KEY POINTS:
In June the World Health Organisation released the results of a study entitled "Global Hazards of Travel". The results confirmed that the risk of developing a deep vein thrombosis and possibly a pulmonary embolism doubles after air travel lasting four hours or more.
Those passengers taking multiple flights over a short period of time were found to be at an even higher risk.
It was also determined that the risk remained elevated for up to four weeks after each flight.
A deep vein thrombosis (DVT) is a condition in which a blood clot develops in a deep vein - usually in the lower leg. Symptoms include pain, tenderness and swelling to the affected part of the leg.
It can be detected through testing and treated. But it can become life-threatening when it is associated with pulmonary embolism (PE) which occurs when the blood clot in a leg vein breaks off and travels through the body to the lungs where it becomes lodged and blocks blood flow. Symptoms include chest pain and breathing difficulties. If not treated, PE can lead to death.
On June 25, before the WHO warning, I suffered a deep vein clot in my left calf while on a 15-hour multi-leg flight from Australia to Los Angeles. I thought I was immune to such a medical catastrophe.
After all, I was an endurance athlete who had completed more than 20 Ironman triathlons. I had also taken part in numerous adventure races, including a 30-day, 3200km event covering the length of New Zealand. I was just returning from an intensive training camp in Queensland. My resting heart rate was in the low 40s and my blood pressure in the low range.
Airhealth, an organisation collating reports from passengers on the medical risk of air travel, recently suggested that 85 per cent of air travel thrombosis victims are athletic, usually endurance-type athletes such as marathoners or Ironman participants.
These are the people with slower-resting blood flow who are at greater risk for stasis, which is stagnant blood subject to clotting. They are also more likely to have bruises and sore muscles that can trigger clotting.
Airhealth claims that no other risk factors for air travel DVT come closer than being athletic. Although advancing age is supposed to be a risk factor, 80 per cent of passengers reporting a DVT or PE episode were under 60.
I have since discovered I did everything wrong on my flight from Australia. I slept non-stop for eight hours and obviously did not hydrate or exercise my legs.
I sat in a window seat and was so jammed in by the large passenger sitting in the aisle seat and squashed by the reclined seat backs in front of me that I did not get up and walk around the plane when I was awake.
So, what happened to make me recognise I had suffered a deep vein thrombosis? Initially, I had no clue. The injury often feels like a muscle cramp and is usually misdiagnosed, thereby aggravating the injury and increasing the risk of permanent disability or death.
This pain may not start until days after the flight. In my case, I returned to my San Diego base by driving down from Los Angeles. When I got out of the car I noticed I was limping and my calf was swollen. To shake things out I went for a short run - wrong.
That night my calf was throbbing and tender. By the next day I knew this was something different. A niggling in the back of my mind made me research thrombosis on the internet. Bingo, I had the classic symptoms of a DVT in my left calf (it is usually the left calf, because of the way a major artery passes over and presses on a major vein in the left leg).
A call to my doctor had me immediately sent to the local hospital. There I had an ultrasound, which confirmed a blood clot. The treatment that followed consisted of medicated blood thinners, compression stockings and lots of enforced rest with my leg elevated.
I was lucky; a blood clot behind or above the knee carries a much greater chance of the clot breaking away and moving to the lung to create a pulmonary embolism. In addition, all my blood tests for susceptibility to hereditary blood clotting factors came back negative (these blood factors, if positive, can increase the risk of blood clotting exponentially).
So, what is my prognosis? I will be on blood thinners and wearing compression stockings for some time. I seemed to have dodged the immediate bullet of a PE but need my body to work its natural lysis (diminution) of the clot.
Then I should be back to normal training and ready for Ironman next year. Of course, in the worst-case scenario, I could end up with post-thrombotic syndrome (PTS) where the clot does not dissipate and the blood refluxes down to my foot and causes such long-term ailments as varicose veins, ulcers, or worse.
So do not take the risk of a DVT lightly when planning a long-distance flight. Medical journals report that during air travel, blood flow slows and coagulability rises. Reasons for this include the high cabin altitude and the low humidity, which causes dehydration.
Experts recognise that blood circulation can be promoted by:
* Exercising the calf muscles with up and down movements of the feet at the ankle joints.
* Simple recommended steps include not wearing tight clothing, knee braces etc.
* Wear compression stockings which extend to the knee.
* Do not take sleeping pills or drink alcohol or coffee. Stay properly hydrated.
* Sleep for short intervals only and keep feet elevated, if possible.
Acknowledgements: World Health Organisation announcement (June 29, 2007); Airhealth.org (www.airhealth.org)
