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Analgesic Benefit of Pectoral Nerve Block II Blockade for Open Subpectoral Biceps Tenodesis: A Randomized, Prospective, Double-Blinded, Controlled Trial

Reynolds, J. Wells MD*; Henshaw, Daryl S. MD*; Jaffe, J. Douglas DO*; Dobson, Sean W. MD, PhD*; Edwards, Christopher J. MD*; Turner, James D. MD*; Weller, Robert S. MD*; Graves, Benjamin R. MD; Freehill, Michael T. MD

doi: 10.1213/ANE.0000000000004233
Regional Anesthesia and Acute Pain Medicine: Original Clinical Research Report
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BACKGROUND: Axillary pain is common after arthroscopic shoulder surgery with an open subpectoral biceps tenodesis. We hypothesized that adding a pectoral nerve block II (Pecs II) to an interscalene block (ISB) would improve postoperative analgesia in this surgical population.

METHODS: Forty patients were enrolled in this prospective, randomized, observer and patient-blinded, single-institution trial. All 40 patients received a single-injection ISB with 20 mL of 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine. The intervention arm (ISB + Pecs II) consisted of 20 patients who also received a Pecs II block using 30 mL of 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine. The 20 control group patients (ISB) received a sham Pecs II block. The primary outcome was postoperative pain scores at 6 hours using the numeric rating scale (NRS; range, 0–10) and was analyzed using the Mann-Whitney U test. Secondary outcomes included the presence of axillary pain at 6 hours, the need for postanesthesia care unit (PACU) opioids, PACU length of stay (LOS) (minutes), NRS pain scores at 24 hours, cumulative opioid usage postdischarge through 24 hours, the presence of nausea or vomiting during the first 24 hours, and Pecs II block duration (in hours, based on time to onset of axillary pain). Data were analyzed using a modified intention-to-treat (ITT) methodology.

RESULTS: Pain scores (NRS, 0–10) at 6 hours differed significantly between groups: ISB 3.0 (0.25–5.0) (1.7–4.3) versus ISB + Pecs II 0.0 (0–2.0) (0.0–1.1) (median [IQR] [95% CI]); P = .026. Hodges–Lehmann estimator of the difference was 2.0 (95% CI, 0.0–4.0). Fewer patients in the ISB + Pecs II group reported axillary pain at 6 hours and fewer required opioids in the PACU. There were no differences in any of the remaining secondary outcomes.

CONCLUSIONS: The addition of a Pecs II block to an ISB for patients undergoing arthroscopic shoulder surgery with an open subpectoral biceps tenodesis significantly improved postoperative analgesia and reduced the need for opioids in the PACU.

From the Departments of *Anesthesiology

Orthopaedic Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina

Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan.

Published ahead of print 11 April 2019.

Accepted for publication April 11, 2019.

Funding: Institutional and/or departmental.

Conflicts of Interest: See Disclosures at the end of the article.

Prior presentations at the Wake Forest School of Medicine, Department of Anesthesiology Research Day, Poster Session, Winston-Salem, NC, May 15, 2018.

Clinical Trial Registry Number: NCT02741713 at ClinicalTrials.org.

Reprints will not be available from the authors.

Address correspondence to J. Wells Reynolds, MD, Department of Anesthesiology, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157. Address e-mail to jreynold@wakehealth.edu.

The interscalene nerve block (ISB) has been a highly successful modality for providing postoperative analgesia after both arthroscopic and open shoulder surgeries for decades.1 Even when low volumes and dilute local anesthetic concentrations are utilized, an ISB has been shown to provide effective analgesia for outpatient arthroscopic shoulder procedures as demonstrated by lower pain scores and a reduced need for opioids.2–4 An ISB anesthetizes both the upper and middle trunks of the brachial plexus, resulting in coverage of the various nerves (subscapular nerve, axillary nerve, suprascapular nerve, and the lateral pectoral nerve) that innervate the shoulder joint and the surrounding soft-tissue structures.5

Treatment of biceps tendon pathology may include a biceps tenodesis procedure, which can be performed via an intra-articular arthroscopic approach or an open subpectoral technique. The open approach requires an incision on the anteromedial proximal upper arm, centered over the inferior margin of the pectoralis major tendon, and adjacent to the axilla (Figure 1).

Figure 1.

Figure 1.

