Can J Anesth/J Can Anesth (2014) 61:S1–S165 DOI 10.1007/s12630-014-0239-1

33101 - RANDOMIZED PROSPECTIVE TRIAL COMPARING TWO SUPRAGLOTTIC AIRWAY DEVICES: I-GEL™ AND LMA- SUPREME™ IN PARALYZED PATIENTS Author(s) François Donati Anesthesiology Université de Montréal, Hôpital Maisonneuve-Rosemont Role: Presenting Author Louis-Pierre Poulin Anesthesiology Université de Montréal Role: Primary Author Co-Author(s) Nikola Joly - Anesthesiology, Université de Montréal, Centre Hospitalier Universitaire de Montréal (CHUM), Division hôpital Saint-Luc Issam Tanoubi - Anesthesiology, Université de Montréal, Hôpital Maisonneuve-Rosemont Pierre Drolet - Anesthesiology, Université de Montréal, Hôpital Maisonneuve-Rosemont Introduction: Many features can influence the choice of a supraglottic airway device (SAD) such as the ease of insertion, adequate ventilation pressures and lack of adverse effects. The goal of this randomized prospective trial was to evaluate the performance of the I-gel™ and the LMA-Supreme™. Methods: One hundred adult patients (ASA I-III) scheduled to undergo elective surgery under general anesthesia were randomized either to an I-gel™ (n=50) or an LMA-Supreme™ (n=50). The primary objective was to compare ventilation pressures. Secondary objectives included time and number of trials needed to introduce the device, adverse effects and repositioning. Endoscopic view of the glottic aperture and position of the drain tubes with regard to the oesophagus were also evaluated. Results: Both devices were inserted successfully in 46 (92%) patients in both groups. There was no significant difference in the leak pressure (I-gel™: 23 + 7 vs. LMA-Supreme™: 21 + 8 cmH2O; P = 0.14) or peak inspiratory pressure between both devices. Insertion time was shorter with the I-gel™ than with the LMA-Supreme™ (19 ± 7 vs. 27 ± 17 s; P = 0.003). The vocal cords were completely visualized more often through the I-gel™ (70%) than through the LMA-Supreme™ (50%) (P = 0.007). Oesophageal mucosa was easily visualized through the drain port in all patients but four, two in each group. There was no difference between groups regarding peroperative or postoperative complications. Postoperative patient discomfort was generally mild and comparable for both devices. Conclusion: Both the LMA-Supreme™ and the I-gel™ offer similar performance for positive pressure ventilation during general anesthesia. The I-gel™ was associated with a faster insertion time and better fiberscopic visualization of the glottis, suggesting a more optimal alignment between the SAD and ventilatory stuctures. Registered clinical trial: Clinicaltrials.gov reference number NCT01001078 References: Anaesthesia. 66(6):481-7. 2011 Anaesthesia. 65(12): 1173-9. 2010 Anaesth and Intensive Care. 38(6): 1018-22. 2010 BMC Anesthesiology. 12:18. 2012 British Journal of Anaesthesia. 109 (6): 996–1004. 2012 Anesth Analg. 114(1): 152-6. 2012

© Canadian Anesthesiologists’ Society 2014

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33356 - A MOBILE DEVICE APPLICATION: CALCULATIONS TO MANAGE OBESE PATIENTS Author(s) John H P. Friesen Anesthesia and Perioperative Medicine University of Manitoba Role: Primary & Presenting Author Introduction: Mobile devices, including smart phones and tablets, are ubiquitous in the operating room and they have become essential point of care anesthesia equipment(1,2). They are also increasingly important as educational tools (3). Following is a description of a mobile application that performs and documents calculations used in the safe anesthetic management of obese patients(4). It demonstrates an approach to the design of a useful, safe, and reliable cognitive aid. Methods: Clinically important formulas were chosen from three areas of interest: weight scalars, blood volumes, and risk for obstructive sleep apnea. Mathematical functions were coded in JavaScript, and the user interface was written using CSS and active HTML5. The display was optimized for use on smart phones and tablets. To create an app suitable for installation on mobile devices, the program was then compiled using Adobe PhoneGap Build. Results: The Figure is a screenshot of the Blood Volumes display screen. The “Menu” and “Input” buttons navigate to the application’s menu screen and data input form respectively. Touching the “Info” button displays information about the formulas and lists relevant references. Patient data required for the calculations are shown beneath the navigation bar, and below that the calculated values are displayed. The Weight Scalars screen uses a similar layout with identical navigation buttons. The OSA Risk screen presents an interactive Stop-Bang questionnaire, again with an “Info” button to show references and discussion. Discussion: Obesity is a common and challenging perioperative problem(5). It lends itself to the use of a cognitive aid because of the quantitative and mathematical nature of many of its effects on anesthetic technique