Radiology & MRI
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Transcript Radiology & MRI
الکتروفیزیولوژی قلب
رضا ارجمند
زمستان 84
رئوس مطالب
ساختار قلب
ساختار الکتریکی قلب
بردار قلبی
لیدهای ECG
مسایل مطرح در ECG
سلولهای قلبی
Working muscle cells
Specialized condition cells
Pacemaker cells
SA
node
قلب
Transmembrane Potential
طبیعت الکتریکی ارتباط بین سلولی
ساختار Gap Junction
دلیل تجربی برای عملکرد مداوم در عضله قلبی
اطالعات جدید در مورد مقاومت Gap junc.
شمایی از قرارگیری سلولها
دلیل تجربی برای عملکرد مداوم در عضله قلبی
ثابت زمانی 18 msو ثابت مکانی 1mm
نتایج نشان مد دهند که فضای میان سلولی از نظر
الکتریکی به هم متصلند.
تقسیم بندی زمانی انتشار
اطالعات جدید در مورد مقاومت Gap junc.
اطالعات جدید در مورد مقاومت Gap junc.
(ادامه)
با قراردادن V2=0داریم:
اطالعات جدید در مورد مقاومت Gap junc.
(ادامه)
نتایج:
با قراردادن V1در -42 mVجریان رو به داخل سدیم متوقف
و جریان رو به داخل کلسیم و رو به بیرون پتاسیم آغاز می
گردد.
مقدار rnمستقل از V1بوده و برابر M1.7می باشد.
این عدد با جابخایی سلول ها هم ثابت باقی می ماند.
عملکرد دیوار آزاد قلب
انتشار در هر جهت امکان دارد که انجام پذیرد.
در راستای سلول دارای بیشترین سرعت و هدایت می باشد
عملکرد دیوار آزاد قلب (ادامه)
خواهیم داشت:
)Heart Vector (Dipole
انتگرال کل دو قطبی ها منجر به دو قطبی واحد قلب می
گردد که بردار قلبی نیز نامیده می شود.
قلب از جهت الکتریکی به عنوان ژنراتور دو قطبی
H تابعی از زمان ولی Jتابعی از زمان و مکان می باشد.
Frontal Plane Leads:
Standard (bipolar) Leads:
I: RA- to LA+
II: RA- to LL+
III: LA- to LL+
Augmented Vector (Unipolar) Leads
aVR: to RA+
aVL: to LA+
aVF: to LL+
لیدهای استاندارد (ادامه)
مثلث ایندهوون
لیدهای تقویت شده
Precordial Leads
Wilson central terminal
Precordial Leads= V1-V6
Place Electrodes
مسایل موجود در ECG
اعوجاج فرکانسی
حلقه های زمین
آرتیفکتهای گذرا
تداخل ها
ونتیالتور
Reza Arjmand
Winter 84
رئوس مطالب
مکانیزم تنفس طبیعي
انواع وسایل کمک تنفسي
مکانیسم تنفس طبیعي
دو روش عمده براي حرکي باال پایین سینه
حرکت دیافراگم (شکل )C-1
حرکت باال و پایین دنده ها براي زیاد و کم کردن قطر
قدامي
انواع وسایل کمک تنفسي
وسایلي که هنگام مشکل تنفسي بکار مي برند:
کنترل کننده ها
کمک کننده ها
انواع روشهاي مکانیکي ونتیالسیون
ونتیالسیون با فشار منفي
ونتیالسیون با فشار مثبت
مدار الکتریکي و مکانیکي تنفس
مقاومت مسیر R
معادل Cتنفس و
ظرفیت خازني
است و ونتیالتور
برابر منبع ثابت
جریان و پتانسیل
مدل
مي گردد.
کمیت هاي مورد نظر در هر ونتیالتور
حجم دمي
حجم جاري
نسبت تنفس
فشار پر شدن ریه
ظرفیت هوایي مسیر هوایي
مقاومت مسیر هوایي
انواع مدهاي عملیاتي ونتیالتور ها
سیکل فشار PCV
سیکل حجمي VCV
سیکل زماني TCV
سیکل فلو FCV
کنترل کننده تنفس
MRI رادیولوژی و
Arjmand Reza
Azar Ayaz Co.
