Dr Jake Warrington / Sheffield / Emergency Medicine Junior Clinical Fellow
Vivienne Mathews / Scotland / Medical Student
Dr Constance Osborne / London / Evidence Explorer Lead
Contents
- Introduction and Collaborators
- Expedition and Wilderness Medicine Section
- Global Health and Humanitarian Medicine Section
- Want to get involved?
Thank you for joining us once again at the Evidence Explorer. As an academic amuse-bouche, we’re opening this edition with an FAQ page on ‘Women at Altitude’. This piece was written by members of the UIAA Medcom, who undertook a large scale evaluation of medical evidence on women’s health at altitude. They presented their work earlier this year at the International Society of Mountain Medicine Congress held in Utah. If you would like to peruse a more detailed review of the topic, it can be found in the journal of ‘High Altitude Medicine and Biology’.
Now, onto the main course! The articles in this edition were selected and appraised by our wonderful collaborators over the course of the summer.
Dr Jake Warrington is a FAWM certified doctor currently living and working in Sheffield, where he is completing an emergency medicine fellowship. When not at work, he can be found in the Peak District with his young family. His interests include trad climbing, cycling, surfing, paddleboarding and woodworking. He spends winter weekends attempting to tick off different icy routes up Ben Nevis.
Vivienne Mathews is a medical student in Scotland and a biomedical scientist. She has an interest in adventure medicine, which was ignited through the KCL Wilderness Medicine Society during her undergraduate degree. She loves combining medicine with travel and adventure! Viv likes to explore the Scottish outdoors, ski, surf and climb. She has also volunteered across several African countries including Zambia, Zimbabwe, Uganda and most recently Madagascar.
Wilderness and Expedition Medicine
In this quarter, we will be exploring both ends of the spectrum of temperature illness. We will take you from a case series looking at rescue techniques in hypothermic hill walkers, to sweaty Sicilian runners and the physiological stresses experienced by a healthy volunteer exercising in a heat wave. Sticking with the temperature theme, we will be presenting the 2024 update to evidence-based guidance on the management of cold injury. In fact, it’s been a summer for new evidence based guidelines, which means we will also be presenting the updated WMS guidelines on acute altitude illness. To finish off, we will investigate the effect of alcohol and smoking on the incidence of Acute Mountain Sickness on Mount Fuji.
The Outcome of Walking Cold Patients with Potential Mild Hypothermia to Safety: A Mountain Rescue Case Series
Greene M, Dodds N, Gordon L et al. Wilderness and Environmental Medicine. 14 June 2024.
Laboratory experiments into hypothermia have previously suggested that mobilising patients with even mild hypothermia could potentially be dangerous due to the risk of afterdrop and cardiac arrhythmias. However, these experiments have often utilised immersion cooling in well rested volunteers, which doesn’t quite match up to the slowly cooled, exhausted walkers that find themselves requiring rescue in the British hills. It is thought that a delay in extraction in these people may lead to greater exposure time and more cooling. Greene et al. collected data on all rescues where casualties were exhibiting signs of hypothermia (as defined by the Swiss staging system for accidental hypothermia) and compared the outcomes of those that were walked out immediately versus those that received an element of warming or delayed extraction. Data was collected from various Mountain Rescue teams and the authors admit that there were differences in the completeness of the data and that the core temperatures of the casualties involved may have been different. Despite this, the patients included all displayed clinical features of hypothermia and were in an environment where this was possible. This case series showed no difference in the outcome of patients that were mobilised immediately or received delayed transfer and whilst further study is needed, it provides an interesting perspective on the practicalities of rescue in this scenario.
Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Frostbite: 2024 Update
McIntosh S, Freer L, Grissom C et al. Wilderness & Environmental Medicine. April 5 2024
The Wilderness Medicine Society has reconvened its panel of experts for a number of evidence reviews and updates this summer and we will present you with two of them in this edition of the Evidence Explorer. The first drops the mercury level into frostbite territory and addresses the prevention, diagnosis and management of cold injury. This guideline represents an update on the 2019 edition and is accompanied by strength of recommendation and evidence base for the points put forward. It is comprehensive and a summary that does it justice would not be possible in this piece. Instead, we will simply outline its scope and depth for those of you who’d like to dip your toes into the freezing waters before taking the plunge!
