Hi Marie, It is interesting that I came to this forum today with a similar question. I am making my first international flight after starting warfarin therapy. I also cannot use the self-monitoring device because of Lupus antibodies in my blood.
Currently I am planning to use a medical facility in my destination location that can do pro-time readings several times a week. Based on those readings, my doctor has given me a scale of how much warfarin I should be taking. My largest worry is communicating to the medical facility what information I need and hoping they can do the blood test quickly and effectively.
I would think that your warfarin therapy has been in place long enough that it would not change significantly. My daughter, however, is also on warfarin and has been since March. Her pro-times still reveal irregular results.
My plan, therefore, is to monitor my blood as frequently as I do at home, and to use the scale I have from my doctor to increase or decrease dosage depending on blood levels. I am also going to avoid introducing any additional food items with high concentrations of Vit. K in them while I travel. I am taking lots of Warfarin to use on our trip, which will be about six weeks in length.
If you learn of any other information that could be helpful I would appreciate reading about it as well. Best of luck to you.