[email protected]
Radiology
خاصیت یونیزه كنندگي
اشعه عبوري
در اثر بر خورد الكترونهاي پر شتاب و تغییرات انرژي
آنها
مشخصات اشعه X
سختي اشعه (قابلیت نفوذ متناسب با )Kv
چگالي تابش (متناسب با )Ma
)Io=Ii exp(-ux
بستگي به پراكندگي و جذب دارد U:
ضخامت x:
:Spet size قطر قسمت خروجي اشعه
عمده صدمات تیوب
صدمات آند( :گرماو حرارت)
* ذوب شدن سطح آند
* ترك خوردن سطح آند
* exposeهاي متوالي با فاصله كم
صدمه به یاتاقان
صدمه به شیشه
مراحل آماده سازي متعارف
.1كلید On
Preheating .2كاتد
Ready .3گرفتن
.1-3افزایش جریان
.2-3شروع چرخش اند تا سرعت نامي
Expose .4
MRI
از طریق قرار دادن بدن در میدان مغناطیسي
در بدن دو قطبي هاي نامنظم وجود دارند.
MRI
سرعت و جهت دوران این دو قطبي ها تصادفي است.
اعمال یك میدان بسیار قوي در راستاي همسو سازي
اعمال میدان دوم (با زاویه مناسب)
قطع میدان
و لستفاده از پالس هاي تولیدي
اشكاالت MRI
زمان بسیار زیاد
عدم استفاده براي كسانیكه فلز در بدن دارند.
میدان مغناطیسي باال
با تشکر
Monitoring Pulse Oximetry
By Arjmand Reza
Azar Ayaz Co.
Respiratory Compromise
Signs and Symptoms
Dyspnea
Accessory
muscle use
Inability to speak in full sentences
Adventitious breath sounds
Increased or decreased breathing rates
Shallow breathing
Flared nostrils or pursed lips
continued
Retractions
Upright or tripod position
Unusual anatomy changes
Hypoxemia
Decreased oxygen in arterial blood
Results
in decreased cellular oxygenation
Anaerobic metabolism
Loss of cellular energy production
Hypoxemia Etiology
Inadequate External Respiration
Decreased
capillaries
Inadequate Oxygen Transport
Decreased
on-loading of oxygen at pulmonary
oxygen carrying capacity
Inadequate Internal Respiration
Decreased
capillaries
off-loading of oxygen at cellular
External Respiration
Exchange of gases between the alveoli
and pulmonary capillaries
Oxygen diffuses from an area of higher
concentration to an area of lower oxygen
concentration
Oxygen must be available and must be
able to diffuse across alveolar and
capillary membranes
Oxygen must be able to saturate the
hemoglobin
Inadequate External Respiration
Decreased oxygen available in the
environment
Smoke
inhalation
Toxic gas inhalation
High altitudes
Enclosures without outside ventilation
Inadequate mechanical ventilation
Pain
Rib
fractures
Pleurisy
continued
Traumatic
injuries
Open pneumothorax
Loss of ability to change intrathoracic pressures
Crushing injuries of the
Traumatic asphyxia
Crushing neck injuries
neck and chest
Tension pneumothorax
Increased intrathoracic pressures reducing ventilation
Hemothorax
Blood in thoracic cavity reducing lung expansion
Flail Chest
Loss of ability to change intrathoracic pressures
continued
Other
conditions
Upper
Epiglottitis
Croup
Airway Edema-anaphylaxis
Lower
Airway Obstruction
Airway Obstructions
Asthma
Airway Edema from inhalation of toxic substances
continued
Hypoventilation
Muscle
Spinal injuries
Paralytic drug for intubation
Drug
Overdose
Respiratory depressants
Brain
Paralysis
Stem Injuries
Damage to the respiratory center
continued
Inadequate oxygen diffusion
Pulmonary
edema
Fluid
between alveoli and capillaries inhibit
diffusion
Pneumonia
Consolidation
reduces surface area of respiratory
membranes
Reduces the ventilation-perfusion ratio
COPD
Air
trapping in alveoli
