Occupational Aspects of Alpine Helicopter Rescue Operations: Recommendation of the Medical Commission of the Union Internationale des Associations d’Alpinisme

Abstract

Helicopter rescue operations in the mountains or at high altitude are well-known as strenuous tasks often associated with some risk. However, there is no standardized procedure for preventive checkups of rescue personnel by occupational care professionals. Therefore, the Medical Commission of the International Climbing and Mountaineering Federation (UIAA MedCom) suggests the procedure presented in this study. This comprehensive recommendation is based on more than 2 decades of research of MedCom members and extensive literature search. A total of 248 references were selected by the committee as relevant for the topic. To keep the recommendation handy, the complete list is available as supplemental material (see online Supplemental Material). This article recommends standardized procedures for occupational screening and better health of search and rescue personnel.

Introduction

Crews of helicopter rescue services who operate at high altitude must cope with a multitude of concurrent stressors and risk factors, including occasional but extremely high noise levels, cold, heavy workload, environmental factors (eg, harsh weather, rock or icefall, slippery and ice-capped terrain), and many others. The crew must communicate closely and effectively and act promptly when presented with different types of warning signs to perform the rescue operation safely. Pilots conducting a hoist rescue must maintain a stable hover and not exceed their helicopter’s total maximum hoist weight for an external load (ie, generally a maximum total weight of 500 lb [230 kg]). However, the pilot may not know the exact combined weight of the victim, rescuer, hoist, and rescue equipment. This adds another variable to the demanding task of hovering, which requires more power than landing or forward flight, and at altitude, even more power is required to hover, as there is less air pressure for the rotor blades to push against and generate lift.

The personnel operating the physically demanding hoist and/or land rescue require skills and a fitness level that differ significantly from those of the pilot. Paramedics performing simulations of helicopter hoist rescue tasks on land had a peak VO₂ of 41.7±4.5 mL/kg/min and worked at 86%±11% of their VO_{2 peak} for 7.0±3.6 min. ¹ These physiological demands should be considered and assessed when selecting and credentialing staff for deployment.

The standard procedures of aviation medicine for the medical check of the crew members do not differentiate between those for the helicopter pilots and team members who operate the hoist or work in the field. Therefore, the Medical Commission of the International Mountaineering and Climbing Federation (UIAA MedCom) has decided to review the literature and offer a procedure that takes the aforementioned factors into account and offers advice on how to determine if there should be more targeted individual health risk assessments of crew members depending on their function. The differentiation criteria for decision-making may also be used to determine the time when crew members should be reintegrated after a disease.

These recommendations are based on more than 2 decades of the commission’s research and extensive literature search. However, they are not obligatory by law, although they include the mandatory checks and criteria used for assessing helicopter pilots. Helicopter pilots must be checked according to their respective national and international regulations. The procedures presented here are based on the references and studies cited here ^{2 -}9 and are, therefore, not referenced again in these recommendations.

The potential collective addressed by these recommendations is quite large, although not all of them are directly involved in helicopter rescue operations. Küpper ² (2006) provides some data: there are about 10,000 members of the German mountain rescue organizations (including volunteers), and their number in Europe exceeds 30,000. However, since systems differ and regional certifications and statistics also differ, nobody knows exactly how many people worldwide are involved in helicopter rescue operations, but it must be stated that there is a significant number of exposed persons.

The Union Internationale des Associations d’Alpinisme (UIAA) is an international umbrella organization providing specialist, evidence-based recommendations for health and safety issues at altitude, with individual commissions assessing the technical aspects, expedition issues, doping, environmental protection, and others. The medical commission (UIAA MedCom) focuses on the preventive aspects of high-altitude exposure. This includes occupational medicine for people working at high altitude for any reason. In total, the UIAA represents 69 countries worldwide, 37 of which have joined the medical commission (for details, see www.theuiaa.org/organization.html). UIAA MedCom recommendations are a “living project;” whenever new relevant data are available, the respective recommendation will be updated, which normally takes place every 5 to 8 y. The recommendations always focus on the respective topic, aiming to keep them as compressed as possible to keep them handy. Further information may be found in the complete reference list (see online Supplemental Material).

