Continuous Interscalene Block in Patients Having Outpatient Rotator Cuff Repair Surgery: A Prospective Randomized Trial : Anesthesia & Analgesia

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Pain Medicine: Research Report

Continuous Interscalene Block in Patients Having Outpatient Rotator Cuff Repair Surgery

A Prospective Randomized Trial

Salviz, Emine Aysu MD*; Xu, Daquan MD*; Frulla, Ashton*; Kwofie, Kwesi MD, FRCPC*; Shastri, Uma MD, FRCPC*; Chen, Junping MD*; Shariat, Ali Nima MD*; Littwin, Sanford MD*; Lin, Emily MD, PhD*; Choi, Jason MD*; Hobeika, Paul MD; Hadzic, Admir MD, PhD*

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Anesthesia & Analgesia 117(6):p 1485-1492, December 2013. | DOI: 10.1213/01.ane.0000436607.40643.0a
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Abstract

Arthroscopic shoulder surgery is a common outpatient orthopedic procedure. Postoperatively, many patients report pain severe enough to interfere with sleep1–4 and may require significant opioid treatment orally for several days. Heavy opioid treatment can, in turn, lead to somnolence, nausea, and/or vomiting.1,5–10

The advantages of the interscalene brachial plexus block (ISB) over general anesthesia (GA) and of continuous interscalene brachial plexus block (CISB) via interscalene catheters have been reported.7–9,11–13 However, previous studies used single injection ISB (SISB) or CISB as intraoperative adjuncts to GA1–7,10,13–19 or were focused only on the immediate recovery period (up to 48 hours).5–8,10,13,15–17 Few studies extended their observations of SISB4,9,14,18 or CISB1–3 beyond 48 hours. No study has compared the analgesia benefits conferred by SISB and CISB as sole anesthesia modalities with GA through the intermediate recovery period ending on postoperative day 7.

We examined the intermediate recovery profile of patients receiving CISB, SISB, or GA for arthroscopic rotator cuff repair surgery. Our primary hypothesis was that highest pain numeric rating scale (NRS) (worst pain score) at the end of the study week (postoperative day 7) would be lower for patients in the CISB group than for patients in the SISB and GA groups. We postulated that the early and prolonged use of local anesthetic (LA) infusion would lead to sustained pain relief. This was based on our surgeons’ anecdotal observation that patients who received continuous infusion of LA had significantly less pain at the end of the first week postoperatively.

We studied the effects of the 3 anesthetic techniques when used intraoperatively as a sole anesthesia modality on pain through the first postoperative week. We also studied time-to-first pain, analgesic consumption, fast-tracked postoperative anesthesia care unit (PACU) bypass rate, length of PACU stay, time-to-discharge home, total hours of sleep, and related adverse effects.

This prospective randomized clinical trial is registered on ClinicalTrials.gov (NCT01881776) and reported according to the Consolidated Standards of Reporting Trials (CONSORT) statement.20

METHODS

After IRB approval and written informed patient consent were obtained, 71 ASA physical status I to III patients, ≥18 years of age, body mass index (BMI) ≤35 kg/m2, and scheduled for elective arthroscopic supraspinatus rotator cuff repair and acromioplasty surgeries were enrolled in this prospective randomized clinical study in St Luke’s-Roosevelt Hospital Center, New York, NY, between August 2011 and June 2012. Patients were excluded if they had open shoulder procedures, difficulty understanding the instructions for using the anesthetic infusion pump and/or pain scales, contraindications to regional anesthesia (e.g., allergy to a LA, local infection, and coagulopathy), significant neurologic disorders of the upper extremity, psychiatric or cognitive disorders, history of substance abuse, or chronic opioid use. Patients were randomized using the sealed envelopes technique to CISB, SISB, or GA groups and were informed about the study before anesthesia and surgery started.

