Detection of Oxyhemoglobin Desaturation Events is Overestimated by Traditional Low-Resolution Oximeter in Patients with Obstructive Sleep Apnea

Keywords

Sleep apnea - obstructive - hypoxia - pulse oximetry

Introduction: Oxyhemoglobin desaturation events (ODE) are major contributors to the detection and classification of obstructive sleep apnea (OSA). However, variations in pulse oximeter properties, such as resolution, may affect ODE detection and, consequently, the oxygen desaturation index (ODI). We hypothesized that traditional low-resolution pulse oximetry (1%), which rounds decimal points in the readout, overestimates ODE detected by high-resolution pulse oximetry (0.1%).

Objective: To compare the ODI determined by high-resolution pulse oximetry data with the ODI obtained from the same data, mathematically rounded to simulated traditional pulse oximetry.

Methods: Consecutive deidentified diagnostic sleep studies of patients with suspected OSA, recorded between February and June 2023, were extracted from the Biologix database and analyzed. High-resolution pulse oximetry data from the Biologix oximeter (0.1%) was compared with mathematically generated traditional low-resolution pulse oximetry data (1%). ODI differences between high- and traditional low-resolution oximetry were compared using both 3% and 4% oxyhemoglobin desaturation criteria. A confusion matrix and Bland-Altman plot were used to assess the agreement on ODI classifications between high- and traditional low- resolution oximetry.

Results: A total of 9,551 diagnostic sleep studies were analyzed. Compared to the high-resolution oximeter, the traditional low-resolution oximeter overestimated the mean ODI for both 3% (14.3 (6.9–25.3) vs. 21.1 (12.0–34.0)) and 4% (9.1 (3.7–18.0) vs. 13.0 (6.0–23.3)) oxyhemoglobin desaturation criteria (p<0.0001 for both comparisons). Traditional low-resolution oximeter misclassified detection or OSA severity in 40% and 31% of the patients using 3% and 4% oxygen desaturation criteria, respectively (p<0.0001). This overestimation of ODI was not homogeneous across OSA severities and was amplified among patients with no or with mild forms of OSA. Median accuracy was observed between high- and traditional low-resolution oximetry, considering both 3% and 4% oxygen desaturation criteria (60% and 69%, respectively).

Conclusion: Traditional low-resolution pulse oximetry overestimates the number of ODE detected by the high-resolution pulse oximetry due to the embedded rounding algorithm. Since assignment of respiratory events is influenced by the magnitude of oxyhemoglobin desaturation, traditional low-resolution pulse oximetry may overestimate detection and severity of OSA.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
16 September 2025