The review covers the pathophysiology of the stages of freezing injury and their classification in the early stages. Formal classification can be difficult in the field and the authors have therefore recommended a two-tier field classification system which can be completed after rewarming but without need for imaging. Preventing frostbite is clearly better than trying to treat it.The various methods for prevention and their effectiveness are discussed in the next section of the review with the options for treatment depending on whether the frozen part has the potential to refreeze or not. Naturally, the early treatment options expand once a person has reached a hospital or high level field clinic. This review covers the management of hypothermia, hydration, rewarming and blisters as well as the use of low molecular weight dextran, aloe vera, antibiotics, tetanus, ibuprofen, thrombolysis, iloprost, heparin and other vasodilators in this setting. Post-thaw therapies are outlined in the final section of the review.
The need for further research into peri-thawing procedures and post-thaw therapies to improve outcome is identified in the review. Overall, it provides a thorough evaluation of the current treatment options available today and is well worth a read to those with an interest in taking people to cold places.
A case report on the physiological responses to extreme heat during Sicily’s July 2023 heatwave
Filingeri D, Valenza A, Ficarra S et al. Physiological Reports. 7 June 2024
You’ll be pleased to hear that things are starting to warm up a bit in this case study, which looks at the physiological response to heat in a healthy volunteer during the July 2023 heatwave in Sicily, where temperatures reached highs of 47 degrees celsius. The reports aimed to look at the effects of physical work or exercise when environmental factors such as solar radiation and airflow are taken into account; all difficult to replicate in laboratory experiments into heat tolerance. The participant was tested on two separate days, one with the highest level of heat warning possible issued by the Sicilian authorities and another where no warnings were in place. As you would expect, they found that exercise in the hotter temperature caused greater physiological stress. However, even on the cooler day, with no health warning, the volunteer still experienced a significant level of physiological stress. Filingeri et al. argue that the current advice regarding heat warnings may underestimate the thermal stress placed on even healthy people during exercise. Whilst this is a case study and represents data from a single participant, it provides good food for thought when planning a trip to warmer climates and considering the effects of rising world temperatures on sporting events.
Summary of Wilderness Medical Society Practice Guidelines for the Prevention, Diagnosis and Treatment of Acute Altitude Illness: 2024 Update
Rodway G, and Luks A. Wilderness Medicine Magazine. 8 July 2024.
We’re heading back to the updated WMS guidelines for this next article with a review of acute altitude illness. Once again the available evidence has been analysed and is presented by a panel of experts to help with prevention, diagnosis and management of Acute Mountain Sickness (AMS), High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE). Naturally there is a fair amount to work through here but the review is divided into clear sections looking at the different presentations. AMS and HACE are discussed together in the first half of the review due to the latter representing a rather extreme progression of the former. HAPE, and concurrent HAPE and HACE are covered in the later sections of the review. The treatment of these conditions depends on the severity of symptoms and whilst it is acknowledged that gradual ascent or even descent are usually the best options, the merits and indications for the various pharmacological approaches are also discussed in detail. This is once again a thorough and detailed review of altitude illness and a highly recommended read for any medic accompanying an expedition in the mountains.
Influence of Smoking and Alcohol Habits on Symptoms of Acute Mountain Sickness on Mount Fuji: A Questionnaire Survey-Based Pilot Study
Horiuchi M, Mitsui S & Uno T. High Altitude Medicine & Biology. 14 June 2024
The possible effects of different comorbidities on an expedition group is something that any medic needs to consider when planning a trip. However, Horiuchi et al make it clear that an individual’s recreational behaviour should also be taken into consideration. This paper looked at how smoking and alcohol consumption affect the incidence of AMS in hikers climbing Mount Fuji. The climbers were given questionnaires to collect data on smoking and alcohol use as well as general demographic data. Results from 887 hikers were analysed.
Symptoms of AMS were present in 45% of participants surveyed. Younger climbers (aged 20-29) were statistically significantly more likely to develop AMS. All ages of climbers were more likely to develop AMS if they had also been smoking during the ascent. The effects of alcohol consumption varied depending on age group. Younger climbers were no more likely to develop AMS with alcohol consumption (though they are already at increased risk in their own right). Middle-aged (50-59) climbers’ risk of AMS did increase with alcohol consumption.
