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Anesthesia & Analgesia:
doi: 10.1213/ANE.0b013e318297fcee
Regional Anesthesia: Research Report

The Analgesic Efficacy of Subcostal Transversus Abdominis Plane Block Compared with Thoracic Epidural Analgesia and Intravenous Opioid Analgesia After Radical Gastrectomy

Wu, Yiquan MD*; Liu, Fuli MD*; Tang, Hongli MD*; Wang, Quanguang MD*; Chen, Limei MD*; Wu, Hui MD*; Zhang, Xuezheng MD*; Miao, Jianxia MD*; Zhu, Meizhen MD*; Hu, Chenggang MD, PhD; Goldsworthy, Mark MD; You, Jing MS§; Xu, Xuzhong MD*

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From the *Department of Anesthesiology, First Affiliated Hospital, Wenzhou Medical College, Zhejiang, China; Department of Anesthesiology, Pomerado Hospital, Poway, California; Department of Anesthesiology, Palomar Medical Center, Escondido, California; and §Departments of Quantitative Health Sciences and Outcomes Research, Cleveland Clinic, Cleveland, Ohio.

Accepted for publication April 5, 2013.

Published ahead of print June 6, 2013.

Funding: This study was supported by an international cooperation item from Department of Science and Technology of Wenzhou (No H20090013).

The authors declare no conflict of interest.

Reprints will not be available from the authors.

Address correspondence to Xuzhong Xu, MD, Department of Anesthesiology, the First Affiliated Hospital, Wenzhou Medical College, 2 Fuxue Rd., Wenzhou City, Zhejiang Province, China 325000. Address e-mail to xuzhong@263.net.

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Abstract

BACKGROUND: The transversus abdominis plane (TAP) block has been shown to provide effective postoperative analgesia in lower abdominal surgery. Subcostal TAP block has also been proposed as a new technique to provide analgesia for the supraumbilical abdomen. We compared the analgesic and opioid-sparing effects of a single-injection subcostal TAP block with continuous thoracic epidural analgesia and IV opioid analgesia.

METHODS: Ninety patients undergoing elective radical gastrectomy were randomized to receive either combined general–subcostal TAP anesthesia (group TAP), combined general–epidural anesthesia (group EA), or general anesthesia (group GA), and were analyzed on an intention-to-treat basis. In group TAP, a bilateral subcostal TAP block was performed after induction of general anesthesia using 20 mL of 0.375% ropivacaine. In group EA, a thoracic epidural was placed between T8 and T9 and bolused with 8 mL of 0.25% ropivacaine before induction of general anesthesia. The epidural was maintained with 5 mL/h of 0.25% ropivacaine during the surgery. Group GA received standard general anesthesia. In the postanesthesia care unit (PACU), all groups received IV morphine titration for visual analog scale (VAS) pain scores >3. All patients were started on IV patient-controlled analgesia with morphine after morphine titration in the PACU, while group EA also had their epidural maintained with 5 mL/h of 0.125% bupivacaine with 8 μg/mL morphine. Patients were assessed in the PACU and at 1, 3, 6, 24, 48, and 72 hours postoperatively. Primary outcomes measured were morphine consumption at 24 hours and all VAS pain scores.

RESULTS: Data from 82 of 90 (91.1%) patients were included in the study. Group TAP demonstrated decreased cumulative morphine consumption at 24 hours (98.75% confidence intervals, −29 to −9 mg) and noninferiority on VAS pain scores at all measurement times, as compared with group GA with standard opioid analgesia. However, group EA was superior to group TAP regarding cumulative morphine consumption at 24 hours (98.75% confidence intervals, −23 to −4 mg) and noninferior to group TAP on VAS pain scores at all comparison points. Group TAP had reduced morphine consumption from PACU admission to 6 hours as compared with group GA, but increased morphine consumption for 6 to 24 hours as compared with group EA.

CONCLUSION: Single-injection subcostal TAP block was more effective than IV opioid analgesia, while continuous thoracic epidural analgesia was more effective than the single-injection subcostal TAP block.

