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Technology > Diathermy > Flashcards

Diathermy Flashcards

1
Q

diathermy current

A

hertz osscillations per second
400kHz-2.5mHz (10mHz)
standard current is 50-60Hz (hairdryer)
nerves stimulated 100Hz

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2
Q

plate vs electrode surface area

A

heat generated by high current density due to small surface area
treatment electrodevs patient electrode
high frequency current from generator

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3
Q

how does bipolar work

A

current down active electrode and back to generator rather than running through patient

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4
Q

cutting vs coag

A

coag 94% off 6% on
higher amplitude, low er voltage
non continuous
charring over large area

cutting 100% on
low voltage
intense rapid heat 1000C
vapourisation water in cells

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5
Q

where to apply pad

A

well vascularised muscle area with no hairs

70cm2 surface area

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6
Q

avoiding burns

A 
avoiding pooling alcohol prep
diathermy pad away from metal at least 15cm away
short term
use bipolar
patient no touching metal objects
burn = current x time / area
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7
Q

risks to implantable devices -2

A

phantom reprogramming - work in different mode
due to use of high frequency current stimulate the radiofrequency impulse by which pacemakers are reprogrammed

pacemaker inhibition, if dependent on beat may stop, if patient pacemaker depedent heart stops beating

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8
Q

what precautions to take for cardiac devices 4

A

all information on pacemakers
serial numbers, date implantation, hospital site, indication, result of last check, should have card with this information
cardiac clinic contacted for precise indication
try avoid diathermy

pacemaker check within 6 months
check post procedure
ICDs pre procedure to monitor only

plate elctrode not in path pacemaker
avoid inappropirate grounding ECG leads
diathermy machine well away from paceamker >1cm
heart monitored
defib available as well as ex pacemaker
short bursts
different types of ICD may not need turning off
follow hospital SOP for ICD
electrophysiology department
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9
Q

types of minimally invasive surgery burns

A

insulation failure
direct coupling - electrode and camera touching
capcitative coupling - charging of plastic port as an insulator which can discharge electricity to internal organs

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10
Q

how does harmonic work

A

coaptive coagulation
active blade vibraets 50kHz
compress vessel walls
controls bleeding at 100c lower temperatures
generates protein coagulum behind the point
up to 5mm

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11
Q

ligasure

A

bipolar diathermy and pressure combines metls collagen and elastin and reforms into seal
feedback loop stops energy once seal complete
up to 7mm
higher heat generation around ligasure

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12
Q

bipolar turp mechanism

A

size of bipolar loop

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13
Q

current

A

flow of electrons during a period of time measured in amperes

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14
Q

voltage

A

force pushing current through the resistance measured in volts

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15
Q

resitance

A

obstacle to the flow of current measured in ohms

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16
Q

what is electric current

A

electrons flow from one atom to the orbit of an adjacent atom.
voltage is the force or push that allows electrons to travel from atom to atom
if encounter resistance heat is produced

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17
Q

electrocautery vs electrosurgery

A

electrocautery only heated element in contact with patient body
direct current, flowing in one direction

in electrosurgery the patient is included in the circuit
uses alternating current

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18
Q

electrosurgery circuit

A

electrosurgical generator providing flow of electrons and voltage

active electrode

patient (tissue providing impedance)

patient return electrode

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19
Q

normal electrical current alternating frequency
why electrosurgery is higher
when does muscle and nerve stimulation cease
which frequencies safe

A

60 cycles per second 60Hz
would cause excessive NM stimulation
cease at 100,000 Hz or 100 KHz
so electrosurgery safe at 100Khz and above

the electrosurgical generator takes 60 cycle current and increases freq to 200KHz

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20
Q

bipolar

active and return electrode

A

both active and return electrode are at site of surgery
two tines of the forceps perform the active and return
only tissue grasped is included in electrical circuit
no patient return electrode needed