and safety. A point of care app can improve patient safety and promote efficiency by eliminating the need to estimate several different quantities for each patient. The app can perform all the computations with a single button press, and the output will then remain available for the duration of the case. To be useful, an app must provide evidence of accuracy and reliability(6). In this case, references to the medical literature are given for each formula or score. Primary sources document the original descriptions. Selected secondary sources provide an entry to the literature and facilitate critical appraisal of the available evidence. The app described here demonstrates a number of calculations used in the anesthetic management of obese patients. It is clinically useful for patient management in the operating room, and is also designed to act as a learning tool for students and residents. References: 1. Anaesthesia. 2011 66: 630-1 2. Postgrad Med J 2013 doi:10.1136/postgradmedj-2013-131930 3. Best Pract Res Clin Anaesthesiol 2012 26: 33-53 4. www.bigsleep.altervista.org 5. Can J Anesth 2012 59: 974-96 6. J Physician Assist Educ 2013 24: 38-40

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33770 - A RANDOMIZED TRIAL OF AMITRIPTYLINE VERSUS GABAPENTIN FOR NEUROPATHIC PAIN IN CHILDREN Author(s) Stephen C. Brown, MD FRCPC The Hospital For Sick Children Role: Primary & Presenting Author Co-Author(s) Khush Amaria, PhD - Division of Adolescent Medicine, The Hospital for Sick Children Fiona Campbell, MD FRCA - Dept of Anesthesia and Pain Medicine, The Hospital for Sick Children Bradley Johnston, PhD - Dept of Anesthesia and Pain Medicine, The Hospital for Sick Children Patricia McGrath, PhD - Dept of Anesthesia and Pain Medicine, Pain Innovations Inc Introduction: Treatment of neuropathic pain and complex regional pain syndrome requires a multimodal approach of pharmacologic, physical, and psychological therapies. While amitriptyline and gabapentin are our front line drugs for treating neuropathic pain, no studies have yet compared them directly to determine which drug might be better for relieving pain, disability and sleep disturbances(1,2).Our primary study objective was to compare the efficacy of gabapentin and amitriptyline for treating neuropathic pain in children in a randomized controlled trial (RCT). Secondary objectives were to evaluate changes in children’s disability and sleep. Methods: REB ethical approval was obtained prior to study initiation and patient consent/ascent was obtained prior to commencemnt of each drug trial. Eligible participants ranged from 8 to 17 years of age. Diagnosis of neuropathic pain (pre 2011 NP classification) was made at The Hospital for Sick Children’s Chronic Pain Clinic. Electrocardiograms were performed on all patients prior to study to rule out conduction abnormalities. Patients were prescribed a regimen of pharmacologic, physical, and psychological therapy. Patients received either gabapentin (300 mg tid) or amitriptyline (10 mg qhs) with capsules matched for size and dosing regimen matched with appropriate placebos for a 6week, triple-blind (patient, physician, data analyst) RCT. Patients completed weekly interviews to obtain outcomes and attended an in-hospital interview at 6 weeks. Primary outcome was a change in usual (i.e., past week) pain intensity from baseline to 6-weeks as measured by an 11-point Colored Analog Scale (3). Results: Thirty-four patients (82% female) were randomized to amitriptyline or gabapentin. Two patients allocated to the amitriptyline group were ineligible due to a contraindicated condition identified at start of trial. Three participants were discontinued from gabapentin and amitriptyline groups (2 and 1, respectively) due to adverse events deemed unrelated to study medications. The primary analysis was based on 29 patients having completed the study. Mean pain intensity at baseline was comparable for 2 groups: 6.5±1.4 for amitriptyline and 5.3±2.6 for gabapentin. At the end of the 6-week trial, mean usual pain intensity was 5.0±3.0 for amitriptyline (a difference of -1.5 from baseline) and 3.3±2.4 for gabapentin (a difference of -2.0 from baseline). Usual pain scores did not differ significantly between groups (p > .05, independent sample t-tests). Discussion: Based on our data, our standard dose of amitriptyline and gabapentin are effective in reducing usual pain intensity ratings in a 6 week trial for children and adolescents with neuropathic pain. References: 1. Dworkin et al (2010). Recommendations for the pharmacological management of neuropathic pain: an overview and literature update. Mayo Clinic Proceedings, Mar;85(3 Suppl):S3-14. 2. IASP (2010) Pharmacological Management of Neuropathic Pain. Pain Clinical Updates, Vol. XVIII, Issue 9. 3. McGrath PA, Seifert CE, Speechley KN, Booth JC, Stitt L, Gibson MC. A new analogue scale for assessing children’s pain: an initial validation study. Pain. 1996; 46:435-443.

