UNCORRECTED PROOF AUTHOR'S PROOF. 7 Gianpiero Gravante & Francesca Castrì & 8 Francesco Araco & Antonino Araco

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1 DOI /s SHORT COMMUNICATION 2 4 A Comparative Study of the Transversus Abdominis Plane 5 (TAP) Block Efficacy on Post-bariatric vs Aesthetic 6 Abdominoplasty with Flank Liposuction Q2 7 Gianpiero Gravante & Francesca Castrì & 8 Francesco Araco & Antonino Araco 9 10 # Springer Science+Business Media, LLC Abstract The transversus abdominis plane (TAP) block 13 acts on the nerves localised in the anterior abdominal wall 14 muscles. We evaluated the efficacy on post-bariatric (PB) 15 patients undergoing body-contouring abdominoplasty. We 16 retrospectively evaluated PB patients undergoing abdomi- 17 noplasty with flank liposuction and compared results to a 18 matched group of TAP aesthetic patients. Outcomes 19 evaluated were the analgesic requirements during the early 20 postoperative days. Fifty-one patients (PB n=27, aesthetic 21 n=24) were assessed. No complications were observed. All 22 PB patients required analgesia until the second postopera- 23 tive day contrarily to most aesthetic ones. Patients with 24 greater flap resected and higher pre-abdominoplasty BMI 25 had greater morphine consumptions. In PB patients, the 26 larger amount of tissues resected corresponded to a greater 27 stimulation of pain fibres that cannot be paralleled by a 28 concomitant increase of the local anesthetic administered. 29 This partially invalidates TAP s efficacy on PB patients. G. Gravante (*) Department of Upper Gastrointestinal Surgery, Frenchay Hospital, Frenchay Park Road, Bristol BS16 1LE, UK ggravante@hotmail.com F. Castrì Clinica Santa Maria di Leuca, Rome, Italy F. Araco Department of Surgery, University Tor Vergata in Rome, Rome, Italy A. Araco Istituto Ninetta Rosano Clinica Tricarico, Marina di Belvedere Marittimo, Marittimo, Italy Keywords Transversus abdominis plane. Pain. Locoregional analgesia. Abdominoplasty. Body contouring. Obesity surgery. Bariatric surgery Introduction The transversus abdominis plane (TAP) block is a technique of locoregional anesthesia recently introduced for procedures that involve the abdominal wall [1]. The local anesthetic is deposited in the plane between the transversus abdominis muscle (TAM) and the internal oblique muscle (IOM), where the sensorial afferent bundles of the nerves T7 to T12 and L1 travel [2 4]. The positive results achieved in different types of surgery in terms of pain relief over the entire anterior abdominal wall and reduction of the analgesia requirements in the early postoperative period [1, 5 11] lead our group to experiment it also on aesthetic abdominoplasty [12, 13]. The results obtained confirmed the dramatic reduction in terms of analgesic drug consumption in the first postoperative day for both morphine and oral opioids. Furthermore, the technique of drug delivery during abdominoplasty is facilitated compared to other operations by the intraoperative exposure of the muscle layers that are directly under visual control of the surgeon. In this view, the technique of drug delivery is not blind nor does it require any intraoperative ultrasound for guidance. Following this path, we decided to evaluate the TAP block efficacy on post-bariatric (PB) abdominoplasty. The beneficial effects of a reduction in the requirements of postoperative morphine could further contribute to make abdominoplasty a less traumatic operation, especially for patients with great amounts of tissue to be resected [14]

2 62 Materials and Methods 63 We retrospectively reviewed notes of all PB patients that 64 underwent PB abdominoplasty and that received the TAP 65 block at the end of surgery to control the postoperative 66 pain. This group was compared with a group of non-pb 67 non-obese patients appropriately matched for age and sex 68 that also received the TAP block in the same period. We 69 excluded those patients that chronically assumed pain 70 killers. 71 Perioperative Analgesic Protocol 72 All patients underwent the same analgesic protocol that was 73 administered by the same anaesthetist. Induction of anes- 74 thesia was conducted with propofol (Diprivan 2 mg/kg), 75 fentanyl (Fentanest 1 mcg/kg) and vecuronium (Norcuron mg/kg), maintenance with a mixture of N 2 O (70%), 77 oxygen (30%) and sevoflurane (Sevorane minimum 78 alveolar concentration = 1.5). The TAP technique has been 79 described previously for aesthetic abdominoplasty [12, 13] 80 and no significant changes were adopted in PB patients. 