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Principles of Laparoscopic Hemostasis: Ligation Techniques
REFEREED
CLINICAL TECHNIQUES Introduction to Clinical Techniques Section
Beginning this month and for the next several issues, the Clinical Techniques section of JEVS will present a series of articles on Equine Laparoscopy. I want to thank Dr. Dean Hendrickson for organizing this excellent series of articles for your reading and surgical advancement. Dr. Hendrickson picked the authors and topics based on his many years of experience and expertise using this state-of-the-art surgical technique. On completion of this series, the reader should have a good understanding of the instrumentation and basic techniques that have been developed to date. The first two articles cover the training for laparoscopic surgery, which is key in becoming proficient and comfortable with the surgery, followed by the use of coagulation in laparoscopic surgery. The article on coagulation, in particular, is important in preventing intraoperative and postoperative complications so pay special attention to the potential pitfalls and advantages of the several methods described. Please let Ed Squires and me know if there is something more needed on this subject to help you become proficient. Remember—practice, practice, and more practice before taking this advanced surgical technique to the operating suite! Dr. James Orsini Associate Editor
Principles of Laparoscopic Hemostasis: Ligation Techniques Donna L. Shettko, DVM, ACVS,a and Dean A. Hendrickson, DVM, MS, ACVSb Visualization of the laparoscopic field is essential for successful surgery. Laparoscopic surgery should be virtually bloodless and ideally it is preferrable to prevent hemorrhage in the first place. This situation can only be accomplished if field hemostasis is maintained throughout the procedure. Limitations of laparoscopic surgery such as the type of access and a small visual field make a second attempt at hemostasis extremely difficult and puts the patient at risk if bleeding does occur.1 Uncontrolled hemorrhage may force the procedure to be converted to an open technique if possible. In some instances the operative site may be difficult to approach through an open technique, resulting in the absolute need to obtain hemostasis via the laparoscope. In addition to blood obscuring the visual field, it has the ability to absorb much of the illuminating light. Despite increasing the intensity of the light source, the surgical field remains dark; limiting one’s ability to obtain hemostasis.2
From the Western University of Health Sciences, College of Veterinary Medicine, Pomona, CAa; and Colorado State University, Veterinary Teaching Hospital, Department of Clinical Sciences, Fort Collins, CO.b Reprint requests: Donna L. Shettko, DVM, ACVS, Western University of Health Sciences, College of Veterinary Medicine, 309 E Second St, Pomona, CA 91766. 0737-0806/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2007.12.003
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Tissue handling is as important in laparoscopic surgery as in open surgery. How hard can you retract the tissue before it tears? Will there be significant bleeding if tearing occurs? How hard can you push a solid organ for retraction before there is parenchymal bleeding or a capsular tear? Do you have enough of the vessel exposed before clipping it so that in the event the clip comes off you can still find the vessel edge and grasp it again to work with it? Do you have enough exposure to control bleeding should it occur before your next operative move? All of these are fundamental questions the laparoscopic surgeon must address and reassess as the surgical case proceeds. The ability to plan a surgical procedure, understand the important anatomic relationships and variations, and to anticipate and work with the unexpected all bear on a successful outcome of the procedure. The surgeon must understand the different techniques and limitations used to obtain hemostasis in laparoscopic surgery. Ideally, hemostatic techniques and coagulation methods should be safe and reliable and should cause minimal collateral damage to surrounding tissues.3 This article describes some of the more commonly used methods of hemostasis and coagulation.
COAGULATION Surgeons have historically relied on energy sources to achieve hemostasis during surgery in addition to mechanical
Journal of Equine Veterinary Science Vol 28, No 1 (2008)
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means such as sutures and clips.2 The rapid growth of laparoscopic surgery has led to the development and adaptation of these energy sources for use in the laparoscopic environment.4 The premise behind the use of energy for coagulation is the conversion of energy to heat, which is then directly applied to the tissue. The various ways in which the heat is delivered to tissue are what allows the surgeon to perform dissection, cutting, or coagulation in a controlled and predictable fashion.4 There are many potential perils with energy that are unique to laparoscopic surgery. Given that electric currents have specific effects on tissue, the temperature attained in the tissues may predict the tissue changes observed.2 1. At 458C, collagen uncoils and may reanneal, allowing apposed edges to form covalent bonds and fuse.2 2. At 608C, irreversible protein denaturation occurs and coagulation necrosis begins. This is characterized by a blanching in color.2 3. At 808C, carbonization begins and leads to drying and shrinkage of tissue.2 4. At 90–1008C, cellular vaporization occurs and vacuoles form and coalesce, leading to complete cellular destruction. The surgeon observes a plume of gas and smoke that represents water vapor.2 5. Temperatures of 1258C or greater result in complete oxidation of protein and lipids, leading to carbon residue or eschar formation.2 Reviewing the definitions pertaining to laparoscopic coagulation further enhances the surgeon’s overall understanding of energy and its effect on tissue. Electrosurgery is the application of alternating electric current that passes through the patient’s tissues to complete the circuit.1 Electrosurgical coagulation is when the electrode is applied directly to the tissue, causing less concentration of the current.1 The cells are desiccated by the vaporization of intracellular water, which leads to the formation of a coagulum.1 Coagulation is achieved, but the lateral thermal damage is increased.1 Electrosurgical fulguration occurs when the electrode does not touch the target organ but the electric current sparks across the gap, thus charring and coagulating the superficial surface over a wide area.1 One of the main energy sources currently used in laparoscopic surgery is electrosurgery.4 Because many of the instruments used for electrosurgery are modifications of those used in open surgery, most surgeons are somewhat familiar with principles of electrosurgery. An introduction to energy sources aids in the understanding of how energy accomplishes hemostasis, ultimately improving the surgeon’s ability to perform electrosurgery in an appropriate and efficacious manner.5 Electricity, laser energy, and ultrasonic waves have been the energy sources most commonly used. These three
