Mark F. Levine

Clinical Characteristics of Sevoflurane in Children A Comparison with Halothane

Background For pediatric patients, sevoflurane may be an alternative to halothane, the anesthetic agent used most commonly for inhalational induction. The induction, maintenance, and emergence characteristics were studied in 120 unpremedicated children 1–12 yr of age randomly assigned to receive one of three anesthesia regimens: sevoflurane with oxygen (group S), sevoflurane with nitrous oxide and oxygen (group SN), or halothane with nitrous oxide and oxygen (group HN). Methods Anesthetic was administered (via a Mapleson D, F or Bain circuit) beginning with face mask application in incremental doses to deliver maximum inspired concentrations of 4.5% halothane or 7% sevoflurane. End‐tidal concentrations of anesthetic agents and vocal cord position were noted at the time of intubation. Elapsed time intervals from face mask application to loss of the eyelash reflex, intubation, surgical incision, and discontinuation of the anesthetic were measured. Heart rate, systolic, diastolic, and mean blood pressures, and end‐tidal anesthetic concentrations were measured at fixed intervals. Anesthetic MAC‐hour durations were calculated. The end‐tidal concentration of anesthetic was adjusted to 1 MAC (0.9% halothane, 2.5% sevoflurane) for at least the last 10 min of surgery. Intervals from discontinuation of anesthetic to hip flexion or bucking, extubation, administration of first postoperative analgesic, and attaining discharge criteria from recovery room were measured. Venous blood was sampled at anesthetic induction, at the end of anesthesia, and 1, 4, 6, 12, and 18–24 h after discontinuation of the anesthetic for determination of plasma inorganic fluoride content. Results Induction of anesthesia was satisfactory in groups SN and HN. Induction in group S was associated with a significantly greater incidence of excitement (35%) than in the other groups (5%), resulting in a longer time to intubation. The end‐tidal minimum alveolar concentration multiple of potent inhalational anesthetic at the time of intubation was significantly greater in patients receiving halothane than in patients receiving sevoflurane. Induction time, vocal cord position at intubation, time to incision, duration of anesthesia, and MAC‐hour duration were similar in the three groups. During emergence, the time to hip flexion was similar among the three groups, whereas the time to extubation, time to first analgesic, and time to attaining discharge criteria were significantly greater in group HN than in groups S and SN. Mean heart rate and systolic blood pressure decreased during induction in group HN but not in groups S and SN. The maximum serum fluoride concentration among all patients was 28 micro Meter. Conclusions Sevoflurane with nitrous oxide provides satisfactory anesthetic induction and intubating conditions; however, induction using sevoflurane without nitrous oxide is associated with a high incidence of patient excitement and prolonged time to intubation. There were greater decreases in heart rate and systolic blood pressure during induction with halothane than with sevoflurane; however, these differences may be dose‐related. The more rapid emergence with sevoflurane when compared with halothane is consistent with the low solubility of sevoflurane in blood and tissues. Children receiving sevoflurane for up to 9.6 MAC‐hours did not develop high serum fluoride concentrations.

Oral midazolam premedication in children: the minimum time interval for separation from parents

To determine the minimum time interval between oral midazolam (0.5 mg· kg−1) premedication and separation from parents that ensures a smooth separation, 30 children were assigned randomly to one of three groups (ten children per group). The groups differed only in the time interval between administration of midazolam and separation from their parents: 10, 20 or 30 min. Heart rate, systolic blood pressure, and sedation and anxiolysis scores were assessed before midazolam premedication (baseline), at the time of separation from parents, and during the application of a face mask at the induction of anaesthesia. We found that heart rate and systolic blood pressure changes were similar for all three groups throughout the study period. Sedation scores at the time of separation from parents and on application of the mask for all three groups were greater than baseline values. Sedation scores at separation did not differ among the three groups. Anxiolysis values did not differ from baseline values at any time for all three groups. We conclude that children may be separated from their parents as early as ten minutes after receiving oral midazolam, 0.5 mg · kg−1.RésuméAfin de déterminer le délai minimum entre une prémédication de midazolam par voie orale (0,5 mg· kg−1) et une séparation sans heurts d’avec leurs parents, 30 enfants ont été répartis aléatoirement en trois groupes (dix enfants par groupe). Seul le délai entre l’administration du midazolam et la séparation d’avec leurs parents différait d’un groupe à l’autre: 10, 20 ou 30 minutes. La fréquence cardiaque, la pression systolique, le niveau de sédation et d’anxiolyse ont été évalués avant la prémédication (valeur de base), au moment de la séparation et pendant l’application du masque facial à l’induction de l’anesthésie. Nous avons trouvé que les changements de fréquence cardiaque et de pression artérielle systolique ont été semblables dans les trois groupes au cours de notre étude. Le niveau de sédation à la séparation et l’application du masque a été plus élevé que la valeur de base et n’est pas différent entre les trois groupes. Le niveau d’anxiolyse n’a pas varié de la valeur de base à aucun moment dans les trois groupes. Nous concluons que les enfants peuvent être séparé de leurs parents aussi précocément que 10 minutes après avoir reçu 0,5 mg · kg−1 de midazolam par voie oral.

