Chapter 4. Fundamentals of Laparoscopic Surgery

Tremendous growth in the use of minimally invasive techniques has occurred over the past decade. This was made possible by developments in technology and was fueled by patient demands for less painful operations and quicker postoperative recovery.

Almost all general surgical procedures can be performed using minimally invasive techniques. The greatest benefit is achieved in operations where the trauma of access exceeds that of the procedure. Procedures in the chest, upper abdomen, and pelvis, especially those not requiring tissue removal, are ideally suited for minimally invasive techniques. Conversely, other procedures may have less obvious benefits when performed with minimally invasive techniques, especially if a large specimen is to be removed. To be a proficient laparoscopist, one must become familiar with a new set of techniques and instruments, as well as knowing when to apply them and when to convert to an open operation.

Patient Selection

As in all surgery, choosing the right operation for the patient is the first step. Since all laparoscopic surgery of the abdomen requires the use of general anesthesia, the ability to tolerate anesthesia is an absolute requirement. Patients with impaired exercise tolerance or a history of shortness of breath will need a preoperative consultation with a cardiologist or pulmonologist. Patients with severe carbon dioxide (CO2) retention can be difficult to manage intraoperatively because the use of carbon dioxide for pneumoperitoneum exacerbates the condition. By increasing the minute ventilation and decreasing the CO2 pneumoperitoneum from 15 to 8–10 mm Hg, one can control metabolic acidosis. Rarely, when these measures are ineffective at controlling hypercarbia, we have resorted to using nitrous oxide (N2O) for peritoneal insufflation. While not suppressing combustion (as does CO2), N2O supports combustion no more than air and has been proven safe for laparoscopic use. A single blind randomized trial has demonstrated that N2O pneumoperitoneum is associated with decreased postoperative pain compared with CO2.1

When deciding if a patient is a suitable candidate for a laparoscopic procedure, it is important to assess patient or procedure characteristics that will lengthen the operative time sufficiently to nullify the benefits of laparoscopy. If the laparoscopic operation takes substantially longer than the open equivalent or is more risky, then it is not prudent to proceed laparoscopically. A history of a prior open procedure or multiple open procedures can make access to the abdomen difficult and will be discussed in detail later in this chapter. Adhesions and scarring in the surgical field from prior surgery can make laparoscopic surgery very difficult and may require use of many novel dissecting and coagulating tools. Operating on patients with severe obesity is challenging specifically because torque on transabdominal ports leads to surgeon fatigue and diminishes surgical dexterity. In addition, the long distance from the insufflated abdominal wall to the abdominal organs can make laparoscopic surgery a “far reach.” Special long ports and instruments are available to overcome this difficulty.

Inability to obtain an adequate working space makes laparoscopic surgery impossible. This is encountered most commonly in patients with dilation of the intestine from bowel obstruction. Often, laparoscopic lysis of adhesions for distal bowel obstruction is not technically feasible.2 Some patients with appendicitis will have sufficient small bowel dilation that laparoscopic access to the right iliac fossa is not possible.

Patient Positioning

We rely on gravity for retraction of the abdominal contents to provide exposure. Sometimes this requires steep positional changes, and care must be taken to prevent nerve complications or neuropathies after laparoscopic surgery as in open surgery. Patients must be positioned properly at the beginning of the procedure, making certain that all pressure points are padded. Perineal nerve injury is caused by lateral pressure at the knee and may occur when the table is “airplaned” to the side with a retractor holding the patient in place. Femoral and sciatic neuropathies are similar in that they are due to compression. Padding the retractor arms and securing the patient to the table can prevent these neuropathies.

It is best if the arms can be tucked for most laparoscopic procedures so that the surgeon may move freely up and down the table in order to line up instruments and the target tissue. This is most important for procedures in the pelvis, where the surgeon will want to stand adjacent to the contralateral thorax. However, even with upper abdominal laparoscopy, tucked arms allow more optimal positioning of instrument columns and monitors. If there is a need to extend the arms on arm boards, one must be very careful to avoid a brachial plexus injury that occurs when the arm is extended greater than 90 degrees at the shoulder. Usually, at the start of a procedure, the arm positioning is safe but may change as the patient slides down on the table. For this reason, when reverse Trendelenburg is expected, we place footplates at the feet. This prevents sliding on the table and does not cause any discomfort to the patient because it is much like standing. We secure the ankles as well to be sure they do not “twist” during the procedure. There are footplates available for split-leg tables that can be used when operating on the upper abdomen and steep reverse Trendelenburg is needed.

