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Table of Contents 1 What is a medical device ?.....................................................................................................................1

1.1 European Union definition.............................................................................................................2 1.2 Definition in USA by the Food and Drug Administration..............................................................2 1.3 Classification..................................................................................................................................3 1.4 List of medical devices...................................................................................................................3

1.4.1 High risk devices....................................................................................................................3 1.4.2 Medium risk devices..............................................................................................................4 1.4.3 Low risk devices.....................................................................................................................4

1.5 Standardization & regulatory concerns..........................................................................................5 2 Patient care and monitoring ..................................................................................................................5

2.1 Mechanical Ventilation...................................................................................................................6 2.1.1 General....................................................................................................................................6 2.1.2 Types of ventilators.................................................................................................................7

2.2 Biotelemetry...................................................................................................................................8 2.3 Artificial pacemakers....................................................................................................................11

2.3.1 Temporary pacing.................................................................................................................12 2.3.1.1 Percussive Pacing..........................................................................................................12 2.3.1.2 Transcutaneous Pacing..................................................................................................13 2.3.1.3 Epicardial Pacing..........................................................................................................13 2.3.1.4 Transvenous Pacing......................................................................................................13

2.3.2 Permanent pacing..................................................................................................................13 2.4 Defibrillation................................................................................................................................15 2.5 Dialysis.........................................................................................................................................16

2.5.1 Hemodialysis........................................................................................................................17 2.5.2 Peritoneal dialysis.................................................................................................................18

2.6 Medical monitoring......................................................................................................................19 2.7 Intravenous therapy......................................................................................................................20 2.8 Nanogastric intubation.................................................................................................................20 2.9 Pulse oximetry..............................................................................................................................21

1 What is a medical device ?

A medical device is a product which is used for medical purposes in patients, in diagnosis, therapy or

surgery. If applied to the body, the effect of the medical device is primarily physical, in contrast to

pharmaceutical drugs, which exert a biochemical effect. Specific regional definitions of medical device

vary slightly as detailed below. The medical devices are included in the category Medical technology.

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Medical devices include a wide range of products varying in complexity and application. Examples

include tongue depressors, medical thermometers, blood sugar meters, and X-ray machines.

1.1 European Union definition

Directive 2007/47/ec of the European Parliament and of the council of 5 September, 2007, which

amended the Council Directive 93/42/EEC of 14 June, 1993 concerning medical devices, defines a

medical device as 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. Devices are to be used 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

This includes devices that do 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.

The Medicines and Healthcare products Regulatory Agency (MHRA) regulates medical devices in the

UK under European legislation. Medical devices must not be mistaken with medicinal products. In the

EU, all medical devices must be identified with the CE mark.

1.2 Definition in USA by the Food and Drug Administration

A medical device, according to the U.S. Food and Drug Administration (FDA), is an instrument,

apparatus, implement, machine, contrivance, implant, in vitro reagent, or other similar or related

article, including a component part, or accessory which is:

• recognized in the official National Formulary, or the United States Pharmacopoeia, or any

supplement to them,

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• 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 any of 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 any of its primary intended purposes.

as defined by the Federal Food, Drug, and Cosmetic Act, 21 United States Code [321] (h). Medical

devices are regulated by the FDA Center for Devices and Radiological Health (CDRH).

1.3 Classification

The regulatory authorities in recognize different classes of medical devices, based on their design

complexity, their use characteristics, and their potential for harm if misused. 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.