Radical gastrectomy is a major upper abdominal surgical procedure which can result in substantial postoperative pain. Traditionally, pain relief for these patients is provided by thoracic epidural analgesia or IV opioid analgesia. Although epidural analgesia is currently the “gold standard” for postoperative pain treatment, associated complications and contraindications may limit its use. IV opioid analgesia may cause opioid-related side effects and be associated with inadequate analgesia. Alternative approaches to traditional anesthetic techniques should be investigated.

The transversus abdominis plane (TAP) block has been increasingly used in clinical practice as a new analgesic technique for both upper and lower abdominal incisions. Previous reports1–5 have demonstrated the pain relief and the opioid-sparing effects of the TAP block in lower abdominal surgery during the first 24 postoperative hours, with occasional effectiveness up to 48 hours. The “subcostal” approach of the TAP block,6–8 described by Hebbard et al.,7 has been reported to provide analgesia to the supraumbilical abdomen. Lee et al.9 observed the subcostal approach in a clinical study and found that it blocked a median of 4 segments (interquartile range, 3–5), the most cephalad being T8 (interquartile range, T7–T9). Milan et al.10 reported that the subcostal TAP block decreased morphine consumption over 24 hours after orthotopic liver transplant surgery. However, more studies are warranted to establish general recommendations for the use of the TAP block.11,12 Although seemingly effective in lower abdominal surgeries, the effectiveness of the subcostal TAP block has yet to be compared with classic epidural analgesia and IV opioids in upper abdominal surgery.

We hypothesized that a single-injection subcostal TAP block would improve analgesia compared with IV opioid analgesia, but would be less effective than continuous thoracic epidural analgesia. Our primary outcomes were morphine consumption at 24 hours and all visual analog scale (VAS) scores. The secondary outcomes we assessed included intraoperative ephedrine consumption, morphine-related side effects, postoperative adverse events, and time to first flatus.

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METHODS

After obtaining approval by the Ethics Committee at the First Affiliated Hospital of Wenzhou Medical College and written informed patient consent, 90 patients scheduled for elective open radical gastrectomy for gastric cancer were enrolled in the study on an intention-to-treat basis. According to the allocation sequences generated by a random number table and the use of a sealed envelopes technique, patients were randomly assigned to 1 of 3 groups: combined general–subcostal TAP anesthesia (group TAP), combined general–epidural anesthesia (group EA), or standard general anesthesia (group GA). Exclusion criteria were as follows: ASA physical status ≥III; body mass index (BMI) ≥30 kg/m2 or ≤15 kg/m2; a history of relevant drug allergy; a history of alcohol or analgesics dependence; coagulopathy; peripheral neuropathy; and difficulty with communication.

Patients were informed about the analgesia decision tree on the day before surgery and were instructed on how to express pain intensity with use of the VAS13 (0 = no pain, 10 = the worst imaginable pain). No preoperative medications were administered. After arrival in the operating room, peripheral IV access was obtained and standard ASA monitors were applied. Additionally, each patient had a radial artery catheter inserted for frequent and accurate comparative analysis of arterial blood pressure monitoring.

General anesthesia was induced by IV propofol 1.5 to 2.0 mg/kg and sufentanil 0.3 µg/kg. Endotracheal intubation was facilitated by administration of IV rocuronium 0.9 mg/kg. After endotracheal intubation, intermittent positive pressure ventilation of both lungs was applied. Anesthesia was maintained with combined IV–inhaled anesthesia (propofol, remifentanil, and sevoflurane in oxygen). An infusion of remifentanil was started at 8 μg/kg/h and titrated upward to 12 μg/kg/h for control of hemodynamic responses to pain during surgery. In group TAP and group GA, 0.1 μg/kg sufentanil was given every 1.5 hours during surgery. In group TAP, a bilateral ultrasound-guided subcostal TAP block was performed as previously described7 after induction of general anesthesia, with 0.375% ropivacaine 20 mL on each side. In group EA, before induction of general anesthesia, a thoracic epidural catheter between T8 and T9 was placed, with 1.5% lidocaine 4 mL as a test dose. An initial loading dose of 8 mL 0.25% ropivacaine was administered before induction of anesthesia, and 5 mL was infused every hour during surgery. Group GA received standard general anesthesia. Ephedrine 5 mg IV was administered for systolic blood pressure (SBP) ≤80 mm Hg, or a 30% reduction during surgery, administration of an additional dose of ephedrine was permitted after 2 minutes. Suspension of the epidural infusion was allowed in the case of hypotension until hemodynamic stability was reestablished.

