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Review Article| Volume 29, ISSUE 2, P266-274, June 2018

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Challenges of Military Health Service Support in Mountain Warfare

Published:March 15, 2018DOI:https://doi.org/10.1016/j.wem.2018.01.006

      Introduction

      History is full of examples of the influence of the mountain environment on warfare. The aim of this article is to identify the main environmental hazards and summarize countermeasures to mitigate the impact of this unique environment.

      Methods

      A selective PubMed and Internet search was conducted. Additionally, we searched bibliographies for useful supplemental literature and included the recommendations of the leading mountain medicine and wilderness medicine societies.

      Results

      A definition of mountain warfare mainly derived from environmental influences on body functions is introduced to help identify the main environmental hazards. Cold, rugged terrain, hypoxic exposure, and often a combination and mutual aggravation of these factors are the most important environmental factors of mountain environment. Underestimating this environmental influence has decreased combat strength and caused thousands of casualties during past conflicts. Some marked differences between military and civilian mountaineering further complicate mission planning and operational sustainability.

      Conclusions

      To overcome the restrictions of mountain environments, proper planning and preparation, including sustained mountain mobility training, in-depth mountain medicine training with a special emphasize on prolonged field care, knowledge of acclimatization strategies, adapted time calculations, mountain-specific equipment, air rescue strategies and makeshift evacuation strategies, and thorough personnel selection, are vital to guarantee the best possible medical support. The specifics of managing risks in mountain environments are also critical for civilian rescue missions and humanitarian aid.

      Keywords

      Introduction

      It is not possible to identify a specific event as the starting point of mountain warfare. However, the challenges of mountain warfare are not a modern phenomenon. As early as 500 BC, Sun Tzu expressed considerable respect for mountainous terrain in relation to war.

      NATO Mountain Warfare Centre of Excellence. General about mountain warfare. In: Blaznik B, ed. Mountain Warfare within NATO-Initial Study. Poljče, Slovenia; 2016:6–9.

      Many famous military leaders such as Alexander the Great, Hannibal, Napoleon, José de San Martín, and Simón Bolívar experienced the hardships of mountainous terrain during their campaigns.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Paton B.C.
      Cold, casualties, and conquests: the effects of cold on warfare.
      Despite sophisticated technology and growing knowledge, mountainous environments still influenced military campaigns in the 20th century—for example, during World War I and the ongoing Indian-Sino-Pakistan border conflicts.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Paton B.C.
      Cold, casualties, and conquests: the effects of cold on warfare.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      Currently, the ongoing war against terrorism has brought mountain warfare once more into the focus of military planning. According to the North Atlantic Treaty Organization, mountainous terrain provides sanctuary for hostile forces, particularly terrorist organizations.
      Task Group HFM-146. Introduction. In: NATO Research and Technology Organisation
      Review of Military Mountain Medicine Technology and Research Barriers.
      The aim of the present review is to help leaders identify the main environmental hazards by introducing a definition of mountain warfare, understand how mountainous environments affect daily life and warfare, and summarize countermeasures to mitigate the impact of mountainous environments.

      Methods

      A selective PubMed and Internet search was conducted using the keywords (individually and in any combination) “military,” “history,” “mountain warfare,” and “high altitude.” Additionally, we searched bibliographies for useful supplemental literature and included the recommendations of the leading mountain medicine and wilderness medicine societies.

      Definition of mountain warfare

      We have developed a definition of mountain warfare, adopted from Pierce, that will assist military leaders in identifying environmentally challenging battle spaces in mountain areas or similar regions (Table 1).

