IMPACT OF TRENDELENBURG POSITION ON RESPIRATORY MECHANICS IN PEDIATRIC LAPAROSCOPIC SURGERY

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1 IMPACT OF TRENDELENBURG POSITION ON RESPIRATORY MECHANICS IN PEDIATRIC LAPAROSCOPIC SURGERY Victor M. Neira Assistant Professor. Department of Anesthesiology Children's Hospital of Eastern Ontario. University of Ottawa Luis Guerra, Associate Professor - Department of Surgery, Children's Hospital of Eastern Ontario. University of Ottawa Thomas Kovesi, Associate Professor - Department of Pediatrics, Children's Hospital of Eastern Ontario. University of Ottawa Maria Campos, Medical Student - N/A, University of Ottawa Nicholas Barrowman, PhD - Statistics, Children's Hospital of Eastern Ontario Research Institute. William Splinter, M.D.FRCPC. Associate Professor. - Department of Anesthesiology, Children's Hospital of Eastern Ontario. University of Ottawa Introduction: The respiratory effects of the Trendelenburg (head down) position (TDG) during laparoscopic surgery have been well characterized in adults but not in children. General anesthesia with neuromuscular relaxation produces a marked decrease in functional residual capacity (FRC) and lung compliance (LC).(1) Further decrease in FRC and LC occur with the carbon dioxide inducedpneumoperitoneum (PNP) and the TDG required during laparoscopic procedures.(2) Our aim was to describe in detail the changes in respiratory mechanics associated with induced pneumoperitoneum (12 mm Hg pressure) (PNP12) and the Trendelenburg 20 position (TDG20), in pediatric patients undergoing laparoscopic surgery for abdominal cryptorchidism. Methods: The 12 enrolled subjects received pressure control ventilation (PCV) with a positive end expiratory pressure (PEEP) of 5 cm H 2 O and a peak inspiratory pressure (PIP) of cm H 2 O, titrated to achieve a tidal volume (VT/kg) of 6-10 ml/kg, and end-tidal carbon dioxide (EtCO 2 ) of mm Hg. Adjustments of PIP and respiratory rate (RR) were made to maintain VT/kg within 10% of baseline and EtCO 2 <50 mm Hg. Measurements of VT/kg, weight-adjusted dynamic compliance (Cdyn/kg), and EtCO 2 were recorded at baseline, and after PNP12, the first PIP adjustment (Corr1), at TDG20, the second PIP adjustment (Corr2), and after deflation and level positioning, and the final PIP adjustment (Post-deflation corr). Results: PIP was adjusted for all subjects to maintain VT/kg. VT/kg decreased 42 % after PNP12 (baseline: 9.2 ± 1.3ml/kg; PNP12: 5.3 ± 0.7 ml/kg, p<.001). After Corr1 and then TDG20, VT/kg decreased another 10% (to 7.4 ±1.2 ml/kg, p<.04). After deflation, it increased to 13 ml/kg, before being adjusted back to baseline values. Cdyn/kg decreased 43 % after PNP12 (baseline: 0.87 ± 0.21 ml/cmh 2 O/kg; PNP12: 0.50 ± 0.07 ml/cmh 2 O/kg, p<.001) and remained below baseline until deflation. After Corr 1 and TDG20, Cdyn/kg decreased a further 10 % (to 0.51 ± 09 ml/cmh2o/kg, p=.053). Discussion: PNP12 significantly decreases VT/kg and Cdyn/kg in pediatric patients. The use of TDG20 produced a minor impact in respiratory mechanics. This study demonstrates that lung mechanics change significantly during laparoscopic surgery in children, and the need to adjust ventilator settings to maintain normal gas exchange during laparoscopy when using PCV. 1. Anesthesiol. Clin. North America. 2001;19(1): Best Pract. Res. Clin. Anaesthesiol. 2010;24(2):