1.4 List of medical devices

1.4.1 High risk devicesHigh risk devices are life supports, critical monitoring, energy emitting and other devices whose failure

or misuse is reasonably likely to seriously injure patient or staff. Examples include:

• Anesthesia ventilators

• Anesthesia units

• Apnea monitors

• Argon enhanced coagulation units

• Aspirators

• Auto transfusion units

• Invasive Blood pressure units

• Fetal monitors

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• Electrosurgical units

• Incubators

• Infusion pump

• Pulse oximeters

• External pacemaker

• Heart Lung Machine

1.4.2 Medium risk devicesThese are devices including many diagnostic instruments whose misuse, failure or absence (e.g. out

of service) with no replacement available would have a significant impact on patient care, but would

not be likely to cause direct serious injury. Examples include:

• ECG

• EEG

• Treadmills

• Ultrasound sensors

• Phototherapy units

• Endoscopes

• Surgical drill and saws

• Laparoscopic insufflators

• Phonocardiographs

• radiant warmers (Adult)

• Zoophagous agents (e.g., medicinal leeches; medicinal maggots)

• Lytic Bacteriophages

1.4.3 Low risk devicesDevices in this category are those whose failure or misuse is unlikely to result in serious

consequences. Examples include:

• Electronic thermometer,

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• Breast pumps

• Surgical microscope

• Ultrasonic nebulizers

• Sphygmomanometers

• Surgical table

• Surgical lights.

• Temperature monitor

• Aspirators

• X-rays diagnostic equipment

1.5 Standardization & regulatory concerns

The ISO standards for medical devices are covered by ICS 11.100.20 and 11.040.01 [5], [6]. The

quality and risk management regarding the topic for regulatory purposes is convened by ISO 13485

and ISO 14971. Further standards are IEC 60601-1 and for medical software IEC 62304. USFDA also

published a series of guidances for industry regarding this topic against 21 CFR Subchapter H--

Medical Devices.[

2 Patient care and monitoring

An intensive care unit (ICU), critical care unit (CCU), intensive therapy unit or intensive treatment unit (ITU) is a specialized department used in many countries' hospitals that provides

intensive care medicine. Many hospitals also have designated intensive care areas for certain

specialities of medicine, as dictated by the needs and available resources of each hospital. The

naming is not rigidly standardized.

Common equipment in an ICU includes mechanical ventilator to assist breathing through an

endotracheal tube or a tracheotomy opening; cardiac monitors including telemetry, external

pacemakers, and defibrillators; dialysis equipment for renal problems; equipment for the constant

monitoring of bodily functions; a web of intravenous lines, feeding tubes, nasogastric tubes, suction

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pumps, drains and catheters; and a wide array of drugs to treat the main condition(s). Medically

induced comas, analgesics, and induced sedation reduce pain and prevent secondary infections.

2.1 Mechanical Ventilation

2.1.1 GeneralIn medicine, mechanical ventilation is a method to

mechanically assist or replace spontaneous breathing.

This may involve a machine called a ventilator or the

breathing may be assisted by a physician or other

suitable person compressing a bag or set of bellows.

Traditionally divided into negative-pressure ventilation,

where air is essentially sucked into the lungs, or positive

pressure ventilation, where air (or another gas mix) is

pushed into the trachea.

It can be used as a short term measure, for example

during an operation or critical illness (often in the setting

of an intensive care unit). It may be used at home or in a

nursing or rehabilitation institution if patients have chronic

illnesses that require long-term ventilatory assistance.

Owing to the anatomy of the human pharynx,larynx and oesophagus and the circumstances for which

ventilation is required then additional measures are often required to "secure" the airway during

positive pressure ventilation to allow unimpeded passage of air into the trachea and avoid air passing

into the oesophagus and stomach. Commonly this is by insertion of a tube into the trachea which

provides a clear route for the air. This can be either an endotracheal tube, inserted through the natural

openings of mouth or nose or a tracheostomy inserted through an artificial opening in the neck. In

other circumstances simple airway manouevres, an oropharyngeal airway or laryngeal mask airway

may be employed. If the patient is able to protect their own airway such as in non-invasive ventilation

or negative pressure ventilation then no airway adjunct may be needed.

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Mechanical ventilation is often a life-saving intervention, but carries many potential complications

including pneumothorax, airway injury, alveolar damage,

and ventilator-associated pneumonia.[citation needed].

In many healthcare systems prolonged ventilation as part

of intensive care is a limited resource (in that there are

only so many patients that can receive care at any given

moment). It is used to support a single failing organ

system (the lungs) and cannot reverse any underlying

disease process (such as terminal cancer). For this

reason there can be (occasionally difficult) decisions to

be made about whether it is suitable to commence

someone on mechanical ventilation. Equally many ethical

issues surround the decision to discontinue mechanical ventilation.

