Physiologic Venous Dilation

This four-group prospective study will enroll travelers who have independently booked economy or premium business/first-class flights to Bogota. Within each cabin stratum, participants will be randomized to moderate graduated compression stockings or no stockings. Bilateral popliteal vein ultrasound will be performed before flight, within 2 hours after arrival, and at 24 and 48 hours. The primary outcome is the interaction between cabin class and compression assignment for change in mean bilateral popliteal vein diameter.

This prospective cohort study will compare popliteal vein diameter changes in international travelers who independently fly to Bogota in premium business/first class or economy class. Standardized bilateral ultrasound will be performed before flight, within 2 hours after arrival, and at 24 and 48 hours. The primary outcome is the adjusted between-group difference in change from preflight diameter to arrival. Travel behavior and venous-risk confounders will be measured prospectively.

This randomized assessor-masked trial will evaluate whether knee-high moderate graduated compression stockings reduce popliteal vein dilation during long-haul economy-class air travel to Bogota. Participants will be assigned to stockings or no stockings and will undergo bilateral ultrasound before flight, within 2 hours after arrival, and at 24 and 48 hours. The primary outcome is the between-group difference in change in mean bilateral popliteal vein diameter from preflight baseline to arrival.

This prospective repeated-measures study will evaluate how long popliteal vein dilation persists after international commercial air travel to Bogota. Adult medical travelers will undergo standardized bilateral popliteal vein ultrasound within 24 hours before departure, within 2 hours after arrival, and at 24 and 48 hours after arrival, all before surgery. The primary outcome is change in mean bilateral popliteal vein diameter over time.