Weighted Hypoxemia Index: An adaptable method for quantifying hypoxemia severity

by Diane C. Lim, Cheng-Bang Chen, Ankita Paul, Yujie Wang, Jinyoung Kim, Soonhyun Yook, Emily Y. Kim, Edison Q. Kim, Anup Das, Medhi Wangpaichitr, Virend K. Somers, Chi Hang Lee, Phyllis C. Zee, Toshihiro Imamura, Hosung Kim

To quantitate hypoxemia severity.

We developed the Weighted Hypoxemia Index to be adapted to different clinical settings by applying 5 steps to the oxygen saturation curve: (1) Identify desaturation/resaturation event i by setting the upper threshold; (2) Exclude events as artifact by setting a lower threshold; (3) Calculate weighted area for each i, as (Δi × Φi); (4) Calculate a normalization factor Ω for each subject; (5) Calculate the Weighted Hypoxemia Index as the summation of all weighted areas multiplied by Ω. We assessed the Weighted Hypoxemia Index predictive value for all-cause mortality and cardiovascular mortality using the Sleep Heart Health Study (enrollment 1995–1998, 11.1 years mean follow-up).

We set varying upper thresholds at 92%, 90%, 88%, and 86%, a lower threshold of 50%, calculated area under the curve and area above the curve, with and without a linear weighted factor (duration of each event i), and used the same normalization factor of total sleep time Conclusion

The Weighted Hypoxemia Index offers a versatile and clinically relevant method for quantifying hypoxemia severity, with potential applications to evaluate mechanisms and outcomes across various patient populations.