Patent ID: 8630708

Claim:
A method of delivering therapy in a medical device, comprising: sensing cardiac signals in a patient; detecting an arrhythmia in response to the signals; delivering an arrhythmia therapy in response to the arrhythmia detection; controlling light emission of a sensor in response to delivering the arrhythmia therapy; detecting emitted light scattered by a tissue volume adjacent the sensor to generate a corresponding detected light intensity output signal; determining a tissue oxygenation measurement in response to the output signal; and determining whether the arrhythmia therapy was successful in restoring cardiac hemodynamic function in response to the tissue oxygenation measurement, wherein computing a tissue oxygenation measurement comprises: computing a second derivative of a light attenuation spectrum measured by the sensor; and computing a measurement of the total hemoglobin volume fraction in response to the second derivative, wherein determining whether the arrhythmia therapy was successful further comprises detecting an increasing trend in a total hemoglobin volume fraction.