2.1.2 Types of ventilatorsVentilation can be delivered via:

• Hand-controlled ventilation such as:

SMART BAG MO Bag-Valve-Mask Resuscitator

• Bag valve mask

• Continuous-flow or Anaesthesia (or T-piece) bag

• A mechanical ventilator. Types of mechanical ventilators include:

• Transport ventilators. These ventilators are small, more rugged, and can be powered

pneumatically or via AC or DC power sources.

• ICU ventilators. These ventilators are larger and usually run on AC power (though

virtually all contain a battery to facilitate intra-facility transport and as a back-up in the

event of a power failure). This style of ventilator often provides greater control of a wide

variety of ventilation parameters (such as inspiratory rise time). Many ICU ventilators

also incorporate graphics to provide visual feedback of each breath.

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• NICU ventilators.

Designed with the

preterm neonate in mind,

these are a specialized

subset of ICU ventilators

which are designed to

deliver the smaller, more

precise volumes and

pressures required to

ventilate these patients.

• PAP ventilators. these ventilators

are specifically designed for non-

invasive ventilation. this includes

ventilators for use at home, in

order to treat sleep apnea.

2.2 Biotelemetry

Biotelemetry (or Medical Telemetry) involves the application of telemetry in the medical field to

remotely monitor various vital signs of ambulatory patients.

The most common usage for biotelemetry is in dedicated cardiac care telemetry units or step-down

units in hospitals. Although virtually any physiological signal could be transmitted, application is

typically limited to EKG and SpO2.

A typical biotelemetry system comprises:

• Sensors appropriate for the particular signals to be monitored

• Battery-powered, Patient worn transmitters

• A Radio Antenna and Receiver

• A display unit capable of concurrently presenting information from multiple patients

• Animal tracking

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Because of crowding of the radio spectrum due to the recent introduction of HDTV in the United States

and many other countries, the FCC as well as similar agencies elsewhere have recently begun to

allocate dedicated frequency bands for exclusive biotelemetry usage, for example, the Wireless

Medical Telemetry Service (WMTS). The FCC has designated the American Society for Healthcare

Engineering of the American Hospital Association (ASHE/AHA) as the frequency coordinator for the

Wireless Medical Telemetry Service (WMTS).

In addition, there are many products that utilize commonly available standard radio devices such as

Bluetooth and IEEE 802.11.

Telemetry is also used for patients who are at risk of abnormal heart activity, generally in a coronary

care unit. Such patients are outfitted with measuring, recording and transmitting devices. A data log

can be useful in diagnosis of the patient's condition by doctors. An alerting function can alert nurses if

the patient is suffering from an acute or dangerous condition.

Also a system that is available in medical-surgical nursing to monitor a condition where heart condition

may be ruled out. Or to monitor a response to antiarrhythmic medications such as Digoxin.

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2.3 Artificial pacemakers

A pacemaker (or artificial pacemaker, so as not to be confused with the heart's natural pacemaker)

is a medical device which uses electrical impulses, delivered by electrodes contacting the heart

muscles, to regulate the beating of the heart. The primary purpose of a pacemaker is to maintain an

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adequate heart rate, either because the heart's native pacemaker is not fast enough, or there is a

block in the heart's electrical conduction system. Modern pacemakers are externally programmable

and allow the cardiologist to select the optimum pacing modes for individual patients. Some combine a

pacemaker and defibrillator in a single implantable device. Others have multiple electrodes stimulating

differing positions within the heart to improve synchronisation of the lower chambers of the heart.

2.3.1 Temporary pacing

2.3.1.1 Percussive PacingPercussive Pacing, also known as Transthoracic Mechanical Pacing, is the use of the closed fist,

usually on the left lower edge of the sternum over the right ventricle in the vena cava, striking from a

distance of 20 - 30 cm to induce a ventricular beat (the British Journal of Anesthesia suggests this

must be done to raise the ventricular pressure to 10 - 15mmhg to induce electrical activity). This is an

old procedure used only as a life saving means until an electrical pacemaker is brought to the patient.