81 Postoperative analgesia was administered, when required, 82 with morphine (5 10 mg i.m.) in the first postoperative 83 hour and with paracetamol opioid combination tablets (Co- 84 Codamol: Codeine = 30 mg, Paracetamol = 500 mg) 85 afterwards. No patient-controlled analgesia (PCA) was used. 86 Patients free of complications were discharged home after h. 88 For each patient, the following data were recorded: age 89 and sex, height, weight (both before the bariatric surgery 90 and after the weight loss), pre- and PB body mass index 91 (BMI), duration of the operation, amount of flap resected, 92 amount of Bupivacaine used for the block (both as 93 milligrams and millilitres), morphine required in the first 94 postoperative hour (divided between the first half and the 95 second half an hour) and the number of Co-Codamol 96 tablets administered (divided as postoperative hour 2 to 6, 97 7to12,13to24and25to48).Patientsweredefinedas 98 being pain-free when they did not require any analgesic 99 drug. 100 Statistical Analysis 101 All data analysis was performed using the Statistical 102 Package for the Social Sciences Windows version (SPSS, Chicago, IL, USA). Descriptive statistics for 104 quantitative continuous variables were the mean and 105 standard deviation for parametric variables, median and 106 range (minimum and maximum) for non-parametric. Nor- 107 mality assumptions were demonstrated with histograms, 108 Skewness, Kurtosis and Kolmogorov/Smirnov testings. 109 Descriptive statistics for qualitative categorical variables were performed with frequencies. Comparisons of means were conducted with the Student s t test for parametric variables and Mann Whitney for non-parametric ones. Comparison of frequencies with the Chi-square or Fisher s exact test was done when counts in cells were inferior to five. Comparison of non-parametric variables for more than two groups was conducted with the Kruskal Wallis test. Receiver-operating-characteristic (ROC) curves were used to determine the best cut-offs for the flap resected and pre-abdominoplasty BMI predictive of the requirements of analgesia during the first postoperative hour and day. P values were considered significant when inferior to Results Fifty-one patients were eligible for the study. All cases were performed by the first author (A.A.) between March 2009 and January 2010 included with the same surgical technique and the same general anaesthesia. Demographics, clinical characteristics and results obtained are presented in Table 1. No intra- or early postoperative complications related to the anaesthetic, the surgical technique or the TAP block were recorded. All PB patients required analgesia until the second postoperative day, when 81.5% of them became pain-free. Aesthetic patients had significant lower analgesic requirements (Table 1). During the first hour, the median requirement of morphine consisted in 15 mg (10 20 mg) for PB patients, while aesthetic ones that required some were settled with 5 mg. A cut-off of 2,000 g for the flap resected and 29 for the pre-abdominoplasty BMI was determined for patients that required analgesia in the first postoperative hour (area under the curve (AUC) =0.922; Fig. 1) and during the rest of the first day (AUC=0.886; Fig. 1). A subgroup analysis was conducted for PB patients to evaluate any eventual clinical differences according to the amount of morphine required during the first postoperative hour (10, 15 and 20 mg). No significant differences were observed between groups when analysed for pre- and PB BMI, duration of the operation, amount of fat aspirated or amount of Bupivacaine used (Kruskal Wallis test, p=ns). The only parameter that was significant different was the weight of the flap resected: patients with greater flaps resected had higher morphine requirements (Kruskal Wallis test, p=0.01; Fig. 1). The same analysis was conducted according to the number of Co-Codamol tablets required during the first 24 postoperative hours, but no differences were found for all parameters investigated (preand PB BMI, duration of operation, amount of flap resected, amount of Bupivacaine used; Mann Whitney test, p=ns)