Group EA patients with pain on emergence from anesthesia were administered an epidural bolus of 5 mL of 0.375% ropivacaine. If there was no pain relief after the bolus, their sensory block level was established by using a pinprick technique. If no sensory block was noted, the epidural catheter would be resited; if the block level was adequate, the epidural catheter without an epidural infusion pump was concealed on the patient’s dorsum to ensure that the investigator in the postanesthesia care unit (PACU) was blinded as much as possible to the use of epidural analgesia.

In the PACU, all 3 groups received pain assessment and IV morphine titration14 which were performed by an attending anesthesiologist blinded to group allocation. When the VAS score was >3, morphine titration was started until pain relief was obtained, defined as VAS ≤3.14 The SBP, heart rate, peripheral pulse oximetry (SpO2), and respiratory rate were monitored. Sedation was evaluated using the Ramsay score15 (2–4: satisfactory sedation, >4: excessive sedation). Morphine titration was stopped if the patient appeared excessively sedated, and/or the presence of severe morphine-related side effects, including respiratory depression14 (SpO2 <95% and/or respiratory rate <12 breaths/min under 3 L/min oxygen flow), allergy reaction/cutaneous rash, hypotension, vomiting, or severe pruritus. After morphine titration, all 3 groups received IV patient-controlled analgesia (PCA) with morphine (1-mg bolus dose with a 5-minute lockout time and no maximum dose). Group EA also received continuous epidural analgesia maintained by epidural infusion pumps, with 5 mL/h background infusion of bupivacaine 0.125% with morphine 8 μg/mL. IV and epidural analgesia were both maintained through the first 72 postoperative hours. Patients on wards were observed by an alternate anesthesiologist who was not blinded to the group allocations due to the obvious epidural infusion pumps in the epidural group.

Demographic and intraoperative characteristics were recorded, including sex, age, height, weight, BMI, surgical duration, and intraoperative ephedrine consumption. After surgery, patients were assessed in the PACU and at 1, 3, 6, 24, 48, and 72 hours postoperatively. The recorded observations were as follows: morphine titration consumption in PACU, interval morphine PCA requirements after morphine titration, and cumulative morphine consumption including both morphine titration consumption and PCA requirements; pain sores including VAS scores at rest and on movement (cough or turn around the body); morphine-related side effects, such as sedation, dizziness, nausea, vomiting, pruritus, and respiratory depression; and postoperative adverse events, such as hypotension or hypertension (SBP <80 or >180 mm Hg, or fluctuations >30% of the baseline, duration >10 minutes), bradycardia or tachycardia (heart rate <50 or >120 beats/min, duration >10 minutes), adverse respiratory events and central nervous systemic complications, and time to first flatus.

Based on a pilot study, we estimated that the minimum detectable difference of cumulative morphine consumption at 24 hours was 18 mg, with a standard deviation of 12 mg. A sample size of 24 per group was obtained by PASS 11.0 (NCSS Statistical Software, Kaysville, UT), with α = 0.05 and β = 0.2. We planned to recruit 30 patients per group to minimize any effect of data loss.