Before any anesthetic techniques were performed, all patients had peripheral IV lines placed, and oxygen was administered via a facemask. Standard American Society of Anesthesiologists monitors (electrocardiogram, arterial noninvasive blood pressure, and oxygen saturation) were applied. All patients were premedicated with IV 2 mg midazolam and 50 µg fentanyl. Attending anesthesiologists or regional anesthesia fellows under their supervision performed all blocks. Patients in all groups received 1000 mg acetaminophen IV intraoperatively.

SISB and CISB Groups

SISB was performed with ultrasound guidance and nerve stimulation.21 Patients were in supine position with the head turned to the contralateral side. The skin was disinfected with 10% povidone-iodine. A high-frequency linear transducer (BK Medical 400, equipped with a linear transducer (5–12 MHz), Herlev, Denmark) covered with a sterile plastic sleeve (Safersonic, Medizinprodukte Handlesg.m.b.H. Ybbs, Austria) was placed on the operative side of the neck to obtain the transverse view of the brachial plexus roots or trunks. The interscalene trunks/roots were identified between the anterior and middle scalene muscles. After skin anesthesia, a 5 cm 22-gauge insulated block needle (Stimuplex®A, B Braun Medical, Bethlehem, PA) was inserted in-plane laterally to medially to place the needletip between the upper and middle trunks of the brachial plexus (C5-C6). An electrical nerve stimulator (Stimuplex®Dig RC; B Braun Medical, Bethlehem, PA) was also used to confirm the location of the needletip by eliciting contraction of the deltoid or biceps muscles between 0.8 and 0.5 mA with a pulse width of 0.1 millisecond. After negative aspiration and in-line pressure monitoring to ensure an injection pressure of ≤15 psi (BSmart, Concert Medical, Norwell, MA), 20 mL 0.5% ropivacaine was injected. When an evoked motor response at ≤0.5 mA was present or injection could not commence with (opening) pressure ≤15 psi, the injection was aborted and the needle repositioned. Adequate spread of the LA constituted injection of LA between the middle and anterior scalene muscles. Additional needle adjustments and injections were made only when the spread of LA was not between the upper and middle trunks of the brachial plexus (C5-C6) and was therefore considered inadequate.

The same strict aseptic technique and positioning were followed for CISB. A 5 cm, 18-gauge insulated stimulating needle (Contiplex® Tuohy, B. Braun Medical, Bethlehem, PA) was inserted in-plane laterally to medially to place the needletip between the upper and middle trunks of the brachial plexus (C5-C6). After eliciting contraction of the deltoid or biceps muscles at 0.5 mA and/or adequate needletip placement, a nonstimulating catheter was inserted approximately 3 cm beyond the tip of the needle, and the needle was withdrawn over the catheter. After negative aspiration, the position of the catheter tip was verified between the upper and middle trunks of the brachial plexus (C5-C6) within interscalene sheet by injecting 1 mL 0.5% ropivacaine and then the rest of 20 mL 0.5% ropivacaine through the catheter. The catheter was secured with Grip-Lock® (Baxter Healthcare Corporation, Deerfield, IL) and covered with sterile tape instead of tunneling.

Block success for both CISB and SISB was defined as complete sensory loss to pinprick with a paper clip on the skin over the deltoid muscle at 30 minutes and ability to complete surgery with IV sedation using infusion of propofol while maintaining meaningful patient contact, spontaneous breathing with an oxygen mask, and without conversion to GA. Additional injections of LA through the interscalene catheter or into the shoulder joint by the surgeon were not allowed.

Anesthesia duration for SISB and CISB groups was defined as the time between the injection of LA through the needle or catheter and when the patient left the operating room after surgery was completed.

GA Group

GA was induced with propofol 2 to 3 mg/kg, fentanyl 2 µg/kg, and rocuronium 0.6 mg/kg. After insertion of an endotracheal tube, anesthesia was maintained with sevoflurane (1%–3%) in a mixture of nitrous oxide (50%) and oxygen (50%). Intraoperative boluses of fentanyl 25 µg were administered if heart rate or arterial blood pressure increased >20% above preinduction values. Sevoflurane was discontinued at the end of surgery. The lungs were then ventilated with 100% O2 at a fresh gas flow rate of 8 L/min. Any residual muscle relaxant was reversed with neostigmine. All patients also received IV ondansetron 4 mg. Anesthesia duration for the GA group was defined as the time between the induction of anesthetics and when the patient left the operating room after tracheal extubation.

