Anaesthesiology

Complex effects of continuous vasopressor infusion on fluid responsiveness during liver resection: A preliminary randomised controlled trial BACKGROUND Fluid responsiveness is an important factor to consider for fluid volume loading during major surgery. The effect of continuous vasopressor infusion on fluid responsiveness during prolonged major surgery is a concern. OBJECTIVE We hypothesised that continuous vasopressor infusion during major surgery might not exert significant effects on changes in stroke volume variation (SVV) following fluid bolus infusion, and thereby on fluid responsiveness. DESIGN Randomised controlled trial. SETTING University hospital from April 2014 to August 2016. PATIENTS Patients undergoing liver resection who were randomised to receive continuous intravenous infusion of phenylephrine (P group), norepinephrine (N group), or no vasopressor (C group) (n=17/group). Exclusion criteria were cardiac arrhythmia and severe cardiac, pulmonary or renal dysfunction. INTERVENTION Patients received 4 ml kg−1 fluid boluses of 6% hydroxyethyl starch solution when SVV was at least 12%. Vasopressors were administered continuously to maintain the systemic vascular resistance index at more than 1900 dyn s cm−5 m−2. MAIN OUTCOME MEASURES Cardiac index and SVV were measured using the FloTrac™/Vigileo™ system (Version 4.00). The number of fluid boluses with fluid responsiveness (i.e. >15% increase in cardiac index) was compared between groups using multilevel logistic regression analysis. RESULTS Numbers of fluid responsive boluses in the C, P and N groups were 12 (14%), 22 (34%) and 19 (27%), respectively. Odds ratios on fluid responsiveness for phenylephrine and norepinephrine compared with the control were 3.65 (97.5% confidence interval, 1.15 to 11.6; P = 0.012) and 2.56 (97.5% confidence interval, 0.82 to 8.00; P = 0.064), respectively. Decreases in SVV after fluid bolus infusion for the P and N groups were comparable with the C group (P = 0.23 and 0.53, respectively). CONCLUSION Continuous administration of phenylephrine increased fluid responsiveness during liver resection, suggesting complex effects of continuous vasopressor infusion involving changes in cardiac preload and afterload. TRIAL REGISTRATION UMIN000011024. Correspondence to Tsuneo Tatara, MD, Department of Anaesthesiology and Pain Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya 663-8501, Hyogo, Japan Tel: +81 798 45 6392; fax: +81 798 45 6393; e-mail: ttatara@hyo-med.ac.jp © 2019 European Society of Anaesthesiology

Effectiveness of a visual noise warning system on noise levels in a surgical ICU: A quality improvement programme BACKGROUND The effects of noise are harmful to patients in the ICU environment, and the latter are particularly noisy places. High noise levels seem to be a factor in sleep disturbance, which can, in turn, result in increased morbidity. LOCAL PROBLEM High noise levels are a recognised problem in ICUs worldwide. OBJECTIVE(S) The goal was to estimate the effect of a visual noise-warning system on noise levels in a surgical ICU before and after its implementation. DESIGN A quality improvement initiative. SETTING A 12-bedded surgical ICU in a tertiary care university hospital. PATIENTS A total of 148 adult nonintubated and nonsedated patients completed the study, during a 6-week period. INTERVENTION Noise levels were continuously recorded using a Type II sound level meter for 6 weeks. The study was divided into three phases. The first 2 weeks, baseline noise levels were measured (phase I). In week 3 of the study, a visual noise warning system (SoundEar II) that changed colour depending on noise levels within the ICU was installed and implemented (phase II). The alarm system was set to light up green at levels below 55 dBA, orange at levels between 55 and 60 dBA and red at levels above 60 dBA. The device was switched off at the beginning of week 5 and the sound level meter continued recording noise levels for another 2 weeks (phase III). RESULTS Mean night-time noise level was 55.98 dBA in the preintervention phase, 54.14 dB during the intervention, and 54.98 dBA in the postintervention phase. Mean noise level was reduced statistically significantly by 1.35 dBA, and there was a sustained reduction of 0.86 dBA from the baseline noise level 2 weeks after SoundEar II was switched off. CONCLUSION Visual noise warning systems can be effective in achieving a reduction in noise levels in critical care units. Correspondence to Miriam de Nadal, Department of Anesthesiology and Intensive Care, Hospital Universitari Vall d'Hebron, Ps Vall d'Hebron 119-129, 08035 Barcelona, Spain Tel: +34 932746004; e-mail: minadal@vhebron.net © 2019 European Society of Anaesthesiology