[16]

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2.3.1.2 Transcutaneous Pacing

Transcutaneous pacing (TCP), also called external pacing, is recommended for the initial stabilization

of hemodynamically significant bradycardias of all types. The procedure is performed by placing two

pacing pads on the patient's chest, either in the anterior/lateral position or the anterior/posterior

position. The rescuer selects the pacing rate, and gradually increases the pacing current (measured in

mA) until electrical capture (characterized by a wide QRS complex with a tall, broad T wave on the

ECG) is achieved, with a corresponding pulse. Pacing artifact on the ECG and severe muscle

twitching may make this determination difficult. External pacing should not be relied upon for an

extended period of time. It is an emergency procedure that acts as a bridge until transvenous pacing

or other therapies can be applied.

2.3.1.3 Epicardial Pacing

Temporary epicardial pacing is used during open heart surgery should the surgical procedure create

atrio ventricular block. The electrodes are placed in contact with the outer wall of the ventricle

(epicardium) to maintain satisfactory cardiac output until a temporary transvenous electrode has been

inserted.

2.3.1.4 Transvenous Pacing

Transvenous pacing, when used for temporary pacing, is an alternative to transcutaneous pacing. A

pacemaker wire is placed into a vein, under sterile conditions, and then passed into either the right

atrium or right ventricle. The pacing wire is then connected to an external pacemaker outside the body.

Transvenous pacing is often used as a bridge to permanent pacemaker placement. It can be kept in

place until a permanent pacemaker is implanted or until there is no longer a need for a pacemaker and

then it is removed.

2.3.2 Permanent pacing

Permanent pacing with an implantable pacemaker involves transvenous placement of one or more

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pacing electrodes within a chamber, or chambers, of the heart. The procedure is performed by incision

of a suitable vein into which the electrode lead is inserted and passed along the vein, through the

valve of the heart, until positioned in the chamber. The procedure is facilitated by fluoroscopy which

enables the physician or cardiologist to view the passage of the electrode lead. After satisfactory

lodgement of the electrode is confirmed the opposite end of the electrode lead is connected to the

pacemaker generator.

There are three basic types of permanent pacemakers, classified according to the number of

chambers involved and their basic operating mechanism:[17]

• Single-chamber pacemaker. In this type, only one pacing lead is placed into a chamber of the

heart, either the atrium or the ventricle.[17]

• Dual-chamber pacemaker. Here, wires are placed in two chambers of the heart. One lead

paces the atrium and one paces the ventricle. This type more closely resembles the natural

pacing of the heart by assisting the heart in coordinating the function between the atria and

ventricles.[17]

• Rate-responsive pacemaker. This pacemaker has sensors that detect changes in the patient's

physical activity and automatically adjust the pacing rate to fulfill the body's metabolic needs.

[17]

The pacemaker generator is a hermetically sealed device containing a power source, usually a lithium

battery, a sensing amplifier which processes the electrical manifestation of naturally occurring heart

beats as sensed by the heart electrodes, the computer logic for the pacemaker and the output circuitry

which delivers the pacing impulse to the electrodes.

Most commonly, the generator is placed below the subcutaneous fat of the chest wall, above the

muscles and bones of the chest. However, the placement may vary on a case by case basis.

The outer casing of pacemakers is so designed that it will rarely be rejected by the body's immune

system. It is usually made of titanium, which is inert in the body. The whole thing will not be rejected,

and will be encapsulated by scar tissue, in the same way a piercing is.

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2.4 Defibrillation

Defibrillation is the definitive treatment for the life-

threatening cardiac arrhythmias, ventricular fibrillation

and pulseless ventricular tachycardia. Defibrillation

consists of delivering a therapeutic dose of electrical

energy to the affected heart with a device called a

defibrillator. This depolarizes a critical mass of the

heart muscle, terminates the arrhythmia, and allows

normal sinus rhythm to be reestablished by the body's

natural pacemaker, in the sinoatrial node of the heart.

