Applications in General Surgery

Lasers and light source technologies have been applied to a wide variety of open and laparoscopic procedures in general surgery and other disciplines.

The ability to produce highly precise and controllable effects on tissues, and the potential to facilitate complex dissection make these devices a welcome addition to the armamentarium of the surgeon.

Each laser wavelength has a characteristic effect on tissue and it is the combination of the laser tissue interaction and the selection of the appropriate delivery systems and laser parameters that determine the ultimate effects of laser use during surgery.

This chapter will review the array of laser technologies available for both open and laparoscopic surgical use and will discuss the relative merits and disadvantages of each.

Introduction

A wide variety of lasers and light-based sources are available for use in both open and minimally invasive surgical procedures.

Proper selection of wavelength, delivery devices, and the use of appropriate surgical technique provides several advantages in the care of the surgical patient.

Proper use can reduce blood loss, decrease postoperative discomfort, reduce the chance of wound infection, decrease the spread of some cancers, minimize the extent of surgery in selected circumstances, and result in better wound healing, if they are used appropriately by a skilled and properly trained surgeon.

The general surgeon encounters a wide and varied array of clinical conditions and operative scenarios in daily practice.

Many different surgical skills and modalities are required to achieve acceptable outcomes for the patient.

There are oftentimes several treatment options and surgical procedures that are equally efficacious for a particular disease process.

Any surgical procedure can be performed using lasers.

General surgeons use a wide variety of laser wavelengths and laser delivery systems to cut, coagulate, vaporize or remove tissue.

The majority of “laser surgeries” actually use the laser device in place of other instruments to accomplish a standard procedure.

Lasers are used in both contact and non-contact modes depending on the wavelength and the particular clinical application. These devices are interchangeable to some degree, assuming that the proper delivery device and laser parameters are selected.

Lasers have occupied the fancy of the lay public, scientists and clinicians alike. These technologies have been applied to a wide variety of open and laparoscopic procedures in a variety of disciplines including general surgery.1–85 The ability to produce highly precise and controllable effects on tissues, improved hemostasis, easy adaptability to fiberoptic and minimally invasive delivery systems, and the potential to facilitate complex dissection make these devices a welcome addition to the armamentarium of the surgeon.

The general surgeon encounters a wide and varied array of clinical conditions and operative scenarios in daily practice. Many different surgical skills and modalities are required to achieve acceptable outcomes for the patient. There are oftentimes several treatment options and surgical procedures that are equally efficacious for a particular disease process. One need only consider the options available to treat breast cancer as an example of this phenomenon. Surgeons often differ as to what particular instruments are the most useful during the conduct of specific technical aspects of surgical procedures. While the motto of the Stanley Tool Corporation (Bridgeport, CT.) “The right tool for the right job” is apropos; surgeons will differ in their definition of the right tool. Such decisions are often based on preference rather than on necessity. Any surgical procedure can be performed using lasers. However, there are no general surgical procedures for which the laser is sine qua non.

General surgeons use a wide variety of laser wavelengths and laser delivery systems to cut, coagulate, vaporize or remove tissue. The majority of “laser surgeries” actually use the laser device in place of other tools such as scalpels, electrosurgical units, cryosurgery probes or microwave devices to accomplish a standard procedure like mastectomy or cholecystectomy.2–57 Lasers allow the surgeon to accomplish more complex tasks. Proper use can reduce blood loss, decrease postoperative discomfort, reduce the chance of wound infection, decrease the spread of some cancers, minimize the extent of surgery in selected circumstances, and result in better wound healing, if they are used appropriately by a skilled and properly trained surgeon. They are useful in both open and laparoscopic procedures. Lasers are used in both contact and non-contact modes depending on the wavelength and the particular clinical application. These devices are interchangeable to some degree, assuming that the proper delivery device and laser parameters are selected. However, the visible light and Nd: YAG lasers should not be used for skin incisions, since they are less efficient than the carbon dioxide laser and result in excessive thermocoagulation of the wound edges.

Laparoscopic cholecystectomy can be credited with fueling a revolution in surgical thinking and application. Surgeons initially had an intense interest in lasers and laser technology for use during laparoscopic cholecystectomy.3,4,9,16–19,21–28 Nearly 80% of all cholecystectomies performed in the United States during 1992 were performed laparoscopically, with only 4% being performed with laser technology.