Patient Preparation

There may be an increased incidence of deep venous thrombosis after laparoscopic surgery that is due to pooling of blood in the venous system of the lower extremities. Venous return is impaired by compression of the iliac veins from the elevated intraabdominal pressure exerted by the pneumoperitoneum. Additionally, the positional effects of placing the patient in a steep reverse Trendelenburg position lead to further distension of the venous system. All patients undergoing laparoscopic procedures in reverse Trendelenburg, even short procedures such as laparoscopic cholecystectomy, should have sequential compression devices placed before the procedure begins, although this does not improve femoral blood flow entirely.3 Patients at high risk for developing deep venous thrombosis should be treated with subcutaneous anticoagulants as either fractionated or unfractionated heparin.4 This includes patients undergoing lengthy procedures, obese patients, patients with a prior history of deep venous thrombosis or pulmonary embolism, and patients in whom ambulation after surgery will be delayed. Some authors recommend placement of vena caval filters in patients with a prior history of deep venous thrombosis who are undergoing lengthy laparoscopic procedures.5

Laparoscopic surgery is associated with a high incidence of postoperative nausea and vomiting. A recent review asserts that serotonin receptor antagonists such as ondansetron (Zofran, GlaxoSmithKline) appear to be the most effective and should be considered for routine prophylaxis.6 Another prospective, blinded, randomized trial shows a decrease in the postoperative nausea and vomiting when low-dose steroids are given to all patients.7 There was no increased infection rate in the group that received steroids. Other preventive measures include ensuring adequate hydration8,9 and decompression of the stomach with an orogastric tube before the end of the procedure. Intravenous nonsteroidal anti-inflammatory drugs (NSAIDs) such as ketorolac provide superb pain relief and diminish the need for postoperative narcotics, which may help to prevent nausea and vomiting.

Site Selection

Proper placement of ports is important to facilitate completion of the laparoscopic procedure. The location of port sites depends on the type of procedure; the primary port should be placed with this in mind. We do not always place the primary port at the umbilicus but rather judge which site is best for the camera or which is the safest site for the primary puncture in a previously operated abdomen. The first laparoscopic port can be positioned anywhere in the abdomen after pneumoperitoneum has been created. The additional or secondary ports should not be placed too close to each other. The optimal pattern of port placement should form an equilateral triangle or a diamond array around the operative field. This “diamond of success” takes into account the optimal working distance from the operative target for each instrument and the telescope (Fig. 4-1). In laparoscopy, the standard instrument length is 30 cm. To produce a 1:1 translation and movement from the surgeon's hands to the operative field, the fulcrum of the instrument should be 15 cm from the target. A similar separation of the two working ports (surgeon's left and right hands) ensures that these two instruments will not be involved in “sword fighting” and that the angle between the two instruments at the target will be optimal (between 60 and 90 degrees). The secondary port site is chosen, and the abdominal wall is transilluminated to avoid large abdominal wall vessels.10,11 The trocar is watched laparoscopically as it enters into the abdomen, and care is taken to avoid injuring the abdominal contents. During the procedure, the area beneath the primary trocar site is inspected for unexpected injuries.

Port Characteristics

There is a wide variety of ports, each with different characteristics, available on the market. The bladed trocars cut the abdominal wall fascia during entry. Because the nonbladed trocars do not cut the abdominal wall as much, they make smaller defects in the abdominal wall and may be less prone to hernia formation in the future. The most commonly used bladed ports have a shield that retracts as the blade is pushed through the fascia of the abdominal wall, and then it engages once inside the abdomen. When first introduced to the market, the shields were called safety shields, but they have lost that designation because the shield provides little protection. The nonbladed trocars come in many forms. One nonbladed trocar is used in the Step system (Covidien, Mansfield, MA), a modified Veress needle that locks inside an expandable sheath. Once inside the abdomen, the Veress needle is removed, and a blunt port is passed into the sheath that guides the port by dilating radially.12 The Ethicon nonbladed trocar has a rough edge of plastic that is twisted and pushed through the layers of the abdominal wall. None of these technologies have proven safer than the more economical reusable nonshielded bladed trocar systems made by most instrument companies (Fig. 4-2).