Surgeons at our institution noted frequent axillary pain complaints from patients who received an open subpectoral biceps tenodesis despite receiving a successful ISB. Anatomically, this makes sense given that an ISB does not provide analgesic coverage for the axilla or the medial proximal arm because it does not anesthetize the intercostal nerves, including the intercostobrachial nerve (T2). In addition, it also spares the lower trunk of the brachial plexus (C8-T1 nerve roots), which is the origin of the medial brachial cutaneous nerve and the medial pectoral nerve.

Pectoral nerve blocks (Pecs),6,7 first described by Raphael Blanco, have been shown to be beneficial for patients undergoing radical breast surgery, including lymph node dissection.8 The originally described Pecs I block involves placing local anesthetic between the pectoralis major and minor muscles to anesthetize the medial and lateral pectoral nerves.6 The Pecs II block adds a second injection between the pectoralis minor and serratus anterior muscles to anesthetize several contiguous intercostal nerves. Given the incisional location and reported axillary pain in patients undergoing a subpectoral biceps tenodesis surgery, as well as the expected anatomical coverage of the Pecs II block, this study was performed to evaluate the benefit of adding a Pecs II block to an ISB for patients undergoing a combined shoulder arthroscopy and an open subpectoral biceps tenodesis. The hypothesis was that the addition of a Pecs II block would reduce postoperative pain at 6 hours after block placement.

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METHODS

This prospective, randomized, observer and patient-blinded, single-institution trial was completed at Wake Forest Baptist Hospital and Davie County Medical Center, Wake Forest Baptist Health, Winston-Salem, NC, from May 2016 to June 2017 after Institutional Review Board (#00030173) approval. The trial was registered before patient enrollment at clinicaltrials.gov (NCT02741713; principal investigator: J.W.R.; date of registration: April 18, 2016). Enhancing the Quality and Transparency of Health Research Network (EQUATOR; Consolidated Standards of Reporting Trials [CONSORT] 2010) guidelines for research were followed. Written informed consent was obtained from all patients before enrollment. To be eligible, patients needed to be between the ages of 18 and 90 years and scheduled for elective shoulder arthroscopy with a planned open, subpectoral biceps tenodesis. Exclusion criteria consisted of concomitant acromion or clavicular surgery, existing neuropathy of the upper extremity, opioid use >40 mg of oxycodone equivalents daily, contraindications to phrenic nerve blockade, pregnancy, coagulopathy, allergy to amide local anesthetics, or morbid obesity that might impair pectoralis ultrasound imaging. Target enrollment was 40 patients, and computer-generated block randomization was performed. Group assignments were sealed in opaque envelopes before the initiation of the study and were opened immediately before each participant’s procedure. Patients were randomly assigned equally to either the intervention group (ISB + Pecs II) or the control group (ISB).

In the holding room, standard monitors were applied (electrocardiography [ECG], pulse oximetry, end-tidal carbon dioxide, and automated noninvasive blood pressure). A peripheral intravenous (IV) line was placed, and supplemental oxygen was administered. Procedural sedation (midazolam and fentanyl) was administered and titrated to an appropriate level of sedation for the procedure at the discretion of the procedural physician. Unless contraindicated, each patient received 650 mg of oral acetaminophen before block placement.

All 40 subjects received an ultrasound-guided ISB using 20 mL of 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine dosed at the upper trunk location near the C6 vertebral level, per standard clinical practice. The 20 patients randomly assigned to the ISB + Pecs II group also received a Pecs II block as described by Blanco with 0.25% bupivacaine with 1:400,000 epinephrine and 1:600,000 clonidine.3,4 For the Pecs II block, 20 mL was injected in the fascial plane between the pectoralis minor and serratus anterior muscles, while 10 mL was injected at the Pecs I location between the pectoralis major and minor muscles. The 20 patients randomly assigned to the ISB group received a sham Pecs II block. The sham block consisted of skin preparation, ultrasound scanning of the chest wall, and a local anesthetic skin wheal, all performed after sedation to preserve patient blinding. All blocks were performed by an upper-level resident or regional anesthesia fellow under direct supervision by 1 of the 6 members of the Regional Anesthesia & Acute Pain Management Section. A linear transducer (6–13 MHz; Fuji Sonosite, Bothell, WA) was utilized for all procedures.

After the completion of all nerve blocks, we attempted to assess block success at 15 and 30 minutes, as well as in the postanesthesia care unit (PACU) if needed. Utilizing a 25-gauge Whitacre needle, a blinded observer assessed cutaneous sensation over the deltoid region for the ISB and the anterior axillary line at the level of the nipple for the Pecs II block. Block success was assumed if there was either a decrease or complete absence of pinprick sensation at any time point using the following scale: 0 = full sensation, 1 = partial sensation, 2 = absence of sensation. The surgeon, block assessor, and data collector were all blinded to the treatment randomization.