The majority of general surgeons rapidly discarded “the laser” for electrosurgical devices and “conventional” instruments as they grappled with mastering new techniques and procedures with unfamiliar laparoscopes, video cameras and skills which they had never seen or used previously. The initial enthusiasm and interest in the use of lasers in minimally invasive surgery from the general surgeon’s perspective can be traced to the work of Reddick, Schultz, Saye and McKernan.20,22–26 It must be understood however that the advent of video endoscopy, specific laparoscopic instrumentation for cholecystectomy and other procedures along with the development of multiple-load endostaplers have done much to simplify minimally invasive surgery for the skilled laparoscopist.

This chapter will review the array of laser technologies available for both open and laparoscopic surgical use and will discuss the relative merits and disadvantages of each.

Lasers Versus Other Technologies

Advantages of other technologies

Electrosurgical devices are much more familiar, ubiquitous in the operating room.

Capital equipment expenditures are less for many of these devices and some disposables used with them.

These devices are “faster” since the surgeon is much more conversant with electrosurgical technology and its appropriate application.

The main advantages of electrosurgical devices are the ubiquity of them in the operating room and the fact that no additional training or safety considerations need be implemented.

These factors, when coupled with the average surgeon’s comfortability with using them, make them the technology of choice for many surgeons. devices.

Disadvantages of electrosurgical devices

The main disadvantages of electrosurgical devices rest on the relative imprecision of the delivery of energy to the desired target.

The build-up of char and debris on the electrode surface can result in the delivery of energy to areas adjacent to the desired target rather than to the target itself.

Electrosurgical devices work poorly in the presence of blood, edema and irrigating solutions.

The majority of insulated laparoscopic hand instruments have relatively large exposed electrode surfaces. A large electrode may result in damage to adjacent structures.

Capacitance coupling can occur with monopolar devices.

The tips of bipolar or harmonic scalpel devices can become hot during use and can damage tissues contacted after use.

Advantages of laser technology

Disadvantages of laser technology

Opponents often cite the acquisition expense of laser machinery and accessories in addition to an increased operative time as the main disadvantages of lasers.

Additional training and attention to safety are necessary.

One must consider whether any laser adds anything to the surgeon’s armamentarium. Electrosurgical devices are much more familiar, ubiquitous in the operating room, “less expensive” from perspective of capital equipment expenditures and for some disposables, and “faster” particularly since the surgeon is much more conversant with electrosurgical technology and its appropriate application. Other alternatives including bipolar cautery and the harmonic scalpel are becoming increasingly popular alternatives to both monopolar cautery and lasers. The skills required to use these newer technologies are also more easily acquired since they are closely akin to the repertoire of the surgeon.

The main advantages of electrosurgical devices are the ubiquity of them in the operating room and the fact that no additional training or safety considerations need be implemented. These factors, when coupled with the average surgeon’s comfortability with using them, make this the technology of choice for many surgeons.2–13,16–21,28 Both monopolar and bipolar instrumentation is available for both open and laparoscopic use and the majority of “routine” laparoscopic instrumentation is insulated to permit their use with electrosurgical devices. The main disadvantages of electrosurgical devices rest on the relative imprecision of the delivery of energy to the desired target. The build-up of char and debris on the electrode surface can result in the delivery of energy to areas adjacent to the desired target rather than to the target itself. Electrosurgical devices work poorly in the presence of blood, edema and irrigating solutions. The majority of insulated laparoscopic hand instruments have relatively large exposed electrode surfaces. A large electrode may result in damage to adjacent structures, particularly in close spaces. Capacitance coupling is also a potential problem. Bipolar devices and harmonic scalpels avoid the issues of stray current injuries. However, the instrument tips can become hot during use and can damage tissues contacted after use.

An array of laser technology is available for use during laparoscopy for incisional purposes. Currently, this includes the argon, CO₂, holmium, KTP and Nd: YAG lasers. More recently, high power diode laser technology has become available for use in soft tissue applications. New entrants in this arena are likely. Laser technology is also available for lithotripsy. We will discuss each of these wavelengths and technologies in some detail below. Several points bear mention prior to the consideration of specific technologies.

