Techniques Prof. Dr. R. K. Mishra INTRODUCTION Dissection is defined as the separation of tissues with hemostasis. It consists of a sensory visual and tactile component, an access component involving tissue mani pulation, and instrument maneuverability. These are combined to achieve exposure, i.e., developing a suitable space for seeing and handling target structures. Precision and meticulous hemostasis is essential requirement in minimal access surgery (MAS). Endoscopic dissection, in contrast to dissection in conventional surgery, possesses several limitations. Threedimensional direct visions are replaced by twodimensional indirect visions in laparoscopic surgery. Illumination and the video image quality are still limited despite recent advances in video systems such as digitization and threechip endocamera. Movement of the functional tip of laparoscopic instruments is restricted along with the kinematics response. The loss of tactile sensation in endoscopic surgery is yet another limiting factor. Endoscopic dissection and manipulation of tissue within a confined space require a twohanded approach, assisting and dissecting both task are performed by surgeon himself. A passive assisting instrument (usually a grasper) provides countertraction and exposure for the active dissecting instrument. The active instrument may be nonenergized (e.g., scissors and scalpel) or energized with electricity (diathermy), ultrasound, or light energy. TYPES OF LAPAROSCOPIC DISSECTION A variety of mechanisms have been used to divide tissue and enable hemostasis. They all involve some form of physical energy being applied to the appropriate tissue. The amount of energy required for dissection depends on the type and constituency of the tissue. The properties of tissues may vary in different directions and for different disease states. This in totality influences the choice of the modality for dissection. The ideal dissection technique requires a modality that can accomplish meticulous hemostasis and will be tissue selective without causing inadvertent tissue damage. It must be safe for both patient and surgical team when in regular use and when inactive in storage. In this respect, builtin safety measures are mandatory. An ideal dissecting modality should be efficient in both power delivery and in space requirement. The modality must be costeffective also. The initial expenditure needed to acquire and setup the necessary equipment must be taken into account along with subsequent operational and maintenance costs. In reality, there is no single “ideal” dissecting modality for entire minimal access surgical procedures. In actual practice, a combination of energy forms is applied with selection of the most appropriate one at each particular phase or type of the operation. The available modalities for dissection in MAS include: ■ Blunt dissection ■ Sharp scalpel and scissors dissection ■ Highfrequency radiowave electrosurgery ■ Radiofrequency ablation ■ Ultrasonic dissection ■ Highvelocity and highpressure waterjet dissection ■ Laser surgery Blunt Dissection Instrument Used ■ Closed scissors tips used as blunt dissector ■ Scissor points used to separate by spreading the jaw ■ Grasper—straight and curved ■ Inactive suction cannula ■ Heel of inactive electrosurgery (hook or spatula) ■ Pledget Methods ■ Distraction ■ Separation ■ Teasing ■ Wiping Pledget Dissection Endoscopic pledget dissection was first introduced in the University of Dundee in 1987. A special endoscopic pledget or peanut swab 5.0 mm ratcheted holder, manufactured by Storz (with strong jaws and inward facing tongs at the
SECTION 1: Essentials of Laparoscopy end of the jaws for security), is used in a manner similar to that employed in open surgery. The holder grasping, the pledget, is introduced inside a reducer tube through an 11.0mm cannula. The blunt dissection is safe and is used to open planes and expose structures especially when the anatomy is obscured by adhesions. The movement consists of forward and backward wipes accompanied by clockwise/ counterclockwise rotation of the pledget swab. It is also useful for controlled small bleeder by compressions before this is secured by clipping or electrocoagulation. The pledget swab is particularly useful for blunt dissection in Calot’s triangle during cholecystectomy. It is economical, simple to use, and maintains a dry operative field while performing dissection. This type of dissecting modality is also utilized in hemostatically separating gallbladder from its bed, bladder from the uterus, or the rectum from the sacral attachment (Fig. 1). Removal of pledget must be carried out under vision to ensure that the swab is inside the reducer tube before withdrawal of the instrument, otherwise there is a real risk of losing the small pledget swab in the peritoneal cavity. The pledget is an invaluable tool for the rapid dissection of loose areolar planes when it is wiped or pushed against the line of cleavage to separate the tissues. Pledget is useful in maneuvers to control minor hemorrhage. The pledget can be placed over the bleeding point to apply pressure. When used on an oozing operative field, it adsorbs some of the blood and may