Chapter 27 MILITARY MEDICAL OPERATIONS IN MOUNTAIN

Medical Aspects of Harsh Environments, Volume 2

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Chapter 27

MILITARY MEDICAL OPERATIONS INMOUNTAIN ENVIRONMENTS

PAUL B. ROCK, DO, PHD*; AND EUGENE J. IWANYK, MD†

INTRODUCTION

ESTIMATING DISEASE AND NONBATTLE INJURY AND PERFORMANCEDECREMENTS

Disease and Nonbattle InjuryPerformance Decrements

HEALTH MAINTENANCEPrevention of Environmental Injury and IllnessTreatment of Environmental Injury and Illness

DEPLOYMENT OF MEDICAL SUPPORT ASSETS Environmental Effects on Medical SupportGeneral Principles for Deployment of Medical Assets

SUMMARY

*Colonel, Medical Corps, US Army (Ret); Associate Professor of Medicine, Center for Aerospace and Hyperbaric Medicine, Oklahoma StateUniversity Center for the Health Sciences, Tulsa, Oklahoma 74132; formerly, US Army Research Institute of Environmental Medicine, Natick,Massachusetts 01760

†Lieutenant Colonel, Medical Corps, US Army (Ret); Ellis Eye and Laser Medical Center, El Cerrito, California 94530

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Military Medical Operations in Mountain Environments

INTRODUCTION

• providing a health maintenance program to(a) prevent environmental medical prob-lems and (b) treat them effectively whenthey occur; and

• managing the field medical support assetsto allow efficient treatment and return toduty or evacuation of casualties.

In this general formulation, the mission is appli-cable to most organizational levels of medical sup-port to most tactical units.

The information presented here is organizedaround the simple formulation of the health servicesupport mission stated above. The first section ofthis chapter reviews the potential impact of moun-tain environments on military units and counter-measures that can be recommended to lessen envi-ronmental effects. The next section discusses healthmaintenance in units deployed to high altitude. Thefinal section deals with the effect of the mountainenvironment on the medical support system itself.The considerations underlying the concepts pre-sented are based on providing support to “tradi-tional” ground combat units such as infantry, lightinfantry, armor, and cavalry units. Although manyof the general concepts are relevant to other typesof military units, including special operations units,the unique aspects of medical support of specialoperations are discussed in Chapter 37, MedicalSupport of Special Operations, and Chapter 38, Or-ganizational, Psychological, and Training Aspectsof Special Operations Forces of this textbook.

One of the fundamental challenges faced by medi-cal personnel supporting military units deployed inmountain regions is to deal with the effects of the en-vironment on the health service support mission.Mountain environments have an impact on virtuallyall aspects of the mission. On one hand, mountainsadd to the spectrum of disease and injury that nor-mally occurs during military operations. Indeed, inthe absence of combat, environmental injuries are thebiggest source of casualties that reduce unit fightingstrength. On the other hand, they affect the healthservice support system itself, constraining the optionsfor prevention or treatment of casualties. Factors inthe mountain environment degrade the performanceof medical personnel and equipment and limit theways in which medical assets can be deployed. If theeffects of mountain environments are not anticipatedand successfully avoided or abated, the health sup-port mission, and with it possibly the tactical mission,will be jeopardized.

The purpose of this chapter is to provide infor-mation that will help medical personnel success-fully manage the impact of mountain environmentson the health service support mission. In its sim-plest form, that mission is to conserve the fightingstrength of the tactical unit by

• advising the unit commander about the po-tential impact of the environment on unitpersonnel and operations, and recommend-ing means, countermeasures, or both tolessen that impact;

ESTIMATING DISEASE AND NONBATTLE INJURY AND PERFORMANCE DECREMENTS

Military leaders need good estimates to plan ef-fectively for their unit’s mission. Combat leadersneed estimates of the unit’s fighting strength (man-power) and performance capabilities in the envi-ronment in which the unit will operate. In themountains, they need estimates of the extent towhich the mountain environment itself will degradeunit strength (ie, disease and nonbattle injury[DNBI]) and performance over time. Medical sup-port personnel need estimates of the number of ca-sualties so that they can plan for the care of thosecasualties. In the mountains, they need estimatesof the effects of the mountain environment on man-power and performance to accurately brief the com-bat commander, guide health maintenance activi-ties, and allocate the medical support resources.

Useful estimates of the effects of mountain envi-

ronments on unit strength and performance ideallywould be based on experience, in the same way asthe most useful estimates of battle casualty ratesare derived from “experience tables” based on datafrom previous battles. Unfortunately, there are fewuseful data about medical problems available fromthe mountain warfare experience. For instance, al-though Houston’s excellent review of the effects ofthe environment on past military campaigns in themountain regions of Europe and Asia (Chapter 20,Selected Military Operations in Mountain Environ-ments: Some Medical Aspects) graphically illus-trates the deleterious impact that mountains canhave (eg, what commander today would want tosuffer the nearly 50% reduction in force thatHannibal experienced while crossing the Alps),much of that historical information is not particu-


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larly applicable to current military operations, ow-ing to differences in equipment, transportation, andmedical technology. Similarly, the information oncombat injuries from previous battles with swordsand shields is not especially applicable to thepresent-day battlefield, with its high-velocity bal-listic weapons. Of the conflicts that took place inthe mountains during the 20th century and, there-fore, might be more applicable, the only readilyavailable data on environmental casualties are fromthe Sino–Indian border conflict (1962–1963).1 Ad-ditionally, some data are also available from stud-ies of military training activities in the mountains,2–5

but the information is based on limited numbers ofindividuals.

Even in the absence of extensive experience-based data, medical personnel can make reasonableestimates of the effects of mountain environmentson unit strength and performance by combining somegeneral concepts with extrapolations of the limiteddata available. Estimates are, after all, estimates.Considerations for making reasonable estimates ofDNBI and performance decrements for mountainterrain are presented below.

Disease and Nonbattle Injury

The major components of DNBI in high mountainterrain are listed in Exhibit 27-1 and extensively dis-cussed in Chapters 24, 25, and 26, which deal withacute mountain sickness (AMS), high-altitude cere-bral edema (HACE), high-altitude pulmonary edema(HAPE), and other edematous and nonedematousillnesses. They include conditions that are causedby the hypobaric hypoxia that is characteristic ofhigh-altitude and conditions related to other environ-mental factors. That both hypoxia and other envi-ronmental factors play a role during military opera-tions in the mountains was strikingly demonstratedduring a training exercise at 3,600 to 4,000 m alti-tude in the Colorado mountains.3 The number ofsoldiers evacuated during 5 days of mountain op-erations was more than 10-fold that for the sameunit doing the same maneuvers for the sameamount of time in North Carolina. The casualtiesat altitude were caused by AMS and HAPE, bothrelated to hypobaric hypoxia; traumatic and over-use injuries, related to the rugged topography; andone fatality and five injuries from a lightning strike.