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20
Q

bipolar

active and return electrode

A

both active and return electrode are at site of surgery
two tines of the forceps perform the active and return
only tissue grasped is included in electrical circuit
no patient return electrode needed

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21
Q

monopolar electrosurgery

A

the active electrode is the surgical site
patient return electrode is somewhere else on body
current passes through patient and completes circuit

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22
Q

cut vs blend vs coag

A

produce a variety of electrical waveforms which produce different tissue effects
modification of the waveform so that the duty cycle or on time is reduced

high heat produced rapidly causes vaporisation

cut - vaporise or cut tissue
100% on
low voltage

coag 6% on, 94% off
produces less heat
coagulum produced
high voltage

blended - mixture of both from high to low duty cycle

23
Q

cutting

how it works

A

intense heat rapidly
using electrical sparks that focus intense heat at surgical site
by sparking to tissue produces maximum current concentration
to create spark hold slightly away from tissue

24
Q

variables influencing effect on tissue

A 
waveform
voltage
power setting
size electrode
time
manipulation electrode
type tissue
25
Q

what is current division

A

current split or divide and follow more than one path to ground
follows easiest most conductive path
any grounded object can complete circuit
resulting in ‘alternate site burns’

26
Q

what is isolated system

A

isolated generator technology
completed not by ground byt by the generator
even though grounded objects remain in op room
electrosurgical current from isolated generators will not recognise grounded objects as pathways to complete circuit
recognises patient electrode as preferred path back to generator

27
Q

what is isolated system

A

isolated generator technology
completed not by ground byt by the generator
even though grounded objects remain in op room
electrosurgical current from isolated generators will not recognise grounded objects as pathways to complete circuit
recognises patient electrode as preferred path back to generator

28
Q

return electrode burns

A

isolated circuits prevent alternate site burns but not return electode burns
return electrodes are not inactive nor passive
only differ from active electrode in their size and relative conductivity

29
Q

return electrode placement

A 
close to operative site
on conductive tissue
well vascularised muscle mass
avoid vascular insufficiency
irregular body contours
bony prominences
30
Q

return electrode monitoring

A

REM equipped generators must use a patient electrode that is compatible with split appearance
actively monitor the amount of impendance at patient return electroude at the patient/pad interface

31
Q

vessel sealing techology and enseal

A

uses biploar
feeback controlled
vessels up to 7mm
can withstand three times normal systolic BP
measures initial impedance of tissue and chooses appropirate settings
delivers pulsed energy with continuous feedback control
senses that tissue response is complete and stops the cycle

32
Q

safety considerations electrosurgery -3

A

direct coupling
insulation failure
capcitive coupling

33
Q

direct coupling

A

actives electrode whilst near another metal instrucment

second instrument become energised

34
Q

insultation failure

A

when using high voltage coag mode
high voltage can spark through compromised insulation or blow holes in weak insultation
breaks in insulation create an alternate route for current which if concentrated can cause injury

35
Q

capacitive coupling

A

inadvertant capicitator may be created by surgical instrument
capacitor creates an electrostatic field between the two conductors (condutive active electrode and condutive metal cannula)
as a result one conductor can through an electrostatic field induce a current in second conductor

36
Q

capacitive coupling

A

inadvertant capicitator may be created by surgical instrument
capacitor creates an electrostatic field between the two conductors (condutive active electrode and condutive metal cannula)
as a result one conductor can through an electrostatic field induce a current in second conductor

37
Q

avoiding electrosurgical complications in MIS 7

A 
inspect insulation
lower possible power
low voltage cut waveform
brief intermittent activation
not active near other instrument
bipolar
do not use hybrid cannula system
38
Q

safety precautions in theatre

A

not used near flammable alcohol agents
non condutive holster /quiver
cords not wrapped around metal instruments or bundled toegther in case of current leak

38
Q

safety precautions in theatre

A

not used near flammable alcohol agents
non condutive holster /quiver
cords not wrapped around metal instruments or bundled toegther in case of current leak

