[Regional cerebral oxygen saturation as a marker of hemodynamic state following cardiac surgery]. / Saturación cerebral de oxígeno como marcador hemodinámico en la cirugía cardíaca.

INTRODUCTION: Regional cerebral oxygen saturation (rSO2) is a measure of the general state of perfusion and oxygenation. We aim to analyze the relationship between this and various hemodynamic and respiratory parameters. PATIENTS AND METHODS: Forty-three patients, operated on between October 2011 and July 2012, were included in this prospective observational descriptive study. The following parameters were measured: mean arterial pressure, both arterial and central venous oxygen saturation and partial pressures of oxygen and carbon dioxide, and lactate levels. From these parameters, the oxygenation index and the oxygen extraction ratio were calculated. These measurements were studied to evaluate whether rSO2 correlated significantly with the other parameters. RESULTS: The average age and weight of the patients were 27.3 months and 9.2 kg, respectively. The rSO2 correlated positively with both central venous oxygen saturation (r=0.73, P<.01) and mean arterial pressure (r=0.59, P<.01), and negatively with the oxygen extraction ratio (r=-0.7, P<.01). No correlation was found with the respiratory parameters. Concordance analysis established an acceptable Kappa index (> 0.4) between the rSO2 and central venous oxygen saturation, and between the rSO2 and oxygen extraction ratio. CONCLUSIONS: Regional cerebral oxygen saturation correlates well with hemodynamic parameters - mean arterial pressure, venous saturation, and the tissue oxygen extraction. However, it does not correlate with respiratory parameters.