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modalities all function by the same basic principles. The basic understanding of the function of each energy source is essential. Anticipating potential complications permits the surgeon to make thoughtful decisions regarding operative settings and to avoid potential problems.4 Electrosurgery is widely used for laparoscopic hemostasis because of familiarity, cost, and versatility. The active electrode is a conductor connected directly to the electrosurgical unit generator.2 The return electrode is a conductor that accepts current from the active electrode and returns it to the electrosurgical unit, completing the electric circuit.2 The configuration of the active and return electrode determines the path of current or mode during electrosurgery.2 In general, at a fixed energy setting, the size of the active electrode in contact with the tissue determines the rate of heating.4 The smaller the contact area, the faster the heating. There are two common methods of delivering energy for coagulation: monopolar and bipolar electrodes. Currently monopolar current is the most widely used in laparoscopic surgery. Monopolar electrode surgical units are relatively inexpensive and easy to modulate to achieve the desired tissue effect, coagulation. It has established itself as an effective and safe modality in laparoscopic surgery. The desired effect of using monopolar electrosurgery is to coagulate, yet cause a minimal amount of thermal injury.6 In particular, knowledge of the principles and risks of monopolar electrosurgery helps prevent those iatrogenic injuries. The monopolar electrode current passes from the active electrode through the wound and returns to passive return electrode (grounding pad).1 The current that is concentrated at the tip of the electrosurgical instrument dissipates through the patient’s body, and is conducted back to the electrosurgical unit by the grounding pad where the large area of contact dissipates the current density.1,7 The advantage of bipolar electrosurgery is that many problems with misdirection of the current are avoided. The output of the electrosurgical generator must be decreased because the two terminals are of equal size and are located across from each other. The current is only conducted by the tissue between the distal electrodes. This lower energy requirement produces less lateral tissue damage and necrosis.8 The tissue to be coagulated is held between the jaws of the instrument and the current is then applied.1 The current heats the tissue slowly and safely.1 The challenges of laparoscopic surgery occur partly because of the decreased visual field. Accidental injury is increased, and early identification of the injury may be delayed and more difficult to identify. The initial attempts to use electrosurgery in the laparoscopic setting were associated with specific complications. In monopolar electrosurgery, the electrical current takes the path of least
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resistance to return to the return electrode.9 The main problem is secondary to stray current, which may cause visceral injury. This stray current may occur in three ways: insulation failure, direct coupling, and capacitance coupling.9 The first hazard is insulation failure. Laparoscopic instruments and electrosurgical electrodes are insulated to prevent electrical current from contacting surrounding structures.2 A break in the insulation that may be too small to be seen can allow electrical current to leak or arc to a metal trocar or to an adjacent viscus, causing thermal injury.2 Experimentally, it has been shown that defects of insulation that are not noticed can deliver nearly 100% of available electrical energy to sites outside the laparoscopic field of view.10 The path the current may take and the density are unpredictable in this situation. The injury to the tissue may be out of the visual field of the surgeon and therefore not be identified.2 The cause of this can be minimized by routine inspection of all electrodes at the start of each case, especially the portion that contacts the flapper valve of the trocar.4 This is the first point of failure attributable to repeated mechanical trauma. Given that most insulation failures are so difficult to identify, current leakage detectors can be used to test adequacy of insulation.2 Safety recommendations to minimize insulation failure are used to test all instruments for current leakage, especially if single-use instruments are being recycled.1 Insulation failure does occur more commonly with the repeated use of single-use instruments.11 Another complication is direct coupling. This occurs when the current traveling from one conductive material touches or arcs to another.2 This method of coagulation is often used by surgeons when the tissue is grasped in one instrument and then is touched by a different active electrode.2 This can occur when the active electrode comes into contact with other (noninsulated) metal instruments, cannulas, or the laparoscope. This technique has the potential liability of the current being directed to the nontarget tissue.1,4 This also can occur outside of the visual field when the secondary electrode comes in contact with a viscus. The occurrence of direct coupling can be minimized by making sure all the conductive instruments are in the surgeon’s direct field of view and not in contact with any nontarget tissue before activation of the electrosurgical unit.2 The third complication of monopolar electro surgery is capacitive coupling. Capacitive coupling is a phenomenon that explains many of the injuries that have been reported with the use of monopolar electrosurgery.2 Capacitive coupling occurs when a conductor has intact insulation but passes through a nonisolated conductor such as a metal trocar, operative laparoscope, or metal suction irrigation tip. Capacitive coupling also can occur when crossing the active electrode with another laparoscopic instrument.4