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      Mountain warfare should be regarded as fighting in terrain with elevation differentials of at least 300 m and additional characteristics, such as complex and rugged terrain, low temperatures, or challenging altitude. To emphasize the challenges of the particular terrain, the terminology used should include all characteristic fields (eg, high-altitude, cold-weather, rugged-terrain mountain warfare). Warfare with any elevation differentials but no additional characteristics should be referred to as normal warfare because no special equipment or training is needed, and every soldier should be able to deal with that topography. Naturally, gray zones and transition zones exist.
      Table 1Different types of warfare
      Type of WarfareDefinition
      1Mountain warfareElevation differentials exceeding 300 m in addition to items 2, 3, 4, 5, 6, or 7
      2Rugged-terrain warfareSeverely compartmented or complex terrain, with
      • mean slope angles of 45° and/or
      • difficult terrain (UIAA II
        UIAA II requires the movement of one limb at a time and a proper setting of the movements.51
        or higher)
      3Cold-weather warfare
      • Persistent mean snow depths of approximately 50 cm and/or
      • Persistent ambient air temperatures below 0°C
      4Arctic warfarePersistent ambient windchill factor temperatures below –30°C
      5Moderate-altitude warfareHeights between 1500 m and 2500 m above sea level (normobaric conditions)
      6High-altitude warfareHeights that exceed 2500 m above sea level (hypobaric hypoxia)
      7Extreme-altitude warfareHeights that exceed 5500 m above sea level (extreme hypobaric hypoxia)
      UIAA, Union International des Associations d’Alpinisme (International Climbing and Mountaineering Federation)
      a UIAA II requires the movement of one limb at a time and a proper setting of the movements.

      International Climbing and Mountaineering Federation. UIAA grades for rock climbing. Available at: http://theuiaa.org/mountaineering/uiaa-grades-for-rock-climbing/. Accessed December 14, 2016.

      By comparison, severely compartmented terrain as well as snow and low temperatures do require special equipment and skills. We suggest considering these types as rugged-terrain warfare and cold-weather warfare to clearly emphasize the tactical, behavioral, and logistic challenges.
      Arctic warfare and (high) altitude warfare are 2 extreme variations of environmentally challenging warfare. We define arctic warfare as fighting with constant windchill factor (not air) temperatures of –30°C. In such conditions, there is an increased risk of frostbite in exposed facial skin within 10 to 30 min for most people.
      • Castellani J.W.
      • Young A.J.
      Human physiological responses to cold exposure: Acute responses and acclimatization to prolonged exposure.
      An environment of this kind cannot be compared with a normal winter. Extra training and equipment are essential.
      Above 2500 m, there is a risk of altitude sickness for nonacclimatized individuals.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.
      Above 5500 m, no permanent human habitation is possible.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      However, the effects of hypobaric hypoxia can already be observed in the form of a reduction of maximum aerobic capacity and endurance even at 1500 m.
      • Küpper T.
      Workload and Professional Requirements for Alpine Rescue [Dissertation; in German].
      We have established the categories “moderate-altitude,” “high-altitude,” and “extreme-altitude” warfare to give consideration to the major influence of altitude on warfare.

