Thoracic paravertebral block (PVB) is an effective regional block for pain control after breast surgery. However, accidentally puncturing adjacent vital structures may cause undesirable complications. Erector spinae plane block (ESPB) has been considered a safer proxy of PVB for beginners. This study aimed to evaluate the analgesic effects of ultrasound-guidance PVB and ESPB after breast surgery.
This randomized control trial was conducted in patients who underwent mastectomy. Forty-four females were randomly allocated into PVB group or ESPB group. All patients received a block with 20 ml of 0.5% levobupivacaine before general anesthesia. The primary outcome was the 24-h postoperative morphine requirements. The other outcomes of interest were postoperative pain scores, time to first analgesic request, dermatome of sensory blockade, block-related complications, and opioid adverse events.
The 24-h morphine requirements were significantly lower in PVB compared to the ESPB group (3.5 ± 3.3 vs. 8.6 ± 3.8 mg, P < 0.001). The overall pain scores were also lower in the PVB group (P < 0.001). Only 14 patients in the PVB group requested additional morphine, whereas all patients in the ESPB group requested it (P = 0.004). The dermatome of sensory blockade was wider in the PVB group (7 vs. 4 levels, P = 0.019). No serious complications occurred in either group.
Compared to ESPB, PVB provided lower postoperative opioid requirements, lower pain scores, and wider sensory blockade after mastectomy.
Breast surgery is one of the primary treatment options for breast cancer, the most common malignancy in female, accounting for 25% of all cancers in women [
This controlled, randomized, double-blinded study was conducted in a university hospital. It was approved by the Institutional Ethics committee (no. HE62148) and had been registered before enrollment started (TCTR20200105003). After obtaining written informed consent from all participants, we enrolled patients who underwent unilateral mastectomy from January to August 2020. Patients aged 18–75 years with the American Society of Anesthesiologist physical status I–III were included. Patients with the following conditions were excluded: (1) pregnancy or lactation; (2) coagulation disorders; (3) skin lesion at the block site; (4) allergy to study drugs; (5) inability to cooperate; and (6) body mass index (BMI) greater than 35 kg/m2. Patients were randomly allocated (allocation ratio 1:1) into two groups: PVB group and ESPB group using computer-generated random numbers (
The self-reported pain assessment using the numeric rating scale (NRS), ranging from 0 = no pain to 10 = maximum pain, was instructed on the day before surgery. On the day of surgery, patients received oral acetaminophen 1,000 mg as pre-emptive analgesia 2 h before the operation. The random sequence numbers contained in the envelope were revealed in the procedural area by an anesthesiologist who was not involved in data collection. Each patient received a block on their back under sedation, and the data recorder was not present at the block area. Thus, they were blinded to the group allocated.
In the procedural area, the patient was connected to standard monitoring equipment (electrocardiogram, non-invasive blood pressure, and pulse oximetry), then placed in the lateral position with the affected side up, followed by intravenous (IV) fentanyl 50 µg and IV midazolam 1–2 mg for sedation. An experienced anesthesiologist performed all the blocks under ultrasound (US) guidance (SONIMAGE HS1, Konica Minolta, Japan) using a high-frequency (15–6 MHz) linear transducer. For all patients, 20 ml of 0.5% levobupivacaine and a 22 G-80 mm nerve block needle were used.
The PVB was performed using the intercostal approach [
Regarding the ESPB, the 4th rib was first identified with the same prior steps. Then the transducer was moved medially to identify the tip of the TP and the three back muscles (trapezius, rhomboid major, and erector spinae muscle; ESM). Then the needle was advanced with an in-plane approach from caudad to cephalad until its tip contacted the TP (
All patients underwent the same institutionally standardized operation and the same general anesthesia protocol. Anesthesia was induced with IV propofol 2–3 mg/kg and IV fentanyl 1.5–2 µg/kg. Tracheal intubation was facilitated with IV cisatracurium 0.1–0.2 mg/kg. For maintenance of anesthesia, patients received a mixture of air-oxygen (FiO2 0.4) and sevoflurane to keep the bispectral index between 40–60. In addition, intraoperative IV fentanyl could be administered in increments of 25 µg at the discretion of the blinded anesthesia team to maintain the hemodynamic parameters within 20% of baseline.
All patients received IV dexamethasone 8 mg and IV ondansetron 4 mg according to the institutional guidelines for postoperative nausea and vomiting (PONV) prophylaxis. At the end of the surgery, IV morphine (3 mg) was administered, except for those who were over 70 years of age, in which case 2 mg would be given. In addition, when the operation was finished, IV neostigmine 0.05 mg/kg and atropine 0.02 mg/kg were given for reversal of neuromuscular blockade. Patients were extubated according to the institutional protocol.