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The electromagnetic forces produce a coupled current to the outside conductor, resulting in the transfer of energy to unintended structures outside the field of view.2 If the metal canula is in direct contact with the body wall, energy is dissipated to the body wall and sent to the return electrode over a large enough area to avoid burns.1 Tissue injury may occur during situations secondary to capacitive coupling when high voltages are produced when the active electrode does not have tissue contact or when the power setting is increased. The capacitance coupled current may follow unpredictable pathways back to the return electrode, including severe tissue damage in nearby bowel or other viscera.1 If the trocar is all metal, this energy returns to the ground plate through the abdominal wall. A dangerous situation can arise when a metal trocar is used with a plastic screw anchor at the skin level. This electrically isolates the trocar from draining its capacitance coupled charge into the abdominal wall, causing a thermal injury if bowel is contacted.4 One way to limit these types of injuries is to use all-metal trocar systems without a plastic screw anchor to pass the laparoscope.2,4 This is the optimal situation from a safety standpoint. Complications that occur infrequently should be recognized. These are spark or arc injuries. They occur most frequently when higher-voltage coagulation waveforms are used and when the electrosurgical instrument is activated while not in contact with tissue.1 Lastly, when current is allowed to pass through an unintentionally narrowed return circuit, the local current density may increase, resulting in excess heat and leading to a thermal tissue burn.4
ENDOSCOPIC CLIPS A clip applier is a device used to apply clips to permanently close small structures such as blood vessels. They are available as both single-use (disposable) and multi-use (reusable) instruments.2 The advantage of using the reusable clip applier is that the cost of the surgery is decreased. Small, medium-large, and large clip sizes are available. The more commonly used sizes of clips are for ligation of small (2 5 mm) structures. The endo-clips are available as both single and multiple clip appliers.1 The techniques for ligating vessels with the clip appliers are the same for both reusable and disposable equipment. Clips are applied to the major vessels in a manner similar to the techniques used in open surgery. When using the clips, the vessels need to be ligated before they are transected.1 The tissue planes are dissected and individual vessels are isolated to decrease the chances of hemorrhage.1 The technique to use the clip applier is to place the jaws of the clip applier around the tissue to be ligated and when activated compress the clip into its closed position.2 Important features of the clip design are the serrations on the concave surface of the clip to reduce the likelihood of
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the clip slipping off the vessel.2 Application of the clips requires visualization of both sides of the clip to ensure that adequate tissue is penetrated and to prevent inadvertent clipping of nontarget tissues.2 Absorbable clips are also available. These clips are usually made of polyglycolic acid polymers.2 These clips have identical ligation properties but can cause adhesion formation.2 Ischemic necrosis can occur when the metallic clips are placed very close to the bowel wall, resulting in stricture or perforation.2 Complications can hopefully be prevented by adequate visualization of the vessels and structures before application of the clip. Instead of using the clips, another type of ligature such as the loop ligature may be more appropriate.
LINEAR STAPLING DEVICES Linear stapling devices are primarily used for performing anastomosis but they can be important when used to prevent major hemorrhagic complications.2 For large vessels or thick broad tissue planes, the tissue planes can be readily resected; a disposable endoscopic stapler is an excellent means of achieving hemostasis and tissue apposition.1
ENDO LIGATURES The pre-tied suture loops with slip knots have a limited use in primary hemostasis because the vessel or vascular pedicle must first be divided, grasped, and then secured.2 Using the pre-tied loop would leave a bleeding vessel while placing the loop.2 The pre-tied loops are ideally suited for well-isolated pedicles such as a cryptorchid testicle. There is a manufactured, pre-tied suture loop called the Endoloop. The Endoloop is a preformed knotted loop with a sliding knot at the end of a disposable nylon cannula that is designed to fit over vascular pedicles and then tightened.1 Endoloop ligatures are available in chromic gut, polydioxanone (PDS II) suture, coated Vicryl (polyglactin 910) suture, Monocryl (poliglecaprone 25) suture, and Ethibond Excel polyester suture.1 When using the Endoloop, the introducer sleeve is placed through a trocar into the abdomen. The loop is then advanced into the field of view and placed in proximity to the pedicle to be ligated.1 The vessel or pedicle that is to be ligated is then isolated by dividing and separating surrounding peritoneum and connective tissue.5 The suture can then be placed around the pedicle with a grasping forceps stabilizing the tissue.5 The jaws of a grasping forceps are passed through the loop to hold the pedicle and draw the tissue into the loop of the ligature.1,5 Once the loop is in position, the plastic knot pusher is broken at its scored end outside the body.1 The short end of the pusher is pulled while the long section is advanced through the trocar to close the loop tightly around the pedicle.1 Most normal-sized ovaries and testicles fit
