An underwater explosion (also known as an UNDEX) is a chemical or nuclear
explosion that occurs under the surface of a body of water. While
useful in anti-ship and submarine warfare, underwater bombs are not as
effective against coastal facilities.
Properties of water
Underwater explosions differ from in-air explosions due to the properties of water:
Mass and incompressibility (all explosions) – water has a much higher density than air, which makes water harder to move (higher inertia).
It is also relatively hard to compress (increase density) when under
pressure in a low range (up to about 100 atmospheres). These two
together make water an excellent conductor of shock waves from an explosion.
Effect of neutron exposure on salt water (nuclear explosions only) – most underwater blast scenarios happen in seawater,
not fresh or pure water. The water itself is not much affected by
neutrons but salt is strongly affected. When exposed to neutron
radiation during the microsecond of active detonation of a nuclear pit,
water itself does not typically "activate", or become radioactive. The two elements in water, hydrogen and oxygen, can absorb an extra neutron, becoming deuterium and oxygen-17 respectively, both of which are stable isotopes. Even oxygen-18 is stable. Radioactive atoms can result if a hydrogen atom absorbs two neutrons, an oxygen atom absorbs three neutrons, or oxygen-16 undergoes a high energy neutron (n-p) reaction
to produce a short-lived nitrogen-16. In any typical scenario, the
probability of such multiple captures in significant numbers in the
short time of active nuclear reactions around a bomb is very low. They
are somewhat greater when the water is continuously irradiated, as in
the closed-loop primary cooling system of a nuclear reactor. However, salt in seawater readily absorbs neutrons into both the sodium-23 and chlorine-35 atoms, which change to radioactive isotopes. Sodium-24 has a half-life of about 15 hours, while that of chlorine-36
(which has a lower activation cross-section) is 300,000 years. The
sodium is the most dangerous contaminant after the explosion because it
has a short half-life.
These are generally the main radioactive contaminants in an underwater
blast; others are the usual blend of irradiated minerals, coral, unused nuclear fuel, and bomb case components present in a surface blast nuclear fallout,
carried in suspension or dissolved in the water. Plain distillation or
evaporating water (clouds, humidity, and precipitation) removes
radiation contamination, leaving behind the radioactive salts.
Effects
Effects of an underwater explosion
depend on several things, including distance from the explosion, the
energy of the explosion, the depth of the explosion, and the depth of
the water.
Underwater explosions are categorized by the depth of the explosion. Shallow underwater explosions are those where a crater
formed at the water's surface is large in comparison with the depth of
the explosion. Deep underwater explosions are those where the crater is
small in comparison with the depth of the explosion, or nonexistent.
The overall effect of an underwater explosion depends on depth,
the size and nature of the explosive charge, and the presence,
composition and distance of reflecting surfaces such as the seabed,
surface, thermoclines, etc. This phenomenon has been extensively used in antiship warhead
design since an underwater explosion (particularly one underneath a
hull) can produce greater damage than an above-surface one of the same
explosive size. Initial damage to a target will be caused by the first shockwave; this damage will be amplified by the subsequent physical movement of water and by the repeated secondary shockwaves or bubble pulse. Additionally, charge detonation away from the target can result in damage over a larger hull area.
Underwater nuclear tests close to the surface can disperse
radioactive water and steam over a large area, with severe effects on
marine life, nearby infrastructures and humans. The detonation of nuclear weapons underwater was banned by the 1963 Partial Nuclear Test Ban Treaty and it is also prohibited under the Comprehensive Nuclear-Test-Ban Treaty of 1996.
Shallow underwater explosion
The 1946 Baker test, just after the chimney had broken through the cloud, and the crack had formed on the water's surface
The Baker nuclear test at Bikini Atoll in July 1946 was a shallow underwater explosion, part of Operation Crossroads. A 20 kiloton warhead was detonated in a lagoon
which was approximately 200 ft (61 m) deep. The first effect was
illumination of the sea from the underwater fireball. A rapidly
expanding gas bubble created a shock wave that caused an expanding ring of apparently dark water at the surface, called the slick, followed by an expanding ring of apparently white water, called the crack. A mound of water and spray, called the spray dome,
formed at the water's surface which became more columnar as it rose.
When the rising gas bubble broke the surface, it created a shock wave in
the air as well. Water vapor in the air condensed as a result of Prandtl–Meyer expansion fans
decreasing the air pressure, density, and temperature below the dew
point; making a spherical cloud that marked the location of the shock
wave. Water filling the cavity formed by the bubble caused a hollow
column of water, called the chimney or plume, to rise 6,000 ft (1,800 m) in the air and break through the top of the cloud. A series of ocean surface waves
moved outward from the center. The first wave was about 94 ft (29 m)
high at 1,000 ft (300 m) from the center. Other waves followed, and at
further distances some of these were higher than the first wave. For
example, at 22,000 ft (6,700 m) from the center, the ninth wave was the
highest at 6 ft (1.8 m). Gravity caused the column to fall to the
surface and caused a cloud of mist to move outward rapidly from the base
of the column, called the base surge. The ultimate size of the
base surge was 3.5 mi (5.6 km) in diameter and 1,800 ft (550 m) high.
The base surge rose from the surface and merged with other products of
the explosion, to form clouds which produced moderate to heavy rainfall
for nearly one hour.
An example of a deep underwater explosion is the Wahoo test, which was carried out in 1958 as part of Operation Hardtack I. A 9 kt Mk-7
was detonated at a depth of 500 ft (150 m) in deep water. There was
little evidence of a fireball. The spray dome rose to a height of 900 ft
(270 m). Gas from the bubble broke through the spray dome to form jets
which shot out in all directions and reached heights of up to 1,700 ft
(520 m). The base surge at its maximum size was 2.5 mi (4.0 km) in
diameter and 1,000 ft (300 m) high.
