From the Guidelines
Target oxygen saturations (SpO2) greater than 90% are generally recommended for seriously ill patients, with a target range of 94-98% for most hypoxaemic patients to ensure that the actual oxygen level remains above 90% for most of the time with a 4% margin of safety. This guideline is based on the British Thoracic Society (BTS) guideline for oxygen use in adults in healthcare and emergency settings 1. The BTS guideline recommends that the SpO2 should be maintained above 90% for seriously ill patients, and a target SpO2 range of 94-98% is suggested for most hypoxaemic patients.
Some key points to consider when targeting oxygen saturations greater than 90% include:
- For patients with chronic obstructive pulmonary disease (COPD) or other risk factors for hypercapnic respiratory failure, a target SpO2 range of 88-92% is recommended pending the availability of blood gas results 1.
- Oxygen therapy should be titrated to achieve these targets using the lowest effective oxygen concentration, starting with low-flow devices like nasal cannulas (1-6 L/min) and progressing to higher flow systems as needed.
- Regular monitoring is essential, as both hypoxemia and hyperoxemia can be harmful, and oxygen saturation should be reassessed frequently, especially after any change in oxygen delivery.
- The presence of a normal SpO2 does not negate the need for blood gas measurements, especially if the patient is on supplemental oxygen therapy, and blood gases and full blood count tests are required as early as possible in all situations where these measurements may affect patient outcomes 1.
Overall, the goal is to maintain oxygen saturation levels that balance the need to prevent hypoxemia with the risk of excessive oxygen exposure, and to individualize oxygen therapy based on the patient's specific condition and response to treatment.
From the Research
Target Oxygen Saturations Greater Than 90%
- The guidelines for target oxygen saturations (SpO2) greater than 90% vary depending on the patient's condition and the medical society's recommendations 2, 3.
- For adult patients without COPD or other conditions associated with chronic respiratory failure, the Thoracic Society of Australia and New Zealand recommends a target SpO2 range of 92-96% 2.
- In contrast, the British Thoracic Society recommends a target range of 94-98% 2.
- However, a study published in 2021 found that in patients with COPD receiving supplemental oxygen, oxygen saturations above 92% were associated with higher mortality, and the adjusted risk of death was higher in the 93%-96% and 97%-100% groups compared to the 88%-92% group 3.
- Another study published in 1999 found that in order to maintain an adequate (> 90%) level of arterial oxygenation in patients with chronic obstructive pulmonary disease and moderate acute respiratory failure, the initial arterial oxygen saturation on oxygen should be maximized whenever possible by increasing the inspiratory oxygen fraction, and the Venturi mask should be recommended over nasal prongs 4.
- A study published in 2021 found that medical patients receiving oxygen in a ward setting spend significant periods of time with SpO2 both above and below the prescribed target range while receiving oxygen therapy, and the proportion of time spent in target range was lower in those with a reduced hypercapnic target range (88-92% or below) compared to those with a range of 92-96% 5.
- A study published in 1990 found that a SpO2 target of 92 percent was reliable in predicting a satisfactory level of oxygenation in white patients receiving mechanical ventilation, but in black patients, such a SpO2 reading was commonly associated with significant hypoxemia, and a higher SpO2 target, 95 percent, was required 6.