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within the loop of the Endoloop.1 One of the disadvantages is the short length of the knot pusher, making it difficult to use in standing surgery through the paralumbar fossa.1 There are two types of laparoscopic ligatures: intracorporeal and extracorporeal. The intracorporeal and extracorporeal pre-tied laparoscopic knots are very useful for vessel ligation. Because tying of intracorporeal knots is difficult, pre-tied knots for encircling ligatures have been developed.11 An excellent technique for laparoscopic extracorporeal tying was developed in 1971 by Dr. H. Courtenay Clarke, using a knot pusher to secure the knot in a manner very similar to the way one would hand-tie sutures at laparotomy.5 It is much easier to tie laparoscopic knots outside of the body, where the surgeon can see the knot tying (extracorporeal). The extracorporeal ligatures are placed through a 5-mm diameter plastic sheath, which helps to introduce the ligature into the body cavity and acts as a knot pusher.5,11 These knots are one of the fundamental knots of laparoscopy and are used primarily for ligation of pedicles and tissue approximation.1 When the ligatures are passed around a clearly dissected vessel, careful attention must be adhered to so as not to saw the tissue or vessel as the ligature is being passed.2 The extracorporeal surgeon’s knot is the easiest to tie because the knot is tied outside the body in exactly the same way that it is tied in open surgery.1 Another extracorporeal slip knot is the Roeder knot. It is one of the most useful slipknots used in laparoscopic surgery. The advantage of the Roeder knot is that it is rapidly tied and is easier to advance to the specific site on the tissue than the extracorporeal surgeon’s knot.1 The suture material itself makes a difference when tying the Roeder knot. Using polydioxanone or other monofilament suture is not recommended for tying the Roeder knot. The specific properties of the monofilament suture material may cause the knot to slip.1 If monofilament suture is used, the Roeder should not be used and the modified Roeder knot should be used. The modified Roeder allows for increased friction and decrease knot slippage.1 Because of the additional friction created by the modified Roeder knot, the choice of suture material should be taken into consideration. Natural catgut and Vicryl suture are two of the suture materials that should not be used.12 Extracorporeal knots have distinct advantages over intracorporeal laparoscopic slip knots when only single ligatures need to be applied.1 Intracorporeal suturing techniques create knots entirely within the body cavity and enable the surgeon to ligate and perform a simple interrupted or continuous suture pattern.1 The intracorporeal square knot is tied the same way as the traditional square knot. The difference is that the two instruments are used to handle the suture within the abdomen.1 Needle holders and graspers with locking mechanisms greatly facilitate the
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process of intracorporeal suturing and knot tying.1 Intracorporeal suturing is very difficult to master and is a challenging skill to learn. The surgeon should practice before using the intracorporeal knot in the surgical setting. When it is necessary to use a needle or to pass a ligature around a vessel that is not free from surrounding tissue, the Endoknot product may be used.1 The Endoknot is a suture attached to a straight needle at one end and a disposable nylon cannula at the other. The needle and cannula are introduced and the needle is passed around or through the structure to be sutured.1 The needle is brought out of the trocar and an extracorporeal Roeder knot is tied and advanced to the tissue site, using the nylon cannula.1 It is the surgeon’s preference as to which suture material use. Yet many features are important when choosing the type of suture. How well the suture handles, friction, and knot security are all important characteristics to consider when choosing the suture material. Some prefer polydioxanone because of its memory or rigidity, which keeps the loop open and the knot sliding easily. Size 1 Maxon in a 4-S modified Roeder knot provides knot security superior to that of commercially available knots.13
REFERENCES 1. Newman RM, Traverso LW. Principles of laparoscopic hemostasis. In: Scott-Conner CE, ed. The sage’s manual fundamentals of laparoscopy and GI endoscopy. New York: Springer; 1999:57–68. 2. Fischer AT Jr. Equine diagnostic surgical laparoscopy. Philadelphia: W.B. Saunders; 2002. 3. Lantis JC, Durville FM, Connolly R, Schwaitzbury SD. Comparison of coagulation modalities in surgery. J Lap Adv Surg 1998;8:381–394. 4. Laycock WS, Hunter JG. Electrosurgery and laser application. In: MacFadyen BV Jr, ed. Operative laparoscopy and thoracoscopy. Philadelphia: Lippincott- Raven; 1996:79–91. 5. Burke RK. Electrosurgery: clinical and comparative concepts. In: Cohen SM, ed. Operative laparoscopy and hysteroscopy. New York: Churchill Livingstone; 1996:37–51, 119 120. 6. Brunicardi CR. Minimally invasive surgery. In: Brunicardi FC, ed. Schwartz’s principles of surgery. New York: McGraw Hill; 2005:389–392. 7. Airan MC, Sung-Tao Ko. Electrosurgery techniques of cutting and coagulation. In: Arregui ME, ed. Principles of laparoscopic surgery, basic and advanced techniques. New York: Springer Verlag; 1995:30–33. 8. Tucker RD, Platz CE, Sievert CE, Vennes JA, Silvis SE. In vivo evaluation of monopolar versus bipolar electrosurgical polypectomy snares. Am J Gastroenterol 1990;10:1386–1390.
SUMMARY The best plan is a surgical procedure that is well thought out ahead of time. Organization and prioritization of the surgical steps from beginning to end are essential. Once the procedure has started, adequate visualization and identification of all structures before dissection saves time and produces a better outcome. Rapid or mishandled tissue often results in nuisance bleeding that may obscure the operative field and lead to an error. Electrosurgical instruments should be safely applied to the vessel to be ligated before its dissection, helping to prevent uncontrolled hemorrhage. When active bleeding occurs, having thought out the steps needed to remedy the situation is essential. Surgeons should be no different from the pilot who regularly reviews contingency plans for an emergency situation.
9. Bhoyrul S, Mori T, Way LW. Principles of instrumentation. In: Way LW, ed. Fundamentals of laparoscopic surgery. New York: Churchill-Livingstone; 1995. 10. Centers for Disease Control and Prevention. Deaths following female sterilization with unipolar electrocoagulating devices. Morbid Mort Weekly Rep 1981;30:149. 11. Thompson SE, Potter L. Electrosurgery, lasers and ultrasonic energy. In: Freeman LF, ed. Veterinary endosurgery. St Louis: Mosby; 1999. 12. Hendrickson DA. History and instrumentation of laparoscopic surgery. Vet Clin North Am, Equine Pract 2000;16:233–249. 13. Stoloff DR. Laparoscopic suturing and knot tying techniques. In: Freeman LJ, ed. Veterinary endosurgery. St Louis: Mosby; 1998. 14. Shettko DL, Frisbie DD, Hendrickson DA. A comparison of knot security of commonly used hand tied laparoscopic slipknots. Vet Surg 2004;33:521–524.