Loss of surface area of respiratory membranes
continued
Pulmonary
Area
emboli
of the lung is ventilated but hypoperfused
Loss of functional respiration membranes
Oxygen Transport
Most of the oxygen in arterial blood is
saturated on hemoglobin
Red blood cells must be adequate in
number and have adequate hemoglobin
Sufficient circulation is necessary to
transport oxygen to the cellular level
Inadequate Oxygen Transport
Anemia
Poisoning
Reduces red blood cells reduce oxygen carrying
capacity
Inadequate hemoglobin results in the loss of oxygen
saturation
Carbon monoxide on-loads on the hemoglobin more
readily preventing oxygen saturation and oxygen
carrying capacity
Shock
Low blood pressures result in inadequate oxygen
carrying capacity
Internal Respiration
Exchange of gases from the systemic
capillaries to the tissue cells
Oxygen must be able to off-load the
hemoglobin
Oxygen moves from a area of higher
concentration to an area of lower
concentration of oxygen
Inadequate Internal Respiration
Shock
Cellular environment is not conducive to offloading oxygen
Oxygen is not available due to massive peripheral
vasoconstriction or micro-emboli
Acid Base Imbalance
Lower than normal temperature
Poisoning
CO will reduce the oxygen available at the cellular
level
Signs and Symptoms of Hypoxemia
Restlessness
Altered or deteriorating mental status
Increased or decreased pulse rates
Increased or decrease respiratory rates
Decreased oxygen oximetry readings
Cyanosis (late sign)
Pathophysiology
Oxygen is exchanged by diffusion from
higher concentrations to lower
concentrations
Most of the oxygen in the arterial blood is
carried bound to hemoglobin
97%
of total oxygen is normally bound to
hemoglobin
3% of total oxygen is dissolved in the plasma
Oxygen Saturation
Percentage of hemoglobin saturated with
oxygen
Normal SpO2 is 95-98%
Suspect cellular perfusion compromise if
less than 95% SpO2
Insure
adequate airway
Provide supplemental oxygen
Monitor carefully for further changes and
intervene appropriately
continued
Suspect severe cellular perfusion
compromise when SpO2 is less than 90%
Insure
airway and provide positive ventilations
if necessary
Administer high flow oxygen
Head injured patients should never drop
below 90% SpO2
SpO2 and PaO2
SpO2 indicates the oxygen bound to
hemoglobin
Closely
corresponds to SaO2 measured in
laboratory tests
SpO2 indicates the saturation was obtained
with non-invasive oximetry
PaO2 indicates the oxygen dissolved in the
plasma
Measured
in ABGs
continued
Normal PaO2 is 80-100 mmHg
Normally
80-100
mm Hg corresponds to 95-100% SpO2
60 mm Hg corresponds to 90% SpO2
40 mm Hg corresponds to 75% SpO2
Technology
The pulse oximeter has Light-emitting
diodes (LEDs) that produce red and
infrared light
LEDs and the detector are on opposite
sides of the sensor
Sensor must be place so light passes
through a capillary bed
Requires
physiological pulsatile waves to
measure saturation
Requires a pulse or a pulse wave (Adequate
CPR)
continued
Oxygenated blood and deoxygenated
blood absorb different light sources
Oxyhemoglobin
absorbs more infrared light
Reduced hemoglobin absorbs more red light
Pulse oximetry reveals arterial saturation my
measuring the difference.
