Homer Yang

Patients with aortic stenosis: Cardiac complications in non-cardiac surgery

PurposeTo reassess the risk of patients with aortic stenosis (AS) undergoing non-cardiac surgery.MethodsFollowing institutional approval, a retrospective chart audit of all patients with AS who underwent non-cardiac surgery in Hamilton between 1992 and 1994 was performed. For each AS case, a matching control was randomly selected. Data pertaining to pre-operative cardiac risk factors, intra-operative, and post-operative management were recorded. Complications were defined as the onset of congestive heart failure (CHF), myocardial infarction (M1), or dysrhythmias requiring cardioversion within seven post-operative days; unplanned or prolonged intensive care unit (ICU) stay due to cardiac cause; and cardiac death. Categorical data were compared using discordant data pairs and binomial distribution, with θ = 0.5. Parametric data were compared using students’ t test. All comparisons were two-tailed, with α < 0.05 considered significant.Results55 patients (32 male, 23 female, mean age 73 yr) with AS (mean aortic valve area 0.9 cm2) were studied. Cases and controls were identical for eight of nine pre-operative risk factors. Differences in perioperative management were found. Cardiac complications occurred in five cases and six control patients (P = 1.00).ConclusionsThe current study, involving 55 patients with AS undergoing non-cardiac surgery, showed no difference in the risk of cardiac complications compared with matched controls. However, the intensification of management in the AS patients may have attenuated the risk in this group. The sample size was adequate to detect a fourfold increase in risk.RésuméObjectifRéévaluer le risque, chez les patients présentant une sténose aortique (SA), de subir une chirurgie non cardiaque.MéthodeAprès avoir obtenu l’accord de l’institution, nous avons procédé à un audit rétrospectif des fiches de tous les patients souffrant de SA qui ont subi une chirurgie non cardiaque à Hamilton entre 1992 et 1994. Pour chacun des patients SA, il y a eu l’appariement au hasard d’un cas témoin. Des données relatives aux facteurs de risque cardiaque préopératoire, à la prise en charge intraopératoire et postopératoire ont été enregistrées. On a reconnu comme complications la survenue d’une insuffisance cardiaque congestive (ICC), l’infarctus du myocarde (IM) ou les troubles du rythme nécessitant une cardioversion dans les sept premiers jours postopératoires; un séjour non prévu ou prolongé à l’unité des soins intensifs (USI) en raison d’une cause cardiaque; l’arrêt cardiaque. Des données catégorielles ont été comparées en utilisant des paires de données discordantes et une distribution binomiale, avec θ = 0,5. Les données paramétriques ont été comparées selon le testt de Student. Toutes les comparaisons étaient bilatérales, avec α < 0,05 considéré comme significatif.Résultats55 patients (32 hommes, 23 femmes, dont l’âge moyen était de 73 ans) souffrant de SA (aire aortique moyenne de 0,9 cm2) ont été étudiés. Les patients et les témoins présentaient des fiches identiques pour huit des neuf facteurs de risque préopératoire. Des différences de mesures périopératoires ont été trouvées. Les complications cardiaques sont survenues chez cinq patients et six cas du groupe témoin (P = 1,00).ConclusionLa présente étude, réunissant 55 patients souffrant de SA et qui ont subi une chirurgie non cardiaque, n’a montré aucune différence de risque de complications cardiaques quand on les compare aux cas témoins qui leur sont appariés. Cependant, le renforcement des mesures thérapeutiques auprès des patients présentant une SA peut avoir atténué le risque dans ce groupe. Le nombre de sujets nécessaires à l’étude était suffisant pour détecter un accroissement de risque quatre fois plus grand.

Induction with sevoflurane-remifentanil is comparable to propofol-fentanyl-rocuronium in PONV after laparoscopic surgery

