Diathermy uses high frequency electric current to generate heat for surgical purposes like coagulation and cutting. While an invaluable surgical tool, it can pose fire and burn hazards if safety precautions are not followed. The main causes of surgical fires are ignition sources like electrosurgical units interacting with fuels like alcohol-based skin preps in the presence of an oxidizer like oxygen. Proper use of diathermy requires checking equipment, applying return electrodes correctly, allowing preps to dry, and avoiding flammable anesthetic gases. Following safety protocols can minimize risks while allowing diathermy to continue enabling beneficial effects in surgery.

1. DIATHERMY AND FIRE
HAZARD IN THE THEATRE
BY
Dr. LAWAL GBENGA
Registrar, dept. of Surgery, NHA
28th October 2016.

2. OUTLINE
• INTRODUCTION
• COMPONENTS / OPERATING PRINCIPLE
• CLINICAL USES
• DIATHERMY AND FIRE HAZARD
• OTHER COMPLICATIONS / HAZARDS
• PRECAUTION / SAFETY
• ALTERNATIVE TO DIATHERMY
• CONCLUSION

3. INTRODUCTION
– Diathermy is derived from the Greek words: Dia - through, therma – heat; thus meaning ‘heating
through’.
– It is a method of elevating local tissue temperature using high frequency electric current,
ultrasound waves or microwave radiation.
• Surgical diathermy is the use of high frequency alternating current to generate deep heat that cause local
tissue destruction (fulguration) or coagulation
• Diathermy is an invaluable facility widely used in the operating theatre, with an ever expanding application in
surgical practice
• Patient, surgeon and theatre staffs are frequently exposed to risks associated with its usage; with grave
consequences if these risks are not mitigated against

4. INTRODUCTION
HISTORICAL PERSPECTIVE
 > 2,000 years - Romans took advantage of heat therapies by building hot spring bath houses.
 300BC - Egyptians used heat for the treatment of tumuor
 1909 - Carl Franz Nagelschmidt - coined the term diathermy and designed a prototype.
 1925 - Dr J.W Schereschewsky – began studying the physiological effects of high frequency
electrical current on animals.
 Bovine discovered that high frequency alternating current could be used to incise or coagulate
tissue to obtain haemostasis.
 1928 - Cushing popularized this technique.

5. COMPONENTS
A. The Generator (Electrosurgical unit {ESU})
• Transforms electricity from mains (50 Hz) into high frequency electrical energy [300kHz
to 3MHz]
• Also allows for variation in frequency and mode setting.
• Fitted with audible & visible alarms.
B. The Active electrode (Diathermy point)
• delivers concentrated current to surgical site.
• Hand operated/foot activated.
C. The Return (Indifferent / dispersive) Electrode
• A contact device.
• Directs electro surgical current back.

6. • The Generator (Electrosurgical unit (ESU)

7. Monopolar electrode

8. Bipolar electrodes

9. OPERATING PRINCIPLE
current
Heat produced concentrated at
active electrode & used for
desired effect
Minimum heat
produced at site of
dispersive electrode
because of its large
surface area
Current goes
back via
dispersive
electrode
generator

10. OPERATING PRINCIPLE
• The frequency of the alternating current from the diathermy generator ranges from 300kHZ-
3MHz.
• Effects within this range are those of heating such that the benefit of burning is obtained
without the harmful effects of electrocution
The amount of heat produced depends on:
• Intensity of current produced by the generator
• Waveform
• Electrical property of tissue via which the current passes.
• Relative size of the 2 electrodes.

11. OPERATING PRINCIPLE
• The waveforms of the radiofrequency currents used in surgical diathermy have been
chosen empirically (i.e. based on observation & experiment).

12. OPERATING PRINCIPLE
• Cutting is achieved by striking an arc between the tip of the active electrode and the
tissue, thus charring it.
• A continuous sinusoidal waveform of high power is most effective.
• Coagulation is best achieved by repetitive burst of few cycles of the current
• Coagulation requires less heat applied over a slightly greater volume of tissue.

13. TYPES OF DIATHERMY
Depends on the number of electrical poles the the site of application.
• Unipolar (monopolar) diathermy
• Bipolar diathermy
Unipolar diathermy - consist of 2 separate electrodes with considerable distance between them
a) active electrode - held by surgeon
b) indifferent (patient) electrode - attached to patient body
• Current passes from the active electrode at the site of surgery to the patient plate on the
patient’s skin.
• Relatively large patient plate is used as the return electrode.
• Heat generated at any point depends on the current density which is high at the small hand held
electrode and low at the large electrode.
• It is used for both surgical dissection & haemostasis.

14. •

15. TYPES OF DIATHERMY
Bipolar diathermy
• Active and indifferent electrodes are in-cooperated in one unit (e.g. diathermy forceps), thus
separated by few millimetres.
• Current passes between the ends of the pair of forceps and via the tissue held within the
forceps.
• Switch built into the forceps is used to activate the bipolar electrodes.
• Heat generated is much less than with monopolar.
• It is more localized and controllable.
• Risk of collateral thermal damage is minimized, and It is safer than monopolar.

