Specialized surgical equipment

Terms Associated with Electrosurgery

Apparatus used to deliver electric current to the surgical site.

Current is delivered to the surgical site and returned to the generator by forceps. One side of the forceps is active; the other side is inactive. The current passes only between the tips of the forceps.

Blended current

Current that divides tissue and controls some bleeding.

Coagulating current

Current that passes intense heat through the active electrode used to sear vessels and control bleeding.

Current

Flow of electrical energy.

Cutting current

Current that arcs between tissue and the active electrode to divide tissue without coagulation.

Electrosurgical unit (ESU)

Generator, foot pedal, cords, active electrode, and inactive dispersive return electrode designed to safely deliver electric current through tissue.

Generator

Machine that produces electric current by generating high-frequency radio waves.

Ground

Conducting connection among the generator, the patient, and the earth.

Inactive dispersive return electrode

Apparatus used to return current from the patient back to the generator; also referred to as inactive electrode, return electrode, or patient plate.

Monopolar electrosurgery

Current flows from the generator to the active electrode, through the patient to the inactive dispersive return electrode, and returns to the generator.

Terms Associated with Laser Surgery

Emissions

Surgical lasers emit nonionizing radiation, heat, and debris.

Laser

Acronym for light amplification by stimulated emission of radiation. Light, concentrated and focused, stimulates atoms to emit radiant energy when activated.

Laser beam

Light beams, either pulsed or continuous, go through a medium to produce a lasing effect. The beam has three distinct characteristics:

Coherent

Light beams are sustained over space and time because electromagnetic waves are in the same frequency and energy phase with each other.

Collimated

Light beams are parallel.

Monochromatic

A light beam is one color because waves are all the same length in the electromagnetic spectrum.

Laser plume

Carbonized cell fragments, toxic hydrocarbons, viruses, and noxious fumes can be dispersed from tissues exposed to the laser beam. Vaporization converts solid tissue to smoke and gas. This plume (smoke) is evacuated to maintain visibility and also to minimize the hazard of inhalation by personnel.

Medium

Gases, synthetic crystals, glass rods, liquid dyes, free electrons, and semiconductors are used to produce the lasing effect.

Power

All lasers have a combination of duration, intensity, and output of radiation when wavelengths are activated.

Source

Power to energize the light beam may be electrical, radiofrequency, or optical.

Wavelength

Electromagnetic waves transfer energy progressively from point to point through a medium. The wavelength is the distance traveled along the electromagnetic spectrum. Radiation penetration differs at different wavelengths. Each laser has a different wavelength and color, depending on the medium the light beam passes through.

Terms Associated with Microsurgery

Beam splitter

Attachment to the microscope that splits light; one part is reflected laterally, and the other part is relayed upward to the binocular tube; the percentage can be 50/50 or 30/70. The greater portion may be directed to a camera or video system.

Binocular

Using two eyes to see in stereoscopic vision.

Coaxial illumination

The light path follows the same direction as the visual image.

Contraves stand

Series of weights used to balance some microscopes.

Depth of field

Distance of focus.

Diopter

Power of the lens to assist vision by refractive correction of reflected light.

Focal length

Distance between the lens and the object in focus.

Microscope

Equipment that uses a series of lenses to magnify very small objects.

Monocular

Using one eye for vision. Depth of field is absent; the image is two-dimensional.

Objective

Power of the lens that determines the focal distance of vision.

Ocular

Eyepiece lens that multiplies the basic magnification of the microscope.

Pupillary distance

Measurement between the pupils of the eyes; used to position the binocular eyepieces.

Stereopsis

Vision with two eyes that enables objects to appear three-dimensional.

Working distance

Physical space between the objective lens of the microscope and the surgical field.

Zoom

To change the range of focus in continuous magnification; the change can be closer or more distant.

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Using specialized equipment in surgery

Advances in technology have made possible the complex surgical techniques of the present. Technology may be defined as the branch of knowledge that deals with the creation and use of technical means for scientific purposes. In the context of surgery, technology refers to a system that uses devices as well as people to perform specific tasks. Continuing research will further enhance technology. New devices are usually adjuncts to or extensions of devices or techniques already in use. To enhance their use in patient care, perioperative team members constantly need to learn about new equipment and its applications.

The focus of technology used in patient care is improvement of care beyond human capability. Users of multiple technologic devices in the OR need to be acutely aware of safety. One aspect of safety in this environment is paying attention to the patient as a physical being as well as to the devices used in care. Equipment used in concert with patient care includes but is not limited to the following:

• Anesthesia machine

• Defibrillators

• Monitors

• Sterilizing machinery

• Warming and cooling devices

• Surgical headlights

• Pressurized fluid delivery systems

Before handling new equipment, patient care personnel on the perioperative team should be knowledgeable about its care and use. Some surgical procedures use more than one of these technologies (e.g., laser surgery through an attachment to the operating microscope).