Patients were transferred to the post-anesthetic care unit (PACU) and cared for by a nurse blinded to their group allocation. According to our PACU protocol, patients received IV morphine 3 mg boluses whenever their NRS was greater than 3. The total morphine consumption in PACU was recorded. The same pain management protocol was applied in the ward, including oral acetaminophen of 1,000 mg every 6 h and IV morphine 2 mg boluses on-demand or whenever their NRS was greater than 3 for rescue analgesia.
The primary outcome was postoperative morphine requirements in the first 24 h after surgery. Secondary outcomes included morphine requirements in the first 48 h after surgery, the number of patients requiring rescue morphine, the frequency of rescue morphine requirements, time to first morphine request, NRS both at rest and on movement at PACU, and at 6, 12, 24, and 48 h postoperatively, dermatome of sensory blockade, and patient satisfaction (assessed by a 5-point scale from 0 = very dissatisfied to 4 = very satisfied). Block-related complications and adverse events such as pneumothorax, local anaesthetic systemic toxicity, respiratory depression (respiratory rate < 8 times/min), oversedation (Ramsay scale > level 4), and moderate to severe PONV (nausea or vomit that requires treatment and beyond) were also recorded.
Sample size was calculated using the program on the website (
Statistical analyses were performed using STATA version 10.1 (StataCorp LP, USA). Normality of data distribution was tested by the Shapiro–Wilk test. Continuous variables were reported as mean ± SD or median (1Q, 3Q). Categorical variables were presented as absolute numbers and percentages. Normally distributed continuous variables, including age, weight, and BMI were compared using independent Student’s
Fifty patients met the eligibility criteria, three refused to participate, and three others did not meet the inclusion criteria. Thus, 44 patients were enrolled and randomly divided into two groups (22 for each). The blocks were all successful, and all the participants were followed up and assessed on an intention-to-treat basis (
In terms of pain score, NRS at rest and on movement at PACU were significantly lower in the PVB group (P = 0.002 and < 0.001, respectively). Moreover, the overall NRS was also lower in the PVB group (P < 0.001) (
This randomized double-blind control trial (RCT) compared the analgesic effects after mastectomy between PVB and ESPB. Regarding the PVB group in this study, patients required lower postoperative opioids, had lower postoperative pain score, and had wider dermatome of sensory blockade compared to the ESPB group. Also, fewer patients in the PVB group required rescue morphine, and required it less frequently, compared to the ESPB group.
To date, trials that compared the analgesic efficacy between PVB and ESPB after breast surgery are sparse [
These findings contrast with our study, which suggests that PVB had superior analgesia over ESPB. The reason for this could be that we observed a wider dermatome of sensory blockade (7 vs. 4 levels) in the PVB group and a higher blockade percentage. In addition, intense blockade of over 80% at the T3–T6 dermatomes has occurred only in the PVB group, which was necessary for breast surgery analgesia that did not involve the axillary region, such as simple mastectomy, which was the majority of the cases in our study [
The precise sensory blockade provided by PVB in this study also resulted in lower postoperative pain scores and morphine consumptions, as well as lower requirements and frequency of rescue morphine. According to Swisher et al. [
PVB is an RA technique of injecting LA into the PVS, allowing direct contact with the proximal spinal nerves and rami communicant of sympathetic fibers, resulting in a precise ipsilateral somatic and sympathetic blockade. A relatively new technique, ESPB was first introduced as a regional block to treat thoracic neuropathic and acute pain [
How LA spread in cadavers may not represent the proper LA spread in living humans because negative intrathoracic pressure during respiration, ESM contraction, and patient positioning can all enhance LA shift towards the PVS. Thus, examining the contrast dye with X-ray or magnetic resonance imaging (MRI) is more appropriate for evaluating the spread in humans [
In addition, a recent volunteer study reported a widespread area of decreased sensory sensation in the posterior thorax without any evidence of sensory blockade of the anterior and lateral chest walls following the ESPB with a 20 ml injection of 0.5% ropivacaine. As a result, only the dorsal rami of the spinal nerve were assumed to have been blocked [
In our study, a single-level injection of PVB at T4 was performed, and with the same technique and volume of LA, we found a wide sensory blockade, similar to a previous study (6 dermatomes, range, 5–6) [
The incidence of moderate to severe PONV was higher in the ESPB group but not significantly different. This might be an effect of our PONV prophylaxis regimen, which was administered to all participants. Pneumothorax did not occur in our study, similar to previous studies, which might be because all blocks were performed by the expert and under US-guidance [
Notably, even though postoperative morphine consumption and pain score are important considering factors when selecting an appropriate block technique, there remain essential elements that must be included in the decision-making process, such as the clinician's proficiency, the technical difficulty, the invasiveness, the pain intensity created by the procedure, and the patient's pain experience and expectations [
The present study had some limitations. First, we did not apply a sham or no-block group in our protocol as there was adequate evidence to support the analgesic effects of these two regional blocks without the need to compare them with a control group. Second, the evaluation period of the sensory blockade in this study might be relatively short for the demonstration of actual blockade in fascia plane blocks like ESPB. We chose 15 min after block to evaluate the sensory blockade as we were concerned about the busy operating room schedule. Ultimately, we believe that this decision did not interfere with our primary outcome, which was the morphine consumption within 24 h. Lastly, our participants were not followed up long-term, hence we could not assess the impact of the blocks on long-term outcomes such as post-surgical pain syndrome or the recurrent cancer rate.
