Utilización de un modelo animal para entrenamiento, en oxigenación por membrana extracorporea (ECMO) / The use of an animal model for extracorporeal membrane oxygenation (ECMO) training

ECMO es un procedimiento de rescate de recién nacidos (RN) con fallo respiratorio hipoxémico severo que no responde al tratamiento convencional. Previo a la instrumentación de esta técnica en pacientes, se realizó el entrenamiento experimental en animales. Existe escasa bibliografía sobre la utilización de porcinos como modelo animal en ECMO. Se reportan, en cambio, la implementación de otros animales, tales como el cordero. Objetivo: determinar la utilidad y el comportamiento modelo animal eligido, su respuesta al procedimiento de ECMO, describir la técnica utilizada y sus resultados. Método: se utilizaron dos porcinos de la raza Landrace, de 30 y 45 días de vida. Se canularon la vena yugular interna y la arteria carótida interna derechas; se realizó el ensamblado y purgado del circuito. El bypass se inició con un flujo de bomba de 20 mL/K/min, aumentandose hasta 100-120 mL/K/min; logrado un flujo de 80 mL/K/min se disminuyeron los parámetros de Asistencia Respiratoria Mecánica (ARM) a nivel de reposo. Durante el curso de ECMO se practicaron diferentes acciones relacionadas con el manejo del sistema de perfusión y evaluación del comportamiento clínico del modelo. Finalmente se suspendió electivamente el procedimiento; luego el animal fue dacanulado y recuperado. Resultados: tiempo promedio de ECMO: 24.5 horas. Signos vitales del animal estables. No hubo complicaciones relacionadas con el circito, ni presencia de sangrado sistémico. Se lograron tasas deseadas de hemofiltración. Ambos animales sobrevivieron. Como complicación se registró hematuria en un caso. Conclusión: El modelo animal elegido, para el entrenamiento en el manejo de ECMO, fue satisfactorio.

Impact of Babesia bovis and Babesia bigemina on the production of beef cattle in Uruguay

Uruguay is situated in a marginal area for the development of Boophilus microplus (30- 35- South Lat.) with important areas of enzootic instability for Babesia bovis and B. bigemina. The livestock products represent 70% of our exports, for wich reason it is fundamental to evaluate the losses in the production that these haemoparasites cause as basic information to take future decisions. In the period 1988-1990, several works were carried out by our laboratory to know the incidence of babesiosis in the reduction of liveweight gains. The results are shown and discussed in the work. Experiment I: the weight increase of the control group (x = 0,248kg/day), was 23% higher than that of the infected group with Babesia spp (from Uruguay), but significant statistical differences were not found (P < 0,05). These animals were kept in boxes and the food was controlled for 76 days. Experiment II: the incidence of Babesis spp (same strain ) was studied for 140 on Hereford heifers (n = 14) on natural pastures. The control group obtained x = 25,29kg of liveweight gain and it was 45% higher than that of the infected group, significant statistical difference were found (P < 0,05). Experiments with attenuated strains III: four studies were carried out inoculating B. bovis and B. bigemina in bovines about one year old, in different growth systems, searching for the limit of application. Significant statistical differences between those groups were found during the experiment (about 180 days) (P < 0,05). Experiment combining and pathogenic strains IV: the liveweight gain, in immune and challanged group (n = 14) was the same than that of the unchallenged group and did not show significant statistical differences (P < 0,05). However the control challenged group had less weight gain and statistical differences were found (P < 0,05). Although this is a preliminary information, it shows that: (a) the incidence of babesiosis on the reduction of weight gains is important; (b) the decrease in weight gain was not observed when attenuated strains were used; when the challenge was done in immunized animals, losses in liveweight gain were not observed. These results are discussed in order to plan future studies in different real systems of production