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33877 - ULTRASONOGRAPHY FOR URGENT VISUALIZATION OF SPINAL CANAL ANATOMY Author(s) Muhammad Ajmal, MBBS, DA Dept. of Anesthesia, Coombe Women and Infants University Hospital, Dublin, Ireland Role: Primary & Presenting Author Disclosure: Co-Author(s) John Loughrey, FFARCSI – Dept. of Anesthesia, Rotunda Hospital, Dublin, Ireland Introduction: This is something the experts may disagree upon whether reassuring sonoanatomy of 1, 2 the spinal canal is enough to warrant epidural placement when a patient gives a history of spinal 3 canal problem such as spina bifida occulta in an acute care setting? Spina bifida occulta although is not a contraindication for epidural placement but enhances the risk of inadvertent dural puncture or neurological injury in case of a tethered spinal cord. In this case report we highlight the role of ultrasonographic images to facilitate decision making for epidural placement in an obstetric acute care setting where a woman provided a history of spina bifida occulta. Case description: A 33-year-old primigravida requested analgesia for her labor pains. Her labor was anticipated to be highly painful and prolonged. Augmentation of labor with oxytocin was planned. There were no clinical abnormalities present, but based on a lumbosacral radiograph taken 10-year prior, the patient had provided a history of spina bifida occulta during her antenatal visit. Although an anesthesia-clinic appointment was scheduled for assessment, she missed that appointment and now presented in labor to the labor ward. At this stage, an urgent radiological assessment of her vertebral canal was not possible. Remifentanil patient-controlled-analgesia (PCA) could have been available but given the parturient’s characteristics, epidural analgesia was the best choice of treatment for her. After discussing the case and having obtained written informed-consent, an ultrasonographic assessment of her lumbosacral vertebral canal was performed. The sonoanatomy in “paramedian sagittal oblique” plane showing lumbar vertebral arches and in “transverse median” plane showing thecal sac (1& 2 in Fig. A) was essentially normal. The depth of epidural space from the intended skin puncture point at L4 – L 5,measured using ultrasonography, was 3.95 cm. An epidural catheter was placed at L4-L5 using 18 G Tuohy needle; the loss of resistance was encountered at 4 cm from skin and 5 cm of the catheter was left in the epidural space. The epidural analgesia was effective and did not cause any adverse consequences. Two months later, the only abnormality involved prominent degenerative changes at L5-S1 with a moderate-sized broad-based disc bulge that was abutting the thecal sac centrally [1, Fig. B]. A follow-up magnetic resonance imaging (MRI) [Fig. B] revealed lumbosacral transitional anatomy (lumbarization of S1) and no spina bifida occulta. Discussion: MRI is the gold standard to assess spinal canal anatomy. However, in this parturient in the acute care setting and with radiologically unassessed spinal canal problem, the bed-side assessment of lumbosacral sonoanatomy reassured anesthesiologist to a great extent. Measuring the depth of epidural space during pre-procedure scanning further enhanced the confidence of the anesthesiologist.This discourse promoted the use of epidural analgesia instead of choosing 4-6 Remifentanil PCA as an alternate analgesia-technique . References: 1. Anesthesiology 2011; 114: 1459-85 2. BMJ 2013; 346: f1720 3. Anaesthesia 1988; 43: 867-69 4. Anaesthesia 2013; 68: 283-87 5. Anaesthesia 2012; 67: 538-40 6. Anaesthesia 2013; 68: 231-35

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36359 - CEREBRAL OXIMETRY FOR CESAREAN DELIVERY IN A CASE OF MOYAMOYA DISEASE Author(s) Muhammad Ajmal, MBBS, DA Anesthesia Dept. of Anesthesia, Coombe Women and Infants University Hospital, Dublin, Ireland Role: Primary & Presenting Author Co-Author(s) Patrick Thornton, FCAI - Dept. of Anesthesia, Rotunda Hospital, Dublin, Ireland Introduction: Abnormalities in intracranial blood vessels predispose Moyamoya disease patients to 1 frequent ischemic and hemorrhagic strokes . Hemodynamic instability and the vascular response to anesthesia further increase this risk. We report cerebral oxygen saturation (rSO2) observations using non-invasive near infrared spectroscopic (NIRS) cerebral oximetry during a cesarean delivery (CD) under combined spinal epidural (CSE) anesthesia in a Moyamoya case. Case description: A 30-yr old, pre-obese [BMI 27.3] G1P0 woman diagnosed with Moyamoya disease at the age of 11 years was scheduled for an elective CD at 37 weeks gestation. The patient had suffered from ischemic and hemorrhagic