Contents
- Introduction and Collaborators
- Expedition and Wilderness Medicine Section
- Global Health and Humanitarian Medicine Section
- Want to get involved?
‘April showers bring May flowers…’
This old adage feels appropriate for the wet spring that we’ve experienced this year. After all the rain, the sun is finally shining through and the countryside is bursting with colour. You might see golden gorse, scarlet poppies or violet bluebells. This season, we have gathered together a collection of summaries as striking as a field of wildflowers. We hope you enjoy this edition of the Evidence Explorer.
Abbie Oster is a medical student at the University of Leeds, who has just finished her intercalated year in Physiology at King’s College London. In her free time, she enjoys powerlifting, running and the occasional ski trip. Her dream job is to be a ski doctor in the Alps, once she has perfected her French! She is looking forward to returning to Leeds and the moors to do some hiking.
Soo Jeong Han is a medical student at King’s College London. She is interested in expedition and humanitarian medicine. Reviewing articles for the Evidence Explorer has allowed her to delve into the research side of global health and health inequalities. She enjoys travelling the world and experiencing many different cultures, as she herself has lived in six different countries growing up!
Wilderness and Expedition Medicine
This edition is especially adventurous, with articles linked to every sort of environment. We discuss the energy required for ocean crossings, nutrition at altitude and vital signs monitoring in space. We summarise the effect of delayed suspension syndrome on aerial activities and musculoskeletal injury trends in trail runners.
Maximal Sustainable Energy Intake During Transatlantic Ocean Rowing Is Insufficient For Total Energy Expenditure And Skeletal Muscle Mass Maintenance
Holsgrove-West R, Iniesta R, Abdelrahman D et al. The Physiology Society: Experimental Physiology. February 2024
This article explores the physiological limits of energy intake (EI) during extreme endurance activities, particularly focusing on a transatlantic rowing race. The study involved 49 participants, both male and female, aged 24 to 67, who rowed for approximately 46 days, covering 3000 miles. Researchers measured EI, total energy expenditure (TEE), body mass, and muscle mass before and after the race.
They found no significant differences between sexes or age groups in EI, TEE, or body mass loss. Despite participants consuming EI at about 2.5 times their resting metabolic rate (RMR), it was insufficient to match the total TEE, indicating a physiological limit to EI. The study highlights that even with a maximal sustainable EI, individuals experienced significant body mass loss, suggesting a limit to the body’s ability to intake energy during prolonged ultra-endurance activities. With the increasing popularity of ultra-endurance sports it’s important to consider adequate nutritional intake when supporting the endeavours of those undertaking these feats.
Beyond the realm of sports, this study’s implications are important in crucial areas like managing critical illness, navigating space travel challenges, and addressing ageing-related concerns, underscoring human energy dynamics across diverse scenarios. The article also demonstrates the importance of good nutritional planning for extended expeditions, revealing the challenge of sustaining optimal nutritional equilibrium in such demanding circumstances.
Nutrition In Women At High Altitude: A Scoping Review—UIAA Medical Commission Recommendations
Andjelkovic M, Paal P, Kriemler S et al. High Altitude Medicine & Biology. March 2024
This review article looks at the role of nutrition for women during short-term, high-altitude activities. High-altitude affects the body in many ways and therefore optimising nutrition is vital. The researchers found that high-altitude exposure induces metabolic changes, impacting carbohydrate and fat utilization. While menstrual cycle phases may influence metabolic responses, it was found to be more important to ensure sufficient carbohydrate intake to support overall health and performance. Protein consumption, particularly in relation to muscle anabolism and catabolism, warrants further investigation.
Hydration is important, considering increased respiratory and urinary water losses at altitude. Weight loss patterns differ between sexes, with appetite suppression and increased energy expenditure contributing to this. Iron metabolism is pivotal, as iron deficiency is more common in women and can impact erythropoiesis, which is crucial for acclimatization. However, evidence on iron supplementation remains inconclusive.
