Date Published: September 1, 2017
Publisher: Public Library of Science
Author(s): Lukas Ruzek, Karolina Svobodova, Lyle J. Olson, Ondrej Ludka, Ivan Cundrle, Andrea Romigi.
Obstructive sleep apnea (OSA) is the most common form of sleep disordered breathing and has been associated with major cardiovascular comorbidities. We hypothesized that the microcirculation is impaired in patients with OSA and that the magnitude of impairment correlates to OSA severity.
Subjects were consecutive patients scheduled for routine diagnostic polysomnography (PSG). OSA was defined by paradoxical rib cage movements together with abdominal excursions and by the apnea-hypopnea index (AHI) (events/hour; no apnea AHI<5; mild apnea 5≤AHI<15; moderate apnea 15≤AHI<30; severe apnea AHI ≥30). Sidestream darkfield imaging was used to assess the sublingual microcirculation. Recordings of sublingual microcirculation (5 random sites) were performed before and after overnight PSG. Data are summarized as mean (±SD); p values <0.05 were considered statistically significant. Thirty-three consecutive patients were included. OSA was diagnosed in 16 subjects (4 moderate, 12 severe). There was no significant difference in microcirculation between subjects with moderate OSA and without OSA. However, compared to subjects without OSA, subjects with severe OSA (AHI≥30) showed a significant decrease of microvascular flow index (-0.07±0.17 vs. 0.08±0.14; p = 0.02) and increase of microvascular flow index heterogeneity (0.06±0.15 vs. -0.06±0.11; p = 0.02) overnight. Multiple regression analysis (adjusted for age and gender) showed both decrease of flow and increase of flow heterogeneity associated with AHI (b = -0.41; F = 1.8; p = 0.04 and b = 0.43; F = 1.9; p = 0.03, respectively). Acute overnight microcirculatory changes are observed in subjects with severe OSA characterized by decreased flow and increased flow heterogeneity.
Obstructive sleep apnea (OSA) is the most prevalent form of sleep disordered breathing in the community . OSA is characterized by recurrent cessation of breathing during sleep and has been associated with major cardiovascular comorbidities including systemic and pulmonary hypertension, heart failure, myocardial infarction, stroke as well as increased mortality rates [2–4]. The mechanisms linking OSA and cardiovascular diseases are not fully understood .
Thirty-three consecutive patients were included, from whom 320 video sequences were analyzed. Subject characteristics are shown in Table 1. Compared to subjects without OSA, subjects with severe OSA had significantly higher BMI. Otherwise there were no significant differences in age, number of males, number of smokers, morning time to SDF measurements, frequency of major chronic illnesses, or cardiovascular medication between the groups.
The major finding of this pilot study was that microcirculatory changes were present only in subjects with severe OSA and were characterized by an overnight decrease of flow and increase of flow heterogeneity.
Microcirculatory changes are observed only in subjects with severe OSA and are characterized by overnight decreased flow and increased flow heterogeneity.