3. In biological and chemical research, solutions are often
quantified by measuring their degree of light absorption at
a particular wavelength. A value called the extinction
coefficient is used to calculate the concentration of the
compound. Molecular biology laboratories use
spectrophotometers to measure the concentrations
of DNA or RNA samples..
Microbiological and molecular biology laboratories
frequently use a spectrophotometer to measure the growth
of cultures of bacteria. DNA cloning experiments are often
done in bacteria, and researchers need to measure the
growth stage of the culture to know when to carry out
certain procedures. They measure the absorbance, which is
known as the optical density (OD), on a spectrophotometer
4. • Background
• Beer-Lambert law
• The Spectrophotometer
• Basic components
• Types of Spectrophotometers
• Operation
• Maintenance
• Applications of Spectrophotometer
CONTENTS:-
5. Spectroscopy is the study of the interaction between electromagnetic radiation
and matter
Each type of spectroscopy gives a different picture of the matter →the spectrum
The spectrum is the variation of the intensity of the radiation as a function of the
frequency or wavelength
Intensity : energy crossing unit area per second
are the permittivity and permeability of a vacuum medium. E0
and B0 are the maximum amplitude of the electric and magnetic waves
Historically, the electromagnetic radiation has been divided into various regions
extending for different frequency or wavelength intervals
From the spectroscopic point of view, these regions may be associated to
different properties and to different motions of molecules
6.
7.
8. Radiant energy may be defined as energy, the propagation
and transfer of which takes place as a wave motion
without transfer of matter. The term, radiant energy, is
generally used with reference to electromagnetic radiation
9. Introduction :
At natural state, most of the atoms, molecules and electrons are in the lowest
energy level called ground state.
To transits from lower energy level to highest the electron need promotion
“as light” and its called energy transition.
When a chemical absorbs light, it goes from a low energy state (ground state)
to a higher energy state (excited state)
Only photons with energies exactly equal to the energy difference between
the two electron states will be absorbed
Since different chemicals have different electron shells which are filled, they
will each absorb their own particular type of light
10. When transitions occurs, the wavelength and energy
decreases, and increases of frequency.
The Light waves consist of perpendicular, oscillating
electric and magnetic fields ” Electro- magnetic
waves” and described by
1. amplitude(A),
2. wavelength(λ),
3. frequency(F).
For the light the freq. increases, energy increases and
wavelength decreases through
Introduction :
E = h = h
C
C
=
C =
11. • Visible light is only a small
portion of the entire
electromagnetic spectrum
• it includes the colors
commonly observed (red,
yellow, green, blue and
violet).
• The visible spectrum
consists of electro-
magnetic radiation whose
wavelengths range from
380nm to nearly 760nm.
Introduction :
12. (nm) Region Color Observed
< 380 Ultraviolet Not visible
380-440 Visible Violet
440-500 Visible Blue
500-580 Visible Green
580-600 Visible Yellow
600-620 Visible Orange
620-750 Visible Red
750-2000 Short IR Not visible
Introduction :
13.
14.
15.
16.
17.
18. Lambert’s Law of Absorption:
• Lambert described how intensity changes with distance in an
absorbing medium.
• The intensity I0 of light beam decreases exponentially as it
passes though a uniform absorbing medium.
I=IO10-ebc c is the concentration, b is the path length, e is the
extinction coefficient
source I detector
Beer-Lambert law:
19. Beer’s Law
The intensity of a ray of monochromatic light
decreases exponentially as the concentration
of the absorbing medium increases.
More dissolved substance = more absorption
and less transmittance
20. • Photometric Quantities
• In photometry we measure the intensity of light and characterize its change
by substance.
• This change is typically expresses as percent transmittance or absorbance.
Transmittance (T)
Absorbance (A)
0
I
I
T
T
I
I
A log
log
0
usually given in percent
by convention, base 10 logs are used
Beer-Lambert law:
21. Absorbance and the extinction coefficient
• Absorbance is useful since it can be summed for
layers of different materials
A = A + A + A + …
A = ε C b + ε C b + ε C b + …
A specialized device to measure the intensity of
light as a function of wavelength is the
spectrophotometer.
tot 1 2 3
tot 1
1 1 2 2 2 3 3 3
22. one of the basic medical laboratory
instruments uses to measure light intensity as
a function of wave length(λ).
Measures absorbance as a function of
wavelength
The device important
for determining the
unknown substances
and for calculating
the concentration of
known substances. The Camspec M550 Double Beam Scanning UV/Vis Spectrophotometer
The Spectrophotometer
26. Basic components:
1- Light Source: provides the light to be passed
through the sample.
a source must generate a beam of radiation
that is sufficiently powerful for easy detection
and measurement.
- Hollow Cathode Lamps (HCL)
- tungsten Lamp: visible light .
- Hydrogen discharge: ultraviolet Light.
its output power should be stable for reasonable periods.
27. 2- monochromator: used to select a given wavelength of
the light from the light source.
mono single.
chroma color.
ator denoting an agent
There exists many techniques for that
• Diffraction gratings
• Prisms
• Collimation
• Stray light
• Wavelength range
• Double monochromator
Basic components:
28. 2- monochromator:
• Diffraction gratings
To obtain of specific wavelength:
1. entrance slit.
2. concave mirror or lens.
3. a prism or grating.
4. focal plane.
5. exit slit.
Basic components:
29. 2- monochromator:
• Prisms spray out the spectrum and choose the certain wavelength
that you want by slit.
Basic components:
30.
31. 3- Sample Cell:
• A container that contains a sample is usually called
"cell"
• has fixed length & volume.
• usually round or square cuvette.
• made of material that does not absorb light in the
wavelength range.
• two types are available:-
- Glass – visible region.
- Quartz – ultraviolet.
Basic components:
32. 4- Detector:
• to convert the radiant energy to a measurable
signal; and to a readout device
• “Detector” is a device that indicates the
existence of some physical phenomenon.