The heights of surface waves generated by deep underwater
explosions are greater because more energy is delivered to the water.
During the Cold War,
underwater explosions were thought to operate under the same principles
as tsunamis, potentially increasing dramatically in height as they move
over shallow water, and flooding the land beyond the shoreline.
Later research and analysis suggested that water waves generated by
explosions were different from those generated by tsunamis and
landslides. Méhauté et al. conclude in their 1996 overview Water Waves Generated by Underwater Explosion
that the surface waves from even a very large offshore undersea
explosion would expend most of their energy on the continental shelf,
resulting in coastal flooding no worse than that from a bad storm.
The Operation Wigwam test in 1955 occurred at a depth of 2,000 ft (610 m), the deepest detonation of any nuclear device.
Deep nuclear explosion
Expansion rate of blast bubble over timeOscillations in bubble sizeThe filaments of the Crab Nebula happen for the same reason
as the cold water filaments that extend into the blast bubble. This is
what an underwater nuclear explosion looks like, including the ellipsoid
("squished") shape.Expansion rate of blast bubble as a function of water pressureBubble oscillation period as a function of water pressure and blast sizePressure distribution in water near the blast bubble
Unless it breaks the water surface while still a hot gas bubble, an
underwater nuclear explosion leaves no trace at the surface but hot,
radioactive water rising from below. This is always the case with
explosions deeper than about 2,000 ft (610 m).
About one second after such an explosion, the hot gas bubble collapses because:
The water pressure is enormous below 2,000 feet (610 m).
The expansion reduces gas pressure, which decreases temperature.
Rayleigh–Taylor instability at the gas/water boundary causes "fingers" of water to extend into the bubble, increasing the boundary surface area.
Water is nearly incompressible.
Vast amounts of energy are absorbed by phase change (water becomes steam at the fireball boundary).
Expansion quickly becomes unsustainable because the amount of water pushed outward increases with the cube of the blast-bubble radius.
Since water is not readily compressible, moving this much of it out
of the way so quickly absorbs a massive amount of energy—all of which
comes from the pressure inside the expanding bubble. Water pressure
outside the bubble soon causes it to collapse back into a small sphere
and rebound, expanding again. This is repeated several times, but each
rebound contains only about 40% of the energy of the previous cycle.
At the maximum diameter of the first oscillation, a very large
nuclear bomb exploded in very deep water creates a bubble about a
half-mile (800 m) wide in about one second and then contracts, which
also takes about a second. Blast bubbles from deep nuclear explosions
have slightly longer oscillations than shallow ones. They stop
oscillating and become mere hot water in about six seconds. This
happens sooner in nuclear blasts than bubbles from conventional
explosives.
The water pressure of a deep explosion prevents any bubbles from surviving to float up to the surface.
The drastic 60% loss of energy between oscillation cycles is
caused in part by the extreme force of a nuclear explosion pushing the
bubble wall outward supersonically (faster than the speed of sound in
saltwater). This causes Rayleigh–Taylor instability.
That is, the smooth water wall touching the blast face becomes
turbulent and fractal, with fingers and branches of cold ocean water
extending into the bubble. That cold water cools the hot gas inside and
causes it to condense. The bubble becomes less of a sphere and looks
more like the Crab Nebula—the
deviation of which from a smooth surface is also due to Rayleigh–Taylor
instability as ejected stellar material pushes through the interstellar
medium.
As might be expected, large, shallow explosions expand faster than deep, small ones.
Despite being in direct contact with a nuclear explosion
fireball, the water in the expanding bubble wall does not boil; the
pressure inside the bubble exceeds (by far) the vapor pressure of water.
The water touching the blast can only boil during bubble contraction.
This boiling is like evaporation, cooling the bubble wall, and is
another reason that an oscillating blast bubble loses most of the energy
it had in the previous cycle.
During these hot gas oscillations, the bubble continually rises for the same reason a mushroom cloud
does: it is less dense. This causes the blast bubble never to be
perfectly spherical. Instead, the bottom of the bubble is flatter, and
during contraction, it even tends to "reach up" toward the blast center.
In the last expansion cycle, the bottom of the bubble touches the
top before the sides have fully collapsed, and the bubble becomes a torus
in its last second of life. About six seconds after detonation, all
that remains of a large, deep nuclear explosion is a column of hot water
rising and cooling in the near-freezing ocean.
List of underwater nuclear tests
Relatively few underwater nuclear tests were performed before they were banned by the Partial Test Ban Treaty. They are:
Note: it is often believed that the French did extensive underwater tests in French West Polynesia on the Moruroa and Fangataufa
Atolls. This is incorrect; the bombs were placed in shafts drilled into
the underlying coral and volcanic rock, and they did not intentionally
leak fallout.
Nuclear Test Gallery
Crossroads Baker
Operation Hurricane
Hardtack Umbrella
Dominic Swordfish
Underwater Nuclear Detonation Detection via Hydroacoustics
There are several methods of detecting nuclear detonations. Hydroacoustics is the primary means of determining if a nuclear detonation has occurred underwater. Hydrophones are used to monitor the change in water pressure as sound waves propagate through the world's oceans. Sound travels through 20 °C water at approximately 1482 meters per second, compared to the 332 m/s speed of sound through air.
In the world's oceans, sound travels most efficiently at a depth of
approximately 1000 meters. Sound waves that travel at this depth travel
at minimum speed and are trapped in a layer known as the Sound Fixing
and Ranging Channel (SOFAR).
Sounds can be detected in the SOFAR from large distances, allowing for a
limited number of monitoring stations required to detect oceanic
activity. Hydroacoustics was originally developed in the early 20th
century as a means of detecting objects like icebergs and shoals to
prevent accidents at sea.
