Circulating Vascular Endothelial Growth Factor Levels in Patients with Obstructive Sleep Apnea

Abstract

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is associated with intermittent hypoxia during sleep. Vascular endothelial growth factor (VEGF) has detectable levels in the circulation and its expression is highly regulated by oxygen tension. We therefore hypothesized that serum VEGF levels will be elevated in patients with OSA. DESIGN: Blood samples were collected at random times during the day from 68 adults and 41 children who were clinically suspected for the presence of OSA, and who underwent overnight polysomnography. SETTING: University hospital sleep laboratory. PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: For both children and adults, serum VEGF levels were significantly higher in polysomnographically confirmed OSA (AHI>15 and AI>5 in adults and children respectively) when compared to those with mild or no disease (p<0.0001). Furthermore, significant correlations were found between VEGF concentrations and respiratory disturbance index and sleep time spent at SpO2 <90%. In addition, VEGF levels in children were higher for any given duration of hypoxia during sleep (p<0.0001). No differences in VEGF emerged between evening and morning samples. However, temporal delays in blood sample processing were associated with spuriously increased VEGF concentrations. Exploratory analysis of the data revealed that serum VEGF concentrations of >150 pg/ml in adults and >100 pg/ml in children were predictive of OSA, when an apnea-hypopnea index >30 and an apnea index >5 were used as disease criteria in adults and children, respectively. CONCLUSIONS: We conclude that circulating VEGF levels are frequently elevated in OSA patients, and may play a role in the regulation of tissue oxygen delivery.