CLINICAL TECHNIQUES Introduction to Clinical Techniques Section
Beginning this month and for the next several issues, the Clinical Techniques section of JEVS will present a series of articles on Equine Laparoscopy. I want to thank Dr. Dean Hendrickson for organizing this excellent series of articles for your reading and surgical advancement. Dr. Hendrickson picked the authors and topics based on his many years of experience and expertise using this state-of-the-art surgical technique. On completion of this series, the reader should have a good understanding of the instrumentation and basic techniques that have been developed to date. The first two articles cover the training for laparoscopic surgery, which is key in becoming proficient and comfortable with the surgery, followed by the use of coagulation in laparoscopic surgery. The article on coagulation, in particular, is important in preventing intraoperative and postoperative complications so pay special attention to the potential pitfalls and advantages of the several methods described. Please let Ed Squires and me know if there is something more needed on this subject to help you become proficient. Remember—practice, practice, and more practice before taking this advanced surgical technique to the operating suite! Dr. James Orsini Associate Editor
Principles of Laparoscopic Hemostasis: Ligation Techniques Donna L. Shettko, DVM, ACVS,a and Dean A. Hendrickson, DVM, MS, ACVSb Visualization of the laparoscopic field is essential for successful surgery. Laparoscopic surgery should be virtually bloodless and ideally it is preferrable to prevent hemorrhage in the first place. This situation can only be accomplished if field hemostasis is maintained throughout the procedure. Limitations of laparoscopic surgery such as the type of access and a small visual field make a second attempt at hemostasis extremely difficult and puts the patient at risk if bleeding does occur.1 Uncontrolled hemorrhage may force the procedure to be converted to an open technique if possible. In some instances the operative site may be difficult to approach through an open technique, resulting in the absolute need to obtain hemostasis via the laparoscope. In addition to blood obscuring the visual field, it has the ability to absorb much of the illuminating light. Despite increasing the intensity of the light source, the surgical field remains dark; limiting one’s ability to obtain hemostasis.2
From the Western University of Health Sciences, College of Veterinary Medicine, Pomona, CAa; and Colorado State University, Veterinary Teaching Hospital, Department of Clinical Sciences, Fort Collins, CO.b Reprint requests: Donna L. Shettko, DVM, ACVS, Western University of Health Sciences, College of Veterinary Medicine, 309 E Second St, Pomona, CA 91766. 0737-0806/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2007.12.003
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Tissue handling is as important in laparoscopic surgery as in open surgery. How hard can you retract the tissue before it tears? Will there be significant bleeding if tearing occurs? How hard can you push a solid organ for retraction before there is parenchymal bleeding or a capsular tear? Do you have enough of the vessel exposed before clipping it so that in the event the clip comes off you can still find the vessel edge and grasp it again to work with it? Do you have enough exposure to control bleeding should it occur before your next operative move? All of these are fundamental questions the laparoscopic surgeon must address and reassess as the surgical case proceeds. The ability to plan a surgical procedure, understand the important anatomic relationships and variations, and to anticipate and work with the unexpected all bear on a successful outcome of the procedure. The surgeon must understand the different techniques and limitations used to obtain hemostasis in laparoscopic surgery. Ideally, hemostatic techniques and coagulation methods should be safe and reliable and should cause minimal collateral damage to surrounding tissues.3 This article describes some of the more commonly used methods of hemostasis and coagulation.
COAGULATION Surgeons have historically relied on energy sources to achieve hemostasis during surgery in addition to mechanical
Journal of Equine Veterinary Science Vol 28, No 1 (2008)
DL Shettko et al Vol 28, No 1 (2008)
means such as sutures and clips.2 The rapid growth of laparoscopic surgery has led to the development and adaptation of these energy sources for use in the laparoscopic environment.4 The premise behind the use of energy for coagulation is the conversion of energy to heat, which is then directly applied to the tissue. The various ways in which the heat is delivered to tissue are what allows the surgeon to perform dissection, cutting, or coagulation in a controlled and predictable fashion.4 There are many potential perils with energy that are unique to laparoscopic surgery. Given that electric currents have specific effects on tissue, the temperature attained in the tissues may predict the tissue changes observed.2 1. At 458C, collagen uncoils and may reanneal, allowing apposed edges to form covalent bonds and fuse.2 2. At 608C, irreversible protein denaturation occurs and coagulation necrosis begins. This is characterized by a blanching in color.2 3. At 808C, carbonization begins and leads to drying and shrinkage of tissue.2 4. At 90–1008C, cellular vaporization occurs and vacuoles form and coalesce, leading to complete cellular destruction. The surgeon observes a plume of gas and smoke that represents water vapor.2 5. Temperatures of 1258C or greater result in complete oxidation of protein and lipids, leading to carbon residue or eschar formation.2 Reviewing the definitions pertaining to laparoscopic coagulation further enhances the surgeon’s overall understanding of energy and its effect on tissue. Electrosurgery is the application of alternating electric current that passes through the patient’s tissues to complete the circuit.1 Electrosurgical coagulation is when the electrode is applied directly to the tissue, causing less concentration of the current.1 The cells are desiccated by the vaporization of intracellular water, which leads to the formation of a coagulum.1 Coagulation is achieved, but the lateral thermal damage is increased.1 Electrosurgical fulguration occurs when the electrode does not touch the target organ but the electric current sparks across the gap, thus charring and coagulating the superficial surface over a wide area.1 One of the main energy sources currently used in laparoscopic surgery is electrosurgery.4 Because many of the instruments used for electrosurgery are modifications of those used in open surgery, most surgeons are somewhat familiar with principles of electrosurgery. An introduction to energy sources aids in the understanding of how energy accomplishes hemostasis, ultimately improving the surgeon’s ability to perform electrosurgery in an appropriate and efficacious manner.5 Electricity, laser energy, and ultrasonic waves have been the energy sources most commonly used. These three