Three hydroacoustic stations were built before the adoption of the Comprehensive Nuclear-Test-Ban Treaty. Two hydrophone stations were built in the North Pacific Ocean and Mid-Atlantic Ocean, and a T-phase
station was built off the west coast of Canada. When the CTBT was
adopted, 8 more hydroacoustic stations were constructed to create a
comprehensive network capable of identifying underwater nuclear
detonations anywhere in the world. These 11 hydroacoustic stations, in addition to 326 monitoring stations and laboratories, comprise the International Monitoring System (IMS), which is monitored by the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO).
There are two different types of hydroacoustic stations currently
used in the IMS network; 6 hydrophone monitoring stations and 5 T-phase
stations. These 11 stations are primarily located in the southern
hemisphere, which is primarily ocean.
Hydrophone monitoring stations consist of an array of three hydrophones
suspended from cables tethered to the ocean floor. They are positioned
at a depth located within the SOFAR in order to effectively gather
readings. Each hydrophone records 250 samples per second, while the tethering cable supplies power and carries information to the shore.
This information is converted to a usable form and transmitted via
secure satellite link to other facilities for analysis. T-phase
monitoring stations record seismic signals generate from sound waves
that have coupled with the ocean floor or shoreline. T-phase stations are generally located on steep-sloped islands in order to gather the cleanest possible seismic readings. Like hydrophone stations, this information is sent to the shore and transmitted via satellite link for further analysis.
Hydrophone stations have the benefit of gathering readings directly
from the SOFAR, but are generally more expensive to implement than
T-phase stations.
Hydroacoustic stations monitor frequencies from 1 to 100 Hertz to
determine if an underwater detonation has occurred. If a potential
detonation has been identified by one or more stations, the gathered
signals will contain a high bandwidth with the frequency spectrum
indicating an underwater cavity at the source.
Tongue depressor, a Class I medical device in the United StatesInfusion pump, a Class II medical device in the United StatesArtificial pacemaker, a Class III device in the United States
A medical device is any device intended to be used for medical purposes. Significant potential for hazards
are inherent when using a device for medical purposes and thus medical
devices must be proved safe and effective with reasonable assurance
before regulating governments allow marketing of the device in their
country. As a general rule, as the associated risk of the device
increases the amount of testing required to establish safety and
efficacy also increases. Further, as associated risk increases the
potential benefit to the patient must also increase.
Discovery of what would be considered a medical device by modern standards dates as far back as c. 7000 BC in Baluchistan where Neolithic dentists used flint-tipped drills and bowstrings. Study of archeology
and Roman medical literature also indicate that many types of medical
devices were in widespread use during the time of ancient Rome. In the United States it was not until the Federal Food, Drug, and Cosmetic Act
(FD&C Act) in 1938 that medical devices were regulated. Later in
1976, the Medical Device Amendments to the FD&C Act established
medical device regulation and oversight as we know it today in the
United States. Medical device regulation in Europe as we know it today came into effect in 1993 by what is collectively known as the Medical Device Directive (MDD). On May 26, 2017, the Medical Device Regulation (MDR) replaced the MDD.
The global medical device market was estimated to be between $220 and US$250 billion in 2013.
The United States controls ~40% of the global market followed by Europe
(25%), Japan (15%), and the rest of the world (20%). Although
collectively Europe has a larger share, Japan has the second largest
country market share. The largest market shares in Europe (in order of
market share size) belong to Germany, Italy, France, and the United
Kingdom. The rest of the world comprises regions like (in no particular
order) Australia, Canada, China, India, and Iran. This article discusses
what constitutes a medical device in these different regions and
throughout the article these regions will be discussed in order of their
global market share.
Definition
Medical devices were used for surgery in ancient Rome.
A global definition for medical device is difficult to establish
because there are numerous regulatory bodies worldwide overseeing the
marketing of medical devices. Although these bodies often collaborate
and discuss the definition in general, there are subtle differences in
wording that prevent a global harmonization
of the definition of a medical device, thus the appropriate definition
of a medical device depends on the region. Often a portion of the
definition of a medical device is intended to differentiate between
medical devices and drugs, as the regulatory requirements of the two are different. Definitions also often recognize In vitro diagnostics as a subclass of medical devices and establish accessories as medical devices.
Definitions by region
United States (Food and Drug Administration)
Section 201(h) of the Federal Food Drug & Cosmetic (FD&C) Act
defines a device as an "instrument, apparatus, implement, machine,
contrivance, implant, in vitro reagent, or other similar or related
article, including a component part, or accessory which is:
Intended for use in the diagnosis of disease or other conditions, or
in the cure, mitigation, treatment, or prevention of disease, in man or
other animals, or
Intended to affect the structure or any function of the body of man or other animals, and
which does not achieve its primary intended purposes through chemical
action within or on the body of man or other animals and which is not
dependent upon being metabolized for the achievement of its primary
intended purposes. The term 'device' does not include software functions
excluded pursuant to section 520(o)."
European Union
According to Article 1 of Council Directive 93/42/EEC,
'medical device' means any "instrument, apparatus, appliance, software,
material or other article, whether used alone or in combination,
including the software intended by its manufacturer to be used
specifically for diagnostic and/or therapeutic purposes and necessary
for its proper application, intended by the manufacturer to be used for
human beings for the purpose of:
diagnosis, prevention, monitoring, treatment or alleviation of disease,
diagnosis, monitoring, treatment, alleviation of or compensation for an injury or handicap,
investigation, replacement or modification of the anatomy or of a physiological process,
control of conception,
and which does not achieve its principal intended action in or on the human body by pharmacological, immunological or metabolic means, but which may be assisted in its function by such means;"
EU Legal framework
Based on the New Approach, rules that relate to safety and performance of medical devices were harmonised in the EU in the 1990s. The New Approach, defined in a European Council Resolution of May 1985,
represents an innovative way of technical harmonisation. It aims to
remove technical barriers to trade and dispel the consequent uncertainty
for economic operators, to facilitate free movement of goods inside the
EU.
