Interacción entre mivacurio y succinilcolina: vista desde otra perspectiva / Interaction between mivacurium and succinylcholine from a different point of view

RESUMEN

OBJETIVOS: La succinilcolina (SC) puede utilizarseinicialmente para continuar con mivacurio (MIV), y estea su vez como precurarizante. Esta interacción da lugara contradicciones y revisarlas es nuestro propósito.PACIENTES Y MÉTODOS: Los pacientes fueron intubadostras utilizar aleatoriamente MIV 100 µg Kg-1 (grupo 1),SC 1 mg.Kg-1 y al cabo de una recuperación del 50%,MIV 100 µg Kg-1 (grupo 2). En el grupo 3 el mismo régimenprecedido por una precurarización con MIV 10 µgKg-1. Electromiográficamente se determinaron máximoefecto (MAX), tiempo de comienzo (TC), índice de recuperaciónentre 10-25% y duración clínica (DUR) delMIV. Como MAX corregido (©MAX) consideramos lasustracción del bloqueo remanente al valor actual en losgrupos 2 y 3 y como velocidad de acción (VA) la relaciónentre MAX o ©MAX y TC. Se utilizaron análisis devarianza, pruebas de Student-Newman-Keuls y T paracomparaciones y p>0,05 como significancia.RESULTADOS: En los grupos 2 y 3 el MIV mostró unsignificativo incremento de MAX (97-98% vs 93), reducciónde TC (135-158 vs 279 segundos) y aumento de laVA, sin modificaciones en la DUR. Usando ©MAX seredujo a la mitad MAX (47-49%) y disminuyó VA (1,34-1,62 segundos/% vs 2,69-3,36). La precurarización noañadió cambios relevantes.CONCLUSIONES: Cuando se utiliza MIV antes de desaparecerlos efectos de la SC, habitualmente no se cuenta conel efecto remanente. Este ensayo corrigió el MAX y calculóla VA, reduciendo el bloqueo neto y la VA, representandoun antagonismo para la secuencia de ambos bloqueantes

ABSTRACT

OBJECTIVES: Succinylcholine (SCH) may first be usedand continue with mivacurium (MIV). MIV has beensuggested as a pretreatment. Conflicting results arisesfrom studies on SCH-MIV interaction. The followingtrial revisits this interaction.PATIENTS AND METHODS: The patients were intubatedafter randomized administration of 100 µg·Kg-1 of mivacurium(group 1) or 1 mg·Kg-1 of succinylcholine and,after 50% recovery, 100 µg·Kg-1 of mivacurium (group 2).A third group received the same regimen as group 2, precededby pretreatment with 10 µg·Kg-1 of mivacurium.Maximum effect (MAX), onset time, the 10%-25% recoveryindex, and duration of effect of mivacurium weredetermined by electromyography. In groups 2 and 3, thecorrected MAX was defined as the difference between theactual MAX effect and the residual block after administrationof succinylcholine, and speed of action was definedas the ratio between MAX or corrected MAX and onsettime. Data were subjected to analysis of variance and Student-Newman-Keuls and t tests for bivariate comparisons.A value of P less than 0.05 was considered significant.RESULTS: Groups 2 and 3 had significantly greaterMAX effects (97% and 98%, respectively) in comparisonwith group 1 (93%), shorter onset times (135 and 158seconds in groups 2 and 3 vs 279 seconds in group 1),and greater speed of action without changes in durationof effect. MAX was halved when corrected (to 47% and49% in groups 2 and 3, respectively), and speed of actionwas significantly reduced (from 1.34 and 1.62 seconds/%in groups 2 and 3 respectively, to 2.69 and 3.36seconds/%). Mivacurium pretreatment did not producerelevant clinical changes.CONCLUSIONS: When mivacurium is used before theeffects of succinylcholine disappear, a residual effect isnot usually taken into consideration. This study correctedMAX and calculated speed of action, demonstrating areduction in net block and speed of action, consistentwith an antagonistic action when the 2 blockers areadministered sequentially