Enhancing cerebral safety: the routine use of regional cerebral oxygen saturation monitoring during cardiopulmonary bypass operations using the invos 3100 cerebral oxymeter

ABSTRACT

Over a 16 months period, a total of 200 patients were monitored using the Invos 3100 cerebral oxymeter measures regional saturation [rSO2] of cerebral microvasculature. From arrival in the operating room rSO2 was recorded along with all normal monitoring parameters in cardiac surgery, viz patient temperature, blood pressure, central venous pressure, arterial and venous blood gases [VBG]. End-tidalpCO2, inspired oxygen concentration and pump flow. Thirty-four patients [group I], had complete date, 166 patients [group II] did not have VBG done and a subset of 12 group II patients [group III] had rSO2, mean arterial pressure, pump flow and temperature measured every 205 minutes on bypass. No significant correlations could be found between rSO2 and any of these parameters, apart from mean arterial pressure on bypass at nasopharyngeal temperatures below 34°C in group III patients. Monitoring was continued on the intensive care unit until extubation or for the first 24 hours in 183 patients and results were similar. These findings support the contention that monitoring of rSO2 yields unique information, not available with other monitoring systems. Our experience with the routine use of rSO2 monitoring suggests that systems of this type are a valuable adjunct to conventional monitoring. In specific patients,rSO2gave early warning of cerebral circulatory inadequacy due to venous obstruction, was used to monitor the efficacy of cardiopulmonary resuscitation and determine the need for shunting in carotid endarterectomy