Until recently, many of those with chronic medical problems were discouraged from heading to the mountains. This has now started to change. People with a range of conditions, from diabetes mellitus to epilepsy and asthma, have found ways to manage the challenges of the mountain environment with enormous success. This has encouraged many others to do the same. From a medical perspective this is brilliant since it encourages us to gain new skills and knowledge that can help more people enjoy the places they love. These thoughts were recently prompted by an email I received from a keen hillwalker who wanted to know whether a recently transplanted kidney was going to be at risk during a forthcoming climb of Kilimanjaro (5895m). In particular, after many years of hypertension she wanted to know if her blood pressure was going to be a problem...
Unfortunately, like many aspects of mountain medicine, there's only a limited amount of evidence to base an opinion on. However in recent years there has been a growing number of published case reports that show healthy and well prepared solid organ recipients have ventured successfully to high altitude.
In order to answer the specific question about the impact of altitude on the blood pressure of those with a transplanted kidney there is published work that sheds some light. Last year a case study in High Altitude Medicine and Biology highlighted the experience of a 57 year old man who 12 years earlier had received a cadaveric transplant after developing end stage renal failure from membranoproliferative glomerulonephritis. More recently, he had been diagnosed with hypertensive cardiomyopathy and treated with losartan and doxasozin. His recovery from surgery had been very good - not only was he back in the mountains within 6 months but he had resumed mountaineering just a year after his surgery. Since the transplant he has climbed above 6000m on several occasions and reached a maximum altitude of 6500m without any difficulties.
Andy Luks' article on high altitude travel following organ transplantation can be found here. It contains lots of fascinating information - not least, the increase in risk of basal cell (x10) and squamous cell (x65) skin cancers amongst organ recipients. This is widely believed to be due to the immunosuppressive medication that is required to prevent organ rejection. Given high levels of UV radiation at altitude it is vital that those taking these drugs cover up and regularly apply high factor (50+) sunscreen to exposed areas of skin
Non invasive blood pressure measurements were obtained regularly at high altitude and sea level. There were plenty of measurements - 1 to 2 per hour - during sleep, rest and exercise - over the course of approximately 48 hours. The first were obtained in Nepal at altitudes of between 2860 and 4300m, whilst the second were taken 15 months later at sea level.
Systolic blood pressure did not increase with altitude exposure and importantly the researchers were unable to identify what they described as "critically high systolic blood pressure measurements (>180mmHg)" at either sea level or high altitude.
Diastolic blood pressure did increase with altitude and rose from a mean of 70.3mmHg to 71.6 (2860-3440m) and 76.7 (3440-4300m). Digging a little deeper, this was largely due to a rise in nocturnal diastolic blood pressure. In fact, mean nocturnal diastolic exceeded daytime measurements. This phenomena is known as "reverse-dipping" and at sea level can be associated with poorer long term outcomes. Whilst the researchers commented that, "the short term significance of this phenomenon at high altitude is unknown", the fact that it was short lived, of a small magnitude and only present at high altitude would suggest that a lasting effect was unlikely.
Whilst a single case can't tell us how a future transplant recipient will cope with high altitude, it does show that it can be done safely and successfully. Using this knowledge as our starting point, we recommended a slow start with exposure to easily accessible areas of moderate altitudes (2500-3500m) in the year leading up to the trip. Weeks spent in the European Alps and North America provided experience of measuring blood pressure and managing anti-hypertensive medication on a mountainside. In addition, it helped answer some key questions that someone with a transplant needs to address before going high in the mountains:
Can I cope with the exercise?
The combination of years of chronic renal failure and a major surgical procedure cannot be underestimated. There's no doubt that physical fitness will be affected. Starting small and building up strength and stamina is vital. Two years on from the transplant, our trekker had made a good recovery and was already doing very well. She had been walking most days with her dogs and working with a fitness instructor at the local gym a couple of times a week. We recommended building longer hill days into her preparation and where possible, linking 2 or 3 days together. At the same time we encouraged her to start wearing the clothing, footwear and equipment that was going to be worn on Kilimanjaro. Nothing should be going to high altitude that hasn't been well used before!
Tacrolimus is commonly used to prevent rejection of transplanted organs. Getting the dose right can take time and close monitoring is required. Like many immunosuppressive drugs interactions are common. Drugs to aid acclimatisation should therefore be avoided. Spare immunosuppressive medications should always be taken to high altitude. This is particularly important with tacrolimus as preparations can vary significantly between different manufacturers. Finding the exact preparation to replace lost supplies may prove very difficult in the mountains!
Can I acclimatise?
Her 2 trips to moderate altitude were invaluable here. Kidneys play a vital part in the acclimatisation process and these trips showed that the transplant could do the job! Spending time between 3000 and 4000m really allows you the chance to see if you have what it takes. Rather than take drug prophylaxis and interfere with the natural acclimatisation process we encouraged the trekker to ascend slowly and take frequent rest days. The recommended ascent rate (500m per day and a rest day every 3 to 4 days) is only a guide and many people need longer. For Kilimanjaro, we recommended an ascent of neighbouring Meru (4562m) first and then a longer 10 day trek on the mountain itself. The Lemosho Glades route is particular good for acclimatisation as it slowly circles the mountain and in the early stages climbs to a highpoint each day before descending to lower altitudes to rest.
Can I minimise my risk of infection?
In order to prevent rejection of a transplanted kidney, the vast majority of recipients take lifelong immunosuppressive drugs. Whilst incredibly effective, they significantly increase the risk of infection. This can be a real problem at high altitude. David Murdoch's landmark study of 283 trekkers to Nepal revealed a staggering 87% that had reported symptoms of infection during their stay! Therefore in discussions with her transplant specialist we ensured that she was up to date with her vaccinations, was prescribed antimalarial prophylaxis and had a "rescue kit" that contained antibiotics and instructions to treat the most common infections. In addition we followed Andy Luks' advice and encouraged her to adopt the following hygiene measures...
Use boiled or bottled water only
Avoid ice in beverages
Do not share drinks with travel partners
Liberal use of hand sanitizer, particularly before meals
Avoid uncooked meats and vegetables
Avoid food sold by street vendors
Avoid fruits that cannot be peeled
With all these questions answered it was time to head to Kilimanjaro!
You'll be glad to know that all went well and future trips to high altitude are now planned!
What happens to your body when you wake up one morning and decide to take a long walk in the mountains? The answer can be found here!
If you would like to find out more about mountain medicine why not join the British Mountain Medicine Society? See this link for details.