• The term transducer is used to indicate the
type of detector that converts quantities, such
as light intensity, into such electrical signals
that can be subsequently amplified,
manipulated, and finally converted into
numbers.
Basic components:
33. Basic components:
Ideal detector : high sensitivity.
high signal/noise.
fast response time.
constant response for λs.
responds to low levels of energy.
94. Holter Monitoring
A Holter monitor is a small,
wearable device that keeps track
of your heart rhythm.
OR, a Holter monitor is a small
recorder that makes a nonstop
electrocardiogram (e-LECK-tro-
KAR-dee-o-gram) or EKG of the
heart over a full 24-hour period.
The EKG measures the electrical
beats of the heart.
95. A Holter monitor uses
electrodes and recording device
to track your hearts rhythm for
24 to 72 hours.
Holter Monitor testing is also
sometimes called ambulatory
electrocardiography.
It can recognise abnormal
heartbeats during normal
activities, exercise and sleep.
97. How it works
The Holter monitor is small. It slightly larger
than a deck of playing cards.
This device is worn around your neck or on
your belt.
Several leads and wires are attached to the
monitor.
The leads connect to electrodes that are
placed on the skin of your chest with a glue
like gel.
The metal electrodes conducts hearts
activity through the wires and in to the
Holter monitor, where it is recorded
98.
99. Result Of Holter Monitor
The information from Holter monitor
may reveals that you have a heart
condition, or your doctor may need
more tests to find out what may be
causing your symptoms.
If your doctor may not able to diagnose,
then he/she will recommend a wireless
Holter monitor or an event recorder,
both of which can be worn longer than
a standard Holter monitor.
100. Key things to remember
The cable, connected leads, and
patches must remain attached the
whole time. If a patch comes off,
clean the area and put back on. You
will have extra patches.
Do not get the monitor, cable, leads
or patches wet. Do not swim, take a
bath, or shower while wearing the
monitor.
Try to sleep on your back, with
the recorder at your side. This
will keep the patches from being
pulled off.
Avoid electric blankets,
magnets, metal detectors, and
high voltage areas such as
power lines. Signals from such
devices may affect the data.
101. Evoked Potentials
Evoked potentials are electrical signals that are generated by the
nervous system in response to a stimulus and are event-related (i.e.,
evoked by the onset of stimulus).
With evoked potentials, it could be a number of stimuli (e.g., visual,
auditory, sensory stimuli).
The selection of presentation stimuli is dependent on what type of
evoked potential you are performing.
Evoked potentials are useful in diagnosing a variety of neurological
disorders.
102. Auditory evoked potentials (AEP):-
A diagnostic tool to determine the integrity of the auditory system and make
inferences about hearing.
AEPs is not a hearing test but it is a tool to predict hearing.
With auditory evoked potentials an acoustic stimulus generates a response
measured using skin electrodes on the surface of the skin.
The stimulus that is being generated is minimal thus we have to use gain and
amplify to measure the response.
It also objectively tests the integrity of the hearing system from the level of the
cochlea to the brainstem.
103. Visual Evoked Potential:-
The visual evoked potential (VEP) tests the function of the visual pathway from
the retina to the occipital cortex.
It measures the conduction of the visual pathways from the optic nerve, optic
chiasm, and optic radiations to the occipital cortex.
VEPs are most useful for testing optic nerve function and less useful for
assessing postchiasmatic disorders.
VEP is clearly more sensitive than physical examination in detecting optic
neuritis.
The usual VEPs are evoked by checkerboard stimulation.
Because the cells of the visual cortex are maximally sensitive to movement at
the edges, a pattern-shift method is used, with a frequency of 1-2 Hz.
104. With an abnormal VEP, the differential diagnostic
considerations include the following:
Leber hereditary optic
neuropathy
Aluminum neurotoxicity
Manganese intoxication
Retrobulbar neuritis
Ischemic optic neuropathy
Tumors compressing the optic
nerve
Optic neuropathy
Optic neuritis
Ocular hypertension
Glaucoma
Diabetes
Toxic amblyopia
105. Magneto Encephalograph
• Magnetoencephalography (MEG) is a functional neuroimaging technique for
mapping brain activity by recording magnetic fields produced by electrical
currents occurring naturally in the brain, using very sensitive
magnetometers.
• Arrays of SQUIDs (superconducting quantum unit interference devices) are
currently the most common magnetometer, while the SERF (spin exchange
relaxation-free) magnetometer is being investigated for future machines.
• Applications of MEG include basic research into perceptual and cognitive
brain processes, localizing regions affected by pathology before surgical
removal, determining the function of various parts of the brain, and
neurofeedback.
106. Myoelectric Control
The myoelectric control system uses myoelectric signals to generate control
commands that can be used to control several kinds of devices.
A myoelectric signal is an electric biological signal generated by the motor
neurons connected to the muscle fibers during the contraction of a muscle.
To measure these signals so as to use them in the control system, an
electromyography (EMG) circuit has been designed.
The EMG circuit detects the signal with two electrodes, and then it filters and
amplifies the signal.
107. The basic functional unit in the neural control of the muscular contraction pro-
cess is the motor unit. It is composed of an α-motoneuron and all the muscle
fibers that are innervated by the multiple branches of the motor neuron’s axon.
When the motoneuron activates its associated muscle fibers, a small electric
signal is generated: the motor unit action potential (MUAP).
This signal is the fundamental component of the myoelectric signal.
The use of electrodes is necessary to measure the myoelectric signal.
The two main types of electrodes are used to detect the myoelectric signal are:
invasive and non invasive
108. • Invasive electrodes:-measure the myoelectric signals directly from the user’s
nervous system, using needle or wire electrodes implanted into the muscles.
• This kind of electrodes deliver high quality signals because they are gathered
exactly from the right spot and they are very little affected by noise.
• The small detection area allows the detection of individual MUAPs during low force
contractions.
• The use of needle electrodes is painful, because they consist of a cannula with one
or more wires inside, and the cannula must remain inside the muscle throughout
the duration of the measurements.