The previous core legal framework consisted of three directives:
Directive 90/385/EEC regarding active implantable medical devices
Directive 93/42/EEC regarding medical devices
Directive 98/79/EC regarding in vitro diagnostic medical devices (Until 2022, the In Vitro Diagnosis Regulation (IVDR) will replace the EU's current Directive on In-Vitro Diagnostic (98/79/EC)).
They aim at ensuring a high level of protection of human health and
safety and the good functioning of the Single Market. These three main
directives have been supplemented over time by several modifying and
implementing directives, including the last technical revision brought
about by Directive 2007/47 EC.
The government of each Member State must appoint a competent authority responsible for medical devices. The competent authority
(CA) is a body with authority to act on behalf of the member state to
ensure that member state government transposes requirements of medical
device directives into national law and applies them. The CA reports to
the minister of health in the member state. The CA in one Member State
has no jurisdiction in any other member state, but exchanges information
and tries to reach common positions.
In the UK, for example, the Medicines and Healthcare products Regulatory Agency (MHRA) acted as a CA. In Italy it is the Ministero Salute (Ministry of Health) Medical devices must not be mistaken with medicinal products. In the EU, all medical devices must be identified with the CE mark. The conformity of a medium or high risk medical device with relevant regulations is also assessed by an external entity, the Notified Body, before it can be placed on the market.
In September 2012, the European Commission proposed new legislation aimed at enhancing safety, traceability, and transparency. The regulation was adopted in 2017.
The future core legal framework consists of two regulations, replacing the previous three directives:
Article 2, Paragraph 4, of the Pharmaceutical Affairs Law (PAL)
defines medical devices as "instruments and apparatus intended for use
in diagnosis, cure or prevention of diseases in humans or other animals;
intended to affect the structure or functions of the body of man or
other animals."
The term medical device, as defined in the Food and Drugs Act,
is "any article, instrument, apparatus or contrivance, including any
component, part or accessory thereof, manufactured, sold or represented
for use in: the diagnosis, treatment, mitigation or prevention of a
disease, disorder or abnormal physical state, or its symptoms, in a
human being; the restoration, correction or modification of a body
function or the body structure of a human being; the diagnosis of
pregnancy in a human being; or the care of a human being during
pregnancy and at and after the birth of a child, including the care of
the child. It also includes a contraceptive device but does not include a drug."
The term covers a wide range of health or medical instruments
used in the treatment, mitigation, diagnosis or prevention of a disease
or abnormal physical condition. Health Canada reviews medical devices to assess their safety, effectiveness, and quality before authorizing their sale in Canada. According to the Act, medical device does not include any device that is intended for use in relation to animals.
India
There is no specific definition of the term 'medical devices' in
Indian law. However, certain medical devices are notified as DRUGS
under the Drugs & Cosmetics Act. Section 3 (b) (iv) relating to
definition of "drugs" holds that "Devices intended for internal or
external use in the diagnosis, treatment, mitigation or prevention of
disease or disorder in human beings or animals" are also drugs. As of April 2022, 14 classes of devices are classified as drugs.
Regulation and oversight
Risk classification
A stethoscope (U.S. FDA product code BZS), a popular Class I medical device as determined by the U.S. FDA, ubiquitous in hospitals.
The regulatory authorities recognize different classes of medical
devices based on their potential for harm if misused, design complexity,
and their use characteristics. Each country or region defines these
categories in different ways. The authorities also recognize that some
devices are provided in combination with drugs, and regulation of these combination products takes this factor into consideration.
Classifying medical devices based on their risk is essential for
maintaining patient and staff safety while simultaneously facilitating
the marketing of medical products. By establishing different risk
classifications, lower risk devices, for example, a stethoscope or
tongue depressor, are not required to undergo the same level of testing
that higher risk devices such as artificial pacemakers undergo.
Establishing a hierarchy of risk classification allows regulatory bodies
to provide flexibility when reviewing medical devices.
Tongue, Electric Toothbrush, Bandages, Hospital Beds
Class II
Medium Risk
General Controls + Pre-Market Notification (510K)
Catheters, Contact Lenses, Pregnancy Test Kits
Class III
High Risk
General Controls + Special controls (510K) + Pre-Market Approval (PMA)
Pacemakers, Defibrillators, Implanted prosthetics, Breast implants
The classification procedures are described in the Code of Federal Regulations, Title 21, part 860 (usually known as 21 CFR 860).
Class I devices are subject to the least regulatory control and
are not intended to help support or sustain life or be substantially
important in preventing impairment to human health, and may not present
an unreasonable risk of illness or injury. Examples of Class I devices include elastic bandages, examination gloves, and hand-held surgical instruments.
Class II devices are subject to special labeling requirements, mandatory performance standards and postmarket surveillance.
Examples of Class II devices include acupuncture needles, powered
wheelchairs, infusion pumps, air purifiers, surgical drapes, stereotaxic
navigation systems, and surgical robots.
Class III devices are usually those that support or sustain human
life, are of substantial importance in preventing impairment of human
health, or present a potential, unreasonable risk of illness or injury
and require premarket approval.
Examples of Class III devices include implantable pacemakers, pulse
generators, HIV diagnostic tests, automated external defibrillators, and
endosseous implants.