The Initial Screening Process

The first check should be undertaken before a person joins a rescue crew, either for training or for rescue operations. The aim is to evaluate whether the candidate is capable of working as a helicopter emergency crew member (HEMS) in other regions, called search and rescue (SAR) crew members, at altitude or in a mountainous environment within the accepted risk parameters or whether this requires individual advice about health and safety (eg, due to a lack of fitness or the presence of pre-existing diseases). The consequence of the latter may be that the candidate is actually rated as “unfit” and may reapply later when the underlying problem has been solved. This basic check includes the following: 1) the candidate’s history (general and specific for the job), 2) routine checks, and 3) in some cases, specific checks based on the candidate’s history or specific results obtained by routine checks.

The relevant topics that should be focused on when taking the individual’s medical history are given in Table 1. The main difference here is that occupational medicine for rescue teams who are land based does not include or assess the additional specialist health topics concerning altitude and aviation medicine. Procedures in some countries (eg, the United States and Canada) include aspects of aviation medicine but not those of high altitude. A specific problem of the latter topic is the fact that there is still no valid test to predict altitude tolerance, although many attempts have been published.^10,11

Table 1

Candidate’s history

General history	Current symptoms, pre-existing diseases, accidents, surgery, medication, etc, as usual for patients
Specific history (high-altitude and aviation medicine)	Problems during or after flight (which ones?, when?, reproducible?, at which altitude?, how long after arrival at altitude?, and other symptoms?) Problems related to an altitude sojourn, especially shortness of breath at altitude, dyspnea, or reduced fitness (when?, reproducible?, at which altitude?, when after arrival at altitude?, other symptoms?); presence of a history of AMS, HAPE, or HACE? Work history (especially noise exposure or contact with blood)
Immunology	Vaccinations (sufficient or require a booster?) Infectious diseases causing a (life-)long immunity

AMS, acute mountain sickness; HAPE, high-altitude pulmonary edema; HACE, high-altitude cerebral edema.

Special attention should also be paid to noise-induced hearing loss, immunological diseases or diseases (or therapies) that significantly impair the immunological system, circulatory disturbance (hypertension and hypotension with dizziness), cardiac diseases (coronary heart disease/angina pectoris, history of myocardial infarction, arrhythmia, and cardiac insufficiency), cerebral trauma or any neurological or psychiatric disease, diseases or trauma of the middle or inner ear that may impair balance, ophthalmological diseases or trauma that impair visual acuity or depth perception, diabetes mellitus (especially Type I), nephropathy, and dermatological diseases that facilitate the invasion of pathogenic germs or increase sensitivity to UV radiation. The use of drugs or any foods that may have sedative side effects and the use of alcohol or hypnotic drugs are prohibited for SAR crew members when on duty. Of course, any misuse of such substances must have the consequence of being deemed “unfit to fly” immediately. Sensitivity to kinetosis and psychic resilience (acrophobia, overcoming dizziness, and fear of flying) may need specific advice.

The medical check required for such jobs is more comprehensive than that required for most other jobs. Routine investigations that should be included are listed in Table 2. Audiometry or tests for vision are not necessary if the respective data are available from a check performed <6 mo ago. If any pathology is verified, an immediate extended check of the ears is indicated (eg, bone conduction).