Comparison between the new fully automated viscoelastic coagulation analysers TEG 6s and ROTEM Sigma in trauma patients: A prospective observational study BACKGROUND Viscoelastic coagulation testing is increasingly used to diagnose trauma-induced coagulopathy. Two fully automated analysers, TEG 6s and ROTEM Sigma, were launched recently. No previous studies have compared these devices in trauma paients. OBJECTIVE The aim of this study was to evaluate whether both fully automatic devices deliver comparable results. DESIGN Prospective observational study. SETTING Level one trauma centre from August 2017 to September 2018. PATIENTS A total of 105 blood samples from 67 trauma patients were analysed simultaneously on TEG 6s and ROTEM Sigma. MAIN OUTCOME MEASURES TEG 6s assays kaolin (CK), RapidTEG (CRT), kaolin with heparinase (CKH) and functional fibrinogen were compared with ROTEM Sigma assays INTEM, EXTEM, HEPTEM and FIBTEM. TEG 6s functional fibrinogen level was compared with plasma fibrinogen concentration, measured using the Clauss method. Correlations were classified as weak (Spearman correlation coefficient 0.20 to 0.39), moderate (0.40 to 0.59), strong (0.60 to 0.79) or very strong (≥0.80). RESULTS The TEG 6s parameters reaction time, kinetic time and α-angle (CK, CRT and CKH assays) mostly showed strong correlations with the corresponding ROTEM parameters clotting time, clot formation time and α-angle (INTEM, EXTEM and HEPTEM assays). The exceptions were CRT reaction time vs. EXTEM clotting time, and CK α-angle vs. INTEM α-angle, which correlated moderately. Absolute values for many of these parameters showed significant differences between the two devices. Very strong correlations and similar absolute values were observed between TEG 6s maximum amplitude (CRT, CK and CKH assays) and ROTEM maximum clot firmness (EXTEM, INTEM and HEPTEM assays). Correlations were also very strong for functional fibrinogen maximum amplitude vs. FIBTEM maximum clot firmness and functional fibrinogen level vs. Clauss fibrinogen concentration, but absolute values were significantly different. CONCLUSION Strong to very strong correlations were observed between corresponding TEG 6s and ROTEM Sigma parameters. However, absolute values showed significant differences for most of the measurements. Correspondence to Herbert Schöchl, MD, Department of Anaesthesiology and Intensive Care Medicine, AUVA Trauma Centre Salzburg, Academic Teaching Hospital of the Paracelsus Medical University, Dr Franz Rehrl Platz 5, 5020 Salzburg, Austria; Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, AUVA Trauma Research Centre, Vienna, Austria E-mail: herbert.schoechl@auva.at Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (www.ejanaesthesiology.com). © 2019 European Society of Anaesthesiology