SAS software version 9.3 (SAS Institute, Cary, NC) was used for statistical analysis. Balance on baseline characteristics among the randomized groups was assessed separately for each intervention, using the standardized difference. Any variable with an absolute standardized difference >0.52 (i.e.,

Equation (Uncited)
Equation (Uncited)
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) for either intervention would be adjusted for in the analyses.16,17

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Primary Analysis

For each comparison, i.e., continuous general–epidural anesthesia (CGEA) versus continuous general–TAP anesthesia (CGTA) and CGTA versus general anesthesia (GA), both outcomes (cumulative morphine consumption at 24 hours and all VAS pain scores) were analyzed together in a “joint hypothesis testing” framework as described in Mascha and Turan.18 In this framework, one intervention group was deemed more effective than another only if found noninferior on both VAS scores and morphine consumption and superior on at least 1 of the 2. For each comparison, the overall significance level of the joint hypothesis testing was 0.025 (0.05/2, Bonferroni correction for 2 comparisons). For each comparison, we tested in both directions, e.g., whether CGTA is better than CGEA, and whether CGEA is better than CGTA. Therefore, for a particular direction, noninferiority and superiority testing were conducted at 0.0125 (0.025/2), as described below.

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Noninferiority

Noninferiority, i.e., “as good as or better than,” of the specific comparison (CGEA versus CGTA and CGTA versus GA) on each outcome was evaluated in separate models (1 for each outcome) at the 0.0125 significance level. Since noninferiority was required for both outcomes, no adjustment for testing 2 primary outcomes was needed.

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Superiority

If noninferiority was concluded for both primary outcomes in a particular direction (and not both directions, which would imply equivalence), then the superiority of the corresponding comparison was evaluated for each outcome using overall α of 0.0125 with Holm-Bonferroni correction for testing 2 outcomes, i.e., criterion of P < 0.00625 for most significant outcome and P < 0.0125 for the other. If and only if superiority was detected on at least either pain or morphine consumption, the group was concluded to be better than its comparator.

We observed that the treatment effects on VAS pain score depended on both measurement time and condition (at rest and with movement) (treatment-by-time-by-condition interaction P = 0.002), using a linear mixed effects model with repeated measures. Thus, we estimated the difference in median of VAS score at each measurement time for both at rest and with movement, since VAS score was not normally distributed.

We used the confidence interval (CI) method for noninferiority and superiority testing. For each noninferiority comparison, noninferiority was claimed if the upper limit of the 97.5% 2-sided (corresponding to α of 0.0125 on upper tail) CIs for difference in means of cumulative morphine consumption at 24 hours was less than the noninferiority Δ of 10 mg, and if the difference in medians of VAS score was less than the noninferiority Δ of 1 (on the 10-point scale) at all measurement times for both at rest and on movement. Superiority was claimed if the upper limit of the 98.75% (for the most significant outcome) and 97.5% (for the least significant outcome) CIs (Holm-Bonferroni correction for multiple testing) was <0 for either morphine consumption or VAS pain score.

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Secondary Analysis

We compared all pairs of the randomized groups on intraoperative ephedrine consumption and time to first flatus, each by Wilcoxon test. All binary outcomes including morphine-related side effects and postoperative adverse events were compared by χ2 test or Fisher exact test, as appropriate. The significance criterion for each pairwise comparison on each secondary outcome was P < 0.0014, i.e., 0.05/36, Bonferroni correction.

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RESULTS

Ninety patients were enrolled in the study. Data from 82 patients, 27 from group TAP, 29 from group EA, and 26 from group GA were included in the final analysis. Seven patients, 1 from group EA, 3 from group TAP, and 3 from group GA, who had consented to our protocol the day before surgery, refused to participate in our study on the day of surgery, and 1 patient from group GA was transferred to the intensive care unit for postoperative respiratory failure. No data were collected from these 8 patients.

Additionally, 6 patients, 2 from each group, did not receive radical gastrectomy due to distant cancer metastases found at the time of surgery; and 3 patients from group EA had complications, 1 had a massive hemorrhage during surgery so epidural analgesia was discontinued, and 2 were changed to receive standard general anesthesia because of epidural puncture failure. However, these patients were included in the final analysis on an intention-to-treat basis.

