SaO2 Versus SpO2
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Transcript of SaO2 Versus SpO2
SaO2 versus SpO2SaO2 versus SpO2With background knowledge
Deoxyhaemoglobin (Hb) Oxyhaemoglobin (HbO2) Methaemoglobin (Methb) Carboxyhaemoglobin (COHb) Sulfhaemoglobin (SfHb) Carboxysulfhaemoglobin (COSfhb)
Where the concentration of
oxyhaemoglobin dominates in the blood
Types of haemoglobinsTypes of haemoglobins
A parameter measured by CO-oximeter The ratio of oxyhaemoglobin over all types of
haemoglobin
SaO2SaO2
A parameter measured by pulse-oximeter The ratio of oxyhaemoglobin over the
concentration of oxyhaemoglobin and deoxyhaemoglobin
SpO2SpO2
Traditional way of measuring oxygen saturation in arterial blood
Measurement taken on several wavelengths of light
Achieved with the usage of blood gas analyzer
CO-oximeter CO-oximeter measuring SaO2measuring SaO2
Non-invasive way of oxygen level measurement
Both transmission mode and reflection modes available
Transmission : fingertip, earlobe Reflection : forehead, cheek, calf, thigh Poorer SNR occurs at reflection mode Most-commonly dual-wavelength method
used
Pulse-oximeter Pulse-oximeter measuring SpO2measuring SpO2
Consider a heavy smoker with 15% COhb Pulse-oximeter is unable to distinguish
between COhb and HbO2 In the case where SaO2 is 84%◦ A result of 99% SpO2 will be shown◦ The reading is heavily affected◦ Situation of user endangered when wrong action
taken
Malfunction of pulse-Malfunction of pulse-oximetryoximetry
Measure blood saturation levels. Unable to detect tissue hypoxia as a result of anaemia
Unable to distinguish the dysfunctional haemoglobins – over estimate SaO2 level
Not an accurate devise.. Yet good indicator of saturation and desaturation level
More reliable if reflective probe used to tape to the body
Digital version not necessarily better than analogue one
Summary of pulse oximetrySummary of pulse oximetry
Venous pulsation artificially lower than SaO2 A guide to peripheral circulation Aim to keep levels above 95% Action taken quickly if below 90%
Summary of pulse oximetrySummary of pulse oximetry