A systematic review of randomised controlled trials investigating prehabilitation before major intra-abdominal cancer surgery: An analysis of prehabilitation content and outcome measures BACKGROUND Although prehabilitation programmes for patients undergoing major intra-abdominal cancer surgery have been shown to improve pre-operative physical fitness, the conclusions regarding any postoperative benefits are inconsistent. OBJECTIVES The aim of this study was to evaluate the content of and the outcome measures used in studies of prehabilitation programmes for these patients. It was hypothesised that the content of prehabilitation programmes is often therapeutically invalid, and that the postoperative outcomes assessed are inadequate to evaluate the impact of complications. DESIGN A systematic review of randomised controlled trials. DATA SOURCES Studies published between January 2009 and January 2019 were retrieved from PubMed, Embase and PEDro. ELIGIBILITY CRITERIA Studies were included when they investigated the effects of prehabilitation in patients undergoing intra-abdominal surgery for cancer, reported pre-operative and/or postoperative outcome measures and were conducted as a randomised controlled trial. Studies for which the full text was not available were excluded, as were studies of patients undergoing nonabdominal cancer surgery. RESULTS Eight studies (565 patients) were included. Therapeutic validity was low in five studies. Most studies included low-risk surgical patients and considerable variation was observed between prehabilitation programmes in terms of supervision, training context, frequency, intensity, duration and training type. Objective monitoring of training progression was typically not performed, and most trials did not include nutritional or psychological support. Postoperative complications were reported in seven studies, but no study reported the impact of postoperative complications, nor on long-term postoperative outcomes. CONCLUSION The content of prehabilitation programmes was heterogeneous. Studies with a high therapeutic validity found unequivocal evidence that prehabilitation had beneficial effects on postoperative outcomes. Future research should focus on adequate selection and inclusion of high-risk surgical patients and provide personalised and probably multimodal (partly) supervised prehabilitation, with objective monitoring of progress. Measuring the incidence and impact of postoperative complications may contribute to demonstrating the clinical value of prehabilitation. This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0 Correspondence to Bart C. Bongers, PhD, Maastricht University, Department of Nutrition and Movement Sciences, P.O. Box 616, 6200 MD Maastricht, The Netherlands Tel: +0031433882236; e-mail: bart.bongers@maastrichtuniversity.nl Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (www.ejanaesthesiology.com). © 2019 European Society of Anaesthesiology

Ultrasound-assisted vs. landmark-guided paramedian spinal anaesthesia in the elderly: A randomised controlled trial BACKGROUND Neuraxial ultrasound might improve the efficacy of spinal anaesthesia but this has not been tested for the paramedian approach in the elderly. OBJECTIVE The current study aims to assess whether the ultrasound-assisted paramedian technique can decrease the number of needle passes required for success compared with the landmark-guided paramedian technique in the elderly. DESIGN Prospective randomised controlled study. SETTING Single-institution, tertiary-level hospital in Seoul, Republic of Korea from October 2017 to January 2018. PATIENTS Eighty patients aged at least 60 years undergoing orthopaedic surgery. INTERVENTION All received paramedian spinal anaesthesia by either the landmark-guided or preprocedural ultrasound-assisted technique. MAIN OUTCOME MEASURES The number of needle passes required for successful dural puncture. RESULTS The number of needle passes (median [interquartile range]) was significantly lower (1.0 [1.0 to 2.0] vs. 4.5 [2.0 to 7.0]) and the success rate at first pass significantly higher at 65.0 vs. 17.5% in the ultrasound compared with the landmark group (both P < 0.001). The ultrasound-assisted technique required a longer time for establishing landmarks 117.5 [85.5 to 150.7] vs. 17.5 [14.0 to 23.0] s, and for total procedure 181.5 [133.5 to 212.5] vs. 92.5 [62.5 to 176.5] s, but a shorter time for administering spinal anaesthesia 39.5 [31.5 to 71.3] vs. 77.0 [45.8 to 136.5] s (all P < 0.001) than the landmark-guided technique. The ultrasound group showed lower periprocedural pain scores 3 [2 to 4] vs. 4 [4 to 6] (P = 0.009) and discomfort scores 2 [0 to 3] vs. 5 [2 to 6] (P = 0.003) than the landmark group. CONCLUSION Compared with the landmark-guided paramedian technique, the ultrasound-assisted paramedian technique decreases the number of needle manipulations and periprocedural pain and discomfort scores in the elderly. Our results suggest that neuraxial ultrasonography facilitates the performance of spinal anaesthesia in the elderly. TRIAL REGISTRATION NCT03316352. Correspondence to Jin-Tae Kim, Department of Anesthesiology and Pain Medicine, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Republic of Korea E-mail: jintae73@gmail.com Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (www.ejanaesthesiology.com). © 2019 European Society of Anaesthesiology