All the arthroscopic rotator cuff surgeries were performed by the same surgeon, and the patients were followed by regional anesthesia fellows or attending anesthesiologists in the operating rooms. LA for the port insertions sites was injected by the surgeons using 1% of lidocaine with1:3,000,000 epinephrine. At the end of surgery, the duration of anesthesia and surgery were both recorded, and the patients were transported to the PACU. Patients with an interscalene catheter received a continuous infusion of ropivacaine 0.2% 5 mL/h with patient-controlled boluses of an additional 5 mL with a lockout time of 60 minutes by an infusion pump (INFUSOR® System, Baxter Healthcare Corporation, Deerfield, IL.) The interscalene catheters were removed 48 hours after surgery. Our routine clinical practice is that patients remove catheters at home themselves; however, for study purposes, patients were required to come to the ambulatory surgery unit for catheter removal, inspection of the catheter insertion site, completion of 48 hours data, and to collect any information on equipment-related (catheter, dressing, infusion pump) complaints or complications.

White’s Fast-Tracking Scoring System for PACU nurses was used to assess patient emetic symptoms, pain, heart rate, oxygen saturation, respiratory stability, hemodynamic stability, and physical activity. Patients were discharged at a minimum score of 12 (if no score was <1 in any category on White’s scale).22

All patients were prescribed acetaminophen (500 mg) with hydrocodone (7.5 mg) every 4 hours as needed to control postoperative pain before hospital discharge.

Our primary hypothesis was that highest NRS pain rating (worst pain score) at the end of the study week (postoperative day 7) would be lower for patients in the CISB group than for patients in the SISB and GA groups. Postoperative highest pain scores through the first postoperative week, time-to-first pain, analgesic consumption, fast-tracked PACU bypass rate, length of PACU stay, time-to-discharge home, total hours of sleep, and related adverse effects were recorded in the PACU and at home on postoperative days 1, 2, 3, and 7, respectively, as secondary end points.

The data were obtained by different clinical and research fellows blinded to group allocation at the hospital until discharge and over the phone after discharge through the entire postoperative week. After surgery, patients were adequately covered in the PACU. The following data were recorded until discharge: fast-tracked PACU bypass rate, length of stay in PACU, time-to-discharge home after surgery completed and if positive or adverse effect. Only the CISB group had their data recorded for the first 48 hours. All the rest of the group patient data on postoperative days 1, 2, 3, and 7 were obtained over the phone at home.

Statistical Analysis

Continuous variables are presented as mean ± standard deviation (SD), nominal and ordinal (categorical) variables as n (%). One-way analysis of variance was used to test mean differences in continuous variables among the 3 anesthesia groups (CISB, SISB, and GA). Its 2 group counterpart, the Student t test, was used to test mean differences in continuous variables when appropriate (for instance, difference in needle duration would apply to the CISB and SISB groups but not to the GA group). For the parametric tests, normality was checked by Kolmogorov-Smirnov, and the Kruskal-Wallis test was used if the distribution of any variable did not satisfy the assumption of normality. χ2 or the Fisher exact test, as appropriate, was used to test differences in proportions in categorical variables. All tests were adjusted for multiple comparisons. The 1-way analysis of variance is fairly robust to unequal variances; however, for tests of pairwise differences among means, the Tamhane T2 and Games-Howell were used when equal variances could not be assumed. For tests of differences among proportions, pairwise comparisons were tested against a P-value of 0.017 (0.05/3). The Statistical Package for the Social Sciences (SPSS for Windows, version 17, Chicago, IL, 2009) was used for all analyses.

