Pulse oximetry to monitor acute oxygen therapy

Monitor acute oxygen therapy with continuous pulse oximetry. Document the delivery system and flow rate, as well as the target oxygen saturation measured by pulse oximetry (SpO₂). Alter the oxygen flow rate to keep SpO₂ within the target range.

Target oxygen saturation levels may be different for children in some clinical situations (eg cyanotic congenital heart disease, severe chronic lung disease)—seek specialist advice.

The target SpO₂ is generally 92 to 96% unless the patient has a condition that results in chronically lower SpO₂ or risk of hypercapnia.

For patients at risk of hypercapnia , use a lower target SpO₂ of 88 to 92%; however, in critically ill patients, the standard target (SpO₂ 92 to 96%) may be used initially, pending results of arterial blood gas analysis.

Pulse oximetry has several limitations:

• It measures only oxyhaemoglobin saturation, not oxygenation or ventilation.
• It does not measure carbon dioxide levels; arterial blood gas analysis is needed to quantify hypercapnia¹.
• Readings may be misleading in some clinical scenarios; for example, they will be misleadingly low with hypoperfusion, but falsely high in carbon monoxide poisoning, and falsely reassuring in cyanide poisoning and severe anaemia (the measured SpO₂ is correct, but oxygen is not available to tissues). See Pulse oximetry for more factors that can affect accuracy of pulse oximetry.