Bilateral subcostal transversus abdominis plane block does not improve the postoperative analgesia provided by multimodal analgesia after laparoscopic cholecystectomy: A randomised placebo-controlled trial BACKGROUND Laparoscopic cholecystectomy might be considered minor surgery, but it may result in severe postoperative pain. Subcostal transversus abdominis plane (TAP) block, which produces long-lasting supra-umbilical parietal analgesia, might improve analgesia after laparoscopic cholecystectomy. OBJECTIVE We investigated whether subcostal TAP block would reduce opioid consumption and pain after laparoscopic cholecystectomy in patients provided with multimodal analgesia. DESIGN A randomised, placebo-controlled, double-blind study. SETTING The study was conducted at a university teaching hospital from December 2017 to June 2018. PATIENTS Sixty patients scheduled for laparoscopic cholecystectomy were included. Anaesthesia and postoperative analgesia (etoricoxib, paracetamol, ketamine and dexamethasone) were standardised. INTERVENTION After induction of anaesthesia, patients were allocated into two groups: ultrasound-guided bilateral subcostal TAP block with 20 ml of levobupivacaine 0.375% and epinephrine 5 μg ml−1 or 0.9% saline with epinephrine 5 μg ml−1. MAIN OUTCOME MEASURES Opioid consumption in the recovery room and during the first 24 h after surgery were recorded. Postoperative somatic and visceral pain scores, fatigue and nausea were measured. Intra-operative end-tidal concentrations of sevoflurane (FETSEVO) were also recorded. RESULTS Twenty-four hour postoperative opioid consumption were similar in both groups: 21.2 mg (95% CI 15.3 to 27.1) vs. 25.2 (95% CI 15.1 to 35.5) oral morphine equivalent in the levobupivacaine and 0.9% saline groups, respectively; P = 0.48. No significant between-group differences were observed with regards to parietal (P = 0.56) and visceral (P = 0.50) pain scores, fatigue and nausea. FETSEVO was slightly lower in the levobupivacaine group (P < 0.01). CONCLUSION Subcostal TAP block does not improve the analgesia provided by multimodal analgesia after laparoscopic cholecystectomy. It allows for a small reduction in intra-operative sevoflurane requirements. CLINICAL TRIAL REGISTRATION NCT0339153 Correspondence to Jean L. Joris, MD, PhD, Department of Anaesthesiology, CHU Liège, Domaine du Sart Tilman, Avenue de l'hôpital Bat B35, Liège B-4000, Belgium. Tel: +32 4 3667180; fax: +32 4 3667636; e-mail: jean.joris@chuliege.be © 2019 European Society of Anaesthesiology

Effects of goal-directed crystalloid vs. colloid fluid therapy on microcirculation during free flap surgery: A prospective randomised clinical trial BACKGROUND Macro, and microcirculatory effects of crystalloids and colloids are difficult to compare, because interventions to achieve haemodynamic stability seldom follow similar criteria. OBJECTIVES Our aim was to compare the effects of crystalloids and colloids on the microcirculation during free flap surgery when management was guided by detailed haemodynamic assessment. DESIGN A prospective randomised, controlled clinical trial. SETTINGS The investigation was performed at the University of Szeged, Hungary. PATIENTS Patients undergoing maxillofacial tumour resection and free flap reconstruction were randomised into groups treated with either intra-operative crystalloid (Ringerfundin, n = 15) or colloid (6% hydroxyethyl starch, HES, n = 15) solutions. INTERVENTIONS Macrohaemodynamics were monitored by a noncalibrated device (PulsioFlex-PULSION). Central venous oxygen saturation, venous-to-arterial PCO2-gap, lactate levels and urine output were measured hourly. Maintenance fluid was Ringerfundin (1 ml kg−1 h−1), and a multimodal, individualised, approach-based algorithm was applied to guide haemodynamic support. Hypovolaemia was treated with Ringerfundin or HES fluid boluses, respectively. The microcirculatory effects were assessed by laser-Doppler flowmetry (PeriFlux 5000 LDPM), with the probe placed on the flap and on a control area. Measurements were performed after the flap was prepared, then 1 and 12 h later. MAIN OUTCOME MEASURES The primary end-point was microcirculatory perfusion as determined by laser-Doppler flowmetry. RESULTS There was no difference between the groups regarding patient characteristics. Both groups remained haemodynamically stable throughout due to the use of approximately a 1.5 times higher total fluid volume in the Ringerfundin group than in the HES group: mean ± SD: 2581 ± 986 and 1803 ± 497) ml, respectively, (P = 0.011). There was no significant difference in the microcirculatory blood flow between the groups. CONCLUSION Our results showed that when fluid management was guided by detailed haemodynamic assessment, more crystalloid than colloid was needed to maintain haemodynamic stability, but there was no difference between the effects of crystalloids and colloids on the microcirculation. TRIAL REGISTRATION ClinicalTrials.gov (NCT03288051). Correspondence to Ildikó László, Department of Anaesthesiology and Intensive Therapy, University of Szeged, 6 Semmelweis St., Szeged 6725, Hungary; E-mail: laszlo.ildiko@med.u-szeged.hu © 2019 European Society of Anaesthesiology