Our end point for intermediate recovery, highest pain score at the end of the study week (postoperative day 7), was the primary outcome in our study; 95% confidence intervals (CIs) for the primary end point (differences in proportions with NRS <4 on postoperative day 7) were based on the Wilson score intervals for 2 proportions as described by Newcombe.23 A moderate difference in NRS (4 points) and SD for NRS (3 points) were used to estimate sample size. A sample size of 18 per group was initially estimated with α 0.01 and 1 − β 0.90 but was increased to 20 per group to accommodate any losses to follow-up and to enable testing of secondary end points that are included in the intermediate recovery profile.

RESULTS

Seventy-one patients scheduled for elective arthroscopic supraspinatus rotator cuff repair and acromioplasty surgery were eligible. One patient was excluded because of preference of SISB instead of GA, and 70 were randomized to one of the 3 groups between August 2011 and June 2012. Seven patients were subsequently excluded; 3 because surgery was changed from an arthroscopic to an open procedure, and 4 were lost to follow-up (in 1 CISB patient, the catheter was accidently removed; the patient was subsequently lost for follow-up) (Fig. 1). Among the 63 patients who completed the study (mean age 55 ± 11 years, mean BMI 0.30 ± 0.05 kg/m2), 20 patients had been assigned to CISB, 23 to SISB, and 20 to GA. Patients were predominantly ASA physical status II (67%). Overall, slightly more women than men patients were enrolled; however, randomization yielded groups that did not differ by gender, age, BMI, ASA physical status, or presence of co-occurring conditions (Table 1). No patient had overt complications of anesthetic intervention, and no patient had any specific CISB infusion-related complaints.

T1-30
Table 1:
Demographic Characteristics and Clinical Features of 63 Patients Randomly Assigned to One of the 3 Study Groups for Arthroscopic Shoulder Surgery
F1-30
Figure 1:
Consolidated Standards of Reporting Trials (CONSORT) diagram of SISB, CISB, and GA groups. SISB = single injection interscalene brachial plexus block; CISB = continuous interscalene brachial plexus block; GA = general anesthesia.

Primary End Point

By the end of the study week, as a result of our primary hypothesis, most patients in the CISB group (74%) reported NRS <4; in contrast to the proportions of patients in the SISB and GA groups who reported NRS ≥4 (83% and 58%, respectively, both P-values ≤0.05). Mean NRS was lower for patients in the CISB group than in the SISB and GA groups on postoperative days 1 and 2 and lower for patients in the CISB group than in the SISB group by the end of the study week. The difference between the proportions of CISB and SISB patients with NRS <4 on postoperative day 7 was 0.56 (95% CI, 0.33–0.80); between the proportions of CISB and GA patients with NRS <4 on postoperative day 7, it was 0.31 (95% CI, 0.06–0.57).

Secondary End Points

Time to accomplish the block was longer in the CISB group compared with the SISB group (11 ± 11 vs 6 ± 3 minutes, respectively, P = 0.03); mean difference 5 ± 2 minutes, 95% CI, 0.5–10 minutes. Overall duration of surgery and anesthesia care did not differ among the 3 groups (Table 1).

For the CISB group, length of stay in the PACU did not differ from the SISB group (P = 0.726) but was shorter than the GA group. The mean difference in length of stay in the PACU between the CISB and GA groups was 146 ± 27 minutes, P < 0.001; 95% CI, 75–216 minutes; mean difference between the SISB and GA groups was 135 ± 28 minutes, P < 0.001; 95% CI, 64–207 minutes. Time to first pain report in the CISB group was longer than the SISB and GA groups. The mean difference in time to first pain between the CISB and SISB groups was 15 ± 5 minutes, P = .037, 95% CI, 1–29 minutes; mean difference between the CISB and GA groups was 24 ± 5 minutes, P = 0.001, 95% CI, 10–37 minutes. While most patients in the CISB and SISB groups were fast-tracked to PACU discharge, no patient in the GA group was fast-tracked to PACU discharge (Χ2P = 0.003). No patient in the CISB group reported a NRS score ≥1 or required analgesics in the PACU. Time-to-discharge home did not differ between CISB and SISB groups (P = 0.84) but was significantly shorter when compared with the GA group. The mean difference in length of hospitalization between the CISB and GA groups was 208 ± 59 minutes, P = 0.006; 95% CI, 55–360 minutes; mean difference between the SISB and GA groups was 187 ± 62 minutes, P = 0.017; 95% CI, 29–346 minutes. Although the incidence of postoperative nausea and vomiting (PONV) in the PACU was infrequent and did not differ among groups (Pearson Χ2P = 0.12), no patient who received CISB experienced PONV while in the PACU (Table 2).

