic regimen, with the background dose of PCIA pump set at 0 mL/h, and all patients in groups C and E were well educated preoperatively on how to correct the PCIA. Moreover, in our pilot study, we found that patients who received PCEA had excellent analgesic effects; thus, we did not apply an additional PCIA pump in patients of group E.

Although reduction of pain is important, it may not be perceived by the patient as a better recovery experience if they experienced other debilitating side effects. The QoR-15 is a multidimensional patient-reported instrument used for functional recovery assessment[28]. The main domains of QoR-15 include pain, physical comfort, physical independence, and psychological and emotional states. The questions of these domains use a ten-point scale ranging from 0 to 10, with scoring reversed for negative questions, and the sum of the individual domains generates the global score (0, worst recovery; 150, optimal recovery). A previous study has reported that ESPB can provide superior quality of recovery at 24 h, better analgesia, and lower morbidity after minimally invasive thoracic surgery.[27] For a more accurate evaluation of patient recovery, a baseline QoR-15 value was collected for all enrolled patients. Given the patient factors such as fatigue and anxiety related to impending surgery, the ability of QoR-15 in the immediate preoperative period to provide an accurate baseline has been questioned[29]. However, no significant differences were found between the groups in the present study. Compared with general anaesthesia with PCIA, the postoperative QoR-15 value was significantly higher in patients who received continuous TEA and ESPB analgesia. Since a change in the score of 8 or more signifies a clinically important improvement or deterioration, the data from the present study may reaffirm the important role played by regional analgesia in improving postoperative rehabilitation after VATS. However, the postoperative QoR-15 value of group E was lower than that of group T, which may indicate that the rehabilitation improvement effects of ESPB are inferior to those provided by TEA.

In the present study, a lower incidence of PONV was found in the TEA analgesia group, which may indicate lower opioid consumption and a lower incidence of PONV. However, a higher incidence of pruritus in the TEA analgesia group than that in the EPSB and PCIA groups may attribute to the epidural use of sufentanil, which is consistent with the results from previous studies[30, 31]. There are some limitations to the present study. First, we investigated the analgesic effects of ESPB on three-port VATS, while one- or two-port VATS are also prevalent in these years; therefore, a large study involving more types of VATS is needed to investigate the analgesic effects of ESPB on VATS. However, recently published expert opinion suggests that the pain levels are similar to those of patients who undergo VATS[27]. Second, our study did not investigate the incidence of postoperative complications, such as pneumonia, surgical site infection, and acute kidney injury; it has been reported that regional anaesthesia may be associated with a lower incidence of these complications[27]. Third, we only collected analgesia and rehabilitation information until postoperative 24h, since acute postoperative pain is a powerful predictor of post-thoracotomy pain syndrome (PTPS)[32]. We plan to investigate the effects of continuous ESPB on long-term pain, such as on postoperative 48h or 72h, and even on the incidence of PTPS, in a future study.

Conclusion

In conclusion, compared to general anesthesia with PCIA, general anaesthesia combined with continuous ESPB brought about a dramatic reduction in opioid consumption in VATS. Moreover, the ESPB improved postoperative rehabilitation. However, the analgesic effects and improvement of rehabilitation due to ESPB was inferior to that provided by TEA. These findings may provide some information or insights for clinical work and future studies in this area.

Abbreviations

ESPB: erector spinae plane block, VATS:video-assisted thoracic surgery, PCIA: patient-controlled intravenous analgesia, PCEA:patient-controlled epidural analgesia, TEA:Thoracic epidural anaesthesia, PVB:thoracic paravertebral block, SpO₂: pulse oxygen saturation, TCI:Target controlled infusion, VAS:visual analog scale, PACU: post-anaesthesia care unit, QoR-15:Quality of Recovery-15, ANOVA:one-way analysis of variance

Declarations

Acknowledgements

Not applicable.

Funding

This research was supported by  

Availability of data and materials

Reasonable requests for access to the datasets used and/or analysed during this study can be made to the corresponding author

Authors’ contributions

S.Z and D.Z undertook all analyses, collated and analysed the data, and drafted the paper. X.D.H. and M.L.S undertook data analyses under the supervision of C.L and J.C. C.H.M contributed to study design and ethics committee submission. All authors approved the final manuscript.

Ethics approval and consent to participate

This study was approved (IRB:B2018-314R) by the Ethics Committee of Zhongshan Hospital, Fudan University on Dec 4, 2018. All of the participants gave their written, informed consent to participate in the study.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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