Allogeneic red cell transfusion and its influence on relevant humoral and cellular immunological parameters: A prospective observational trial BACKGROUND It is assumed that transfusion of allogeneic red cells is associated with increased peri-operative mortality and morbidity. Also assumed is the theory of transfusion-related immunomodulation. OBJECTIVE The aim of this study was to investigate the hypothesis that red cell transfusion specifically leads to an immunological response in surgical patients. DESIGN Prospective observational study. SETTING Departments of Orthopedic Surgery and Anaesthesia, University Hospital, Thailand. PATIENTS Low-risk, noncancer patients, aged 18 to 75 years undergoing elective major spine surgery, with and without red cell transfusion therapy. INTERVENTIONS Blood specimens were withdrawn four times (prior to surgery and on days 1, 3 and 5). MAIN OUTCOME MEASURES Assessment of immunocompetent cells and cytokines in transfused and nontransfused patients using flow cytometry and multiplex ELISA. RESULTS From a total of 78 patients, 61 met the requirements and were analysed in three groups: 19 with no transfusion and 26 and 16 transfused intra-operatively and on day 1 or 2, respectively. No patient experienced peri-operative haemorrhage. Postoperative infection or thrombosis occurred in 5.5% of nontransfused patients and 16.6% of transfused patients; the difference was not significant. There was no significant immunomodulatory effect of red cell transfusion: of 45 immunological parameters, only five little-relevant cytokines were significantly affected, although slightly and nonspecifically. CONCLUSION Our data indicate that red cell transfusion alone does not create an immunological response in otherwise healthy surgical patients. Our findings do not generally contradict the transfusion-related immunomodulation phenomenon, which has, however, primarily been observed in patients with an already weakened or procedure-deteriorated immune system, such as from malignant disease, significant comorbidity, extensive abdominal/thoracic surgery and cardiopulmonary bypass. TRIAL REGISTRATION The study was registered on 15 May 2014, before enrolment of the first patient, at www.ClinicalTrials.gov, NCT02140216. Correspondence to Benno von Bormann, Department of Anesthesiology, Faculty of Medicine, Siriraj Hospital, Mahidol University, 2 Wanglang Road, Bangkok 10700, Thailand Tel: +66 918825723/+66 24197990; e-mail: bvb@jodu.de © 2019 European Society of Anaesthesiology