Patient Assessment
Patient assessment should include all
components
Scene
Size-up
Initial Assessment
Rapid Trauma Assessment or Focused Physical
Exam
Focused History
Vital Signs
Detailed Assessment
Ongoing Assessment
Pulse Oximetry Monitoring
Pulse oximetry monitoring is NOT
intended to replace any part of the patient
assessment
Pulse
oximetry is a useful adjunct in assessing
the patient’s oxygenation and monitoring
treatment interventions
Initiate pulse oximetry immediately prior
to or concurrently with oxygen
administration
Continuous Monitoring
Monitor current oxygenation status and
response to oxygen therapy
Monitor response to nebulized treatments
Monitor patient following intubation
Monitor patient following positioning
patients for stabilization and transport
Decreased circulating oxygen in the
blood may occur rapidly without
immediate clinical signs and
symptoms
Pediatrics
Use appropriate sized sensors
Adult
sensors may be used on arms or feet
Active movement may cause erroneous
readings
Pulse
rate on the oximeter must coincide with
palpated pulse
Poor perfusion will cause erroneous
readings
Treat
patient according to clinical status when
in doubt
Pulse oximetry is useless in pediatric cardiac
Conditions Affecting Accuracy
Patient conditions
Carboxyhemoglobin
Anemia
Hypovolemia/Hypotension
Hypothermia
Patient Environments
Ambient Light
Excessive Motion
Ambient Lighting
Any external light exposure to capillary
bed where sampling is occurring may
result in an erroneous reading
Most sensors are designed to prevent light
from passing through the shell
Shielding
the sensor by covering the extremity
is acceptable
Excessive Motion
New technology filters out most motion
artifact
Always compare the palpable pulse rate
with the pulse rate indicated on the pulse
oximetry
If
they do not coincide, reading must be
considered inaccurate
Other Concerns
Fingernail polish and pressed on nails
Most
commonly use nails and fingernail polish
will not affect pulse oximetry accuracy
Some shades of blue, black and green may
affect accuracy (remove with acetone pad)
Metallic flaked polish should be removed with
acetone pad
The sensor may be placed on the ear if
reading is affected
continued
Skin pigmentation
Apply
sensor to the fingertips of darkly
pigmented patients.
Interpreting Pulse Oximetry
Assess
and treat the PATIENT
not the oximeter!
Use
oximetry as an adjunct to patient
assessment and treatment evaluation
NEVER withhold oxygen if the
patient ahs signs or symptoms
of hypoxia or hypoxemia
irregardless of oximetry
readings!
continued
Pulse oximetry measures oxygenation not
ventilation
Pulse
oximetry does NOT indicate the removal
of carbon dioxide from the blood!
Documentation
Pulse oximetry is usually documented as
SpO2
Distinguishes
non-invasive pulse oximetry
from SaO2 determined by laboratory testing
Document oximetry readings as frequently
as other vital signs
When oximetry reading is obtained before
oxygen administration, designate the
reading as “room air”
continued
When oxygen administration is changed,
document the evaluation of pulse oximetry
When treatments provided could
potentially affect respiration or ventilation,
document pulse oximetry
Spinal
immobilization
Shock position
Fluid administration
pCO2 Electrode
The measurement of pCO2 is based on its linear relationship
with pH over the range of 10 to 90 mm Hg.
H2 O CO2 H2 CO3 H HCO3
The dissociation constant is given by
H HCO
k
3
a pCO2
Taking logarithms
pH = log[HCO3-] – log k – log a – log pCO2
pO2 electrode
The pO2 electrode consists of a platinum cathode and a
Ag/AgCl reference electrode.
Absorption
oxyhemoglobin
Optical Biosensors
deoxyhemoglobin
Sensing Principle
Wavelength
600 – 900 nm
They link changes in light intensity to changes in mass
or concentration, hence, fluorescent or colorimetric
molecules must be present.
Infrared
LED Spectroscopy
Various principles
and methods are
IR
used :
light
Finger
Optical fibres,
surface plasmon
resonance,Absorb
ance,
Luminescence
Photodetector
Fiber Optic Biosensor
Light
transmitter
Balloon
Thermistor
Intraventricular
Fiber optic catheter
Receiver/
reflected
light
Absorption/Fluorescence
Different dyes show peaks of different values at different
concentrations when the absorbance or excitation is plotted
against wavelength.
Phenol Red is a pH sensitive reversible dye whose relative
absorbance (indicated by ratio of green and red light
transmitted) is used to measure pH.
HPTS is an irreversible fluorescent dye used to measure pH.
Similarly, there are fluorescent dyes which can be used to
measure O2 and CO2 levels.
