Medical Devices Used in Extreme Conditions in Pre-Hospital

Emergency Medicine: Overview of the Issue, Use Case Regarding

Mechanical Ventilation at Altitude and Advice

Carine Malle

1,* a

, Alban De Luca

and Thierry Chevallier

3,4,5 c

Direction of Training, Research and Innovation, French Defence Health Service,

1 Place Alphonse Laveran, 75005 Paris, France

Archeon, 2 Chemin des Aiguillettes, 25000 Besançon, France

Department of Biostatistics, Epidemiology, Public Health and Innovation in Methodology (BESPIM),

CHU Nîmes, Place du Pr. Robert Debré, 30029 Nîmes, France

UMR 1302, Institute Desbrest of Epidemiology and Public Health, INSERM, Univ. Montpellier, Montpellier, France

Tech4Health-FCRIN, France

Keywords: Extreme Conditions, Medical Devices, Aeromedical Evacuation, Mechanical Ventilation.

Abstract: Pre-hospital emergency medicine sometimes involves taking care of patients in environments far different

from the hospital. Cold, heat, humidity, altitude, wind, etc. put human beings and equipment to a severe test.

What are the extreme conditions to which pre-hospital emergency medicine professionals are exposed? What

types of medical devices are particularly concerned? What are the regulations and standards in force? What

are the impacts of exposure to extreme conditions on medical devices? To answer these questions, we rely on

an analysis of the regulatory and normative context, on a scientific literature review and on a case study

involving mechanical ventilation at altitude. Finally, we share some thoughts and advice intended for health

facilities and users, in order to improve practices in terms of selection, use and monitoring of medical devices

exposed to extreme conditions. This document is illustrated with examples concerning the French defence

health service, but our approach can be applied to any entity concerned with pre-hospital emergency medicine.

1 INTRODUCTION

Pre-hospital emergency medicine focuses on caring

for seriously ill or injured patients before they reach

hospital. It calls upon various specialties:

anaesthesiology, traumatology, toxicology,

psychiatry, etc.

The increasing extension of the field of territories

open to tourism and military operations lead medical

personnel, both military and civilian, to intervene in

environments that are qualified as extreme, either

because of the climatic conditions (cold, heat,

humidity, wind, etc.) or because of the characteristics

of the point of care (aircraft, mountain, sea, etc.).

If the effects of extreme environments on human

physiology have been the subject of numerous studies

https://orcid.org/0000-0002-6824-1383

https://orcid.org/0000-0002-0911-7311

https://orcid.org/0000-0002-5110-6273

carine.malle@gmail.com

for decades, this is not the case for their effects on

drugs, and even less so on medical devices (MD).

After having made an inventory of the extreme

conditions and their impact on the MD, we will

illustrate our point with a concrete example regarding

the use of mechanical ventilation at altitude in the

context of aeromedical evacuations. Finally, we will

try to share some thoughts and advice for health care

institutions and users to improve practices in terms of

selection, use and monitoring of MD exposed to

extreme conditions.

The military medical personnel being very

frequently confronted with extreme environments, we

have chosen to illustrate our point with common

military operational situations. However, we hope

that this work will be of benefit to any health care

Malle, C., De Luca, A. and Chevallier, T.

Medical Devices Used in Extreme Conditions in Pre-Hospital Emergency Medicine: Overview of the Issue, Use Case Regarding Mechanical Ventilation at Altitude and Advice.

DOI: 10.5220/0011923100003414

In Proceedings of the 16th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2023) - Volume 1: BIODEVICES, pages 215-221

ISBN: 978-989-758-631-6; ISSN: 2184-4305

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

215

facility or caregiver practicing pre-hospital

emergency medicine.

2 EXTREME CONDITIONS IN

PRE-HOSPITAL EMERGENCY

MEDICINE

Military medical personnel routinely encounter

extreme conditions, in particular in the context of

medical care for soldiers injured in external military

operations.

2.1 Extreme Climatic Conditions

Due to these activities, military medical personnel are

occasionally faced with the practice of medicine in

extreme climatic conditions, such as cold, heat,

humidity or altitude.

In France, sub-zero temperatures are common in

high mountain areas during the winter period. At

altitude, the decrease in atmospheric pressure and the

rarefaction of the air lead to a decrease in air

temperature. The average thermal gradient is about

0.6°C every 100 m. Thus, when going from

Chamonix valley (altitude: 1100 m) to the summit of

Mont-Blanc (altitude: 4807 m), one loses about 20°C.