Proponents of laser technology list the high degree of precision possible with these devices and the ability to control the tissue effect at the desired target as being the main advantages of these devices.3–6,9,10,16–34 Opponents often cite the acquisition expense of laser machinery and accessories in addition to an increased operative time as the main disadvantages of lasers in general. Although these issues are often raised, few recognize that the “cost” of a technology is not necessarily correlated with the actual price of the technology and that the price has little to do with the charge or the reimbursement. It must be understood that the net or global effect of a technology may be to lower the total cost of an illness when one considers factors such as the length of hospitalization, the degree and length of disability and the ability of the patient to return to normal productivity.

Surgical “speed” evolves and improves and the “length of the procedure” declines after the “learning curve” and once the surgeon becomes experienced and facile with the technique and the technology used to accomplish a procedure. It should be recognized that a laser may be used for only a small portion of a procedure and several other factors also impact the operative time.

The surgeon should have a complete working understanding of lasers, their delivery systems and their tissue effects prior to attempting to apply them to laparoscopic or other procedures. The surgeon should attend specific hands-on laser training programs if laser education and the opportunity to use these devices during the course of an approved residency training program were not available or if the surgeon is not familiar with a particular device or delivery system. Clearly, the house officer is in the ideal position to acquire the intellectual and manual skills necessary to use lasers and other technologies properly if this opportunity is provided as a part of the residency training program. Postgraduate continuing medical education programs are useful for those who did not have formal training elsewhere. It is imperative that the surgeon continue to develop these newly acquired skills in an ongoing, graded fashion. This requires the gradual incorporation of the use of laser technology into clinical practice by tackling the simpler procedures and tasks first, followed by more difficult problems later, after the surgeon has developed a sense of comfortability with the technology. One should have a working understanding of the limits and advantages of lasers in one’s own hands. The surgeon must be aware that all lasers and delivery systems are not alike and that attention to the selection of the proper wavelength, the proper delivery system and the proper laser parameters are central to achieving the desired clinical endpoint given the appropriate technical expertise.

The above point cannot be neglected by the surgeon. The selection of a laser device, delivery system or any other instrument during the course of a procedure is critical to the conduct and outcome of that procedure. The selection of instrumentation for procedures involves a number of variables as we have already discussed. However, the preference of the surgeon is a major determinant in this process. Preference depends on availability, skill, judgment, experience and the sense that a particular tool “feels right” or “works well” for a particular task in the hands of a particular surgeon. One needs only to examine the back table during an operative procedure to realize that several alternatives exist for the surgeon’s execution of a particular task.

Laser Characteristics/General Considerations

Adequate preoperative patient evaluation and education.

Antibiotic prophylaxis as indicated.

Several different laser wavelengths and laser delivery systems are available for use during surgery.2–57 Each laser wavelength has a characteristic effect on tissue and it is the combination of the laser tissue interaction and the selection of the appropriate delivery systems and laser parameters that determine the ultimate effects of laser use during surgery. This presumes that the surgeon has the appropriate skill and technique. Thus, it is possible to precisely select and control the degree of tissue injury during surgery.

The ability to achieve the desired effect on the target tissue is also dependent on the surgeon’s understanding about the relationship between Power Density (PD) and the laser tissue interaction. Power density represents a concentration function and is defined as:

$PD=Power/p*{r}^{2}=W/c{m}^{2}$

The power is the selected output power of the laser given in watts and r represents the radius of the beam’s spot. It can be seen that given this relationship, the spot size or beam diameter has a significant influence on the power density relative to a given power output of a laser. The length of exposure of a target tissue to the laser energy is the fluence that is measured in Joules per centimeter squared and which is defined as follows:

$\begin{array}{c}FLUENCE=(Power/p*{r}^{2})\text*\text(\text{time in seconds}) =W\mathrm{sec}\text/c{m}^{2}=J/c{m}^{2}\end{array}$

The surgeon generally endeavors to use the highest power density that can be safely controlled, thereby minimizing the duration of the exposure and unwanted tissue injury by conductive heating of the tissue during contact with the laser beam.

The primary result of the laser tissue interaction produces the classical histology of injury. The center of the wound is the zone of ablation, where tissue is vaporized or removed given a sufficiently high power density. This is followed by a zone of irreversible injury or necrosis, which is followed by a zone of reversible injury. Minimizing the duration of laser exposure will optimize the tissue effects for most applications by reducing conductive thermal injury to the tissues adjacent to the area of exposure to the laser beam.

Laser Use in Minimally Invasive Surgery

Laser utilization offers several advantages during operative laparoscopy.

