2-daithermy fni$

7/30/2019 2-DAITHERMY fni$

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High Frequency Heat Therapy

*physical stimulus employed of physiotherapyis in the form of heat, either by simple heatradiation or by the application of high frequencyenergy obtained from special generators.

*The use of high frequency energy inthermotherapy has the advantage ofconsiderable penetration as compared with

simple heat application.


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High Frequency Heat Therapy

*Thus with high frequency energy ,dipper

lying e.g., muscles, bones, internal organs,ect.Can provide heat.

*High frequency heat therapy is based on thebased on the fact that the dipole molecules ofthe body are normally placed randomly under theinfluence an electrical field


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*they rotate according to the polarityof their charge

*in the direction of the field theyrotate according to the polarity of theircharge in the direction of the field lines


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*The positively charge end of thedipole then orients itself to the minus

pole and the negatively end to the pluspole.*Since the polarity of the electric

field alternates, a micro-heatingeffect results from the continuous re-alignment of the molecules. Highfrequency energy for heating isobtained by various ways.


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*It may be from the short-wave therapyunit making use of either the condenser fieldor the inductor field method..*Microwaves and ultrasound waves are alsoused for heating purposes in special cases.


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WHAT IS ELECTROSURGICAL DIATHERMY

?

*Electrosurgery defined as the use of radiofrequency electric curent to sever tissue or

achieve hemostasis.*A high frequency is used because a lowfrequency (below 100,000 Hz) will stimulatenerves or in other words can electrocute thepatient .


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* Medical diathermy is similar toElectrosurgery in that a radio frequency

current is passed through the patient body.Entry and exit electrodes are chosen sothat tissue heating is never high enough tocause necrosis.

*Typically electrosurgical generators canoperate at frequencies up to 4 MHz, atthese frequencies reactive phenomenon

(capacitance and inductance) become quiteprominent. Therefore some famous modelslike VALLEY LAB SSE2K

operate at 500 kHz.


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There are three surgical effects which can beachieved by Electrosurgery :

*ELECTROSURGICAL DESSICATION

(low power coagulation with out sparking).

* ELECTROSURGICAL CUTTING

(electric sparking to tissues with cutting effect).

* ELECTROSURGICAL FULGURATION

(electric sparking to tissues without cuttingeffect).

SURGICAL EFFECTS OF DIATHERMY:-


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CONTROLPANEL

FOOT

SWITCHPOWER

SUPPLY

POWER

OUTPUT BOARD

AUDIO TONE

GENERATOR

LOGIC

BOARD

ISOLATIO

N SWITCHBOARD

BLOCK DIAGRAM OF SURGICAL DIATHERMY


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ELECTROSURGICAL DESICCATION:-

*In desiccation electric current is passedthrough the electrical resistance of tissueand heat arises in the tissue.

*when the tissue becomes hot water is drivenout of the tissue Visually during desiccationtissue becomes brown then it steams as thewater is driven out.*SSE 2K can perform desiccation with

either BLEND , CUT or COAG.


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ELECTROSURGICAL CUTTING:-

*In electrosurgical cutting objective is to heat thetissue so rapidly that cell explodes into steam,leaving a cavity in the cell matrix .

*The heat is dissipated in the steam and ,

therefore it does not conduct through the tissue todry out adjacent cells.

*When the electrode is moved and fresh tissue iscontacted , new cells are exploded and the incision

is made .*When the radio frequency current jumps across

the air gap to tissue .


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*The bright light in the air gap is

technically calledspark

.*An ARC is a similar phenomenon which

requires longer intervals to becomeestablished .

Electrosurgical cutting involves sparkingto tissue .*A hot cattery wire ( a heated wirewith no electric current ) can also cut

the tissue by the mechanismexplained above)


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*The essential characteristic of CUT is that

they are continuos sine waves . That is if thevoltage is plotted over time a pure CUT waveform is a continuos sine wave at 500 kHz


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ELECTROSURGICAL FULGURATION:-

*COAG wave form generally consists of shortbursts of radio frequency sine wave.*The frequency is 450 kHz and the bursts occur at20,000 times/second .

*the average power delivered in a COAG wave is lessbecause it is turned off most of the time .