A reasonable method to estimate DNBI for mili-tary operations in mountains is to start with estimatesfor a nonmountainous region, add hypoxia-relatedconditions, and then make appropriate adjustmentsfor other factors that change in the mountains but

are not necessarily related to hypoxia (eg, increasedchance of lightning injury, decreased chance ofmosquito-borne diseases). Experience tables forDNBI are available for the United States6 and mostother military forces. Estimates of DNBI for tem-perate climate operations are a reasonable startingpoint for altitudes from 1,500 to 4,000 m becausethe climate conditions at those elevations are fairlysimilar. Estimates for arctic regions may be a betterbaseline for mountain regions above 4,000 m eleva-tion, where increasingly cold ambient temperaturesprevail.

Considerations for estimating the additional ef-fect of altitude on incidence of hypoxia-related andother environmental injuries are drawn from themilitary and civilian experience in the mountains.Reports from civilian experience are mostly relatedto recreational activity, however. Because tacticalconsiderations dictate the timing, duration, and lo-cation of environmental exposure during militaryoperations, civilian recreational exposure is not

EXHIBIT 27-1

HEALTH THREATS TO MILITARYPERSONNEL FROM MOUNTAINENVIRONMENTS

Hypoxia Related

Acute mountain sickness (AMS)

High-altitude cerebral edema (HACE)

High-altitude pulmonary edema (HAPE)

High-altitude peripheral edema

High-altitude eye problems

Sleep problems with sleep deprivation

Thromboembolism

Exacerbation of preexisting disease

High-altitude pharyngitis/bronchitis

Performance decrements

Not Related to Hypoxia

Trauma

Thermal injury (especially cold injury)

Ultraviolet (UV-A, UV-B) radiation energy

Lightning strikes

Carbon monoxide poisoning

Infections

Hypohydration

Inadequate nutrition

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entirely equivalent.7 Estimates can be made fromthis data, however, by considering activities thatmight be roughly equivalent to military activities.For example, trekking and backpacking in themountains (ie, long journeys on foot carrying camp-ing equipment; see Exhibit 19-1 in Chapter 19,Mountains and Military Medicine: An Overview)are roughly equivalent to an approach march, al-though, owing to tactical contingencies, soldiersoften carry more equipment and set a faster pace.

Altitude illness, which includes AMS, HACE,and HAPE, is the only component of DNBI that isunique to the mountains. As detailed in Chapter 24,Acute Mountain Sickness and High-Altitude CerebralEdema, and Chapter 25, High-Altitude PulmonaryEdema, the incidence of altitude illness is increasedwith increasing severity of altitude exposure, asdetermined by the elevation achieved and the speedof ascent. In general, the altitude at which person-nel sleep is the most important one in determiningthe incidence of altitude illness. Additionally, alti-tude illness decreases over time as individuals ac-climatize. Information presented in Chapters 24 and25 suggests that for ascent rates of 1 to 2 days, theincidence of individuals with AMS symptoms canbe as high as 20% at 2,000 m and 67% at 3,000 m;the incidence of HACE may be 0.1% at 2,000 m andas high as 1.8% at 5,500 m; and the incidence ofHAPE, 0.1% at 2,500 m and 15% at 5,500 m. Manyof those with AMS will not be casualties but will be“medically noneffective” for as long as several days.Dusek and Hansen3 found that 6% of soldiers in aSpecial Forces unit were incapacitated with AMSat 3,600 to 4,000 m, while Pigman and Karakla2 re-ported that 1.4% of Marines were incapacitated at2,000 to 2,600 m. For purposes of estimating unitstrength decrement, all casualties with HACE andHAPE should be considered as needing evacuationfor treatment.

Cases of altitude illness will be clustered in spaceand time. The units that ascend the highest in theleast amount of time will have the most altitude ill-ness, and the prevalence of illness will be greatestduring the first several days to a week or more af-ter ascent. An extremely important point is thatbecause exposure to hypobaric hypoxia is ubiqui-tous at high altitude, all unit members are equallysusceptible to altitude illness, including commandstaff and medical and other support personnel.

Most components of DNBI that are not relatedto hypoxia also vary with altitude. Cold, ultravio-let (UV) -radiation injury, and trauma are commonin many environments other than mountains (in-terested readers should consult Section II: Cold

Environments [Chapters 10–18 and Appendix 1] ofMedical Aspects of Harsh Environments, Volume 18),and the incidence, prevalence, or both in those situ-ations could provide a baseline reference point forestimating altitude rates. UV radiation exposure isincreased with increasing elevation, and conse-quently the estimated rate of injury should be in-creased. The potential for cold injury increases withelevation because ambient temperatures drop, andthe rugged (“nonlinear”) mountain topography willincrease the accidental trauma and overuse injury.The magnitude of increase for these factors is notwell established but it is substantial. Additionally,environmental causality rates will be higher, be-cause of the interaction of factors. Thus, increasinghypobaric hypoxia may contribute to an increasedincidence of cold injury by decreasing plasma vol-ume and impairing cognitive performance andjudgment.

Unlike most components of DNBI, the incidenceof infectious disease in the mountains is more orless inversely related to altitude (ie, the greater thealtitude, the less risk of infectious disease; see Chap-ter 26, Additional Medical Problems in MountainEnvironments). This is largely due to the decreasein arthropod disease vectors and decreased survivalof bacteria in the open environment at altitudesabove approximately 4,500 m. Diseases that arespread by person-to-person transmission, includ-ing fecal–oral transmission of diarrheal diseases,that age-old scourge of military field operations, canoccur at virtually any altitude, however. Conse-quently, rate calculations for the infectious diseasecomponent of DNBI can ignore arthropod vector–related diseases at very high altitudes but shouldretain rate estimates for diseases transmitted person-to-person.

Performance Decrements

Degradation of individual and group military per-formance during high-altitude exposure has beendocumented in controlled studies.3,4,9,10 Most militaryactivity involves behaviors with varying degrees ofphysical exertion and psychological functioning,combined or in rapid serial sequence. The hypobarichypoxia of high altitude impairs both physical andpsychological performance (see Chapter 22, PhysicalPerformance at Varying Terrestrial Altitudes, andChapter 23, Cognitive Performance, Mood, and Neu-rological Status at High Terrestrial Elevation). It is themajor cause of decrements in soldier and unit func-tion, although other factors such as cold exposure andhypohydration also contribute.


