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Understanding Surgical Diathermy

24 January, 2012 | MedWOW, Surgery Equipment

What is Surgical Diathermy?
Surgical diathermy, also known as electrosurgery, is the passage of a high-frequency alternating current through the body to produce a desirable surgical effect. Despite extensive use, many surgeons and anesthetists remain ignorant of its governing principles and associated hazards. Diathermy involves the deliberate use of electrical energy to produce tissue damage and despite the incorporation of various safety measures, injury to patients still occurs.

Principal Electrosurgical Tissue Effects
The main electrosurgical tissue effects are:
• Electrosurgical cutting divides tissue with electric sparks that focus intense heat at the surgical site. By sparking to tissue, the surgeon produces maximum current concentration. To create this spark, the surgeon should hold the electrode slightly away from the tissue. This will produce the greatest amount of heat over a very short period of time, resulting in vaporization of tissue.
Electrosurgical fulguration (sparking with the coagulation waveform) coagulates and chars the tissue over a wide area. Since the duty cycle (on time) is only about 6 percent, less heat is produced. The result is the creation of a coagulum rather than cellular vaporization. In order to overcome the high impedance of air, the coagulation waveform has significantly higher voltage than the cutting current. Use of high-voltage coagulation current has implications during minimally invasive surgery.
• Electrosurgical desiccation occurs when the electrode is in direct contact with the tissue. Desiccation is achieved most efficiently with the “cutting” current. By touching the tissue with the electrode, the current concentration is reduced. Less heat is generated and no cutting action occurs. The cells dry out and form a coagulum rather than vaporize and explode.
• Many surgeons routinely “cut” with the coagulation current. You can also coagulate with the cutting current by holding the electrode in direct contact with tissue. It may be necessary to adjust power settings and electrode size to achieve the desired surgical effect. The benefit of coagulating with the cutting current is that you will be using far less voltage. Similarly, cutting with the cut current will also accomplish the task using less voltage. This is an important consideration during minimally invasive procedures.

The Electrosurgery Equipment Market
The electrosurgery device market is lucrative and highly competitive. Several surgical diathermy device manufacturers exist, and many creative techniques are used to differentiate products. Some device manufacturers make claims in marketing campaigns that are hard to merge with the laws of physics or basic physiology. The variety of claims may be confusing to surgeons who are investigating the purchase of new electrosurgical products. Understanding a few basic principles of electrosurgery physics can allow a surgeon to be a more informed consumer of electrosurgical products.

Surgical diathermy is an invaluable aid in modern surgery, and most contemporary diathermy machines are considered safe. The literature has proven to be quite meager in terms of reference to complications, although prolonged courses of treatment are required in a number of individual cases.

Injuries and Complications of Surgical Diathermy
The ever-increasing use of high-frequency surgery is a fundamental part of modern-day surgery. Risks and complications are still on the increase, despite the incorporation of various safety measures. The origins of surgical diathermy date back to the discoveries of D’Aversonal in 1893 and Nagelschimidt in 1909, who investigated the effects of the controlled use of high-frequency currents on biological tissue.

As the technique became more widespread, there was a rise in the number of injuries and complications reported and especially, of burns directly associated with diathermy. These were generated by the increasing use, in the interest of patient safety, of other electrical devices, coupled with ignorance of current flow interactions brought about by the associated use of a variety of medical devices. The potential explosion of combustible gases in anesthesia, endogenous intestinal gas, the induction of arrhythmias and the effect on pacemakers as the result of alternating current frequency, create extra risks in electrosurgery.

Additionally, muscle fibers can be activated by the direct electrical stimulation of diathermy and also by blocked motor endplates. This can lead to contraction of the major muscles, which may in turn be misinterpreted as insufficient anesthesia.

The role of diathermy in surgical practice has expanded significantly in recent years. As a result, the patient, surgeon and operation room staff are frequently exposed to hazards such as: burns injury, electrocution, hypoxic stress, inhalation of diathermy plume (also known as diathermy smoke), and gene mutation. However, strict adherence to preventive measures such as proper connection and handling of the diathermy machine, avoidance of inflammable operation room gases, the use of suction device, operation room scavenging system and diathermy plume extraction system significantly reduces the hazards.