• Wire electrodes are less painful as they have a diameter of 25-100µV and the
cannula is only used to insert them into the muscle.
• The maintenance of these electrodes is very delicate, and their invasive nature
makes them not suitable for their use in the control of myoelectric prostheses.
• Invasive electrodes are used in exploratory clinical EMG, in kinesiological and
neurophysiological studies of deep muscles ,to study MUAP characteristics, or to
study control properties of motor units.
109. Non-invasive electrodes:- are also called surface electrodes, because the
myoelectric signal is measured on the surface of the skin
For this reason, it is impossible to measure individual MUAPs; the measured
signal is the sum of all MUAPTs generated under the electrodes.
Are easier to use and maintain and they do not require painful procedures to be
used.
Surface electrodes are classified in two categories: passive andactive electrodes
110. Surface electrodes have some disadvantages:
Non-selective detection of the signal: as said before, surface electrodes can be used
effectively only with superficial muscles and they cannot be used to detect signals
selectively from small muscles.
Physiological cross-talk: as the detection area covers all the underlying muscles, those
muscles in the vicinity of the muscle of interest may produce myoelectric signals that are
also detected by the electrodes. This phenomenon is known as ”cross-talk”.
Electrical noise: the signal acquired by non invasive electrodes has to be filtered and
conditioned because, being measured on the surface of the skin, it is much more affected
by different kinds of electric noise.
Tissue characteristics: the electrical conductivity of the human body varies with tissue
type, thickness of the subcutaneous fat tissue, physiological changes, sweat and
temperature.
Changes between the muscle belly and electrode site: the myoelectricsignal changes with
the variation of the distance between signal origin anddetection site. This variation may
be caused by dynamic contractions or byexternal pressure
111. • Unlike invasive electrodes, surface electrodes are used to interface a person with an external
device, for example an electrically powered prosthesis.
• Myoelectric signal as control signal is so broadly used in the field of prosthetic devices
because it has some advantages over other control signals.
• The user is freed of straps and harnesses
• The signal is noninvasively detected on the surface of the skin
• the muscle activity which provides the control signal is relatively small
and can resemble the effort required from an intact limb.
• The signal can be adapted for proportional speed or force control in a
relatively simple way
• The electronic circuits that acquire, filter and process the signal can be
continuously improved and miniaturized, allowing the design of less
bulky, lighter and more aesthetic devices
• And with the increasing speed of microprocessors , more complex
algorithms that allow the prosthesis to perform more complex functions
can be used.
112. Myoelectric control systems:-
To control a device with a myoelectric signal, the signal has to be processed in
order to extract those features that are useful to perform the control.
The raw myoelectric signal is not suitable as a control signal, but several of its
features can be used as control inputs.
The system that extracts the features of the signal and uses them to generate the
control commands for the device is called myoelectric control system, or MCS.
In the field of prosthetic devices, the MCS uses myoelectric signals from the
amputee’s remaining limb muscles to control the different movements and actions
of the prosthesis.
Usually, the myoelectric signal is acquired in a non invasive way, by using surface
electrodes.
The valuable information of the muscle contractions provided by the signal is used
by the MCS to send commands to the active prosthesis to perform movements.
113. • There are other examples of the use of myoelectric control in various
applications such as wheelchair control , exoskeleton control or grasping
control .
• Myoelectric control systems can be classified in two groups: pattern
recognition and non-pattern recognition-based.
• In the latter group, the controllers are mainly constructed on threshold control
and/or finite state machines, and their output are limited and predefined
control commands based on a sequence of input signal patterns.
• Pattern recognition-based controllers are more com-plex: they are able to
discriminate the desired classes of functions from signal patterns, using
classifiers.
115. Medical uses
• Electrotherapy machines are a popular modalities used in physical therapy
and rehabilitation.
» Relaxation of muscle spasms
» Prevention and cessation of muscular atrophy due to disuse
» Improved local blood circulation and flow
» Re-education of muscles using targeted stimulation
» Preserve and improve range of motion
» Management and reduction of pain (chronic, post-traumatic,
and post-surgical acute)
» Prevention of deep vein thrombosis post-surgery
» Facilitation of wound healing
» Improvement in the effectiveness in delivering prescription
drugs-electromotive drug administration (EMDA)
231. What is It ?
• A medical equipment that provides
Cardiopulmonary bypass, (temporary
mechanical circulatory support) to the
stationary heart and lungs)
• Heart and Lungs are made “functionless
temporarily” , in order to perform surgeries
• CABG
• Valve repair
• Aneurysm
• Septal Defects
232. History
• Lewis and Taufic first used the Hypothermia
Approach clinically on September 2, 1952.
Under moderate total body hypothermia,
Lewis and Taufic used a short period of
circulatory arrest to repair a congenital defect
in a 5 year-old girl.
• An alternative approach named Cross-
Circulation was used by Dr. C. Walt when on
March 26, 1954,when he repaired a VSD in a
12 month-old infant.
233. • On May 6, 1953, Dr. Gibbon used his heart–
lung machine to successfully repair an atrial
septal defect in an 18 year-old girl,
• Marking the first successful clinical use of a
Heart–Lung Machine
237. Principles and Necessity
Heart is Stopped
Blood diverted through
tubes and is pumped
to maintain flow
Temperature regulation of blood
and gaseous exchange is done
Blood circulated systemically
bypassing the heart
and lungs
238.
239.
240.
241. Cardioplegia
• The intentional and temporary cessation of cardiac
activity.
• Common procedure for accomplishing asystole is infusing
cold crystalloid cardioplegia into the coronary circulation.
Iced (4 degrees Celsius) solution of dextrose, potassium
chloride, and Magnesium rich solution is introduced via
specialized Cannula.
• B05XA16
• MeSH
242. Parts
• Five pump assemblies
• Venous Cannula
• Arterial Cannula - dual-stream aortic perfusion catheter /
meshed cannula
• Venous Reservoir
• Oxygenators
• Heat Exchangers
• Cardiotomy Reservoir and Field Suction
• Filters and Bubble Traps
• Tubing and Connectors
243.