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Because the decrease in oxygen content of ambi-ent air is ubiquitous at high altitude, the effects areuniversal and they affect all members of a unit de-ployed to the mountains, including command staffand medical support personnel. Although perfor-mance decrements increase with increasing eleva-tion because the degree of hypoxia increases, theeffects of hypoxia improve over time as the bodyacclimatizes to altitude. Medical officers must appriseunit commanders of both the threat from altitude-related performance decrements, which threatensa unit’s ability to accomplish its mission, and themeans to lessen the impact of those decrements onoperations.

Physical Performance

The main effect on physical performance of hy-pobaric hypoxia at high altitude is decreased maxi-mal aerobic exercise capability and endurance (seeChapter 22, Physical Performance at Varying Ter-restrial Altitudes). Muscular strength and anaero-bic activity are not much affected. Because the en-ergy required to do a specified amount of work (ie,the metabolic cost) does not change with altitudebut the maximum amount of energy that can be ex-pended goes down, individuals have to work at ahigher percentage of their maximal aerobic capa-bility to accomplish any physical task. This meansthat those tasks will either require relatively moreeffort, take longer to complete, or both, comparedwith the same tasks done at lower altitudes. Theamount of decrement in any specific task is a func-tion of the mix of aerobic and anaerobic activityrequired to do the job. Tasks that have a greateranaerobic component are less affected.

The threshold for onset of altitude effects onphysical performance is low, but meaningful effectsdo not begin until altitudes higher than 2,400 m arereached. The rate of decline in maximal exercisecapacity is dramatic above 6,000 m. Importantly,physically fit individuals suffer a greater decrementin their maximal exercise capacity at high altitudethan less fit individuals. They may still be able todo more work than less-fit individuals, however,owing to their higher starting sea-level work capacity.

The effect of physical performance decrementson mission is an interaction of the type of perfor-mance entailed by the task and the contribution ofthe task to the mission. For example, military tasksthat require only a small aerobic energy output atsea level will require an increasing percentage ofthe diminished maximal energy capacity at higheraltitudes, but they can still be accomplished. On the

other hand, tasks that require a large energy out-put may not be possible to perform. If the missiondepends on tasks that do not require a large energyoutput, the altitude-induced performance decre-ment will not create a problem. If it depends onenergy-intensive tasks that cannot be done at highaltitude, then the mission will be in jeopardy.

Exhibit 22-2 in Chapter 22, Physical Performanceat Varying Terrestrial Altitudes, provides specificexamples. For a task that entails prolonged stand-ing on a circulation (traffic) control point (see num-ber 1 in Exhibit 22-2, which pertains to Task #3, MOS95B [Military Police]), the percentage of maximaloxygen uptake increases only from 9% to 13% be-tween sea level and 5,000 m. Consequently it isunlikely that the physical aspects of that task willbe significantly degraded by altitude exposure.However, the energy required to carry tube-launched, optically tracked, wire-guided (TOW)missile system equipment up a 20% grade at a rateof 0.89 m/s exceeds the maximal oxygen uptake at5,000 m and is greater than 95% of the maximaluptake at 4,000 m (see number 32 in Exhibit 22-2;Task #1, MOS 11H [Heavy anti-armor weapons,Infantry]). In theory, the task cannot be accom-plished at 5,000 m. If the mission success dependson standing on a traffic control-point at 5,000 m,there will be little problem. But if mission successdepends on carrying equipment up a slope at 5,000m, then the mission is in jeopardy and alternativemeans to do the task will have to be found.

Once acclimatization has been achieved, maxi-mal exercise capacity improves somewhat with al-titude acclimatization and with physical training athigh altitude, but it never regains sea-level values.It is important that commanders know that maxi-mal performance decrement will always occur athigh altitude, so they can plan for it. Submaximalphysical performance decrements can be negatedby expending more effort, but the cost of doing sois increased fatigue. Chapter 21, Human Adapta-tion to High Terrestrial Altitude, suggests thatsubmaximal physical performance decrements arebest approached by (1) increasing the amount oftime allowed to complete the task, (2) decreasingthe intensity of the work, and/or (3) taking more-frequent rest breaks.

Psychological Performance

High-altitude exposure alters a number of psy-chological parameters, including cognitive and psy-chomotor function, visual parameters, and moodand personality adjustments, in ways that can have

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a negative impact on military performance (seeChapter 23, Cognitive Performance, Mood, andNeurological Status Effects at High Terrestrial Alti-tude). As with physical performance decrements, thepsychological effects are primarily due to hypobarichypoxia and tend to increase with increasing altitudeand improve with acclimatization. Additionally,there is a large individual variability in these effects.

Cognitive function and psychomotor skills areprogressively diminished above 3,000 m and arevery noticeably affected over 5,500 m. In general,cognitive processes are more affected than psycho-motor function. As a result, complex tasks are moreaffected than simple ones, and tasks requiring de-cisions or strategy are more affected than more “au-tomatic” ones. There is some improvement in func-tion with acclimatization, but there is always anelement of intellectual “dulling” at very high alti-tudes. This results in an increased number of er-rors, an increase in the time needed to complete atask, or both.

A common functional strategy for countering theeffects of altitude on task performance is to increasethe time taken to do the job to decrease the numberof errors. Many individuals adopt this strategy ontheir own volition. As a consequence, more time tocomplete most tasks should be anticipated at highaltitude. Increasing proficiency by training beforedeployment and maintaining proficiency while de-ployed at high altitude by frequent practice alsohelp improve performance. Important or critical

tasks always should be carefully checked for errors.The most important sensory decrement from the

standpoint of military performance is a persistentdecrease in night vision that begins as low as 2,500m and does not improve with acclimatization. Thisdiminished night vision will increase the possibil-ity for accidents during night travel and may makeit more difficult to detect enemy movements atnight. Because the decrement is persistent, meth-ods will need to be instituted to lessen its impact(eg, provisions for guidance during night travel,increased reliance on nonvisual means for detect-ing enemy activity at night).