All patients received general endotracheal anesthesia. Intraoperatively, the subpectoral incision was made approximately 3 cm in length with a 15-blade knife and was centered over the inferior border of the pectoralis major tendon after a patient-specific axillary skin crease. Arthroscopic portal sites were placed as per standard orthopedic practice. No local anesthetics were injected by the surgeon during the procedure. The operating room (OR) anesthesia team was instructed to avoid the administration of dexamethasone and ketamine, but otherwise the intraoperative anesthetic was not dictated by the study protocol and intraoperative fentanyl was administered by the anesthetist per routine clinical practice. In the PACU, rescue IV fentanyl and oral oxycodone were made available to the patients as rescue analgesics.

Outcome data were collected at both 6 and 24 hours after block placement. Depending on the patient’s clinical course, the 6-hour time point assessment occurred either in the PACU or postdischarge by phone. Given the outpatient nature of the surgery, all 24-hour assessments were performed by phone. The primary outcome was numeric rating scale (NRS; range: 0–10) resting pain scores at 6 hours. Secondary outcomes included the presence of axillary pain at 6 hours (binary outcome of yes or no), the need for PACU opioids (given at the discretion of PACU nursing staff based on patients reported NRS pain scores), overall PACU length of stay (LOS) (minutes), NRS resting pain scores at 24 hours, cumulative oral (PO) opioid usage after PACU discharge, and the presence of nausea or vomiting at any time postdischarge. In addition, if axillary pain was absent at 6 hours, but present at 24 hours, the reported onset time of axillary pain was recorded. All opioids were converted to oxycodone equivalents using oral morphine conversion factors.9 Preoperative benzodiazepine, acetaminophen, and opioid administrations were recorded, as were intraoperative and PACU opioids.

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Statistical Methodology

Continuous and categorical baseline characteristics were compared using Hedges standardized difference. The primary outcome was assessed using a Mann-Whitney U test and reported as median, interquartile range (IQR), and 95% confidence interval (CI) pain scores. The Hodges–Lehmann estimator and Cohen d were used to determine effect size estimates. Data distribution was assessed using the Kolmogorov–Smirnov test of normality examining kurtosis, skew, mean, median, and standard deviation (SD). Regarding the primary outcome, the ISB group data were compatible with normal distribution, while the Pecs II group was not normally distributed. Continuous secondary outcomes were approximately normally distributed, except for PACU fentanyl and oxycodone dose totals. Nonnormally distributed continuous secondary outcomes were assessed using the Mann-Whitney U test, while t tests were applied to normally distributed data. χ2 was used for the presence of axillary pain and PACU opioid utilization comparisons. Outcomes were assessed using a modified intention-to-treat (ITT) methodology because 3 of the subjects did not have the open surgical procedure. Pilot data from 5 subjects receiving only an ISB revealed NRS resting pain scores of 5.0 ± 1.4 (mean ± SD). Five pilot patients who received both an ISB and a Pecs II block had NRS pain scores of 0.0 ± 0.0. Using a 2-sided, 2-sample t test, an α value of .05, assuming a 2-point reduction in NRS resting pain scores, was clinically significant, and assuming a common SD of 1.4, a power analysis revealed that 12 subjects were needed per group for a power of 0.90 or 14 patients for a power of 0.95. We chose 20 subjects per arm to allow for potential dropout and an increased power. Statistics were completed using calculators found on http://www.socscistatistics.com.

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RESULTS

Forty-seven patients were screened. A total of 40 patients were ultimately consented and equally randomly assigned to either the ISB group (n = 20) or the ISB + Pecs II group (n = 20). Two patients in the ISB group and 1 patient in the ISB + Pecs II group were excluded from analysis due to a change in the planned intraoperative surgical technique. These 3 subjects did not have an open, subpectoral bicep tenodesis performed. The remaining 37 patients who underwent the surgical procedure of interest were included in the modified ITT analysis (Figure 2).

Figure 2.

Figure 2.

As shown in Table 1, the 2 groups had a slight imbalance regarding sex, body mass index (BMI), and baseline pain scores. There were no differences in the amounts of procedural sedation administered.

Table 1.

Table 1.