These devices can provide substantial convenience and time savings for the surgeon by enhancing precision, control, and hemostasis, while decreasing the need for instrument swapping.

Virtually all laser wavelengths have found some utility in laparoscopic procedures.

The KTP: YAG, holmium and Nd: YAG lasers are the most versatile and are the least intrusive on endoscopic visualization.

These versatile devices have many justifiable uses during surgery.

The surgeon should have a thorough understanding of the procedure to be performed as well as the laser device, its delivery systems and safety considerations.

Practice and continued use of these devices will lead to improved outcomes.

We will first discuss laser utilization in laparoscopic and endoscopic surgery. The types of laser technology available for laparoendoscopic use are listed in Table 1. We will describe these laser wavelengths in more detail and consider the applications and shortfalls for each. Specific laser parameters for open surgery are presented in Tables 2, 3, and 4. The reader may find it useful to refer to this information as a rough guide for laparoendoscopic applications as well.

Table 1

Lasers available for laparoscopic use and their properties

Laser	λ	Power max	Absorption chromophore	Tissue necrosis
CO₂	10.6 μ	150 W	Water	200 μ–0.5 mm
Holmium	2.1 μ	150 W	Water	300 μ–2 mm
Argon	488, 514 nm	30 W	Pigment, hemoglobin	300 μ–4 mm
KTP	532 nm	80 W	Pigment, hemoglobin	400 μ–4 mm
Nd:YAG	1.064 μ	120 W	Pigment, proteins	200 μ–2 cm
Dye	508–690 nm	20 W	Pigment	300 μ–1 mm
Diode	905 nm	30 W	Pigment, proteins	500 μ–1 mm

Table 2

Parameters for the CO₂ laser

Tissue type/tasks	Power	Spot diameter
Skin incision	15–25–40 W continuous (CW)	0.2 mm
Subcutaneous tissue/fat incision	60 W CW^c	0.2–0.4 mm
Dissection of breast tissue/creation of flaps	60 W CW^c	0.2–0.4 mm
Muscle incision/transection	60–80 W CW	0.4 mm
Dissection clavipectoral fascia	40 W–60 W^f CW	0.4 mm
Axillary dissection^b	40 W–60 W^f CW	0.4 mm
Laser sterilization^d	40 W CW	10–20 mm
Tissue vaporization/ablation^e	15–100 W CW or pulsed	0.2–20 mm

Wavelength: 10,600 nm; Mode: TEMoo; Handpiece: 125 mm lens^a (0.2 mm spot diameter)

^aThe 125 mm lens is the most convenient for use for most applications. The 50 mm lens with a spot diameter of 0.09 mm achieves the same power density with 25% of the wattage. For example, the 10 W with a 50 mm lens in-focus produces the same power density as 40 W with a 125 mm lens in-focus. However, the 50 mm lens is more cumbersome and difficult to use for non-cutaneous applications

^bThis procedure requires the use of an optical backstop such as the Köcher bronchocele sound, which permits precise dissection without damaging adjacent or underlying structures

^cUsing settings higher than 60 W CW increase the likelihood of causing a flash fire due to ignition of aerosolized fat in the plume

^dLaser sterilization is accomplished by defocusing the laser and gently heating the wound surface. The tissue should be heated just to the point of dessication and slight shrinkage of the wound. Blanching and charring of the wound is indicative of excessive irreversible damage to the wound

^eVaporization or ablation of tissues is most efficient when a high power density is used with a large spot diameter. This permits the surgeon to cover a large area expeditiously

^fUse powers no greater that 40 W until you become proficient and are comfortable with the higher powers. However, 60 W is more efficient and hemostatic

Table 3

Parameters for the KTP laser

Wavelength^a	532 mm
Output	1–40 W^c
Delivery system	Fiberoptic, 0.2 mm, 0.3 mm, 0.4 mm, 0.6 mm diameter fibers. Microstat^® probes are formed to an appropriate configuration for the desired task.
Incision^b	10–20 W continuous wave or pulsed
Coagulation	1–20 W continuous wave or pulsed
Vaporization/ablation^d	10–20 W continuous wave or pulsed

^aThe KTP/YAG system delivers both the 532 nm (KTP) wavelength and the 1,060 nm Nd:YAG wavelength but, at this time, not the two simultaneously. The Nd:YAG can be operated at power settings from 1 to 6 W. It is a more efficient photocoagulator than is the 532 nm wavelength at higher powers