17. EFFECT ON TISSUES
A. Coagulation
• This is denaturation of tissue proteins similar to the effect of boiling water on the white of an egg.
• Achieving haemostasis with only a small amount of tissue damage.
• Tissue cells contract, inducing normal clotting.
B. Electrosection – Cutting
• With increase in intensity, an electric arc develops between the tissues and the electrode to
produce a cutting effect used to divide tissues.
C. Fulguration
• this is destructive coagulation of tissues with charring, achieving haemostasis with charring &
deep tissue necrosis

19. USES OF SURGICAL DIATHERMY

20. USES OF SURGICAL DIATHERMY

21. DIATHERMY AND FIRE HAZARD

22. DIATHERMY AND FIRE HAZARD
• Surgical fires are fires that occur in, on or around a patient undergoing a surgical procedure.
• An estimated 550 to 650 surgical fires occur in the United States per year, some causing
serious injury, disfigurement, and even death.
• A surgical fire is perhaps one of the most unique complications of surgery and anaesthesia with
potentially catastrophic threat to the patient.

23. Causes of Surgical Fires
• Surgical fires can occur any time all three of the
following elements are present (FIRE
TRIAD/TRIANGLE) :
• Ignition source (e.g., electrosurgical units, lasers,
and fiberoptic light sources)
• The most common ignition source in operating-room
fires are electro cautery units, and was responsible
for initiating 100% of the fires reported in a recent
literature review
• Fuel source (e.g., surgical drapes, alcohol-based
skin preparation agents, explosive anesthetic gases
[ether, isoflurane],the patient [ mannitol, methane,
hydrogen sulphide]
• Oxidizer (e.g., oxygen, nitrous oxide, room air)

24. OTHER DANGERS / COMPLICATIONS OF
DIATHERMY USAGE
Danger can be to patient, surgeon, assistant and theatre staff.
PATIENT
• Diathermy (thermoelectric) burn
• CHANELLING EFFECT – when used in organs with end arteries or whose vessel are in a narrow
pedicle e.g. penis, digits and testis heat is concentrated in the narrow channel leading to
thrombosis and ischemic gangrene.
(Prevention involves putting the organ in contact with the anterior abdominal wall, using a bipolar
diathermy).
• Infection – overzealous use leads to excessive necrotic tissue which is a good culture medium.
• Secondary haemorrhage – excessive coagulation of vessel >>extensive necrosis of vessel wall
which may slough off >> haemorrhage.

25. DANGERS AND COMPLICATIONS
• poor wound healing – too much coagulation >> tissue ischemia >> delayed wound
healing.
• post operative pain- nv ending exposure, tissue oedema.
• perforation of hollow viscus- it is difficult to control dept of tissue necrosis when using
diathermy to fulgurate growth of hollow organs.
• electrocution – faulty cable.
SURGEON AND ASSISSTANTS
• burns
• electrocution especially when they use perforated gloves.

26. SAFETY MEASURES / PRECAUTIONS
PRE OPERATIVELY
• Do not prepare bowel with manitol
• Shave skin at site for indifferent electrode
• Check equipment regularly
• Alarm systems must be functional
• Staff should understand the mode of operation

27. SAFETY MEASURES / PRECAUTIONS
INTRA – OPERATIVELY
• Prevent patient contact with metal parts of couch and drip stands and away from int.
fixators
• Place active electrode in a quiver
• Allow alcohol disinfectant to dry before use
• Apply indifferent electrode to dry flat skin bearing no scars
• Allow at least 50cm b/w diathermy and anaesthetic machine
• DO NOT USE in the presence of ether
• Choose the appropriate mode
• Monitoring devices and pacemakers-it resets pacemakers firing

28. SAFETY MEASURES / PRECAUTIONS
If ineffective
• Check for faulty connections
• Check the active electrode
• Check indifferent electrode
• Increase power

29. ALTERNATIVES
• LASER
• Less tissue damage
• No smoke produced
• Harmonic scalpel
• Uses USS energy converted to a frequency of 55.5Hz
• No risk of electrocution

30. CONCLUSION
• Diathermy is an indispensable surgical tool facilitates fast, bloodless surgery and reduces
number of sutures & blood transfusion
• Hazards associated with it usage are ever-present; with often grave implications. However, risks
can be kept to barest minimums through a general proactive disposition of theatre staffs, and a
prevailing culture of maintenance and attention to detail.
• Promoting a culture of fire safety in the theatre is not optional. The prevention of surgical fires
with established institutional protocols must be a priority across the professional boundaries in
the operating theatre.

31. REFERENCES
• Haith LR Jr,Santavasi W, Shapiro TK, Reigart CL, Patton ML, Guilday RE, et al. Burn center
management of operating room fire injuries. J Burn Care Res 2012;33:649-53.
• Yardley IE, Donaldson LJ. Surgical fires, a clear and present danger. Surgeon 2010;8:87-92.
• Spigelman AD, Swan JR. Skin antiseptics and the risk of operating theatre fires. ANZ J Surg
2005;75:556-8.
• www.anaesthesiawa.org/fire
• https://www.ecri.org/surgical_fires.
• http://www.fda.gov/Drugs/DrugSafety/SafeUseInitiative/PreventingSurgicalFires/default.htm
• www.fda.gov/Drugs/DrugSafety/SafeUseInitiative/PreventingSurgicalFires/
• http://www.aana.com/resources2/professionalpractice/Pages/Surgical-Fires.aspx
• http://www.patientsafetyauthority.org/ADVISORIES/AdvisoryLibrary/2012/Dec;9(4)/Pages/130.a
spx