Jeremy Windsor / Consultant in Anaesthetics and Intensive Care Medicine / Chesterfield Royal Hospital, Derbyshire, England
As well as a consultant anaesthetist and intensivist, Jeremy Windsor has been involved in climbing and mountaineering expeditions for more than twenty years. In 2007 he climbed Mt Everest as part of the Caudwell Xtreme Medical Research Expedition. He has completed an MD in high altitude medicine and written more than a hundred abstracts, book chapters and research papers on the subject. In this article, Jeremy questions how transplant patients’ physiology is affected by high altitude, and the steps that can be taken to mitigate against the risks in these patients.
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 now found ways to manage the challenges of the mountain environment with enormous success which has only encouraged many others to do the same. From a medical perspective, initially this is a very positive step as it encourages expedition medics to gain new skills and knowledge, whilst facilitating a greater number of people who are safely able to enjoy the wildest of places.
I began pondering the management of complex and chronic medical problems on expeditions recently when I was prompted by an email I received from a keen hillwalker who wanted to know whether her 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 exists only limited evidence on which to base important decisions in a variety of very specific situations. 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 glomerulonephritis1. 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; both at sea-level and at high-altitude in Nepal (between altitudes of 2860 – 4300m). One to two measurements were taken per hour – during sleep, rest and exercise – over the course of approximately 48 hours. Systolic blood pressure did not increase with altitude exposure and more 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. However, 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 cannot 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 gradual progression to altitude, with exposure to easily accessible areas of moderate altitudes (2500-3500m) in the year leading up to the trip. This study also helped to address a few key questions that transplant recipients may have before going on expeditions to the high mountains:
1. Can I cope with the exercise?
The combination of years of chronic renal failure and major surgical procedures cannot be underestimated. There is no doubt that physical fitness will be affected. Starting small and gradually 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. No kit should be traveling to high altitude if it’s not been 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, and finding the exact preparation to replace lost supplies may prove very difficult in the mountains!
2. Can I acclimatise?
Our trekker’s two previous trips to moderate altitude proved invaluable in this case. Kidneys play a vital part in the acclimatisation process and these prior trips to 3000 – 4000m altitude showed that the transplant could do the job. Rather than taking prophylactic medication which may interfere with the body’s 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 – 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 a particularly good option for acclimatisation as it slowly circles the mountain and in the early stages climbs to a high-point each day before descending to lower altitudes to rest.
3. 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, these significantly increase the risk of infection which can be a real problem at high altitude. David Murdoch’s landmark study of 283 trekkers in Nepal revealed that a staggering 87% had reported symptoms of infection during their stay2. Therefore in discussions with her transplant specialist we ensured that our patient was up to date with her vaccinations, 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; safe in the knowledge of our training, preparation in altitude acclimatisation!
References
- Travel to High Altitude Following Solid Organ Transplantation. Luks, AM. 2016. High Altitude Medicine & Biology. 17(3). URL: https://www.liebertpub.com/doi/abs/10.1089/ham.2016.0060
- Symptoms of infection and altitude illness among hikers in the Mount Everest region of Nepal. Murdoch, DR. 1995. Aviat Space Environ Med. 66(2):148-51. URL: https://pubmed.ncbi.nlm.nih.gov/7726779/
📷 Images provided by: Alex Taylor, Instagram: @alex_expeditionmedic
Links
As well as his day-job and background in altitude medicine research, Jeremy is also co-founder of the Hathersage Mountain Medicine Festival and in 2018 launched the Anaesthetics, Critical Care and Mountain Medicine Fellowship at Chesterfield Royal Hospital.
And as if that wasn’t enough, Jeremy also runs his own website and educational Mountain Medicine Blog; ‘Surviving the death zone’; writing and publishing a regular articles covering a variety of interesting expedition medicine topics.