Whilst the results of this study relies on self-reported behaviours, which leaves it vulnerable to bias, it does provide a useful insight into the possible effects behaviour and habits can have on the incidence of AMS within a group.
Global Health and Humanitarian Medicine
This section discusses two neglected tropical diseases, Rift Valley Fever and onchocerciasis. We investigate trends in opiod consumption across Africa and delve into the human factors behind mosquito net adherence. Finally, we explore the relationship between internet use and frailty.
Widening geographic range of Rift Valley fever disease clusters associated with climate change in East Africa
Situma S, Nyakarahuka L, Omondi E, et al. BMJ Global Health. June 2024
Rift Valley Fever (RVF) virus can cause haemorrhagic syndrome, jaundice and encephalitis. It is transmitted by mosquitoes and is found in humid areas. As this climatological profile is met by much of East Africa, the study focused on Kenya, Uganda and Tanzania to assess the relation of weather and RVF prevalence in humans and livestock. Previous studies established that extreme weather which enhances humidity (e.g. flooding) increases vector populations and can trigger epidemics in these regions. There is growing concern that climate change in East Africa will lead to an expanded geographic disease range. This study evaluated 100 disease events from 2008 to 2022. It found that 35% of identified RVF clusters were reported in areas that previously had no RVF history. The results of the study suggest that the combination of increasing temperature, increasing rainfall trends and a decrease in the annual number of dry days is a driving factor behind the escalating public health risk of RVF disease in Uganda. Similar patterns were observed in Kenya. A limitation is that many clusters represent as few as 1-3 human cases, drawing grand conclusions from a small sample size. In addition, the relationship between weather and prevalence is correlative and needs further research to establish if it is truly causal. Finally, due to lack of healthcare infrastructure, it is also necessary to acknowledge that case-reporting may not always reflect true prevalence, and that perhaps by comparing past to current datasets, the study is simply reporting an increase in monitoring.
Elimination of transmission of onchocerciasis (river blindness) with long-term ivermectin mass drug administration with or without vector control in sub-Saharan Africa: a systematic review and meta-analysis
Mutono, N., Basáñez*, M.G., James, A., et al. The Lancet Global Health. May 2024
Onchocerciasis or ‘River blindness’ persists in many countries despite half a century of programmes to decrease disease burden. More than 99% of onchocerciasis cases are found in sub-Saharan Africa. WHO has set an elimination goal by 2030. This systematic review collated data published on sub-Saharan Africa, in which a decade or more of ivermectin mass drug administration had been established (with or without vector control). Of 1525 articles screened after the removal of duplicates, 75 provided 282 records from 238 distinct foci in 19 (70%) of the 27 onchocerciasis-endemic countries in sub-Saharan Africa. It aimed to identify factors which contribute to successful elimination of transmission. The factors contributing to ongoing transmission included lack of vector elimination and holoendemicity. This suggests that long-term larviciding of blackfly-species breeding sites can significantly affect transmission of onchocerciasis. Furthermore, the areas in which continuous treatment with effective therapeutic coverage was established in 80% or more of the eligible population, improved the likelihood of achieving the elimination. Perhaps unsurprisingly, the results of the study indicate that drug administration and blackfly vector control are key.
A proportion of these findings based on self-reported cases, the accuracy of which is difficult to ascertain. Additionally, due to the inclusion criteria, grey literature sources were not included (instead focussing on peer-reviewed articles), which is thought to explain the lack of data on eight onchocerciasis-endemic countries in sub-Saharan Africa. Nevertheless, the results are useful in providing guidance for the implementation of effective measures and can provide data for future transmission modelling studies on onchocerciasis.