The primary outcome of resting NRS pain scores at 6 hours was significantly different between groups ISB 3.0 (0.25–5.0) (1.7–4.3) and ISB + Pecs II 0.0 (0–2.0) (0.0–1.1) (median [IQR] [95% CI]; P = .026; Figure 3). Hodges–Lehmann estimator of the difference was 2.0 (95% CI, 0.0–4.0). Cohen d effect size estimate equaled 0.75. All secondary outcomes are presented in Table 2. Of interest, 3 of 19 subjects (16%) in the ISB + Pecs II group reported having axillary pain at 6 hours, compared to 12 of 17 (71%) in the ISB group (P = .0008). In addition, the percentage of patients needing opioids in the PACU differed between groups (ISB + Pecs II 15.8% vs ISB 58.8%; P = .008). There were no differences in PACU LOS, NRS resting pain scores at 24 hours, cumulative opioids at 24-hour postdischarge, or the incidence of nausea or vomiting during the first 24 hours. Eight subjects in the ISB + Pecs II group were able to report a time to onset of axillary pain, which averaged 16.7 hours (14.1–19.3).

Table 2.

Table 2.

Figure 3.

Figure 3.

One patient in the ISB group deviated from protocol and received pregabalin 150 mg preoperatively, as well as IV ketamine and dexamethasone intraoperatively. Exclusion of this subject did not affect the primary outcome (P = .027). While most secondary outcomes were also unaffected, average PACU LOS decreased in the ISB group and this result became statistically significant with the ISB group having a shorter PACU stay, ISB + Pecs II 115 ± 40.5 vs ISB 91 ± 37.8 minutes (P = .0495).

Regarding block evaluations, 36 of 37 patients had ≥1 assessment. Seventeen of 18 ISB subjects were tested, and 16 of 17 (94%) had sensory change to pinprick. All 19 ISB + Pecs II subjects were examined, and 10 of 19 (53%) described blunted sensation. Five of the 9 subjects that reported normal sensation were limited to 15-minute (3/5) or 30-minute (2/5) assessments. There were no reported complications related to nerve block placement.

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DISCUSSION

This study demonstrates the utility of a Pecs II block for the reduction of postoperative pain associated with an open biceps tenodesis procedure with lower NRS resting pain scores 6-hour postblock placement in the ISB + Pecs II group. The number of patients that reported the presence of axillary pain at 6 hours was >4× lower in the ISB + Pecs II group, and the number of patients in the ISB + Pecs II group that required IV fentanyl for reported pain during their PACU stay was >3× lower compared to the control group. Considering that 59% of the patients in the ISB group received PACU opioids before their 6-hour assessment (compared to 16% in the ISB + Pecs II group), the pain score differential between groups may in fact be larger than what was found in this study.

There were no observed differences in 24-hour NRS resting pain scores. This is not entirely surprising because the onset of axillary pain averaged 16.7 hours post-Pecs II blockade and therefore block resolution would have occurred before the 24-hour assessment. A prior study using similar doses of perineural local anesthetic and adjuvant medications demonstrated that 75% of ISB patients regained sensation by 18 hours, further supporting the similar pain scores seen in our 2 study groups at 24 hours.10

Despite the reduced need for PACU opioids for the ISB + Pecs II patients, there was no difference in PACU LOS between treatment groups. There are many potential confounders that could have influenced discharge, including nursing decisions, movement from stage I to stage II of recovery, overall OR caseload, bed availability, and the availability of clinicians to sign patients out of the PACU. While it is not possible post hoc to determine the reasons for a prolonged PACU LOS, it is conceivable that any combination of these variables could have contributed to the lack of difference for the subjects in the ISB + Pecs II arm. For future studies, time to PACU discharge readiness might be a better end point.

Interestingly, while the majority of patients in the ISB group reported axillary pain at 6 hours (71%), it was not present in every patient. There could be several possible explanations for this finding. First, it is conceivable that in some patients, the ISB was performed more caudal than intended and therefore blockade of the lower trunk of the brachial plexus was achieved. This could explain the lack of axillary pain given that the medial brachial cutaneous nerve and the medial pectoral nerve both originate from the lower trunk of the brachial plexus. Interestingly, a prior study investigating whether an ISB performed at the lowest brachial plexus nerve roots could adequately block the hand and forearm revealed a success rate of 6%–33%.11 Second, it is possible that because of anatomic variability, the location of the incision for the open biceps tenodesis was actually in an area of the arm innervated by the axillary nerve, which would theoretically be covered by an ISB.

