Alejandro Delfino

Performance of the cerebral state index during increasing levels of propofol anesthesia : A comparison with the bispectral index

BACKGROUND:The cerebral state monitor is a new device to measure depth of anesthesia. In this study we compared the cerebral state monitor with the bispectral index (BIS) monitor during propofol anesthesia. METHODS:Fifteen healthy patients received a continuous infusion of propofol (300 mL/h). The cerebral state index (CSI) and the BIS values were recorded until burst suppression ratio ≥60%. Baseline variability, prediction probability, and agreement analysis between indices were evaluated. Clinical markers of loss of consciousness were also assessed. RESULTS:Mean awake BIS and CSI values were 95.6 and 91.6, respectively (P = 0.01). BIS and CSI prediction probability values (mean ± sd) were estimated to be 0.87 ± 0.08 and 0.86 ± 0.08, respectively (NS). The CSI tended to stabilize at values of 60–40 when estimated propofol concentrations at the effect site increased from 5 to 8 &mgr;g/mL. The BIS stabilized at values of 40–20 when the propofol concentrations at the effect site increased from 7 to 10 &mgr;g/mL. The mean BIS-CSI difference was −7.4 with 95% limits of agreement of 22.2 and −36.9. The BIS and CSI correlation with the burst suppression ratio was −0.60 and −0.97, respectively (P < 0.01). Predicted BIS and CSI values for loss of eyelash reflex in 50% and 95% of the patients were different (P < 0.05). CONCLUSION:The overall performance of both monitors during propofol induction was similar. However, the different dynamic profiles of these monitors indicate that BIS may be a more useful index for evaluating intermediate anesthetic levels, whereas CSI may be better for evaluating deeper anesthetic levels.

Evaluation of the effect of intravenous lidocaine on propofol requirements during total intravenous anaesthesia as measured by bispectral index

BACKGROUND I.V. lidocaine is increasingly used as an adjuvant during general anaesthesia. The aim of this study was to evaluate the effect of i.v. lidocaine in reducing propofol anaesthetic requirements during total i.v. anaesthesia (TIVA) maintenance and to evaluate its effect on early recovery from anaesthesia. METHODS Forty adult patients undergoing elective laparoscopic cholecystectomy under TIVA were randomly allocated into the lidocaine group (administered 1.5 mg kg(-1) i.v. lidocaine over 5 min followed by 2 mg kg(-1) h(-1)) and the control group (administered an equal volume of saline). Propofol was administered using a target-controlled infusion to maintain the bispectral index values between 40 and 60. After surgery, all infusions were discontinued and the time to extubation was recorded. Serial arterial blood samples were drawn to assess drug plasma levels. RESULTS The maintenance dose of propofol was significantly lower in the lidocaine group [6.00 (0.97) mg kg(-1) h(-1)] vs the control group [7.25 (1.13) mg kg(-1) h(-1); P=0.01]. Propofol plasma levels measured at the end of the infusion were 3.71 (0.89) μg ml(-1) in the lidocaine group and 3.67 (1.28) μg ml(-1) in the control group (P=0.91). The median time to extubation was longer (11.0 min; range: 10.0-21.0) in the lidocaine group vs the control group (8.3 min; range: 5.5-12.5; P=0.02). CONCLUSIONS I.V. lidocaine reduces propofol requirements during the maintenance phase of TIVA, particularly during surgical stimulation. This sparing effect is associated with an increased time to extubation. Owing to its effect on early recovery from anaesthesia, i.v. lidocaine should be taken into account when used as a component of i.v. anaesthesia.

