Characterization of lung to finger circulation time in sleep study assessment: the multi-ethnic study of atherosclerosis.

Introduction 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. Methods 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). 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. 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) sec], p 69 (vs.