T2-30
Table 2:
PACU Bypass, Length of Stay, Analgesia, and Incidence of PONV

On postoperative days 1 and 2, use of narcotics (doses ≥1) was lower among patients who received CISB than among patients who received SISB or GA but did not differ among the groups by postoperative day 3. The incidence of postoperative dizziness and PONV did not differ among groups, though no patient in the CISB group reported PONV by the end of the study week. Total hours of sleep were longer for the CISB group compared with the SISB and GA groups on postoperative day 1 and longer than the SISB group by postoperative day 2 (Table 3). Total hours of sleep were approximately 6 ± 2 hours over all groups by the end of the study week.

T3-30
Table 3:
Postoperative Experience on Postoperative Days 1, 2, 3, and 7 of 63 Patients Given in 3 Study Groups

No lasting complications occurred in any of the groups during the study. One patient in the CISB group had transient difficulty breathing on arrival to the PACU. His breathing difficulty resolved within 2 hours of PACU admission, and his recovery at home was uneventful. There were no complications or complaints related to the equipment; most infusion pumps had 20 to 60 mL residual LA at the time of discontinuation. Finally, on postoperative day 10, none of our patients had hematoma during the postoperative visit.

DISCUSSION

The use of ISB either as a single injection or as a continuous infusion with patient-controlled catheter analgesia resulted in significantly faster discharge home and superior postoperative analgesia compared with GA during the intermediate recovery period. Nearly all ISB patients bypassed the PACU, and time-to-discharge home was approximately 3-fold shorter with ISB than with GA. Moreover, only a single patient required opioid analgesic intervention during the PACU stay compared with the most patients (89%) who received GA.

It is interesting to note that patients who received SISB slept fewer hours than patients who received GA. This may be because patients who receive SISB experience more pain as their blocks wear off.14,19 That is, patients who receive GA may have already established an effective analgesic regimen through oral opioids immediately after surgery, whereas patients who receive SISB have no established oral analgesic regimen on-board when the block wears off at home. Indeed, in our previous study comparing SISB as a single anesthetic modality versus GA alone, analgesic and recovery benefits appeared to be limited to the duration of the blockade.9

Several investigators have reported substantial patient benefits from CISB or SISB compared with GA.7–9,11,12 Borgeat et al.24 reported that the use of ropivacaine 0.3% through an interscalene catheter for the first 48 hours after open rotator cuff repair provided a significant reduction of morphine consumption and better sleep quality for the first postoperative night without increasing the intensity of motor block or side effects compared with the ropivacaine 0.2% group. In a study by Ilfeld et al.,1 patients who had CISB for moderately painful arthroscopic surgery had less pain, postoperative opioid use, nausea, and sleep disturbances through postoperative day 2 than patients who had SISB. However, their SISB patients received a short-acting LA (mepivacaine). In our study, CISB conferred substantially longer analgesia and sleep benefit over SISB, even when long-acting LA (ropivacaine) 0.2% was used for SISB. In this regard, our findings are similar to that of Mariano et al.3 who used long-acting LA (ropivacaine) for outpatient shoulder surgery and reported that CISB resulted in additional analgesic benefit, less opioid use (67% of patients did not use supplemental opioids through postoperative day 2), fewer sleep disturbances, increased patient satisfaction, and longer time-to-first oral analgesic than SISB. However, in contrast to our study, all patients in that study received GA as their primary anesthetic and were not able to bypass the PACU despite the fact that they also received ISB.

