Dr Shanthi Vijayaraghavan

Professor , Gastroenterology , SriRamachandra University

Consultant gastroenterologist , Lifeline Hospitals , OMR

Overview Endoscopy and new techniques Lasers Diathermy Electrical safety

ENDOSCOPY

Endo inside

Scopy examination of

Endoscopy looking inside

PRINCIPLES OF ENDOSCOPY In all flexible endoscopic system light is

transmitted down the endoscope shaft to illuminate the surface to be examined.

The reflected image is conveyed back to the endoscopist via one of two different modalities

A. Fiber optics

B. Electronics

Fiber optic Endoscopy

a fixed lens at the end of the instrument shaft focuses the image on internal fiber optic bundle.

The bundle is 2-3mm wide &has20,000-40,000 fine glass fibers, each approx 10mm dia.

The image undergoes a series of internal

reflection with in each fiber as it is transmitted up the bundle.

Electronic Endoscopy

Most endoscopes currently are electronic.

image is reflected onto a charge coupled device [CCD] chip mounted on the end of instrument

chips contain 100,000 to 300,000 pixels.

1 Function buttons, e.g., video recorder remote control 2 Freeze button 3 Suction button 4 Air/water button 5 Instrument channel 6 Locking device 7 Angling wheel (right/left) 8 Angling wheel (up/down)

Tip of Endoscope

Video processor (above) and light source (below)

Gastrointestinal Endoscopy

Types of Gastrointestinal Endoscopy

Upper GI Endoscopy

Colonoscopy (Lower GI Endoscopy)

Small Bowel Enteroscopy

Endoscopic Retrograde Cholangiopancreatogram (ERCP)

Capsule Endoscopy

Capsule Endoscopy

Endoscopic Ultrasound The ultrasound probe is

placed at the tip of the scope

Allows ultrasonography of organs from a close distance

Individual layers of the GI wall are visualized as distinct layers

Magnification Endoscopy

Principle. Magnification endoscopy, known also as zoom endoscopy, can be used for the detailed endoscopic evaluation of suspicious areas, especially after staining

Virtual Endoscopy steps:

3D imaging of the organ of interest (e.g using CT, MRI)

3D preprocessing

3D image analysis

Virtual Endoscopy Features Advantages:

there are no restrictions on the movement of

virtual endoscope (it can be moved anywhere

through the body)

avoids insertion of an instrument into a natural

body opening or minimally invasive opening

no hospitalization

Disadvantage:

current virtual endoscopy techniques do not

reveal the look of the tissue surface (3D

imaging techniques do not reveal

Latest trend is throw-away endoscopes that feature a miniaturized sensor and downstream video-processing circuitry

Delivery systems

Free beam

Optical fiber

Articulated arm

Lens

Selected Applications of Lasers in Medicine Diagnostic: Goal is to learn something about the tissue Therapeutic: Goal is to modify the tissue, e.g. kill malignant cells.

Lasers in medicine: blood and blood flow in the tissues

Where do we use lasers? (some examples)

destruction ...

treatment (eg. photodynamic therapy in cancer) surgery - the CO2 laser scalpel - removal of lens in cataract surgery of the eye

- caurtery of blood vessels in the retina

- welding of detached retina

imaging ...

skin blood flow (Laser Doppler Flow-mapping) curvature of the front of the eye (corneal topography) blood vessels and nerves of the retina - OCT (optical coherence tomography)

- SLO (scanning laser ophthalmoscope)

laboratory diagnostics ...

blood sample analysis microscopy of tissue samples

APC laser coagulation

Electrosurgical/Surgical Diathermy Units

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Electrolysis (mainly near d.c.)

Neuromuscular effects (mainly 10-100Hz)

Heating (mainly 100KHz-30Mhz)

Physiological Effects of Electricity on the Body

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For a (15-100Hz) current passing between the hands, the following effects are expected:

0.5-1mA Perception

10mA Cant let go

100mA Severe pain. Interference with breathing and heart function

1A Sustained heart contraction

Neuromuscular Effects

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Macroshock:

Large current passing through the skin - a small proportion may pass through the heart

Microshock:

Current applied directly to the heart (e.g. pacing leads, intracardiac temperature/pressure lines).

Neuromuscular Effects

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Na+ Na+ Na+

Cl- Cl- Cl-

_ +

Sodium atoms

created at electrode Chlorine atoms

created at electrode

Ionic Current

The formation of sodium atoms at the negative electrode and

chlorine atoms at the positive electrode causes local chemical

actions which kills the cells.

Electrolysis

Physiological Effects of Electricity

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Some Basic Electrosurgery Facts

Used in about 80% of all surgical procedures

Very effective surgical tool Cutting

Coagulation

Fulguration

Basic Principles of Electrosurgery

Current conducted through a complete circuit including the generator, insulated cables, electrodes, and the patient

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Monopolar Electrosurgery

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Bipolar Electrosurgery

Electrosurgical

Unit

Tissue between

tips of forceps

Current

Flow

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Electrosurgery Safety Features

Continuity Monitor

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Electrosurgery Safety Features

Continuity Monitor Verifies that a return electrode is

connected to electrosurgical unit

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Electrosurgery Safety Features

Return Electrode Contact Quality Monitor (RECQM)

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Electrosurgery Safety Features

Return Electrode Contact Quality Monitor (RECQM)

Offers better level of protection than

continuity monitor

Assures that good contact exists between the dispersive electrode and patient

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Dual Plate Return Electrodes

Interrogation current flows

between each plate of the

electrode and the patient. If

one side is partially detached

from the patient, an alarm

will sound.