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3 ULTRASOUND-GUIDED SINGLE INJECTION INFRACLAVICULAR BLOCK VS. ULTRASOUND- GUIDED DOUBLE INJECTION AXILLARY BLOCK: A NONINFERIORITY RANDOMIZED TRIAL Ariane Boivin Anesthesiology Laval University, CHU de Québec Marie-Josée Nadeau - Anesthesiology, CHU de Québec, Hôpital de l'enfant-jésus Simon Lévesque - Anesthesiology, CHU de Québec, Hôpital de l'enfant-jésus Nicolas Dion - Anesthesiology, CHU de Québec, Hôpital de l'enfant-jésus Pierre Nicole - Anesthesiology, CHU de Québec, Hôpital de l'enfant-jésus Alexis Turgeon - Anesthesiology, CHU de Québec, Hôpital de l'enfant-jésus Introduction: Single injection ultrasound-guided infraclavicular block is a simple, reliable and effective technique 1. Recently, a simplified double injection ultrasound-guided axillary block technique has been described with a high success rate 2. The latter is performed in a superficial and compressible location, with thus a potentially improved safety profile. However, its effectiveness in comparison to the single injection infraclavicular block is unknown. We hypothesized that the rate of complete sensory block at 30 minutes with the double injection ultrasound-guided axillary block is noninferior to the single injection ultrasoundguided infraclavicular block. Methods: After local research ethics board approval and informed consent obtained, adults undergoing distal upper arm surgery were randomized to either group I, ultrasound-guided single injection infraclavicular block, or group A, ultrasound-guided double injection axillary block. In group A, 25 ml of mepivacaine 1.5% were injected posteromedial to the axillary artery and 5 ml were injected around the musculocutaneous nerve upon needle retrieval. In group I, 30 ml of mepivacaine 1.5% were injected posteriorly to the axillary artery. The primary outcome was the rate of complete sensory block at 30 minutes. Secondary outcomes were the onset of the block, surgical success rates, performance times and complications. Outcomes were assessed by an investigator unaware of the technique performed. Considering an average rate of complete sensory block of 90% with the single injection infraclavicular block and a noninferiority margin of 10%, 224 patients were required, considering an alpha error or 5% (one-sided hypothesis) and a power of 80%. Results: Both groups of 112 patients each were comparable. At 30 minutes, the rate of complete sensory block was 91% in group I (90% CI: 86%-94%) compared to 79% in group A (90% CI: 72%-84%); the upper limit of group A s confidence interval (84%) is being included in the established noninferiority margin of 10% 3. However, the rate of complete sensory block was lower in group A (p<0.01), as well as the onset of the sensory block (logrank test <0.01). Secondary outcomes are presented in table 1. No complication related to the regional anesthesia technique was noted. Discussion: Based on a noninferiority margin defined at 10%, we cannot exclude that the rate of complete sensory block of the double injection axillary block is noninferior to the single injection infraclavicular block. However, the rate of complete sensory block at 30 minutes is statistically significantly lower with the axillary block and its onset slower. The ultrasound-guided single injection infraclavicular block seems to be the preferred technique for upper arm anesthesia. The double injection axillary block remains an acceptable alternative. 1. Anesth Analg 2009; 109: Reg Anesth Pain Med 2012; 37: JAMA 2012; 308:

4 Table 1. Characteristics of the blocks Group I (n=112) Group A (n=112) p Surgical success, n (%) 104 (93%) 92 (82%) 0,02 Performance time, sec * 200 ( ) 330 ( ) <0,01 Paresthesia, n (%) 11 (10%) 16 (14%) 0,32 Vascular puncture, n (%) 2 (2%) 1 (1%) 0,62 * Median and 25-75% interquartile range

5 INTERPROFESSIONAL PEDIATRIC PAIN EDUCATION IMPACTS PRACTICE Clyde Matava, MD Anesthesia and Pain Management Hospital for Sick Children, Toronto Basem Naser, MD - Anesthesia and Pain Management, Hospital for Sick Children, Toronto Guy Petroz, MD - Anesthesia and Pain Management, Hospital for Sick Children, Toronto Introduction: Effective and timely prevention and relief of pain in children has been identified as a priority in many health institutions across the globe. A multidisciplinary team that includes physicians, nurses, and allied health care providers best provides effective management of pediatric pain. Major limitations for effective pain management include often lack of, and varied quality of knowledge among health care practitioners and inter-professional communication. Methods: Following an in depth needs assessment in June 2012 in a middle eastern country, we utilized an interative process to develop key educational goals adapted for their inter-professional pediatric pain curriculum. To measure the impact of the teaching, we first validated a pediatric pain knowledge and attitude (PPKA) tool for use by physicians. We then progressed to deliver the training over two modules delivered in two days. At the end of training, re-administered the pediatric pain knowledge and attitude tool. To assess retention and knowledge translation, we carried out a followup survey at six months. To enable sustainability of the course we identified key inter-professionals to be trained to take over the course. Results: In the last year, more than 300 physicians, nurses, occupation therapists, physiotherapists, pharmacists have taken the course. Increases in the appropriate knowledge and attitudes to pain in children were detected by the PPKA tool. Key areas of improvement were non-pharmacological interventions with increase in appropriate knowledge and attitudes in the attendees from 30% to 70%. Areas of team work also demonstrated shifts in appropriate attitudes from 15-25% to 74% of the attendees. The six months follow up detected self-reported changes in practice by 80% of course attendees. The key areas with change in practice were early assessment and use of correct pain assessment tools, use of sucrose, multimodal pain management. Areas of continued improvement were team work, need to educate more colleagues. Finally, key individuals were trained to teach the course. Self-reported evaluations from the train the trainer scored 4.1/5 on a scale of 1-5. Conclusion: We report that inter-professional education sensitive to cultural context can result in significant changes in knowledge and attitude of a multi-disciplinary group. Furthermore, changes in practice have also been reported after six months demonstrating a successful translation of knowledge and attitude. 1. Paediatr Child Health February; 12(2): 97 99

