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Transversus Abdominis Plane Block for Postoperative Analgesia in Patients Undergoing Total Laparoscopic Hysterectomy: A Randomized, Controlled, Observer-Blinded Trial

Ghisi, Daniela MD; Fanelli, Andrea MD; Vianello, Federico MD; Gardini, Marco MD; Mensi, Giulio MD; La Colla, Luca MD; Danelli, Giorgio MD

doi: 10.1213/ANE.0000000000001267
Regional Anesthesia and Acute Pain Medicine: Original Clinical Research Report

BACKGROUND: In this randomized, controlled, observer-blinded study, we evaluated analgesia provided by transversus abdominis plane (TAP) block after elective total laparoscopic hysterectomy in terms of reduced postoperative morphine consumption as the primary end point.

METHODS: Fifty-two patients were randomly divided into 2 groups: patients in group T (TAP, n = 26) received an ultrasound-guided bilateral TAP block with 40 mL of 0.375% levobupivacaine and morphine patient-controlled analgesia, whereas patients in group C (control, n = 26) received morphine patient-controlled analgesia. Secondary outcomes included pain measurements (Numeric Rating Scale from 0 to 10) during the first 24 hours postoperatively, times to postanesthesia care unit discharge, times to surgical ward discharge, incidence of postoperative nausea and vomiting, functional capacity measurements in terms of 2-minute walking test, and first oral solid intake.

RESULTS: Demographic and anthropometric variables were similar in the 2 groups. The total dose of morphine consumed by patients during postanesthesia care unit stay was 6 (0–8) mg in group T vs 8 (5.5–8.5) mg in group C (P = 0.154). Postoperative morphine consumption during the first 24 hours was 10.55 ± 10.24 mg in group C vs 10.73 ± 13.45 mg in group T (P = 0.950). The 95% confidence interval of the difference between means of 24-hour morphine consumption was −7.45 to +7.09. The 2 groups were comparable. There were no significant differences in secondary outcome variables between groups.

CONCLUSIONS: TAP block did not reduce morphine consumption during the first postoperative 24 hours after elective total laparoscopic hysterectomy.

Published ahead of print April 12, 2016

From the *Department of Anesthesia and Perioperative Medicine, Istituti Ospitalieri di Cremona, Cremona, Italy; Department of Gynaecology and Obstetrics, Istituti Ospitalieri di Cremona, Cremona, Italy; and Department of Anesthesia, Intensive Care and Pain Therapy, University Hospital Parma, Parma, Italy.

Published ahead of print April 12, 2016

Daniela Ghisi, MD, is currently affiliated with the Department of Anesthesia and Postoperative Intensive Care, Istituto Ortopedico Rizzoli, Bologna, Italy.

Andrea Fanelli, MD, is currently affiliated with the Department of Anesthesia and Intensive Care, Azienda Ospedaliero-Universitaria Sant’Orsola, Bologna, Italy.

Federico Vianello, MD, is currently affiliated with the Department of Gynecology and Obstetrics, Azienda Ospedaliera Carlo Poma di Mantova, Mantova, Italy.

Marco Gardini, MD, is currently affiliated with the Department of Anesthesia and Perioperative Medicine, Istituti Ospitalieri Cremona, Cremona, Italy.

Accepted for publication January 10, 2016.

Funding: Self-financed by the Department of Anaesthesia and Perioperative Medicine, Istituti Ospitalieri, Cremona, CR, Italy.

The authors declare no conflicts of interest.

This report was previously presented, in part, at the XIX European Society of Regional Anesthesia Italian Meeting.

Reprints will not be available from the authors.

Address correspondence to Daniela Ghisi, MD, Department of Anesthesia and Postoperative Intensive Care, Istituto Ortopedico Rizzoli via GC Pupilli, 1 40136 Bologna, BO, Italy. Address e-mail to ghisidan@hotmail.com.