      Health service support in mountain warfare and lessons from the past

      Much information exists on mountain warfare in general, but publications which cover the health service support requirements are very limited.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      Until World War I specialized mountain warfare units were rare.
      • Buhrmester H.D.
      The origin of mountain units-a search [in German].
      Therefore, no specialized mountain warfare health support units existed. During World War I, the German Empire and Austria-Hungary were still not prepared for mountain warfare from a medical point of view, despite the foundation of mountain warfare units. Also, the Wehrmacht mostly had to improvise when evacuating casualties during mountain warfare, despite intensive progress in technical mountain rescue and the purchase of special medical equipment suitable for mountain operations in the 1930s.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      Many additional casualties occurred due to accidents during the improvised evacuation efforts and the long duration of evacuation.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      However, the lessons of history give us some important characteristics of mountain warfare that are essential for health service support (Table 2). As early as 550 AD, Mogul Mirza Mohammed Haidar complained severely about performance decrements, weakness, dyspnea, and hallucinations to the point of death during his campaign on the Tibetan Plateau.
      • Houston C.S.
      Mountain sickness.
      However, any incidence of losses due to mountainous environments is difficult to estimate.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      Table 2Casualties from mountainous environment in selected mountain warfare campaigns
      CampaignCasualties from environmental factorsMain environmental factors
      Alexander’s crossing of Khawak Pass
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      Up to 50% of fighting forces killedHypoxia, cold, malnutrition, avalanches
      Alexander’s assault of the Sogdian Mountain Citadel
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      10% of assault force killedFalls in difficult terrain
      Hannibal’s crossing of the Alps
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Paton B.C.
      Cold, casualties, and conquests: the effects of cold on warfare.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Approximately 50% of fighting forces killedFalls in snowy terrain, cold, malnutrition
      San de Martín’s crossing of the Andes
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      33% of fighting forces and 50% of pack animals killedCold, hypoxia, difficult terrain
      World War I front line in the Alps
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      Considerably deviating numbers, probably 150 000–180 000 killed, approximately two thirds of casualties due to environmental factorsHygiene, malnutrition, cold avalanches
      Sino-Indian War
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      More casualties from mountain conditions than from enemy action; up to 20% of Indian forces with AMS of which approximately one third diedHypoxia, cold
      Indian-Pakistan War
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      90% of the 2000 dead and 12,000 injured Indian soldiersHypoxia, cold
      Operation Anaconda
      • Peoples G.E.
      • Gerlinger T.
      • Craig R.
      • Burlingame B.
      The 274th Forward Surgical Team experience during Operation Enduring Freedom.
      15% AMS and 25% orthopedic injuries of coalition casualtiesHypoxia, terrain
      Trainings and exercises
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      10-fold higher compared with same training in nonmountainous terrainVarious reasons
      AMS, acute mountain sickness.
      Numbers are ideally based on the experiences of past mountain campaigns.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Alexander the Great lost half of his fighting men while crossing the Khawak Pass due to a combination of hypoxia, cold, hunger, and dehydration, making this campaign one of the costliest in mountain warfare. During his assault on the Sogdian mountain citadel, approximately 10% of his assault force died due to difficult rock terrain.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      Also, Hannibal lost roughly 50% of his men while crossing the Alps.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Paton B.C.
      Cold, casualties, and conquests: the effects of cold on warfare.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      San Martín lost approximately one third of his troops and half of his pack animals during his 3-week crossing of the Andes, and Bolívar also suffered great losses.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      During World War I, more soldiers died of environmental causes and poor hygiene than because of hostile actions.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].
      In addition to the huge losses of men and material, past campaigns are full of examples that illustrate the hardships of mountain warfare. Alexander the Great experienced the importance of adequate nutrition and Hannibal the effect of poor supply lines and casualty handling on strategic decisions.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Delbrück H.
      History of the Art of War. Volume I: Warfare in Antiquity. Book V: The Second Punic War.
      During World War I, World War II, the Korean War, the Indian border conflicts, the Falkland War, and Operation Anaconda, the effects of poor equipment and insufficient resupply repeatedly limited combat strength and caused devastating cold injuries because the effects of mountain environments were simply underestimated.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Müllerschön A.
      Medical equipment and evacuation during mountain warfare in the First and Second World War [in German].

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      • Midla G.S.
      Lessons learned: Operation Anaconda.
      • Thomas J.R.
      • Oakley E.H.N.
      Nonfreezing cold injury.
      To summarize, the most frequent causes of morbidity and mortality were cold, terrain, malnutrition, subacute hypoxic exposure, and most often a combination and mutual aggravation of these factors.
      • Rock P.B.
      Mountains and military medicine: an overview.
      Except for the last 50 years, the effects of altitude hypoxia were probably minimal because of acclimatization during the slow advance of the soldiers, especially during Younghusband’s campaigns in Tibet and during World War I.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      In recent decades, however, ever-increasing mobility has led to rapid deployments to high altitudes by vehicles or helicopters (vertical maneuver), emphasizing one aspect of mountain warfare that is of special importance: acute altitude hypoxia.
      • Tannheimer M.
      Military missions at high altitudes [in German].
      During the Sino-Indian war, mountain sickness was prevalent in up to 20% in some companies, and one third of the casualties are reported to have died.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      India suffered 14,000 casualties, 2000 of whom died in the conflict with Pakistan at the Siachen Glacier; 90% are estimated to have died as a result of altitude and cold.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      During Operation Anaconda the 274th Forward Surgical Team treated 96 coalition forces casualties, of which 15% suffered from acute mountain sickness (AMS) and 25% from orthopedic injuries that were caused by the rugged terrain.
      • Peoples G.E.
      • Gerlinger T.
      • Craig R.
      • Burlingame B.
      The 274th Forward Surgical Team experience during Operation Enduring Freedom.
      As a general rule derived from training exercises, the number of soldiers who need evacuation has to be calculated more than 10-fold for mountain operations compared with the same maneuvers conducted at low altitude.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      However, the most important lesson from the past is that mountain warfare is increasing in frequency.