Pulse Oximetry
The pulse oximeter is a
spectrophotometric device
that detects and calculates
the differential absorption
of light by oxygenated and
reduced hemoglobin to get
sO2. A light source and a
photodetector are
contained within an ear or
finger probe for easy
application.
Two wavelengths of monochromatic light -- red (660 nm) and infrared
(940 nm) -- are used to gauge the presence of oxygenated and reduced
hemoglobin in blood. With each pulse beat the device interprets the
ratio of the pulse-added red absorbance to the pulse-added infrared
absorbance. The calculation requires previously determined calibration
curves that relate transcutaneous light absorption to sO2.
Summary
As with all monitoring devices, the
interpretation of information and
response to that interpretation is
the responsibility of a properly
trained technician!
References
Bledsoe, B. et al. (2003). Essentials of paramedic care. Upper Saddle River,
New Jersey: Prentice Hall.
Halstead, D., Progress in pulse oximetry—a powerful tool for EMS providers.
JEMS, 2001: 55-66.
Henry, M., Stapleton, E. (1997). EMT prehospital care (2nd ed.). Philadelphia:
W.B. Saunders.
Limmer, D., et al. (2001) Emergency Care (9th ed.). Upper Saddle River, New
Jersey: Prentice Hall.
Porter, R., et al: The fifth vital sign. Emergency, 1991 22(3): 127-130.
Sanders, M., (2001). Paramedic textbook (rev. 2nd ed.). St. Louis: Mosby.
Shade, B., et al. (2002). EMT intermediate textbook (2nd ed.). St. Louis:
Mosby.
Endoscopy
Arjmand Reza
Biomedical Engineering
Azar ayaz Co. (Ltd)
Principle of Endoscope: TIR
Case A
Case B
Case C
90o
θc
Figure 5.41 Total Internal Reflection (TIR).
Case D
Higher n
Lower n
Lower
n n
Higher
θ> θc (Condition of TIR)
Light Propagation in the Fiber Core
cladding
core
Figure 6.3 Illustration of total internal reflection in a fiber optic cable.
Brief History of Fiber Optics
Lanterns for communications (Paul Revere)
Lamps used by Navy personnel to communicate from
ship to ship or shore using Morse code.
First optical telegraph (late part of the 18th century, the
French). Towers stretching 230 km relayed signals from
one to the next using movable signal arms, enabling
message transmission in 15 minutes. A similar system
was operational between Boston and Martha’s Vineyards.
(Optical telegraph replaced by electrical telegraphs
later).
Brief History of Fiber Optics
(continued)
Spout
Light
Source
Light confined inside the
“water fiber”
Figure 6.1 Illustration of John Tyndall’s experiment with a “water” fiber.
Brief History of Fiber Optics
(continued)
Alexander Graham Bell invented the photo phone in the later part of the
19th century.
Use of fibers to look inside a human body started over fifty years ago.
The term “fiber optic” coined by Narinder Kapany in 1956. Glass rod with a
glass coating was invented and it became the first optical fiber.
The invention of laser in the 1960s evoked further interest in the field of
communications. Over the next few decades, losses in fiber optic cables
were reduced from ca. 20 dB/km in 1966, to ca. 0.2 dB/km or less these
days.
In the 1970’s, the military replaced conventional communication methods
with fiber optics due to the light weight offered by fiber cables.
Communication companies started replacing existing cabling with fiber optic
systems in the 1970s and 1980s.
In the 1990s computer manufacturing companies started using fiber optic
systems for rapid communications transfer with rates of up to 40 billion
bytes per second by the late 1990s.
Elements of a Fiber Optics Cable
for Communications
Outer Jacket
Kevlar®
Jacket
Buffer coat
Cladding
Core
Figure 6.2 Illustration of the elements of a fiber optic cable.
Introduction to Endoscopy
It is a minimally invasive diagnostic medical procedure
used to evaluate the interior surfaces of an organ by
inserting a small scope in the body, often but not
necessarily through a natural body opening. Through the
scope, one is able to see lesions.
An instrument may not only provide an image but also
enable taking small biopsies and retrieve foreign objects.
Endoscopy is the vehicle for minimally invasive surgery.