Mood changes and personality-trait adjustmentsthat occur at high altitude can affect the interper-sonal relationships among unit members and dis-rupt unit cohesion. The euphoric response thatmany individuals experience during the first fewhours after ascent can predispose them to accidents.Once the euphoria subsides, a depressed mood, ir-ritability, or apathy can appear. A number of fac-tors in addition to hypoxia, including the person’sunderlying psychological makeup, weather, andsocial bonds will influence mood and personalityadjustments in high mountain environments. Symp-toms of altitude illness can also influence mood,motivation, and performance. Building high moraleand esprit de corps prior to deployment will helplessen the impact of negative mood and personality-trait changes. Prophylaxis to prevent symptoms ofaltitude illness will also help.

HEALTH MAINTENANCE

Medical support activity to sustain the health andperformance of personnel in military units de-ployed to high mountain areas is directed toward(1) prevention of illness and injury and (2) effec-tive detection and treatment of those illnesses andinjuries that occur despite preventive efforts. Effec-tive treatment facilitates rapid return to duty orevacuation of the sick or injured unit member (seeExhibit 27-1 for an array of potential illnesses andinjuries found in mountain environments). Specificinformation on how to prevent, diagnose, and treatthose conditions is presented in the previous chap-ters of the Mountain Environments section of thistextbook and in Medical Aspects of Harsh Environ-ments, Volume 1,8 and Volume 3.11 General consider-ations about ways in which that information canbe used to maintain the health of members of a unitdeployed in mountain terrain are presented here.

Prevention of Environmental Injury and Illness

Prevention of medical problems caused by themountain environment can be accomplished by lim-iting exposure to the mountain environment, byproviding ways to counter its adverse effects, orboth. High altitude is the major factor conferringrisk in the mountains. Increasing altitude not onlyincreases the level of hypoxia and altitude illnessbut also increases risk of cold injury, UV radiationexposure, lightning, trauma, and most other envi-ronment-related conditions. Limiting altitude expo-sure means controlling the elevation, the rate ofascent, or both. This may not always be possiblefor military units deploying into mountainous re-gions because the mission or the tactical situationmay be an overriding priority that dictates unitmovement. In that instance, increased reliance will


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have to be placed on protective measures.Activities by medical personnel to facilitate pre-

vention in a unit deploying to the mountains in-clude (a) recommending countermeasures to theunit commander, (b) providing medical screening,(c) providing training to unit members, and (d) fa-cilitating the provision of necessary equipment andsupplies to unit personnel.

Recommending Countermeasures

General countermeasures for hypoxia-related ill-ness and performance decrements function eitherto promote acclimatization or to protect unacclima-tized individuals against effects of hypoxia. Differ-ent countermeasures have advantages and disad-vantages in specific tactical situations. The unitcommander must choose the best option based onthe mission and tactical constraints.

Options for using altitude acclimatization as acountermeasure are (1) to promote acclimatizationthrough appropriate ascent rates (ie, profiles) or (2)to maintain previously acquired acclimatizationuntil the next ascent (see Chapter 24, Acute Moun-tain Sickness and High-Altitude Cerebral Edema).Two ascent profiles promote acclimatization andprevent altitude illness: (1) slow or gradual ascentand (2) a staged ascent. The recommended profilefor a slow ascent is to sleep 2 or 3 nights at 3,000 mand then spend 2 nights for every 500- to 1,000-mincrease in sleeping altitude thereafter. The recom-mendation for staged ascent is to stop for 3 or moredays to acclimatize at one or more intermediate el-evations before ascending to the final destinationaltitude. As previously noted, the altitude at whichunit members sleep is the most important factor (ie,the lower the sleeping altitude, the better). The dis-advantage of both of these ascent profiles is thatthey take time, which may not be available to a unitin a rapidly evolving tactical situation.

Maintaining previously acquired altitude accli-matization would allow rapid deployment of a unitwithout risking altitude illness. The best way toachieve this from a physiological standpoint wouldbe to station soldiers at high altitude so that theywould always be in an acclimatized state. This strat-egy might be appropriate for a unit with a signifi-cant ongoing altitude mission. The other way tomaintain altitude acclimatization would be to ex-pose unit members to altitude at regular intervals.The schedule for doing that is not known, but couldrequire at least weekly exposures.12 Like stationing

units at high altitude, this strategy might require asignificant ongoing mission to justify the effort andexpense involved.

When means to acquire or maintain altitude ac-climatization are not available, successful rapiddeployment to high mountains depends on phar-macological prophylaxis or supplemental oxygento prevent altitude illness and increase perfor-mance. The logistical problems entailed in provid-ing supplemental oxygen to units much larger thana squad probably prohibit this alternative as a re-alistic option for military deployment. Pharmacologi-cal prophylaxis, on the other hand, is a practical meansfor allowing rapid insertion of unacclimatized mili-tary personnel into high mountain environments.

At present, the most suitable pharmacologicalprophylaxis for military personnel deploying tohigh mountains is acetazolamide (see Chapter 24,Acute Mountain Sickness and High-Altitude Cere-bral Edema). The recommended regimen is 125 to250 mg twice a day or 500 mg slow-release formu-lation once a day, beginning 24 hours before ascentand continuing for several days after reaching alti-tude until soldiers acclimatize. Acetazolamide isboth safe and effective in this prophylactic role. It issanctioned by the US Food and Drug Administration(ie, it is FDA-approved) for prophylaxis against AMS.It also prevents altitude-induced, sleep-disorderedbreathing, which can cause daytime performance dec-rements (see Chapter 26, Additional Medical Problemsin Mountain Environments). In most individuals, ac-etazolamide has only minor, easily tolerable side ef-fects. Prophylaxis with acetazolamide should be usedin individuals with a history of previous altitude ill-ness. Given its effectiveness and relative safety, itshould be strongly considered for all military unitmembers deploying to altitudes where the incidenceof AMS can exceed 25% (ie, > 3,000 m) except for thoseindividuals in whom the drug is explicitly contrain-dicated. There are currently no other recommendedmeans of pharmacological prophylaxis in a militarysetting.

Medical Screening

Medical screening identifies individuals at in-creased risk for medical problems in mountain en-vironments. If the risk to these individuals is high,they can be precluded from deploying. Those withlesser degrees of risk can be deployed with specialprecautions, surveillance to prevent problems, orboth; or they can be identified and treated early

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before becoming casualties. Screening can identifytwo general types of problems: (a) the potential forenvironmental injury and (b) medical conditionsthat could be exacerbated by hypobaric hypoxia.