strokes in the past. She had been epileptic since the diagnosis of Moyamoya and experienced frequent headaches during pregnancy due to her disease. The specific monitoring used during her CD involved invasive blood pressure recording and noninvasive NIRS cerebral oximetry. A low-dose intrathecal injection of 8 mg of heavy bupivacaine using CSE was sufficient to achieve an optimum block. The minor hemodynamic instability was treated with boluses of phenylephrine. An intravenous bolus of 5 i.u. oxytocin at a volume of 5 ml was injected over the span of one minute immediately following the delivery. Her rSO2 remained normal [60-75%] and was relatively higher after the delivery [See fig. below]. She remained comfortable and calm during the procedure and did not suffer from any complication due to her Moyamoya disease. Discussion: The clinical cerebral monitoring was supplemented by continuous rSO2 measurements using NIRS. This noninvasive cerebral oximetry measures the rSO2 in brain tissue in the area of 2 interest and is an indirect measure of the cerebral perfusion in that area . The normal range of rSO2 is 60-75%. NIRS cerebral oximetry is frequently used in procedures such as carotid endarterectomy and cardiopulmonary bypass surgeries but its use in obstetrical anesthesia is less common. NIRS has 3 been used in a Moyamoya parturient previously, however only for a portion of the cesarean delivery . We began measuring the patient’s rSO2 as soon as she arrived in the operating room. We applied cerebral oximeter over the frontal lobes of our patient because she had suffered from frontal lobe infarctions in the past. The increase in rSO2which was observed following delivery and administration of oxytocin was observed with no changes in the hemodynamics of the patient. We postulate that it may be as a result of vasodilatory effects of oxytocin on the cerebral circulation [See Fig. below]. Oxytocin leads to dilatation or constriction in a myriad of blood vessels. It has a vasopressinlike weak vasoconstrictive effect, and some reports suggest that it may reduce cerebral blood 4 5 flow (CBF), although other articles suggest an increase in CBF in experimental animals . The rSO2 6 monitoring in obstetric anesthesia is currently scarce . We propose that rSO2 should be monitored in Moyamoya patients undergoing anesthesia, particularly when oxytocin is administered. References: 1. N Engl J Med 2009; 360: 1226-1237 2. Curr Opin in Anaesthesiol 2010; 23: 576-581 3. Br J Anaesth 1996; 77: 550-552 4. Regul Pept.1996 62: 37-39 5. J Neurosurg 1992; 77: 424-431 6. Can J Anesth 1994; 41: 79-80

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36942 - ABDOMINAL COMPARTMENT SYNDROME IN A SEVEN YEAR OLD MALE TRAUMA VICTIM Author(s) Cameron Goldie, M.D. Anesthesia and Perioperative Medicine University of Manitoba Role: Presenting Author Caleb Zelenietz, M.D. Department of Anesthesia and Perioperative Medicine University of Manitoba Role: Primary Author Introduction: Abdominal compartment syndrome (ACS) is a life threatening entity in critically ill patients. Over the past decade there has been increasing awareness of ACS in trauma patients after 1,2 resuscitation . ACS in adults is defined as a sustained intra abdominal pressure (IAP) greater than 1 20 mm Hg that is associated with new organ dysfunction or failure . In children, ACS is defined as "a sustained IAP greater than 10 mm Hg with new or worsening organ dysfunction that can be attributed 1 to elevated IAP" . The normal range of IAP in critically ill children is 4-10 mm Hg. ACS has multiple 1 risk factors, including major trauma, shock and resuscitation . The World Society of the Abdominal Compartment Syndrome published definitions, diagnosis and treatment recommendations in 2013. They propose an algorithmic approach to the management of ACS that weakly recommends (grade 2D) decompressive laparotomy in adults suffering from ACS, along with treating the underlying etiology and optimizing the perfusion of intra-abdominal organs. Specific paediatric recommendations for the treatment of ACS include the use of decompressive laparotomy, paracentesis for fluid removal, negative pressure wound therapy to facilitate abdominal closure and attempted avoidance of a 1,3 positive cumulative fluid balance in at risk patients . The incidence of ACS after trauma and the frequency of leaving the abdomen open after trauma laparotomy may be declining due to the 4 decreased amount of crystalloid resuscitation . Discussion: Consent for this case report was obtained within the guidelines of our local ethics review board. We describe the case of a 30 kg seven year old male, with no past medical history. He injured his