6 DEXMEDETOMIDINE RAPID BOLUS DOSE IDENTIFICATION IN CHILDREN Joy Dawes, BSc MBBS MRCP FRCA Department of Anesthesia and Anesthesiology, Pharmacology and Therapeutics BC Children's Hospital and University of British Columbia Dorothy Myers, MSc - Department of Anesthesia and Anesthesiology, Pharmacology and Therapeutics, BC Children's Hospital and The University of British Columbia Matthias Görges, PhD - Department of Electrical and Computer Engineering, The University of British Columbia Guohai Zhou, MSc - Department of Statistics, The University of British Columbia J Mark Ansermino, MBBCh, MSc (Inf), FFA (SA), FRCPC - Department of Anesthesia and Anesthesiology, Pharmacology and Therapeutics, BC Children's Hospital and The University of British Columbia Carolyne J Montgomery, MD - Department of Anesthesia and Anesthesiology, Pharmacology and Therapeutics, BC Children's Hospital and The University of British Columbia Introduction: Dexmedetomidine (DEX) is a highly sensitive and specific alpha-2adrenoceptor agonist with anxiolytic, sedative and analgesic effects. Its use as a perioperative sedative in pediatric anesthesia has increased in the last decade due to the favorable side-effect profile and multitude of clinical applications (1,2). The recommendation is to administer a loading dose as an infusion over a 10 minute period to avoid the hemodynamic effects of hypertension and bradycardia that have been observed following a rapid or large bolus dose (3). However, a previous study suggested that a much shorter time-frame may be used without causing adverse hemodynamic effects (4). The purpose of this study was to determine the dose of DEX that can be given as a rapid bolus over 5 seconds to healthy children during total intravenous anesthesia (TIVA) without causing significant hemodynamic effects. Methods: Research approval was obtained from the institutional Research Ethics Board and Health Canada. Healthy ASA I-II subjects having elective surgery under TIVA using a laryngeal airway device were recruited. Informed written consent from parents/guardians (and assent where appropriate) was obtained. The up-and-down sequential study design (5) was employed to determine the effective dose of DEX which caused no hemodynamic response in half the subjects (ED50). The starting dose was 0.3 mcg/kg with intervals of 0.1 mcg/kg. Positive and negative responses were defined as mean blood pressure (MAP) and heart rate (HR) changes or 30% from baseline. Three parametric estimators and a nonparametric estimator were used to determine the dose (ED50) of 6 pairs of crossovers. Results: 21 subjects (17 males) with median age 7.1 (range ) years and median weight 23.6 (range ) kg were recruited. The 6 th and final crossover was obtained with subject 21. No clinical adverse events were observed. A maximum median HR decrease of 20 beats per minute occurred at 50 seconds and a maximum median MAP increase of 12.5 mmhg occurred at 100 seconds after bolus dose administration (Figure 1). Four estimators led to an ED50 estimate for DEX of 0.50 mcg/kg [95% CI mcg/kg]. Discussion: The bolus dose of DEX (ED50) administered over 5 seconds intravenously without clinically significant hemodynamic compromise in children is 0.50 mcg/kg. Further work is needed to determine the safe (ED5 or less) and effective dose for desired perioperative clinical outcomes. 1. Pediatr Crit Care Med : Paediatr Anaesth : PrecedexTM (dexmedetomidine HCI injection). Available at Accessed 3rd January Anesth Analg : Anesthesiology :144-52

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