# Intermittent hypoxia index: a new indicator for assessing the degree of intermittent hypoxia in obstructive sleep apnea

## TL;DR

This paper introduces a new index called IHI to better assess the severity of intermittent hypoxia in obstructive sleep apnea patients.

## Contribution

The novel intermittent hypoxia index (IHI) is proposed as a comprehensive and quantifiable measure of nocturnal hypoxia in OSA.

## Key findings

- IHI showed strong correlations with T90 (r = 0.922) and LSpO2 (r = 0.866), and moderate with ODI (r = 0.675).
- A threshold of 7.178 (%s/min) was determined for diagnosing hypoxia using IHI in OSA patients.
- IHI is a new comprehensive index that covers multiple dimensions of intermittent hypoxia.

## Abstract

In order to objectively and accurately evaluate the degree of nocturnal intermittent hypoxia (IH) in patients with obstructive sleep apnea (OSA), we developed the Newton quadrature low oxygen load assessment system (NLAS) to seek a new, quantifiable, comprehensive evaluation index of intermittent hypoxia (intermittent hypoxia index, IHI).

Demographic characteristics, anthropometric measurements, and polysomnography (PSG) parameters [oxygen desaturation index (ODI), lowest oxygen saturation (LSpO2), time below 90% saturation (T90)] of 732 patients with OSA who underwent multi-channel sleep monitoring at the Sleep Center of Affiliated Wuxi People’s Hospital, Nanjing Medical University, from 2019 to 2023 were retrospectively collected. The IHI was calculated using the NLAS (Certificate of Registration Number for Computer Software Copyright of the People’s Republic of China: 12208933), and its threshold was defined. Additionally, correlation analysis was performed between IHI and T90, LSpO2, and ODI.

Among the 732 patients with OSA, IHI showed significant correlations with T90 (r = 0.922) and LSpO2 (r = 0.866), and moderate correlation with ODI (r = 0.675). The threshold for diagnosing hypoxia in OSA patients using IHI was 7.178 (%s/min).

This study demonstrates that IHI calculated using NLAS covers various dimensions of IH indices in OSA patients undergoing multi-channel sleep monitoring. It correlates with parameters such as T90, LSpO2, and ODI. Independent of existing IH assessment indices, IHI holds promise as a new comprehensive assessment index for evaluating the degree of nocturnal IH in OSA.