Preparing and handling these expensive pieces of equipment are major responsibilities of perioperative nurses and surgical technologists. In addition, all OR personnel should be aware of and safeguard against hazards associated with equipment. The perioperative environment should be safe for patients and personnel.

Safety points to consider when using equipment in the OR:

• Has the equipment been serviced on a routine schedule?

• Has the equipment had calibration testing?

• Has the equipment been cleaned or processed to the degree of safety for patient use?

• Are the cords and attachments connected properly?

• Are foot pedals in a secure position for safe use?

• Are reusable components in serviceable condition?

• Are disposable components in stock in the appropriate sizes?

• Are adjunct devices and machines in proper working order?

• Are alarms in working order?

• Are power sources available?

• Is the team knowledgeable about the correct sequence for powering up and using the equipment?

• Have policies and procedures for equipment use been developed and provided to the OR team?

All equipment in the OR has an individual asset tag number. The asset number is a combination of alphanumeric figures used to identify the particular unit. When documenting the use of equipment in the OR the identifying number is placed in the patient’s record. Some departments log all asset tags in a master log and assign a simple unit-identifying number or letter that corresponds to the equipment in use. This simplifies documentation.

If any equipment is not in good working order, it must be taken out of service immediately and tagged for repair. It should not put back into service until the biomedical department clears it for use. Some manufacturers will provide loaners when equipment is out for repair. Information on the service tag of malfunctioning equipment should include:

• Name of person reporting

• Date of report

• Description of the problem

• Any other information that may be pertinent

Electrosurgery

Principles of electrosurgery

Electrosurgery is used to a greater or lesser extent in all surgical specialties. Personnel should be familiar with the manufacturer’s detailed manual of operating instructions for each type used. Electric current can be used to cut or coagulate most tissues. Attempts to coagulate large vessels can result in an extensive burn and necrosis. Excess charring and devitalized tissue creates a barrier for wound healing and may provide a medium for infection.

The initial incision is made by a scalpel. The ESU is not used to incise the skin. Electrosurgery can be used on fat, fascia, muscle, internal organs, and vessels. ESUs operate at frequencies between 100,000 and 10,000,000 Hz. This current can be passed through tissue without causing stimulation of muscles or nerves.

Electrosurgery differs from electrocautery. Electrocautery is the use of a unidirectional current generated by a self-contained battery-operated disposable instrument with a wire at the tip. The wire heats when activated and coagulates the tissue. The energy does not enter the patient’s body. The ESU uses an alternating current that passes through the patient’s tissues and returns to the generator. Two forms of ESU generators are commonly used in surgery: monopolar and bipolar. Each type has specific uses and considerations.¹⁰

Monopolar electrosurgery

With monopolar units the electric current flows from the generator to the active electrode, through the patient to a return electrode, and returns back to the generator (Fig. 20-1). The generator returns the current to ground. Any break in the current flow from the generator and back again causes the machine to shut down and sound an alarm as a safety feature.

The surgeon selects the type of current and power setting. The circulating nurse verbally confirms and documents the power settings before the generator is activated. It is seldom necessary to use full-power settings. A safe general rule is to start with the lowest setting of current that accomplishes the desired effect, and then increase the current at the surgeon’s request.

One form of a patient return electrode adhesive pad is placed in direct contact with skin (Fig. 20-2). The contact area must exceed 100 mm² and have a diameter greater than 1.2 cm. The adhesive return electrodes are flexible to mold to the appropriate body surface.

FIG. 20-2 Placement of electrosurgical unit (ESU) patient return electrode.

MEGADYNE manufactures a reusable return electrode, MEGA 2000, measures 720 in² and is not adherent to the patient’s body. This large gel pad is placed in a plastic sheath underneath the bed sheet on the OR bed. The patient makes contact with the pad over most of the contact surface through the bed sheets. This style of return electrode is useful when there is not a suitable site for a disposable return electrode, such as in a burn patient. Positioning in lithotomy can be difficult with this type of electrode. Imaging can be distorted if used under the patient during fluoroscopy. The cord attaches to the generator in the patient return electrode socket.

Electrosurgery causes more patient injuries than any other electrical device used in the OR. Most incidents are caused by personnel error.⁹ Regardless of which return electrode is used, the following safeguards must be followed:

1. The return electrode should be as close as possible to the site where the active electrode will be used to minimize current through the body.

2. The patient should be in the desired position before the adhesive return electrode is applied to prevent its becoming dislodged or buckled during patient positioning. Do not remove or reposition the disposable return electrode because the integrity of the adhesive will be altered. A new electrode is used each time.

3. The return electrode should never be cut to fit.

4. The return electrode should cover as large an area of the patient’s skin as possible in an area free of hair or scar tissue, both of which tend to act as insulation. An area may need to be shaved. The surface area affects heat buildup and dissipation.

Avoid areas where bony prominences might result in pressure points, which in turn can cause current concentration. Place the pad on a clean, dry skin surface over or under as large a muscle mass area as possible. The gel conduction material on the pad is cold and sticky to the touch; a patient who is awake should be forewarned of its application.