Defibrillators can be external, transvenous, or

implanted, depending on the type of device used or

needed. Some external units, known as automated

external defibrillators (AEDs), automate the diagnosis

of treatable rhythms, meaning that lay responders or bystanders are able to use them successfully

with little, or in some cases no training at all.

In 1959 Bernard Lown commenced research into an alternative

technique which involved charging of a bank of capacitors to

approximately 1000 volts with an energy content of 100-200

joules then delivering the charge through an inductance such as

to produce a heavily damped sinusoidal wave of finite duration (~5 milliseconds) to the heart by way of

'paddle' electrodes. The work of Lown was taken to clinical application by engineer Barouh Berkovits

with his "cardioverter".

The Lown waveform, as it was known, was the standard for defibrillation until the late 1980s when

numerous studies showed that a biphasic truncated waveform (BTE) was equally efficacious while

requiring the delivery of lower levels of energy to produce defibrillation. A side effect was a significant

reduction in weight of the machine. The BTE waveform, combined with automatic measurement of

transthoracic impedance is the basis for modern defibrillators.

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2.5 Dialysis

In medicine, dialysis (from Greek "dialusis",

meaning dissolution, "dia", meaning through, and

"lysis", meaning loosening) is primarily used to

provide an artificial replacement for lost kidney

function (renal replacement therapy) due to renal

failure. Dialysis may be used for very sick patients

who have suddenly but temporarily, lost their kidney

function (acute renal failure) or for quite stable patients who have permanently lost their kidney

function (stage 5 chronic kidney disease). When healthy, the kidneys maintain the body's internal

equilibrium of water and minerals (sodium, potassium, chloride, calcium, phosphorus, magnesium,

sulfate). Those acidic metabolism end products that the body cannot get rid of via respiration are also

excreted through the kidneys. The kidneys also function as a part of the endocrine system producing

erythropoietin and 1,25-dihydroxycholecalciferol (calcitriol). Dialysis is an imperfect treatment to

replace kidney function because it does not correct the endocrine functions of the kidney. Dialysis

treatments replace some of these functions through diffusion (waste removal) and ultrafiltration (fluid

removal).

Blood flows by one side of a semi-permeable membrane, and a dialysate or fluid flows by the opposite

side. Smaller solutes and fluid pass through the membrane. The blood flows in one direction and the

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dialysate flows in the opposite. The counter-current flow of the blood and dialysate maximizes the

concentration gradient of solutes between the blood and dialysate, which helps to remove more urea

and creatinine from the blood.

There are two primary types of dialysis, hemodialysis and peritoneal dialysis, and a third

investigational type, intestinal dialysis.

2.5.1 Hemodialysis

In hemodialysis, the patient's blood is pumped through the blood compartment of a dialyzer, exposing

it to a partially permeable membrane. The cleansed blood is then returned via the circuit back to the

body. Ultrafiltration occurs by increasing the hydrostatic pressure across the dialyzer membrane. This

usually is done by applying a negative pressure to the dialysate compartment of the dialyzer. This

pressure gradient causes water and dissolved solutes to move from blood to dialysate, and allows the

removal of several litres of excess fluid during a typical 3 to 5 hour treatment. In the US, hemodialysis

treatments are typically given in a dialysis center three times per week (due in the US to Medicare

reimbursement rules); however, as of 2007 over 2,500 people in the US are dialyzing at home more

frequently for various treatment lengths.[2] Studies have demonstrated the clinical benefits of dialyzing

5 to 7 times a week, for 6 to 8 hours. These frequent long treatments are often done at home, while

sleeping but home dialysis is a flexible modality and schedules can be changed day to day, week to

week. In general, studies have shown that both increased treatment length and frequency are clinically

beneficial.[3]

