A trip to Nepal and a trek to Everest. What a neat goal. Good for you!
As far as traveling at higher altitudes I think that your main concerns would be the same as anyone going quickly from sea-level to a higher elevation. You need to be fit for the challenge and acclimate at increasingly higher elevations to reduce the potential for mountain sickness. Avoid unsanitary food and water while traveling to avoid "you know what" which will dehydrate you and make life miserable, stay hydrated, have good clothes that protect you from the elements including cold, wind, and sun exposure.
As far as INR, you might want to have a backup supply of warfarin and keep it in watertight containers. Maybe have a friend carry some as a backup. Take a few syringes in case you need an injection in a third-world country where clean needles may be rare.
You may want to shift your diet to match your expected diet while traveling in order to adjust your warfarin dose and stabilize your INR before you leave.
Surprisingly high altitude
can affect clotting factor levels as explained in the snippet I've included below.
Here is the link. You might want to follow up and read the listed citations.
Also see this discussion on INR and
travel to Nepal.
Have a great trip. Please keep us informed and post pictures when you return.
John
From
www.FVLeiden.org Thrombophilia Awareness Project
Ask Dr. Stephan Moll
These questions have been submitted by folks on the mailing list and answered by Dr. Moll, Director of the Thrombophilia Program at the Carolina Cardiovascular Biology Center, Department of Medicine, Division of Hematology-Oncology, UNC Chapel Hill (North Carolina, USA)
110. High Altitude and Clotting Risk Last Updated: 3/5/2008
Q: "I'm leaving for South America in late March and will be visiting several locations at high altitude (8,500 to13,500 feet, i.e. 2800-4,500 meters). I have had a pulmonary embolism in the past and am on long-term warfarin. I plan to acclimate myself at lower altitude for a few days and then proceed. A question has been raised from my two doctors. One is suggesting I don't proceed because of past PEs and the other doctor is investigating the effects of high altitude on maintaining proper INR with coumadin. Currently, I'm on 9 mg of warfarin per day to maintain an INR of 2.0 to 2.5. My vitamin K consumption is normally high. But considering the areas where I plan to travel (primarily in Peru and in the Andes), I realize that my intake of greens may be limited due to sanitary issues.
Therefore, the two questions I have are
(1) What is the affect of high altitude on clotting of individuals with clotting disorders; and
(2) What are the affects of high altitude on warfarin and INR levels when one considers that Vitamin K intake will be reduced from normal levels.
A to Question 1: It has been shown that clotting factor levels change in unacclimatized individuals who travel to high altitude (4000-5000 meters, i.e. 12,000-15,000 feet) for short-term stays: an increased tendency to clot is suggested by increased blood levels of so-called "PAI-1 levels" and "prothrombin fragment 1+2" 1, as well as increased "D-dimer" levels 2. Similarly, in individuals who are at high altitude for a prolonged period of time, an increased clotting tendency is suggested by abnormal laboratory findings (elevated PAI-1 levels) 3. Whether this leads to a higher risk of deep vein thrombosis and pulmonary embolism is not well established. Furthermore, whether the individual who has had a thrombotic event and who is now on therapeutic levels of warfarin (i.e. INRs in the therapeutic range) is at any increased risk for clots while at high altitude is also not known.
A to Question 2: (a) Traveling to high altitude can lead to INR instability. The INR decreases in a number of patients: in one study, 60 % of patients ascending to altitude (> 2400 meters, i.e. > 7,200 feet) developed an INR decrease of an average of 0.7 INR units 4. (b) If vitamin K intake is significantly reduced due to dietary changes, one would expect that the INR may increase if the dose of warfarin is kept unchanged.
Conclusion: Firstly, if an individual who is on warfarin because of a history of thrombosis decides after consultation with his/her physician to travel to high altitude, it would be optimal for the INR to be closely monitored. However, this may logistically not be possible, unless the individual has a device-monitor for INR self testing. Secondly, if a person expects to have a significantly lower vitamin K intake while traveling, it may be reasonable to consider taking daily vitamin K supplementation of ca. 100 micro gram of vitamin K per day while traveling, to balance out the decreased intake of vitamin K with food.. However, this should be discussed with the patient's anticoagulation provider. Furthermore, it would be best to have some way to determine what the INRs are during such dietary change and vitamin K supplementation.
References:
1. Mannucci PM, Gringeri A, Peyvandi F, Di Paolantonio T, Mariani G. Short-term exposure to high altitude causes coagulation activation and inhibits fibrinolysis. Thromb Haemost 2002; 87:342-3.
2. Le Roux G, Larmignat P, Marchal M, Richalet JP. Haemostasis at high altitude. Int J Sports Med 1992; 13 Suppl 1:S49-51.
3. Kotwal J, Apte CV, Kotwal A, Mukherjee B, Jayaram J. High altitude: a hypercoagulable state: results of a
prospective cohort study. Thromb Res 2007; 120:391-7.
4. Van Patot MC, Hill AE, Dingmann C, et al. Risk of impaired coagulation in warfarin patients ascending to
altitude (>2400 m). High Alt Med Biol 2006; 7:39-46.
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