Important characteristics of a port need to be considered when choosing which port to use. The advantage of a port introduced with a nonbladed trocar is that the abdominal wall defect is smaller, which does not allow gas to leak from the abdomen during the procedure. Because the fascia is not cut, there is a lower risk of port-site hernia, and the fascia of most 10-mm incisions does not have to be closed. Additionally, these ports tend not to slip out of the abdominal wall during manipulation. Other considerations when choosing a port are the size of the external component, the smoothness of entry and exit of the instruments and specimens, and whether an external reducer cap is needed.

Access or Placement of the First Port

No single access technique has emerged as the safest and best technique.13,14 The techniques for abdominal access include direct-puncture and an open-access technique.15 The direct-puncture technique can be performed either by direct trocar insertion without pneumoperitoneum or by first obtaining pneumoperitoneum using a Veress needle and then inserting the first trocar directly. The latter technique is performed most commonly in the United States. Each technique has a specific pattern of complications that must be considered when choosing among them.

The Veress needle access was first described in 1938.16 This technique involves direct insertion of a needle into the peritoneum after lifting the abdominal wall with towel clips or a firm grip. The optimal site for insertion of the Veress needle is through the central scar at the umbilicus. One can make either a vertical skin incision through the umbilicus, hiding the incision in the base, or a curvilinear incision in an infraumbilical or supraumbilical position. Nevertheless, insertion of the Veress needle should be aimed at the central scar, where the layers of the abdominal wall are fused. This does not mean, though, that the first port inserted must be at the umbilicus. Advocates state that the benefits of this technique are the ability to place the initial port anywhere on the abdomen, that it is relatively quick, and that the skin and fascial openings are smaller, which prevents CO2 leakage during the procedure.

For safe Veress needle insertion, first one must be certain to check the stylet and needle patency, especially when reinserting it after an unsuccessful initial pass. The Veress needle is available either as a reusable or disposable product and comes in two sizes, both long and short. The spring mechanism that pushes the stylet out, thus protecting bowel from the needle, must be tested when using the reusable Veress needle.

The safest technique requires stabilizing the abdominal wall (we prefer penetrating towel clips in nonobese patients). It is important to have control over the force and depth of insertion of the needle. This is aided by either placing your wrist against the patient's abdomen or using the nondominant hand to support the hand wielding the needle. It is sometimes necessary to raise the operating table to achieve the proper control. One must be mindful of the fact that the most common catastrophic complication from Veress needle insertion is injury to major vessels. The trajectory of the needle should not be angled toward the aorta or iliac vessels (Fig. 4-3).

After placement of the Veress needle, one should perform an aspiration test by connecting a syringe filled with saline to the top of the Veress needle and aspirate. Aspiration of air, blood, or bile signifies incorrect placement and should prompt serious concern for an unexpected injury. If there is no aspirate, saline should be injected and should flow easily. The saline should flow down the Veress needle into the peritoneal cavity without pressure, a qualitative measure. Removing the plunger from the syringe and watching the saline level drop briskly may achieve a quantitative assessment of patency. If the saline flows slowly or not at all, the needle is likely in the wrong position, that is, up against an intra-abdominal organ, or it is in the preperitoneal space. Alternatively, the tip may be occluded with fat, or the system may have an “air lock.” To test this, inject a little bit of fluid again gently, and retest by removing the plunger and allowing the saline to drop into the abdomen.

The Veress needle then is connected to the insufflation tubing. The expected initial insufflation pressure, assuming proper placement, should be less than 5–6 mm Hg. Abnormally high insufflation pressure is an indication that something is not right.17 Because the insufflator is usually set to allow a maximum pressure of 15 mm Hg, a value greater than this suggests that the patient is not anesthetized adequately and is contracting his or her abdominal muscles. If the insufflator records a pressure of 15 mm Hg, there are a few explanations. The most ominous cause would be incorrect placement into an intra-abdominal organ. More likely, the Veress needle tip may be against omentum or is in the preperitoneal space. The insufflation line may be occluded at the stopcock, or there may be a kink in the tubing.

Direct trocar insertion without first establishing pneumoperitoneum is not used as frequently because many surgeons think that it is dangerous given that the bladed trocar must be pushed into the abdomen with significant force to penetrate the abdominal wall. Surgeons unfamiliar with the technique worry about injury to bowel and vessels when using excessive force. There are, however, many surgeons who perform this technique with no increased complication rate, confirming its safety.18–22 Still other surgeons believe that the open-access technique that involves a “minilaparotomy” is the safest.15,23–25

The open, or Hasson, technique was first described in 1974.15 A 1- to 2-cm skin incision is made at the umbilicus, and the soft tissue is divided to identify the abdominal wall. The fascia and muscles are opened with a knife, and the peritoneum is identified and grasped with Kocher or Allis clamps. A 0-0 absorbable suture is placed through the fascia, and the Hasson port is secured to the fascial sutures. Later, these sutures can be used to close the abdominal wall. The insufflation tubing is attached to the sideport of the trocar, and the abdomen is insufflated rapidly to 15 mm Hg.