^bThe KTP laser is used with the cleaved fiber in direct contact with the tissue for most uses. Near-contact use is analogous to defocusing the laser beam. Skin incisions are usually not made with the KTP laser because of the extent of lateral tissue damage (burn). However, some users do prefer to make incisions in the anoderm with the laser. Blackened instruments and optical backstops are helpful

^cHigher energies can be used in aqueous environments, but open and laparoscopic procedures generally do not require settings above 20 W CW. Higher powers will result in frequent damage to the fiber’s tip

^dVaporization is best accomplished by using the fiber in a defocused position. Pulsing the laser or using continuous wave mode for brief intervals reduces the likelihood of flaming and burning of the fiber tip. If fiber burnout does occur, the fiber is easily recleaved and the cladding is stripped, making it again ready for use

Table 4

Parameters for use of the Nd:YAG laser

Delivery system	Incision	Coagulation	Vaporization/ablation
Lens^a	NR	20–120 W	20–120 W
Polished fiber^b	NR	20–120 W	20–120 W
Sapphire tip^c	5–25 W	5–25 W	5–25 W
Sculpted/power fiber^d	5–35 W	5–35 W	NR
Cleaved bare fiber^e	10–55 W	20–120 W	20–120 W

Wavelength: 1,060 nm; Output: 1–120 W; Delivery Systems: Fiberoptic, usually with 0.4 mm or 0.6 mm fibers; varies with type of application and terminal delivery system apparatus. Common delivery systems are: lens or polished fiber, sapphire tip, sculpted or “power fiber,” cleaved bare fiber

NR not recommended

^aThe lens system was one of the first applications of the Nd:YAG laser. The laser energy cuts poorly due to extensive forward and back scattering in tissue. The main applications of the lens system was for coagulation or for tissue vaporization

^bPolished fiber applications are mainly for endoscopic coagulation or vaporization techniques. It is poor for making incisions

^cSapphire tips function as a “laser-assisted” device with a large portion (up to 80%) of the laser input being converted to heat and only a small percentage (approximately 20%) being transmitted by the distal third of the tip. This explains the lack of increased response with increasing laser power and also explains why the sapphire tip permits the laser to incise tissues with zones of injury which resemble other lasers and electrocautery (i.e., 300–1,000 μ). Skin incision is not recommended

^dThese recent developments are touted to transmit 81% of laser energy when held in contact with tissue. The fibers which have recently been placed on the market are said to transmit 81% of laser energy when held in contact with tissue. There are no published data which verifies this statement. When we tested one fiber, it did not produce coagulation of pigmented meat when held in water in near contact with the meat. They produce effects that are similar to sapphire tips on tissue but the surgeon can increase incisional speed and effect with increasing power input. Some manufacturers recommend these fibers for skin incision, but many surgeons do not prefer this

^eCleaved fibers (bare fibers) can be used for cutting, coagulation or vaporization. This mode of delivering of YAG energy is extremely dangerous if optical backstops are not used due to the 10° angle of divergence of energy from an optical fiber and due to the extreme forward and backscatter of YAG energy in biological tissues

Laser utilization offers several advantages during operative laparoscopy. These devices can provide substantial convenience and time savings for the surgeon by enhancing precision, control, and hemostasis, while decreasing the need for instrument swapping. Dissection and hemostasis in areas of inflammation and scar can be facilitated and the potential for stray energy damage, which is a known hazard of electrosurgery, can be minimized. Although virtually all laser wavelengths have found some utility in laparoscopic procedures, the KTP: YAG, holmium and YAG laser are the most versatile and are the least intrusive on endoscopic visualization.3–7,9–12,14,16–28,30–33

All of the fiber capable lasers can be used under water or saline irrigation and are effective in cases with edema. These properties provide substantial advantages over monopolar electrosurgical devices. However, the surgeon must understand the laser tissue interaction for the particular wavelength and delivery system chosen in order to minimize the potential for iatrogenic injury.

CO₂ Laser

CO₂ lasers have been used extensively for gynecologic laparoscopic applications but have been rarely utilized for other minimally invasive surgical procedures.

This wavelength is intensely absorbed by cellular water.

The CO₂ laser wavelength is carried via hollow tubes, waveguides and mirrors. Flexible fiberoptics are being developed for clinical use.