In conclusion, compared to ESPB, PVB provided lower postoperative opioid requirements and decreased postoperative pain score with broader dermatome of sensory blockade after mastectomy surgery.
This study was granted by Faculty of Medicine, Khon Kaen University, Thailand (Grant Number IN: 63240).
No potential conflict of interest relevant to this article was reported.
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Conceptualization: Aumjit Wittayapairoj, Nattanan Sinthuchao. Data curation: Aumjit Wittayapairoj, Nattanan Sinthuchao, Ongart Somintara, Viriya Thincheelong, Wilawan Somdee. Formal analysis: Aumjit Wittayapairoj, Ongart Somintara. Funding acquisition: Aumjit Wittayapairoj. Methodology: Aumjit Wittayapairoj, Nattanan Sinthuchao. Project administration: Aumjit Wittayapairoj, Nattanan Sinthuchao, Ongart Somintara. Writing - original draft: Aumjit Wittayapairoj, Nattanan Sinthuchao. Writing - review & editing: Aumjit Wittayapairoj, Nattanan Sinthuchao, Ongart Somintara. Investigation: Aumjit Wittayapairoj, Nattanan Sinthuchao, Viriya Thincheelong, Wilawan Somdee. Resources: Viriya Thincheelong, Wilawan Somdee. Supervision: Aumjit Wittayapairoj. Validation: Aumjit Wittayapairoj, Ongart Somintara.
We would like to thank you, Dr. Atipong Pathanasethpong, for editing this manuscript's English language.
Ultrasound images of PVB (A) and ESPB (B). PVB: thoracic paravertebral block, ESPB: erector spinae plane block, ESM: erector spinae muscle, IIM: internal intercostal membrane, PVS: paravertebral space (a wedge shape), TP: transverse process, white dash-line represented needle trajectory.
CONSORT flow diagram for the study. CONSORT: Consolidated Standards for Reporting of Trials, PVB: thoracic paravertebral block, ESPB: erector spinae plane block.
Dermatome of sensory blockade following PVB and ESPB. PVB: thoracic paravertebral block, ESPB: erector spinae plane block, T: thoracic level.
