Characterization of lung-to-finger circulation time in sleep study assessment: the Multi-Ethnic Study of Atherosclerosis

Abstract

Objectives: Lung-to-finger circulation time (LFCT) measured from sleep studies may reflect underlying cardiac dysfunction. We aimed to examine the distribution of LFCT in community-dwelling men and women in order to better understand the factors determining LFCT between and within subjects. Approach: We included participants of the Multi-Ethnic Study of Atherosclerosis (MESA) Sleep with polysomnography-based evidence of sleep apnea (defined by apnea hypopnea index >15 hr−1). In a randomly selected subset of the analytical dataset, we tested an automated LFCT measurement method against the visual method. Using the automated method we then scored LFCTs from all eligible respiratory events for all included participants. A multiple regression model was constructed to determine factors independently associated with average LFCT across subjects. We also explored factors that are associated with LFCT within subjects using linear mixed-effect models. Main results: In a subset of the cohort (N = 39) there was a high correlation in average LFCT obtained by automated and visual methods (r = 0.96). In the analysis of 596 participants, men [19.6 (2.8)] (vs. women [17.9 (2.7) s], p < 0.0001) and older age (> 69 (vs. ≤ 69) had longer average LFCT (19.4 [2.8] vs. 18.5 [2.9] s, p < 0.0001). These associations persisted in multivariable analysis. No association was found with body habitus. Within subject analysis revealed trivial associations between apnea/hypopnea duration, apnea (vs. hypopnea), nadir O2 saturation and sleep stages (NREM vs. REM) and individual LFCT. Significance: Automated LFCT measurement was highly correlated with visual-based LFCT measurement. In this group of community-dwelling adults, male sex and older age were associated with higher average LFCT.

Prolonged lung-to-finger circulation time indicates an increased risk of intermittent hypoxaemia in sleep apnoea patients

“…Importantly, previous studies have reported that LFCt and hypoxic burden can be used as significant predictors for cardiovascular disease and mortality [ 19 , 24 ]. Furthermore, we observed a trend of prolonged LFCt in obese and older patients, which is also consistent with previous findings [ 10 , 24 , 26 ]. It is known that obesity is directly associated with haemodynamic overload and a decrease in cardiac output occurs with age, which might explain the trend of prolonged LFCt in obese and older patients [ 27 , 28 ].…”

“…Additionally, severe hypoxaemia in patients with OSA has also been associated with increased heart rate, cardiac response and severe cardiovascular diseases [ 16 , 20 ]. Moreover, previous studies have demonstrated that LFCt has the potential to be used as a marker for cardiovascular health and comorbidities in sleep studies [ 8 , 24 , 26 ]. Therefore, although our study alone does not suffice to fully determining the clinical utility of LFCt with respect to cardiac impairment; the LFCt distribution reported in the present study showed that hypoxic severity can be significantly elevated even with short apnoeas, which has considerable implications for cardiac health prognosis in patients with OSA.…”

Systems Engineering Approach to Modeling and Analysis of Chronic Obstructive Pulmonary Disease Part II: Extension for Variable Metabolic Rates

“…The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.3c05953. The Simulink file used in this work may be obtained from the corresponding author on reasonable request. The following additional works are referred to in the Supporting Information − Model equations, parameters, and the method for simulating the spirometry test (PDF) …”

“…The Simulink file used in this work may be obtained from the corresponding author on reasonable request. The following additional works are referred to in the Supporting Information − …”