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.
Age 18 to 65 years.
International commercial flight to Bogota with total airborne time of at least 4 hours.
Preflight baseline ultrasound obtained within 24 hours before departure using the standardized protocol.
Arrival ultrasound completed within 2 hours after reaching the study site and before surgery or intravenous fluid therapy.
Known current deep venous thrombosis or pulmonary embolism.
Therapeutic anticoagulation at enrollment.
Major lower-extremity venous surgery, active leg infection, or condition preventing popliteal ultrasound.
Surgery, prolonged immobilization, or substantial intravenous fluid administration before completion of the 48-hour measurement.
Adult international medical travelers completing a commercial flight of at least 4 hours to Bogota and undergoing all ultrasound measurements before surgery.
Cohort
Prospective
Commercial Air Travel Exposure
Other interventionParticipants complete a commercial flight of at least 4 hours to Bogota. Flight duration, connections, cabin class, seat characteristics, movement, fluid intake, alcohol, sedatives, and compression stocking use will be recorded. Linked arm/group(s): Postflight Repeated-Measures Cohort.
Standardized Bilateral Popliteal Vein Duplex Ultrasound
Diagnostic testAfter at least 10 minutes of supine rest, the popliteal vein will be imaged at a fixed landmark with minimal probe pressure. Anteroposterior and transverse diameters, cross-sectional area, compressibility, and flow will be recorded in both legs, with three repeated measurements averaged. Linked arm/group(s): Postflight Repeated-Measures Cohort.
Change in Mean Bilateral Popliteal Vein Diameter
At each visit, the mean of three anteroposterior diameter measurements in each leg will be calculated, followed by the mean of both legs. Change from the participant's preflight value will be reported in millimeters and as percent change.
Return of Popliteal Vein Diameter to Baseline
Proportion of participants whose mean bilateral diameter is within plus or minus 10% of their preflight value.
Incidental Venous Thrombosis or Abnormal Compressibility
Number and proportion of participants with a new noncompressible venous segment or other finding requiring diagnostic clinical evaluation. This research protocol is not designed as a definitive thrombosis screening examination unless the final duplex protocol is expanded.
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