Laparoscopic hysterectomy is associated with reduced postoperative pain and complications when compared with total hysterectomy.1 Nevertheless, many patients still experience significant postoperative pain even after laparoscopic procedures. Moreover, pain after laparoscopy is multifactorial, including somatic, visceral, and referred etiologies,2 and therefore, it often requires a multimodal therapeutic approach.3

The transversus abdominis plane (TAP) block is a regional technique that anesthetizes the nerves of the lower anterior abdominal wall, specifically from T10 to L1.4 Although some previous publications have demonstrated that TAP block results in significantly shorter length of stay and lower opioid use in women undergoing total laparoscopic hysterectomy,5 other studies have failed to show a significant improvement in quality of recovery, pain scores, and postoperative opioid request in similar clinical settings.1

We hypothesized that single-injection bilateral TAP block reduces morphine consumption in patients undergoing laparoscopic hysterectomy.

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METHODS

After obtaining approval from the Istituti Ospitalieri di Cremona ethics committee in February 2012, we evaluated 52 female patients between ages 18 and 70 years, with ASA physical status I to III, undergoing elective total laparoscopic hysterectomy in this observer-blinded, randomized, controlled trial. Patients were excluded in case of chronic opioid therapy in the 3 months before surgery, conversion to open surgical technique, body mass index >30 kg/m2 or <18 kg/m2, postoperative recovery in intensive care unit, chronic therapy with antidepressants, known diagnosis of epilepsy or therapy with antiepileptic drugs, bilirubin level >3.0 mg/dL, aspartate aminotransferase and/or alanine aminotransferase >250 IU, creatinine level >1.4 mg/dL, pregnancy or lactation, known allergy to any drug used in the study, local infection at the block site, and drug or alcohol addiction. The study was registered at ClinicalTrials.gov (NCT01552148).

At the time of arrival to the surgical ward and after obtaining the written informed consent, all patients performed a 2-minute walking test (2MWT) to establish a baseline value for functional capacity.6 Afterward, patients were randomized into 2 groups following a computer-generated sequence of numbers. For each randomized patient, the operating room (OR) anesthesiologist took the corresponding sealed envelope from a folder, indicating treatment assigned to the patient. In group T (TAP, n = 26), patients received an ultrasound (US)-guided bilateral TAP block with 40 mL of 0.375% levobupivacaine (20 mL for each side) and morphine patient-controlled analgesia (PCA) IV (bolus 2 mg, every 8 minutes, no hourly limit) for the first postoperative 24 hours. Patients in group C (control, n = 26) received the same morphine PCA. The anesthesiologist who performed the block was therefore unblinded to randomization. During anesthesia induction and block placement, an observer blinded to group allocation remained outside the OR and was called back to the OR at the beginning of surgery for data collection.

At the time of patients’ arrival to the OR, vital signs (noninvasive blood pressure with automated cuff, 3-lead electrocardiogram, and pulse oximetry) were registered. We assessed each patient’s risk for developing postoperative nausea and vomiting (PONV) with the Apfel score (Table 1).7 A crystalloid infusion was started and maintained at a rate of 5 mL/kg for the first 15 minutes and then reduced to 2 mL/kg/h during the surgical procedure.

Table 1

Table 1

Five minutes before induction of general anesthesia, a continuous infusion of remifentanil (0.2 μg/kg/min) was started and maintained, allowing rate adjustments (±0.05 μg/kg/min). General anesthesia was induced and maintained with target controlled infusion propofol infusion (initial target effect-site concentration 4 μg/mL) and titrated to keep bispectral index values between 40 and 60. Orotracheal intubation was facilitated with either cisatracurium (0.15–0.20 mg/kg) or suxamethonium (1 mg/kg) in cases of anticipated difficult intubation.

After induction of general anesthesia, patients in group T received a bilateral US-guided TAP block. After skin disinfection and preparation of sterile field, a linear array transducer (13–8 MHz) was applied between the costal margin and the iliac crest at the midaxillary line to visualize the 3 layers of the anterolateral abdominal wall. A 21-gauge, 110-mm, sonographic needle (SonoTAP Needle; Movi, Milan, Italy) was then inserted in plane and directed toward the fascia between the transversus abdominis and the internal oblique muscles; 20 mL of 0.375% levobupivacaine was injected at each side under direct US visualization. All surgical procedures were performed by the same surgeon using the same technique. The patient was placed in lithotomy position with 30 degrees of Trendelenburg. After direct placement of the 12-mm umbilical trocar, the carbon dioxide pneumoperitoneum was created at 14 mm Hg. Two suprapubic and lateral trocars (5-mm diameter) were inserted. The fourth trocar (12 mm) was inserted 4 to 5 cm above the umbilicus, slightly on the left, to obtain a wider visual angle. Procedures were performed using an advanced multifunctional bipolar forceps (Enseal-Ethicon Endosurgery; Johnson & Johnson, Rome, Italy).8,9 No peritonealization was performed and no drains were placed. Before the end of surgery, pneumoperitoneum was drained using trocar accesses.

