Background: Pulse oximetry is widely used in the clinical setting. The purpose of this validation study was to investigate the level of agreement between oxygen saturations measured by pulse oximeter (SpO2) and arterial blood gas (SaO2) in a range of oximeters in clinical use in Australia and New Zealand.
Methods: Paired SpO2 and SaO2 measurements were collected from 400 patients in one Australian and two New Zealand hospitals. The ages of the patients ranged from 18 to 95 years. Bias and limits of agreement were estimated. Sensitivity and specificity for detecting hypoxaemia, defined as SaO2 < 90%, were also estimated.
Results: The majority of participants were recruited from the Outpatient, Ward or High Dependency Unit setting. Bias, oximeter-measured minus arterial blood gas-measured oxygen saturation, was - 1.2%, with limits of agreement - 4.4 to 2.0%. SpO2 was at least 4% lower than SaO2 for 10 (2.5%) of the participants and SpO2 was at least 4% higher than the SaO2 in 3 (0.8%) of the participants. None of the participants with a SpO2 ≥ 92% were hypoxaemic, defined as SaO2 < 90%. There were no clinically significant differences in oximetry accuracy in relation to clinical characteristics or oximeter brand.
Conclusions: In the majority of the participants, pulse oximetry was an accurate method to assess SaO2 and had good performance in detecting hypoxaemia. However, in a small proportion of participants, differences between SaO2 and SpO2 could have clinical relevance in terms of patient monitoring and management. A SpO2 ≥ 92% indicates that hypoxaemia, defined as a SaO2 < 90%, is not present.
Trial registration: Australian and New Zealand Clinical Trials Registry (ACTRN12614001257651). Date of registration: 2/12/2014.
Keywords: Arterial blood gas; Hypoxaemia; Oxygen; Pulse oximeter; Validation.