Diathermy

Question 1

diathermy current

Answer 1

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

Question 2

plate vs electrode surface area

Answer 2

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

Question 3

how does bipolar work

Answer 3

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

Question 4

cutting vs coag

Answer 4

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

Question 5

where to apply pad

Answer 5

well vascularised muscle area with no hairs

70cm2 surface area

Question 6

avoiding burns

Answer 6

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

Question 7

risks to implantable devices -2

Answer 7

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

Question 8

what precautions to take for cardiac devices 4

Answer 8

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

Question 9

types of minimally invasive surgery burns

Answer 9

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

Question 10

how does harmonic work

Answer 10

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

Question 11

ligasure

Answer 11

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

Question 12

bipolar turp mechanism

Answer 12

size of bipolar loop

Question 13

current

Answer 13

flow of electrons during a period of time measured in amperes

Question 14

voltage

Answer 14

force pushing current through the resistance measured in volts

Question 15

resitance

Answer 15

obstacle to the flow of current measured in ohms

Question 16

what is electric current

Answer 16

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

Question 17

electrocautery vs electrosurgery

Answer 17

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

Question 18

electrosurgery circuit

Answer 18

electrosurgical generator providing flow of electrons and voltage

active electrode

patient (tissue providing impedance)

patient return electrode

Question 19

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

Answer 19

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

Question 20

bipolar

active and return electrode

Answer 20

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

Question 20

bipolar

active and return electrode

Answer 20

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

Question 21

monopolar electrosurgery

Answer 21

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

Question 22

cut vs blend vs coag

Answer 22

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

Question 23

cutting

how it works

Answer 23

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

Question 24

variables influencing effect on tissue

Answer 24

``` waveform voltage power setting size electrode time manipulation electrode type tissue ```

Question 25

what is current division

Answer 25

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'

Question 26

what is isolated system

Answer 26

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

Question 27

what is isolated system

Answer 27

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

Question 28

return electrode burns

Answer 28

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

Question 29

return electrode placement

Answer 29

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

Question 30

return electrode monitoring

Answer 30

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

Question 31

vessel sealing techology and enseal

Answer 31

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

Question 32

safety considerations electrosurgery -3

Answer 32

direct coupling insulation failure capcitive coupling

Question 33

direct coupling

Answer 33

actives electrode whilst near another metal instrucment | second instrument become energised

Question 34

insultation failure

Answer 34

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

Question 35

capacitive coupling

Answer 35

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

Question 36

capacitive coupling

Answer 36

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

Question 37

avoiding electrosurgical complications in MIS 7

Answer 37

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

Question 38

safety precautions in theatre

Answer 38

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

Question 38

safety precautions in theatre

Answer 38

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

Question 39

duty cycle

Answer 39

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

Question 40

frequency bipolar diathermy

Answer 40

250KHz to 1Mhz

Question 40

frequency bipolar diathermy

Answer 40

250KHz to 1Mhz

Question 41

Gyrus vs TURIS system bipolar TURP

Answer 41

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.

Question 42

harmonic scalpel

Answer 42

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

Question 43

temperatures used in electorsurgery and lasers

Answer 43

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

Question 44

liagsure

Answer 44

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

Question 44

liagsure

Answer 44

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

Question 45

what frequency of current increases risk current leakage to tissues

Answer 45

>3MHz

Question 46

what temp does vapourisation occur

Answer 46

ie. cut is over 200c | coagulation is over 45 degrees

Question 47

bipolar and creation of plasma

Answer 47

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

Question 48

what is diathermy

Answer 48

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

Question 49

why nerves and muscles not stimulated

Answer 49

stimulated at 100khz or below | with such high frequency no time for cell membranes to become depolarised

Question 50

surface area of diathermy plate

Answer 50

70 to 150 cm squared

Question 51

power of cutting vs coag

Answer 51

125-250W | coag is 10-75W

Question 52

how does blend work

Answer 52

only in cutting mode | 50% duty cycle on/off

Question 53

main complications diathermy

Answer 53

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