right leg by sliding into a functioning grain auger on a farm in a rural area. Nearly 6 hours later, he underwent emergent above-knee amputation (AKA) at our tertiary care paediatric hospital. In total, he received 100 mL/kg of intravenous fluids (IVF) prior to surgery, 30 mL/kg of red blood cells and 73 mL/kg of crystaliod. Hemodynamics worsened at the conclusion of the AKA in spite of repeated IVF boluses. Intra-abdominal hemorrhage was suspected based upon multiple clinical findings and the general surgery service was consulted intra-operatively. Laparotomy was performed in the context of unstable hemodynamics. No intra-abdominal pathology was identified. Hemodynamics improved once the laparotomy was performed. In total, he received 50 mL/kg of red blood cells, 50 mL/kg of crystalloid, and 17 mL/kg of volulyte IVF intra-operatively. Post-operative intravesicular pressures were 13 - 14 mmHg, but end organ function was preserved, so no further action was taken. Conclusions: Abdominal compartment syndrome is a life threatening condition often associated with critical illness. Prompt diagnosis and treatment is necessary to avoid its sequelae. References: 1) Intensive Care Med 2013 39:1190–1206 2) J Trauma (2003) 54:848 –861 3) Surg Clin N Am 2012 92:207–220 4) J Trauma Acute Care Surg 2014 epub ahead of print

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36987 - VALIDATING PATIENT SELF-REPORT TOOL IN PREOPERATIVE TRIAGE Author(s) Jeremy Russell Neufeld, BSc, MD Anesthesiology The Ottawa Hospital Role: Presenting Author Co-Author(s) Jennifer Wilson, MD - Anesthesiology, The Ottawa Hospital Sylvain Gagne, MD, FRCPC - Anesthesiology, The Ottawa Hospital Homer Yang, MD, FRCPC - Anesthesiology, The Ottawa Hospital Monica Taljaard, PhD - Clinical Epidemiology Program, Ottawa Hospital Research Institute Mary-Lou Crossan, BA, Medical Laboratory Technologist - Laboratory Medicine, The Ottawa Hospital Introduction: Preoperative screening tools relying on patient self-reported comorbidities are being 1, 2, 3, 4 . With multi-disciplinary input, we used in many institutions to help streamline pre-anesthetic care designed a questionnaire that, in another study, was shown to have a high level of agreement between patient self-reported comorbidities and those reported by anesthesiologists. Our study aims to validate the ability of this tool to appropriately triage patients into one of three pre-op assessment streams so that it can be used to better allocate resources in the Pre Anesthetic Unit (PAU). Methods: After obtaining local ethics board approval, 895 patients coming for elective non-cardiac surgery in June-December 2013 were selected as a convenience sample for our prospective observational study. Inclusion criteria were: 18 years of age or older, elective non-cardiac surgery not deemed to be high risk, and reading and writing competency in one of the official languages. Based on 57 possible comorbidities on the completed tool the patients were triaged into nursing telephone, nursing visit in person or anesthesiologist consult, which was deemed the highest level of assessment. This information was recorded on Form 1. Form 2 was placed in the patient chart for the anesthesiologist performing the anesthetic to provide their triage opinion and rationale prior to the induction of anesthesia. We calculated the rates of upgraded and downgraded visits, as well as the sensitivity and specificity of the questionnaire in correctly classifying patients requiring anesthesia consult, together with 95% confidence intervals (CI). Results: Of the 895 screened patients, 16 did not meet the inclusion criteria. 114 anesthesiologists participated, including 90 staff and 24 residents. Of the Form1-Form2 pairs, 385 (43.8%) were complete; 487 (55.4%) had a blank or missing Form 2; 6 (0.68%) were missing Form 1; and 1 surgery was cancelled. The results are recorded in Table 1. No adverse events or critical incidents were reported in any of the patients that anesthesiologists recommended be upgraded or downgraded. The sensitivity of the questionnaire in identifying patients who require anesthesia consult was 89.9% (95% CI 85.7%-94.1%) and the specificity was 79.0% (95% CI 73.2%-84.9%). Discussion: This study demonstrated that our tool can be used to help triage patients coming for elective non-cardiac surgery into the appropriate assessment stream. In particular, it can identify patients who require anesthesia consult with high probability (90%) and rule out those who do not (nearly 80%). In the majority of cases the anesthesiologist agreed with the tool triage classification. Common reasons for upgrade were difficult airway and uncontrolled respiratory disease. Downgrades were most frequently suggested for patients presenting with well controlled chronic disease (i.e. diabetes). This information will help guide future improvement of our tool and improve the efficiency of the PAU. References: 1. Can J Anaesth. 1998; 45:87–92 2. Journal of Arthroplasty. 2012; 27(10):1750-1756 3. Anaesthesia & Intensive Care. 2012; 40(2):297-304