Residual curarization was treated with neostigmine (0.02 mg/kg) and atropine (0.01 mg/kg). Total consumptions of propofol and remifentanil were recorded. The urinary catheter was removed at the end of the procedure (except in cases of a higher risk of bleeding as referred by the surgeon).

Vital signs (BP, HR, RR, and SpO2) were recorded every 15 minutes during surgery and after patients were extubated. After extubation, patients of both groups were transferred to the postanesthesia care unit (PACU) as soon as they were able to accomplish simple verbal orders and perform a 5-second head lift. Once in the PACU, vital signs, episodes of nausea/vomiting, and White score of each patient (Table 2) were recorded every 5 minutes for the first postoperative 30 minutes since extubation and then every 15 minutes until PACU discharge (White score of 12/14 without any item scoring 0). Pain severity was assessed using a Numeric Rating Scale (NRS) of 0 to 10. Once discharged to the surgical floor, the Post-Anesthesia Discharge Scoring System (Table 3) was administered to each patient every 30 minutes until a score of ≥9/10 was reached (allowing home discharge). Starting from 30 minutes after extubation and then every 30 minutes, patients were asked for spontaneous micturition. Time to first spontaneous voiding was recorded. Episodes of urinary retention were registered in both groups. Postoperative pain at rest and during movement was measured with NRS scale at 2, 4, 6, and 24 hours.

Table 2

Table 2

Table 3

Table 3

The PACU nurse administered a bolus dose of morphine (2 mg) every 10 minutes until NRS score at rest was <5/10. At the time of PACU discharge, patients were given a morphine PCA (bolus dose of 2 mg, 8 minutes of lockout, no 1-hour limit). Patients with a PONV score of >1 (ie, episodes of vomiting) were treated with metoclopramide 10 mg IV.

When a White score equal to 12/14 was reached, we requested the patient to stand up and walk for 2 minutes to test functional capacity (2MWT). The distance covered was measured in meters and compared with the baseline value of the preoperative 2MWT. In case of patients’ refusal, the 2MWT was proposed every 30 minutes until patients’ accomplishment. Times to first meal were registered. At 24 hours, the PCA pump was removed, and total morphine consumption was recorded.

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Statistical Analysis

The primary end point of the study was the difference in morphine consumptions in the first postoperative 24 hours between group T and group C. Secondary outcomes were pain measurements (NRS from 0 to 10) during the first 24 hours postoperatively, times to PACU discharge, times to surgical ward discharge, PONV incidence, functional capacity measurements in terms of 2MWT, and first oral solid intake.

Considering a mean morphine consumption/24 hours in laparoscopic hysterectomy of 22 ± 13.1 mg,10 an α error of 0.05, and a power (1 − β) of 0.08, 46 patients were required to highlight a difference of 50% in morphine consumption. We then added 6 patients to compensate for dropouts; therefore, 52 patients were enrolled.

To evaluate normality of the data, the Shapiro-Wilk test was applied. If normally distributed, data were expressed as mean ± SD and analyzed with parametric tests. If non-normally distributed, data were expressed as median (interquartile range) and analyzed with nonparametric tests. A repeated-measures analysis of variance was used to test the difference in continuous variables over time. Statistical analysis was performed with SPSS 21 (SPSS, Bologna, Italy).

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RESULTS

Fifty-two patients were enrolled in this randomized, controlled, observer-blinded study. Patients 16 and 17 withdrew their consent before randomization; patients 18, 38, and 46 received other analgesics or hypnotics that not accepted in the protocol; and patients 25, 33, and 50 had an conversion to open surgery or surgery required a more invasive approach than total hysterectomy and were, therefore, dropped out from the protocol. As shown in Figure 1, 44 patients completed the study: 22 in group T and 22 in group C.

Figure 1

Figure 1

The 2 groups were similar in terms of age, height, weight, ASA physical status distribution, and Apfel score (Table 4). Patients in group T walked 122 ± 38 m vs 129 ± 38 m in group C during the baseline 2MWT (P = 0.541).