Newer trocars, called optical trocars, allow visualization of the tip of the trocar as it passes through the layers of the abdominal wall (Fig. 4-4). A straight-viewing 0-degree scope is placed inside a clear trocar that is available with and without a bladed tip. Safe introduction of an optical trocar is a skill that requires judgment and experience and can best be learned in patients with no prior surgery after insufflation is established. Success depends on the operator's ability to see each of the layers of tissue, although visualization does not imply safety.26 It is useful for the surgeon to have command of several access techniques because there is no single technique that is best for all circumstances.27

Difficult Access

Access can be the most challenging aspect of the procedure in some patients no matter which technique is used. This is especially true in obese patients. First, the site of the central scar is often judged inaccurately because the umbilicus is in a caudad position owing to the loose panniculus. Additionally, there is an increased distance between the skin and the abdominal wall fascia. The Veress needle may not penetrate the abdominal wall. If an open-access technique is chosen, it may be difficult to expose the abdominal wall through a small incision. Degenerated fascia in obese patients will make the abdominal wall bounce against the needle or finger, making its identification difficult. Raising the skin with penetrating towel clips does not facilitate this exposure and, in fact, distorts the anatomy, making it more difficult to identify the fascia. Sometimes a modified technique described by Vakili and Knight can be helpful.28 This is a combination of open and Veress techniques in which a small skin incision is made in obese patients. Kochers are used to hold the abdominal wall fascia up, and a Veress needle is passed through the abdominal wall.

Access is also difficult in patients who have had prior surgery through a midline incision. In these patients, it is unsafe to perform the Hasson technique through the midline site because of the potential for adhesions of bowel to the posterior surface of the abdominal wall. Injury can occur when dividing the fascia or when sweeping adhesions away with a finger. It is difficult to perform the open technique at sites other than the umbilicus because of the multiple layers of the abdominal wall. In these patients, we prefer to place the Veress needle in the next safest location, which is the left upper quadrant along the costal margin. One must be certain that the table is flat because the spleen and liver are injured more easily in patients in the reverse Trendelenburg position. One must be certain that the stomach is decompressed with an orogastric tube before inserting the Veress needle in the left upper quadrant. Once insufflation is obtained, a port can be placed into the abdomen away from the previously operated field. We prefer entering with a 5-mm step port followed by a 30-degree 5-mm scope. Other surgeons recommend use of optical trocars in this situation.

Fascial Closure

Care should be taken to prevent port-site hernias, which occur in 0.65–2.80% of laparoscopic gastrointestinal operations,29 because they can lead to bowel obstruction, incarceration, and/or Richter's hernias. All defects created with a 10-mm or greater bladed trocar should be closed, although this is not necessary when using some of the newer nonbladed trocars that create smaller fascial defects.30,31 Most 5-mm defects do not require fascial closure in adults, although there are reported cases of hernias at these sites.9,32,33 Because there is always a possibility of formation of a port-site hernia, the smallest possible port always should be used. When a port is manipulated excessively or has to be replaced multiple times, there may be a larger than expected fascial defect that may require closure. Additional recommendations are to place ports lateral to the rectus muscles when possible.34 At the conclusion of the procedure, removal of ports from the abdomen should be observed to be certain that omentum or abdominal contents are not brought up through the abdominal wall.

Fascial closure can prevent trocar-site hernia.35 A number of port-site closure devices have been developed36 because small laparoscopic incisions make it difficult to close the abdominal wall with round needles. The closure devices function like crochet needles, passing a suture through the abdominal wall on one side of the fascial incision. The suture end is released intra-abdominally under laparoscopic visualization, and the needle is removed. The needle is replaced (without suture) on the other side of the incision, and the free end is secured and pulled back out through the abdominal wall. A knot is then tied that closes the trocar site, as viewed laparoscopically (Fig. 4-5).