Table 2

Medical check with special regard to the kind of search and rescue work

General	Physical examination of the candidate
Laboratory	Urine screening (dipstick) ESR Blood cell count, hemoglobin, erythrocytes, leucocytes, and hematocrit GGT, AST, and ALT Creatinine Serum glucose concentration (where appropriate: oral glucose stress test and HbA1c) Anti-HBc or quantitatively assessed anti-HBs for vaccinated persons Gamma interferon test
Ears	Otoscopy Audiometry (air conduction) at 1–6 kHz
Eyes	Measurement of visual acuity (proximity and distance) Stereoscopic vision Color vision Field of vision Mesopic vision sensitivity to glare
Exercise performance	Spirometry ECG Ergometry
Balance	Romberg test (1 min) Fukuda test (1 min)

ESR, erythrocyte sedimentation rate; GGT, gamma-glutamyl transferase; AST, aspartate transaminase; ALT, alanine transaminase; HbA1c, hemoglobin A1C; anti-HBc, hepatitis B core antibody; anti-HBs, hepatitis B surface antibody.

In some cases with questionable results or pathologies, further specific investigations may be indicated. These include craniocorpography with photo-optical recording, ¹² when the Romberg or Fukuda test provides conspicuous results, or spiroergometry (sometimes with additional lactate concentration analysis), when exercise capacity is abnormal due to unclear reasons. In such cases, the investigator must decide whether the limitation of exercise capacity is caused by the cardiopulmonary system, where the maximum volume of oxygen the body consumes (VO_{2 max)} gives good information, or by peripheral oxygen utilization and muscular training, where lactate levels give valuable information. However, it must be pointed out that lactate concentration is not appropriate to predict altitude tolerance because of the “lactate paradox.” ^{13 -}15 Some prefer physical working capacity at a heart rate of 170 beats/min (PWC170)—a submaximal exercise test that allows the testing of a candidate’s fitness too—widely used in Europe (eg, to check firefighter’s fitness). ^{16 -}18 It may be necessary to perform a 24-h electrocardiography, (stress) echocardiography, or 24-h blood pressure assessment, but a thorax x-ray is indicated only in some rare cases.

Assessment Criteria for “Fitness as an Alpine SAR Crew Member”

Permanently Unable to Work in Alpine Helicopter Rescue Operations

Some medical diagnoses may cause an unacceptable risk for the respective candidate, crew, or patient. After a comprehensive review of the literature, UIAA MedCom defined the diagnoses listed in Table 3, which exclude the respective persons permanently from helicopter rescue operations for safety reasons.

Table 3

Exclusion criteria (“unfit to fly”)

