Cerebral Oxygenation During Hypoxia and Resuscitation by Using Near-infrared Spectroscopy in Newborn Piglets

Abstract

Hypoxic events and cardiac arrest may cause brain damage in critical infants. This study investigated cerebral tissue oxygenation and oxygen extraction in a piglet model of hypoxic events, cardiac arrest and effects of resuscitation. For the hypoxia experiment, anesthetized newborn piglets were randomized to a hypoxia group (n = 8) with decreasing ventilatory rate to 0, and a control group (n = 8) with no hypoxic conditions. Regional cerebral tissue oxygen saturation (rScO2, detected by near-infrared spectroscopy) and oxygen saturation were recorded every 5 minutes for 100 minutes. Fractional cerebral tissue oxygen extraction (FTOE) was calculated as (arterial oxygen saturation [SaO2] - rScO2)/SaO2. For the resuscitation experiment, animals were grouped as hypoxia-no CPR (n = 4), control-no CPR (n = 4), and control-CPR (n = 4) after cardiac arrest. Standard cardiopulmonary resuscitation (CPR) was performed on the control-CPR group and observed for 30 minutes. Immediate and significant changes in rScO2, and gradual changes in FTOE were observed during the hypoxia experiment. In the resuscitation experiment, no significant differences in rScO2 were found between groups. However, the highest FTOE was observed in the control-CPR group. Noninvasive monitoring of rScO2 and evaluating FTOE changes during hypoxia and resuscitation may help clinicians evaluate brain tissue oxygenation and viability.