244. Pumps
• Centrifugal pumps consist of plastic cones,
which when rotated rapidly, propel blood by
centrifugal force.
• Forward blood flow, varies with the speed of
rotation and the after load of the arterial line.
• Centrifugal blood pumps generate up to 900
mm Hg of forward pressure, but only 400 to
500 mm Hg of negative pressure. Hence, less
gaseous micro emboli.
• Centrifugal pumps produce pulse less blood
flow
Centrifugal
Roller
245. • Roller pumps consist tubing, which is
compressed by two rollers 180° apart.
Forward flow is generated by roller
compression and flow rate depends upon the
diameter of the tubing, rate of rotation.
247. Five pump assemblies :
• A centrifugal or roller head pump can be used in the
arterial position for extracorporeal circulation of the
blood.
• Left ventricular blood return is accomplished by roller
pump, drawing blood away from the heart.
• Surgical suction created by the roller pump removes
accumulated fluid from the general surgical field.
• The cardioplegia delivery pump.
• Emergency Backup of the arterial pump in case of
mechanical failure.
248. Venous Reservoirs
• Reservoirs may be rigid (hard) plastic canisters ("open"
types) or soft, collapsible plastic bags ("closed" types).
• The venous reservoir serves as volume reservoir
• Facilitates gravity drainage,
• Venous bubble trap present,
• Provides a convenient place to add drugs, fluids, or
blood, and adds storage capacity for the perfusion
system.
250. Membranous Oxygenators
• Imitate the natural lung by interspersing a thin
membrane of either micro porous
polypropylene or silicone rubber between the
gas and blood phases.
• With micro porous membranes, plasma-filled
pores prevent gas entering blood but facilitate
transfer of both oxygen and CO2.
• The most popular design uses sheaves of
hollow fibers connected to inlet and outlet
manifolds within a hard-shell jacket.
251. Bubble Oxygenators
• Venous blood drains directly into a chamber into which
oxygen is infused through a diffusion plate (sparger).
• The sparger produces thousands of small (approximately
36 µm) oxygen bubbles within blood.
• Gas exchange occurs across a thin film at the blood-gas
interface around each bubble
• Produce more particulate and gaseous microemboli are
more reactive to blood elements.
252. Heat Exchangers
• Control body temperature by heating or
cooling blood passing through the perfusion
circuit
• Temperature differences within the body and
perfusion circuit are limited to 5°C to 10°C to
prevent bubble emboli
253. Filters and Bubble Traps
• In the circuit, micro emboli are monitored by
arterial line ultrasound or monitoring screen
filtration pressure.
• Depth filters consist of porous foam, have a
large, wetted surface and remove micro
emboli by impaction and absorption
• Screen filters are usually made of woven
polyester or nylon thread.
254. Tubing
• Medical grade Polyvinyl Chloride (PVC) tubing
• It is flexible, compatible with blood, inert,
nontoxic, smooth, nonwettable, tough,
transparent, resistant to kinking and collapse,
• Can be heat sterilized
• The Duraflo II heparin coating ionically
attaches heparin to a quaternary ammonium
carrier (alkylbenzyl dimethyl - ammonium
chloride), which binds to plastic surfaces.
255. Perfusion Monitors and Sensors
• A low-level sensor with alarms on the venous
reservoir and a bubble detector on the arterial
line are desirable safety devices.
• Flow-through devices are available to
continuously measure blood gases,
hemoglobin/hematocrit , and some
electrolytes
• Temperatures of the water entering heat
exchangers
256. Sterilization :
• Ethylene dioxide is commonly used
• 4 hours of sterilization at 55°C or 18 hours at
22°C .
• Disadvantages of ethylene dioxide , are the
toxicity and explosive nature
• Disposable tubing ,reservoirs and oxgenator
• Steam sterilization as PVC can withstand heat
257. Disadvantages
• Post perfusion Syndrome - a transient
neurocognitive impairment associated with
cardiopulmonary bypass. Some research
shows the incidence is initially decreased by
off-pump coronary artery bypass
260. ENDOSCOPY
C O N T E N T S
• History.
• What is endoscopy?
• Rigid endoscope construction and applications.
• Flexible endoscope construction and applications.
• Endoscope rigid/flexible processing.
• Endoscope rigid/flexible care and maintenance.
• Endoscope rigid/flexible inspection.
• Troubleshooting.
• How to avoid repair.
261. Brief History of Endoscopy
• In the early 1900s, the first attempts to view inside the body
with lighted telescopes were made. These initial devices
were often fully rigid. In the 1930s, semi-flexible endoscopes
called gastroscopes were developed to view inside of the
stomach. Fiber-optic endoscopy was pioneered by South
African-born physician Basil Hirschowitz at the University of
Michigan in 1957. Widespread use of fiber optic endoscopes
began in the 1960s.
• A fiber optic cable is simply a bundle of microscopic glass or
plastic fibers that literally allows light and images to be
transmitted through curved structures.
262. What is Endoscopy?
• Endoscopy is the examination and inspection of the
interior of body organs, joints or cavities through an
endoscope to allows physicians to peer through the
body's passageways.
• An Endoscope is a device using fiber optics and
powerful lens systems to provide lighting and
visualization of the interior of a joint. The portion of
the endoscope inserted into the body may be rigid or
flexible, depending upon the medical procedure.
269. CARE OF RIGID ENDOSCOPE
• Rigid endoscopes must be handled with
care,they are very delicate and can be
damaged easily if dropped or hit againest hard
objects.
• Can be disinfected via gas sterilization or
autoclaved if specified by manufacturer or
soaked in 2-3% glauteraldahyde sol’n mosltly
used safe disinfection technique .
272. The Digestive System
• The digestive tract consists of the followings :
• Mouth
• Throat
• Esophagus
• Stomach
• Duodenum
• Small bowel
• Colon
• Rectum
• Anus
• And other GI organs .