The 3 groups were comparable in terms of sex, age, height, weight, BMI, and surgery duration (absolute standardized difference <0.50, Table 1). Therefore, no covariable was adjusted for in the analyses.

Table 1
Table 1
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TAP was found more effective than GA. Group TAP was noninferior to group GA on cumulative morphine consumption at 24 hours (97.5% CIs of the difference in means, −28 to −10 mg, Table 2) and pain score at all measurement times both at rest and on movement (Table 3). Furthermore, superiority was found on cumulative morphine consumption at 24 hours (98.75% CIs, −29 to −9 mg), but not on pain scores since only the estimated upper limits of the differences in pain scores at PACU at rest, and at PACU, 1, 3, and 6 hours on movement were below the superiority criteria of 0.

Table 2
Table 2
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Table 3
Table 3
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Group EA was found noninferior to group TAP on both cumulative morphine consumption at 24 hours (Table 2) and pain score at all measurement times for both at rest and with movement (Table 3), since the estimated upper limits of the 97.5% CIs for the difference in means of cumulative morphine consumption (−22 to −5 mg) and all the differences in medians of pain score were below the noninferiority criteria of 10 and 1 mg, respectively. Furthermore, group EA was found superior to group TAP on cumulative morphine consumption at 24 hours, since the estimated upper limits of the corresponding 98.75% CIs (−23 to −4 mg) was below the superiority criteria of 0. However, superiority cannot be claimed on pain score since only the estimated upper limits of the differences in pain scores at PACU admission and 24 hours at rest, and at PACU admission, 24, 48, and 72 hours on movement were below the superiority criteria of 0. Therefore, based on our joint hypothesis test we conclude that general–epidural anesthesia was more effective than general–TAP anesthesia for pain management.

In addition, group EA was found noninferior to group TAP on morphine consumption at each time interval; however, it was only superior to group TAP for 6 to 24 hours (Table 2). We also found that group TAP was noninferior to group GA on morphine consumption at each time interval; however, it was superior to group GA during morphine titration in the PACU and titration-6 hours (Table 2). Furthermore, group EA was superior to group TAP on cumulative morphine consumption at 24, 48, and 72 hours, while group TAP was superior to group GA on cumulative morphine consumption at 6, 24, 48, and 72 hours (Table 2).

Otherwise, intraoperative ephedrine consumption was significantly higher in group EA than in group TAP. There was no significant difference between any 2 groups in time to first flatus, morphine-related side effects, or other postoperative adverse events (Table 4).

Table 4
Table 4
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DISCUSSION

Our study demonstrated that single-injection subcostal TAP block was more effective than IV opioid analgesia, while continuous thoracic epidural analgesia was more effective than the single-injection subcostal TAP block. The joint hypothesis testing on both morphine consumption and pain scores indicated that the superiority of the 2 analgesic techniques was attributed to their opioid-sparing effect. The analgesic efficacy of single-injection subcostal TAP block was mainly present during the first 6 hours after radical gastrectomy.

Compared with IV opioid analgesia, single-injection subcostal TAP block reduced morphine consumption and pain scores in the early postoperative period from PACU admission to 6 hours, which is consistent with pain relief for 4 to 8 hours after single local injection of ropivacaine.19 Although there were no differences between the 2 groups in the PCA interval requirements for 6 to 24, 24 to 48, and 48 to 72 hours postoperatively, single-injection subcostal TAP block still reduced cumulative morphine consumption at 24, 48, and 72 hours postoperatively. This may have occurred because the cumulative need for morphine in the first 6 hours postoperatively may have been mitigated by the TAP block. In view of the previous studies, single-injection TAP block may confer special advantages in procedures with small to moderate surgical trauma and pain,11,12 e.g., cesarean delivery, open appendectomy, laparoscopic cholecystectomy, large bowel resection, and total abdominal hysterectomy. In our study, although single-injection subcostal TAP block improved analgesia after radical gastrectomy, its analgesic efficacy was mainly during the first 6 hours. Therefore, a study using a continuous infusion TAP catheter technique would be of interest. Recently, Niraj et al.20 performed subcostal TAP catheter boluses after major hepatobiliary or renal surgery and found no significant advantage of epidural analgesia over subcostal TAP catheter bolus analgesia.