clarify the anatomical position. It is important to follow routine practice to minimize loss of the peanut swab inside the abdomen: ■ Always use a reducer tube to insert and remove the swab. ■ Employ a safe system (ratchet and elastic band) to maintain the grip of instrument used for insertion. ■ Keep the pledget in view from insertion to retraction into the introducer tube. Be sure it is retrieved into the introducer, not the cannular end. Fig. 1: Pledget dissection. Tissue Stripping and Tissue Distraction These are other safe and effective forms of blunt dissection. The latter is applied for seromyotomy. Insignificant hemostatic capability is the main disadvantage of blunt dissection (Fig. 2). Sharp Dissection Sharp scalpel is used mainly for division by cutting. Although inexpensive, its use is restricted in laparoscopic surgery. The lack of hemostasis, the potential of injury from the tip when inserting through the port, and the kinematics problems restrict its use to common bile duct division. Scissors Dissection It is one of the most frequent methods in laparoscopic surgery. It offers the benefits of being cheap, safe, and precise operator determined action. However, being nonhemostasis renders it far from ideal as a dissecting modality (Fig. 3). Electrosurgical Dissection Electrosurgery is the most convenient way of dissection in MAS combined with most risky method of dissection. Most of the complication in laparoscopic surgery is due to use of energized instrument (1%) (Fig. 4). Before understanding the principle of electrosurgery, following definitions should be known: ■ Current: Flow of electrons ■ Circuit: Pathway for flow of electrons ■ Voltage: Force that causes electron to flow ■ Resistance: Obstacle to the flow of electron. There are two basic principles of electricity: 1. Electrical current ultimately flows to ground 2. It always follows the path of least resistance. Fig. 2: Tissue stripping and dissection.
Fig. 3: Scissor dissection. Fig. 4: High-frequency electrosurgical generator. High-frequency Electrosurgical Dissection Our household appliances have the 50–60 Hz frequency. This frequency is beneficial because if faulty instrument has current and inadvertently someone touches, then he will be thrown away and the person getting shock will be safe. If the frequency is >100 kHz, muscle and nerve stimulation ceases whereas all other property of electric current is still there. Highfrequency electrosurgery is the application of highfrequency currents (in the frequency range of 300 kHz up to several MHz) to coagulate, fulgurate, spray coagulates, or ablates tissue. Knowledge of how this and other physical modes interact with biological materials is becoming increasingly important to the surgeon for safe and consistent surgery (Fig. 5). ■ Standard electrical current alternates at a frequency of 50 cycles per second (Hz) ■ Nerve and muscle stimulation ceases at 100,000 cycles per second (100 kHz) ■ Electrosurgery can be performed safely at frequencies above 100 kHz. High-frequency Monopolar Electrosurgery The monopolar circuit is composed of the generator, active electrode, patient, and patient return electrode. The patient’s tissue provides the resistance, producing heat (Fig. 6). Monopolar diathermy is used in endoscopic surgery for coagulation and for dissection (cutting). During monopolar diathermy, current is conducted from the instrument through the tissues to a skin pad (neutral electrode) connected back to the generator. Heating occurs at site of small crosssection and low electrical conductivity. A high current density occurs in the tissue in immediate contact with the instrument and heat is generated. Burn = Intensity of current × Time/area Burn is directly proportional to the intensity of current. Intensity of current can be adjusted by the knob provided in Fig. 5: Frequency range of electrosurgery. the generator’s control panel. If the intensity setting is more, the burn will be more. Intensity actually denotes ampere or number of electrons that flows through the pathway. Burn is also directly proportional to time. Time is paddle application time. Surgeon should always keep in mind that continuous activation of paddle can result in many complications. Intermittent activation is always better than continuous activation (Figs. 7 and 8). Burn is inversely proportional to area. One of the major problem in electrosurgery is patient will get burn at the site where area is narrowest. This may cause remote injury with the use of monopolar diathermy. The surgeon should hold the tissue with the point of instrument to catch the minimum amount of tissue at one time. If a bunch of tissue is caught, there is always fear of remote injury. Patient return electrodes: Silicon and metal patient return plates are available. The silicon is better because it does not have any sharp edge and the resistance is less (Fig. 9). Patient return electrode is required only in unipolar electrosurgery because the patient’s body is a part of circuit and the patient return plate will take the current back to the generator. If the patient return plate is not attached properly 111
