Abstract
Background: Prompt reperfusion is essential to rescue ischemic tissue, but in itself represents a key pathomechanism contributing to poor outcome after cardiac arrest. Experimental data suggest levosimendan as a therapeutic drug to limit ischemia-reperfusion injury by improving cerebral microcirculation and thereby reducing neuronal injury. However, recent studies question its effect on cardiac output and cerebral microcirculation in normally pumping hearts. The present study was designed to investigate the influence of levosimendan on hemodynamic parameters, cerebral perfusion, and cerebral oxygenation after cardiac arrest and resuscitation.Methods: Ventricular fibrillation was induced in anesthetized juvenile male pigs for 7 min, followed by cardiopulmonary resuscitation. After return of spontaneous circulation (ROSC) animals were randomly assigned to levosimendan (12µg/kg, followed by 0.3µg/kg/min) or vehicle (normal saline) treatment for 6 hours. Cerebral oxygen saturation and brain tissue oxygen levels were determined with near-infrared spectroscopy (NIRS) and fluorescence quenching tissue PbtO 2 probes. Cerebral and kidney perfusion were quantified by fluorescent-labeled microspheres and laser-doppler flowmetry. Results: Compared to vehicle, levosimendan treated animals showed significantly higher brain tissue oxygen levels after ROSC. This effect was not accompanied by changes in cardiac output, cardiac preload and afterload, arterial blood pressure, nor cerebral microcirculation, indicating a local levosimendan-mediated effect in the brain.Conclusions: Cerebral oxygenation is key to minimizing neurological damage during and after cardiac arrest. Therefore, current concepts aim at improving impaired cardiac output or cerebral perfusion pressure. In the present study we provide evidence that NIRS fails to reliably detect low brain tissue oxygen levels and that levosimendan improves brain oxygen content. Levosimendan may therefore present a promising therapeutic approach to rescue brain tissue at risk in patients after cardiac arrest or other causes of cerebral ischemia or malperfusion such as stroke or traumatic brain injury.
Using robotic technology to quantify neurological deficits among survivors of critical illness: do they relate to brain tissue oxygen levels? a pilot study