Environmental Injury. Altitude illness and coldinjury are the main environmental disorders towhich individuals deploying to the mountainsmight have increased susceptibility. Although severalmethods to predict susceptibility to altitude illnesshave been investigated (see Chapter 25, High-Altitude Pulmonary Edema, and Chapter 26, Addi-tional Medical Problems in Mountain Environ-ments), they involve measurements of a person’sventilatory response to hypoxia, and are neithervery sensitive nor practical for use on large num-bers of people. In the setting of a military deploy-ment, a positive history of a previous episode ofaltitude illness may be the most practical predictorof susceptibility. Unfortunately, many individualshave not had sufficient prior exposure to high alti-tude to determine if they are susceptible. For smallunits with a committed high-altitude mission, mea-surement of the cardiac and respiratory responseto normobaric hypoxia (11.5% inspired oxygen) atrest and during 50% of maximum exercise may al-low detection of individuals at high risk of altitudeillness.13

Exacerbation of Preexisting Medical Condi-tions. Preexisting medical conditions that can beexacerbated by altitude exposure are primarilythose that affect respiration and oxygen transport.These conditions are not common in most militarypopulations because they are not compatible withactive service and are either screened out prior toentering the military or at the time the problem de-velops. Conditions that might be found in militarypersonnel and that should be screened for prior todeployment to high altitude are listed in Table 27-1.

Sickle cell trait may be relatively common in mili-tary populations and is thought to confer a risk ofsplenic infarct during exposure to altitudes over2,500 m.14,15 There has been some debate about therisk conferred by sickle trait during altitude expo-sure, owing, in some reported cases,16 to possibleinaccurate identification of the precise hemoglobin-opathy. Because splenic infarct or incapacitation dueto sickling at altitude would be a significant prob-lem for the afflicted individual, the unit, and medi-cal resources, screening for the presence of sicklecell trait by history or laboratory testing should bedone if deployment to high altitude is a possibility.Those identified as having sickle cell trait can thenbe further evaluated on an individual basis to de-termine their specific risk. If they have a mixed he-

moglobinopathy, a high percentage of sickling un-der hypoxic conditions, or both, then the medicalofficer should give strong consideration to givingthose individuals a formal medical profile that lim-its their exposure to altitudes higher than 2,500 m.

Two general options are possible for individualswho are determined by screening to be at high riskfor medical problems during altitude deployment.If the condition for which they are at risk can beprevented by appropriate prophylactic measures,then consideration should be given to allowing thatindividual to deploy with prophylaxis. Examples in-clude use of nifedipine for HAPE or acetazolamidefor severe AMS symptoms. Conditions that do notrespond to prophylaxis should be evaluated for amedical profile to limit altitude exposure.

Individuals with history of life-threateningHAPE or HACE should be evaluated for a medicalprofile to limit their altitude exposure. Likewise,those with a history of thromboembolic event athigh altitude should also be considered for a medicalprofile. Individuals with mixed hemoglobinop-athies or a high percentage of sickling when theirblood is exposed to hypoxic conditions should beconsidered for a profile to limit their exposure.Pregnant women should receive a temporary medi-cal profile to limit their altitude exposure to lowerthan 2,500 m while they are pregnant.

TABLE 27-1

MEDICAL SCREENING FOR DEPLOYMENTTO ALTITUDE

Condition or System Example

History of EnvironmentalInjury

Cardiovascular Disease

Pulmonary Disease

Neurological Disease

Hematological Disease

Musculoskeletal System

Pregnancy

Medications

Altitude illnessCold injury

Essential hypertensionCoronary artery disease

Chronic obstructivepulmonary disease

AsthmaPulmonary hypertension

SeizuresMigraine headache

AnemiaSickle cell trait

Overuse injury

—

Any that cause respiratorydepression


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In units with an altitude mission, initial medicalscreening can be done when an individual joins theunit. Prior to any altitude deployment, medicalrecords for all deploying unit members should bescreened to identify new conditions that may havedeveloped and that could confer risk. All medicalwaivers that allow an individual to stay on activeduty with an otherwise disqualifying medical con-dition should be examined to determine whetherthat condition confers a risk at altitude.

Training

Adequate training is an essential ingredient ofan effective health maintenance program for militarypersonnel deployed to a high mountain environ-ment. Three types of training are needed during thepredeployment period. First, all unit personnelshould be familiarized with the health threats of themountain environment and the countermeasuresfor those threats. Second, the military tasks andskills that might be used during deployment shouldbe trained and practiced to the highest degree ofproficiency, to lessen the impact of altitude-inducedphysical and cognitive performance decrements.Specific strategies to decrease errors and increaseperformance should be briefed (see Chapter 23,Cognitive Performance, Mood, and NeurologicalStatus at High Terrestrial Elevation, and Chapter24, Acute Mountain Sickness and High-Altitude Ce-rebral Edema). Third, physical training should beongoing to maintain a high level of fitness. Withregard to physical training, however, it is impor-tant that unit leaders understand that fitness willnot prevent altitude illness, and that the altitude-induced decrement in maximum physical perfor-mance will be relatively greater in physically well-conditioned individuals (see Chapter 22, Physical Per-formance at Varying Terrestrial Altitudes). Trainingon environmental health threats is the responsibilityof medical support personnel. The military task andphysical training will be provided through the unitcommand structure, but it is the responsibility ofmedical personnel to ensure that the importance ofthat training to the unit capabilities is understood.

Adequate training on health threats in mountainenvironments includes recognition of major envi-ronmental factors and the injury or illness and per-formance decrements they cause, the preventivemeasures that can be taken, and first aid (self careand buddy aid). Environmental factors and thehealth problems they cause are listed in Exhibit 27-1;they are discussed in detail along with the specificcountermeasures in the previous chapters of the

Mountain Environments section of this textbook.In addition to presenting specific environmental

health threats and countermeasures, some key con-cepts should be emphasized. Soldiers should un-derstand that mountains are a complex and inher-ently dangerous environment. They must realizethat hypoxia is ubiquitous, that no one is entirelyimmune to its effects, and that the physical and cog-nitive performance decrements it causes can exac-erbate risks from other environmental factors.Knowing the usual time course of acclimatizationhelps people tolerate symptoms of AMS more eas-ily. If pharmacological prophylaxis with acetazola-mide is required, then soldiers should understandits purpose, safety, and side effects so that they arecomfortable taking the drug.

Factors common to all deployments should alsobe reviewed in training, not only the factors spe-cific to mountain environments. These include per-sonal hygiene, skin care, and maintenance of hy-dration and nutrition. Most of this training shouldtake place prior to deployment. Considerationshould be given to refresher training during deploy-ment, when specific problems noted by medical sur-veillance can be emphasized.