Many endoscopic procedures are relatively painless and
only associated with mild discomfort, though patients are
sedated for most procedures. Complications are rare but
may include perforation of the organ under inspection
with the endoscope or biopsy instrument. If this occurs,
surgery may be required to repair the injury.
Components
Uses a light delivery system to illuminate the organ
under inspection. Nowadays the light source is outside
the body and the light is typically directed via an optical
fiber system.
Transmits the image through a lens system, and in
flexible systems a fiberscope to the viewer.
In recent years has a camera, called a capsule camera or
video pill at the distal end of the optical system to
project findings on a video system.
Operative endoscopes have an additional channel to
allow entry of instruments to biopsy or operate.
Applications
The gastrointestinal tract:
esophagus, stomach and duodenum
(esophagogastroduodenoscopy)
colon (colonoscopy), the endoscope is used to examine the
colon.
sigmoid colon: (proctosigmoidoscopy)
in an endoscopic retrograde cholangiopancreatography
(ERCP), an endoscope is used to introduce radiographic
contrast medium into the bile ducts so they can be visualized
on x-ray.
The respiratory tract
The nose (rhinoscopy)
The lower respiratory tract (bronchoscopy)
The urinary tract (cystoscopy)
Applications
The female reproductive system
Normally closed body cavities (through a small
incision):
The uterus (hysteroscopy)
The Fallopian tubes (Falloscopy)
The abdominal or pelvic cavity (laparoscopy)
The interior of a joint (arthroscopy)
Organs of the chest (thoracoscopy and mediastinoscopy)
During pregnancy
The amnion (amnioscopy)
The fetus (fetoscopy)
History of the Endoscope
The first endoscope developed in 1806 by Philip Bozzini with his
introduction of a "Lichtleiter" (light conductor) "for the
examinations of the canals and cavities of the human body".
However, the Vienna Medical Society disapproved such curiosity.
Endoscope was first introduced into a human in 1853. The use of
electric light was a major step to improve endoscopy, first such
light was external, then smaller bulbs became available, making
internal light possible, for instance in a hysteroscope by David in
1908.
Jacobeus has been given credit for early endoscopic explorations
of the abdomen and the thorax with "laparoscopy" (1912) and
"thoracoscopy" (1910).
Laparoscopy was used in the diagnosis of liver and gallbladder
disease was by the German Heinz Kalk in the 1930s. Hope
reported in 1937 on the use of laparoscopy to diagnose ectopic
pregnancy.
In 1944 Raoul Palmer placed his patients in the Trendelenburg
position after gaseous distention of the abdomen and thus was
able to reliably perform gynecologic laparoscopy.
For diagnostic endoscopy Basil Hirschowitz invented a
superior glass fiber for flexible endoscopes. The
technology resulted in not only the first useful medical
endoscope, but the invention revolutionized other
endoscopic uses and led to practical fiber optics.
Surgery and examination began in the late 1970s and
then only with young and 'healthy' patients.
By 1980 laparoscopy training was required by
gynecologists to perform tubal ligation procedures and
diagnostic evaluations of the pelvis.
The first laparoscopic cholecystectomy was performed in
1984 and the first video-laparoscopic cholecystectomy in
1987.
During the 1990s laparoscopic surgery was extended to
the appendix, spleen, colon, stomach, kidney, and liver.
Recent developments
With the application of robotic systems, telesurgery was
introduced as the surgeon could operate from a site
physically removed from the patient. The first
transatlantic surgery has been called the Lindbergh
Operation.
In 2001 Given Imaging introduced the first pill-sized
endoscopic capsule with a camera. Over the following
years other manufacturers introduced new models with
additional improvements.
As of 2004, 1 cm x 2 cm endoscopic capsules can
capture 0.4 megapixel video at up to 30 frames/ second.
They give doctors rotational control over the capsule to
adjust the camera direction, can take tissue samples and
can deliver medications to patient's body. The capsules
cost upwards from $120 and can be powered by battery
or wireless transmission.
References
S. Vasan, Basics of Photonics and Optics,
Trafford Publishing, 2004
Wikipedia.org website
Olympus website.