European Union (EU) and European Free Trade Association (EFTA)
The
classification of medical devices in the European Union is outlined in
Article IX of the Council Directive 93/42/EEC and Annex VIII of the EU medical device regulation. There are basically four classes, ranging from low risk to high risk, Classes I, IIa, IIb, and III (this excludes in vitro diagnostics including software, which fall in four classes: from A (lowest risk) to D (highest risk)):
Device Class
Risk
Examples
Class I (Class I, Class Is, Class Im, Class Ir)
Low Risk
Tongue, Wheelchair, Spectacles
Class IIA
Medium Risk
Hearing aids
Class IIB
Medium to High Risk
Ventilators, Infusion pumps
Class III
High Risk
Pacemakers, Defibrillators, Implanted prosthetics, Breast implants
Class I Devices: Non-invasive, everyday devices or equipment.
Class I devices are generally low risk and can include bandages,
compression hosiery, or walking aids. Such devices require only for the
manufacturer to complete a Technical File.
Class Is Devices: Class Is devices are similarly
non-invasive devices, however this sub-group extends to include sterile
devices. Examples of Class Is devices include stethoscopes, examination
gloves, colostomy bags, or oxygen masks. These devices also require a
technical file, with the added requirement of an application to a
European Notified Body for certification of manufacturing in conjunction
with sterility standards.
Class Im Devices: This refers chiefly to similarly
low-risk measuring devices. Included in this category are: thermometers,
droppers, and non-invasive blood pressure measuring devices. Once again
the manufacturer must provide a technical file and be certified by a
European Notified Body for manufacturing in accordance with metrology
regulations.
Class IIa Devices: Class IIa devices generally constitute
low to medium risk and pertain mainly to devices installed within the
body in the short term. Class IIa devices are those which are installed
within the body for only between 60 minutes and 30 days. Examples
include hearing-aids, blood transfusion tubes, and catheters.
Requirements include technical files and a conformity test carried out
by a European Notified Body.
Class IIb Devices: Slightly more complex than IIa devices,
class IIb devices are generally medium to high risk and will often be
devices installed within the body for periods of 30 days or longer.
Examples include ventilators and intensive care monitoring equipment.
Identical compliance route to Class IIa devices with an added
requirement of a device type examination by a Notified Body.
Class III Devices: Class III devices are strictly high
risk devices. Examples include balloon catheters, prosthetic heart
valves, pacemakers, etc. The steps to approval here include a full
quality assurance system audit, along with examination of both the
device's design and the device itself by a European Notified Body.
The authorization of medical devices is guaranteed by a
Declaration of Conformity. This declaration is issued by the
manufacturer itself, but for products in Class Is, Im, Ir, IIa, IIb or
III, it must be verified by a Certificate of Conformity issued by a Notified Body.
A Notified Body is a public or private organisation that has been
accredited to validate the compliance of the device to the European
Directive. Medical devices that pertain to class I (on condition they do
not require sterilization or do not measure a function) can be marketed
purely by self-certification.
The European classification depends on rules that involve the
medical device's duration of body contact, invasive character, use of an
energy source, effect on the central circulation or nervous system,
diagnostic impact, or incorporation of a medicinal product. Certified
medical devices should have the CE mark on the packaging, insert leaflets, etc.. These packagings should also show harmonised pictograms and EN
standardised logos to indicate essential features such as instructions
for use, expiry date, manufacturer, sterile, don't reuse, etc.
In November 2018 the Federal Administrative Court of Switzerland
decided that the "Sympto" app, used to analyze a woman's menstrual
cycle, was a medical device because it calculates a fertility window for
each woman using personal data. The manufacturer, Sympto-Therm
Foundation, argued that this was a didactic, not a medical process. the
court laid down that an app
is a medical device if it is to be used for any of the medical purposes
provided by law, and creates or modifies health information by
calculations or comparison, providing information about an individual
patient.
Japan
Medical devices (excluding in vitro diagnostics) in Japan are classified into four classes based on risk:
Device Class
Risk
Class I
Insignificant
Class II
Low
Class III
High Risk on Malfunction
Class IV
High Risk could cause life-threatening
Classes I and II distinguish between extremely low and low risk
devices. Classes III and IV, moderate and high risk respectively, are
highly and specially controlled medical devices. In vitro diagnostics
have three risk classifications.
Rest of the world
For
the remaining regions in the world the risk classifications are
generally similar to the United States, European Union, and Japan or are
a variant combining two or more of the three countries' risk
classifications.
Australia
The
classification of medical devices in Australia is outlined in section
41BD of the Therapeutic Goods Act 1989 and Regulation 3.2 of the
Therapeutic Goods Regulations 2002, under control of the Therapeutic Goods Administration.
Similarly to the EU classification, they rank in several categories, by
order of increasing risk and associated required level of control.
Various rules identify the device's category
Medical device categories in Australia
Classification
Level of risk
Class I
Low
Class I - measuring or Class I - supplied sterile or class IIa
The Medical Devices Bureau of Health Canada
recognizes four classes of medical devices based on the level of
control necessary to assure the safety and effectiveness of the device.
Class I devices present the lowest potential risk and do not require a
licence. Class II devices require the manufacturer's declaration of
device safety and effectiveness, whereas Class III and IV devices
present a greater potential risk and are subject to in-depth scrutiny. A guidance document for device classification is published by Health Canada.
Canadian classes of medical devices correspond to the European Council Directive 93/42/EEC (MDD) devices:
Class I (Canada) generally corresponds to Class I (ECD)
Class II (Canada) generally corresponds to Class IIa (ECD)
Class III (Canada) generally corresponds to Class IIb (ECD)
Class IV (Canada) generally corresponds to Class III (ECD)
Examples include surgical instruments (Class I), contact lenses and ultrasound scanners (Class II), orthopedic implants and hemodialysis machines (Class III), and cardiac pacemakers (Class IV).
India
Medical devices in India are regulated by Central Drugs Standard Control Organisation (CDSCO).