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2.5.2 Peritoneal dialysis

In peritoneal dialysis, a sterile solution containing minerals and glucose is run through a tube into the

peritoneal cavity, the abdominal body cavity around the intestine, where the peritoneal membrane acts

as a semipermeable membrane. The dialysate is left there for a period of time to absorb waste

products, and then it is drained out through the tube and discarded. This cycle or "exchange" is

normally repeated 4-5 times during the day, (sometimes more often overnight with an automated

system). Ultrafiltration occurs via osmosis; the dialysis solution used contains a high concentration of

glucose, and the resulting osmotic pressure causes fluid to move from the blood into the dialysate. As

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a result, more fluid is drained than was instilled. Peritoneal dialysis is less efficient than hemodialysis,

but because it is carried out for a longer period of time the net effect in terms of removal of waste

products and of salt and water are similar to hemodialysis. Peritoneal dialysis is carried out at home by

the patient. Although support is helpful, it is not essential. It does free patients from the routine of

having to go to a dialysis clinic on a fixed schedule multiple times per week, and it can be done while

travelling with a minimum of specialized equipment.

2.6 Medical monitoring

A medical monitor is an automated medical

electronic device that measures a patient's

vital signs and displays the data so obtained,

which may or may not be transmitted on a

monitoring network.

Monitors may be classified as

1. Handheld

2. Portable

3. Tabletop

4. Networkable / non-networkable

5. Mains powered or mains + battery

powered

In critical care units of hospitals, it allows

continuous monitoring of a patient, with

medical staff being continuously informed of

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the changes in general condition of a patient.

Old patient monitors resembled oscilloscopes and computer monitors and use superficially similar

technology. However, medical monitors have been safety engineered so that failures are either

apparent or unimportant.

Some monitors (for example ECG and EEG) have an electrical contact with the patient. There are

strict limits on how much current and voltage can be applied, even if the unit fails or becomes wet.

They must typically withstand electrical defibrillation without damage.

In the past, medical monitors tended to be highly specialized. One monitor would track a patient's

blood pressure, while another would measure pulse oximetry. Today the trend is toward multi-

parameter monitors that can track many different vital signs at once.

2.7 Intravenous therapy

Intravenous therapy or IV therapy is the giving

of liquid substances directly into a vein. It can be

intermittent or continuous; continuous

administration is called an intravenous drip. The

word intravenous simply means "within a vein",

but is most commonly used to refer to IV therapy.

Therapies administered intravenously are often

called specialty pharmaceuticals.

Compared with other routes of administration, the

intravenous route is the fastest ways to deliver

fluids and medications throughout the body.

Some medications, as well as blood transfusions

and lethal injections, can only be given

intravenously.

2.8 Nanogastric intubation

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Nasogastric intubation is a medical process involving the insertion of a plastic tube (nasogastric tube, NG tube) through the nose, past the throat, and down into the stomach.

The main use of a nasogastric tube is for feeding and for

administering drugs and other oral agents such as

activated charcoal. For drugs and for minimal quantities of

liquid, a syringe is used for injection into the tube. For

continuous feeding, a gravity based system is employed,

with the solution placed higher than the patient's stomach.

If accrued supervision is required for the feeding, the tube

is often connected to an electronic pump which can control

and measure the patient's intake and signal any

interruption in the feeding.

2.9 Pulse oximetry

Pulse oximetry is a non-invasive method allowing the monitoring of the oxygenation of a patient's

hemoglobin.

A sensor is placed on a thin part of the patient's anatomy,

usually a fingertip or earlobe, or in the case of a neonate,

across a foot, and a light containing both red and infrared

wavelengths is passed from one side to the other. Changing

absorbance of each of the two wavelengths is measured,

allowing determination of the absorbances due to the pulsing

arteria blood alone, excluding venous blood, skin, bone,

muscle, fat, and (in most cases) fingernail polish.[1] Based

upon the ratio of changing absorbance of the red and

infrared light caused by the difference in color between

oxygen-bound (bright red) and oxygen unbound (dark red or blue, in severe cases) blood hemoglobin,

a measure of oxygenation (the per cent of hemoglobin molecules bound with oxygen molecules) can

be made.

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