Heat exposure is a constant in some theatres of

operation, notably in the Sahel, where military

professionals are faced with temperatures

approaching 50°C. In equatorial areas, like French

Guyana, the humidity rate is comprised between 70

and 90% all year long. It should be noted that these

constraints are often combined with each other,

humidity and heat, altitude and cold, and associated

with other constraints (wind, difficult terrain, stress,

etc.).

2.2 External Military Operations

In external military operations, medical care of the

wounded soldiers is organized into four levels:

- Role 1 corresponds to the initial care of the

wounded soldiers directly on the field. Role 1 must be

mobile and responsive. Resuscitation procedures can

be performed, and the health products available are of

primary necessity. Nurses, physicians but also non-

health professionals are involved.

- Role 2 includes mobile surgical units, rapidly

deployable but with limited autonomy. They are

capable of performing resuscitation and emergency

surgical interventions, in particular haemostasis

control.

- Role 3 corresponds to a heavier and more

important surgical unit with reinforced medical,

surgical and diagnostic means. At this level, the

patient may be stabilized.

- Role 4 corresponds to hospitals located in

mainland France. The patient is evacuated when his

condition is critical or requires care that is not

available on site.

Each level is provided with medical supplies,

including specific MD. Role 1 receives mainly

“rustic” MD, i.e., light, compact, solid and easy to

use, such as portable pulse oximeters (class IIb),

tactical tourniquets (class I), bandages (class I or IIa)

or automatic bone injection guns (class IIb). In role 2,

these same MD are added to all surgical equipment

(e.g., stapler; class III). From role 3 onwards,

caregivers have all the MD commonly used in

conventional emergency medicine, such as external

defibrillators (class III) and emergency ventilators

(class IIb). Thus, each MD is associated with one (or

more) level(s) of use, which will condition the

constraints to which the MD must resist and the type

of user.

2.3 Aeromedical Evacuations

A medical evacuation (MEDEVAC) is the transfer of

a patient, carried out on a physician's prescription, in

order to provide continuity of care and treatment. It

can be performed with or without medical

accompaniment. In times of conflict, the transfer of

these patients is strongly influenced by various

factors such as the operational environment, the

climate, the length and quality of the evacuation

routes and the availability of appropriate means of

transport. In this sense, the air route is most often

chosen.

Several types of aircraft can be used depending on

the number of patients to be evacuated and the

distance to be covered, all of which are equipped with

at least one mechanical ventilator. Without adequate

dynamic correction by the ventilator or by the

physician, the decrease in barometric pressure during

the ascent to altitude is accompanied by an increase

in ventilator delivered gas volume. Depending on the

level of cabin pressurization and on the instructions

set for the ventilator (respiratory rate and fraction of

inspired oxygen (FiO

)), tidal volume can be

increased by up to 30%, which exposes the patient to

an increased risk of barotrauma (pneumothorax or

alveolar trauma related to excess intrathoracic

pressure) and ventilator-induced lung injury (VILI;

alveolar trauma related to too much intra-alveolar

volume sometimes responsible for secondary scar

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fibrosis). A practical example of the impact of altitude

on a mechanical ventilator is displayed in section 4.

2.4 What About CE Marking?

EU Regulation 2017/745 (Annex I. General safety

and performance requirements) is not restrictive in

terms of the environmental conditions to be met:

“7.

Devices shall be designed, manufactured and

packaged in such a way that their characteristics and

performance during their intended use are not adversely

affected during transport and storage, for example,

through fluctuations of temperature and humidity, taking

account of the instructions and information provided by

the manufacturer.”

(Chapter I, page 95)

“14.2.

Devices shall be designed and manufactured

in such a way as to remove or reduce as far as possible:

[...] (b) risks connected with reasonably foreseeable

external influences or environmental conditions, such as

magnetic fields, external electrical and electromagnetic

effects, electrostatic discharge, radiation associated with

diagnostic or therapeutic procedures, pressure,

humidity, temperature, variations in pressure and

acceleration or radio signal interferences;”

(Chapter II,

page 99).

Thus, the instructions for use remain the major

source of information regarding “i

nformation that

allows the user and/or patient to be informed of any

warnings, precautions, contra- indications, measures to

be taken and limitations of use regarding the device.”