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36990 - PERIOPERATIVE TRANSESOPHAGEAL ECHOCARDIOGRAPHY AS AN ADJUNCT TO ANGIOGRAPHY DURING THE DEPLOYMENT OF AN ENDOVASCULAR AORTIC GRAFT THROUGH AN EMBOLISED TRANSCATHETER TRANSAPICAL AORTIC VALVE IMPLANT Author(s) Marie-Jo Plamondon, MDCM FRCPC Anesthesiology University of Ottawa Role: Primary & Presenting Author Co-Author(s) Sudhir Nagpal, MD FRCSC FACS - Surgery, Division of Vascular Surgery, University of Ottawa Mireille Méthot, MD FRCSC - Surgery, Division of Vascular Surgery, University of Ottawa Jordan Hudson, MD FRCPC MPH - Anesthesiology, University of Ottawa An 83 year-old woman with significant comorbidities underwent an elective TAVI (transapical aortic valve implant) procedure due to severe aortic stenosis. The procedure was complicated by embolisation of the new prosthetic valve into the aorta. Initially, the valve was positioned too high above the annulus, and was deemed unstable with moderate paravalvular leaks. As the left ventricular apex was being closed, the valve embolised into the ascending aorta. There was then severe transvalvular and paravalvular regurgitation. At that point the cardiac team proceeded to the cardiac operating room for an emergent aortic valve replacement. The embolised valve migrated into the descending aorta, becoming lodged just below the diaphragm and 3cm above the celiac artery. The valvular leaflets remained closed and were facing the direction of the blood flow causing significant stenosis of the descending aorta, but paravalvular flow remained. Within 24 hours it was decided to bring the patient to the main operating room for urgent repair of the descending thoracic aorta. She was transported to the main OR (intubated, on Milrinone and Norepinephrine). The transesophageal echocardiography (TEE) examination revealed an embolised #23 Edwards Sapien XT valve with the 3 leaflets closed facing the aortic blood flow (Figure 1a). A small jet of blood was visible around the valve mainly on its posterior left side. TEE became a useful adjunct to angiography for accurate visualization of the guide wires within the valve. It was difficult to confirm with certainty the position of the wires solely based on angiography. After deployment of the first Palmaz stent, TEE demonstrated that the leaflets were still partially closed. A second Palmaz stent was deployed just 12mm below the prosthetic valve but encompassing its lower edge. At that point TEE was used to confirm that no residual closed leaflets could be seen. Once the deployment completed, flow within the new lumen was assessed by both angiography and TEE and was found to be adequate (Figure 1b). This case report illustrates how important TEE can be as an adjunct monitor in complex endovascular cases. As reported by Swaminathan & al., “transesophageal echocardiography has been found to be a valuable imaging tool for guiding placement of the endograft, detecting leaks around the endograft, (1) and supplementing information derived from angiography during endograft deployment” . TEE is (2) useful for guidewire positioning. Rocchi et al have developed an algorithm into which stent implantation procedures can be altered based on the transesophageal echocardiography results. With growing evidence of superiority of transesophageal echocardiography in comparison with (3) angiography, it has become common practice in our institution to use TEE in addition to angiography for monitoring in complex endovascular cases. References: 1. The importance of intraoperative transesophageal echocardiography in endovascular repair of thoracic aortic aneurysms. Swaminathan M, Lineberger CK, McCann RL, Mathew JP.Anesth Analg. 2003 Dec;97(6):1566-72. 2. Transesophageal echocardiography-guided algorithm for stent-graft implantation in aortic dissection. Rocchi G, Lofiego C, Biagini E, Piva T, Bracchetti G, Lovato L, Parlapiano M, Ferlito M, Rapezzi C, Branzi A, Fattori R. J Vasc Surg. 2004 Nov;40(5):880-5. 3. How to guide stent-graft implantation in type B aortic dissection? Comparison of angiography, transesophageal echocardiography, and intravascular ultrasound. Koschyk DH, Nienaber CA, Knap M, Hofmann T, Kodolitsch YV, Skriabina V, Ismail M, Franzen O, Rehders TC, Dieckmann C, Lund G, Reichenspurner H, Meinertz T. Circulation. 2005 Aug 30;112(9 Suppl):I260-4.