PurposeTo compare sevoflurane-remifentanil induction and propofol-fentanyl-rocuronium induction with regards to the frequency of moderate to severe postoperative nausea and vomiting (PONV) in the first 24 hr after laparoscopic day surgery.MethodsAfter informed consent, 156 ASA physical status class I to III patients undergoing laparoscopic cholecystectomy or tubal ligation were randomized to either induction with sevoflurane 8%, N2O 67% and iv remifentanil I to 1.5 βg · kg−1 or induction with iv fentanyl 2 to 3 μg · kg−1, propofol 2 mg · kg−1, and rocuronium 0.3 to 0.5 mg · kg−1. All patients received iv ketorolac 0.5 mg · kg−1 at induction and sevoflurane-N2O maintenance anesthesia with rocuronium as needed. PONV was treated with iv ondansetron, droperidol, or dimenhydrinate; postoperative pain was treated with opioid analgesics. Patients were followed for 24 hr with regards to PONV and pain. Intubating conditions, induction and emergence times, time to achieve fast-track discharge criteria, and drug costs were measured.ResultsNo differences were seen between the two groups in their frequencies of 24-hr moderate to severe PONV and postoperative pain, or in their intubating conditions, induction and emergence times, and time to achieve fast-track discharge criteria. Patients undergoing sevoflurane-remifentanil induction received more morphine (11 mg vs 8 mg; P < 0.001) in the postanesthetic care unit. Sevoflurane-remifentanil induction resulted in similar anesthetic and total drug costs for both procedures.ConclusionWe did not demonstrate any difference in PONV pain, or anesthetic/recovery times or costs between the sevoflurane and propofol groups. Sevoflurane-remifentanil induction is a feasible technique for anesthetic induction.RésuméObjectifComparer l’induction avec sévoflurane-rémifentanil ou propofol-fentanyl-rocuronium quant à la fréquence de nausées et vomissements postopératoires (NVPO) de modérés à sévères pendant les 24 premières heures après une opération en chirurgie d’un jour sous laparoscopie.MéthodeAprès avoir accordé leur consentement, 156 patients d’état physique ASA I à III devant subir une cholécystectomie laparoscopique ou une ligature des trompes ont été randomisés pour une induction avec du sévoflurane à 8%, N2O à 67 % et l à 1,5 μg · kg−1 de rémifentanil iv ou une induction iv avec 2 à 3 μg · kg−1 de fentanyl, 2 mg · kg−1 de propofol et 0,3 à 0,5 mg · kg−1 de rocuronium. Tous les patients ont reçu 0,5 mg · kg−1 de kétorolac iv à l’induction et un mélange de sévoflurane-N2O pour le maintien de l’anesthésie, avec rocuronium au besoin. Un traitement iv avec ondansétron, dropéridol ou dimenhydrinate a été donné pour les NVPO et la douleur postopératoire a été soulagée avec des analgésiques opioïdes. Les patients ont été suivis pendant 24 h pour les NVPO et la douleur. Ont été notés: les conditions d’intubation, les temps nécessaires à l’induction et au réveil, le temps d’atteindre les critères de congé de la chirurgie ambulatoire et le coût des médicaments.RésultatsAucune différence intergroupe n’a été enregistrée concernant la fréquence de NVPO de modérés à sévères et la douleur postopératoire pendant 24 h, ou les conditions d’intubation, les temps d’induction et de réveil, de même que le temps nécessaire à l’atteinte des critères de congé. Les patients soumis à une induction avec un mélange de sévoflurane-rémifentanil ont demandé plus de morphine (11 mg vs 8 mg; P < 0,001) en salle de réveil. L’induction avec sévoflurane-rémifentanil a conduit à un usage d’anesthésiques et à un coût total de médicaments similaires pour les deux types d’interventions chirurgicales.ConclusionNous n’avons trouvé aucune différence de NVPO, de douleur ou de temps liés à l’analgésie et à la récupération postopératoires entre les groupes sous sévoflurane ou propofol. Un mélange de sévoflurane-rémifentanil peut servir à l’induction de l’anesthésie.