Provisions for Protective Equipment and Supplies

Medical support personnel need to facilitate thesupply and distribution of items necessary forhealth maintenance of unit members during deploy-ment to mountain environments. Clothing and shel-ter suitable for the cold weather conditions are ob-vious requirements. A consideration with clothingsupply is the issue of scarves or balaclavas throughwhich individuals can breathe at very high altitudesto help prevent high-altitude pharyngitis and bron-chitis due to drying of the upper respiratory pas-sages. Adequate sun block for the skin and lips isnecessary, as are UV-blocking sunglasses with sideshields to prevent eye damage from light reflectedoff snowfields and rocks. Sunglasses, gloves, andother items that can be easily misplaced should havecords to attach them to the person so that they areless easily lost when the individual is hypoxic. Hik-ing sticks or staffs will help prevent trauma fromfalls in rugged mountain terrain (Figure 27-1). If pro-phylaxis with acetazolamide is to be used, then ad-equate supplies will have to be obtained and issued.

Provisions for adequate water, nutrition, andfield sanitation are critical elements of health main-tenance in any military deployment—and no lessin deployment to mountain regions; medical per-sonnel should be intimately involved in planning

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for them. As discussed in the chapter by Montainin Medical Aspects of Harsh Environments, Volume 3,11

although the fluid requirement at high altitude isincreased, assuring an adequate supply is fraught withpotential difficulties. Likewise, the caloric requirementis increased in high mountains, but, due to a varietyof factors, the tendency is for decreased food con-sumption. Increasing the carbohydrate content of thediet (to ~70%) will make the rations more palatableand help prevent symptoms of altitude illness.

Poor sanitation, the leading source of noncom-bat disease and manpower losses for military unitsfrom the beginnings of organized warfare throughthe most recent conflicts, is as least as great a prob-lem—if not a greater one—at high altitude as in anyother harsh environment. The combined effects ofcold air temperatures, limited water, and hypoxia-related decrements in cognition and mood constrainboth the opportunity and the motivation for main-taining good personal hygiene. Rugged terrain andlimited water can force personnel to rely on ice andsnow within small, confined areas for both theirwater supply and disposal of waste, creating a highpotential for contamination. In addition, reducedambient air pressure at high altitudes lowers theboiling point of water, making heat sterilization ofwater progressively inefficient at higher altitudes.

Treatment of Environmental Injury and Illness

When preventive measures are unable to pre-clude the occurrence of DNBI, the key to maintain-ing unit fighting strength is either effective treat-ment with return to duty or timely evacuation.Methods for treating of the constellation of DNBIlikely to occur during deployment in mountains(see Exhibit 27-1) are discussed in Chapters 24, 25,and 26. The medical support elements needed toprovide adequate treatment include (a) a surveil-lance system to detect illness and injury as early aspossible, (b) trained medical personnel to providethe treatment, (c) appropriate equipment and sup-plies, and (d) treatment and evacuation facilities.Surveillance, training, and equipment and supplyneeds are discussed here; treatment and evacuationfacilities are discussed below in the Deployment ofMedical Support Assets section of this chapter.

Medical Surveillance

Medical surveillance is an important tool formedical personnel to use at all echelons of the fieldmedical support system. It serves a dual purposein that it facilitates early detection of illness andinjury and also helps identify developing healththreats so that preventive action can be taken. Ef-fective surveillance can be accomplished by (a) ac-tively monitoring parameters of health in unit mem-bers and (b) recording the incidence of injury andillness to facilitate identification of developingproblems so that preventive measures can be taken.

To actively monitor a unit deployed in the moun-tains, medical personnel must see the unit mem-bers frequently enough to have some basis for judg-ing their state of health. The signs and symptomsof environmental illness are indicators to whichmedical personnel obviously should be highly at-tuned. For instance, the absence of an altitude-induced diuresis in the first day or so following as-cent should alert the medical officer to the possibledevelopment of serious altitude illness. Likewise,truncal ataxia is a sensitive sign of developing alti-tude illness. One of the simplest indications of over-all health status of individuals at high altitudes isbody weight. Weight gain or failure to lose a smallamount of weight in the first few days of deploy-ment may signal onset of altitude illness, for it isan indicator that the altitude-induced diuresis nec-essary for successful acclimatization has not oc-curred. Over a longer period of time, body weightreflects nutrition and hydration status. Obtainingaccurate body weights in the field may not be prac-

Fig. 27-1. Special equipment may help decrease environ-mental injuries in mountain environments. Hiking staffs(sticks) can help prevent falls when military personnelmove through rugged mountain terrain. Medical person-nel should recommend procurement and issue of itemsthat could prevent injury, even if these items are not avail-able in the normal military supply chain. Much usefulmountaineering equipment for recreational mountaineer-ing is available in the civilian marketplace. Photograph:Reproduced from Medical Problems of Military Operationsin Mountainous Terrain. US Army Training Film TF8-4915;197–.


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tical or necessary, however. Most individuals arecapable of detecting meaningful weight change inthemselves, so that it may be sufficient for medicalpersonnel to merely inquire about weight changerather than actually measure it. Severe weight lossat very high altitudes (climber’s cachexia; see Fig-ure 26-7 in Chapter 26, Additional Medical Prob-lems in Mountain Environments) will be apparentfrom physical appearance. Hydration status canalso be monitored fairly simply by noting the colorof the urine (as described in Section I: Hot Environ-ments, and Section II: Cold Environments, in Medi-cal Aspects of Harsh Environments, Volume 1.8)

Awareness of the incidence of environmental in-jury and illness is best achieved by keeping writtenrecords and reviewing them regularly to look forincreasing incidence, clusters of events, or specifictypes of illness or injury that indicate a developingthreat (ie, sentinel events). This activity is appro-priate at all echelons of medical support in moun-tain environments.

Training

Because the unique constellation of medical prob-lems and the rugged topography associated withmountain terrain present special challenges to pro-viding medical support for military units deployedin the mountains, medical personnel require extratraining to function successfully. The trainingshould (a) furnish the information necessary to di-agnose and treat the injuries and illness associatedwith high mountain environments and (b) teach thespecific techniques and skills needed to operatespecialized equipment and perform rescue andevacuation from rugged terrain features.