277. GASTROSCOPY
• Upper endoscopy(gastroscopy) enables the physician to look inside the
esophagus, stomach, and duodenum and the first part of the small
intestine. The procedure might be used to discover the reason for
swallowing difficulties, reflux, bleeding, indigestion, abdominal pain, or
chest pain.
• For the procedure you will swallow a thin, flexible, lighted tube called an
endoscope . Right before the procedure the physician will spray your
throat with a numbing agent that may help prevent gagging. You may
also receive pain medicine and a sedative to help you relax during the
exam. The endoscope transmits an image of the inside of the esophagus,
stomach, and duodenum, so the physician can carefully examine the
lining of these organs. The scope also blows air into the stomach; this
expands the folds of tissue and makes it easier for the physician to
examine the stomach.
• Gastroscopy takes around 10 minutes .
279. DUODENOSCOPY(ERCP)
• ERCP combines the use of x rays and an endoscope, which is a
long, flexible, lighted tube. Through it, the physician can see
the inside of the stomach and duodenum, and inject dyes into
the ducts in the biliary tree and pancreas so they can be seen
on x ray .
280.
281. DUODENOSCOPY(ERCP)
Endoscopic retrograde cholangiopancreatography (ERCP)
enables the physician to diagnose problems in the liver,
gallbladder, bile ducts, and pancreas.The liver is a large
organ that, among other things, makes a liquid called bile
that helps with digestion. The gallbladder is a small, pear-
shaped organ that stores bile until it is needed for digestion.
The bile ducts are tubes that carry bile from the liver to the
gallbladder and small intestine. These ducts are sometimes
called the biliary tree. ERCP is used primarily to diagnose
and treat conditions of the bile ducts including gallstones,
inflammatory strictures (scars), leaks(from trauma and
surgery), and cancer.
284. COLONOSCOPY
• Colonoscopy lets the physician look inside the entire large intestine, from the
lowest part, the rectum, all the way up through the colon to the lower end of the
small intestine. The procedure is used to look for early signs of cancer in the colon
and rectum. Colonoscopy enables the physician to see inflamed tissue, abnormal
growths, ulcers, and bleeding.
• If anything abnormal is seen in the colon, like a polyp or inflamed tissue, the
physician can remove all or part of it using tiny instruments passed through the
scope. That tissue (biopsy) is then sent to a lab for testing. If there is bleeding in
the colon, the physician can pass a laser, heater probe, or electrical probe, or
inject special medicines through the scope and use it to stop the bleeding.
• Colonoscopy takes 30 to 60 minutes.
285. SIGMOIDOSCOPY
Flexible sigmoidoscopy enables the physician to look at the
inside of the large intestine from the rectum through the last
part of the colon, called the sigmoid or descending colon.
Physicians may use the procedure to find the cause of
diarrhea, abdominal pain, or constipation. They also use it to
look for early signs of cancer in the descending colon and
rectum. With flexible sigmoidoscopy, the physician can see
bleeding, inflammation, abnormal growths, and ulcers in the
descending colon and rectum. Flexible sigmoidoscopy is not
sufficient to detect polyps or cancer in the ascending or
transverse colon two-thirds of the colon) .
288. BRONCHOSCOPY
• A bronchoscope is a tube with a tiny camera on
the end which is inserted through the nose (or
mouth) into the lungs. During a bronchoscopy
procedure, a scope will be inserted through the
nostril until it passes through the throat into the
trachea and bronchi. A bronchoscope is used to
provide a view of the airways of the lung. The
scope also allows the doctor to collect lung
secretions and lung tissue for biopsy for tissue
specimens.
289.
290. CYSTOSCOPY
• Cystoscopy is a procedure that uses a flexible fiber
optic scope inserted through the urethra into the
urinary bladder. The physician fills the bladder with
water and inspects the interior of the bladder. The
image seen through the cystoscope may also be
viewed on a color monitor and recorded on videotape
for later evaluation.
291.
292.
293. • Endoscopy of the urinary bladder via the urethra
is called cystoscopy.
• Diagnostic cystoscopy is usually carried out with
local anesthesia.
• General anaesthesia is sometimes used for
operative cystoscopic procedures.
294. • The cystoscope has lenses like a telescope or
microscope.
• These lenses let the doctor focus on the inner
surfaces of the urinary tract.
• Some cystoscopes use optical fibres (flexible glass
fibres) that carry an image from the tip of the
instrument to a viewing piece at the other end.
• The cystoscope is as thick as a pencil and has a light
at the tip.
295. • Many cystoscopies have extra tubes to guide
other instruments for surgical procedures to
treat urinary problems.
• There are two main types of cystoscopy
• Flexible Cystoscopy.
• Rigid Cystoscopy.
296. • Flexible cystoscopy is carried out using local
anesthesia on both sexes.
• Typically, lidocaine gel (such as the brand name
Instill gel) is used as an anesthetic, instilled in the
urethra.
• Rigid cystoscopy can be performed under the
same conditions, but is generally carried out under
general anesthesia, particularly in male subjects,
due to the pain caused by the probe.
297. Endoscopy System
• Camera processor
• Monitor
• Light source
• Video recorder
• Video printer
• Suction system
• E.S.U
• Trolley with hanger
• Endoscope
• Endo-accessories
298. FLEXIBLE ENDOSCOPE
The flexible endoscope is a remarkable piece of equipment
that can be directed and moved around the many bends in
the gastrointestinal tract. Endoscopes now come in two
types : The original pure fiberoptic instrument has a
flexible bundle of glass fibers that collect the lighted image
at one end and transfer the image to the eye piece. The
newer video endoscopes have a tiny, optically sensitive
computer chip at the end. Electronic signals are then
transmitted up the scope to computer then displays the
image on a large video screen. An open channel in these
scopes allows other instruments to be passed through in
order to take tissue samples, remove polyps and perform
other exams.
301. • A videoscope is a - usually flexible - endoscope
with an integrated micro-camera.
