Pulse Oximetry Summary Pulse oximetry is the non-invasive continuous measurement of the oxygen saturation of hemoglobin. It exploits the fact that oxy- & deoxy hemoglobin differentially absorb red and infra-red light. Shine Red and IR light through the skin and measure the absorption → DeoxyHb and OxyHb have different light absorption profiles → The signal that varies with time represents the pulsatile blood flow. Using a standard curve, the ratio of Red/IR absorption (modulation ratio) is used to calculate the SaO2 The plethysomograph waveform shows signal over time, corresponding to pulse Amplitude may increase with greater SV (such as after a pause) Perfusion index indicates the signal strength Nick Mark MD @nickmmark #Pulse #Oximetry #Summary #critcalcare #pathophysiology #diagnosis