The Dynamic Relationship Between End-Tidal Sevoflurane Concentrations, Bispectral Index, and Cerebral State Index in Children

BACKGROUND: To guide anesthetic administration with electroencephalogram monitors in children, an adequate characterization of the anesthetic effect measured by these monitors in this population is needed. We sought to quantify and compare the dynamic profile of sevoflurane’s effect measured with the cerebral state index (CSI) and the bispectral index (BIS) in children. METHODS: Fifteen healthy children, aged 3–15 yr, scheduled to undergo minor surgery were prospectively studied. During the simultaneous recording of CSI and BIS, the sevoflurane vaporizer was set at 6 vol % for 5 min and then decreased. End-tidal concentrations (CET) were measured. The CET–sevoflurane effect–site concentration equilibration and pharmacodynamics were modeled. Goodness of fit between models was compared. Data are typical value (coefficient of variation). RESULTS: Within the anesthetic depth range studied, the rate of change of sevoflurane’s effect expressed as the effect–site equilibration half-life (t1/2 ke0) was slower with the CSI [2.0 (14) min] than with BIS [1.2 (53) min] (P < 0.05). The estimated baseline effect of BIS and CSI before sevoflurane administration (E0) was 84 (39) for CSI and 87 (7) for BIS (NS). The sensitivity to sevoflurane hypnotic effect expressed in the C50 [steady-state CET eliciting half of the maximum response (Emax)] was 2.1 (68) % with CSI and 2.1 (16)% with BIS (NS). The Emax with CSI 45 (0) was higher than that with BIS 27 (39) (P < 0.05). The population prediction error was significantly better for BIS (−0.7 ± 26.9) than for CSI (−3.0 ± 178.6) (P < 0.05). CONCLUSIONS: In children, the t1/2 ke0 of sevoflurane and the pharmacodynamics of sevoflurane were quantified and the results were entirely dependent on the monitor used to measure its hypnotic effect. Within the anesthetic depth range studied, the rate of change of sevoflurane’s effect was slower with the CSI. To adequately guide sevoflurane administration with these monitors in children, these differences should be considered.

Propofol consumption and recovery times after bispectral index or cerebral state index guidance of anaesthesia

BACKGROUND We compared the propofol requirements and recovery times when either the bispectral index (BIS) monitor or the cerebral state monitor (CSM) is used to guide propofol anaesthesia. METHODS Forty patients undergoing laparoscopic cholecystectomy were studied. All patients were monitored with both monitors and were randomly allocated into two groups according to the monitor used to titrate propofol administration. Propofol was administered to maintain BIS or CSM within 40 and 60. Propofol consumption and clinical markers of recovery were assessed after surgery. RESULTS In the CSM group, the values of cerebral state index (CSI) and BIS were 47 (5) and 38 (6), respectively (P=0.00054). In the BIS group, the values of CSI and BIS were 47 (5) and 45 (2), respectively (P=0.15). In the BIS group, the total amount of propofol used was lower [109 (20) microg kg(-1) min(-1)] than in the CSM group [130 (27) microg kg(-1) min(-1)] (P=0.018). The time to eye opening was lower in the BIS [7.2 (3.5) min] than in the CSM group [10.7 (6.6)] (P=0.038). There were no differences in fentanyl consumption, or in other clinical markers of recovery. CONCLUSIONS Compared with BIS, propofol anaesthesia guided with CSI resulted in 20% higher propofol doses. This, however, does not lead to clinically relevant differences in recovery times.

Inserción de la simulación clínica en el currículum de Anestesiología en un hospital universitario. Evaluación de la aceptabilidad de los participantes

INTRODUCTION Clinical simulation is currently an integral part of the curriculum of the Anesthesiology residency programs in other countries. We aimed to describe and evaluate the insertion of simulation in an anesthesia residency training program. METHODS Activities feasible to be used for training in a simulated environment were classified into 2 modules: workshops for technical skills conducted with first year residents, and high fidelity simulation scenarios performed with second and third year residents. After each activity, and using an anonymous questionnaire, residents assessed their satisfaction and objectives accomplished. RESULTS A total of 18 activities: 6 skills workshops and 12 high fidelity scenarios were assessed. A total of 206 questionnaires were analyzed, corresponding to 41 residents. Almost all (96%) of respondents agreed or strongly agreed that workshops met the objectives and should be mandatory in the anesthesia curriculum; however, 11% agreed that the activity caused anxiety and/or nervousness. The high fidelity scenarios were considered realistic and consistent with the objectives by 97% of residents, and 42% felt that workshops caused anxiety and/or nervousness. CONCLUSIONS The inclusion of simulation has been well accepted by the residents. The activities have been described as realistic, and limited to the objectives, essential points in adult education, as according to Kolbs learning model this is associated with profound, useful and long lasting knowledge.