Analysis of anesthesia physician resources: projected Ontario deficit in 2005

Purpose: To clarify the recent perception of shortfalls in anesthesia physician resources, two models were used to assess these resources in Ontario, Canada.Methods: Two models, demand-based and benchmarking, were used. In the demand-based model estimated future supply and attrition were obtained from information on Ontario Ministry of Health funded trainees. Data from the Canadian Residents Matching Service and the Association of Canadian University Departments of Anesthesia were also used. Current demand was identified from a telephone survey of Departments of Anesthesia in ten Ontario cities. The number of anesthesia practitioners in Ontario was estimated from the 1996 Canadian Anesthesiologists’ Society Physician Resource Database (CASPRD) in the demand-based model. In the benchmarking model, using Alberta as the closest published analogue to Ontario, the annual specialist growth rate in Ontario since 1986 was calculated in the literature as 2.8%/yr for 1986–1994. The number of anesthesiologists in Ontario from the 1986 CASPRD was used to calculate need based on that growth rate. Results are compared with population to anesthesiologist (P/A) ratios calculated from Statistics Canada population data and physician numbers from CASPRD.Results: A shortfall in the number of anesthesiologists has been identified. The P/A ratio worsened by 17.6% from 1986 to 1996. The demand-based model indicated that the shortfall is increased from a current deficit of 40 to 68 by 2005, using CASPRD. Benchmarking showed that the estimated shortfall in 1994 was 131.Conclusion: This conservative approach indicates that the shortfall in anesthesiologist physician resources will worsen by 2005.RésuméObjectif: Illustrer la récente observation de la pénurie de médecins en anesthésie en utilisant deux modèles pour évaluer les ressources en Ontario, Canada.Méthode: Deux modèles, l’un basé sur la demande et l’autre, un seuil de référence, ont été utilisés. Dans le modèle basé sur la demande, l’estimation des futurs effectifs et des départs volontaires a été obtenue à partir de renseignements de la liste des médecins en formation du Ministère de la Santé de l’Ontario. Les données du Canadian Residents Matching Service et de l’Association des départements d’anesthésie des universités canadiennes ont été aussi utilisées. La demande actuelle a été vérifiée par téléphone auprès des Départements d’anesthésie de dix villes de l’Ontario. Le nombre de praticiens en anesthésie en Ontario a été estimé à partir de la Canadian Anesthesiologists’ Society Physician Resource Database (CASPRD) pour le modèle basé sur la demande. Dans le modèle de référence, en utilisant l’Alberta comme analogue connu se rapprochant le plus de l’Ontario, l’augmentation annuelle du nombre de spécialistes en Ontario depuis 1986 a été calculée d’après la documentation comme étant de 2,8 % pour la période de 1986–1994. Le nombre d’anesthésiologistes en Ontario foumi par le CASPRD depuis 1986 a été utilisé pour calculer les besoins sur la base de ce taux d’augmentation. Les résultats ont été comparés avec les ratios de la population par rapport aux anesthésiologistes (P/A) calculés selon les données de Statistiques Canada sur la population et selon le nombre de médecins foumi par le CASPRD.Résultats: On a constaté une pénurie d’anesthésiologistes. Le ratio P/A s’est dégradé de 17,6 % de 1986 à 1996. Le modèle basé sur la demande a indiqué que la pénurie s’accroîtra d’un déficit actuel de 40 à un déficit de 68 en l’an 2005, selon le CASPRD. Le modèle de référence a montré que la pénurie estimée en 1994 a été de 131.Conclusion: Cette méthode conservatrice indique que la pénurie de médecins anesthésiologistes sera plus grave en 2005.

Intraoperative automated ST segment analysis: a reliable ‘Black Box’?

PurposeTo review the application of intraoperative computerized ST analysis and its potential impact on postoperative outcomes.SourceExisting anaesthesia and cardiology literature.Principal findingsComputerized ST analysis was introduced into the operating room using exercise electrocardiographic (ECG) systems. In spite of sophisticated algorithms, errors do occur. Downsloping or horizontal ST depression are the classical criteria for ischaemia. Although algorithms have been developed and evaluated in exercise stress testing, only limited evaluation has been carried out in the operating room. This may be a concern since circumstances in the operating room may frequently lead to false positives. Similarly, studies suggest that all myocardial ischaemia may not exhibit ST changes. The diagnostic accuracy of ST depression in exercise stress testing also cannot be assumed in the operating room. Finally, if ST analysis is applied widely, without considering the population or disease prevalence, misdiagnosis may occur.ConclusionGiven the number of anaesthetic tasks at-hand, on-line computerized ST analysis in the operating room can be a useful asset. The technology has its problems and should be applied with an understanding of its limitations and potential for errors. It should be applied in the operating room within the context of the population and disease prevalence.RésuméObjectifRevoir l’utilisation peropératoire de l’analyse du segment ST informatisée et son impact potentiel sur le pronostic postopératoire.SourceLa littérature anesthésique et cardiologique actuelle.Données principalesL’analyse informatisée du segment ST a fait son apparition en salle d’opération après les épreuves électrocardiographiques d’effort. Malgré la perfectionnement des algorithmes, des erreurs surviennent. Les sous-décalages en pente descendante et horizontaux représentent les critères classiques de l’ischémie. Bien que des algorithmes aient été développés et évalués en ce qui concerne l’épreuve d’effort, l’évaluation demeure incomplète pour la salle d’opération. Dans certaines conditions propres à la salle d’opération, l’incidence des faux positifs est alarmante. Des études suggèrent en outre que l’ischémie myocardique peut exister sans que des changements se manifestent au niveau du segment ST. Contrairement à l’épreuve d’effort, on ne peut présumer de la précision de la dépression du segment ST en salle d’opération. Finalement, des erreurs de diagnostic peuvent survenir si l’analyse du segment ST est généralisée sans qu ’on tienne compte du type de population et de la nature de la maladie.ConclusionEn anesthésie, considérant le nombre de tâches à accomplir, l’analyse du segment ST informatisée et «en ligne» en salle d’opération peut être utilisée avec avantage. Cette technologie pose des problèmes et doit être pratiquée en respectant ses limites et de son potentiel d’erreurs. Son utilisation en salle d’opération doit tenir compte du type de population et de la nature de la maladie.