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36993 - POSTOPERATIVE OUTCOME OF PATIENTS WITH KNOWN OBSTRUCTIVE SLEEP APNEA Author(s) Eugene KH. Choo, MD Anesthesiology University of Ottawa Role: Primary & Presenting Author Co-Author(s) Claudia Gomez, MD - Anesthesiology, The Ottawa Hospital Monica Taljaard, PhD - Clinical Epidemiology Program, Ottawa Hospital Research Institute Gregory L. Bryson, FRCPC, MSc - Anesthesiology, The Ottawa Hospital Introduction: The ASA Clinical Practice guidelines on the perioperative management of patients with obstructive sleep apnea (OSA) suggest that patients with OSA are at high risk of perioperative apneic events and recommend they be monitored until they are no longer at risk (1). Guidance regarding duration of monitoring and use of constant positive airway pressure (CPAP) is vague. In June 2003, our institution introduced a protocol for the post-operative care of patients with diagnosed OSA. Patients diagnosed with OSA were monitored for a four-hour period following surgery. Those treated with CPAP were discharged to unmonitored wards, including those prescribed neuraxial opioids, if monitoring was uneventful. Patients non-compliant, or unable to use CPAP and those experiencing respiratory events during the monitored interval remained in a monitored setting overnight. The aim of this study was to document the outcomes of inpatients managed under this protocol. Methods: Ethics board approval was obtained for this retrospective cohort study. Database analysts identified all patients who underwent elective inpatient surgery between 2003.07.01 and 2012.03.31 who had previously undergone polysomnogram (PSG) testing at our institution. Records for airway surgery and procedures involving the surgical treatment for OSA were excluded. PSG reports were reviewed and OSA severity documented. In-hospital mortality and hospital length of stay were abstracted from administrative records. Inpatient records were reviewed manually to document patient, surgical and anesthetic characteristics. The use of high-dependency units (HDU), calls to the ICU outreach (RACE) team, post-operative complications, and compliance with CPAP was also recorded. Rate of in-hospital mortality and number of RACE calls between patients with PSG confirmed and absent OSA was estimated using the method of penalized likelihood (Firth's method). For planned and unplanned HDU admission, standard multivariable logistic regression analysis was used. Results: A total of 1586 subjects were included in the final analysis. 662 subjects (41.7%) did not have OSA based on PSG testing; leaving 924 (58.3%) with PSG confirmed OSA. Of the subjects with OSA, 281 subjects (17.7%) had mild OSA, 233 (14.7%) had moderate OSA, 335 (21.1%) had severe OSA and 75 (4.7%) had OSA of unknown severity. There were no significant differences in inhospital mortality (OR 0.78, 95% CI 0.06 to 9.6), unplanned HDU admission (OR 1.05, 95% CI 0.56 1.99), or RACE team calls (OR 1.19, 95% CI 0.57 to 2.6) among those with OSA. Length hospital stay (HR 1.06, 95% CI 0.98 to 1.14) was similar in those with and without OSA. Planned HDU admissions for overnight monitoring (OR 1.88, 95% CI 1.35 to 2.6) were significantly more frequent in those with OSA. Discussion: Patients with known sleep apnea undergoing inpatient surgery, managed under our institutional OSA protocol, did not experience an increased rate of mortality, morbidity, or unanticipated use of critical care resources. References: 1. Anesthesiology 2013 120: 00-00 (ahead of print)

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37002 - MALIGNANT HYPERTHERMIA (MH) TESTING IN PROBANDS WITHOUT MH-REACTION Author(s) Sheila Riazi, MSc, MD Anesthesia University Health Network Role: Primary & Presenting Author Co-Author(s) Carly Sterling - Anesthesia, University Health Network Henry Rosenberg, MD - Anesthesia, Saint Barnabas Medical Center, Livingstone, New Jersey, United States Natalia Kraeva, PhD - Anesthesia, University health network Introduction: Malignant hyperthermia (MH) is characterized by an adverse reaction to volatile anesthetic, and /or succinylcholine. Typically, following an adverse anesthetic reaction or positive 1 family history, patients will undergo caffeine-halothane contracture (CHCT) and/ or genetic testing. However, sometimes patients with no individual or family history of anesthetic reaction are referred for MH testing due to a variety of reasons. The objective of our study was to investigate reasons for referrals in non-anesthetic cases, and assess their phenotype. Methods: Following institutional research ethics board approval, all the CHCT-tested probands at our center were identified. Patients with anesthetic reactions were excluded. Reasons for referrals, baseline CK, genetics results, histopathology were analyzed and compared between patients with positive and negative CHCT results. Response to dantrolene among patients with positive CHCT was also assessed. Wilcoxon rank sums test, and fisher’s exact test were used for numerical, and