rSO2: a Direct Measure of Site-Specific Oxygen
Without the use of cerebral oximetry, adequate brain oxygenation is often inferred by indirect methods such as blood pressure, urine output and finger pulse oximetry. Because these represent systemic - whole body - measures, brain dysfunction and site-specific damage can still occur even when systemic measures are within normal range.
Conversely, the INVOS® System monitors oxygen data specific to the area under the sensor, providing a direct and immediate value of site-specific blood oxygen saturation. Since sensors are placed on each side of the forehead, rSO2 monitoring can detect potential problems at the frontal cortex of the right and left cerebral hemisphere. Similarly, when placed elsewhere on the body, the INVOS® System provides changes in site-specific rSO2 in somatic tissue directly beneath the sensor.
Clinicians use the INVOS® System to get an early warning of site-specific oxygenation changes in order to optimize their patient's outcome and safety. Add the INVOS® System to your existing family of vital signs and receive:
- Real-time detection of site-specific oxygenation issues.
- The ability to immediately see oxygen changes that can trigger timely and targeted interventions such as adjusting anesthesia levels, pump flow, prime, blood products and other factors.
- Immediate feedback on efficacy of interventions taken to correct rSO2 levels.
- Vital information - independent of pulse, blood, pressure and temperature - even in challenging situations such as cardiopulmonary bypass, hypothermic circulatory arrest and treatment of shock and/or cardiovascular collapse.
rSO2: A Valuable Indicator of Cerebral Desaturation
In this case, a dramatic cerebral desaturation occurred early in this off pump coronary bypass (OPCAB). This was associated with a major bleeding event resulting in a severe drop in cerebral oxygen delivery and hematocrit. Conversion to cardiopulmonary bypass allowed the clinicians an opportunity to resuscitate the patient effectively as seen by the rise in rSO2 values. Low oxygen delivery was managed with multiple interventions. Oxygen carrying capacity was increased by adding packed red blood cells. Systemic circulation was supported and improved with pump flow control, adding volume and management of acid base balance. Oxygen content was further increased with hemoconcentration to extract extracelluar fluid. What is most significant and interesting in this case is the lack of change in the traditional hemodynamic parameters. During the resuscitation efforts on CPB, both the SvO2 and MAP remained within normal limits.
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