(Chapter III, page 106), although design may provide

useful feedback to users

3 IMPACTS OF EXTREME

CONDITIONS ON MD USED IN

EMERGENCY MEDICINE

3.1 Literature Review

Kämäräinen et al. (2012) assessed the resistance of

various single-use MD mainly composed of plastic

materials, such as endotracheal tubes, suction

catheters, and infusers, to a 15-minute exposure to a

temperature of -21.5°C. Resistance was assessed via

a manual stress test designed to mimic normal pre-

hospital use. The authors observed a loss of flexibility

that led in some cases to the rupture of tubes and

catheters. A comparative study of several oxygen

concentrators showed that storage for 24 hours at -

35°C significantly impaired the ability of portable

oxygen concentrators to maintain FiO

at set point

(Blakeman et al. 2016).

In the early 1990s, as part of the development of

heliborne medical evacuations in the United States,

Bruckart and colleagues (1993) evaluated 34 MD,

including defibrillators, ventilators, infusion pumps

and vital signs monitoring devices under various

environmental conditions (in accordance with the

environmental tests described in the American

military standard MIL-STD 810D): altitude (15,000

ft, or 4,572 m), heat, cold, humidity and vibrations.

One third of the MD failed at least one environmental

test, with the failure consisting of a “visible” device

failure. A “visible” failure was defined as a MD that

completely stops working, a display screen that goes

out, a battery that discharges, an alarm that sounds

without reason, etc. In the absence of a performance

evaluation of MD, a dysfunction affecting the

measurement by the sensors would probably not be

identified by these tests. The compliance of two thirds

of the devices evaluated with environmental

standards does not guarantee the safety of patients

treated with these devices in extreme conditions.

Since then, more recent studies have compared

various models of the same type of MD at altitude,

either with the aim of determining the most “suitable”

of them, or with the aim of understanding the cause

of malfunction identified in current practice. For

example, in a comparative study of 4 capnographs

exposed to increasing altitude, one device failed as

early as 3650 m and only one device was still

functional at 5470 m (Pattinson et al. 2004). Few

published studies have not stopped at listing failures

but have actually assessed the performance of MD.

For example, in 2019, a comparative study of 5

syringe pumps showed that miniature models, which

are more easily transportable, were less accurate than

standard-sized models in terms of infusion rate

accuracy as early as 1700 m (Blancher et al. 2019).

Regarding transport ventilators, several studies (e.g.,

Rodriguez et al., 2009; Blakeman et al, 2014;

Boussen et al., 2014) have shown a decrease in the

accuracy of volume delivered by some MD at

altitude, even on MD with altitude-compensating

features. Thus, Boussen's team compared 6

ventilators at moderate altitudes (1500 and 2500 m).

If 4 of them proved to be efficient (average relative

error of the delivered tidal volume <10%), they

showed however that the exposure to a moderate

altitude led to an increase of 30% of the tidal volume

(for a FiO

of 100%) on one of the recent models and

whose use at altitude (up to 3500 m approximately)

was not contraindicated by the manufacturer. It

should be noted that some articles do not mention the

use of measurement sensors independent of those of

the MD, which suggests that the results are based on

Medical Devices Used in Extreme Conditions in Pre-Hospital Emergency Medicine: Overview of the Issue, Use Case Regarding

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the data displayed by the MD itself without

verification of their accuracy.

Although these studies present relatively

concerning results, we do not know whether they

have had any real impact on the MD tested (e.g.,

changes to the design or the manual).

3.2 A Vital Risk for Patient

Due to the fragility of electronic components, active

MD seem to be particularly at risk of malfunctioning

under extreme conditions. Whether the failure results

in an obvious malfunction (e.g., complete shutdown,

display failure) or one that is more difficult to detect

(e.g., measurement error), there is a vital risk for the

patient.

The other types of MD are not spared: hardening,

deformation (shrinking or swelling), rupture,

oxidation, corrosion of materials, delamination of

composite materials, condensation, air bubble

formation, loss of seal, etc. (Janno & Degiovanni,

2018; Parent, 2017) are some of the potential

consequences of exposure of any MD to extreme

conditions. Continuous or repeated exposure to

extreme conditions also participates in the accelerated

aging of MD, which requires specific maintenance

procedures. It therefore seems essential that MD

intended to be used in extreme conditions be

evaluated under these conditions during preclinical

testing. Standards have been established to harmonize

practices.

3.3 Main Applicable Standards

Regarding Extreme Environments

and Their Limits

Even if they are not mandatory, standards allow to

meet certain requirements of the applicable

regulations.

These standards are of 2 types: horizontal

standards that concern development and

manufacturing processes, risk analysis, clinical

investigations and quality assurance systems, and

vertical standards that concern specific MD. They are

continually evolving because of the constant

evolution of MD.