Regarding supplementation, few studies address women specifically, highlighting the need for further research. While carbohydrate drinks and beet juice may aid performance and acclimatization, zinc and leucine supplementation show limited benefits. Overall, maintaining energy balance and hydration is key for high-altitude performance, with consideration for individualized nutritional needs and supplementation strategies. The review demonstrates the need for more comprehensive research to elucidate women-specific nutritional requirements in high-altitude environments. It is interesting to know more about nutritional requirements specifically for women, considering the significant influence hormones play over systemic functions in the body. This understanding suggests an opportunity to tailor nutrition to better support women’s health and well-being.
Delayed Suspension Syndrome Onset In Aerially Suspended Victims Through Leg Raising
Willihnganz S, Ahmed Z, Lee J. Wilderness and Environmental Medicine Journal. March 2024
Suspension syndrome (SS) is due to venous blood pooling in the extremities during passive suspension, occurring in activities like mountaineering or industrial work at heights. Venous blood pooling leads to functional hypovolemia, inducing pre-syncopal symptoms and can cause loss of consciousness or death. This study aimed to explore leg raising as a prevention strategy for SS, hypothesizing it could delay symptom onset.
University of Birmingham students participated in the study, randomly assigned to control or intervention groups. Participants were suspended in neutral or legs-raised positions, with measurements collected pre, mid, and post-suspension. Leg-raised participants demonstrated significantly longer suspension times and lower pain ratings, suggesting delayed symptom onset. The study highlighted the potential of leg raising to delay SS symptoms in passively suspended individuals, offering insights for emergency workers. Notably, leg raising reduced lower extremity mottling, an indicator for early SS symptoms. These findings could inform standard operating procedures for aerial rescue, enhancing emergency response protocols and provide better advice for paramedics and pre-hospital medics working in the field.
Further research with larger sample sizes and continuous data collection methodology is needed to ensure the findings of this research is valid. Using advanced techniques like ultrasound or near-infrared spectrometry could provide more information about onset of SS. The simulation nature of this study, small sample size and young participants may affect generalizability. Therefore, future investigations are needed and should explore additional interventions to prevent or delay SS onset.
Musculoskeletal Injuries During Trail Sports: Sex And Age Specific Analyses Over 20 years From A National Injury Database
Owen M, Workman C, Angileri H et al. Wilderness and Environmental Medicine Journal. March 2024
In this study, the incidence of MSK injuries was investigated in relation to the rising popularity of trail sports in the past two decades. From analysis of US emergency department patients (2002-2021 inclusive), there was a significant rise in injuries seen during the period. Interestingly, while males constituted a larger proportion of injuries in the early 2000s, females surpassed them in injury rates from 2010 onward. The increase in female injury rates aligns with the growing participation of females in outdoor activities, underscoring the need to understand and address gender-specific injury patterns. Looking at the differences between age groups, those under 18 exhibited higher rates of head injuries and concussions, indicating a potential area of concern for youth participating in trail sports. On the other hand, individuals over 65 showed higher rates of fractures, emphasizing the importance of tailored interventions to mitigate injury risks in older populations, such as monitoring for reduced bone strength in osteoporosis.
Further analysis revealed distinct injury patterns between sexes, with males more prone to shoulder, upper trunk, and hand injuries, while females experience more elbow, wrist, knee, lower leg, or ankle injuries. Moreover, females were more likely to sustain strains/sprains and fractures, highlighting potential anatomical and physiological differences contributing to injury susceptibility. The study also identifies discrepancies in injury rates compared to expected values for specific activities and age groups. For instance, mountain biking participation among those under 18, had higher injury rates than predicted, signalling a need for targeted interventions such as concussion prevention education and helmet promotion.
Despite limitations in data representation and analysis, the findings underscore the importance of injury prevention strategies in trail sports. This is particularly important to address sex-specific and age-related injury patterns, in order to promote safe and enjoyable outdoor recreational activities.