*A good COAG wave form without significant cuttingeffect because the heat is more widely spread by

the long sparks and because the heating isintermittent.


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*The temperature of water in the cellsdoes not go high enough to flash into

steam, in this way cells are dehydratedslowly and are not torn apart to form anincision .*Some times desiccation and fulguration arethought to be same , Fulguration can becontrasted with desiccation in several ways

..first, sparking to tissue always producesnecrosis, whereas desiccation may notproduce necrosis.


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Typical current = 0.5 Amp. Electrode in good contact

with the tissue.

Deep coagulation.

Spreads rapidly. Relatively soft,light brown

eschar.


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Typical current 0.1 Amp.

Electrode free from tissue.

Long sparks result insuperficial coagulation

Deeper necrosis asfulguration continues.

Eschar is hard and black.


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Typical current 0.1 Amp.

Electrode is separated fromtissue by a thin layer ofsteam.

Small intense sparks flashcells into steam.

Hemostasis can be minimal.


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*When using monopolar electrodes, a patientreturn is always required because it provides amean for the current to leave the patients bodysafely and return to the generator.

*The patient return electrode must be

considerably larger than active electrode so thatthe current density is kept low and nosignificant heating occurs.

* This return electrode is referred to as patientreturn electrode and not ground plate

because there is a confusion which might makepeople to assume that it is convenient

goring for ECGs or other purposes.

PATIENT RETURN ELECTRODE:-


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FOOT SWITCH


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Short -Wave Diathermy

*The term of *diathermy* means throughheating or producing deep heating directly inthe tissues of the body.

*Externally applied sources of the heat likehot towels, infrared lamps and electricheating pads ,often produce discomfort andskin burns long before adequate heat haspenetrate to the deeper tissue.


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*But with the diathermy technique, thesubjects body becomes a part of the

electrical circuit and the heat is producedwithin the body and not transferredthrough the skin. , Another advantage ofdiathermy is that treatment can becontrolled precisely.

*Careful placement of the electrodes

permits location of the heat to the regionto


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,*that has to be treated the amount of heat

can be closely adjusted by means of circuit

parameters.*the heating of tissues is carried out byhigh frequency alternating current whichgenerally has a frequency of 27.12KHz and

the wavelength of 11m.

*Currents of such high frequencies do not

stimulate motor or sensory nerves, nordo they produce any muscle contraction.Thus


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*when a such a current is passed throughthe body, no discomfort is caused to

the subject.

*The current being it is possible to pass

through the tissue currents of a muchgreater intensity to produce directheating in the tissues similar to any otherelectrical conductor.


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*The method consist in applying the out

put of a radio (RF) oscillator to a pair

electrodes which are positioned on the bodyover the region to be treated.

*The RF energy heats the tissues andpromotes heating of injured tissues andinflammations.


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The short wave diathermy machineconsists of two main circuits

*Oscillating circuit: which produced highfrequency current.

*Patient circuit: which is connected tothe oscillating circuit and through whichthe electrical energy is transferred tothe patient.


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Application technique of short-wavetherapy:

*The pattern of tissue heating is generallyaffected by the method of short-wave

diathermy delivery.

*The two most common forms of applicationinclude the capacitor plate method and the

inductive method.


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*In the capacitor plate method, the out

put of the short-wave diathermy machine is

connected to metal electrodes which arepositioned on the body over the region to betreated.

* This electrodes called *PADS* in theterminology of the diathermy.

Application technique of short wave


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Application technique of short-wavetherapy:

*These pads or electrodes do not directlyconnect with skin. Usually layers of towelsare interposed between the metal and the

surface of the body.*The pads are placed to that portion of thebody to be treated is sandwiched betweenthem. This arrangement is called the


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*Condenser Method* wherein the metalpads act as two plates while the body

tissues between the pads as*dielectric* ofthe capacitor

.


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*When the radio frequency out put isapplied to the pads, the dielectric

losses of the capacitor manifestthemselves as heat in the interveningtissues.