Validation and piloting of direct observation of practical skills tool to assess intubation in the Chilean context

Background: The use of Workplace-Based Assessment (WBA) has increased in recent years. Aims: To create a modified version of Direct Observation of Procedural Skills (DOPS) adapted to the Chilean context and establish its psychometric properties. Methods: The content validity of DOPS was established through interviews and consensus survey. To be included in the new version, the respective domain should have been considered by over 80% of interviewers and it should have a Content Validity Index (CVI and kappa statistic over 0.78 and 0.6, respectively. For four months, the new DOPS was used to assess the intubation skills of the anesthesia trainees. Generalizability theory was used to establish reliability and internal consistency. Results: The interview suggested a DOPS with twelve domains. All were included in the final version as the CVI and kappa values were above 0.9 and 0.8, respectively. 585 procedures were assessed. The G coefficient was 0.90. The intubation needs to be assessed with DOPS at least six times to obtain a G coefficient of 0.80. Conclusions: The modified DOPS was a valid, reliable and practical tool for assessing the intubation procedure. Effort needs to be made to improve the staffs feedback skills.

Evaluación de docentes clínicos de Postgrado: desarrollo y propiedades psicométricas del instrumento MEDUC-PG14

Experts in medical education, teachers and residents of a medical school participated in interviews and focus groups. With this information, 26 categories (79 items) were proposed and reduced to 14 items (Likert scale 1-5) by an expert’s Delphi panel, generating the MEDUC-PG14 survey, which was answered by 123 residents from different programs of medical specialties. Construct validity was carried out. Factor analysis showed three domains: Teaching and evaluation, respectful behavior towards patients and health care team, and providing feedback. The global score was 4.46 ± 0.94 (89% of the maximum). One teachers’ strength, as evaluated by their residents was “respectful behavior” with 4.85 ± 0.42 (97% of the maximum). “Providing feedback” obtained 4.09 ± 1.0 points (81.8% of the maximum). MEDUC-PG14 survey had a Cronbach’s alpha coefficient of 0.947.

Effect of acute arterial hypertension on morphine requirements and postsurgical pain

STUDY OBJECTIVE The study objective was to establish the impact of acute hypertension on morphines requirements after laparoscopic cholecystectomy. DESIGN The design was a randomized, simple blinded study. SETTING The settings were operating room, postoperative recovery area, and first postoperative day. PATIENTS There were 50 patients, American Society of Anesthesiologists I-II, aged 18-50 years, undergoing elective laparoscopic cholecystectomy with general anesthesia. INTERVENTIONS Anesthetic management was standardized using propofol for induction, isoflurane for bispectral index (BIS) ranging between 40 and 60, and remifentanil maintained at a constant rate of 0.4 μg kg per minute throughout surgery in all patients. Once intubated, patients were randomly allocated to 1 of 2 groups: hypertensive group: systolic arterial blood pressure was maintained with phenylephrine infusion 20%-30% over baseline; control group: systolic arterial blood pressure was maintained 20%-30% below baseline. All surgical incisions were infiltrated with bupivacaine 0.5%, and every patient received ketorolac 60 mg intravenous. Patient-controlled analgesia with morphine intravenous was used for postoperative analgesia. MEASUREMENTS Pain visual analogue scale scores, arterial blood pressure, and hyperalgesia were assessed at recovery room every 15 minutes during the first 2 postoperative hours and then at 6, 12, and 24 postoperative hours. Cumulative morphine consumption was registered at 2 and 24 postoperative hours. MAIN RESULTS The cumulative morphine consumption in the control group was around 18 mg compared with 6 mg in the hypertensive group (P = .019). During the first 75 minutes after surgery, the control group had higher visual analogue scale score pain compared with hypertensive group (P = .005). CONCLUSIONS The intraoperative acute generation of mild hypertension with phenylephrine reduced postoperative morphine consumption and pain scores after laparoscopic cholecystectomy.

