Pulse oximetry measures what?

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Multiple Choice

Pulse oximetry measures what?

Pulse oximetry measures the percentage of hemoglobin that is saturated with oxygen in arterial blood. It uses two wavelengths of light to distinguish oxyhemoglobin from deoxyhemoglobin and derives SpO2 from the pulsatile arterial signal, indicating how much of the hemoglobin is carrying oxygen. Dissolved oxygen in plasma is not what pulse oximetry assesses; that amount is negligible and is reflected by the arterial oxygen content and PaO2 on an arterial blood gas. Partial pressure of oxygen is a pressure value of dissolved O2, not the saturation level; pulse oximetry reports how much hemoglobin is bound with oxygen, not the exact gas pressure. Oxygen-carrying capacity depends on both how much hemoglobin you have and how saturated it is; pulse oximetry only tells you the saturation fraction, not the total Hb amount.

Pulse oximetry measures the percentage of hemoglobin that is saturated with oxygen in arterial blood. It uses two wavelengths of light to distinguish oxyhemoglobin from deoxyhemoglobin and derives SpO2 from the pulsatile arterial signal, indicating how much of the hemoglobin is carrying oxygen.

Dissolved oxygen in plasma is not what pulse oximetry assesses; that amount is negligible and is reflected by the arterial oxygen content and PaO2 on an arterial blood gas. Partial pressure of oxygen is a pressure value of dissolved O2, not the saturation level; pulse oximetry reports how much hemoglobin is bound with oxygen, not the exact gas pressure. Oxygen-carrying capacity depends on both how much hemoglobin you have and how saturated it is; pulse oximetry only tells you the saturation fraction, not the total Hb amount.

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