Plasma Inorganic Fluoride Concentrations after Sevoflurane Anesthesia in Children

BACKGROUND: Sevoflurane is degraded in vivo in adults yielding plasma concentrations of inorganic fluoride [F-] that, in some patients, approach or exceed the 50- micron theoretical threshold for nephrotoxicity. To determine whether the plasma concentration of inorganic fluoride [F-] after 1-5 MAC x h sevoflurane approaches a similar concentration in children, the following study in 120 children scheduled for elective surgery was undertaken. METHODS: Children were randomly assigned to one of three treatment groups before induction of anesthesia: group 1 received sevoflurane in air/oxygen 30% (n = 40), group 2 received sevoflurane in 70% N2O/30% O2 (n = 40), and group 3 received halothane in 70% N2O/30% O2 (n = 40). Mapleson D or F circuits with fresh gas flows between 3 and 61/min were used Whole blood was collected at induction and termination of anesthesia and at 1, 4, 6, 12, and 18 or 24 h postoperatively for determination of the [F-]. Plasma urea and creatinine concentrations were determined at induction of anesthesia and 18 or 24 h postoperatively. RESULTS: The mean (+/- SD) duration of sevoflurane anesthesia, 2.7 +/- 1.6 MAC x h (range 1.1-8.9 MAC x h), was similar to that of halothane, 2.5 +/- 1.1 MAC x h. The peak [F-] after sevoflurane was recorded at 1 h after termination of the anesthetic in all but three children (whose peak values were recorded between 4 and 6 h postanesthesia). The mean peak [F-] after sevoflurane was 15.8 +/- 4.6 microns. The [F-] decreased to <6.2 microns b 24 h postanesthesia. Both the peak [F-] (r2 = 0.50) and the area under the plasma concentration of inorganic fluoride-time curve (r2 = 0.57) increased in parallel with the MAC x h of sevoflurane. The peak [F-] after halothane, 2.0 +/- 1.2 microns, was significantly less than that after sevoflurane (P<0.00012) and did not correlate with the duration of halothane anesthesia (MAC x h; r2 = 0.007). Plasma urea concentrations decreased 24 h after surgery compared with preoperative values for both anesthetics (P<0.01), whereas plasma creatinine concentrations did not change significantly with either anesthetic. CONCLUSIONS: It was concluded that, during the 24 h after 2.7 +/- 1.6 MAC x h sevoflurane, the peak recorded [F-] is low (15.8 microns), F- is eliminated rapidly, and children are unlikely to be at risk of nephrotoxicity from high [F-].

Should all children with suspected or confirmed malignant hyperthermia susceptibility be admitted after surgery ? A 10-year review

Children otherwise suitable for same-day discharge may be admitted to the hospital solely because they are known or suspected to be malignant hyperthermia-susceptible (MHS). To determine whether their hospitalization is necessary, the medical charts of 303 children labeled MHS who had undergone surgery with anesthesia free of malignant hyperthermia-triggering agents on 431 occasions between 1981 and 1990 were reviewed. Eighteen of these patients (25 cases) who were subsequently identified as biopsynegative were excluded from the study. We recorded the reason for the MHS label and the perioperative management and outcome of the cases

Maintenance and recovery characteristics after sevoflurane or propofol during ambulatory surgery in children with epidural blockade