• Similar to a digital camera, the object is
projected by an objective lens onto a sensor
which produces an electronic image signal.
302. • This signal is transferred in the endoscope via
a thin cable to an evaluation unit in which the
signal is processed and made available as a
standard signal
303. Mechanically:
Flexible videoscopes are mechanically similar to
flexible (optical-fibre) endoscopes.
They consist of a movable tip, a flexible shaft
and a handle. The tip including an objective
lens and a sensor is controlled from the
handle by means of Bowden wires in 2 or 4
directions depending on the design.
304. • The handle may include other control
elements (e.g. remote control for image
storage).
• The illumination of flexible video scopes is
nearly always identical to the one used in
flexible optical-fiber endoscope
• Light is transferred from an external light
source via glass fiber bundles to the tip, where
it emerges.
305. When should videoscopes be preferred to (optical-
fibre) endoscopes?
• Videoscopes provide a resolution of several 100,000
camera pixels, which is significantly higher than in
flexible endoscopes.
• Videoscopes are more light-intensive than a flexible
endoscope combined with a camera.
• Videoscopes can be built with longer lengths too.
• Videoscopes are ideal where several people look at
the picture simultaneously.
307. Control Body
• Houses the following :
o Angulation mechanism
(drives)
o Air/water and suction
valves
o Eye-piece(fiberscopes)
or remote function
buttons(videoscopes).
308. Insertion Tube
• Made of a complex plastic.
• Contains the folllowing:
o LG fiber
o A/W channel
o Biopsy channel
o Angulation wires
o IG fiber or CCD
315. Endoscopic Accessories
• Biopsy forceps
• Graspers
• Baskets
• Injectors
• Dilators
• Knives
• HF endo-therapy
accessories
• . . .And too many types of
accessories.
316. PROCESSING OF ENDOSCOPES
• Mechanical
Cleaning(wiping tubes
and channel brushing in a
detergent sol’n)
• Disinfection
• Rinsing
317. Endoscope Processing Fluids
• Detergent : medical grade,low foaming,neutral PH or
enzymatic with proper dilution and temperature.
• Disinfectant : 2.0-3.0%Glauteraldehyde sol’n(mostly
used and safe HLD).
• Rinsing water : Sterile water is needed to remove
detergent and disinfectant residues,all channels must
be flushed properly then endoscope to be dried by
wiping and then hanged in the special endoscope
cabinet
318. Flexible Care and Maintenance
• Endoscope must be inspected before and after
use for the following :
o Insertion and LG Tubes
o Bending mechanism
o Optical system
o General inspection(apearance)
o Endoscope to be leakage tested
319. Leakage Test
Endoscopes must be checked againest any leak or
damage before use and processing to ensure its
effeciency and avoid instrument malfunction during
endoscopy.
Leakage tester is an instrument which can be attached
to endoscope and blows certain pressure of air-set
by the manufacturer- inside it then endoscope is
immersedin a water basin and checked againest any
leak,if any leak is seen endoscope must be
immediately transferred for repair and must not
been used.
321. Why do air/water problems occur?
• The scope is not cleaned immediately
following procedure.
• Nozzle is damaged, missing or misaligned.
• Severe glutaraldehyde buildup from chemical
disinfectants can break away from the channel
and block the air/water nozzle.
322. How do bending sheaths become damaged?
Any sharp objects, such as instruments, fingernails or
bites can cause tears or holes in the sheath material.
• Over time, normal wear or over inflation can cause
stretching or looseness of the bending rubber
material.
• If the ETO cap is not in place during the ETO gas
sterilization process, the scope will pressurize and
the bending sheath will explode like a balloon. Follow
the instructions on the white card attached to the
ETO cap.
323. How do fluid problems occur?
• If a scope has a leak which is not detected, and the scope
comes in contact with any fluid, moisture will enter the scope
through the leak.
• In fiber scopes, the scope will have major fluid invasion if the
scope is immersed with the ETO venting cap on. For video
scopes, the water proof cap must be attached before contact
with any fluid.
• If a scope has a fluid invasion and is not repaired immediately,
video chip damage and image staining can result, as well as
corrosion of the internal metal components.
• Remember - fluid problems are a scope's worst enemy!
324. Angulation problems are a result of :
• The angulation wires can stretch and break if
the angulation is forced.
• Buckling of the insertion tube can stretch and
break wires.
• Play in the angulation control knobs usually
indicates an angulation adjustment is needed.
325. What causes damage to the channel?
• Kinked, damaged or open flexible biopsy forceps can cause
tears in the channel material.
• Buckling of the insertion tube can cause buckles in the
channel.
• Forcing instrumentation through the channel can cause
wear or tears in the channel material. This frequently occurs
in the bending section when resistance is met while the
scope is angulated. Do not pass anything through the
bending section with the tip angulated further than 110°.
326. How do image and light guide
problems occur?
• Buckles or bites in the insertion or light guide tubes
can break image and light guide fibers.
• Fluid invasion can cause staining of the fibers or
video chip damage if not repaired immediately. The
fluid also causes brittleness of the fiber bundles.
• Pulling on the insertion or light guide tube, as well as
dropping the scope, can cause broken fibers or
damage to the video chip.
327. HOW TO AVOID REPAIR
• Proper handling of endoscope.
• Using recommended accessories correctly.
• Proper processing and using protecting cover in case of
videoscopes.
• Avoid harmful shaking,dropping or hitting againest any
hard object.
• Leakage test before and after use.
• Storing in clean,dry,well ventilated and maintained at
normal temperature.
• FOR ANY QUIRY DON’T TRY TO DISCOVER BY
YOURSELF ASK ABOUT IT. . . . .
366. The closed circuit TV system used in
fluoroscopy.
• At the TV camera (A), an electron beam is swept in raster
fashion on the TV target (e.g., SbS03). The TV target is a
photoconductor, whose electrical resistance is modulated
by varying levels of light intensity. In areas of more light,
more of the electrons in the electron beam pass across the
TV target and reach the signal plate, producing a higher
video signal in those lighter reasons.
