Dexmedetomidine metabolic clearance is not affected by fat mass in obese patients.

BACKGROUND: Obesity has been associated with reduced dexmedetomidine clearance, suggesting impaired hepatic function or reduced hepatic blood flow. The aim of this study was to clarify the effect of obesity in dexmedetomidine metabolic clearance. METHODS: Forty patients, ASA I-III, 18-60 yr old, weighing 47-126 kg, scheduled for abdominal laparoscopic surgery, were enrolled. Anaesthetic agents (propofol, remifentanil, and dexmedetomidine) were dosed based on lean body weight measured by dual X-ray absorptiometry. Serial venous samples were drawn during and after dexmedetomidine infusion. A pharmacokinetic analysis was undertaken using non-linear mixed-effect models. In the modelling approach, the total body weight, lean body weight, and adjusted body weight were first tested as size descriptors for volumes and clearances. Hepatic blood flow, liver histopathology, liver enzymes, and gene expression of metabolic enzymes (UGT2B10 and UGT1A4) were tested as covariates of dexmedetomidine metabolic clearance. A decrease in NONMEM objective function value (ΔOFV) of 3.84 points, for an added parameter, was considered significant at the 0.05 level. RESULTS: A total of 637 dexmedetomidine serum samples were obtained. A two-compartmental model scaled to measured lean weight adequately described the dexmedetomidine pharmacokinetics. Liver blood flow was a covariate for dexmedetomidine clearance (ΔOFV=-5.878). Other factors, including fat mass, histopathological damage, and differential expression of enzymes, did not affect the dexmedetomidine clearance in the population studied (ΔOFV<3.84). CONCLUSIONS: We did not find a negative influence of obesity in dexmedetomidine clearance when doses were adjusted to lean body weight. Liver blood flow showed a significant effect on dexmedetomidine clearance. CLINICAL TRIAL REGISTRATION: NCT02557867.

Corrección de índice de dosis en tomografía computarizada por parámetro de diámetro efectivo según reporte 204 de la Asociación Americana de Físicos Médicos / Computed tomography dose index correction by effective diameter according to report 204 by the American Association of Physicists in Medicine

Abstract. In order to have a more accurate estimation of the dose delivered for computed tomography (CT) studies, and given that the current dose estimates do not include the size of the patient, a retrospective study was conducted on a sample of 388 patients from the radiology department of a general hospital, to make a better assessment of the dose delivered for CT scans of the chest, abdomen and pelvis in adult and paediatric patients. A comparison was made between the volume computed tomography dose index (CTDIvol) delivered by the scanner and CTDIvol value corrected by the incorporation of the effective patient diameter according to the report 204 of the American Association of Physicists in Medicine (AAPM). It was found that the values of CTDIvol vary in all cases when the patient size parameter is included, with this variation being greater as sizes go to extremes.

Resumen. Con el objetivo de tener una estimación de dosis más exacta entregada por los estudios de tomografía computarizada (TC) y dado que los estimadores de dosis actuales no incluyen el tamaño del paciente en la estimación, se realizó un estudio retrospectivo en una muestra de 388 pacientes de un servicio de radiología de un hospital general, para calcular las dosis entregadas en exámenes de TC de tórax, abdomen y pelvis en pacientes adultos y pediátricos. Se elaboró y realizó una comparación entre el índice de dosis de TC (CTDI VOL) entregado por el equipo y el CTDI VOL corregido mediante la incorporación del parámetro del diámetro efectivo del paciente según el reporte 204 de la Asociación Americana de Físicos Médicos (AAPM). Se pudo comprobar que los valores de CTDI VOL varían en la totalidad de los casos al ingresar el parámetro de tamaño del paciente y que esta variación es mayor a medida que los tamaños se van a los extremos.

Rocuronium pharmacokinetics and pharmacodynamics in the adductor pollicis and masseter muscles.