3 t1.1 Table 1 Sociodemographic, clinical characteristics and results for patients operated Parameter PB abdominoplasty (N=27) Aesthetic abdominoplasty (N=24) p t1.2 PB post-bariatric Age (years) 44±2 40±2 NS Sex (Females) 22 (81.5%) 24 (100%) NS Height (cm) 167±1 175±1 <0.001 Pre-bariatric weight (kg.) 130±3 Pre-bariatric BMI (kg/m 2 ) 46.8±1 Bariatric operation: Laparoscopic adjustable gastric banding 16 (59.3%) Gastric bypass 9 (33.3%) Sleeve gastrectomy 1 (3.7%) Biliopancreatic diversion 1 (3.7%) Pre-abdominoplasty weight (kg) 94±1 75±2 <0.001 Pre-abdominoplasty BMI (kg/m 2 ) 33.9± ±0.3 <0.001 Operation time (min.) 169±3 118±1 <0.001 Flap weight (gr.) 5635± ±20 <0.001 Fat aspirated (ml.) 420±10 338±13 <0.001 Total Bupivacaine injected: mg 174±6 146±3 <0.001 ml 36±1 28±1 <0.001 Patients requiring analgesia in the first postop. hour 27 (100%) 5 (20.8%) <0.001 Postoperative Morphine requirements (mg) during the 1st hour: 0 mg 0 19 (79.2%) 5 mg 0 5 (20.8%) < mg 5 (18.5%) 0 15 mg 17 (63.0%) 0 20 mg 5 (18.5%) 0 Patients requiring analgesia from hour 2 to (100%) 8 (33.3%) <0.001 Postoperative Co-Codamol requirements (number of tablets) from hour 2 to 24 No tablets 0 16 (66.7%) One tablet 0 6 (25%) Two tablets 1 (3.7%) 2 (8.3%) <0.001 Three tablets 11 (40.7%) 0 Four tablets 13 (48.1%) 0 Five tablets 2 (7.4%) 0 Patients requiring analgesia 2nd postop. day (Co-codamol one tablet) 5 (18.5%) 1 (4.2%) NS t1.3 t1.4 t1.5 t1.6 t1.7 t1.8 t1.9 t1.10 t1.11 t1.12 t1.13 t1.14 t1.15 t1.16 t1.17 t1.18 t1.19 t1.20 t1.21 t1.22 t1.23 t1.24 t1.25 t1.26 t1.27 t1.28 t1.29 t1.30 t1.31 t1.32 t1.33 t1.34 t1.35 t Discussions 161 PB patients that undergo body-contouring abdominoplasty 162 usually have important analgesic requirements. Before the 163 TAP block was introduced in our clinical practice, most PB 164 patients received 5 mg of morphine at the arousal from the 165 anesthesia and another 5 mg in the recovery room, while 166 few of them also asked for an additional 5-mg dose before 167 being transferred to the ward. In the ward, non-tap PB 168 patients received a total of six Co-Codamol tablets for the 169 rest of the first postoperative day and three additional 170 tablets during the second postoperative day. The TAP block has been successful in controlling the early postoperative pain on normal-weight patients undergoing aesthetic abdominoplasty and significantly reduced their analgesic requirements [12, 13]. In the present study, we decided to evaluate the eventual influence of the PB condition on the TAP efficacy through the comparison of a group of TAP- PB patients vs a group of TAP-normal weight aesthetic abdominoplasty. According to our results, the TAP block had a decreased efficacy on PB patients compared to aesthetic abdominoplasty. All PB patients required opioid analgesia until the second postoperative day, when most of them became pain

4 Fig. 1 Left panels: scatter plots showing the relationship between preabdominoplasty BMI and the amount of flap resected divided according to the necessity to administer analgesia in the first postoperative hour (upper panel) and in the rest of the first postoperative day (lower panel). Right panels: box plots showing the relationship between the amount of flap resected and the doses of morphine assumed during the first postoperative hour (upper panel) or the number of Co-Codamol tablets during the first postoperative day (lower panel). Horizontal lines within the box correspond to the median values, boxes to first and third quartiles and vertical lines to the range of values Q3 183 free, while most of the aesthetic patients were pain-free 184 since the first postoperative hour. These negative results of 185 the TAP block are the first compared to previous positive 186 reports on different types of surgery [1, 5 11] and aesthetic 187 abdominoplasty [12, 13]. The strengths of our study consist 188 in the similarities of treatment that patients of both groups 189 received: the same surgeon and anaesthetist operated on all 190 of them, and the same perioperative analgesic protocol, 191 doses and routes of administration were adopted. However, 192 the analysis also showed some important differences 193 between the groups that need to be taken into account when interpreting the results. Although the PB patients decreased in weight, their pre-abdominoplasty BMI was still higher than aesthetic abdominoplasty. However, the Bupivacaine dose administered was also greater in PB patients because the dose per kilogram used was always the same in both groups, reducing the possibility that both these factors could have influenced the results. Similarly, PB operation times were longer than those of aesthetic abdominoplasty for the greater amount of tissues to be removed. Again, in our opinion, this difference cannot justify the difference observed between groups in terms of

