Accuracy of Pulse Oximeters in Detecting Hypoxemia in Patients with Chronic Thromboembolic Pulmonary Hypertension

Abstract

Purpose

Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO ₂). When oxygen saturation by pulse oximeter (SpO ₂) overestimates SaO ₂, hypoxemia may be overlooked. We compared the SpO ₂ - SaO ₂ differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who spent their daily lives in a poor oxygen state.

Material and Method

This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO ₂ values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO ₂ values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO ₂ value by which to detect hypoxemia (SaO ₂≦90%), we generated receiver operating characteristic (ROC) curves for each pulse oximeter.

Result

The root mean square of each pulse oximeter was 1.79 (OLV-3100), 1.64 (N-BS), and 2.50 (Masimo Radical). The mean bias (SpO ₂ - SaO ₂) for the 90%–95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001). The optimal SpO ₂ value to detect hypoxemia (SaO ₂≦90%) was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical.

Conclusion

We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO ₂ should be determined for each pulse oximeter.