367. • The video signal (B) is a voltage versus time
waveform that is communicated electronically by
the cable connecting the video camera with the
video monitor.
• Synchronization pulses are used to synchronize
the raster scan pattern between the TV camera
target and the video monitor.
• Horizontal sync pulses (shown) cause the electron
beam in the monitor to laterally retrace and
prepare for the next scan line.
368. • Inside video monitor(C), the electron beam is
scanned in raster fashion, and the beam
current is modulated by the video signal.
Higher beam current at a given location
results in more light produced at that location
by the monitor phosphor. (0) The raster scan
on the monitor is done in synchrony with the
scan of the TV target
508. • The detector is usually a three or five inch diameter
NaI crystal, situated behind a focusing collimator.
• This is so mounted that it can travel in a regular
scanning pattern back and forth across the area of
interest, so that detected and amplified signals can be
plotted to give a picture or contour map of
radioactivity within the organ
509. • Usually, the detector-collimator assembly, the
photo-multiplier and the pre-amplifier are
housed in a single unit, which is attached to a
motor-driven device.
• This device defines the lateral and longitudinal limits
of the scan
510. • The scanning can be linear or one-dimensional. In the whole body
counting applications, the detector is moved continuously over the
body and the counts are integrated over the entire scan.
• The recording may be done either by a photographic recorder or
by dot recorders. In a photographic recorder, the light flashes
can be photographed on a film, from the face of a cathode ray tube.
511. • The dot recorder is most commonly used. It produces a map of the
distribution of activity within the area of interest by recording dots or slit-
like marks on paper.
• The dot recording mechanism consists of an electrically heated stylus to
burn a small spot on a sheet of electrically conducting paper, each time a
pulse passes through the stylus. The pulses to the stylus are delivered
from the pulse height analyzer after scaling down the counts by an
adjustable scaling factor from 1 to 256
512. • A scaling factor of 16, for example, would mean that for
every 16 counts arriving at the input of the scaling
circuit from the pulse height analyser, one dot appears
on the paper
• This reduction in counting rate is necessary, because
extremely high counting rates will drive the stylus wild.
A count-rate metre is also incorporated to display or
record the average count rate.
583. Patient safety and Electro
medical Equipment.
CHAPTER FIVE
Compiled by: Tsedale & Meka
584. The number of medical equipments in a modern
community hospital is increasing day by day. In
order to avoid electrical shock, excessive
radiation, toxic exposure fire, explosion and other
hazards, many of the devices should be desired
and handled with extreme care.
Electrical safety and patient shock hazards
associated with the use of biomedical electronic
equipment have become important problems for
biomedical engineers.
585. An electrical shock is an unwanted or unnecessary
physiological response to current. Electrical shock
may cause an unwanted cellular depolarization and
its associated muscular contraction, or it may cause
cell vaporization and tissue injury. The effect of
commercial frequency currents on the human body
should be considered. Most of the electrical
accidents involve a current pathway through the
victim from one upper limb to the feet or to the
opposite upper limb. At commercial frequencies,
the body acts as a volume conductor.
Electrical shock
586. Physiological effects due to 50Hz current passage:
The physiological effect of shock range from
discomfort to injury to death, if the heart or
respiratory system is affected
For commercial frequencies (50-60 Hz) specific
physiological effects due to passage of current
passing through the body are shown in the table
below
587. Type of current Current
Range(mA)
Physiological Effect
Threshold 1 – 5 Tingling Sensation
Pain 5 – 8 Intense of painful sensation
Let-go 8 – 20 Threshold of involuntary muscle
contraction
Paralysis >20 Respiratory Paralysis and pain
Fibrillation 80 – 1000 Ventricular and heart fibrillation
Defibrillation 1000 – 10,000 Sustained myocardial contraction,
temporary respiratory paralysis
and possible tissue burns.
588. Condition Skin resistance per square Centimeter of electrode
Dry Skin 93.0KΩ
Electrode gel on skin 10.8 KΩ
Penetrated Skin 200.0 Ω
One of the main hazards connected with the
use of medical equipment is electrical shock.
Shock is defined in terms of current because the
voltages that produce the current are highly
variable. The variance in voltage is caused by
wide variation in skin resistance among
individuals and among differing clinical
situations.
Table: Skin Resistance at 50 Hz
589. The let-go current is defined as the maximal current
at which the subject can withdraw voluntarily, and
the minimum current to produce muscular
contraction. Let-go current for men is about 16 mA
and for women is about 10.5 mA. Between 5 Hz to
200 Hz the value of let-go current is too low. Above
200 Hz, the let-go current is directly proportional to
the logarithm of frequency. Let-go current also
depends on weight and time of passage of current
through the body such that the magnitude of the let-
go current varies inversely with the weight and
square root of the current passage time in the case of
adults.
590. Macroshock:
A physiological response to a current applied to
the surface of the body that produces unwanted or
unnecessary simulation like muscle contractions or
tissue injury is called Macroshock.
All hospital patients and medical attendants are
exposed to macroshocks from defective electric
devices and biomedical equipment.
591. Microshock:
A physiological response to a current applied to
the surface of the heart that results in unwanted
simulation like muscle contractions or tissue injury
is called Microshock.
Microshock is most often caused when currents
in excess of 10µA flow through an insulated
catheter to the heart.
592. Shock Hazards:
Many devices have a metal chasis and cabinet that
can be touched by the medical attendants and
patients. If they are not grounded, then an insulation
failure or short circuit results and leads to
macroshock or microshock. If the patient is ill,
unconscious anaesthetized or strapped on the
rotating table, a tingling effect on the skin reveals
that the patient is receiving a shock. Such patents
must be isolated or insulated from the electrical
shock.
593. a. Leakage Currents:
Most of the accidents occur due to improper
grounding and leakage currents. The leakage
current is an extraneous current flowing along a
path other than those intended. It could be due to
resistive, inductive or capacitive couplings with
the mains or some electronic equipment.