5 205 TAP efficacy because the TAP administration was always 206 conducted after the flap resection and prior to the muscles 207 plication. It means that, from this moment onwards, the 208 remaining surgical phases and operating times were similar 209 in both groups with consequently similar temporal onsets of 210 the TAP effects in both groups. 211 The last two significant different parameters were the 212 weight of the flap resected and the amount of fat aspirated. 213 Both could significantly impact the outcomes due to the 214 peculiarities of the PB condition. Greater flaps resected and 215 amounts of fat aspirated correspond to an increased 216 stimulation of the pain fibres that cannot be counter- 217 balanced by a concomitant increase in the total dose of 218 the local anesthetic. This is calculated according to the 219 patient s weight in order to avoid the serious lethal systemic 220 effects of the local anesthetic. However, the peculiar 221 discrepancy between the body weight, dramatically reduced 222 after bariatric surgery, and the amount of tissues to be 223 removed, almost similar to that of an obese patient, 224 probably explains the decreased TAP efficacy in PB vs 225 normal-weight patients. In other words, the amount of local 226 anesthetic that can be safely administered corresponds to that 227 of a normal or pre-obese patient, while the postoperative 228 nociceptic stimulation from the tissues resected and aspirated 229 is similar to that of an obese one. 230 Different options may now be investigated to overcome 231 this issue. We used Bupivacaine, an amidic lipophilic local 232 anesthetic with a high analgesic power, long duration of 233 action (up to 20 hours) and reduced costs. All these 234 characteristics make the drug easily available in our 235 hospital, as well as in other private and public hospitals, 236 for the routine administration on wound incisions at the end 237 of surgery. Bupivacaine has been used for the TAP block 238 according to the manufacturer s recommended doses and 239 did not produce any complications (i.e. cardiotoxicity) or 240 allergies. However, other less cardiotoxic local anesthetics 241 could be evaluated alone or in combination with adrenaline 242 in order to reduce the systemic absorption and eventually 243 increase the TAP efficacy in PB patients. 244 Conclusions 245 Compared to aesthetic abdominoplasties, PB patients seem 246 to gain less from the application of the TAP block in terms 247 of postoperative analgesic requirements. The larger amount 248 of tissues resected correspond to a greater stimulation of 249 pain fibres without any possible concomitant increase in the 303 local anaesthetic total dose. This peculiarity partially invalidates the technique s efficacy in PB patients. However, we still believe that it is worth learning the technique for both the bariatric and the plastic surgeons in order to generate a wider experience and to stimulate future investigations involving different anaesthetics, alone or in combination with adrenaline, in order to overcome this issue. Conflict of interest interest. References The authors declare that they have no conflict of 1. O Donnell BD, McDonnell JG, McShane AJ. The transversus abdominis plane (TAP) block in open retropubic prostatectomy. Reg Anesth Pain Med. 2006;31: Reid SA. The transversus abdominis plane block. Anesth Analg. 2007;105: McDonnell JG, Laffey JG. Transversus abdominis plane block. Anesth Analg. 2007;105: Shibata Y, Sato Y, Fujiwara Y, et al. Transversus abdominis plane block. Anesth Analg. 2007;105: McDonnell JG, O Donnell B, Curley G, et al. 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