SECTION 1: Essentials of Laparoscopy Fig. 6: Circuit of monopolar current. Fig. 7: Remote injury. Fig. 8: Remote injury with electrocautery device. Fig. 9: High-quality patient return plate. to the body of the patient or the size of the patient return plate is very small, patient can get electric burn at the point of attachment of this patient return plate. Ideally, the size of patient return plate should not be <100 cm2. At the time of location of patient return plate attachment, surgeon should keep in mind the following points (Fig. 10): ■ Choose: Wellvascularized muscle mass to have more area of contact. ■ Avoid: z Vascular insufficiency should be avoided because of high resistance z Irregular body contours can prevent plate to be in firm contact z Bony prominences will not allow the surrounding skin to be in contact. ■ Consider: z Plate should be nearer to incision site z Plate should be placed according to patient’s position, so it should not be displaced z Plate should be away from other equipment such as cardiac monitor. Fig. 10: Patient return plate. The effect of highfrequency current on the tissues depends on: ■ Temperature generated ■ Shape and dimensions of the contact point (broader damage with broader contact)
■ Time of activation (short bursts reduce depth and ■ Current path is confined to tissue grasped between forceps (Fig. 13) charring) ■ Distance from the electrode (Fig. 11) ■ Conductivity of the tissue (bleeding results in a change in conductivity) ■ Power output from the generator (voltage) ■ Amplitude and current wave form time curve of the signal (cutting or coagulating settings). Bipolar Diathermy A bipolar system is inherently safer as the interaction is restricted to the immediate vicinity of contact and the current does not pass through the patient, but instead returns to the generator via the receiving pole after passage through the grasped tissue (Fig. 12). Bipolar Electrosurgery ■ Active output and patient return functions both are at the site of surgery ■ Return electrode should not be applied for bipolar procedures. Tripolar Electrosurgery Bipolar probes are now available for coagulation as well as for cutting. The cutting system is not strictly bipolar and is hence referred to as tripolar (Fig. 14). It has four functions in one and the same instrument namely: 1. Dissecting 2. Grasping 3. Bipolar coagulation 4. Bipolar cut Use of the Diathermy Hook These are generally Lshaped or open Cshaped, blunt ended rods mounted on an insulated handle. The active, noninsulated part is limited in size. The hook is a delicate Fig. 11: Effect of cutting current. Fig. 12: Circuit of bipolar current. Fig. 13: Bipolar forceps used in laparoscopically-assisted vaginal hysterectomy (LAVH). Fig. 14: Tripolar device. 113
SECTION 1: Essentials of Laparoscopy instrument and should be protected during insertion by manual opening of the cannula valve or use of a reducing tube. As electrosurgery generates smoke (which is harmful), many handles of electrosurgical hooks have a suction attachment at the other end of the handle. Electrosurgical Hooks (Fig. 15) Electrosurgical instruments such as the hook are useful as blunt dissectors prior to activation. They are used to isolate the tissue to be divided by the current. The tip is passed into or under a layer of the tissue being dissected, which is then hooked and tented up (to increase its impedance and thus limit the spread of current when applied). Small portions of tissue are tackled, so that an assessment of the tissue caught on the hook can be made before coagulation or cutting current is applied to the instrument. The hook can be used to clear unwanted tissue beside linear structures by passing the hook into the tissues parallel to the structure and then rotating it to hook up strands of unwanted tissue. The tissue Fig. 15: Different types of hook. to be divided is held away from underlying tissue to prevent inadvertent damage. Short bursts of coagulating current can be followed by the use of cutting current, if the tissue has not already separated. The use of the hook can be summarized as “hook, look, and cook” . The hook or the spatula may be used to mark out and coagulate a line for division. The heel of the hook is used with the highfrequency current set to soft coagulation. Short bursts are applied and the hook moved along to create a “dotted” line of coagulated tissue. When deeper penetration is desired, the hook is appropriate instrument. This type of contact is best reserved for situation where no significant damage can be caused by current penetration (Fig. 16). Monopolar electrosurgery has become the most widely used cutting and coagulating technique in MAS. It has proven to be versatile, costeffective, and demonstrated superior efficacy for coagulation. By varying the voltage, current, or waveform, tissue can be cut cleanly (pure cut); coagulated to achieve hemostasis (coag mode) or a “blend cut” that combines these two functions can also be produced. Finally, a dispersed coagulation mode known as fulguration allows coagulation of diffuse bleeding (Fig. 17). Cutting current is lowvoltage highfrequency current. Due to high frequency, the ions inside the cell get turbulence and cells brust (explode or evaporize). Cutting current can be obtained by pressing the yellow paddle of electrosurgical generator. To cut any structure, it is important that surgeon should apply the sharp tip of electrosurgical instrument and the tissue should not be held firmly. At the time of cutting, it is wise that tissue should be under tension. Ideally, direct touch with the tissue should be avoided in case of cutting current. It should be spark wave from some distance (Fig. 18). Electrosurgical coagulation is achieved by highvoltage lowfrequency current. This low frequency is not sufficient to cause the explosion of cell, but heat inside the cell is increased. Fig. 16: Depth of desiccation is proportional to paddle application time.