The specific injuries and illnesses that medicalpersonnel are likely to have to treat during deploy-ment to mountain regions are listed earlier in thischapter (see Exhibit 27-1). The techniques for diag-nosis and treatment of these are presented in Chap-ters 24, 25, and 26 of this textbook and are also foundin other sources.7,17–19 In addition to the informationon diagnosis and treatment, the key concept, thathypobaric hypoxia has a pervasive influence in all activ-ity at high altitude, must be stressed. Medical per-sonnel should know that the first step in treatingany altitude-related illness is to either evacuate thevictim to a lower elevation or provide supplemen-tal oxygen. Additionally, medical officers shouldconsider the potential for a harmful interaction ofhypoxia with any medications they administer. Andfinally, they need to realize the extent to which hy-pobaric hypoxia can degrade their own physical

and mental performance and take appropriate stepsto limit the consequences of those effects.

Techniques for evacuation of casualties duringmilitary operations in mountain terrain are foundin US Army publications20,21 and in myriad civiliansources. Some of the subjects that should be cov-ered are techniques for manual carries and littercarries on steep slopes and cliffs (Figure 27-2). Tri-age and evacuation for a mass casualty situationshould be reviewed in the specific context of ava-lanche and rock slides. In addition to specific tech-

Fig. 27-2. Evacuating casualties and moving medical sup-plies in mountain terrain can involve techniques that re-quire special training to perform with competence andsafety. Training should be accomplished prior to deploy-ment. Refresher training and practice during deploymentwill help make the skills more automatic and less vul-nerable to hypoxia-induced decrements in physical andcognitive performance. Photograph: Courtesy of MurrayHamlet, DVM, Chief, Research Support Division, USArmy Research Institute of Environmental Medicine,Natick, Mass.

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niques, the trainer should emphasize several im-portant concepts about mountain evacuation. Per-sonnel must realistically assess their own capabili-ties in the context of hypoxia-induced performancedecrements and plan accordingly. Because weather,terrain, and operational conditions can vary greatlyin the mountains, personnel involved in evacua-tions should always have alternative plans and beskilled in the use of field expedients. Finally, to pre-vent shock or further trauma, they should make theutmost effort to protect the casualty from the harshenvironmental conditions.

Ideally, training of medical personnel should takeplace prior to deployment. The mountains, how-ever, are the best place to train for mountain opera-tions. Consequently, refresher training or practicesessions should be given during deployment when-ever feasible. Personnel with an ongoing missionto support units that deploy should train in moun-tain environments as frequently as possible.

Provision for Equipment and Supplies

The mountain environment affects medical logis-tical requirements for treatment and evacuation ofpatients in two ways. First, the characteristic typesof medical problems found in the mountains deter-mine the equipment and supplies that will be needed.Second, environmental parameters can alter drugaction and the normal operation of some medicalequipment. Additionally, environmental factorssuch as cold temperature and decreased atmo-spheric pressure can have direct detrimental effectson some supplies and equipment (eg, freezing ofliquid medications, volume expansion of air in in-travenous bags or bottles of medication). Planningfor medical support operations in mountain terrainwill have to take these effects into consideration.

The major medical problems caused by the

mountain environment are listed previously (seeExhibit 27-1); deployment planning should providefor sufficient medical supplies to treat the projectedincidence of these problems. Special considerationshould be given to the means for treating altitudeillness because those conditions are not found indeployment to other environments. Supplementaloxygen supplies should be made available when-ever possible and by whatever means, as oxygencan be used in treating all altitude illnesses and itmay be helpful as an adjunctive treatment for othermedical conditions at altitude. “Bottled” oxygen (inmetal tanks) has the disadvantages of being heavy,cumbersome, and possibly explosive if struck bygunfire or shell fragments. In relatively fixed facili-ties with adequate power supplies to run the de-vices, oxygen molecular concentrators are a goodalternative to oxygen tanks.22 In the most forwardechelons, the amount of oxygen a patient breathescan be increased through use of lightweight, por-table, cloth hyperbaric chambers (PHC; eg, theGamow bag), and these devices should be madeavailable. Drugs that should be available for treatingaltitude illness include acetazolamide for treatingAMS and altitude-related sleep disorders, dexam-ethasone for treating severe AMS and HACE, andnifedipine for treating HAPE.

Altitude effects on drug action are primarily afunction of hypoxia-induced changes in body physi-ology. Altitude effects on medical equipment func-tion are largely due to hypobaria. Both effects playa role in general anesthesia for surgery.23,24 The prac-tical limits for useful general anesthesia are notknown precisely, but surgical services should prob-ably not be located higher than 4,000 m, and muchlower would be preferable.25 Ketamine is a reason-able choice for intravenous anesthesia because it hasminimal effects on the airway and the respiratorydrive.25

DEPLOYMENT OF MEDICAL SUPPORT ASSETS

Effective deployment of medical assets is essentialto successful support of military units operating inhigh mountain environments. The assets that areavailable are a function of organization level, but gen-eral principles apply to most levels. The major fac-tors that affect how medical resources are used in themountains are the tactical mission and the environ-ment. In a sense, the tactical mission determines thesupport requirements, while the environment setsconstraints on how those requirements can be met.

Medical assets must be deployed to conform to thetactical plan within the often significant constraintsimposed by the mountain environment.

Environmental Effects on Medical Support

Conformity to the tactical plan is a fundamentalprinciple of medical support. The rugged, nonlineartopography of mountain regions shapes tactical plansin a general way, for it severely limits the ability of


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large units to maneuver. As a result, combat com-manders place increased reliance on smaller, separatemaneuver units that act more independently withinthe overall tactical plan. Medical assets must be con-figured and deployed to support these units.

The mountain environment imposes constraintson virtually all aspects of medical support activi-ties from the ability to establish medical treatmentfacilities with appropriate proximity to the sup-ported units, to establishing and maintaining effec-tive evacuation and resupply. Environmental fac-tors that have the major impact are (a) the ruggedterrain, (b) the decrease in ambient oxygen, and (c)the cold temperature and frequent harsh weather.

Rugged terrain severely limits mobility and linesof communication. The amount of time required foroverland transportation or evacuation of casualtiescan be greatly increased. The routes for movementforward, evacuation, and resupply are often lim-ited by terrain features. Routes that are determinedby features of the terrain are susceptible to disrup-tion by enemy action, or by natural events such asrock slides and avalanches. Vertical terrain also lim-its space for medical facilities.