Neurological, otological, or psychiatric symptoms or diagnoses	Impaired consciousness or seizure disorder independent of the cause Neurological diseases (central or peripheral) with significant functional impairment, especially after cerebral trauma, impairment of the cerebral perfusion, organic diseases of the brain or spinal cord, and peripheral neuropathies independent of the cause Disturbance of equilibrium with: ○ Lateral oscillations in the Fukuda stepping test of >20 cm or lateral deviance in the Romberg test of >80° to the right or >70° to the left side, or ○ Longitudinal oscillations in the Romberg test of >12 cm or lateral oscillations of >10 cm, if these did not disappear after the observation periods Chronic attacks of dizziness with significant vestibulo-ocular or retino-ocular disturbance of movement (to be determined by electronystagmography) Any psychiatric disease, also if in the case of a significant amelioration, relapse, or decompensation, may have a significant influence on occupational safety (especially diseases that may impair stress management or assessment of risk)
Drugs	Permanent use of drugs having possible sedative side effects Any kind of drug or stimulant abuse, also if in the candidate’s recent history. When flying, the blood alcohol concentration must be 0.00 ‰.
Ears	An individually increased risk for hearing loss by noise (eg, significant hearing loss in bone conduction of at least 1 ear and at least 1 test frequency of 1–6 kHz) Any vestibular dizziness or auditory vertigo (“Menière’s disease”) Any significant diseases of the inner ear in the candidate’s history (eg, acute hearing loss) Hearing loss of the inner ear or by cochlear nerve or after cerebral trauma Otosclerosis operation in the candidate’s history Candidates who do not tolerate ear protection, headsets, or helmets with integrated communication systems because of any disease of the ear canal or auricle (eg, eczema, which is resistant to therapy) Candidates who are unable to perform pressurization of the ear or the sinuses because of a chronic disease
Eyes	Chronic disease of the external parts of the eyes, which may impair vision
Persons who apply to one or several of the following aspects of internal medicine or performance	Any disease of the cardiocirculatory system that causes a permanent impairment of performance or the ability of regulation and in the long run limits the individual performance to a PWC170 of <3.0 W/kg body weight 2 (especially among patients with coronary heart disease, cardiac insufficiency, pulmonary hypertension, or severe arterial hypertension) Any disease of the respiratory system that causes a permanent impairment of performance or the ability of regulation and in the long run limits the individual performance to a PWC170 of <3.0 W/kg body weight 2 (especially among patients with chronic obstructive pulmonary disease, diseases of the pulmonary tissue that cause restrictive breathing disturbance, and any kind of disturbances of gas exchange) Any change in red blood cells that causes a permanent impairment of performance to a PWC170 of <3.0 W/kg body weight 2 (eg, severe chronic anemia independent from its cause); any disease of the red blood cells or anomalies of hemoglobin that may decompensate acutely in hypoxia (eg, sickle cell anemia) Any disease of the skin or the blood vessels that impairs the peripheral perfusion (causing risk for frostbite) or a history of severe frostbite Significant diseases of the kidney or urinary system (eg, renal failure Grade III° or IV° with a glomerular filtration rate of 30–59 mL/min [7]) Rheumatic diseases with the risk of worsening if exposed to cold climate and all severe stages of rheumatic diseases Any metabolic disease that causes a permanent impairment of performance, alertness, co-ordination, or balance (eg, significant diseases of the thyroid gland, parathyroid, and adrenal glands)
	Medically treated diabetes that is not regularly well stabilized, especially if the patient tends to have hypoglycemia Reactions of intolerance to cold exposure (eg, cold agglutinins, cold urticaria, or cold hemoglobinuria) Permanent reduction of muscular strength or flexibility or the loss of any limb if the impairment causes a permanent degree of impairment that the realization of the task cannot be expected Untreated sleep disturbances (sleep apnea) if they cause a significant impairment of alertness or pulmonary hypertension Reduced immunological competence due to the following causes: ○ Therapy with immune suppressive drugs, cytostatic drugs, or ionizing radiation ○ Chronic (therapy-resistant) eczema of the hands, which impairs the protective barrier effect of the skin against infectious agents ○ Chronic skin diseases, which cause an increased sensitivity to UV radiation

PWC170, physical working capacity at a heart rate of 170 beats/min.

Temporary Concerns for Work in Alpine Helicopter Rescue Operations

When a complete or sufficient recovery of the impairment listed in Table 3 can be expected, these candidates are deemed temporarily unfit to join helicopter rescue crews until the recovery is completed or the symptoms are at least ameliorated to a degree that poses no significant health risk on the employee and it can be expected that the rescue operations will be performed safely. If a candidate demonstrates a fitness level of less than 3.0 W/kg body weight (PWC170), ² create a fitness training schedule and repeat the medical check in 6 to 12 mo, depending on the performance and compliance of that person. Other cases of temporary cessation of SAR work at altitude are required for people with anemia (<11.0 g/dL) until a recovery to normal values can be expected or people with temporarily reduced immune defense (eg, during temporary corticoid medication with high doses or severe acute infectious diseases). In most cases, the ability for pressurization of the ears is temporary because they are induced by acute infections of the upper respiratory system.