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      In 2002, 23 of the 27 ongoing armed conflicts in the world were being fought in mountain areas.
      • Rock P.B.
      Mountains and military medicine: an overview.

      Influence of mountains on warfighting

      In addition to terrain, it is commonly agreed that extreme temperatures, wind, ultraviolet radiation, and snow and ice, but also wastelands and especially hypoxia make mountain warfare especially difficult.
      • Rock P.B.
      Mountains and military medicine: an overview.
      These environmental factors influence the 6 warfighting functions: movement and maneuver, fire, sustainment, intelligence, command and control, and force protection (all preventive measures to minimize the vulnerability of personnel, facilities, and equipment to conserve the force’s fighting potential).

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      From a healthcare point of view, movement, logistics, command and control, and force protection are the most significant.
      Movement is restricted by cold, snow, wind, terrain, and human performance decrement due to altitude. This is even more significant with regard to casualty evacuations. Helicopters currently facilitate evacuation; however, due to the high operating altitude, poor landing zones, poor visibility, wind, and hostile anti-aircraft defenses, helicopter use is not guaranteed.

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.
      In addition, due to the scarcity of roads, vehicle evacuations cannot be guaranteed either.
      Mountain environments hinder logistics simply by restricting movement. Therefore, the delivery of supply goods can be challenging. Additionally, the logistical requirements are far above average, and special mountain equipment may be necessary.

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      Furthermore, environmental parameters can alter the operation of (medical) equipment and change maintenance requirements.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Leadership is one of the key factors when conducting operations in a mountainous and cold-weather environment.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      Hydration, nutrition, proper use of cold equipment, and regular buddy checks are key factors for successful health maintenance.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      Close supervision and strong (self-) discipline are required by everyone. This is aggravated by cognitive impairments at high altitudes, which additionally impair leadership ability.
      • Yan X.
      Cognitive impairments at high altitudes and adaptation.
      The most critical function definitely is medical force protection. Mountains can pose a variety of health threats, most of which increase with altitude (Table 3).
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Hypobaric hypoxia is unique to mountain environments and is therefore the most distinctive environmental factor.
      • Rock P.B.
      Mountains and military medicine: an overview.
      In addition, military personnel are more susceptible than civilian mountaineers to impairments caused by hypobaric hypoxia due to the distinctive differences between military and civilian mountaineering (Table 4).
      Table 3Most common health threats in mountain warfare and their underlying causes
      Main underlying factorHealth threat
      Low atmospheric pressure/hypobaric hypoxia
      • Acute mountain sickness
      • High altitude cerebral edema
      • High altitude pulmonary edema
      • Sleep deprivation
      • Performance decrements
      • Cognitive decrements
      Cold, dry airHigh altitude pharyngitis
      • Rugged, steep and exposed topography
      • Rock and ice fall
      • Landslides
      • Avalanches
      • Crevasses
      • Lightning injury
      • Trauma
      • Suspension trauma
      • Wide temperature ranges
      • Wind
      • Freezing cold injury
      • Nonfreezing cold injury
      • Hypothermia
      • Heat injuries
      Ultraviolet radiation
      • Snow blindness
      • Sunburn
      • Sunstroke
      Combination of above factors
      • Constricted hygiene
      • Hypohydration
      • Malnutrition/Hypoglycemia
      Adapted and amended.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.
      Table 4Differences between civilian and military high altitude mountaineering
      ObjectiveCivilianMilitary
      Preparation timeLong preparation timePotentially at short notice
      PreacclimatizationFreedom of movementNo freedom of movement
      AcclimatizationIndividualTeam approach
      Rate of ascentIndividual
      • Team approach
      • Tactical requirements
      • Potential helicopter or car usage (vertical maneuver)
      Time at maximum altitudeShort (summit)Potentially long (mission accomplishment)
      Abortion criteriaOwn choiceMission accomplishment
      Performance required“Easy going” possibleFull combat strength needed
      EquipmentAs lightweight as possibleAdditional military equipment
      HarassmentsNatureNature and hostile forces
      Chain of evacuationEstablished in commercial expeditionsLimited
      Adapted and amended.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      • Tannheimer M.
      Military missions at high altitudes [in German].
      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.