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Electrosurgical Accidents Skin Burns

Fires, Explosions Prepping Solutions, Surgical Drapes,

Bowel Gas

Oxygen-Enriched Atmosphere

Active Electrode Arc or Spark

Too Much/Too Little Power Delivered

Organ Perforations

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A Misconnection Problem

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Electrosurgical Accidents

Argon Beam Coagulators Gas Embolism

Interference

User Injuries Hand sensation

Alternate pathways

Active Electrode Accidents Inadvertent activation of the ESU due

to unintentional switch activation User places active electrode on the patient or

the surgical drape between intended activations

Safety holster not used Audible activation tone volume is set too low

Insulation failure along shaft during procedures, such as tonsillectomy causing burn to tissue inside mouth or to lip

User makes direct contact with nontarget tissue

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Electrosurgical Injuries Return Electrode

Poor Site Preparation

Poor Application technique

Non-uniform Conductivity

Repositioning Patient

Electrode

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Laparoscopic Electrosurgery

Monopolar vs. Bipolar

Current leakage though cannula

Insulation breakage

Fire

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ESU-caused Fires

Heat, sparks, flaming gases

Rarely a device failure a known complication

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Diathermy

Application of High-Frequency Electromagnetic Energy

Used To Generate Heat In Body Tissues

Heat Produced By Resistance of Tissues

Also Used For Non-Thermal Effects

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Heating Effects - Surgical Diathermy

In Surgical Diathermy the heat is concentrated at the tip of the

probe because the current density (A/m2) is very high but at the

plate it is low. Heating will occur at the plate if the contact area

reduces (plate comes loose)

Skin Internal Skin

Current = I

Low

current

density at

return

electrode

Current = I

Very high

current density

at active

electrode

Shortwave Diathermy A deep-heating modiality Uses energy that is similar to broadcast

radio waves but has a shorter wave length

The energy is delivered to the body is acutally a high-frequency alternating current, but lacks the properties needed to depolarize motor or sensory nerves.

The Federal communication Commission has reserved the frequencies of 13.56, 27.12, and 40.61 for medical use

.

2 units that are commonly used The condenser unit

The conduction unit

Condenser unit patient within the actual circuit of the

machines unit 2 insulated plates are place on either side of

the site being treated The flow of electromagnetic energy passes

through the tissues, which act as electrical resistors and produce frictional heating

Heating occurs at depths of 2.5-5 cm but is uneven because of differences in the resistance to energy transportation of various tissues

Induction Unit

Does not place the patient directly in the units circuit.

Tissues are affected by radiation emitted form the electromagnetic field created by the electrode

may heat tissues up to 5cm beneath the skin

ELECTRICAL SAFETY

Hospital Safety

Human susceptibility to electric shock varies & depends on general state of health

position of any electrodes on the patient

dampness of skin

Safety Standards

Equipment is designed & built to comply with safety standards, namely BS EN 60601-1

This lays down constructional guidelines for medical equipment which influence the safety of the equipment

Safety Testing To BS EN 60601-1

Medical electrical equipment is divided into two classes Class 1

Class 2

And, three types Type B

Type BF

Type CF

Leakage Current & Loss of Grounding

MA

INS

PA

RT

AP

PL

IED

PA

RT

M

P

Class 1

A serious hazard due to the simple failure of basic insulation or the loss of ground lead will then produce a deadly situation of the metal case /equipment being at live mains voltage which may flow through the patient.

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Connecting Medical with Non-Medical Equipment

IEC 60601 IEC XXXXX A/P

Functional

Connection

The medical equipment might draw large currents via the I/O portMake sure the I/O port is isolated from the enclosure and the A/P. If it is not or if unsure use an separation device

Electrical Hazards

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N/C

N/

C

Ferrite

Ring

RCD circuit

L

N

I

live

I

Neutral

These sense the difference between currents in the live and neutral leads. If the difference exceed a set level a relay is operated to disconnect the supply

Residual Current Devices (RCDs)

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Electrical Hazards

Incidents of Electrocution in Hospitals

Humidity in the plugs of blood and fluid heaters causing

device failure (Andersen C, Pold R, Nielsen HD. Ugeskr Laeger 2000; 162(6))

Accidental toppling of a fluid container causing spillage onto a

blood pressure monitor (Singleton RJ, Ludbrook GL, Webb RK, Fox MA. Anaesth Intensive Care 1993; 21(5))

Electric shocks to anaesthetists after touching a faulty device

and the chassis of another device simultaneously (Singleton RJ, Ludbrook GL, Webb RK, Fox MA. Anaesth Intensive Care 1993; 21(5))

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Electrical Safety Testing Procedure

Visual Inspection

Earth Resistance

Insulation

Leakage Current

Earth Leakage

Current Touch Current Patient Leakage

Current

Electrical Safety Testing

Changed roles

Surgeons become computerized

Engineers, mathematicians and physicists enter the hospitals

Thank you