Pulmonary thromboendarterectomy in a patient with giant cell arteritis

This report describes the case of a young woman presenting with signs and symptoms of chronic thromboembolic pulmonary hypertension who underwent pulmonary thromboendarterectomy (PTE) with concomitant coronary artery bypass. She died in the intensive care unit 1 day postoperatively. At autopsy the patient was found to have giant cell arteritis of the pulmonary arteries and ascending aorta. It is important to differentiate this disease from chronic thromboembolic pulmonary hypertension because its management and that of systemic vasculitis differs considerably.

Why should we teach medical students

Brull and John Bradley1 entitled “The role of anesthesiologists in Canadian undergraduate medical education”. The article examines the timely issue of the involvement by anesthesiologists in undergraduate medical education (UME). Their findings indicate that although thirteen of sixteen medical schools have mandatory clerkship rotations, few anesthesiologists are engaged in preclerkship training. It is suggested that the pedagogic advantages of including anesthesiologists in UME are overlooked by medical schools or that anesthesiologists are themselves reluctant to assume pre-clerkship teaching responsibilities. The latter might imply that anesthesiologists do not view teaching medical students as worthwhile. In this editorial, we would like to explore why anesthesiologists should teach medical students. The involvement of anesthesiologists at the preclerkship level may be an important step in ensuring medical students make an informed career choice to enter anesthesia. Under the current Canadian Residents Matching Service (CaRMS), medical students must declare their specialty choices by October of their clerkship year although final choices may be changed, with some difficulty, right until January. Since clerkship usually continues until April or May, a considerable proportion of the students must finalize their specialty choices before their rotation in anesthesia. If one reason for anesthesiologists to teach medical students is to increase recruitment, then it would be appropriate to examine the evidence for that notion. In our previous national survey in 1994, the quantity of anesthesia exposure in a medical school did not correlate with the number of students in that school entering anesthesia.2 In a survey of 76 US medical schools which offered anesthesiology preceptorships, the percent of graduates entering anesthesiology after taking the preceptorships, on a per school basis, ranged from 0 to 80%.3 It would seem, therefore, that the mere exposure of medical students to anesthesia is not a de facto reason for medical students to choose anesthesia as a career. However, in the same study, when the total number of students (n=1480) who took the anesthesiology preceptorship were compared with the students who did not (n=26,662), the proportions of students who entered anesthesia were 11.5% and 2.3% respectively;3 i.e., students who entered anesthesia were more likely to have taken an anesthesia preceptorship. The notion that exposure to anesthesia leads to increased recruitment would seem to be too complex an issue to gather clear evidence on a medical school by medical school basis. However, when viewed from a broader national perspective, with a larger sample size, the evidence exists to show that students who enter anesthesia are more likely to have taken an anesthesia preceptorship. Another reason for anesthesiologists to teach medical students may be to influence student attitudes towards anesthesia. In one American study, the presence of certified registered nurse anesthetists was found to be a negative factor in medical students’ career choice for anesthesia.4 In another study, a survey of ten medical schools was conducted. Of the four medical schools whose students performed best on the anesthesia knowledge quiz, two provided routine exposure to anesthesia while the other two instituted a one-on-one preceptor-student relationship.5 More students in the schools with the routine anesthesia exposure had a negative attitude towards anesthesia. Another study found that the attitudes towards anesthesia after the clerkship rotation was more positive.6 It would seem that student attitudes towards anesthesia after an anesthesia rotation are perhaps more dependent on local factors within a medical school. In part, this is an issue of quantity vs quality. From the perspective of individual medical schools, there are no studies correlating the quality of exposure to the recruitment rate. From the perspective of role models, a recent study in Australia found that for those students who intended to enter anesthesia (18%), 94% identified a positive role model compared to 65% for EDITORIAL 115

