Changes in sympathetic outflow, and the associated cardiovascular effects, are well known to occur during refractory intracranial hypertension, uncal herniation and brainstem death. However, sympathetically mediated changes in renal perfusion and the cortical microcirculation, although hypothesised to occur, are not well documented. Using contrast enhanced ultrasound, the presented case demonstrates a dramatic improvement in, previously abnormal, renal blood flow following uncal herniation. These findings potentially illustrate the effect of sympathetic tone on organ perfusion and the microcirculation in critical illness. Future study in this area may have important implications on vasopressor and organ transplantation practices.
McDonald et al. (Fri,) studied this question.