Trocar Injury

The overall risk of a trocar injury to intra-abdominal structures is estimated to be between 5 in 10,000 and 3 in 1,000.14 Almost all injuries occur during primary trocar insertion. According to Chandler and colleagues,13 the most commonly injured organ is the small bowel (25.4%), followed by the iliac artery (18.5%), colon (12.2%), iliac vein (8.9%), mesenteric vessels (7.3%), and aorta (6.4%). All other organs were injured less than 5% of the time. The mortality from trocar injury is 13%, with 44% owing to major vessel injury, 26% to bowel injury with delayed diagnosis, and 20% to small bowel injury. Major vascular injuries are noticed immediately and require rapid conversion to laparotomy. They are managed by applying pressure when possible to allow the anesthesia team to maintain and correct volume and prepare for rapid blood loss. Then the surgeon gets control of inflow and outflow to permit repair of the injury. Unfortunately, many bowel injuries are not recognized at the time of the procedure, and nearly half are not noticed until more than 24 hours postoperatively. This obviously leads to severe sequelae and may be prevented by careful dissection and inspection at the conclusion of the procedure.

Telescope

Laparoscopic and thoracoscopic telescopes come in a variety of shapes and sizes, offering several different angles of view. The standard laparoscope consists of a metal shaft 24 cm in length containing a series of quartz-rod lenses that carry the image through the length of the scope to the eyepiece. The telescope also contains parallel optical fibers that transmit light into the abdomen from the light source via a cable attached to the side of the telescope. Telescopes offer either a straight-on view with the 0 degree or can be angled at 25–30 or 45–50 degrees. The 30-degree telescope provides a total field of view of 152 degrees compared with the 0-degree telescope, which only provides a field of view of 76 degrees (Fig. 4-6).

The most commonly used telescope has a diameter of 10 mm and provides the greatest light and visual acuity. The next most commonly used telescope is the 5-mm laparoscope, which can be placed through one of the working ports for an alternative view. Smaller-diameter laparoscopes, down to a 1.1-mm scope, are available and are used mostly in children. They are not used commonly in adult patients because of an inability to direct enough light into the larger abdominal cavity. The camera is attached to the eyepiece of the laparoscope for processing.

Video Camera

A high-resolution video camera is attached to the eyepiece of the telescope and acquires the image for projection on the monitor. The video image is transmitted via a cable to a video unit, where it is processed into either an analog or a digital form. Analog is an electrical signal with a continuously varying wave or shift of intensity or frequency of voltage. Digital is a data signal with information represented by ones and zeros and is interpreted by a computer. These are the methods by which the picture is transmitted to the video monitor. The camera and cable are designed so that they can be sterilized in glutaraldehyde.

The camera iris directly controls the amount of light processed by opening the aperture of the camera. The gain controls the brightness of the image under conditions of low light by recruiting pixels to increase signal strength. Clearly, this step results in some loss of image resolution. This increases light but results in a grainy picture with poorer resolution. It also may create a loss of color accuracy owing to amplification of the noise-to-signal ratio.

Light Sources

High-intensity light is created with bulbs of mercury, halogen vapor, or xenon. The bulbs are available in different wattages—150 and 300 W—and should be chosen based on the type of procedure being performed. Because light is absorbed by blood, any procedure in which bleeding is encountered may require more light. We use the stronger light sources for all advanced laparoscopy. Availability of light is a challenge in many bariatric procedures where the abdominal cavity is large. The light is carried to the fiberoptic bundles of the laparoscope via a fiberoptic cable. The current systems create even brightness across the field.

Insufflators

An insufflator delivers gas from a high-pressure cylinder to the patient at a high rate with low and accurately controlled pressure. Some insufflators have an internal filter that prevents contamination of the insufflator with the gas from the patient's abdomen and similarly filters any particulate matter that may be freed from the inside of an aging gas cylinder. Others require use with disposable insufflator tubing that has a filter on it. Some insufflators provide heated or humidified gas, but clinical benefit to these theoretically desirable features has not yet to be proven.

Video Monitors

High-resolution video monitors are used to display the image. Optimal monitor size varies but ranges from 19 to 21 in. Smaller monitors may be used if placed close to the operative field. Larger monitors provide little advantage outside of a display setting. Cathode-ray monitors (analog) are being replaced rapidly by flat-panel (digital) displays with excellent color and spatial resolution. These monitors may be positioned optimally when hung from the ceiling on light booms.