*The dielectric losses may be due tovibration of ions and rotation of manifestin the tissue fluids (electrolytes) andmolecular distortion in tissues which are

virtually insulators like fat


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*Alternatively, the output of thediathermy machine may be connected to

a flexible cable instead of pads. Thiscable is coiled around the arm or knee orany other portion of the of the bodywhere plate electrodes are inconvenient

to use


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*When RF current is passed throughsuch a cable ,an electro static field isset up between its ends and a magneticfield around its centre.

*Deep heating in the tissue results from

electrostatic action whereas the heatingof the superficial tissues is obtained byeddy currents set by a magnetic effect.

This technique is inductothermy.


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*Although most of the short-wave

diathermy machines have an out putpowerControl, yet there is no indication of theamount of converted and absorbed heat

within the body tissues.*Therefore ,the intensity of treatment isdependent on the sensation of warmthfelt by the patient.


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Microwave diathermy

*This type consist of in irradiating the

tissues of the patients body with veryshort wireless waves having frequency inthe microwave region.

*Microwaves are a form of electrodesmagnetic radiation with a frequency rang of300-30,000MHz and wave length varying

from 10mm to 1m.


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*The most commonly used microwavefrequency for therapeutic heating is

2450Mhz corresponding to a wavelengthof 12.25 cm.

*microwavediathermy provides one ofmost valuable sources of therapeutic

heat available to the physician


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Microwave diathermy

*Effect of microwave diathermy are similar

to short-wave yet in other better resultare obtained by using microwave.

*The technique application of microwavediathermy is very simple. Not likeshortwave


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* the pads are used tobring in thepatient as a part of the circuit, themicrowave are transmitted from anemitter, and are directed towards theportion of the body to be treat.

*Thus no tuning is necessary forindividual treatments These waves passthrough the intervening air space and areabsorbed by the surface of the body

producing the heating effect.


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*such currents produced by special typeof device called*magnetron* is used for

the production of high frequency currentsof high power.

*The magnetron consist of cylindricalcathode surrounded by an anodestructure that contains cavities openinginto the cathode-anode space by mean

slots.


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*the out put energy is derived from theresonator system by means of a coupling loop

which is forced into one of the cavities.*The energy picked up on the coupling loop iscarried out of the magnetron on the central

conductor of a co-axial out put tube througha glass seal to a director which consist ofradiating element of antenna and a reflectorwhich directs the energy for application to

the patient


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*The electrical current is transformedinto electromagnetic radiation on passing

through the antenna.

*The reflector then focuses thiselectromagnetic energy and beams intothe where subsequence absorbed,reflected or refracted, according to theelectrical properties of the tissue


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*Tissues of lower water content arepenetrated to greater depth by this

little is absorbed, whereas tissues ofhigh water content absorbedelectromagnetic energy but allow littlepenetration.

*the out put powermagnetrondependsuponanode voltage, magnetic field andthe magnitude and phase of the loadimpedance to which the magnetron output power is delivered.


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*Therefore the cable used to carry theenergy from the magnetron to thedirector is always of a define length for aparticular frequency.

*A part of the energy fed to the

magnetron is also converted into heat inthe anode on account of the collision ofthe electron with the anode so that theout put energy is considerably less thanthe input energy.


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Repair Tips

Problem*No Output in any mode.*Output Coagulation OK No Cut.

*Cut OK no Coagulation.

*Hand control OK Foot switch notworking.

*Machine at no response.

*Low output in Cutting OR CoagulationMode.


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Causes of these Problems

No Output in any Mode:Pencil Error.Power Driver may be faulty.Fault in RF board .

Output Coagulation OK No Cut:Fault in Pencil/foot paddle.Iso-block board must be checked.Multi-vibrator board may have some error.

Output relay in the main board may notworking properly.


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Causes of these problems

:Cut OK No CoagulationFault in Pencil/foot paddle.Iso-block board must be checked.Multi-vibrator board may have some error.

Output relay in the main board may notworking properly.Hand control OK Foot switch not working.

Foot switch connector damage.In continuity in the wires of paddle.


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Causes of these repairs

Machine at No response.

Error in Power switch.Problem in power board.

Problem Cooler assembly.

Low Output in Cutting or Coagulation mode.Fuse may be open.

May be fault of Power Transistor.

Rust on Patient Plate.


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