Candidates with a body mass index of >28 or a body weight of >90 kg should reduce their obesity to fulfill the minimum fitness requirements necessary to work at high altitude. This must be assessed before becoming a SAR crew member. Moreover, the following external factors put limitations on body weight: the maximum external load for a hoist rescue of a typical helicopter type used for high-altitude rescue is around 500 lbs (230 kg), and the combined weight of the rescuer, patient, hoist, and rescue equipment must not exceed the helicopter’s maximum hoist weight limit. In some regions, heavier helicopters are in operation with hoists constructed for heavier loads (eg, Goodrich and Breeze-Eastern, both licensed for 600 lb [272 kg]). Although such large helicopters show significant disadvantages in Alpine terrain, especially in windy conditions, it is possible to allow a higher body weight of rescuers or a higher total weight of patient, rescuer, and equipment. Whenever the maximum load is reached, independent of the causing load (eg, rescuer’s weight, weight of patients with obesity), alternative operational tactics must be used (eg, rope recovery with the rope fixed in the load hook of the helicopter [“Austrian technique”] or taking patient and rescuer separately by 2 hoist operations). When using the latter option, any survey of the patient is impossible; nonetheless, even for normal hoist operations, during which both the rescuer and the patient are removed together, the patient must be medically stabilized as much as possible since any medical assistance during the hoist operation is extremely limited.

Acute eczema of the hands or forearms or large-scale abrasion, burns, or open blisters, which impair the protective barrier effect of the skin against infectious agents, may cause concerns or require pausing of rescue work. Alternatively, the person may use local protection against any contact with infectious agents.

Candidates who exceed the limits of the Romberg and Fukuda tests, as detailed above, are unable to fly. Accordingly, annual rechecks to test for possible recovery are recommended. However, after the fourth year, any amelioration cannot be expected. This causes permanent concern, and the SAR crew member would not be deemed fit to fly.

Candidates with temporary diseases, which make the use of hearing protection, headsets, or helmets with integrated communication devices impossible for a while (eg, in cases of injuries of the external ear and acute disease of the auditory canal or the auricle), may join the crew again as soon as the symptoms ameliorate to a degree that the devices can be used again without problems.

Candidates who temporarily take drugs that may increase sensitivity to UV radiation should consider avoiding work as a SAR crew member for the duration of the therapy—or at least not at high altitude where there is even more UV radiation. Alternatively, they should use sun protection for any part of the skin that may be exposed and apply a minimum of factor 25 sunscreen.

No Concerns if Specific Preconditions Are Realized

Often, additional procedures reduce the individual health risk of crew members with medical preconditions. In such cases, a careful risk estimation should be performed. Some examples are as follows: if immune defenses are less effective, careful consideration should be done and it should be determined whether further activity may be accepted (and specific preventive procedures must be defined, where appropriate). However, a reduced period until the next medical recheck is recommended. In cases of recurrent migraines, the respective person will require specific advice, which may include the drugs to prevent an attack, if appropriate.

No Concerns at All About Working in Alpine Helicopter Rescue Operations

Any other persons not mentioned above may work as SAR crew members in the mountains, provided that there are no prohibitive restrictions or laws (eg, pregnant women and young people).

Rechecks

Rechecks after a certain time are mandatory for state-of-the-art care by occupational and aviation medicine professionals. The intervals between such checks vary. Their length depends on the work and, sometimes, whether this work has been started recently or was done for longer. The UIAA Medical Commission suggests the first recheck to be done before the end of the sixth month after commencing work, with further rechecks conducted before a 12-mo period ends.

In cases of any disease with a duration of >4 wk or any disease that may significantly impair the performance of the cardiopulmonary or the peripheral muscular system, the equilibrium, or coordination, another recheck should be done independently of the interval certified by the last check. A recheck is also recommended if the employee assumes a correlation between his symptoms or disease and the work.

After 6 mo of finishing employment, get a serological check for hepatitis B/C and HIV for people who had direct contact with patients or used medical equipment.

Conclusion

This recommendation aims to standardize the checks by occupational medicine of SAR crew members working in Alpine rescue systems, especially at high altitude. By this, occupational health and care should be increased for these employees or volunteers who suffer from very specific demands and exposures.