Incorporación de paciente virtual en portafolio de estudiantes de medicina de pregrado

Background: In 2007, a Clinical-Case-Portfolio (CCP) was introduced as a new assessment instrument for fourth grade undergraduate medical students. Since then, several changes have been implemented such as reduction on the number of clinical cases, peer review and the introduction of virtual patient to the portfolio. Aim: To describe the virtual patient model incorporated to the CCP and assess the perception of this change and its effects on the performance of undergraduate students. Material and methods: Virtual patients were implemented based on prototype clinical cases with specific syndromes. Students’ perceptions about CCP before and after the introduction of virtual patients were evaluated using a validated questionnaire that was answered voluntarily and anonymously. Results: Overall perception of CCP significantly improved after the incorporation of virtual patients (97.1 ± 24.9 and 111.3 ± 25.7 points; 57.8 and 66.2% respectively). The same improvements were observed for the domains “Student Learning”, “Organization and Evaluation”, “Teaching Methodology” and “Integration”. In both years, students obtained high grades in CCP evaluations. However CCP grades were not significantly correlated with integrated final grades. Conclusions: The incorporation of virtual patients improved undergraduate students’ perception of CCP.

Inserción de b-learning como metodología de enseñanza teórica en el programa de especialidad de anestesiología

Introduccion Se ha demostrado que los metodos de ensenanza tradicionales, centrados en el profesor, no se ajustan a los requerimientos de los alumnos actuales. Nuestro objetivo es describir la transformacion del curriculum teorico del Programa de residencia de Anestesiologia, de clases presenciales a la nueva metodologia de estudio guiado a traves de b-learning (blended learning). Metodos Se realizo un analisis del curriculum existente, agrupando los temas en 11 modulos tematicos de 4 semanas cada uno. Se reviso y actualizo la literatura segun objetivos especificos de cada modulo y se identificaron las destrezas clinicas que debian ir asociadas a cada contenido. Posteriormente, se seleccionaron clases teoricas para ser grabadas y subidas a la plataforma, de una duracion maxima de 20 minutos. Se seleccionaron lecturas obligatorias y complementarias, y se desarrollaron actividades de aprendizaje como tareas, controles en linea, foros, Wikis y Webquests. Al final de cada modulo, se planificaron sesiones presenciales con actividades de simulacion, trabajos en grupo pequeno, clases magistrales de expertos, una evaluacion escrita y encuestas de satisfaccion de los alumnos. Los tutores recibieron capacitacion para el manejo de la plataforma Sakai a traves de UCvirtual. Resultados La primera version de esta nueva metodologia se implemento con los 18 residentes de primer ano del Programa de Especialidad de Anestesiologia desde mayo 2013 hasta abril del 2014. Diez y seis alumnos –realizaron los 11 modulos en forma exitosa y dos abandonaron el Programa de Especialidad. Se realizaron encuestas de satisfaccion a los alumnos al final de cada modulo, en las cuales se evaluo, con una escala de Likert de 1 a 4, la relevancia de los temas tratados para la practica anestesiologia actual (promedio 3.75), el valor de las actividades de aprendizaje (promedio 3.38), la ayuda brindada por los tutores (promedio 3.47) y la interaccion con la plataforma (promedio 4.43), entre otras variables. En cuanto a las evaluaciones negativas, destaco la mencion casi unanime de sobrecarga de trabajo (promedio 2.72), muy superior a las 10 horas semanales declaradas en el programa para la realizacion de todas las actividades. Esto motivo una reevaluacion de cada uno de los modulos, ajustando especialmente la cantidad de lecturas y de actividades de aprendizaje. De esta manera, la version 2014, actualmente en curso, ha tenido evaluaciones igualmente positivas en cuanto a calidad de los contenidos y docentes, y un nivel de satisfaccion de los alumnos superior en cuanto a la carga de trabajo. Conclusiones La introduccion de la modalidad de b-learning ha tenido una buena aceptacion por parte de nuestros alumnos. Les ha permitido organizar su estudio y trabajo en linea ajustando a sus necesidades profesionales, familiares y personales. Las sesiones presenciales son altamente valoradas por su aplicacion practica e inmediata a su actividad clinica diaria. Todos estos elementos son claves para un modelo exitoso de aprendizaje del adulto. Nuestra tarea pendiente es evaluar si esta modalidad permite a nuestros alumnos un aprendizaje mejor y mas profundo que los metodos tradicionales.