The focusing cube and waveguide systems require a direct line of sight or the use of angled mirrors.

CO₂ lasers have been used extensively for an array of gynecologic laparoscopic applications but have been rarely utilized for laparoscopic cholecystectomy and other minimally invasive surgical procedures.6,7,9,10,19 The energy of the CO₂ laser (wavelength = 10,600 nm) is in the far-infrared portion of the electromagnetic spectrum. This wavelength is intensely absorbed by cellular water. This property results in “superficial” injury to tissues and enables the sealing of blood vessels and lymphatics that are up to 0.5–1.0 mm diameter. The potential for inadvertent injury to deeper structures is minimal. The zone of necrosis is approximately 100–300 μ, when the CO₂ laser is used at appropriate fluences in a cutting mode. This most closely resembles the histology of an incision created by the scalpel. This wavelength is absorbed independently of the color of the tissue. Thus, the clinical effect seen in soft tissues is relative to the water content of the target tissue. The local infiltration of tissue with saline or anesthetic solutions will protect or insulate them from injury by the laser beam until the fluid has been vaporized. This laser is the most efficient modality available for ablation or vaporization of large volumes of tissue such as tumor nodules or endometriomas.

The CO₂ laser wavelength is carried via hollow tubes, waveguides and mirrors. Flexible fiberoptics are being developed for clinical use. The Omniguide^® fiber is a flexible chalcogenide glass fiber optic that has been utilized for neuro-surgical and otolaryngological surgeries. The potential exists for broader clinical use, including various general surgical procedures. The laparoscopic use of this wavelength is possible with the use of a focusing cube and an operative laparoscope or with a variety of waveguides designed for multi-puncture laparoscopic applications. The focusing cube permits the use of the CO₂ laser in a free beam mode for cutting, vaporization and coagulation of tissue. The focusing cube also is capable of transmitting an aiming beam. This feature makes it easier for the surgeon to direct the laser energy to the desired target. A variety of procedures such as myomectomy, partial oophorectomy, resection and ablation of endometriomas, adhesiolysis, and even cholecystectomy have been accomplished successfully with this delivery system. Cholecystectomy requires a McKernan-type approach. The successful use of this approach requires knowledge and facility with the operative laparoscope and the surgeon’s ability to visualize the desired target and maneuver a micromanipulator or joy stick. The surgeon can alter the tissue effect by focusing or defocusing the laser beam as well as varying the laser wattage selected.

Laser waveguides are hollow tubes with mirror-like surfaces which reflect the CO₂ wavelength. Waveguides are available in both rigid and flexible versions, and can be used to achieve a spot size (i.e., burn or incision) which is in the range of 0.8–2.2 mm. However, laser waveguides, particularly those capable of carrying high powers are increasingly difficult to obtain today. As a general principle, the waveguide is used in a non contact fashion, particularly since tissue contact can obstruct the waveguide and liquid can be drawn into the waveguide by capillary action. The resultant of these events is the irreversible destruction of the waveguide.

The successful use of this laser for dissection and hemostasis requires that the surgeon be facile and expert with the laser as this will affect the ability to dissect tissues and achieve an adequate degree of hemostasis. Both the focusing cube and waveguide systems require a direct line of sight or the use of angled mirrors. This further complicates the maneuverability of these devices more so than fiber capable lasers and conventional instruments. Both configurations require flowing gas to cool the system and to prevent vaporized tissue plume from being thrown into the device. The most frequently used purge gases are argon and carbon dioxide. High CO₂ gas flow rates can actually absorb the laser energy and reduce its efficiency (i.e., the transmission of energy from the laser to the tissue). Therefore, lower flow rates (i.e., 1 L/min.) are suggested. Some laser systems are equipped with a nitrogen purge gas system. The surgeon should NOT use nitrogen during laparoscopy as its absorption from the peritoneum can cause “the bends.”