Low oxygen content in ambient air causes per-formance decrements in medical personnel and alsoin any equipment powered by fuel combustion.Personnel suffer decrements in both physical workand cognitive function. Casualties may needsupplemental oxygen at high altitude for conditionsthat would not require it at lower altitude. Internalcombustion engines on vehicles, generators, andcooking equipment are progressively less efficientat higher altitudes. In addition to low oxygen con-tent, low ambient air pressure may also degradeperformance of equipment. Helicopters and propel-ler-driven aircraft have progressive difficulty op-erating at higher altitudes. The problems are espe-cially significant for takeoffs and landings, whereboth types of aircraft may lack lift, and sufficientrunway space may not be available. Low ambientair pressure may alter the operating characteristicsof medical equipment. Anesthesia and respiratorysupport equipment, for example, are progressivelyinefficient at higher altitudes.

Like low oxygen content, the cold ambient air tem-peratures at high altitude can effect personnel, equip-ment, and many medical supplies. Harsh climate con-ditions affect transportation and may limit options forevacuation and resupply. This means that casualtiesat forward echelons will be held there longer, and thatlarger supply stores are needed there also.

General Principles for Deployment of MedicalAssets

The major constraints to medical support in themountains are (a) the need to support smaller anddisconnected tactical units, (b) the facts that trans-portation may be difficult and mobility limited, and(c) significant performance decrements of person-nel and equipment. The primary means to counterthese constraints are to “fix forward” to maintainproximity to the supported units, to maintain asmuch flexibility as possible in transportation op-tions, and to augment personnel and equipment.

To provide support to smaller and more isolatedmaneuver units, the echelons of the medical sup-port within the combat zone may have to bereconfigured and moved far forward. If the maneu-ver units are widely separated, then forward ech-elons of medical support may need to be augmentedto provide adequate proximity to supported units.Increased reliance may need to be placed on buddyaid training and other multipliers of medical capa-bilities in small, isolated units. These individualswill need to be trained to care for environmentalinjuries prior to deployment. Location of assemblypoints, aid stations, clearing stations, and other el-ements of support at confluences of natural lines ofpatient drift and evacuation routes along creeks,streams, and small rivers may allow coverage ofunits that are dispersed in a wider area, but locatingroutes at these points also increases the opportunityfor disruption by enemy action or by catastrophicenvironmental events such as flooding or avalanches.

The fundamental principle of flexibility is the keyto dealing with transportation problems in moun-tain terrain. Both alternative routes and alternativemethods of transportation must be planned for andmaintained. As previously noted, the rugged topog-raphy of mountains limits the number of naturaltransportation routes for evacuation and resupplyand makes those routes susceptible to disruptionby enemy action or natural catastrophes. To assurecontinued operations, medical personnel shouldidentify and carefully plan for use of all possibleland routes within their area of responsibility.

In addition, all alternative methods of transportshould also be considered and planned for. Airtransportation circumvents many of the problemsinherent in overland travel, but it is severely lim-ited by the landing zone requirements for fixed-wing aircraft and by altitude-ceiling limitations formany military rotary-wing aircraft (ie, helicopters).

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Frequent bad weather conditions in the mountainsalso limit the use of aircraft.

Rugged terrain and the lack of adequate roadsmay severely limit the use of vehicles in manymountain regions. Many areas will not be accessibleby motor vehicles or air transportation. In thoseareas transportation of patients and supplies willhave to be by humans or pack animals (Figure 27-3).Most medical units have contingencies for casualtyand supply transport by litter bearers in the forwardbattle area, but in mountain regions this contin-gency may have to be used to support areas furtherto the rear. Many modern military units have notused pack animals, but their use is an option thatcould be considered in difficult mountain terrain.

In addition to flexibility in routes and in meansof transportation in the mountains, flexibility mustalso be maintained to deal with times when notransportation is possible, owing to weather condi-tions, blocked routes, or both. Medical support

planners must make provisions for the possible ex-tension of normal maximum hold times for casual-ties at all forward echelons of medical support.

Medical support to military operations will requireaugmentation of personnel and provisions for special-ized equipment and training (Figure 27-4). Augmen-tation of personnel in forward elements of medicalsupport will be required because of the necessity tosupport smaller, dispersed combat maneuver units,and because of the decreased reliance on vehicle trans-port and the hypoxia-induced decreased physicalperformance. Decrease in physical performance ca-pacity means an increase to 6-man litter teams (fromthe standard 4-man teams) and shorter distance car-ries. Litter relay points may be needed. Special train-ing for mountain litter-carrying techniques will be nec-essary to function in rugged terrain.

Fig. 27-3. “I calls her Florence Nightingale.” As this BillMauldin cartoon from World War II points out, pack ani-mals are an alternative method of transportation of ca-sualties and supplies in rugged mountain terrain. Copy-right 1944. By Bill Mauldin. Reprinted with permissionby Bill Mauldin.

Fig. 27-4. “That’s our mountain team.” Bill Mauldin’s cartoonfrom World War II uses humor to emphasize the need foraugmentation of personnel in medical units supportingmilitary units operating in mountain terrain. For example,this tall–short team of stretcher bearers could carry a casu-alty up or down a slope and always keep the stretcher level.A more cynical interpretation could be that Mauldin is ridi-culing the Army’s seeming predeliction to view soldiers asinterchangeable parts. Copyright 1944. By Bill Mauldin.Reprinted with permission by Bill Mauldin.


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SUMMARY

jury in the mountains. Appropriate ascent profiles orpharmacological prophylaxis for altitude illness willhelp maintain unit fighting strength. Unit personnelshould be trained to recognize environmental threatsand be provided with appropriate countermeasuresto protect themselves. Medical personnel should betrained to treat the constellation of environmentalmedical problems in the mountains and provisionedwith appropriate equipment and supplies to do so.The mountain environment can severely hamper thefunction of medical support. To conform to the tacti-cal mission and to operate efficiently under the re-strictions imposed by the mountain topography andclimate, medical support units will need to be aug-mented and to maintain flexibility in their configura-tion and deployment.

Medical support in mountain environments re-quires familiarity with the threat and adequateplanning to accomplish the mission. Mountain envi-ronments cause a specific constellation of medicalproblems and performance decrements, in which hy-pobaric hypoxia plays a significant role. To apprisethe tactical commander of possible loss of unitstrength and to plan adequate medical support, medi-cal personnel should estimate the DNBI and environ-mentally induced performance decrements prior todeployment. Health maintenance of military unitsdeployed to high mountain terrain requires preven-tive measures and effective treatment of injury andillness, with return to duty or evacuation of the casu-alty being the two best outcomes. Medical screeningcan identify those at high risk for environmental in-

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Documents

Chapter 27 MILITARY MEDICAL OPERATIONS IN MOUNTAIN