Medical devices under the Medical Devices Rules, 2017 are classified as
per Global Harmonization Task Force (GHTF) based on associated risks.
The CDSCO classifications of medical devices govern alongside the
regulatory approval and registration by the CDSCO is under the DCGI.
Every single medical device in India pursues a regulatory framework that
depends on the drug guidelines under the Drug and Cosmetics Act (1940)
and the Drugs and Cosmetics runs under 1945. CDSCO classification for
medical devices has a set of risk classifications for numerous products
planned for notification and guidelines as medical devices.
Device Class
Risk
Examples
Class A
Low Risk
Tongue, Wheelchair, Spectacles, Alcohol Swab
Class B
Low to Moderate Risk
Hearing aids, Thermometer
Class C
Moderate to High Risk
Ventilators, Infusion pumps
Class D
High Risk
Pacemakers, Defibrillators, Implanted prosthetics, Breast implants
Iran
produces about 2,000 types of medical devices and medical supplies, such
as appliances, dental supplies, disposable sterile medical items,
laboratory machines, various biomaterials and dental implants. 400
Medical products are produced at the C and D risk class with all of them
licensed by the Iranian Health Ministry in terms of safety and
performance based on EU-standards.
Some Iranian medical devices are produced according to the European Union standards.
Some producers in Iran export medical devices and supplies which adhere to European Union standards to applicant countries, including 40 Asian and European countries.
Some Iranian producers export their products to foreign countries.
The main difference between the two is that validation is focused
on ensuring that the device meets the needs and requirements of its
intended users and the intended use environment, whereas verification is
focused on ensuring that the device meets its specified design
requirements.
Standardization and regulatory concerns
The ISO standards for medical devices are covered by ICS 11.100.20 and 11.040.01. The quality and risk management regarding the topic for regulatory purposes is convened by ISO 13485 and ISO 14971.
ISO 13485:2016 is applicable to all providers and manufacturers of
medical devices, components, contract services and distributors of
medical devices. The standard is the basis for regulatory compliance in local markets, and most export markets. Additionally, ISO 9001:2008
sets precedence because it signifies that a company engages in the
creation of new products. It requires that the development of
manufactured products have an approval process and a set of rigorous
quality standards and development records before the product is
distributed. Further standards are IEC 60601-1 which is for electrical devices (mains-powered as well as battery powered), EN 45502-1 which is for Active implantable medical devices, and IEC 62304 for medical software. The US FDA also published a series of guidances for industry regarding this topic against 21 CFR 820 Subchapter H—Medical Devices. Subpart B includes quality system requirements, an important component of which are design controls
(21 CFR 820.30). To meet the demands of these industry regulation
standards, a growing number of medical device distributors are putting
the complaint management process at the forefront of their quality management practices. This approach further mitigates risks and increases visibility of quality issues.
Starting in the late 1980s
the FDA increased its involvement in reviewing the development of
medical device software. The precipitant for change was a radiation
therapy device (Therac-25) that overdosed patients because of software coding errors. FDA is now focused on regulatory oversight on medical device software development process and system-level testing.
A 2011 study by Dr. Diana Zuckerman and Paul Brown of the National Center for Health Research, and Dr. Steven Nissen of the Cleveland Clinic, published in the Archives of Internal Medicine,
showed that most medical devices recalled in the last five years for
"serious health problems or death" had been previously approved by the
FDA using the less stringent, and cheaper, 510(k) process. In a few
cases, the devices had been deemed so low-risk that they did not they
did not undergo any FDA regulatory review. Of the 113 devices recalled,
35 were for cardiovascular issues. This study was the topic of Congressional hearings re-evaluating FDA procedures and oversight.
A 2014 study by Dr. Diana Zuckerman, Paul Brown, and Dr. Aditi Das of the National Center for Health Research,
published in JAMA Internal Medicine, examined the scientific evidence
that is publicly available about medical implants that were cleared by
the FDA 510(k) process from 2008 to 2012. They found that scientific
evidence supporting "substantial equivalence" to other devices already
on the market was required by law to be publicly available, but the
information was available for only 16% of the randomly selected
implants, and only 10% provided clinical data. Of the more than 1,100
predicate implants that the new implants were substantially equivalent
to, only 3% had any publicly available scientific evidence, and only 1%
had clinical evidence of safety or effectiveness. The researchers concluded that publicly available scientific evidence on implants was needed to protect the public health.
In
2014-2015 a new international agreement, the Medical Device Single
Audit Program (MDSAP), was put in place with five participant countries:
Australia, Brazil, Canada, Japan, and the United States. The aim of
this program was to "develop a process that allows a single audit, or
inspection to ensure the medical device regulatory requirements for all
five countries are satisfied".
In 2017, a study by Dr. Jay Ronquillo and Dr. Diana Zuckerman
published in the peer-reviewed policy journal Milbank Quarterly found
that electronic health records and other device software were recalled
due to life-threatening flaws. The article pointed out the lack of
safeguards against hacking and other cybersecurity threats, stating
"current regulations are necessary but not sufficient for ensuring
patient safety by identifying and eliminating dangerous defects in
software currently on the market".
They added that legislative changes resulting from the law entitled the
21st Century Cures Act "will further deregulate health IT, reducing
safeguards that facilitate the reporting and timely recall of flawed
medical software that could harm patients".
A study by Dr. Stephanie Fox-Rawlings and colleagues at the
National Center for Health Research, published in 2018 in the policy
journal Milbank Quarterly, investigated whether studies reviewed by the
FDA for high-risk medical devices are proven safe and effective for
women, minorities, or patients over 65 years of age.