39
Q

duty cycle

A

the duty cycle (defi ned as the ratio of the “on” time to the period of a single
“on–off” cycle

40
Q

frequency bipolar diathermy

A

250KHz to 1Mhz

40
Q

frequency bipolar diathermy

A

250KHz to 1Mhz

41
Q

Gyrus vs TURIS system bipolar TURP

A

The Gyrus plasmaKinetic (PK) system™ is a bipolar coaxial system with the
active and return electrodes located in the same axis, separated by a ceramic insulator.
Such an intricate design has raised the cost of each resection loop. In the TURIS
system, (Olympus SurgMaster resectoscope™, with a 26F outer diameter), the
SurgMaster™ generates a high frequency current that passes through the active
electrode (resection loop) and returns via the return electrode (sheath of the resectoscope).
The generator is usually set for cutting, and coagulation at 180 and 100 W
respectively. This is a simpler and less costly bipolar design with potentially similar
clinical benefi ts.

42
Q

harmonic scalpel

A

simultaneously cuts and cauterises tissue
PE cyrstal in handpiece
active blader delivers US energy
high grade frictional foce and heat

ultrasonic energy mechanical in nature and works at much lower temperatures
controls bleeding by coaptive coagulation at lower temps
50 to 100C
coaption compression of vessel walls
followed by sealing with coagulation
intrsument blade vibrates at 55,500 Hz ie 55kHz
causes protein in the vessel wall to form a coagulum
but can result in heating of tip to 100C

43
Q

temperatures used in electorsurgery and lasers

A

Electrosurgery and lasers coagulate by burning at high temperatures
causing obliterative coagulation at between 150°C and 400°C

Blood and tissue are thereby desiccated and oxidised, forming a charred eschar that covers and
seals the bleeding area. Rebleeding can occur when the forceps used during electrosurgery
are removed, when they may stick to the cauterised tissue and disrupt the
eschar

44
Q

liagsure

A

electrothermal bipolar device
delivers bespoke temperature
to seal collagen and elastin

pressure and energy to create vessel fusion
radiofrequency energy to melt the collagen and elastin in vessel walls and reforms it into a permanent plastic like seal
does not rely on proximal thrombus
feedback controlled response system stops energy delivery
mimises thermal spread 2mm
free of sticking or charring
can wtihstand 3 x normal BP
vessels up to 7mm

44
Q

liagsure

A

pressure and energy to create vessel fusion
radiofrequency energy to melt the collagen and elastin in vessel walls and reforms it into a permanent plastic like seal
does not rely on proximal thrombus
feedback controlled response system stops energy delivery
mimises thermal spread 2mm
free of sticking or charring
can wtihstand 3 x normal BP
vessels up to 7mm

45
Q

what frequency of current increases risk current leakage to tissues

A

> 3MHz

46
Q

what temp does vapourisation occur

A

ie. cut is over 200c

coagulation is over 45 degrees

47
Q

bipolar and creation of plasma

A

plasma is one of the four fundamental states of matter
created by applying energy to a gas
molecules then ionised turning gas into plasma
plasma is conductive, allows energy to cross at lower energy levels
leads to lower operating temperatures and less thermal spread
tissue vapourised by locally confied denaturation proces
while surrounding tissue effects minor
TURIS system

48
Q

what is diathermy

A

passage of high frequency alternating current in the range 400khz to 10 Mhz through body tissue
where the current is concetrated heat up to 1000C is produced to allow cutting or coagulation

49
Q

why nerves and muscles not stimulated

A

stimulated at 100khz or below

with such high frequency no time for cell membranes to become depolarised

50
Q

surface area of diathermy plate

A

70 to 150 cm squared

51
Q

power of cutting vs coag

A

125-250W

coag is 10-75W

52
Q

how does blend work

A

only in cutting mode

50% duty cycle on/off

53
Q

main complications diathermy

A 
flammable
explosion
patient plate site
obsturator kick
end artery necrosis
pacemakers

Technology (24 decks)

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