Electrosurgery and Electrosurgical Units
Electrosurgeries are surgical procedures which employ a high-frequency alternating current while operating over a tissue. This method is more commonly utilized in surgeries where precision is important and blood loss needs to be minimized. To achieve this, an electrosurgical unit is needed.
Machines like Valleylab Force FXc are a common sight in most hospitals’ surgical wards. These machines are known as electrosurgical units. Conceptualized and invented by an American scientist, William Bovie, the electrosurgical units are also commonly known as Bovies or Bovie machines.
Electrosurgical units are high-frequency alternating current generators. They are used in different kinds of surgeries where soft tissue is required to be cut, coagulated, dissected or shrunk. They are capable of producing different kinds of high-frequency alternating currents and waveforms depending on what task needs to be achieved.
The process requires that the high-frequency current be passed through the tissue that is being operated. This heats up the tissue, resulting in coagulation or complete evaporation of the tissue fluid. The tissue can be heated up to any temperature between 60 degrees Celsius (140 degrees Fahrenheit) to 100 degrees Celsius (212 degrees Fahrenheit), depending on the requirements. These units are also used if internal bleeding occurs, passing the current through the area coagulates the blood, stopping the blood.
Electrosurgical units have advanced over a period of time and are very commonly used in a lot of different surgical areas. From dermatological uses to neurosurgery options, many fields employ their use. Electrosurgical units in dental surgeries are also being observed nowadays, however, not as common as in the other surgical disciplines.
Types of Electro-surgeries
Based on what kind of electrosurgical unit is being utilized, these surgeries can be classified into two subcategories:
- Bipolar Electrosurgery
- Monopolar Electrosurgery
The two are differentiated based on the electrodes present in the machine. These determine what path the high-frequency current would take through the body, or affected tissues in particular.
Bipolar Electrosurgery
Bipolar electrosurgery is where the return path for the current is through the tissue and back to the return channel from the tissue. Both the electrodes, one for sending the current and the other for receiving the current, are placed at the tissue that is being operated. This way the patient does not require any additional return electrode and the current does not flow through any other part of the body. This type of electrosurgery is often performed when coagulating a certain fluid within the body or the tissue.
Monopolar Electrosurgery
In monopolar electrosurgery, the current path is very different from the bipolar electrosurgery. The current is introduced at the tissue by an electrode, however, the returning current does not flow back through the same site. Rather the current flows through the body to another electrode that is placed on a patient’s body, away from the site of operation. This often leaves a burn mark on the patient’s body, since the current passing through the body faces resistance and generates heat. However, this can be overcome by keeping in mind the return electrode specifications and the current provided.
Testing the Electrosurgical Units
It is crucial to realize that electrosurgical units need to be handled with care. Otherwise, they can prove to be a hazard. Before using these units, testing these units should be a regular practice to avoid any fatal mistakes during the surgery.
The first priority for performance testing of these electrosurgical units should be to look for manufacturers recommended tests. These tests can best judge a device’s performance and also avoid any damage to the device while testing it. However, in case the manufacturer’s manual is not available, here are some ways you can test the performance of your electrosurgical unit.
Output Supply Testing
Otherwise known as power tests, these tests are observed at the output signals of an electrosurgical unit. They determine whether the output power at the electrodes is at the rated value. Moreover, the output current, voltage, and crest factors are also tested for different loads to ensure that the machine is working properly.
By testing the output on different kinds of loads, it is ensured that the unit responds to the different impedance’s that it comes across. The standard values for different loads should be checked in the user manual or other sources to determine whether or not the device is working correctly. The output values can lie in between the margin of +- 5% of the rated value, however, the least deviation is preferred.
Most of the new electrosurgical units come with built-in testing capabilities. This way you can have a quicker output power test on your machine. The impedance circuitry is provided with in the machine. You can simply run the testing sequence and check for the values. Otherwise, you will have to provide different impedance’s at the electrodes.
Current Leakage Testing
The high-frequency alternating current poses a threat to safety. At high frequencies, the current tends to couple capacitively with other conductive materials. If there is a large amount of leakage current present in the unit, this can harm the operator as well as the patient. Often burn marks are observed due to negligence in checking leakage currents. The damages can be much more severe; it is important to have the equipment tested beforehand.
There are standards set by the IEC for the safe use of electrosurgical units. These standards dictate that the leakage current should not be more than 150 mA through a 200 ohms load to the ground. This testing is conducted on all the electrodes present in the device.
A simulation is set for the device where the electrodes are treated as faulty. The unit’s response is then observed, the electrosurgical unit must shield from any kind of leakage that exceeds the standard.
Return Electrode Current Monitoring Test
Return electrode monitoring test is also a crucial test that ensures that the device is working properly and avoids any major mishap during the surgery. Electrosurgical units are equipped with alarms, they can be audio, visual or both. These alarms go off in case the current flowing through the return electrode increases from the set threshold. In addition to the alarm going off, the generator must also immediately turn off.
This test can be done using standard impedances and increasing the value for return electrode current. Typically, the values of these standards are provided by the manufacturer in the device manual.
Conclusion
When operating with high-frequency alternating currents, it is imperative that all these tests are carried out beforehand. A faulty electrosurgical unit can lead to serious injuries to both the patient and the surgeon. With the help of these tests, you can ensure the safe use of these devices.