47
modalities all function by the same basic principles. The basic understanding of the function of each energy source is essential. Anticipating potential complications permits the surgeon to make thoughtful decisions regarding operative settings and to avoid potential problems.4 Electrosurgery is widely used for laparoscopic hemostasis because of familiarity, cost, and versatility. The active electrode is a conductor connected directly to the electrosurgical unit generator.2 The return electrode is a conductor that accepts current from the active electrode and returns it to the electrosurgical unit, completing the electric circuit.2 The configuration of the active and return electrode determines the path of current or mode during electrosurgery.2 In general, at a fixed energy setting, the size of the active electrode in contact with the tissue determines the rate of heating.4 The smaller the contact area, the faster the heating. There are two common methods of delivering energy for coagulation: monopolar and bipolar electrodes. Currently monopolar current is the most widely used in laparoscopic surgery. Monopolar electrode surgical units are relatively inexpensive and easy to modulate to achieve the desired tissue effect, coagulation. It has established itself as an effective and safe modality in laparoscopic surgery. The desired effect of using monopolar electrosurgery is to coagulate, yet cause a minimal amount of thermal injury.6 In particular, knowledge of the principles and risks of monopolar electrosurgery helps prevent those iatrogenic injuries. The monopolar electrode current passes from the active electrode through the wound and returns to passive return electrode (grounding pad).1 The current that is concentrated at the tip of the electrosurgical instrument dissipates through the patient’s body, and is conducted back to the electrosurgical unit by the grounding pad where the large area of contact dissipates the current density.1,7 The advantage of bipolar electrosurgery is that many problems with misdirection of the current are avoided. The output of the electrosurgical generator must be decreased because the two terminals are of equal size and are located across from each other. The current is only conducted by the tissue between the distal electrodes. This lower energy requirement produces less lateral tissue damage and necrosis.8 The tissue to be coagulated is held between the jaws of the instrument and the current is then applied.1 The current heats the tissue slowly and safely.1 The challenges of laparoscopic surgery occur partly because of the decreased visual field. Accidental injury is increased, and early identification of the injury may be delayed and more difficult to identify. The initial attempts to use electrosurgery in the laparoscopic setting were associated with specific complications. In monopolar electrosurgery, the electrical current takes the path of least
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resistance to return to the return electrode.9 The main problem is secondary to stray current, which may cause visceral injury. This stray current may occur in three ways: insulation failure, direct coupling, and capacitance coupling.9 The first hazard is insulation failure. Laparoscopic instruments and electrosurgical electrodes are insulated to prevent electrical current from contacting surrounding structures.2 A break in the insulation that may be too small to be seen can allow electrical current to leak or arc to a metal trocar or to an adjacent viscus, causing thermal injury.2 Experimentally, it has been shown that defects of insulation that are not noticed can deliver nearly 100% of available electrical energy to sites outside the laparoscopic field of view.10 The path the current may take and the density are unpredictable in this situation. The injury to the tissue may be out of the visual field of the surgeon and therefore not be identified.2 The cause of this can be minimized by routine inspection of all electrodes at the start of each case, especially the portion that contacts the flapper valve of the trocar.4 This is the first point of failure attributable to repeated mechanical trauma. Given that most insulation failures are so difficult to identify, current leakage detectors can be used to test adequacy of insulation.2 Safety recommendations to minimize insulation failure are used to test all instruments for current leakage, especially if single-use instruments are being recycled.1 Insulation failure does occur more commonly with the repeated use of single-use instruments.11 Another complication is direct coupling. This occurs when the current traveling from one conductive material touches or arcs to another.2 This method of coagulation is often used by surgeons when the tissue is grasped in one instrument and then is touched by a different active electrode.2 This can occur when the active electrode comes into contact with other (noninsulated) metal instruments, cannulas, or the laparoscope. This technique has the potential liability of the current being directed to the nontarget tissue.1,4 This also can occur outside of the visual field when the secondary electrode comes in contact with a viscus. The occurrence of direct coupling can be minimized by making sure all the conductive instruments are in the surgeon’s direct field of view and not in contact with any nontarget tissue before activation of the electrosurgical unit.2 The third complication of monopolar electro surgery is capacitive coupling. Capacitive coupling is a phenomenon that explains many of the injuries that have been reported with the use of monopolar electrosurgery.2 Capacitive coupling occurs when a conductor has intact insulation but passes through a nonisolated conductor such as a metal trocar, operative laparoscope, or metal suction irrigation tip. Capacitive coupling also can occur when crossing the active electrode with another laparoscopic instrument.4