The optimal use of the CO₂ laser for laparoscopic or open use is achieved when the beam is oriented perpendicular to the desired target. Hemostasis is enhanced by tissue compression, the use of epinephrine containing local anesthetic solutions and the ability of the operator to recognize the presence of a vessel prior to its division. Under these conditions, the surgeon defocuses the laser (i.e., moves the handpiece, waveguide or operating laparoscope farther away from the target) and then applies short bursts of energy to the vessel in the area to be divided. This maneuver heats and coagulates the vessel, thereby enabling its division by the focused beam. The surgeon should use the highest power setting with which he/she is comfortable as this will enable more efficient cutting, better hemostasis and less thermal injury to the wound edges by minimizing conductive and radiative heat loss into the wound. Intermittent evacuation of the vaporized tissue plume or the use of a re-circulating filtration system assure a clear field of view and prevents absorption of toxic products of combustion by the patient. This problem is identical in magnitude and toxicity to vaporized tissue plume created by any electrosurgical, thermal or laser source. Similarly the “smoke” should not be vented into the operating room as it should be considered hazardous for physician OR personnel. OSHA/NIOSH has written regulations which require that physician OR staff be protected from vaporized tissue plume regardless of its source.1,52,56,57

Argon Laser

The argon laser has been used extensively for gynecologic laparoscopic procedures.

Visible light wavelengths can be passed through water, enabling the argon laser to be used in aqueous environments such as the bladder and in the presence of irrigating fluids as is routinely encountered during abdominal and pelvic procedures.

Both free-beam and conventional fiberoptic applications are utilized during operative laparoscopy.

White or lightly colored tissue will not cut efficiently and will not be vaporized (ablated) unless they are first painted with India ink, indigo carmine dye or another exogenous chromophore.

One of the main drawbacks of the argon laser is the camera/eye safety filter which must block the six wavelengths produced by the laser. These filters are usually a deep orange color and absorb 30–60% of the visible spectrum, resulting in color distortion of the image.

The argon laser has been used extensively for gynecologic laparoscopic procedures.10,11,16–21,26 This laser produces light in the visible portion of the spectrum. This laser actually produces six lines (wavelengths). However, the majority of the laser output is in the blue-green spectrum (wavelengths = 488, 514 nm). This energy is intensely absorbed by hemoglobin and melanin although other exogenous chromophores will absorb these wavelengths efficiently. Visible light wavelengths can be passed through water, enabling the argon laser to be used in aqueous environments such as the bladder, during hysteroscopy, arthroscopy and in the presence of irrigating fluids as is routinely encountered during abdominal and pelvic procedures. This property enables the surgeon to photocoagulate a bleeding area while irrigating to locate the source of the bleeding.

Both free-beam and conventional fiberoptic applications are utilized during operative laparoscopy. A Microslad unit may be coupled with the operative laparoscope. A gimbaled mirror and joy stick allow the surgeon to maneuver the beam in the surgical field. The fiber can be used in both a contact and non-contact mode.

Argon laser light penetrates and scatters in tissues. The resultant damage can be as much as 6 mm depending upon the tissue exposed. When used in an incisional mode, the speed of incision and the degree of hemostasis are adequate. Blood vessels on the order of 2 mm diameter can be divided and coagulated with this wavelength. Although some authors have reported successful hemostasis with vessels as large as 3–4 mm diameter, delayed re-bleeding may occur. Therefore the surgeon would do well to use ligature and Hemo-clip methods for hemostasis in these instances. The etiology of the delayed bleeding is necrosis of photocoagulated tissue and resultant tissue slough. This condition also occurs after use of the Nd: YAG laser in a free beam mode on similar tissues.

The contact or fiber optic method is much more easily mastered than is the free beam approach since the surgeon has direct tactile feedback from the tissue. The speed of incision and the degree of hemostasis are adequate and the more selective absorption of the wavelength in hemoglobin enables the surgeon to photocoagulate vessels prior to their division by bringing the fiber away from the tissue surface. This maneuver is similar to defocusing the free beam. The defocused mode is used to vaporize endometriomas. Some manufacturers produce a variety of sculpted fibers and metal-jacketed fiber delivery systems. These fibers are constructed to be more durable and work “more like a scalpel” due to absorption of some of the laser energy in the fiber resulting in heating of the fiber. This produces an optically driven cautery effect. So-called bare or urologic fibers are easily used and are cleaved and stripped as the fiber end degrades with use. Optimal cutting occurs by using the tip of the fiber either end-on or oblique to the plane of the dissection.

Since these wavelengths are color dependent, the surgeon should note that white or lightly colored tissue such as meniscus and tumor implants will not cut efficiently and will not be vaporized (ablated) unless they are first painted with India ink, indigo carmine dye or another exogenous chromophore. A droplet of blood placed on the surface is sometimes effective for this purpose. Blackened or ebonized instruments and the use of optical backstops are required to prevent beam reflection and iatrogenic injury.