A patient in an electrically operated bed which is
shown in fig 1 below has a pacemaker with bipolar
catheter going to the right ventricle of the heart via
the right juglar vein. The pacemaker’s case is
connected to the ground of the power cord.
594.
595. The leakage current flow is due to
•Ungrounded equipment
•Broken ground wire and
•Unequal ground potentials.
Broken ground connection on the electric bed allows a
voltage to exist on the bed frame due to capacitive
coupling between the bed frame and power line. The
pacemaker wire is going into the heart of the patient.
The heart activity is monitored by an ECG recorder.
Hence the leakage current flows from the motor of the
bed frame to the medical attendants hand to the patient’s
heart through the catheter or pacemaker wire and then to
the ground of the ECG unit as shown in fig
596.
597. b) Static Electricity
Static electricity may be dangerous to people and
sensitive equipment having integrated circuits.
Sparks from static electricity could ignite flammable
gasses, causing an explosion. It has been suggested
that shocks from static electricity could cause
cardiac arrest if applied to a pacing catheter. Floor
carpeting is very common source of static electricity
charge build up.
599. c. Interruption of power:
Interruption of electrical power to life support
equipment can also be hazardous. If a delay occurs
before emergency power is brought into operation,
the failure of a respirator monitor, defibrillator,
pacemaker or other life support equipment can be
fatal. The possibility of power failure must be
considered in the planning of a power distribution
system.
600. Macroshock Hazards:
Macroshock occurs more often with two wire
systems than three wires systems. With two wire
equipment it is always dangerous to get between the
phase (hot H) and the neutral N wires. If a patient
touches H and N wires simultaneously with two
limbs, then the currents are flowing directly through
vital organs of circulation and respiration. Because N
wires are internally grounded, touching H and G
wires can produce macroshock.
601. In (a), the H lead shorts to the patient lead P, thus a macroshock results if
the patient touches ground or the chassis. In fig (b), the hot wire H and
neutral N are reversed because the two wire plug has been reversed. A
grounded patient is therefore shocked upon touching the chassis.
602. In fig (c) the H wire shorted to the chassis, causing the shock
configuration shown as the patient touches either neutral or ground and
the chassis. In fig (d) the neutral wire accidently shorts to the
equipment case, leading to a shock situation of H to chassis or H to
ground. If the H line faults to N, no shock occurs unless the patient
touches H or N and ground.
603. Maintaining safe patient electrical Environment
1. Use only three wire power cable
2. Supply all electrical equipment within 5 meters of the
patient from a single bank of power points that have
grounded terminals tied together by 12 gauge or larger
wire.
3. Do not use any other electrical outlets in the vicinity of
the patient.
4. Supply the power points from a power line isolation
transformer with ground-fault monitors.
604. 5. Connect the conductive surfaces of all non-electrical
devices within 5 meters of the patient to a common
ground terminal with separate 12 gauge or larger, wire
for each device. Connect the common ground terminal
to the wall outlet ground.
6. Check the power cords for signs of damage and ground
continuity from the plug to the equipment case.
7. Use monitoring equipment with isolated inputs
8. With all the equipment turned on, measure the potential
between the common ground terminal and all
conductive surfaces within 5 meters of the patient. No
surface should be more than 5 mV from the ground.
9. There should be periodic inspection of all the equipment
and regular checks on ground continuity.
605. ELECTROSTATICALLY INDUCED CURRENTS
Utility Wiring Capacitance
Capacitive coupling between the mains voltage ( 220 V/115)
wiring and the subject constitutes an impedance which will
allow the current to flow through the subject.
607. Regulation of Medical Devices
The medical instrumentation industry in general
and hospitals in particular are required to be most
regulated industries. This is because when
measurements are made on human beings and by
the human beings, the equipment should not only
be safe to operate but must give intended
performance so that the patients could be properly
diagnosed and treated.
608. Regulations: A regulation is an organization’s way of
specifying that some particular standard must be adhered to.
These are the rules normally promulgated (Circulated) by
the government.
Standards: A standard is a multiparty agreement for
establishment of an arbitrary criterion for reference.
Alternatively, a standard is a prescribed set of rules,
conditions or requirements concerned with the definition of
terms, classification of components, delineation of
procedures, specifications of materials, performance, design
or operations, measurement of quality and quality in
describing of materials, products, systems, services or
practice.
609. Codes: A system of principles or regulations or a
systematized body of law or an accumulation of a system
of regulations and standards.
Specifications: Documents used to control the
procurement of equipment by laying down the
performance and other associated criteria. These
documents usually cover design criteria, system
performance, materials and technical data.
610. Types of Standards
There are in general three types of standards for medical
devices
Voluntary Standards: Developed through a consensus
process where manufactures, users, consumers and
government agencies participate. They carry no inherent
power of enforcement but provide a reference point of mutual
understanding.
Mandatory Standards: Required to be followed under law.
They are incumbent of those to whom the standard is
addressed and enforceable by the authority having jurisdiction.
Proprietary Standards: Developed either by the
manufacturer for its own internal use or by a trade association
for use by its members. They can be adopted as voluntary or
mandatory standards with the consensus/ approval of the
concerned agencies.
611. The rules and regulation resulted in medical devices
being classified into three categories. The device
class number is in ascending order of safety risk to
the patient in case of device failure.
Class-I device are subject to general controls, which
include labeling, registration, reporting, and
tracking, and adherence to general quality control
requirements. Example of these devices include
blades, bandages, medical tapes, tongue blades, and
gloves.
Regulatory Requirements
612. Class-II devices are subject to specific controls,
which include clinical trials and performance. A
thermometer is an example of a class-II device.
Class-III devices are subject to the aforementioned
general and specific controls, which require clinical
studies and show effectiveness and safety. The issue
of clinical studies and safety is part of premarket
approval controls(PMA). These include implantable
devices such as knee replacement and pacemakers.