Table 4

Table 4

Morphine consumption is reported in Table 5. The 95% confidence interval of the difference between means of 24-hour morphine consumption was −7.45 to +7.09. The 2 groups were comparable. There was no interaction between group and morphine consumption over time (P = 0.915), and morphine consumption was comparable between groups during PACU stay and during the first postoperative 24 hours (P = 0.154, P = 0.950).

Table 5

Table 5

Mean (SD) duration of anesthesia was 129 ± 38 minutes in group T vs 116 ± 34 minutes in group C (P = 0.260). At awakening, patients showed comparable time intervals to head lift (0 [0–2] minute in group T vs 0 [0–1] minute in group C; P = 0.657) and comparable time intervals to the execution of verbal orders (0 [0–1] minute in group T vs 0 [0–1] minute in group C; P = 0.900).

NRS scores for pain at awakening from total intravenous anesthesia were comparable between groups (P = 0.086). At the time of patients’ arrival in the PACU, 16 patients in group T (73%) and 20 patients in group C (91%) showed an NRS score for pain at rest of >5 (P = 0.240) and were therefore treated per protocol by the PACU nurse. In PACU, patients in group T took 30 (8–45) minutes vs 43 (25–46) minutes in group C to achieve an NRS score of <5 (P = 0.350). NRS scores for pain at rest and during movement were comparable between groups (Table 6).

Table 6

Table 6

Patients’ score for PONV in PACU did not differ between groups (P = 0.196).

One patient per each group (5%) reported 1 episode of hypotension in PACU (P = 1.000). There was no case of hypoxemia or bradycardia reported in any of the 2 groups during patients’ PACU stay.

Group T took a median of 5 (0–25) minutes, whereas group C took a median of 28 (13–45) minutes to reach a White score of >12 (P = 0.012).

Patients in group T took 62 ± 41 minutes vs 58 ± 21 minutes in group C to walk unassisted after a White score of >12 was reached (P = 0.726). The median distances covered during the 2MWT were also comparable between groups: 46 ± 23 m in group T vs 43 ± 24 m in group C (P = 0.697). Spontaneous voiding was achieved in 6 ± 6 hours in group T vs 5 ± 5 hours in group C (P = 0.472). Time to first meal was 8 (4–13) hours in group T vs 5 (4–11) hours in group C (P = 0.320). The distribution of Post-Anesthesia Discharge Scoring System >9 in the 2 groups was comparable (P = 0.143).

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DISCUSSION

This study demonstrated that bilateral US-guided TAP block did not reduce morphine consumption or pain scores at rest or movement during the first 24 hours after laparoscopic hysterectomy compared with control group. Neither the TAP block group nor the control group received multimodal analgesic therapy. A recent meta-analysis by De Oliveira et al11 on the analgesic effectiveness of TAP block for patients undergoing laparoscopic surgery demonstrated modest reduction in IV morphine equivalents of 5.74 mg over 24 hours and postoperative scores for pain at rest.

The study presents some limitations. First, previous studies12,13 have shown that laparoscopic hysterectomy can be performed as an outpatient procedure with multimodal oral analgesics, whereas our methodology includes hospital admission and IV PCA. Nevertheless, in our clinical research setting, the opioid PCA represented the easiest way to compare opioid consumption between groups, confirming very low requests by our patients. The second limitation is represented by the lack of double-blinding because the control group did not receive a sham block. The choice was guided by ethical considerations, whereas the blinding of the observer who collected the study data minimized biases. The third limitation is that the study may be not adequately powered because number of dropouts exceeded our expectations. Thus, we cannot exclude the possibility that a larger population could have shown some positive results in terms of pain and opioid request.

In conclusion, the results of this trial indicate that bilateral US-guided TAP blocks do not reduce 24-hour morphine requirements after laparoscopic hysterectomy.

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DISCLOSURES

Name: Daniela Ghisi, MD.

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

Name: Andrea Fanelli, MD.

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

Name: Federico Vianello, MD.

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

Name: Marco Gardini, MD.

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

Name: Giulio Mensi, MD.

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

Name: Luca La Colla, MD.

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

Name: Giorgio Danelli, MD.

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

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

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