Fig. 17: Different types of electrosurgery. Fig. 18: Fulguration. Fig. 19: Desiccation with more collateral damage. Fig. 20: Desiccation with less collateral damage. Due to increased intracellular temperature, the protein inside the cell coagulates and shrinks. Shrinkage of protein will cause constriction in the lumen of bleeding vessels and the vessels are sealed. Permanency of coagulated tissue and its sealing effect depends upon melted collagen. At the time of electrosurgical monopolar coagulation, the temperature of tissue causes the collagen to melt. These melted collagens solidify again once the active instrument is off from the tissue. It is important to remember that if the tissue is burnt more than required, the melted collagen burns, turns into charcoal, and the sealing strength of the lumen of any vessel will decrease. Surgeons and gynecologists should always try to avoid overcooking of the tissue. more than depth. We want to use fulguration everywhere, where superficial burn is required and deeper injury may cause damage of underlying structure. The example of good use fulguration is ablation in cases of endometriosis and fulguration of gallbladder bed at the time of cholecystectomy, if there is generalized oozing from liver. Direct touch with tissue should be avoided to achieve maximum effect. Fulguration is coagulation current from some distance. 2. Desiccation: Electrosurgical desiccation occurs when the electrode is in direct contact with the tissue. Most of the time with the unipolar or bipolar electrosurgery, we do desiccation only. The tissue damage in depth and width is same in desiccation. The extent of collateral damage in desiccation is more compared to cutting current. The extent of collateral damage of desiccation can be minimized by minimizing the paddle application time (Figs. 19 and 20). Electrosurgical coagulation is of two types: 1. Fulguration: Fulguration is coagulation current from some distance (Fig. 18). It is also known as spray mode. At the time of fulguration, lateral spread of energy is 115
SECTION 1: Essentials of Laparoscopy However, monopolar laparoscopic electrosurgery can compromise patient safety under certain circumstances. Thermal injury to nontargeted internal organs may occur firstly, as a result of imprecise mechanical operation of a laparoscopic instrument and secondly, through diversion of electrical current to other paths. These stray current may be released either through insulation failure, direct coupling, or capacitive coupling. Other problems encountered include effect on pacemakers, return electrode burns, toxic smoke, charring of instruments, and minimal control of energy delivery (Fig. 21). Bipolar electrodes design although virtually eliminating complication from insulation failure, capacitive coupling, and direct coupling (Figs. 22 to 24). The primary electrothermal tissue effect is limited to desiccation, not cutting. It requires slightly more time than monopolar coagulation because of lower power settings and bipolar generator output characteristics. It is not an effective method of making a “pure cut” . ■ Hemostasis over a large area is not possible ■ Grasping dense tissue between both the active and return electrodes is difficult. Safety during Electrosurgery Laparoscopic dissection requires more extensive dissection and thus meticulous hemostasis becomes particularly important. Any loss of view will result in loss of control and hence decreased safety. Hemorrhage, even to a minor extent, tends to obscure their operative field and is to be avoided. This means that vessels of a size that in open surgery could be divided without particular attention need to be secured prior to division when working endoscopically. Dissection must be more meticulous to proceed smoothly to avoid any unacknowledged injury. The magnification produced by the endoscope may initially confuse the surgeon as to the extent of electrical injury. However, an inexperienced endoscopic surgeon is welladvised to convert if he have any doubt about his ability to control the situation expeditiously. Safety Considerations in Minimal Access Surgery Fig. 21: Overshooting should be avoided. A The potential for accidental damage with electrosurgery must always be borne in mind at the time of MAS. Following are the most commonly encountered problems specific to the MAS: ■ Overshooting ■ Overcooking ■ Direct coupling ■ Capacitive coupling ■ Insulation failure B Figs. 22A and B: Direct coupling.
