Download Lecture 7 Chapter 13:Therapeutic/Prosthetic

Defibrillators
WHO. “Defibrillator, External, Automated; Semiautomated.” From the
publication: Core Medical Equipment. Geneva, Switzerland, 2011.
Summary
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Quiz
Clinical Use
History
Specifications
Principles of Operation
Block Diagram
• Commercial Examples
• Preventive
Maintenance
• Common Problems
• Test Procedures
Quiz
1. What is the 2 main clinical cases that require
the use of defibrillator?
2. What are the different types of defibrillator?
3. What is the defibrillator waveform polarity?
4. Does one need to use gel? Why?
Quiz
5. What kind of paddles can be used?
6. Draw the 2 possible of paddles placement in the case
of external electrodes.
7. Can one use a defibrillator with a patient on a OR
table? Why?
8. What are 2 ways to test a defibrillator
9. What is the most common problem in defibrillators from
the developing world?
Fibrillation
• Cardiac arrest occurs in more than 500,000
people annually in the United States
• Atrial fibrillation (AF) is relatively common
and can be well tolerated by the patient
Fibrillation
Jer5150 (2012) Fibrillation [Image], retrieved from https://commons.wikimedia.org/wiki/File:Ventricular_fibrillation.png
Ventricular Fibrillation
• Ventricular fibrillation (VF) causes the
heart to stop pumping blood immediately
• Irreversible brain damage or death after 5
minutes
• Most common cause of death
Clinical Use
• Reverse fibrillation of the heart (300 J to 360 J)
[Drawing of defibrillator pads placement] retrieved from www.wikipedia.com
• Restoring the heart’s normally coordinated
contractions (below 200 J) – Requires ECG
History
• 1899
– Physiologists Prevost and Batelli
from University of Geneva used
small electric shocks to induce
ventricular fibrillation in dogs, and
larger charges to reverse the
condition
History
• 1947
–First use on a human by
Claude Beck, professor of
surgery at Case Western
Reserve University
Specifications
• Input
– Electrical: ECG
signal
• Output
– Electrical: 3000 V
pulse during 10 ms
– Electronically
(display)
PhilippN, (November 2007), Position of
Electrodes during Defibrillation, retrieved
from
https://commons.wikimedia.org/wiki/File:De
fibrillation_Electrode_Position.jpg
Principles of Operation
• Electric current is
placed through
electrodes:
– Directly on the heart low current – 300 V
AC.
– Transthoracically –
large area electrodes,
higher current – 1000
V AC
[Photograph of defribrilator] retrieved from www.wikipedia.com
Types of Defibrillators
• Manual defibrillator (most
common in developing world)
• Automated external
defibrillators
AED (Home defibrillator)
WHO. “Defibrillator, External,
Automated; Semiautomated.” From the
publication: Core Medical Equipment.
Geneva, Switzerland, 2011.
• Implantable defibrillator
Steven Rodriquez (2007), Defibrillator [photograph], retrieved from
https://www.flickr.com/photos/n28ive1/431939091
Output Pulses
• Edmark Waveform
– Maximum Pulse 7,500 V
– Common in the poor world
– Severe damage (death)
– Be clear of the patient during the discharge
vp
2kv
~10 ms
Virginia Reid (2015), Waveform [drawing]
Output Pulses
Virginia Reid (2015), Output Pulses, [drawing]
Monophasic truncated
exponential
Biphasic truncated
exponential
Safest Waveform
Manual Defibrillators
ECG
• ECG leads can also
be connected from the
device to the patient
• However, most can
monitor the ECG
through the
defibrillation paddles
as well.
Aededitor (2011), Semi-automated external monitor defibrillator [photograph],
retrieved from https://commons.wikimedia.org/wiki/File:Semi-automated-externalmonitor-defibrillator.jpg
Synchronization
Shock point
Husche (2015), ECG Figure EN [diagram]. Adapted from https://commons.wikimedia.org/wiki/File:CCM_ECG_Figure_EN.png
ECG Synchronization
Anthony Atkielski (2012), Sinus Rhythm Labels [diagram]. Retrieved from https://commons.wikimedia.org/wiki/File:SinusRhythmLabels_fi.svg
Paddles
• Excellent contact with the body is essential
– Gel required
– Serious burns can occur if proper contact is
not maintained during discharge
• Sufficient insulation is required
– Prevents discharge into the physician
Paddles Types
• Internal: direct cardiac stimulation
• External: transthoracic stimulation
– Adult
– Pediatric
• Disposable: used externally
Paddles Types
• Disposable
• Internal
• External
Yury Masloboev (2007), Defibrillator, [photograph]. Retrieved from https://commons.wikimedia.org/wiki/File:Defibrillator_(UOMZ).jpg
Paddles Position
DHTLab (2015), Defibrilator Packet, retrieved from BMET Library
Paddles Position
Owain Davies (2012), Defib electrode placement, retrieved from https://commons.wikimedia.org/wiki/File:Defib_electrode_placement.png
Schematics
Openstax College. “Cardiac Muscle and Electrical Activity.” From the publication: Biology. Rice University: 2013.
Internal (Implantable) Defibrillator
BruceBlaus (2013), Implantable Cardioverter Defibrilator [diagram]. Retrieved from
https://commons.wikimedia.org/wiki/File:Blausen_0543_ImplantableCardioverterDefibrillator_InsideLeads.png
Commercial Examples
External Defibrillator
Openstax College. “Cardiac Muscle and Electrical Activity.” From the publication:
Biology. Rice University: 2013.
Commercial Examples
Internal Defibrillator
Steven Rodriquez (2007), Defibrillator [photograph], retrieved from
https://www.flickr.com/photos/n28ive1/431939091
Gregory Marcus (2008) Implantable cardioverter defibrillator chest X-ray
[photograph] retrieved from
https://commons.wikimedia.org/wiki/File:Implantable_cardioverter_defibrill
ator_chest_X-ray.jpg
Commercial Examples
AED
Wikipedia. “Automated External Defibrillator.”
Wikipedia, p. 1-5. Retrieved from:
https://en.wikipedia.org/wiki/Automated_external_def
ibrillator
Safety
• Avoid conducting mattress (spring),
bedstead or metal table
• Wear surgeon’s rubber gloves with highvoltage insulation
• CAUTION: high current and voltage
associated with the circuitry.
• Use GEL
Werneuchen (2008) Surgical Gloves [photograph].
Retrieved from
https://commons.wikimedia.org/wiki/File:Surgical_glov
es_26.JPG
Preventive Maintenance
• Replaced battery every 24 months
• Defibrillators offer a selftest option which
should be done at least once a month
Common Problems
• Old Batteries
• Paddles and cables contact
• The gel build up on the paddles and have to be
cleaned with alcohol
Test Procedures
• Paddles should be inspected for pit marks
• They could leave burns on the chest
Test Procedures
• Defribillator Selftest
• Use a fresh meat (normally pig)
NEVER TEST THE PADDLES
AGAINST EACH OTHER!
Questions
?
Troubleshooting