The law encourages patient diversity in clinical trials submitted to
the FDA for review, but does not require it. The study determined that
most high-risk medical devices are not tested and analyzed to ensure
that they are safe and effective for all major demographic groups,
particularly racial and ethnic minorities and people over 65. Therefore,
they do not provide information about safety or effectiveness that
would help patients and physicians make well informed decisions.
In 2018, an investigation involving journalists across 36 countries coordinated by the International Consortium of Investigative Journalists (ICIJ) prompted calls for reform in the United States, particularly around the 510(k) substantial equivalence process; the investigation prompted similar calls in the UK and Europe Union.
Packaging standards
Curette in sterile pouch. Porous tyvek material allows gas sterilization
Medical device packaging is highly regulated. Often medical devices and products are sterilized in the package.
Sterility must be maintained throughout distribution to allow immediate use by physicians. A series of special packaging tests measure the ability of the package to maintain sterility. Relevant standards include:
ASTM F2097 – Standard Guide for Design and Evaluation of Primary Flexible Packaging for Medical Products
ASTM F2475-11 – Standard Guide for Biocompatibility Evaluation of Medical Device Packaging Materials
EN 868 Packaging materials and systems for medical devices to be sterilized, General requirements and test methods
ISO 11607 Packaging for terminally sterilized medical devices
Package testing is part of a quality management system including verification and validation.
It is important to document and ensure that packages meet regulations
and end-use requirements. Manufacturing processes must be controlled and
validated to ensure consistent performance. EN ISO 15223-1 defines symbols that can be used to convey important information on packaging and labeling.
Biocompatibility standards
ISO 10993 - Biological Evaluation of Medical Devices
Cleanliness standards
Medical
device cleanliness has come under greater scrutiny since 2000, when
Sulzer Orthopedics recalled several thousand metal hip implants that
contained a manufacturing residue.
Based on this event, ASTM established a new task group (F04.15.17) for
established test methods, guidance documents, and other standards to
address cleanliness of medical devices. This task group has issued two
standards for permanent implants to date: 1. ASTM F2459: Standard test
method for extracting residue from metallic medical components and
quantifying via gravimetric analysis 2. ASTM F2847: Standard Practice for Reporting and Assessment of Residues on Single Use Implants 3. ASTM F3172: Standard Guide for Validating Cleaning Processes Used During the Manufacture of Medical Devices.
In addition, the cleanliness of re-usable devices has led to a series of standards, including:
ASTM E2314: Standard Test Method for Determination of
Effectiveness of Cleaning Processes for Reusable Medical Instruments
Using a Microbiologic Method (Simulated Use Test)"
ASTM D7225: Standard Guide for Blood Cleaning Efficiency of Detergents and Washer-Disinfectors
ASTM F3208: Standard Guide for Selecting Test Soils for Validation of Cleaning Methods for Reusable Medical Devices
The ASTM F04.15.17 task group is working on several new standards
that involve designing implants for cleaning, selection and testing of
brushes for cleaning reusable devices, and cleaning assessment of
medical devices made by additive manufacturing.
Additionally, the FDA is establishing new guidelines for reprocessing
reusable medical devices, such as orthoscopic shavers, endoscopes, and
suction tubes. New research was published in ACS Applied Interfaces and Material to keep Medical Tools pathogen free.
Medical device manufacturing requires a level of process control
according to the classification of the device. Higher risk; more
controls. When in the initial R&D phase, manufacturers are now
beginning to design for manufacturability. This means products can be
more precision-engineered to for production to result in shorter lead
times, tighter tolerances and more advanced specifications and
prototypes. These days, with the aid of CAD or modelling platforms, the
work is now much faster, and this can act also as a tool for strategic
design generation as well as a marketing tool.
Failure to meet cost targets will lead to substantial losses for
an organisation. In addition, with global competition, the R&D of
new devices is not just a necessity, it is an imperative for medical
device manufacturers. The realisation of a new design can be very
costly, especially with the shorter product life cycle. As technology
advances, there is typically a level of quality, safety and reliability
that increases exponentially with time.
For example, initial models of the artificial cardiac pacemaker
were external support devices that transmits pulses of electricity to
the heart muscles via electrode leads on the chest. The electrodes
contact the heart directly through the chest, allowing stimulation
pulses to pass through the body. Recipients of this typically developed
an infection at the entrance of the electrodes, which led to the
subsequent trial of the first internal pacemaker, with electrodes
attached to the myocardium by thoracotomy. Future developments led to
the isotope-power source that would last for the lifespan of the
patient.
With the rise of smartphone usage in the medical space, in 2013, the FDA issued to regulate mobile medical applications
and protect users from their unintended use, soon followed by European
and other regulatory agencies. This guidance distinguishes the apps
subjected to regulation based on the marketing claims of the apps.
Incorporation of the guidelines during the development phase of such
apps can be considered as developing a medical device; the regulations
have to adapt and propositions for expedite approval may be required due
to the nature of 'versions' of mobile application development.
On September 25, 2013, the FDA released a draft guidance document
for regulation of mobile medical applications, to clarify what kind of
mobile apps related to health would not be regulated, and which would
be.
Medical devices such as pacemakers, insulin pumps, operating room monitors, defibrillators, and surgical instruments, including deep-brain stimulators, can incorporate the ability to transmit vital health information from a patient's body to medical professionals. Some of these devices can be remotely controlled. This has engendered concern about privacy and security issues, human error,
and technical glitches with this technology. While only a few studies
have looked at the susceptibility of medical devices to hacking, there
is a risk.
In 2008, computer scientists proved that pacemakers and defibrillators
can be hacked wirelessly via radio hardware, an antenna, and a personal
computer.
These researchers showed they could shut down a combination heart
defibrillator and pacemaker and reprogram it to deliver potentially
lethal shocks or run out its battery. Jay Radcliff, a security
researcher interested in the security of medical devices, raised fears
about the safety of these devices. He shared his concerns at the Black
Hat security conference.
