Correlation Between Oxygen Saturation and Pulse Tracing Patterns on Overnight Oximetry With Normal Desaturation Index...

Overnight pulse oximetry (OPO) is commonly used as a screening test for obstructive sleep apnea. Heart rate variability (HRV) correlates well with apnea-hypopnea index during polysomnography (PSG). We hypothesized that visual correlation of episodic increase in HRV with minimal oxygen desaturations on normal OPO (oxygen desaturation index less than 5 events/h) is predictive of OSA.

A retrospective analysis of patients undergoing OPO and PSG in 1 year was performed. We included only OPO performed on room air and interpreted as normal. Visual correlation between simultaneous increase in HRV and minimal oxygen desaturation was independently assessed by three raters, resulting in the consensus agreement. The primary outcome was presence of OSA on the subsequent PSG.

Of 936 patients with OPO and PSG, 109 patients had normal overnight oximetry study on room air. Of these, 65 (60%) were females, median (interquartile range) age was 54 years (44, 67), body mass index was 29 kg/m² (25, 32), and the median oxygen desaturation index was 1.8 events/h (1, 2.7). Consensus agreement identified 54 patients with visual correlation between pulse and minimal oxygen desaturations. Thirty-two patients (29%) were found to have OSA on PSG, of which 24 (75%) could have been accurately predicted by the consensus agreement (odds ratio 4.70, 95% confidence interval 1.87-11.8, P < .001). When adjusted for pertinent clinical and demographic variables, consensus agreement was independently associated with diagnosis of OSA on subsequent PSG (odds ratio 5.6, 95% confidence interval 1.76-20.9, P = .003).

Visual correlation between episodic increase in HRV and minimal oxygen desaturations on OPO is an independent predictor of OSA, and promising marker for clinical use.