RESUMEN
This paper contains a numerical study of the periodically forced van der Pol system. Our aim is to determine the extent to which chaotic behavior occurs in this system as well as the nature of the chaos. Unlike previous studies, which used continuous forcing, we work with instantaneous kicks, for which the geometry is simpler. Our study covers a range of parameters describing nonlinearity, kick sizes, and kick periods. We show that horseshoes are abundant whenever the limit cycle is kicked to a specific region of the phase space and offer a geometric explanation for the stretch-and-fold behavior which ensues.
RESUMEN
BACKGROUND: Ketamine has recently emerged as a promising therapeutic alternative for abortive migraine therapy, likely secondary to N-methyl-d-aspartate antagonism. Most reports examine adults and the intravenous route. Fewer utilize intranasal administration or pediatric populations. Given the limited evidence for intranasal ketamine in pediatric migraine populations, we retrospectively reviewed our experience to further characterize safety and efficacy of intranasal ketamine in this population. METHODS: A retrospective review in a free-standing, pediatric medical center was performed examining the utilization of intranasal ketamine at 0.1 to 0.2 mg/kg/dose up to five doses in pediatric migraineurs. Pain scores (scale = 0 to 10) were recorded at baseline and after each dose. Response was characterized as pain score reduction to 0 to -3 and/or reduction of at least 50%. RESULTS: Twenty-five encounters (25 of 34; 73.5%) were responders (mean pain score reduction of -7.2 from admission to treatment completion). Overall pain reduction from admission to discharge in the entire study population was 66.1%. Side effects were mild and transient. CONCLUSIONS: Our experience with intranasal ketamine has promising outcomes in both pain relief and side effect minimization. When other therapeutic options are unavailable, practitioners should consider intranasal ketamine.