BACKGROUND: The aim of this study was to characterize the dose-effect relationship of rocuronium at the adductor pollicis and masseter muscles. METHODS: Ten, ASA I, adult patients, received a bolus dose of rocuronium 0.3 mg/kg during propofol based anesthesia. Train-of-four (TOF) was simultaneously monitored at the masseter and the adductor pollicis muscles until recovery. Rocuronium arterial serum concentrations were measured during 120 min. The first twitch of the TOF response was used to characterize the time-effect profile of both muscles using pharmacokinetic-pharmacodynamic analysis in NONMEM. A decrease in NONMEM objective function (∆OFV) of 3.84 points for an added parameter was considered significant at the 0.05 level. RESULTS: Onset time at the masseter (mean ± SD, 1.5 ± 0.9 min) was faster than at the adductor pollicis (2.7 ± 1.4 min, P < 0.05). Recovery, measured as the time to TOF ratio = 0.9 was similar between muscles 29.9 ± 6.7 (adductor pollicis) vs. 29.3 ± 8.1 (masseter). (P = 0.77). The estimated pharmacodynamic parameters [mean (95% CI)] of the adductor pollicis muscle and the masseter muscle were; plasma effect-site equilibration half-time (teq) 3.25 (2.34, 3.69) min vs. 2.86 (1.83, 3.29) min, (∆OFV 383.665); Ce50 of 1.24 (1.13, 1.56) mg/l vs. 1.19 (1.00, 1.21) mg/l, (∆OFV 184.284); Hill coefficient of 3.97 (3.82, 5.62) vs. 4.68 (3.83, 5.71), (∆OFV 78.906). CONCLUSIONS: We found that the masseter muscle has faster onset of blockade and similar recovery profile than adductor pollicis muscle. These findings were best, explained by a faster plasma effect-site equilibration of the masseter muscle to rocuronium.

Conceptualizaciones sobre la Medicina en el Dr Ernesto Guevara de la Serna / Conceptions on medicine by Dr Ernesto Guevara de la Serna

El Dr Ernesto Guevara de la Serna ejerció su profesión durante poco tiempo, pero dejó huellas indelebles en los pueblos y en la historia de la medicina en Nuestra América. Con este trabajo no se pretende valorar su faceta como facultativo, pero sí destacar sus estudios sobre la alergia y su pensamiento humanista, que estuvo presente desde sus primeros pasos en su profesión, en conceptos que evolucionaron en la medida en que viajaba y se enfrentaba a la realidad de su época y su medio, convirtiéndose en un abanderado de la medicina social. El Che viajó como “un soldado de América” por nuestro continente, estuvo allí donde nadie quería ir, vio el dolor , la pobreza, la desesperanza y comprendió el papel del médico, el que sólo con su presencia puede aliviar al hombre; entendió que no podía ser igual que sus colegas de la época; pudo tenerlo todo: honores, dinero, prefirió que sus únicos honorarios debían ser el agradecimiento del prójimo, la sonrisa de los pobres, la satisfacción del deber cumplido; se dio cuenta que la sociedad se lo impedía y decidió ser Médico Revolucionario, por eso contribuyó a realizarla, nos tocó a nosotros que la hiciera en Cuba y nos legó sus ideas. Sea, pues este trabajo un homenaje a él que lo dio todo por nosotros y no satisfecho con ello decidió dar la vida por “Su América”(AU)

La concepción téorica sobre la evaluación del aprendizaje / The theoretical conception on the professors´learning evaluation in the Surgery subject

Se realiza el estudio de la concepción teórica de los profesores de la asignatura de Cirugía como un primer paso en la investigación que sobre la evaluación del aprendizaje se realiza. Se efectuaron encuestas a profesores y estudiantes para realizar el diagnòstico sobre la concepción teórica que tiene el claustro. Se encuestaron 19 profesores y 27 estudiantes, de los cuales 16 eran de 4to. año y 11, de sexto. A estos últimos, se encuestaron para tener un criterio más acabado por haber cursado anteriormente la asignatura. Los profesores, en su mayoría, no consideran la evaluación como sinónimo de calificación y desean que la forma de hacerlo se cambie . No obstante, aunque el claustro expresó que el examen no era lo fundamental, para los estudiantes del sexto año examen y nota final es lo mismo y resulta estresante, lo que habla a favor de que la evaluación es sumativa y no formativa, y de corte tradicional. Por su parte, los profesores consideran que para una evaluación de calidad es necesario la evaluación cuantitativa y 48.1(por ciento) considera no estar preparado pedagógicamente para realizar un proceso de evaluación con calidad(AU)

Etiology of children's diarrhea in Montevideo, Uruguay: associated pathogens and unusual isolates.