One of the main drawbacks of the laparoscopic use of the argon laser is the camera/eye safety filter. The eye and camera filters must block the six wavelengths produced by the laser. These filters are usually a deep orange color and absorb 30–60% of the visible spectrum. As a result, the color balance of the image is distorted and the need for a high powered light source is critical to the surgeons’ ability to visualize the operative field. Many laser systems have intermittent shutter mechanisms which place the filter in the visual field only while the laser is actually being fired. The surgeon must be an expert at the local anatomy and the details of the procedure prior to attempting to work with this laser. These factors make the use of the argon laser a rarity today.

Nd: YAG Laser

This wavelength is carried via conventional fiberoptics and, like visible light lasers; the energy will be transmitted through water.

The energy can be applied to tissues with a wide array of delivery systems including: cleaved bare fibers, GI fibers, sapphire tips, sculpted fibers, as well as free beam via a micromanipulator or Microslad^® unit.

The energy of the Nd: YAG laser is intensely absorbed by tissue protein and chromophores and is highly scattered in tissue. These properties result in deep penetration of the energy and much greater damage below the tissue than can be appreciated at the surface.

Use of the bare fiber for dissection has been practiced safely by surgeons having a detailed understanding of anatomy and by orienting the fiber in a plane which is tangential to the line of incision to limit the forward scattering of the energy into the tissues.

The YAG wavelength is a poor ablating wavelength, particularly when compared to the CO₂, KTP or holmium wavelengths whose rates of ablation are significantly faster.

The neodymium YAG laser produces near infrared light at a wavelength of 1,060 nm. This wavelength is carried via conventional fiberoptics and, like visible light lasers; the energy will be transmitted through water. The energy can be applied to tissues with a wide array of delivery systems including: cleaved bare fibers (i.e., urologic fibers), polished GI fibers, sapphire tips (i.e., the delivery device which is marketed as the Contact Laser^®), sculpted fiber (e.g., Microcontact^® tip and various other proprietary versions of this technology), as well as free beam via a micromanipulator or Microslad^® unit.3,5,6,10–12,16–21,26–28 The energy of the Nd: YAG laser is intensely absorbed by tissue protein and chromophores, and is highly scattered in tissue. These properties result in deep penetration of the energy and much greater damage below the tissue than can be appreciated at the surface. This makes non contact (i.e., GI fiber, free beam) and bare fiber applications of the Nd: YAG laser extremely dangerous unless the surgeon has a thorough understanding of the laser-tissue interaction and orients the beam in a direction which would reduce the likelihood of damaging nearby structures. The Nd: YAG laser is a poor cutting instrument when it is used in a non contact mode. The development of sapphire tips and sculpted fiber technologies facilitated use of this laser in contact with tissue. Free-beam type applications can result in damage to as much as 1–2 cm of liver tissue and the photocoagulation of vessels up to 4 mm in diameter.

Sapphire tip technology creates a combined thermal and optical interaction with tissue. Much of the Nd: YAG energy is absorbed by the sapphire or fiber tip and converted to heat. The result is to produce optically driven cautery.16–20 The temperature of the tip can be tightly regulated for some applications. These instruments improve the cutting ability of the laser, but the tissue damage and the extent of coagulation are reduced dramatically. The histology of these devices is quite similar to the results produced by electrosurgical devices. Since their main tissue interaction is thermal cautery, the rate of incision and the degree of hemostasis can be reduced when these devices are used in the presence of irrigating fluids or in the aqueous environment of the bladder or joint space. The surgeon adjusts the laser parameters accordingly in order to achieve the desired effect. Sapphire tips are fragile and are expensive in comparison to other delivery systems. They remain hot for a short while after the laser has been turned off, which can cause damage or adherence to adjacent structures upon accidental contact. The sapphire tip may become disconnected from the fiber while operating and may be lost. When these devices are used in vascular and aqueous conditions such as the bladder, prostate or uterus, the fibers must NEVER be cooled with air or gas as embolism of gas has proven fatal. Fiber cooling with saline or other irrigating fluids is quite safe however. Sapphire tip technology is seldom used today due to these issues with their use and since other, less expensive alternatives are available.

Only gold members can continue reading. Log In or Register to continue