Demographic and Operative Data
Variable | PVB (n = 22) | ESPB (n = 22) | P value |
---|---|---|---|
Female | 22 (100) | 22 (100) | NA |
Age (yr) | 54.2 ± 9.8 | 56.1 ± 9.1 | 0.526 |
Weight (kg) | 59.7 ± 8.9 | 61.1 ± 10.5 | 0.645 |
Body mass index (kg/m²) | 24.5 ± 3.4 | 24.3 ± 3.8 | 0.878 |
ASA PS (I/II) | 5 (22.7)/17 (77.3) | 4 (18.2)/18 (81.8) | < 0.999 |
Type of surgical procedure | 0.361 | ||
Simple mastectomy | 11 (50.0) | 14 (63.6) | |
Modified radical mastectomy | 11 (50.0) | 8 (36.4) | |
Operative time (min) | 181.6 ± 78.1 | 156.6 ± 56.0 | 0.228 |
Intraoperative blood loss (ml) | 59.3 ± 60.1 | 72.5 ± 68.6 | 0.318 |
Values are presented as mean ± SD or number (%). PVB: thoracic paravertebral block, ESPB: erector spinae plane block, ASA PS: American Society of Anesthesiologists physical status, NA: not applicable. Independent Student’s
Perioperative Opioid Consumption
Variable | PVB (n = 22) | ESPB (n = 22) | MD (95% CI) | P value |
---|---|---|---|---|
Intraoperative fentanyl consumption (µg) | 158.0 ± 49.0 | 177.3 ± 51.7 | –19.3 (–49.9 to 11.3) | 0.212 |
Total morphine consumption in 24 h (mg) | 3.5 ± 3.3 | 8.6 ± 3.8 | –5.1 (–7.3 to –2.9) | < 0.001 |
Time to first analgesic request (min) | 209.1 ± 61.1 | 197.4 ± 49.5 | 11.8 (–25.9 to 49.4) | 0.532 |
Number of patients requiring rescue morphine | 14 (63.6) | 22 (100.0) | NA | 0.004 |
Frequency of rescue morphine requirements (time) | 1 (0, 2) | 3 (2, 4) | NA | < 0.001 |
Values are presented as mean ± SD, number (%), or median (1Q, 3Q). PVB: thoracic paravertebral block, ESPB: erector spinae plane block, MD: mean difference, CI: confidence interval, NA: not applicable. Mann–Whitney
P < 0.05 was considered statistically significant.
Postoperative Pain Score
Variable | PVB (n= 22) | ESPB (n = 22) | MD (95% CI) | P value |
---|---|---|---|---|
Overall pain score at rest | 1.68 (0.74 to 2.63) | < 0.001 |
||
At PACU | 2.73 ± 1.78 | 4.41 ± 1.44 | 1.68 (0.44 to 2.92) | 0.002 |
At 6 h | 1.32 ± 1.17 | 2.09 ± 1.72 | 0.77 (–0.35 to 1.90) | 0.387 |
At 12 h | 0.68 ± 0.95 | 1.23 ± 1.11 | 0.55 (–0.25 to 1.34) | 0.379 |
At 24 h | 0.50 ± 0.86 | 0.68 ± 0.95 | 0.18 (–0.51 to 0.88) | > 0.999 |
At 48 h | 0.41 ± 0.73 | 0.59 ± 0.91 | 0.18 (–0.45 to 0.82) | > 0.999 |
Overall pain score on movement | 2.50 (1.28 to 3.72) | < 0.001 |
||
At PACU | 3.55 ± 2.22 | 6.05 ± 1.94 | 2.50 (0.90 to 4.10) | < 0.001 |
At 6 h | 2.91 ± 1.27 | 3.41 ± 1.18 | 0.50 (–0.44 to 1.44) | 0.856 |
At 12 h | 2.50 ± 1.10 | 2.64 ± 1.29 | 0.14 (–0.79 to 1.06) | > 0.999 |
At 24 h | 2.09 ± 1.23 | 2.09 ± 1.02 | 0.00 (–0.87 to 0.87) | > 0.999 |
At 48 h | 1.73 ± 1.24 | 1.86 ± 1.36 | 0.14 (–0.86 to 1.13) | > 0.999 |
Values are presented as mean ± SD. PVB: thoracic paravertebral block, ESPB: erector spinae plane block, MD: mean difference, CI: confidence interval, PACU: post anesthesia care unit.
P < 0.05 was considered statistically significant.
Analysed by generalized estimating equations model.
Compared pain score between ESPB vs. PVB at PACU, 6, 12, 24, and 48 h.
Dermatome of Sensory Blockade, Adverse Events, Complications and Patient Satisfaction
Variable | PVB (n = 22) | ESPB (n = 22) | P value |
---|---|---|---|
Dermatome of sensory blockade (levels) | 7 (5, 8) | 4 (1, 7) | 0.019 |
Adverse events and complications | |||
Moderate to severe PONV | 0 | 3 (13.6) | 0.351 |
Oversedation | 0 | 0 | NA |
Respiratory depression | 0 | 0 | NA |
Local anaesthetic systemic toxicity | 0 | 0 | NA |
Pneumothorax | 0 | 0 | NA |
Patient satisfaction | 0.531 | ||
Vary satisfied | 15 (68.2) | 13 (59.1) | |
Satisfied | 7 (31.8) | 9 (40.9) |
Values are presented as median (1Q, 3Q) or number (%). PVB: thoracic paravertebral block, ESPB: erector spinae plane block, PONV: postoperative nausea and vomiting, NA: not applicable. Mann–Whitney
P < 0.05 was considered statistically significant.