Radcliff fears that the devices are vulnerable and has found that a
lethal attack is possible against those with insulin pumps and glucose
monitors. Some medical device makers downplay the threat from such
attacks and argue that the demonstrated attacks have been performed by
skilled security researchers and are unlikely to occur in the real
world. At the same time, other makers have asked software security
experts to investigate the safety of their devices.
As recently as June 2011, security experts showed that by using readily
available hardware and a user manual, a scientist could both tap into
the information on the system of a wireless insulin pump in combination
with a glucose monitor. With the PIN of the device, the scientist could
wirelessly control the dosage of the insulin.
Anand Raghunathan, a researcher in this study, explains that medical
devices are getting smaller and lighter so that they can be easily worn.
The downside is that additional security features would put an extra
strain on the battery and size and drive up prices. Dr. William Maisel
offered some thoughts on the motivation to engage in this activity.
Motivation to do this hacking might include acquisition of private
information for financial gain or competitive advantage; damage to a
device manufacturer's reputation; sabotage; intent to inflict financial
or personal injury or just satisfaction for the attacker.
Researchers suggest a few safeguards. One would be to use rolling
codes. Another solution is to use a technology called "body-coupled
communication" that uses the human skin as a wave guide for wireless
communication. On 28 December 2016 the US Food and Drug Administration released its recommendations that are not legally enforceable for how medical device manufacturers should maintain the security of Internet-connected devices.
Similar to hazards, cybersecurity threats and vulnerabilities
cannot be eliminated but must be managed and reduced to a reasonable
level.
When designing medical devices, the tier of cybersecurity risk should
be determined early in the process in order to establish a cybersecurity
vulnerability and management approach (including a set of cybersecurity
design controls). The medical device design approach employed should be consistent with the NIST Cybersecurity Framework for managing cybersecurity-related risks.
In August 2013, the FDA released over 20 regulations aiming to improve the security of data in medical devices, in response to the growing risks of limited cybersecurity.
Artificial intelligence
The
number of approved medical devices using artificial intelligence or
machine learning (AI/ML) is increasing. As of 2020, there were several
hundred AI/ML medical devices approved by the US FDA or CE-marked
devices in Europe.
Most AI/ML devices focus upon radiology. As of 2020, there was no
specific regulatory pathway for AI/ML-based medical devices in the US or
Europe. However, in January 2021, the FDA published a proposed regulatory framework for AI/ML-based software,and the EU medical device regulation
which replaces the EU Medical Device Directive in May 2021, defines
regulatory requirements for medical devices, including AI/ML software.
Medical monitors
allow medical staff to measure a patient's medical state. Monitors may
measure patient vital signs and other parameters including ECG, EEG, and blood pressure.
Diagnostic medical equipment may also be used in the home for certain purposes, e.g. for the control of diabetes mellitus, such as in the case of Continuous Glucose Monitoring.
Air purifying equipment may be used in the periphery of the operating room or at point sources including near the surgical site for the removal of surgical plume.
The identification of medical devices has been recently improved by the introduction of Unique Device Identification (UDI) and standardised naming using the Global Medical Device Nomenclature (GMDN) which have been endorsed by the International Medical Device Regulatory Forum (IMDRF).
A biomedical equipment technician (BMET)
is a vital component of the healthcare delivery system. Employed
primarily by hospitals, BMETs are the people responsible for maintaining
a facility's medical equipment. BMET mainly act as an interface between
doctor and equipment.
Medical equipment donation
There are challenges surrounding the availability of medical equipment from a global health
perspective, with low-resource countries unable to obtain or afford
essential and life-saving equipment. In these settings, well-intentioned
equipment donation from high- to low-resource settings is a frequently
used strategy to address this through individuals, organisations,
manufacturers and charities. However, issues with maintenance,
availability of biomedical equipment technicians (BMET),
supply chains, user education and the appropriateness of donations
means these frequently fail to deliver the intended benefits. The WHO
estimates that 95% of medical equipment in low- and middle-income
countries (LMICs) is imported and 80% of it is funded by international
donors or foreign governments. While up to 70% of medical equipment in
sub-Saharan Africa is donated, only 10%–30% of donated equipment becomes
operational.
A review of current practice and guidelines for the donation of medical
equipment for surgical and anaesthesia care in LMICs has demonstrated a
high level of complexity within the donation process and numerous
shortcomings. Greater collaboration and planning between donors and
recipients is required together with evaluation of donation programs and
concerted advocacy to educate donors and recipients on existing
equipment donation guidelines and policies.
The circulation of medical equipment is not limited to donations.
The rise of reuse and recycle-based solutions, where gently-used
medical equipment is donated and redistributed to communities in need,
is another form of equipment distribution. An interest in reusing and
recycling emerged in the 1980s when the potential health hazards of
medical waste on the East Coast beaches became highlighted by the media.
Connecting the large demand for medical equipment and single-use
medical devices, with a need for waste reduction, as well as the problem
of unequal access for low-income communities led to the Congress
enacting the Medical Waste Tracking Act of 1988. Medical equipment can be donated either by governments or non-governmental organizations, domestic or international. Donated equipment ranges from bedside assistance to radiological equipment.
Medical equipment donation has come under scrutiny with regard to
donated-device failure and loss of warranty in the case of
previous-ownership. Most medical devices and production company
warranties to do not extend to reused or donated devices, or to devices
donated by initial owners/patients. Such reuse raises matters of patient
autonomy, medical ethics, and legality.
Such concerns conflict with the importance of equal access to
healthcare resources, and the goal of serving the greatest good for the
greatest number.
_on_11_May_1962.jpg)
_-_n._11141_-_Museo_di_Napoli_-_Strumenti_di_chirurgia.jpg)