      Military tactics determine military medicine—solutions for an inevitable challenge

      Military commanders decide, on the basis of tactical considerations, where and how military operations are conducted. Therefore, military tactics dictate military medicine and the avoidance of healthcare challenges in military mountain operations by avoiding mountain ranges is not an option. In fact, proper planning and preparation enhance the probability of being able to cope in mountainous environments and of ensuring optimal efficacy of the deployed troops. Several fields of predeployment planning and preparation have to be addressed for mountain warfare (Table 5). Above all, the battle space has to be analyzed according to Table 1, and the main environmental hazards have to be identified.
      Table 5Summary of preventive measures to mitigate the influence of mountainous environment
      Personnel selection
      Mountain mobility training
      Use of acclimatization protocols
      Use of adapted time calculations
      Use of pack animals
      Providing adequate hydration
      Providing carbohydrate rich diet
      Providing special mountain equipment
      Training in treatment of mountain specific diseases
      Training in prolonged field care
      Training in air rescue techniques
      Training in alternative evacuation techniques
      Preventive measures are intensive mountain mobility training, including physical fitness, rope and climbing techniques, and skiing or snow shoe mobility to mitigate the influence of rugged terrain and snow. Only with high levels of motor skills, proprioception, and body demeanor can high injury rates due to complex terrain be reduced.
      • Peoples G.E.
      • Gerlinger T.
      • Craig R.
      • Burlingame B.
      The 274th Forward Surgical Team experience during Operation Enduring Freedom.
      Behavioral training, experience, and substantial self-discipline are necessary to deal with the harshness of low temperatures. According to estimations, 10 or more years are required to become a truly capable mountain soldier.
      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.
      To deal with the challenges of altitude, acclimatization protocols and adapted time calculations are necessary. A mathematical model predicts that the risk of experiencing AMS increases roughly 4.5-fold for every 1000 m increase in altitude, with AMS severity almost doubling every 1000 m.
      • Beidleman B.A.
      • Tighiouart H.
      • Schmid C.H.
      • Fulco C.S.
      • Muza S.R.
      Predictive models of acute mountain sickness after rapid ascent to various altitudes.
      In simpler terms, the incidence of nonacclimatized or poorly acclimatized individuals with severe AMS can be as high as 10% between 2500 and 3000 m with an additional 10% every 500 m.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      Soldiers affected by AMS or high altitude pulmonary edema or high altitude cerebral edema are “medically non-effective.”
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Data from civilian mountaineering show that if individuals are acutely exposed to an altitude of 4560 m, the prevalence of AMS is approximately 60%.
      • Basnyat B.
      • Subedi D.
      • Sleggs J.
      • Lemaster J.
      • Bhasyal G.
      • Aryal B.
      • et al.
      Disoriented and ataxic pilgrims: An epidemiological study of acute mountain sickness and high-altitude cerebral edema at a sacred lake at 4300 m in the Nepal Himalayas.
      • Maggiorini M.
      • Buhler B.
      • Walter M.
      • Oelz O.
      Prevalence of acute mountain sickness in the Swiss Alps.
      • Graham L.E.
      • Basnyat B.
      Cerebral edema in the Himalayas: too high, too fast!.
      • Schneider M.
      • Bernasch D.
      • Weymann J.
      • Holle R.
      • Bartsch P.
      Acute mountain sickness: influence of susceptibility, preexposure, and ascent rate.
      However, the prevalence of AMS depends on several factors, with the most important being (pre-)acclimatization, individual susceptibility, altitude, time at altitude, and high (anaerobic) activity.
      • Beidleman B.A.
      • Tighiouart H.
      • Schmid C.H.
      • Fulco C.S.
      • Muza S.R.
      Predictive models of acute mountain sickness after rapid ascent to various altitudes.
      • Schneider M.
      • Bernasch D.
      • Weymann J.
      • Holle R.
      • Bartsch P.
      Acute mountain sickness: influence of susceptibility, preexposure, and ascent rate.
      Therefore, a reliable prevalence is hard to predict.
      To counteract altitude-related performance deficits, acclimatization strategies are necessary. Civilian recommendations state that above 2500 to 3000 m, sleeping altitude should only be increased by 300 to 500 m per night with a rest day every 3 to 4 days. If larger gains are necessary, an additional rest day is strongly recommended.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.