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The electromagnetic forces produce a coupled current to the outside conductor, resulting in the transfer of energy to unintended structures outside the field of view.2 If the metal canula is in direct contact with the body wall, energy is dissipated to the body wall and sent to the return electrode over a large enough area to avoid burns.1 Tissue injury may occur during situations secondary to capacitive coupling when high voltages are produced when the active electrode does not have tissue contact or when the power setting is increased. The capacitance coupled current may follow unpredictable pathways back to the return electrode, including severe tissue damage in nearby bowel or other viscera.1 If the trocar is all metal, this energy returns to the ground plate through the abdominal wall. A dangerous situation can arise when a metal trocar is used with a plastic screw anchor at the skin level. This electrically isolates the trocar from draining its capacitance coupled charge into the abdominal wall, causing a thermal injury if bowel is contacted.4 One way to limit these types of injuries is to use all-metal trocar systems without a plastic screw anchor to pass the laparoscope.2,4 This is the optimal situation from a safety standpoint. Complications that occur infrequently should be recognized. These are spark or arc injuries. They occur most frequently when higher-voltage coagulation waveforms are used and when the electrosurgical instrument is activated while not in contact with tissue.1 Lastly, when current is allowed to pass through an unintentionally narrowed return circuit, the local current density may increase, resulting in excess heat and leading to a thermal tissue burn.4
ENDOSCOPIC CLIPS A clip applier is a device used to apply clips to permanently close small structures such as blood vessels. They are available as both single-use (disposable) and multi-use (reusable) instruments.2 The advantage of using the reusable clip applier is that the cost of the surgery is decreased. Small, medium-large, and large clip sizes are available. The more commonly used sizes of clips are for ligation of small (2 5 mm) structures. The endo-clips are available as both single and multiple clip appliers.1 The techniques for ligating vessels with the clip appliers are the same for both reusable and disposable equipment. Clips are applied to the major vessels in a manner similar to the techniques used in open surgery. When using the clips, the vessels need to be ligated before they are transected.1 The tissue planes are dissected and individual vessels are isolated to decrease the chances of hemorrhage.1 The technique to use the clip applier is to place the jaws of the clip applier around the tissue to be ligated and when activated compress the clip into its closed position.2 Important features of the clip design are the serrations on the concave surface of the clip to reduce the likelihood of
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the clip slipping off the vessel.2 Application of the clips requires visualization of both sides of the clip to ensure that adequate tissue is penetrated and to prevent inadvertent clipping of nontarget tissues.2 Absorbable clips are also available. These clips are usually made of polyglycolic acid polymers.2 These clips have identical ligation properties but can cause adhesion formation.2 Ischemic necrosis can occur when the metallic clips are placed very close to the bowel wall, resulting in stricture or perforation.2 Complications can hopefully be prevented by adequate visualization of the vessels and structures before application of the clip. Instead of using the clips, another type of ligature such as the loop ligature may be more appropriate.
LINEAR STAPLING DEVICES Linear stapling devices are primarily used for performing anastomosis but they can be important when used to prevent major hemorrhagic complications.2 For large vessels or thick broad tissue planes, the tissue planes can be readily resected; a disposable endoscopic stapler is an excellent means of achieving hemostasis and tissue apposition.1
ENDO LIGATURES The pre-tied suture loops with slip knots have a limited use in primary hemostasis because the vessel or vascular pedicle must first be divided, grasped, and then secured.2 Using the pre-tied loop would leave a bleeding vessel while placing the loop.2 The pre-tied loops are ideally suited for well-isolated pedicles such as a cryptorchid testicle. There is a manufactured, pre-tied suture loop called the Endoloop. The Endoloop is a preformed knotted loop with a sliding knot at the end of a disposable nylon cannula that is designed to fit over vascular pedicles and then tightened.1 Endoloop ligatures are available in chromic gut, polydioxanone (PDS II) suture, coated Vicryl (polyglactin 910) suture, Monocryl (poliglecaprone 25) suture, and Ethibond Excel polyester suture.1 When using the Endoloop, the introducer sleeve is placed through a trocar into the abdomen. The loop is then advanced into the field of view and placed in proximity to the pedicle to be ligated.1 The vessel or pedicle that is to be ligated is then isolated by dividing and separating surrounding peritoneum and connective tissue.5 The suture can then be placed around the pedicle with a grasping forceps stabilizing the tissue.5 The jaws of a grasping forceps are passed through the loop to hold the pedicle and draw the tissue into the loop of the ligature.1,5 Once the loop is in position, the plastic knot pusher is broken at its scored end outside the body.1 The short end of the pusher is pulled while the long section is advanced through the trocar to close the loop tightly around the pedicle.1 Most normal-sized ovaries and testicles fit
