Abstract
Intermittent hypoxemia is closely associated with cardiovascular dysfunction and may be a more accurate indicator of OSA severity than conventional metrics. Another key factor is the lung-to-finger circulation time (LFCt), defined as the duration from the cessation of a respiratory event to the lowest point of oxygen desaturation. LFCt serves as a surrogate marker for circulatory delay and is linked with cardiovascular function. Yet, the specific associations between respiratory and hypoxemia characteristics and LFCt in OSA patients remain unclear. This study aims to investigate these associations, ultimately contributing to a more nuanced understanding of OSA severity.
The study comprised 878 in-lab polysomnographies of patients with suspected OSA. The conventional OSA metrics were computed along with nine hypoxemia metrics and then divided into quartiles (Q1-Q4) based on respiratory event duration. In addition, these were further divided into sub-quartiles based on LFCt. The empirical cumulative distribution functions (CDFs) and linear regression models were used to investigate the association between desaturation metrics and LFCt.
The results showed that prolonged LFCt was associated with increased hypoxic severity. Based on CDFs, the hypoxic severity significantly increased with longer LFCt despite the duration of respiratory events. Furthermore, fall duration was elevated in patients with longer LFCt (Q1-FallDur:14.6 s; Q4-FallDur:29.8 s; p<0.0001). The regression models also showed significant association between hypoxic severity and LFCt (Q1-FallSlope: β=−3.224; Q4-FallSlope: β=−6.178; p<0.0001).
Considering LFCt along with desaturation metrics might be useful in estimating the association between the severity of OSA, physiological consequences of respiratory events, and cardiac health.
Footnotes
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Conflict of interest: None of the authors have any conflicts of interest to report.
Conflict of interest: Purbanka Pahari, Henri Korkalainen, Timo Leppänen, and Sami Nikkonen disclose State Research Funding from the Research Committee of the Kuopio University Hospital Catchment Area for the State Research Funding Research Committee of the Kuopio University Hospital Catchment Area for the State Research Funding (projects 5041767, 5041794, 5041805, and 5041803). Juha Töyräs, Timo Leppänen, and Erna Sif Arnardottir disclose research funding from NordForsk (NordSleep project 90458). Erna Sif Arnardottir, Timo Leppänen, Henri Korkalainen, Anna Sigridur Islind, Elias August, and Juha Töyräs disclose research funding from the European Union's Horizon 2020 Research and Innovation Programme (grant 965417). Juha Töyräs and Timo Leppänen disclose project funding from National Health and Medical Research Council (NHMRC), Australia. Purbanka Pahari also discloses a personal grant from the Respiratory Foundation of Kuopio Region. Erna Sif Arnardottir discloses lecture fees from Nox Medical, Philips, ResMed, Jazz Pharmaceuticals, Linde Healthcare, Alcoa Fjardaral, and Wink Sleep. Erna Sif Arnardottir is also a member of the Philips Sleep Medicine and Innovation Medical Advisory Board. Arie Oksenberg has no conflicts of interest.
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- Received February 5, 2024.
- Accepted March 6, 2024.
- Copyright ©The authors 2024
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