      Küpper T, Gieseler U, Angelini C, Hillebrandt D, Milledge J. Consensus Statement of the UIAA Medical Commission Vol 2: Emergency Field Management of Acute Mountain Sickness, High Altitude Pulmonary Edema, and High Altitude Cerebral Edema. 3rd ed. Bern, Switzerland: UIAA, 2012.

      Recommendations for military personnel limit the increase of sleeping altitude to 300 m per night from 2400 m onward.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      However, for tactical and logistical reasons, these rules cannot always be observed, and reactions to hypobaric hypoxia are highly individual.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.
      A rule of thumb is that the larger the group and the lower the experience, the more defensive the ascent protocol should be.
      In addition to a graded ascent, another solution to reduce the risk of altitude sickness is preacclimatization. The optimal methods for preacclimatization have not been fully determined yet, but in general the degree of acclimatization is proportional to the altitude attained and the duration of exposure.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.
      • Muza S.R.
      • Beidleman B.A.
      • Fulco C.S.
      Altitude preexposure recommendations for inducing acclimatization.
      Due to the limited data and highly individual reactions to altitude, it is not appropriate to give exact recommendations. A possibility for preacclimatization other than exposure to natural heights is through intermittent hypoxic exposure under hypobaric or normobaric conditions (chambers, tents, or breathing masks), which is practiced extensively by the Indian Armed Forces and increasingly by civilian mountaineers.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      • Tannheimer M.
      Intermittent simulated hypoxia for pre-acclimatization.
      Pharmacologic prophylaxis with acetazolamide and/or dexamethasone may be considered as well, especially if the operation does not allow time for proper preacclimatization (eg, rescue mission, quick reaction force).
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      In addition to triggering high altitude illnesses, hypobaric hypoxia reduces maximal aerobic capacity and endurance. Consequently, the time needed to perform (sustained) physical tasks increases with higher altitude. The percentage increase can be estimated with predictive models to determine the duration of the actual task at altitude compared with sea level.
      • Péronnet F.
      • Thibault G.
      • Cousineau D.L.
      A theoretical analysis of the effect of altitude on running performance.
      • Fulco C.S.
      • Rock P.B.
      • Cymerman A.
      Maximal and submaximal exercise performance at altitude.
      • Beidleman B.A.
      • Fulco C.S.
      • Buller M.J.
      • Andrew S.P.
      • Staab J.E.
      • Muza S.R.
      Quantitative model of sustained physical task duration at varying altitudes.
      However, exact adaptations are difficult to predict due to additional factors, such as fitness level, altitude sickness, terrain, weather, additional clothing, and equipment.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      • Fulco C.S.
      • Cymerman A.
      Physical performance at varying terrestrial altitudes.
      As a rule of thumb, anaerobic and short-duration activities are less affected than aerobic and long-duration activities.
      • Fulco C.S.
      • Rock P.B.
      • Cymerman A.
      Maximal and submaximal exercise performance at altitude.
      Some tasks with high-energy output will no longer be physically possible due to the altitude-induced performance decrement (10–15% reduction per 1000 m altitude, beginning at 1500 m).
      • Küpper T.
      Workload and Professional Requirements for Alpine Rescue [Dissertation; in German].
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Fulco C.S.
      • Rock P.B.
      • Cymerman A.
      Maximal and submaximal exercise performance at altitude.
      • Fulco C.S.
      • Cymerman A.
      Physical performance at varying terrestrial altitudes.
      In general, adapted planning with an increased amount of time allowed to complete a task, reduced pace or intensity of performed tasks, and/or more and longer breaks are essential.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Fulco C.S.
      • Cymerman A.
      Physical performance at varying terrestrial altitudes.
      • Chatterjee T.
      • Bhattacharyya D.
      • Pramanik A.
      • Pal M.
      • Majumdar D.
      • Majumdar D.
      Soldiers’ load carriage performance in high mountains: A physiological study.
      In our opinion, the most pivotal factor for sound leadership in mountain warfare is the military leader’s personal experience with mountain environments, especially altitude, which is essential to estimate their impact on military tactics. However, history shows that many leaders considerably underestimate the difficulties of mountain warfare.
      • Tannheimer M.
      Military missions at high altitudes [in German].
      • Naylor S.
      Not a Good Day to Die: The Untold Story of Operation Anaconda.
      A further important coping strategy to reduce the impact of high altitude is the use of pack animals for transportation of personnel and material. Because physical exertion is thought to contribute to the severity of high-altitude symptoms, a reduction in physical effort is believed to be beneficial.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      Additionally, adequate hydration and a carbohydrate-rich diet (approximately 70% carbohydrate content of the diet) with small but frequent ingestion will make food rations more palatable, keep physical performance at the highest level possible for a given altitude, and may reduce altitude sickness susceptibility.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.