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within the loop of the Endoloop.1 One of the disadvantages is the short length of the knot pusher, making it difficult to use in standing surgery through the paralumbar fossa.1 There are two types of laparoscopic ligatures: intracorporeal and extracorporeal. The intracorporeal and extracorporeal pre-tied laparoscopic knots are very useful for vessel ligation. Because tying of intracorporeal knots is difficult, pre-tied knots for encircling ligatures have been developed.11 An excellent technique for laparoscopic extracorporeal tying was developed in 1971 by Dr. H. Courtenay Clarke, using a knot pusher to secure the knot in a manner very similar to the way one would hand-tie sutures at laparotomy.5 It is much easier to tie laparoscopic knots outside of the body, where the surgeon can see the knot tying (extracorporeal). The extracorporeal ligatures are placed through a 5-mm diameter plastic sheath, which helps to introduce the ligature into the body cavity and acts as a knot pusher.5,11 These knots are one of the fundamental knots of laparoscopy and are used primarily for ligation of pedicles and tissue approximation.1 When the ligatures are passed around a clearly dissected vessel, careful attention must be adhered to so as not to saw the tissue or vessel as the ligature is being passed.2 The extracorporeal surgeon’s knot is the easiest to tie because the knot is tied outside the body in exactly the same way that it is tied in open surgery.1 Another extracorporeal slip knot is the Roeder knot. It is one of the most useful slipknots used in laparoscopic surgery. The advantage of the Roeder knot is that it is rapidly tied and is easier to advance to the specific site on the tissue than the extracorporeal surgeon’s knot.1 The suture material itself makes a difference when tying the Roeder knot. Using polydioxanone or other monofilament suture is not recommended for tying the Roeder knot. The specific properties of the monofilament suture material may cause the knot to slip.1 If monofilament suture is used, the Roeder should not be used and the modified Roeder knot should be used. The modified Roeder allows for increased friction and decrease knot slippage.1 Because of the additional friction created by the modified Roeder knot, the choice of suture material should be taken into consideration. Natural catgut and Vicryl suture are two of the suture materials that should not be used.12 Extracorporeal knots have distinct advantages over intracorporeal laparoscopic slip knots when only single ligatures need to be applied.1 Intracorporeal suturing techniques create knots entirely within the body cavity and enable the surgeon to ligate and perform a simple interrupted or continuous suture pattern.1 The intracorporeal square knot is tied the same way as the traditional square knot. The difference is that the two instruments are used to handle the suture within the abdomen.1 Needle holders and graspers with locking mechanisms greatly facilitate the
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process of intracorporeal suturing and knot tying.1 Intracorporeal suturing is very difficult to master and is a challenging skill to learn. The surgeon should practice before using the intracorporeal knot in the surgical setting. When it is necessary to use a needle or to pass a ligature around a vessel that is not free from surrounding tissue, the Endoknot product may be used.1 The Endoknot is a suture attached to a straight needle at one end and a disposable nylon cannula at the other. The needle and cannula are introduced and the needle is passed around or through the structure to be sutured.1 The needle is brought out of the trocar and an extracorporeal Roeder knot is tied and advanced to the tissue site, using the nylon cannula.1 It is the surgeon’s preference as to which suture material use. Yet many features are important when choosing the type of suture. How well the suture handles, friction, and knot security are all important characteristics to consider when choosing the suture material. Some prefer polydioxanone because of its memory or rigidity, which keeps the loop open and the knot sliding easily. Size 1 Maxon in a 4-S modified Roeder knot provides knot security superior to that of commercially available knots.13
REFERENCES 1. Newman RM, Traverso LW. Principles of laparoscopic hemostasis. In: Scott-Conner CE, ed. The sage’s manual fundamentals of laparoscopy and GI endoscopy. New York: Springer; 1999:57–68. 2. Fischer AT Jr. Equine diagnostic surgical laparoscopy. Philadelphia: W.B. Saunders; 2002. 3. Lantis JC, Durville FM, Connolly R, Schwaitzbury SD. Comparison of coagulation modalities in surgery. J Lap Adv Surg 1998;8:381–394. 4. Laycock WS, Hunter JG. Electrosurgery and laser application. In: MacFadyen BV Jr, ed. Operative laparoscopy and thoracoscopy. Philadelphia: Lippincott- Raven; 1996:79–91. 5. Burke RK. Electrosurgery: clinical and comparative concepts. In: Cohen SM, ed. Operative laparoscopy and hysteroscopy. New York: Churchill Livingstone; 1996:37–51, 119 120. 6. Brunicardi CR. Minimally invasive surgery. In: Brunicardi FC, ed. Schwartz’s principles of surgery. New York: McGraw Hill; 2005:389–392. 7. Airan MC, Sung-Tao Ko. Electrosurgery techniques of cutting and coagulation. In: Arregui ME, ed. Principles of laparoscopic surgery, basic and advanced techniques. New York: Springer Verlag; 1995:30–33. 8. Tucker RD, Platz CE, Sievert CE, Vennes JA, Silvis SE. In vivo evaluation of monopolar versus bipolar electrosurgical polypectomy snares. Am J Gastroenterol 1990;10:1386–1390.
SUMMARY The best plan is a surgical procedure that is well thought out ahead of time. Organization and prioritization of the surgical steps from beginning to end are essential. Once the procedure has started, adequate visualization and identification of all structures before dissection saves time and produces a better outcome. Rapid or mishandled tissue often results in nuisance bleeding that may obscure the operative field and lead to an error. Electrosurgical instruments should be safely applied to the vessel to be ligated before its dissection, helping to prevent uncontrolled hemorrhage. When active bleeding occurs, having thought out the steps needed to remedy the situation is essential. Surgeons should be no different from the pilot who regularly reviews contingency plans for an emergency situation.
9. Bhoyrul S, Mori T, Way LW. Principles of instrumentation. In: Way LW, ed. Fundamentals of laparoscopic surgery. New York: Churchill-Livingstone; 1995. 10. Centers for Disease Control and Prevention. Deaths following female sterilization with unipolar electrocoagulating devices. Morbid Mort Weekly Rep 1981;30:149. 11. Thompson SE, Potter L. Electrosurgery, lasers and ultrasonic energy. In: Freeman LF, ed. Veterinary endosurgery. St Louis: Mosby; 1999. 12. Hendrickson DA. History and instrumentation of laparoscopic surgery. Vet Clin North Am, Equine Pract 2000;16:233–249. 13. Stoloff DR. Laparoscopic suturing and knot tying techniques. In: Freeman LJ, ed. Veterinary endosurgery. St Louis: Mosby; 1998. 14. Shettko DL, Frisbie DD, Hendrickson DA. A comparison of knot security of commonly used hand tied laparoscopic slipknots. Vet Surg 2004;33:521–524.