Analysis of opioid analgesics consumption in Africa: a longitudinal study from a 20-year continental perspective
Hadjiat, Y., Toufiq, J., Ntizimira, C., et al. The Lancet Global Health. July 2024
Opioid analgesics have been listed as an essential medicine for palliative care and pain relief by the WHO. However, only 8% of available opiates are consumed by those in low/middle-income countries, compared with the remaining 92% being consumed by the high-income countries (who make up 17% of the world’s population). Several factors may contribute to this, though opioid expense underlies many of them. Healthcare professionals across many African countries seem reluctant to prescribe opioids (perhaps also due to cost), favouring non-steroidal anti-inflammatories (NSAIDs), even in cases where opioids would be indicated as first-line treatment. Individuals, aside from cost, may also reject opioids due to the stigma of pain endurance, palliative care and fear. Although cancer incidence and mortality in Africa has consistently risen during the last 20 years, the consumption of opioids remains almost unchanged.
The worldwide use of opioids has doubled each decade, mainly driven by high-income countries. This paper is the first to evidence the low and stagnant use of opioids in African countries between 1999 and 2021, and although it struggles to distinguish between the indications for opioid use, the increase of cancer and mortality strongly imply an increased need for opioids. Quality of data appears to be the study’s most significant drawback. For example, as tramadol is not under international control, it is not reported by the International Narcotics Control Board (INCB), meaning that no conclusions regarding this opioid could be made, and was therefore excluded. In addition, there is uncertainty in the consumption estimates due to imprecise population estimates and the number of stockpiled or unused opioid medications. Nonetheless, given the data and resources this research group did possess, it produced a compelling paper which suggests underconsumption of opioids in many African countries.
Reasons for mosquito net non-use in malaria-endemic countries: A review of qualitative research published between 2011 and 2021
Ladu, H.I., Shuaibu, U., and Pulford, J. Tropical Medicine and International Health. July 2024
Mosquito nets are the recommended method of vector control, yet they are not always used as advised and access to insecticide-treated nets is lacking. In this review, the lack of use of all forms of mosquito nets was analysed, using the qualitative data collated from literature between 2011 and 2021. It seems that the most common reasons for the non-use of mosquito nets were: lack of comfort (from heat and/or sharing one net between whole families), as well as perception of low mosquito levels. Furthermore, insecticide-treated mosquito nets were also underused due to the perception that malaria-risk was low or, conversely, that they needed to be saved for future use. However, the study only included English language publications and focused mainly on rural populations. When evaluating a qualitative study, it is important to remember that the quotes included are also subject to translation and potential bias. Nonetheless, this is an in-depth and analytical review presenting an insight into the under-use of mosquito nets and is unique for its focus on qualitative data, allowing greater insight into human drivers behind non-adherence. This research can guide future interventions to improve mosquito-net use.
Internet use and frailty in middle-aged and older adults: findings from developed and developing countries
Li, L. Globalisation and Health. July 2024
The term ‘frailty’ encompasses the decline in multiple physiological functions of the body, often leading to complicated care plans and burden on healthcare systems. In this unique multi-cohort study, Li investigated the longitudinal correlation between internet use and frailty across 32 countries. These cohorts encompassed a range of digitalisation, with the rates of internet use starting from 5.56% in China to 83.46% in Denmark. The results demonstrated that a country’s degree of development is also reflected in their rates of internet usage, but perhaps unexpectedly, also showed an inverse correlation between internet usage and frailty in middle aged and older adults. I say unexpectedly, as in younger generations, increased internet usage is often an indicator of poorer health (associated with lack of physical activity for example), yet there are many factors that can attempt to explain why in middle-aged/older adults this has the opposite effect in terms of frailty.
The finding that internet use correlated negatively with frailty is up for interpretation and further investigation. Li suggests that internet use mitigates social isolation (which accelerates frailty) and is a convenient source of information on healthy eating, exercise and medical information, which is what this demographic of adults tended to search. The correlation itself is robust, with the extensive sample size and data from 32 countries. Nonetheless, it is difficult to avoid some recall biases in this study, as the data was largely gathered from self-reports. Additionally, some datasets had presented internet use as a household rather than individual, meaning that the higher internet use of younger generations in the household may have skewed the outcome. Finally, this paper does not delve into whether increased internet use amongst the older demographic is in fact, preventing risk of falls or hospitalisation (which also define frailty), due to inactivity. It does however acknowledge the potential limitations and perhaps even negative implications of internet use and urges these to be taken into consideration in future research. Overall, the paper does provide a unique insight into the new and developing relationship between middle-aged/older adults and the internet era, furthering questions about how the two may work together to increase quality of life for this demographic.