We chose NRS resting pain scores at 6 hours as the primary outcome to ensure that both groups of patients would have nerve blocks that were still active. Despite lower NRS pain scores at 6 hours in the ISB + Pecs II group, no difference was found between groups in regard to either cumulative opioids from the time of PACU discharge to 24 hours or the incidence of nausea/vomiting. It is important to recognize that the study was not powered to find a difference in any secondary outcome, including these. It is also possible that the ISB + Pecs II group experienced “rebound” axillary pain after the resolution of the Pecs II block and required higher or more frequent doses of self-administered opioids during the 16- to 24-hour time period compared to the ISB group that dosed their analgesics steadily over the first postoperative day. Future studies could evaluate the use of other local anesthetic additives, such as dexamethasone or buprenorphine, to extend the duration of Pecs II blockade and the impact this might have on this particular patient population.

This study has some limitations that warrant discussion. First, assessments for determining block success were challenging, and block success was not confirmed in all patients. This occurred in part because of the need for preoperative efficiency and the presence of a large dressing that made postoperative sensory testing challenging. It is also important to recognize that some studies involving “plane” blocks have shown significant variability in sensory testing results.12,13 This may be because the spread of local anesthetic injected into a fascial plane may be unpredictable and vary between patients, making sensory testing difficult. In our clinical experience, sensory changes for “plane” blocks, including Pecs II blockade, may take ≥30 minutes to develop. Due to the fact that we were not able to verify block success in all study patients, it is possible that some blocks were unsuccessful. However, because a modified ITT analysis was utilized, all patients would have been included in the analysis regardless of block success or failure.

We choose not to standardize either the intraoperative or PACU administration of opioids, other than to attempt to exclude the administration of dexamethasone, ketamine, and long-acting opioids. Our rationale for this was that these medications could have impacted reported pain scores at 6 hours. The administration of fentanyl was left to the discretion of the patient’s clinical team. While it is unlikely that the intraoperative administration of fentanyl impacted pain scores at 6 hours, dosing was not standardized and ISB subjects received higher total micrograms (ISB + Pecs II 43.2 ± 66.7 vs ISB 73.6 ± 67.2; P = .175). In addition, despite more patients in the ISB group receiving fentanyl and oxycodone in the PACU, this group still had significantly higher NRS pain scores at 6 hours.

While the patients were given preoperative benzodiazepines and a sham block was placed, we did not attempt to assess the blinding of our subjects during the phone interview at 24 hours. Also, to better quantify the analgesic efficacy of the Pecs II block for this surgery, we could have assessed NRS pain scores at more time points postoperatively using area under the curve methodology. Our postoperative nausea/vomiting rates were high and possibly related to withholding nonsteroidal anti-inflammatory drugs (NSAIDs) and intraoperative dexamethasone administrations. Regarding generalizability, if your orthopedic surgeon does not use an open subpectoral approach for bicep tenodesis, then these results have no applicability to your practice. These limitations may be incorporated when considering further investigation of this new analgesic peripheral nerve block.

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CONCLUSIONS

To the authors’ knowledge, this is the first study in which a Pecs II block was used in combination with an ISB for analgesia after an open subpectoral biceps tenodesis and a shoulder arthroscopy. This study demonstrates that the addition of a Pecs II block to an ISB significantly improves postoperative analgesia after an arthroscopic shoulder surgery with an open biceps tenodesis, as evidenced by a reduction in resting NRS pain scores and the presence of axillary pain at 6 hours, as well as the need for opioids in the PACU.

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DISCLOSURES

Name: J. Wells Reynolds, MD.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the paper.

Conflicts of Interest: None.

Name: Daryl S. Henshaw, MD.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: D. S. Henshaw declares that he is a member of the medical advisory board for Teleflex Medical (the maker of Arrow products).

Name: J. Douglas Jaffe, DO.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: None.

Name: Sean W. Dobson, MD, PhD.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: None.

Name: Christopher J. Edwards, MD.

Contribution: This author helped recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: None.

Name: James D. Turner, MD.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: None.

Name: Robert S. Weller, MD.

Contribution: This author helped design the study, recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: None.

Name: Benjamin R. Graves, MD.

Contribution: This author helped recruit the patient, collect and analyze the data, and write the manuscript.

Conflicts of Interest: B. R. Graves is a paid consultant for DePuy/Mitek and received fellowship and educational support from Smith and Nephew, Integra, and Arthrex.

Name: Michael T. Freehill, MD.

Contribution: This author helped design the study, recruit the patient, analyze the data, and write the manuscript.

Conflicts of Interest: M. T. Freehill is a consultant for and receives research support from Smith & Nephew. He is a consultant for Integra.

This manuscript was handled by: Richard Brull, MD, FRCPC.

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