      Headquarters Department of the Army. TB MED 505: Altitude acclimatization and illness management. Washington, DC: 2013.

      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Furthermore, personnel selection can reduce the risk of medical problems in mountain environments. This applies to combatants as well as noncombatants. A positive history of a previous episode of AMS or cold injury and all medical conditions that affect respiration and oxygen transport should be given special consideration.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Several tests exist that support estimation of the individual risk of AMS and/or the degree of acclimatization.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Canouï-Poitrine F.
      • Veerabudun K.
      • Larmignat P.
      • Letournel M.
      • Bastuji-Garin S.
      • Richalet J.P.
      Risk prediction score for severe high altitude illness: A cohort study.
      • Tannheimer M.
      • Albertini N.
      • Ulmer H.V.
      • Thomas A.
      • Engelhardt M.
      • Schmidt R.
      Testing individual risk of acute mountain sickness at greater altitudes.
      • Tannheimer M.
      • Buzzelli M.D.
      • Albertini N.
      • Lechner R.
      • Ulmer H.V.
      • Engelhardt M.
      Improvement in altitude performance test after further acclimatization in pre-acclimatized soldiers.
      However, it must be pointed out that all these tests have so far shown a limited positive predictive value and should therefore be used conservatively. To date, the most valid data with regard to future altitude tolerance is the individual’s altitude history.
      • Bärtsch P.
      • Grunig E.
      • Hohenhaus E.
      • Dehnert C.
      Assessment of high altitude tolerance in healthy individuals.
      Fighting and surviving in mountain terrain requires special equipment.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      For certain operations, mountaineering and ski equipment is indispensable. Procurement from the civilian marketplace should be advocated by medical personnel if the equipment is not available in the normal military supply chain.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Supply and resupply of special medical equipment such as portable hyperbaric chambers; economical inspiration-triggered oxygen systems; oxygen concentrators; medications for typical health problems; and provisions for adequate water, nutrition, and field sanitation are necessary as well.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Of course, briefing and training in the correct application is a prerequisite.
      Current data from high altitude conflicts suggest that high altitude illnesses and cold injuries have a considerable share in preventable deaths as well as disease and nonbattle injuries in mountain operations.
      • Houston C.S.
      Selected military operations in mountain environments: some medical aspects.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      • Peoples G.E.
      • Gerlinger T.
      • Craig R.
      • Burlingame B.
      The 274th Forward Surgical Team experience during Operation Enduring Freedom.
      Therefore, surveillance, assessment, implementation, and monitoring of field strategies for all mountain-specific diseases (Table 3) and hygiene, skincare, and maintenance of hydration and nutrition have to be part of regular medical training for mountain operations.
      • Rodway G.W.
      • Muza S.R.
      Fighting in thin air: operational wilderness medicine in high Asia.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Because most casualties die before reaching a medical treatment facility, and because trained nonmedical personnel have proven to significantly reduce preventable combat deaths, proper training of medical and nonmedical personnel is required.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Kotwal R.S.
      • Montgomery H.R.
      • Kotwal B.M.
      • Champion H.R.
      • Butler FK Jr
      • Mabry R.L.
      • et al.
      Eliminating preventable death on the battlefield.
      • Eastridge B.J.
      • Mabry R.L.
      • Seguin P.
      • Cantrell J.
      • Tops T.
      • Uribe P.
      • et al.
      Death on the battlefield (2001–2011): implications for the future of combat casualty care.
      High altitude diseases and nonfreezing and freezing cold injuries especially have to be addressed, in accordance with the latest guidelines and international recommendations.
      • Luks A.M.
      • McIntosh S.E.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • Schoene R.B.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of acute altitude illness: 2014 update.

