Abstract 17438: Post Cardiac Arrest Oxygenation as a Determinant of Cardiac Function Recovery
Background: Reintroduction of oxygen following cardiac arrest generates reactive oxygen species (ROS) leading to myocardial stunning and reperfusion injury. We hypothesize that the level of oxygenation following restoration of spontaneous circulation (ROSC) is an important determinant of short-term cardiac recovery.
Methods: Anaesthetized, ventilated male Sprague-Dawley rats (400–450 g) were instrumented for cardiopulmonary bypass, arterial pressure and left ventricular (LV) function monitoring. After 20 minutes of normothermic KCl-induced cardiac arrest, animals were resuscitated with cardiopulmonary bypass (120 ml/kg/min) and 100% oxygen. Three minutes after ROSC, the oxygen level was either maintained at 100% for the hyperoxemia group or changed to 40% for the normoxemia group (n = 4/group) for 60 min. Phenylephrine infusion (1.5 μg/kg/min) and intermittent crystalloid fluid (Plasmalyte A) were used during the post-ROSC period to maintain perfusion pressure and bypass flow. Arterial blood gases were measured at baseline and 3, 15, 30, and 60 minutes after ROSC.
Results: The time to ROSC was similar in both groups (hyperoxemia 2.46±0.4 min vs. normoxemia 2.75±0.3 min, NS). At ROSC 10 min, hemodynamics and cardiac function (heart rate, mean arterial pressure, LV dP/dt, rate pressure product and LV negative dP/dt) were not significantly different between groups. However, at ROSC 60 min, the hyperoxemia group had significantly higher LV negative dP/dt (2285±201 vs. 1491±230, p < 0.05), and tended to have higher rate pressure product (21524±1683 vs. 14177±3220, p = 0.09) and LV dP/dt (3201±146 vs. 2415±581, p = 0.22). The PaO2 values in the hyperoxemia group were 441±10 mmHg compared with 107±9 mmHg in the normoxemia group.
Conclusions: In a rat, prolonged cardiac arrest model with cardiopulmonary bypass resuscitation, short-term recovery of cardiac function, particularly diastolic function, was improved with 60 min of hyperoxemia compared to normoxemia.
- © 2010 by American Heart Association, Inc.