Overview
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.
Description
Travelers with documented premium or economy itineraries will be enrolled before departure. Bilateral popliteal vein diameter and cross-sectional area will be measured using a standardized ultrasound protocol before flight and three times after arrival, all before surgery. Actual seat characteristics, flight duration, connections, ambulation, fluid intake, alcohol, sedatives, and compression stocking use will be recorded. Mixed-effects and propensity-weighted analyses will compare the magnitude and persistence of dilation between cabin groups while acknowledging that cabin class is not randomized.
Eligibility
Inclusion Criteria:
- Age 18 to 65 years.
- Commercial flight to Bogota with at least 4 hours of total airborne time.
- Prebooked premium business/first-class or economy-class seat documented before enrollment.
- Standardized preflight ultrasound within 24 hours before departure.
- Arrival, 24-hour, and 48-hour ultrasound completed before surgery.
- Written informed consent.
Exclusion Criteria:
- Current or prior unprovoked deep venous thrombosis requiring therapeutic anticoagulation.
- Therapeutic anticoagulation during the study window.
- Current pregnancy.
- Lower-extremity condition preventing standardized bilateral popliteal ultrasound.
- Surgery, prolonged immobilization, or major intravenous fluid administration before completion of the 48-hour scan.
- Use of cabin upgrade after baseline or inability to verify the actual cabin flown.