categorical parameters, respectively. Results: Between 1992-2012, 152 referred probands from total of 525 were identified with no anesthetic reaction. Among these, 104 (68.4%) had positive CHCT. Reasons for referrals included unexplained high creatine kinase-CK (N=77, 50.6%), post viral chronic fatigue (N=63, 41.4%), postexercise rhabdomyolysis (N=12, 7.9%), and heat stroke (N=1, 0.6%). Fifty-nine patients with high CK (76.6%), and thirty -six patients with post-viral chronic fatigue (57.1%) had positive CHCT based on the standardized North American CHCT test protocol. The viral illness included influenza, EpsteinBarr, and cytomegalovirus. The fatigue was defined as muscle pain, weakness, and cramps, interfering with functional ability, lasted more than three months after the onset of viral illness. Mean CK levels (IU/L) were significantly higher in the group with positive CHCT (687.5 vs 321.3, p=0.013). Thirty-eight (36.5%) patients, all belonging to positive CHCT group, had abnormal histomorphology, including 9 patients with central core (CCD), and multi-minicores. Of all patients with positive CHCT, only 3 carried causative mutations in Ryanodine receptor-I (RYR-I). Two of these were referred for unexplained high CK, and one was referred for exercise-induced rhabdomyolysis. Forty patients with positive CHCT (38.4%) were given oral dantrolene, in which 30 (75.0%) responded with improvement of musculoskeletal symptoms, and reduction in CK, half of these patients were referred for post-viral fatigue symptoms Discussion: MH susceptibility as confirmed by the caffeine halothane contracture test may predispose patients to a variety of non anesthetic induced muscle abnormalities. The results support the contention that MH maybe more than an anesthetic disorder but should be interpreted in the context of the limitations of the sensitivity of the CHCT. References: 1- Glahn KP, Ellis FR, Halsall PJ, Müller CR, Snoeck MM, Urwyler A, Wappler F. European Malignant Hyperthermia Group. Recognizing and managing a malignant hyperthermia crisis: guidelines from the European Malignant Hyperthermia Group. Br J Anaesth. 2010 Oct;105(4):417-20.

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37035 - INDIVIDUALIZED BLOOD MANAGEMENT IN CARDIAC SURGERY USING A POINT-OFCARE BASED TRANSFUSION ALGORITHM Author(s) Debashis Roy Resident Department of Anesthesiology University of Toronto Role: Primary & Presenting Author Co-Author(s) Tarik Timoumi, MD - Anesthesiology, Université Paris Diderot-Paris Cielo Bingley, RN - ONTraC, University of Toronto Rafiq Kanji, MBChB - Medical Student, Keele University Stuart McCluskey, MD - Anesthesiology, University of Toronto Rita Selby, MD - Department of Laboratory Medicine & Pathobiology, University of Toronto Vivek Rao, MD - Department of Cardiac Surgery, University of Toronto Keyvan Karkouti, MD - Department of Anesthesiology, University of Toronto Introduction: Coagulopathy leading to excessive blood loss, blood product transfusion, and adverse 1,2 outcomes is a major complication of cardiac surgery with cardiopulmonary bypass. Current management of coagulopathic bleeding relies on conventional coagulation testing that have long 3 turnaround times and are not able to detect important coagulation defects such as fibrinolysis, 4 platelet dysfunction, or specific factor deficiencies. These shortcomings hamper management, forcing clinicians to delay therapy until the results become available or resort to empiric therapy based on their clinical judgment. These strategies are inefficient and potentially harmful because they can lead to underuse of blood products in some patients, leading to excessive blood loss and possibly re2,5 exploration, and to overuse of blood products in others. Individualized blood management using a transfusion algorithm that employs point-of-care coagulation tests may alleviate these problems. Methods: An integrated transfusion algorithm (Figure) that employed viscoelastic (ROTEM) and aggregometric (Platelet Works) point-of-care tests, as well as an objective measure of blood loss, was incorporated into routine practice at our hospital on January 2013. Following REB approval, we retrospectively compared the transfusion and clinical outcomes of patients operated from January to July 2013 (post-algorithm) to those operated on during 2012 (pre-algorithm), using multivariable Poisson regression (with robust confidence limits) to adjust for baseline differences. Results: Patients had similar characteristics pre- and post-algorithm. Incorporation of this algorithm into routine practice was associated with a significant (P < 0.0001) reduction in blood transfusion rates. Red blood cell transfusions decreased by 12% (from 52% pre-algorithm to 40% post-algorithm), platelet transfusions decreased by 15% (from 34% to 19%), and plasma transfusions decreased by 21% (from 34% to 13%). Post-algorithm, there was also significant improvement in clinical outcome such as re-exploration rate (P-0.001), major blood loss (P1500 ml of NS [OR 2.48, 95% CI 1.36-4.45, p