A Built-In Guidance System To Monitor Vital Signs In Space And On Earth
Huerta R, Kaduk S, Fatai L et al. Aerospace Medicine and Human Performance. March 2024
This article addresses the challenge of providing timely and effective medical support during remote operations and exploration missions, both on Earth and in space. With longer evacuation times and limited access to medical facilities, future deep-space exploration missions require enhanced medical care for crew members. Technological advancements, particularly in telemedicine, have significantly improved medical support from the ground, increasing the crew’s ability to handle medical emergencies independently.
The study compared the use of a ‘Tempus Pro’ (a tool to measure a range of vital signs) in medically trained and medically untrained subjects, comparing the usability and ratings of ease. The results found that both groups were able to obtain stable and valid vital signs within a clinically acceptable time frame. While medically experienced individuals performed faster, the inexperienced group demonstrated significant improvement after one simulation, suggesting the device’s effectiveness in training individuals with limited medical background. This has potential benefits for future space missions.
Despite limitations such as a small sample size and the absence of female subjects, the study demonstrates the potential of automated medical devices equipped with guidance systems to provide lifesaving support during remote missions.
Global Health and Humanitarian Medicine
This section summarises a range of topics including communication about herbal medicine during pregnancy, a potential solution to anti-venom shortages, the long term efficacy of the dengue vaccine and the feasibility of psychological therapy being delivered remotely in a humanitarian setting.
Patient Physician Communication On Herbal Medicine Use During Pregnancy: A Systematic Review And Meta-Analysis
Hyea Bin Im, Jung Hye Hwang, Dain Choi et al. BMJ Global Health March 2024.
This systematic review of 111 studies across 51 countries has revealed that 34% of pregnant women use herbal remedies during pregnancy, believing these to be more natural and mild compared to pharmaceutical medications due to the potential risk of teratogenicity. For example, ginger, peppermint, and chamomile have proven effective in relieving nausea and vomiting, while cranberry consumption has demonstrated efficacy in preventing urinary tract infections. However, only 28% of these women disclosed their use of herbal remedies to their healthcare providers, often due to perceived safety (sometimes from unreliable internet sources) and a lack of inquiry by doctors. This could lead to inappropriate use of remedies, for example, inappropriate use of ginger can lead to stomach irritation, heartburn, and even cardiac arrhythmias. Prolonged use of chamomile has been associated with a higher risk of preterm delivery and low birth weight.
It was found that disclosure about herbal remedy use to healthcare providers resulted in significantly better health outcomes for pregnant women, while non-disclosure was correlated with higher maternal and neonatal mortality rates. This highlighted the importance of more effective communication and proactive inquiry into the use of herbal remedies to improve antenatal care and, in turn, reduce mortality rates in both mother and baby.
African Polyvalent Antivenom Can Maintain Pharmacological Stability And Ability To Neutralise Murine Venom Lethality For Decades Post-expiry: Evidence For Increasing Antivenom Shelf Life To Aid In Alleviating Chronic Shortages
Gabriela Solano, Sinead Cunningham, Rebecca J Edge et al. BMJ Global Health. March 2024.
Antivenom is a polyclonal mixture of antitoxin antibodies refined from hyperimmunised horses or sheep. It is currently the only established treatment for snake envenomation, which is thought to cause approximately 81,000 – 138,000 deaths each year and permanently disables a further 400,000 people worldwide. It would be helpful if the stocks of these antivenoms lasted a long time, but antivenom stocks are known to last only 2-5 years (depending on the antivenom), after which time these are discarded. Even in places where antivenom distribution and storage is limited, substantial quantities of antivenom are still discarded. The most notable example of this is Sub-Saharan Africa, where suboptimal inventory management and lack of research around national antivenom distribution requirements contributes to a waste of up to 50% of stocks despite the extremely limited supply.