Fig. 23: Capacitive coupling. Overshooting: Overshooting means the tip of energized instrument going beyond the field of vision during electrosurgery. Overshooting is one of the common mistakes done by beginners. Surgeon should be careful that if they are cutting any structure they should apply less force, otherwise their instrument will overshoot once the structure is cut and the energized instrument can heat any nearby viscera leading to perforation. During initial learning phase of laparoscopy, the trainer surgeon should keep hold on the hand of trainee at the time of electrosurgery to prevent any inadvertent injury by overshooting. At the time of laparoscopic cholecystectomy, if hook overshoots, it may hit diaphragm or duodenum. If overshooting is not under the control of surgeon, he should try to keep the tip of hook toward the anterior abdominal wall, so that only peritoneum will be injured. Overcooking: Proper hemostasis requires optimum application of energy over the tissue. Due to visual limitations and fear of impending bleeding, laparoscopic surgeons have a tendency of overcooking. It is important to remember that instead of more secure coagulation overcooking can create rebleeding. To understand the effect of overcooking, it is important to know physiology of tissue sealing. Coagulation current is highvoltage lowfrequency current. At this current, the ions inside the cell will move but it cannot explode. Due to increase in intracellular heat, the protein inside the cell will be denatured, coagulated, and shrink. Due to shrinkage of tissue, the lumen of small bleeder obliterates and bleeding stops. At the same time due to heat, the collagen of tissue melts and once the paddle of electrosurgical generator is off, the melted collagen will cool down and solidify. Overcooking results in charring of melted collagen and the sealing strength of tissue is decreased. It could be understood just by the example of sealing of polythene over a flame of candle. If you want to seal the polythene bag but applying more temperature on polythene by putting it over direct flame, instead of getting sealed, the polythene will start burning. One should know the sealing temperature of polythene so that required temperature is applied, the Fig. 24: Burn due to capacitive coupling. polythene will melt and once cooled will solidify. Similarly, the burnt collagen does not have any tissue sealing property and bleeding may start again if it is overcooked. Most common causes of overcooking or charring of tissue are: ■ High power setting of electrosurgical generator ■ Prolonged activation of foot paddle ■ Keeping the jaw closed permanently in contact of tissue ■ Poorly engineered electrosurgical generator. Direct coupling: If the active electrode touches a noninsulated metal instrument within the abdomen, it will convey energy to the second instrument, which may in turn, if the current density is high enough, transfer it to surrounding tissues and cause a thermal burn. For example, the active electrode could come in contact or in close proximity (<2 mm) to a laparoscope, creating an arc of current between the two. The laparoscope could then brush against surrounding tissue, causing a severe burn to the bowel and other structures. The burns may not be in the visual field of the surgeon and therefore will not be recognized and dealt with in a timely fashion. To prevent direct coupling, the active electrode should not be in close proximity to or touching another metal instrument before the generator is activated. Bowel is particularly susceptible to this kind of collateral damage from sparks and stray currents. Recognition of this complication may be delayed until the postoperative period with serious consequences. Check that the electrode is touching the target tissue, and only that tissue, before you activate the generator. Note that when target tissue is coagulated (desiccated), the impedance increases and the current may arc to adjacent tissue, following the path of least resistance. We should be careful that all metal instruments such as laparoscopes pass through conductive metal trocars. This way, if the active electrode touches the instrument, the 117
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