      Küpper T, Gieseler U, Angelini C, Hillebrandt D, Milledge J. Consensus Statement of the UIAA Medical Commission Vol 2: Emergency Field Management of Acute Mountain Sickness, High Altitude Pulmonary Edema, and High Altitude Cerebral Edema. 3rd ed. Bern, Switzerland: UIAA, 2012.

      • Zafren K.
      • Giesbrecht G.G.
      • Danzl D.F.
      • Brugger H.
      • Sagalyn E.B.
      • Walpoth B.
      • et al.
      Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia.
      • Paal P.
      • Gordon L.
      • Strapazzon G.
      • Brodmann Maeder M.
      • Brodmann Maeder M.
      • Putzer G.
      • Walpoth B.
      • et al.
      Accidental hypothermia–an update: the content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM).
      • McIntosh S.E.
      • Opacic M.
      • Freer L.
      • Grissom C.K.
      • Auerbach P.S.
      • Rodway G.W.
      • et al.
      Wilderness Medical Society practice guidelines for the prevention and treatment of frostbite: 2014 update.
      • Sachs C.
      • Lehnhardt M.
      • Daigeler A.
      • Goertz O.
      The triaging and treatment of cold-induced injuries.
      • Donegani E.
      • Paal P.
      • Küpper T.
      • Hefti U.
      • Basnyat B.
      • Carceller A.
      • et al.
      Drug use and misuse in the mountains: a UIAA MedCom Consensus Guide for medical professionals.

      Küpper T, Gieseler U, Milledge J. Consensus Statement of the UIAA Medical Commission Vol 3: Portable Hyperbaric Chambers. 3rd ed. Bern, Switzerland: UIAA, 2012.

      Experience from civilian mountain medicine courses shows that a minimum of 2 weeks of intensive training is necessary for medical personnel to achieve basic mountain medicine capability. However, to achieve acceptable mountain mobility, a minimum of 10 weeks of training seems appropriate.
      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.
      Air rescue should be conducted whenever possible because it is generally the fastest and most gentle possibility of extraction. However, to be proficient in mountain air rescue, special training is imperative for ground and air personnel as well, namely identification of landing zones, special flying, and casualty hoisting and extraction techniques. However, air transportation is often limited by weather conditions, tactical considerations, enemy threat, a lack of landing zones, and altitude-ceiling limitations for many helicopters.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      To mitigate the impact of long evacuation times, special emphasis has to be placed on training in prolonged field care. In addition, strategies to improve and speed up evacuations must be developed and trained—for example, technical rope access maneuvers, traditional mountain rescue techniques, ground transportation by pack animals, or simple hand carriage.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      • Truesdell A.G.
      • Wilson R.L.
      Training for medical support of mountain operations.
      Mountain warfare.
      • Tannheimer M.
      Craniocerebral injury during expedition climbing.
      Close cooperation between medical and nonmedical personnel is essential because all ground evacuation techniques require significant time and personnel.
      Finally, history has shown that mountain warfare is conducted in small, rather disconnected units according to the superior tactical plan, because mountain topography limits the ability of large units to maneuver.

      Pierce SW. Mountain and cold weather warfighting: critical capability for the 21st century-a monograph. Kansas, KS; 2008.

      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Medical assets have to be configured to support those small elements.
      • Rock P.B.
      • Iwanyk E.J.
      Military medical operations in mountain environments.
      Additionally, intensive cross-training in all fields mentioned is required to replace losses and guarantee the sustainability of an operation.

      Conclusions

      Mountain environments present numerous challenges for military operations with hypobaric hypoxia, cold and rugged terrain being the most critical factors. Underestimating environmental influence has decreased combat strength and caused thousands of casualties in past conflicts. Medical personnel have to know these limitations and their countermeasures to give competent advice to military leaders and guarantee medical support is at its best while also contributing to operational success. Thorough planning and preparation are necessary years before mountain operations are launched to build up a solid mountain competency. The specifics of managing risks in mountain environments are not critical for military operations alone but also for civilian rescue missions and humanitarian assistance.
      Author Contributions: Study concept and design (RL, MT); acquisition of the data and literature search (RL, MT, TK); analysis of the data (RL, MT, TK); drafting of the manuscript (RL); critical revision of the manuscript (RL, MT, TK); approval of final manuscript (RL, MT, TK).
      Financial/Material Support: None.
      Disclosures: None.

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