If the conformity of MD to these standards is

important to take into account, one must however be

aware of their limits. A first limitation is the existence

of several standards depending on the country and the

context (notably civil/military, air/land). A second

limitation is the relative freedom left to manufacturers

in the choice of tests performed to claim compliance

with these standards. With regard to altitude, for

example, the military standards AECTP-230 and

MIL-STD-810 indicate different exposure levels that

can be investigated, but it is up to the manufacturer to

choose which level to apply to test his MD. Thus, the

manufacturer may claim compliance with a military

aeronautical standard even though the MD has only

been evaluated at moderate altitudes (e.g., 2500 m).

A third limitation lies in the interpretation of test

results. Most of these standards remain superficial as

to the evidence of performance and safety that must

be provided. For example, one can see that the

standard for transport ventilators (ISO/IEC 10651-

3:1997 “Lung ventilators for medical use - Part 3:

Particular requirements for emergency and transport

ventilators”) requires at a minimum that the ventilator

“continue to function” under extreme conditions:

“Extreme conditions [...] Note - The ventilator might

continue to function but outside the specified

tolerances.” (6.8.3.e, page 7).

Table 1: Main applicable standards relative to MD used in

extreme conditions.

Publisher Standard title

Scope of

application

NATO

STANAG 4370

“Environmental

testing”

MD used in

the military

field (in

NATO

countries)

Department of

Defense, USA

MIL-STD-810E

“Environment

engineering

considerations and

laboratory tests”

MD used in

the US

army

Special

Committee

135 (SC-135)

DO-160G

“Environmental

conditions and test

procedures for airborne

equipment”

On-board

MD in

aircraft

International

standard

ISO/IEC 60601-1-

2:2014

Active MD

International

standard

ISO/IEC 60068-2-6

exposed to

vibrations

International

standard

ISO/IEC 60068-2-27

exposed to

shocks

NATO: North Atlantic Treaty Organization

STANAG: Standard Agreement

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4 CASE STUDY: MECHANICAL

VENTILATION IN

AEROMEDICAL EVACUATION

4.1 LTV® 1200

The LTV® 1200 (Care Fusion, San Diego, USA) is

currently present in French MEDEVAC aircrafts. It is

a turbine ventilator that can operate in both controlled

and spontaneous mode with inspiratory support.

The LTV® 1200 ventilator is intended to provide

continuous or intermittent ventilatory support for the

care of persons requiring mechanical ventilation. The

ventilator is a restricted MD intended for use by

qualified and trained personnel under the direction of

a physician. Specifically, the ventilator is applicable

to adult and paediatric patients weighing at least 11

pounds (5 kg). The ventilator is suitable for use in

institutions, at home or in transport.

The temperature must be between +5 and +40°C

and the relative humidity between 15% and 95%. The

device complies with the international standard IEC

68-2-27 for shock resistance, the international

standards IEC 68-2-6 and IEC 68-2-34 for vibration

resistance and the US military standard MIL-STD-

810E for shock resistance in ground and helicopter

transport. The device has also been approved by the

FDA as a “transport ventilator” and the leaflet states

that the LTV® 1200 is “suitable for use in institutional,

home, or transport settings”. However, the

manufacturer does not claim the standard for transport

ventilators (ISO/IEC 10651-3:1997 “Lung ventilators

for medical use - Part 3: Particular requirements for

emergency and transport ventilators”). While the

leaflet refers to the device's ability to automatically

adapt tidal volume in response to increasing altitude,

no indication is given regarding the altitude range at

which the device should be used.

4.2 Performance Evaluation of the

LTV® 1200 at Altitude

In 2012, the French defence health service conducted

a study comparing the performance of 3 ventilators,

including the LTV® 1200, at simulated altitude in a

hypobaric chamber. The performance of the

ventilators on an artificial lung was measured at

ground level (FL0), at 2400 m (FL80) and at 3600 m

(FL120).

