Electrocautery December 4, 2009Posted by casaadelina in other procedures, services.
Cauterization is a medical term describing the burning of the body to remove or close a part of it. The main forms of cauterization used today are electrocautery and chemical cautery. Cautery can also mean the branding of a human, either recreational or forced. Accidental burns can be considered cauterization as well.
Cauterization in the Past
Hot cauters were applied to tissues or arteries to stop them from bleeding. The verb to cauterize; known in English since 1541; from Medieval French cauteriser; from Late Latin cauterizare “to burn or brand with a hot iron in the rectal area”; itself from Greek kauteriazein; from kauter “burning or branding iron”; from kaiein “to burn.”
Cauterization was used to stop heavy bleeding, especially during amputations. The procedure was simple: a piece of metal was heated over fire and applied to the wound. This would cause tissues and blood to heat rapidly to extreme temperatures in turn causing coagulation of the blood thus controlling the bleeding. The downside was extensive tissue damage. Later special medical instruments called cauters were used to cauterize arteries. Abulcasis and later Ambroise Paré introduced the technique of ligature of the arteries in lieu of cauterization.
Electrocauterization (also called electric surgery or electrosurgery) is the process of destroying tissue with electricity and is a widely used technique in modern surgery. The procedure is frequently used to stop bleeding of small vessels (larger vessels being ligated) or for cutting through soft tissue i.e. abdominal fat in a laparotomy or breast tissue in a mastectomy.
Electrosurgical Generator (ESG)
The ESG is the power force behind an electrosurgical system providing the frequency, the voltage, and may modify the electical wave to allow for cutting versus coagulation.
To prevent Electric shock, an alternating frequency that is higher than power from standard wall outlets is used. Normal “house-current” AC runs at 50-60 Hz and is quite lethal, since at every alteration nerves and muscles get stimulated, causing violent cramps 50-60 times a second. However, nerve and muscle stimulation cease at 100,000 Hz due to alterations being too fast for the cells to pick up. Electrosurgery can be performed safely at “radio” frequencies above 100 kHz.
Cutting vs. Coagulation
Different cauterizing effects can be achieved by changing the voltage of the current as well as the pattern of electric pulses. When lower voltage is used with a continuous AC current, heat is produced very fast and tissue is completely vaporized at the tip of the probe. The effect is dubbed “cutting”. When a higher voltage current is used in a pulsed manner, heat is produced more slowly, tissue damage is more widespread (a few mm from the probe) and blood coagulates, and in many electrosurgery instruments this is called “coagulation” mode). This is also used for ablation. Usually a “blend” setting is available as well.
Monopolar vs Bipolar
Two kinds of electrocautery are used, unipolar and bipolar (aka. monothermy and diathermy, respectively). Both involve high frequency alternating current and a pair of electrodes, one called active and the other returning. The difference lies in the placement of these electrodes:
Monopolar: Current is passed from the probe (active electrode) where cauterization occurs and the patient’s body serves as a ground. A grounding pad (returning electrode) is placed on the person’s body, usually the thigh, and it carries the current back to the machine. Careful application of the patient return electrode is necessary as if the electrode is not correctly attached extensive burns can occur undetected.
Bipolar: The active and receiving electrodes are both placed at the site of cauterization. The probe is usually in the shape of a forceps, each tine forming one electrode, and only the tissue grasped by them is cauterized.
The cautery probes are shaped in a variety of ways depending on their purpose. A common monopolar probe is penshaped but ending in a small slender spatula, roughly 5 mm X 30 mm. The shape is reminiscent of a scalpel. This can serve both as a coagulator and as an electric scalpel. The typical bipolar probe resembles a pair of tweezers, which are used to grab a hold of a small piece of tissue and cauterize it. Variants of these probes are used both in open surgery and in modern minimally invasive surgery. The surgeon operates the probe either by pushing a button on the shaft of probe itself or by using a footpedal.
When using monopolar electrocautery it is important that the grounding pad be the only way by which the current passes through the body. Electricity always follows the path of least resistance, and if that is via some ground-connected piece of metal touching the patient by chance, a burn might result there as well as at the tip of the cautery probe. Thus great care must be taken that the patient be insulated from the ground and that the large grounding pad be thoroughly attached to the patient. Further defects in insulation of the monopolar instrument and capacitive coupling can lead to trauma to non-target tissue.