In a study of postoperative pain in patients having minor shoulder surgery, Fredrickson et al.12 found that CISB decreased postoperative pain compared with SISB, but only through the first 24 hours after surgery, although the consumption of tramadol continued to be lower in patients with CISB through 48 hours postoperatively. The benefits of CISB in our study are most likely related to the fact that our patients had significantly more extensive surgery than patients in the study by Fredrickson et al.12 Moreover, we found that the analgesic benefits of CISB persisted through the end of the study week.

Our study has several shortcomings. Blinding was not optimal as patients who received SISB and GA only did not receive sham catheters. To avoid data collection bias, patients were adequately covered until their discharge home. In addition, study data were obtained in person by different clinical and research fellows before discharge from the hospital and after discharge at home by phone through the rest of the data collection period. Likewise, active mobilization was not compared between the groups on day 7.

In conclusion, CISB confers important recovery and analgesic benefits in outpatients having arthroscopic rotator cuff surgery. While both CISB and SISB conferred better analgesia, faster recovery, and discharge home than GA only, these benefits were sustained through the first postoperative week only in patients who received CISB. Our findings also emphasize the need for routine structured oral analgesic protocols in patients receiving SISB to decrease the risk for and intensity of rebound pain and sleep disturbances that may occur as the block wears off.

DISCLOSURES

Name: Emine Aysu Salviz, MD.

Contribution: This author helped conduct the study, analyze the data, and write the manuscript.

Attestation: Emine Aysu Salviz has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Daquan Xu, MD.

Contribution: This author helped design and conduct the study and analyze the data.

Attestation: Daquan Xu has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: Dr Xu was hired to perform this study (Baxter).

Name: Ashton Frulla.

Contribution: This author helped design and conduct the study.

Attestation: Ashton Frulla has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Kwesi Kwofie, MD, FRCPC.

Contribution: This author helped conduct the study and write the manuscript.

Attestation: Kwesi Kwofie has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Uma Shastri, MD, FRCPC.

Contribution: This author helped conduct the study and write the manuscript.

Attestation: Uma Shastri has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Junping Chen, MD.

Contribution: This author helped conduct the study and write the manuscript.

Attestation: Junping Chen has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Ali Nima Shariat, MD.

Contribution: This author helped conduct the study and write the manuscript.

Attestation: Ali Nima Shariat has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Sanford Littwin, MD.

Contribution: This author helped write the manuscript.

Attestation: Sanford Littwin has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Emily Lin, MD, PhD.

Contribution: This author helped write the manuscript.

Attestation: Emily Lin has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Jason Choi, MD.

Contribution: This author helped write the manuscript.

Attestation: Jason Choi has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Paul Hobeika, MD.

Contribution: This author helped conduct the study.

Attestation: Paul Hobeika has seen the original study data, reviewed the analysis of the data, and approved the final manuscript.

Conflicts of Interest: The author has no conflicts of interest to declare.

Name: Admir Hadzic, MD, PhD.

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

Attestation: Admir Hadzic has seen the original study data, reviewed the analysis of the data, approved the final manuscript, and is the author responsible for archiving the study files.

Conflicts of Interest: Dr. Admir Hadzic has consulted and advised for Skypharma, GE, Sonosite, Codman & Shrutleff, Inc (Johnson and Johnson), Cadence, Pacira, Baxter and BBraun Medical. His recent industry-sponsored research includes Glaxo Smith-Kline Industries, Pacira, Baxter. Dr. Hadzic is an equity holder at Macosta Medical USA, a USA-based intellectual property firm.

This manuscript was handled by: Spencer S. Liu, MD.

ACKNOWLEDGMENTS

The authors wish to thank Jeff Gadsden, MD, FRCPC, FANZCA, for his help with the patient enrollment.

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