PurposeTo compare the maintenance and recovery characteristics after sevoflurane with those after propofol in children with epidural blockade.MethodsFifty unpremedicated, children ASA 1–11, 2 – 8 yr of age, scheduled for elective urological surgery as outpatients, were randomly allocated to receive either: I ) sevoflurane for induction and maintenance of anaesthesia or 2) propofol for induction (2–3 mg·kg−1iv) and for maintenance (5–10 mg·kg−1·hr−1iv). All children received N2O 70% in oxygen before induction and throughout the anaesthetic, rocuronium for neuromuscular blockade and a lumbar or caudal epidural block before incision. Heart rate (HR), systolic blood pressure (SBP), recovery times and all side effects during maintenance and recovery were recorded by a blinded observer. Adverse events during the first 24 hr were also recorded.ResultsMean HR increased 5–10% after induction in both groups reaching a maximum by five minutes. Heart rate returned to baseline by skin incision in the sevoflurane group and by 10 min after induction in the propofol group. During maintenance, HR decreased by 10–20% below baseline values by 20 min in the propofol group only, where it remained for the remainder of the anaesthetic. Similarly, SBP increased by 10% after induction of anaesthesia in both groups, but returned to baseline by 10 min. Light anaesthesia occurred in four (16%) children, all in the propofol group. Emergence and recovery indices were similar in the two groups.DiscussionSevoflurane and propofol exhibit similar maintenance and recovery profiles when combined with epidural analgesia in children undergoing ambulatory surgery.RésuméObjectifComparer les caractéristiques du maintien et de la récupération de l’anesthésie après l’administration de sévoflurane avec celles de l’anesthésie après le propofol chez des enfants qui ont subi un blocage péridural.MéthodeCinquante enfants ASA l–11, âgés de 2 à 8 ans, qui n’ont reçu aucune prémédication, devaient subir une chirurgie urologique élective ambulatoire et ont été répartis au hasard pour recevoir soit : I ) du sévoflurane pour l’induction et le maintien de l’anesthésie, ou 2) du propofol pour l’induction (2–3 mg·kg−1iv) et le maintien (5–10 mg·kg−1·hr−1iv). Tous les enfants ont reçu un mélange de N2O 70 % et d’oxygène avant l’induction et tout au long de l’anesthésie, du rocuronium pour le blocage neuromusculaire et une anesthésie péridurale lombaire ou caudale avant l’incision. La fréquence cardiaque (FC), la tension artérielle systolique (TAS), le moment de la récupération et tous les effets secondaires pendant le maintien et la récupération de l’anesthésie ont été enregistrés par un observateur impartial. On a aussi noté les événements indésirables pendant les 24 premières h.RésultatsLa FC moyenne a augmenté de 5–10 % après l’induction de l’anesthésie dans les deux groupes et a atteint sa valeur maximale en cinq minutes. Elle est revenue à sa valeur de base lors de l’incision cutanée dans le groupe sévoflurane et en dix minutes après l’induction dans le groupe propofol. Pendant le maintien de l’anesthésie, la FC a diminué de 10–20 % sous sa valeur de base en 20 min dans le groupe propofol seulement et elle est demeurée ainsi pour le reste de l’anesthésie. De même, la TAS a augmenté de 10 % après l’induction de l’anesthésie dans les deux groupes, mais est revenue à sa valeur de base en 10 minutes. Une anesthésie légère s’est produite chez quatre (16%) des enfants du groupe propofol. Les indices de réveil et de récupération ont été similaires dans les deux groupes.ConclusionLe sévoflurane et le propofol présentent des profils de maintien et de récupération similaires quand ils sont combinés à l’analgésie péridurale chez des enfants devant subir une chirurgie ambulatoire.