5. Any area that overlies an implant is a former surgical site and is not suitable for placement of a return electrode. The return electrode should not be placed on skin over a metal implant, such as a hip prosthesis, because current could be diverted to the implant and generate excessive heat.

6. The integrity of the package of a disposable return electrode should be inspected before use. Do not use the electrode if the package is damaged or has been previously opened.

7. Special care should be taken to ensure that the cord does not become dislodged. Do not put a safety belt over the electrode or cord. The connector should not create a pressure point on the patient’s skin.

8. The connection between the return electrode and generator should be secure and made with compatible attachments. If the return circuit is faulty, the ground circuit may be completed through inadvertent contact with the metal operating bed or its attachments. This is referred to as an alternative pathway for the current.

If the return pad surface area is too small, current passing through an exposed area of skin in contact with metal will create intense heat. For example, one such contact point could be the thigh touching a leg stirrup while the patient is in the lithotomy position. A serious full-thickness burn can occur.

The circulating nurse should record on the patient’s chart the type and/or location of the dispersive return electrode, the condition of the patient’s skin before and after electrosurgery, the generator identification number, and the settings used. Some institutions also require documentation of the dispersive return electrode lot number.

Argon beam coagulator

Argon gas can be incorporated into a monopolar ESU to create a path between the tissue and the active electrode handpiece. The gas is inert and noncombustible and is easily ionized by the electrical current. Argon is heavier than air and creates less plume. The argon-enhanced ESU tip is held at a 60-degree angle and does not contact the tissue during coagulation, thereby causing less tissue damage. The depth of penetration is less than with other forms of monopolar energy.

The active ESU tip and gas stream are passed over tissue to evenly coagulate larger areas. The gas displaces the bleeding over the surface of the target organ. Care is taken not to cause the gas to enter large open vessels because of the risk of gas embolism. Argon-enhanced electrosurgery is a form of monopolar ESU and requires the use of a patient return electrode.

Argon-enhanced electrosurgery is used with caution during laparoscopy. The argon gas adds to the cumulative effect of pneumoperitoneum and overpressurization. Argon is less soluble in blood than CO₂ and could persist long enough to pass to the heart in the form of a gas embolus. One port should be available for venting gases between extended uses of the argon to prevent build up of the gas.

Bipolar electrosurgery

With bipolar electrosurgery the current is directed from the generator to a special forceps with one active tip and one inactive tip. The current flows from the generator to the active tip and returns to the generator through the inactive tip (Fig. 20-3). The energy does not flow through the patient’s body as in monopolar electrosurgery. No return electrode is used. Output voltage is relatively low. This provides extremely precise control of the coagulated area.

FIG. 20-3 Bipolar current path. No patient return electrode is used.

Bipolar electrosurgery is safe to use in cases in which electrical current passing through the body could cause disruption in implantable devices such as pacemakers or internal defibrillators. Because the current does not pass beyond the tines of the forceps the function of peripheral devices remains uninterrupted.⁹

Coblation

Coblators use high-frequency bipolar energy in a conductive medium to create a highly focused plasma field.¹⁰ The energy is passed through a flow of saline irrigation to cause a field of highly charged electrons to break the molecular bonds of the target tissue while preserving the integrity of surrounding healthy tissue. The saline is conductive, causing a vaporized plasma field the thickness of a sheet of paper. The temperature does not need to reach extremes of thermal effect as in other coagulation devices to separate the tissues. The average temperature is only 20° C to 40° C compared with 200° C to 400° C.

The tip of the wand instrument is 1 to 2.5 mm wide with two tiny electrodes through which the saline is passed over the target area.³ Coblation was originally designed for use in arthroscopy, but later found favor with otorhinolaryngologists for nasal and tonsil procedures.⁸ In oral and nasal tissue procedures the greatest limitation is in sinus procedures, where a bony obstruction may be encountered.¹³ Plastic surgeons have been working with coblation as a tool for skin resurfacing for deep acne scars and facial wrinkles. Coblation offers an alternative to chemical peels and laser surface modifications.⁵

Generalized safety factors for the use of electrosurgery

Electrical burn through the patient’s skin is the greatest hazard of electrosurgery. These burns are usually deeper than flame burns, causing widespread tissue necrosis and deep thrombosis to the extent that debridement and grafting may be required. Not all deep thermal injury is immediately apparent.

In addition to the precautions noted for preparing the ESU and for positioning the dispersive return electrode used with monopolar units, other precautions should be taken as follows:

1. Electrosurgery should not be used in the mouth, trachea, around the head, or in the pleural cavity when high concentrations of oxygen or nitrous oxide are used.¹ During some procedures such as eye surgery, oxygen is administered via nasal cannula or mask. Oxygen builds up under the drapes and sets the stage for a combustible situation. Flame-retardant drapes can conceal a fire in a confined space. Safety regulations for use with all inhalation anesthetic agents are followed.