This study, using in vitro and murine in vivo methods, provided evidence that the South African Institute for Medical Research (SAIMR) polyvalent antivenom can retain preclinical efficacy and maintain acceptable stability for up to 25 years after its stated expiry date. This provides promising evidence that supports the use of expired antivenoms in emergency scenarios where in-date antivenoms are not available. There is precedent for this, as the US Food and Drug Administration (FDA) approved the use of expired North American coral snake antivenom.
Feasibility And Acceptability Of Phone Delivered Psychological Therapy For Refugee Children And Adolescents In A Humanitarian Setting
Fiona S. McEwen, Hania El Khatib, Kristin Hadfield et al. Conflict and Health Jan 2024
This is the first study to explore feasibility and acceptability of telephone-delivered therapy with refugee children in a humanitarian setting. Accessibility of psychological therapy is a huge barrier for refugee children, not only because of the shortage of mental health professionals, but also the cultural stigma of receiving therapy, especially in conflict zones. This study used telephone delivered therapy (the Common Elements Treatment Approach – CETA) by lay counsellors (n=3) to try to bridge this accessibility gap. The children (n=11) that were contacted lived in informal tented settlements in the Beqaa region of Lebanon. The counsellors, family members and children themselves were interviewed after the session, and the results thematically analysed.
The results showed that telephone-delivered CETA was effective in reducing symptoms for many of the Syrian refugee children. It also showed that various factors (such as the family’s preconceived attitude to mental health) and the relationship with the counsellor and the family affected the efficacy of the therapy delivered. Challenges in logistics, such as poor network coverage and communication difficulties over the phone were also highlighted.
Post Discharge Malaria Chemoprevention In Children Admitted With Severe Anaemia In Malaria Endemic Settings In Africa: A Systematic Review And Individual Patient Data Meta Analysis Of Randomised Controlled Trials
Kamija S Phiri, Carole Khairallah, Titus K Kwambai et al. The Lancet Global Health Jan 2024.
Severe anaemia poses a significant risk of death for young children, especially in malaria-prone regions. Surviving children often face further risks of death or hospital readmission after discharge. Researchers have conducted a comprehensive review and meta-analysis to evaluate the effectiveness of monthly malaria chemoprevention in children recovering from severe anaemia.
Numerous databases were reviewed for relevant studies, ultimately including three double-blind, placebo-controlled trials from The Gambia, Malawi, Uganda, and Kenya. These trials involved 3,663 children and tested different malaria prevention drugs administered monthly post-discharge. Children who received malaria chemoprevention showed a 77% reduction in mortality and a 55% reduction in readmissions during the intervention period compared to those given a placebo. However, the protective effects did not last beyond the treatment period, highlighting the need for continued research into extending these benefits. One major limitation is the small number of trials analysed, which made it difficult to assess heterogeneity and publication bias.
Long Term Efficacy And Safety Of A Tetravalent Dengue Vaccine (TAK-003): 4·5 Year Results From A Phase 3, Randomised, Double Blind, Placebo Controlled Trial
Vianney Tricou et al. The Lancet Global Health Feb 2024
Dengue fever threatens nearly half of the global population, particularly in endemic regions. To address this, researchers evaluated the long-term efficacy and safety of the tetravalent dengue vaccine, TAK-003, in children and adolescents. This is an ongoing RCT across 26 medical centres in 8 dengue-endemic countries.
The vaccine was effective against all four dengue virus serotypes in previously exposed participants, while it showed efficacy against DENV-1 and DENV-2 in those without prior exposure. Of note, it is difficult to predict the transmission dynamics of the different DENV stereotypes. Serious adverse events were similar between the TAK-003 and placebo groups over the 4.5 years, with no deaths attributed to the vaccine. This study highlights TAK-003 as a promising long-term solution for dengue prevention in endemic regions, with further research required to explore its efficacy across different populations and serotypes.