Competency-based medical education: Its time has arrived

In 2015, the Royal College of Physicians and Surgeons of Canada launched ‘‘Competence By Design’’ (CBD), a multi-year initiative designed to transform residency training in Canada using the principles of competencybased medical education (CBME). Departments of anesthesia in Canadian universities will be implementing a CBD curriculum with the cohort of new residents starting in July 2017. As described in this issue of the Journal, the Department of Anesthesiology at the University of Ottawa enrolled its first cohort of residents into an innovative competency-based program in July 2015. Many department chairs, clinicians, funding agencies, and other stakeholders may ask why we should change the way we’ve been training physicians for the past 100 years. They well recognize that we already turn out the most highly educated physicians in history and would be hard pressed to show that most are not competent. Are we currently educating residents in the most effective and efficient way possible to ensure they are prepared for certification, transition to practice, ongoing maintenance of certification, and development of advanced expertise? All stakeholders, including patients, hospital administrators, and governments, are increasingly demanding greater accountability and assurance that residents are trained in the most cost-effective manner, that specialists graduate with all the abilities required for independent practice, and that they continuously and transparently maintain and improve their performance. In our existing system, many trainees feel inadequately prepared for independent practice on graduation from residency. This is despite the fact that our training programs are perceived as very high standard and there is a high overall pass rate at the Royal College certification examinations. One of the guiding principles of CBME is to develop a program designed for graduates to achieve certain predefined outcomes —i.e., the competencies to practice safely and independently. The CBME methods and assessment tools are selected or developed to achieve these outcomes. Most jurisdictions have introduced some form of restricted duty hours, resulting in a significant reduction in time available for residency training, particularly for acquisition of clinical experience. It is therefore imperative that we rethink the way we currently train residents to ensure the training is more focused, effective, efficient, and cost-effective. Despite the reduction in total training time, the majority of residents still successfully complete residency and achieve specialty certification within the prescribed period. Does this signify that each graduate is ready for safe independent practice or that there are current limitations in measuring performance in a valid and reliable way? The inability of programs to identify underperforming residents, particularly early in training, may be compounded by the well-recognized concept of the ‘‘failure to fail’’. Dudeck et al. identified lack of documentation and ‘‘a lack of knowledge of what to specifically document’’ as two significant barriers to reporting a failing undergraduate student. Currently, residents are most commonly evaluated using poorly defined non-standardized metrics. In a CBME system, evaluators will need to use formative assessments based on M. F. Levine, MBBCh (&) Department of Anesthesia and Pain Medicine, The Hospital for Sick Children, The University of Toronto, Toronto, ON, Canada e-mail: mark.levine@utoronto.ca

Anaesthesia for insertion of ear tubes in children: comparison of propofol, thiopentone and halothane

To determine the quality of anaesthesia and speed of recovery after propofol anaesthesia for myringotomy in children, 100 children 2–12 years were randomized to one of four anaesthetic regimens for induction/maintenance: thiopentone (STP) (5 mg·kg−1)/halothane, propofol (3 mg·kg−1)/halothane, halothane/halothane or propofol (3 mg·kg−1)/propofol bolus (0.5 mg·kg−1 every 3 min (10 mg·kg−1·h−1)). Nitrous oxide (70%) in oxygen (30%) was used to facilitate insertion of an intravenous catheter and was continued throughout the anaesthetic. We found that the incidence of intraoperative movement in response to surgical stimulation was significantly greater in the prop/prop group 32%, compared with the three other groups (P<0.02). Although some recovery variables (time to response to questions, sit unaided, tolerate oral fluids, and discharge with fluids) were achieved more rapidly by the prop/prop group than the other three groups, the times to open eyes, obey commands and, most importantly, discharge from recovery without fluids did not differ between the prop/prop and the hal/hal groups. We conclude that there is little benefit in using propofol as an induction agent alone or in combination with a propofol maintenance anaesthetic for paediatric myringotomy and tube surgery.

Medical student impressions of anesthesiology and anesthesiologists.