We studied microorganisms associated with infant diarrhea in a group of 256 children admitted to a public pediatric hospital in Montevideo, Uruguay. Diagnostic procedures were updated to optimize detection of potential pathogens, which were found in 63.8% of cases, and to be able to define their characteristics down to molecular or antigenic type. Coinfection with two or more agents was detected in more than one-third of positive studies. Escherichia coli enteric virotypes, especially enteropathogenic E. coli (EPEC), were shown to be prevalent. Rotavirus, Cryptosporidium, Campylobacter (mainly Campylobacter jejuni), and Shigella flexneri were also often identified. Enterotoxigenic E. coli, Salmonella, and Giardia lamblia were sporadically recognized. Unusual findings included two enteroinvasive E. coli strains, one Shigella dysenteriae 2 isolate, and a non-O:1 Vibrio cholerae culture. EPEC bacteria and S. flexneri (but not Salmonella) showed unusually frequent antimicrobial resistance, especially towards beta-lactam antibiotics, which is the subject of ongoing work.

[Validation of the preparation of individual doses of 51Cr-EDTA in syringes]. / Validación de la preparación de dosis individuales de 51Cr-EDTA en jeringas.

The 51Cr-EDTA is one of the radiopharmaceuticals more used in the glomerular filtration rate determination. The necessity to prepare a daily reference dose every time that are prepared the patient's doses can go to a poor exploitation of the multidose vial. One way of improving its use consists on the preparation of individual doses in ready syringes to inject, for several days, employing only one of them as a standard. The aim of this study was to evaluate the storing of 51Cr-EDTA individual doses at room temperature and at 4 degrees C during 4 weeks, analyzing the radiochemical purity, the sterility and the radiopharmaceutical retention into the syringe. The results obtained showed that the radiochemical purity remains stable, always been greater than the value recommended for its use (> 95%). Likewise, there were not microorganism contamination nor 51Cr-EDTA appreciable retention into the syringes. We concluded that the preparation of individual doses of 51Cr-EDTA in syringes and their conservation at room temperature, or at 4 degrees C, during a period of 4 weeks, neither influence in the radiopharmaceutical quality nor increase its retention into the syringe.

[Stabilization of 99m Tc-HMPAO with methylene blue: its use in leukocyte labelling)]. / Estabilización del 99mTc-HMPAO con azul de metileno: su utilización en el marcaje de leucocitos.

A method to stabilize the 99mTc-HMPAO obtained from Ceretec(R) saline fractions using methylene blue is described. The mean radiochemical purity two hours after the stabilized 99mTc-HMPAO preparation was 92.5% (SD 1.8%), the pH ranged from 7.0 to 7.6 and the osmolality ranged from 305 to 309 mOsm/kg. These features made the stabilized 99mTc-HMPAO suitable for leukocyte labelling. In order to evaluate this method, we performed the labelling of two identical leukocyte samples withdrawn from 10 blood donors. The first sample was labeled using 99mTc-HMPAO non-stabilized and the second one was labelled using 99mTc-HMPAO stabilized 2 hours before with methylene blue. The mean labelling efficiencies we obtained were 70.9% (SD 6.9%) and 66.1% (SD 4.2%) respectively. With the conditions described using the 99mTc-HMPAO stabilized with methylene blue, we had no drawbacks from the stabilizing blue colour and we did not found changes in the cellular viability.

Determinacion de plomo en la sangre del cordon umbilical en recien nacidos normales. / Lead determinations in the blood of the umbilical cord of normal neonates

Se determinaron las concentraciones de plomo en la sangre del cordon umbilical de recien nacidos normales, asi como en sangre venosa de las madres, las muestras se obtuvieron simultaneamente durante el parto. Los valores obtenidos en 405 muestras dobles fueron, para las madres, de 0.97 +/- 0.28 micrograma mol/l (20.30 +/- 5.90 micrograma/dl), y para los recien nacidos de 0.67 +/- 0.25 micrograma mol/l (13.57 +/- 5.25 micrograma/dl). No se encontraron diferencias estadisticas significativas, si bien hubo cierta tendencia a concentraciones mayores en el area comercial entre las muestras de personas residentes en distintas zonas de la ciudad