Effect of positive end-expiratory pressure on gastric insufflation during induction of anaesthesia when using pressure-controlled ventilation via a face mask: A randomised controlled trial BACKGROUND Face mask ventilation (FMV) during induction of anaesthesia is associated with risk of gastric insufflation that may lead to gastric regurgitation and pulmonary aspiration. A continuous positive airway pressure (CPAP) has been shown to reduce gastric regurgitation. We therefore hypothesised that CPAP followed by FMV with positive end-expiratory pressure (PEEP) during induction of anaesthesia would reduce the risk of gastric insufflation. OBJECTIVE The primary aim was to compare the incidence of gastric insufflation during FMV with a fixed PEEP level or zero PEEP (ZEEP) after anaesthesia induction. A secondary aim was to investigate the effects of FMV with or without PEEP on upper oesophageal sphincter (UES), oesophageal body and lower oesophageal sphincter (LES) pressures. DESIGN A randomised controlled trial. SETTING Single centre, Department of Anaesthesia and Intensive Care, Örebro University Hospital, Sweden. PARTICIPANTS Thirty healthy volunteers. INTERVENTIONS Pre-oxygenation without or with CPAP 10 cmH2O, followed by pressure-controlled FMV with either ZEEP or PEEP 10 cmH2O after anaesthesia induction. MAIN OUTCOME MEASURES A combined impedance/manometry catheter was used to detect the presence of gas and to measure oesophageal pressures. The primary outcome measure was the cumulative incidence of gastric insufflation, defined as a sudden anterograde increase in impedance of more than 1 kΩ over the LES. Secondary outcome measures were UES, oesophageal body and LES pressures. RESULTS The cumulative incidence of gastric insufflation related to peak inspiratory pressure (PIP), was significantly higher in the PEEP group compared with the ZEEP group (log-rank test P < 0.01). When PIP reached 30 cmH2O, 13 out of 15 in the PEEP group compared with five out of 15 had shown gastric insufflation. There was a significant reduction of oesophageal sphincter pressures within groups comparing pre-oxygenation to after anaesthesia induction, but there were no significant differences in oesophageal sphincter pressures related to the level of PEEP. CONCLUSION Contrary to the primary hypothesis, with increasing PIP the tested PEEP level did not protect against but facilitated gastric insufflation during FMV. This result suggests that PEEP should be used with caution after anaesthesia induction during FMV, whereas CPAP during pre-oxygenation seems to be safe. TRIAL REGISTRATION ClinicalTrials.gov, identifier: NCT02238691. This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0 Correspondence to Per Cajander, Department of Anaesthesia and Intensive Care Örebro University Hospital, Södra Grev-Rosengatan, 701 85, Örebro, Sweden Tel: +46 19 602 03 53; e-mail: per.cajander@regionorebrolan.se © 2019 European Society of Anaesthesiology

Effect of sevoflurane-based or propofol-based anaesthesia on the incidence of postoperative acute kidney injury: A retrospective propensity score-matched analysis BACKGROUND Propofol may help to protect against ischaemic acute kidney injury (AKI); however, research on this topic is sparse. OBJECTIVE The current study aimed to investigate whether there were differences in the incidence of postoperative AKI after lung resection surgery between patients who received propofol-based total intravenous anaesthesia (TIVA) and those who received sevoflurane-based inhalational anaesthesia. DESIGN A retrospective observational study. SETTING A single tertiary care hospital. PATIENTS Medical records of patients aged 19 years or older who underwent curative lung resection surgery for nonsmall cell lung cancer between January 2005 and February 2018 were examined. MAIN OUTCOME MEASURES After propensity score matching, the incidence of AKI in the first 3 postoperative days was compared between patients who received propofol and those who received sevoflurane. Logistic regression analyses were also used to investigate whether propofol-based TIVA lowered the risk of postoperative AKI. RESULTS The analysis included 2872 patients (1477 in the sevoflurane group and 1395 in the propofol group). After propensity score matching, 661 patients were included in each group; 24 (3.6%) of the 661 patients in the sevoflurane group developed AKI compared with 23 (3.5%) of the 661 patients in the propofol group (95% confidence intervals of difference in incidence −0.019 to 0.022, P = 0.882). The logistic regression analyses revealed that the incidence of AKI was not different in the two groups (odds ratio 0.96, 95% confidence interval 0.53 to 1.71, P = 0.882). CONCLUSION In this retrospective study, no significant difference was found in the incidence of postoperative AKI after lung resection surgery between patients who received propofol-based TIVA and those who received sevoflurane-based inhalational anaesthesia. Considering the methodological limitation of this retrospective study, further studies are required to confirm these results. Correspondence to Tak Kyu Oh, Department of Anesthesiology and Pain Medicine, Seoul National University Bundang Hospital, 166, Gumi-ro, Bundang-gu, Seongnam-si 13620, Gyeonggi-do, South Korea Tel: +82 31 787 7501; fax: +82 31 787 4063; e-mail: airohtak@hotmail.com Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (www.ejanaesthesiology.com). © 2019 European Society of Anaesthesiology

Alexandros Sfakianakis
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