To the Editor, Anesthesiology is not top-of-mind amongst medical students when it comes to career decision-making. Within the past ten years of the Canadian Residency Matching System, anesthesiology has consistently ranked outside the top ten most popular residency programs, as defined by the ratio of students applying to their firstchoice program to the quota of available positions. Recently, we undertook a survey to evaluate the attitudes and perceptions of University of Toronto (U of T) students towards anesthesiology and to identify factors influencing their selection or rejection of the specialty as a career. This insight could facilitate making improvements to the anesthesia curriculum within undergraduate medical education. After obtaining Research Ethics Board approval, we created the survey using the internet-based services offered by www.surveymonkey.com. We based the survey questions on a previous study and piloted the survey on medical students and anesthesia residents. Initial contact with all U of T medical students was made through the Office of the Dean of Undergraduate Medical Education. Students received an e-mail that included an information letter describing the study, a link to the web-based questionnaire, and particulars regarding the measures used to ensure confidentiality. Completion of the survey implied consent. Data were collected during the period from October 1, 2007 to December 31, 2007. One reminder was sent four weeks after the start of the study. Demographic data and information regarding year of training and anesthesiology experiences were collected together with respondents’ impressions and perceptions of anesthesia and anesthesiologists. We also solicited the ranking preferences, reasons for and against choosing anesthesia as a career, and the value of anesthesia rotations. Two hundred six (24.2%) students completed the survey with almost equal representation from each of the four undergraduate years. The female to male ratio was representative of the entire program (60:40). Anesthesia was ranked in the top three career choices by 28.2% of students, trailing behind internal medicine (58.7%), family medicine (58.3%), pediatrics (44.7%), surgery (41.7%), and obstetrics and gynecology (30.1%). Interest was lowest in Year 1 (16.9% of top three choices) and was stable in Years 2, 3, and 4 (34%, 30.6%, and 33.3%, respectively). Top reasons for selecting anesthesia included the scope of practice, practical hands-on experience, broad knowledge incorporation, lifestyle, and acute care nature of the specialty. Top reasons for rejecting the specialty included lack of knowledge or low exposure to anesthesia, boredom, and lack of continuity of care. Most students attributed roles, such as perioperative anesthesia and pain management during labour and delivery, to anesthesiologists, while less than one-third of the students ascribed roles, such as operating room management and expertise in resuscitation, acute/chronic pain management and fluid management, to anesthesiologists. This trend was more prevalent in Years 1 and 2. Most students (61.6%) responded that the anesthesia rotation should occur during the third year of the program, O. P. Adudu, MD F. A. Campbell, MD M. F. Levine, MBBCh (&) The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada e-mail: Mark.Levine@sickkids.ca

A national curriculum in anesthesia: rationale, development, implementation, and implications

In 2010, the Specialty Committee of the Royal College of Physicians and Surgeons of Canada (RCPSC) approved the use of the National Postgraduate Medical Education Curriculum in Anesthesia as a companion to the description of the Role of Medical Expert in the Objectives of Training Requirements (OTRs). The National Curriculum in Anesthesia represents the first of its kind in postgraduate medicine in Canada and will be a model for other national curricula moving forward. A collective consensus was reached amongst the Association of Canadian University Departments of Anesthesia (ACUDA) program directors and the RCPSC Specialty and Examination Boards that the time had come for a national curriculum. Ironically, the concept of developing a national curriculum in anesthesia was not new. The first efforts at developing a national curriculum in anesthesia began in 1971. A committee was established through the University Departments of Anesthesia (now known as ACUDA) to build a curriculum that would align curriculum objectives to specialist national exam criteria. In their commentary in 1974, Green et al. articulated the same rationale as is the impetus for the current project. Several sound reasons exist to create the standardized national curriculum. Over time, residents have found it more difficult to prepare for national examinations given the increasing overlap with other specialty disciplines in medicine and general surgery. Furthermore, the Examination Board did not have a well-defined curriculum around which to define the examination. With 17 different curricula driving one national exam, there was no assurance that anesthesia residents in all centres were being exposed to the specific elements of the medical expert competencies. With the growing demands of social accountability, there is increased pressure for programs to adapt to meet the challenges of aging populations, continuing change in health care systems, and complex work environments. While all postgraduate residency anesthesia programs were based on OTRs set out by the RCPSC and were all well developed prior to the National Curriculum in Anesthesia, there remained a gap in standardized curricular content to prepare residents for a standardized national exam in anesthesia. The introduction of competencies and the development of training models outside of the traditional apprenticeship approach to medical education were creating gaps for postgraduate medical educators in terms of matching objectives to assessment and learning strategies. The development of the recent National Curriculum in Anesthesia is a milestone in narrowing this gap.

Management of congenital tracheal stenosis - using spontaneous ventilation to facilitate cardiopulmonary bypass

We present an unusual case of an infant with life‐threatening tracheal stenosis scheduled for repair utilizing cardiopulmonary bypass. After repeated attempts at intubation endtidal CO2 was absent. The child was eventually managed with spontaneous breathing sevoflurane via a facemask. The possible causes of absent endtidal CO2 after intubation are discussed.