Compared with the continuous thoracic epidural analgesia group, the single-injection subcostal TAP block group had increased morphine consumption for 6 to 24 hours and pain scores in the PACU and beyond 6 hours postoperatively. Several reasons may account for these findings: (1) TAP block only provides somatic pain relief as opposed to epidural anesthesia which provides both somatic and visceral analgesia; (2) the efficacy of single-injection subcostal TAP block will wane over time, while that of thoracic epidural catheters can be sustained; (3) epidural analgesia can reduce the intraoperative consumption of remifentanil and sufentanil, which may reduce the occurrence of hyperalgesia and acute opioid tolerance21,22 after surgery; and (4) the administration of opioids in epidural analgesia may decrease the need for IV opioids.

Our study has several limitations. First, because we evaluated only a single-injection subcostal TAP block, a continuous infusion catheter TAP block technique was not studied even though a continuous epidural approach was used for comparison. Second, the patients in the epidural group were permitted to receive an additional local anesthetic bolus after surgery in the event of inadequate pain relief, while the patients in the subcostal TAP group only received a single injection before surgery, which may have favored a bias toward the epidural group. Third, we used single blinding in the PACU for IV morphine titration, but not at other times. This was because the patients in the epidural group received an obvious epidural infusion pump after titration. Fourth, despite the use of real-time ultrasound for the performance of the subcostal TAP block, we did not test the sensory block plane in these patients. Finally, we excluded the patients with ASA physical status ≥III and BMI ≥30 kg/m2 or ≤15 kg/m2, which limits the external generalizability of the results in this study.

We have demonstrated that the ability to provide an intermediate option between general anesthesia with IV opioids and general anesthesia with an epidural infusion could be an effective modality under certain circumstances. While continuous thoracic epidural analgesia provides excellent sustained pain relief, single-injection subcostal TAP block improved early analgesia compared with IV opioid analgesia after radical gastrectomy. Future studies should focus on the use of continuous infusion catheter TAP blocks for extended analgesia in major abdominal surgeries.

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DISCLOSURES

Name: Yiquan Wu, MD.

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

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

Name: Fuli Liu, MD.

Contribution: This author helped conduct the study and study data collection.

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

Name: Hongli Tang, MD.

Contribution: This author helped conduct the study and study data collection.

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

Name: Quanguang Wang, MD.

Contribution: This author helped conduct the study and study data collection.

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

Name: Limei Chen, MD.

Contribution: This author helped design the study.

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

Name: Hui Wu, MD.

Contribution: This author helped conduct the study.

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

Name: Xuezheng Zhang, MD.

Contribution: This author helped conduct the study.

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

Name: Jianxia Miao, MD.

Contribution: This author helped conduct the study.

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

Name: Meizhen Zhu, MD.

Contribution: This author helped conduct the study.

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

Name: Chenggang Hu, MD, PhD.

Contribution: This author helped prepare the manuscript.

Attestation: Chenggang Hu has approved the final manuscript.

Name: Mark Goldsworthy, MD.

Contribution: This author helped revise the manuscript.

Attestation: Mark Goldsworthy has approved the final manuscript.

Name: Jing You, MS.

Contribution: This author helped analyze the data and revise the manuscript.

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

Name: Xuzhong Xu, MD.

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

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

This manuscript was handled by: Terese T. Horlocker, MD.

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ACKNOWLEDGMENTS

We would like to thank Prof. Thomas J. Papadimos, Department of Anesthesiology, the Ohio State University Medical Center, Columbus, Ohio, for his help in editing this manuscript. We also thank Dr. Edward J. Mascha, Departments of Quantitative Health Sciences and Outcomes Research, Cleveland Clinic, Cleveland, Ohio, for his help in our statistical work.

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