Postoperative Home Monitoring After Joint Replacement: Feasibility Study

Background We conducted a prospective observational study of patients undergoing elective primary hip or knee replacements to examine the feasibility of a postoperative home monitoring system as transitional care to support patients following their surgery in real time. Objective The primary outcome was the mean percentage of successful wireless transmissions from home of blood pressure levels, heart rate, oxygen saturation levels, and pain scores until postoperative day 4 with a feasibility target of ≥90%. Methods Patients with an expected length of stay ≤1 day, age 18-80 years, Revised Cardiac Risk Index ≤ class 2, and caretakers willing to assist at home were eligible. Patient satisfaction, as a secondary outcome, was also evaluated. Wireless monitoring equipment (remote patient monitoring, Telus Canada) was obtained and a multidisciplinary care team was formed. Results We conducted the study after obtaining Research Ethics Board approval; 54 patients completed the study: 21 males, 33 females. In total, we evaluated 9 hips, 4 hip resurfacing, 26 total knees, and 15 hemi-knees. The mean transmission rate was 96.4% (SD 5.9%; 95% CI 94.8-98.0). The median response to “I would recommend the Remote Monitoring System program to future patients” was 4.5 (interquartile range 4-5), with 1 being “strongly disagree” and 5 “strongly agree.” At 30 days postop, there was no mortality or readmission. Conclusions This is an evolving new paradigm for postoperative care and the first feasibility study on monitoring biometrics after primary hip or knee replacement. Postoperative home monitoring combines current technology with real-time support by a multidisciplinary transitional care team after discharge, facilitating postsurgical care with successful wireless transmission of vitals. The postoperative home monitoring implementation is, therefore, generalizable to other surgical discharges from hospitals. Trial Registration ClinicalTrials.gov NCT02143232; https://clinicaltrials.gov/ct2/show/NCT02143232 (Archived by WebCite at http://www.webcitation.org/71ugAhhIk)

Postoperative Home Monitoring After Joint Replacement: A Retrospective Outcome Study Comparing Cases With Matched Historical Controls (Preprint)

Background A retrospective cohort study was conducted in patients undergoing postoperative home monitoring (POHM) following elective primary hip or knee replacements. Objective The objectives of our study were to compare the cost per patient, readmissions rate, emergency room visits, and mortality within 30 days to the historical standard of care using descriptive analysis. Methods After Research Ethics Board approval, patients who were enrolled and had completed a POHM study were individually matched to historical controls by age, American Society of Anesthesiology class, and procedure at a ratio 1:2. Results A total of 54 patients in the study group and 107 in the control group were eligible for the analysis. Compared with the historical standard of care, the average cost per case was Can

Impact of routine tranexamic acid in cardiac surgery: Single centre review

5826.32 (SD 1418.89) in the POHM group and Can

Are β-blockers anesthestics?

9198.58 (SD 1513.59) for controls. After 30 days, there were 2 emergency room visits (3.7%) and 0 readmissions in the POHM group, whereas there were 8 emergency room visits (7.5%) and 2 readmissions (1.9%) in the control group. No mortalities occurred in either group. Conclusions The POHM study offers an early hospital discharge pathway for elective hip and knee procedures at a 38% reduction of the standard of care cost. The multidisciplinary transitional POHM team may provide a reliable forum to minimize readmissions, and emergency room visits within 30 days postoperatively. Trial Registration ClinicalTrials.gov NCT02143232; https://clinicaltrials.gov/ct2/show/NCT02143232 (Archived by WebCite at http://www.webcitation.org/73WQ9QR6P)