This study showed that the tidal volume (V

)

delivered by the LTV® 1200 at FL80 and FL120 was

significantly increased compared to the ground

measurement. Whatever the altitude, the Vt delivered

never respected the V

set point (450 or 700 ml). If

the measurements were within the ± 20% margin

provided by the ISO/IEC 10651-3 standard at FL0

and FL80, this was no longer the case at FL120. For

a set point of 450 ml (breathing rate = 12 breaths per

minute; FiO

= 50%), the ventilator delivered an

average of 540 ml at FL120 (figure 1A). Furthermore,

when the FiO

set point was increased from 50 to

100%, the V

was even higher, increasing to an

average of 585 ml (figure 1B). Similar results were

observed with a tidal volume set point of 700 ml. This

study concluded that the LTV® 1200 did not meet the

stability criteria necessary for a transport ventilator

(Forsans, 2012). However, the LTV® 1200 does still

equip airborne MEDEVAC today. This study

illustrates the unsuitability of certain medical MD for

the environment in which they are used. As patient

safety is at stake, we would like to share some

thoughts and advice for health facilities and users.

Figure 1: LTV® 1200 performance at altitude.

A and B parts display two different sets of instructions

(framed text). BPM: breaths per minute; FiO

: fraction of

inspired oxygen; V

: tidal volume.

Medical Devices Used in Extreme Conditions in Pre-Hospital Emergency Medicine: Overview of the Issue, Use Case Regarding

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219

5 CONSIDERATIONS AND

ADVICE FOR HEALTH

FACILITIES AND USERS

Before purchase by the health facility, the analysis of

requirements (by biomedical engineers) should be

based on general recommendations (in particular the

WHO technical series on MD: “Assessment of

medical device requirements”) and specific

recommendations for each type of MD, and should

include all the constraints to which the device is

intended to be exposed. The choice of a MD over

another should be based on reliable, verifiable

information that is the responsibility of the

manufacturer (instructions for use) and not on a sales

pitch.

After purchase by the health facility, in the

absence of specific recommendations from the

manufacturer for the planned use, health facilities

should ensure that the performance and safety of the

device under extreme conditions are evaluated before

use. This may involve different types of tests: pre-

clinical tests, usability evaluations or even clinical

investigations as defined in the EU Regulations

2017/745 and 2017/746. Monitoring should include

traceability of conditions of use and the collection of

safety information related to these (extreme)

conditions of exposure/use. Finally, user training

should include awareness of the impact of extreme

conditions on the device (figure 2).

6 CONCLUSIONS

To conclude, we show that pre-hospital emergency

medicine is inseparable from the notion of “extreme

conditions”, particularly in the French defence health

service. The types of MD concerned are very diverse

and of all classes. Only the instructions for use

provide reliable information about the conditions

supported by a given device. The claim of conformity

to environmental standards must be analysed with

care and is in no way a guarantee of the performance

and/or safety of the MD. The scientific literature on

the impact of extreme conditions on MD is relatively

poor and official recommendations in terms of

exposure to extreme conditions are almost non-

existent. One interpretation of this finding could be

the rarity of malfunctions, but we also suspect an

under-reporting of incidents associated with a strong

publication bias. Finally, the use case we described

illustrates in a masterly way the gap that can exist

between the needs of caregivers and the equipment

they actually have. It also highlights the lack of

communication within a healthcare institution

between the medical personnel who use MD and the

department in charge of selecting and purchasing

them.

Figure 2: Tips for health facilities and users.

This problematic raises ethical questions. How

should the user behave when confronted with the

emergency care of a patient with a medical device in

unexpected extreme conditions? Use the medical

device anyway and risk sanctions? Not to use it at the

risk of letting the patient's condition deteriorate? How

should he report the incident to his hierarchy? In our

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view, in the same way that exceptions to the

collection of patient’s consent in emergency

situations have been established, the unplanned use of

a medical device in the emergency context should be

the subject of reflection so as to result in rules of good

practice ensuring protection of both patients and

users. A major limitation of this article is that we have

not found any tangible evidence (incident reports,

product recalls, clinical investigation results, etc.) to

prove that this problem is a clinical reality. However,

we have collected several testimonies from French

defence health service caregivers who have

encountered difficulties in the use of MD in an

operational context. This paradox raises questions.

Our hypothesis is that incidents related to extreme

conditions are under-reported by users, in particular

because it is considered that the issue is not related to

the device but is the responsibility of the user who has

not followed the instructions for use. It seems crucial

to encourage the reporting of these incidents, without

implicating the manufacturer's responsibility, in order

to measure their frequency and severity in real life.

ACKNOWLEDGEMENTS

We would like to thank the entire teaching staff of the

“Développement d’une nouvelle technologie de

santé: pourquoi, quand et comment réaliser les

études cliniques?” degree for giving me the occasion

to work on this fascinating topic and the Direction of

training, research and innovation of the French

defence health service for their strong support. We

also thank the medical and paramedical staff of the

French defence health service for their relevant

feedback.

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