The instruments used in laparoscopic surgery are similar to those of open surgery at the tips but are different in that they are attached to a long rod that can be placed through laparoscopic ports. Standard-length instruments possess a 30-cm-long shaft, but longer instruments (up to 45 cm in length) have been developed for bariatric surgery. The handles come in many varieties and must be chosen based on comfort and ergonomics, as well as the need for a locking or nonlocking mechanism. The shaft of most hand instruments is 5-mm wide; however, some specialized dissectors are available only in a 10-mm width. Pediatric laparoscopy instrumentation is generally 2–3 mm in diameter (Fig. 4-7). Bowel graspers come in a wide variety with different types of teeth (Fig. 4-8). The most atraumatic grasper has small, smooth teeth like a Debakey forceps. This has the advantage of not tearing the tissues and can be used on almost all organs. We use the Hunter grasper (Jarit), which, like a Debakey, can be used to grasp bowel and also can be used to grasp a needle. An additional benefit is that the tip is blunt and not prone to causing tissue trauma. Another commonly used bowel grasper is the Glassman (Storz), which is atraumatic and is slightly longer than the standard-sized Hunter grasper. It is fenestrated and cannot be used to grasp a needle. For some tissues, these instruments do not “grip” well enough, and bigger teeth or a different tip, such as those of Allis and Babcock clamps, is preferred. We reserve these larger-toothed instruments only for organs that are being removed, such as the gallbladder, or for thicker tissue, such as the stomach. The rule is to be gentle because small injuries can take a relatively long time to fix laparoscopically.

The most commonly used dissector is the Maryland dissector (Fig. 44-9). It is useful for dissecting small ductal structures such as the cystic duct and can be used when dissecting vessels. Another use for the Maryland dissector is that it can be attached to monopolar cautery and used to grasp and cauterize a bleeding vessel (this should not be done with bowel graspers). The Maryland dissector should not be used to grasp delicate tissue because too much pressure is applied over a very small area, much like erroneously using a Kelly clamp for grasping tissue. Very delicate right-angle dissectors can be used for renal, adrenal, and splenic vessels and are less traumatic than the Maryland dissector because there are no ridges.

Hemostasis

Hemostasis can be achieved using current from a monopolar electrosurgical generator applied to common instruments and controlled with a foot pedal. One of the most useful instruments for dissection is a disposable hook attached to the hand-held Bovie device for dissection (Valley Labs/Conmed and others). If a vessel has been transected and is bleeding but is too large to control with monopolar electrosurgery, a pretied lassolike suture (Endo-loop, Ethicon Endosurgery) can be helpful. Laparoscopic clips are handy for small identifiable vessels but should not be used when a vessel is not identified. The clip is only 7 mm in length and is not useful for vessels larger than this. When the vessel is not clearly identified but the bleeding site is, ultrasonic shears and some bipolar instruments such as the LigaSure device (Covidien, Mansfield, MA) can be helpful. These instruments have the advantage of facilitating dissection while providing hemostasis for larger bleeding vessels.

Monopolar Electrosurgery

Although hemostasis is obtained using the same electrosurgical generator that is used in open surgery, there are hazards that are unique to minimally invasive surgery. The most frequently used method of delivering electrosurgery is monopolar. The desired surgical effect is hemostasis, and this is obtained by production of heat. Alternating current at 50,000 Hz (household current is 60 Hz) is generated and travels through an active electrode. The active electrode can be a Bovie tip in open surgery or, in laparoscopy, an instrument that is connected to the generator by the monopolar cord. The current passes into the target tissue at sufficiently high current density to cause a great deal of heat. Depending on tissue heating, coagulation, fulguration, or vaporization of the tissue occurs. The circuit is completed by the return of the electrons broadly spread through the tissue (insufficiently dense to cause any adverse effect) back to the generator via the return electrode (grounding pad).

In open surgery, monopolar current sometimes is passed from the active electrode (Bovie tip) to the patient via another conductive instrument, the forceps. This is called direct coupling. In laparoscopy, it is not prudent to touch the active electrode (an activated instrument) on or near other conductive instruments within the abdominal cavity, that is, the laparoscope or other working instruments. Direct coupling in minimally invasive surgery always should be avoided because injury may occur out of the surgeon's field of view. It is also not prudent to activate the generator in “midair” because the current may travel out of the surgeon's field of view to a crack in the insulation of a laparoscopic instrument. This results in transfer of current to a small area that generates heat and can produce an injury. All laparoscopic instruments should be checked for cracks in the insulation before being used.

Ultrasonic Shears

Before the introduction of ultrasonic shears, larger vessels had to be tied off individually. This was very tedious laparoscopically, especially with the division of short gastric vessels during fundoplication. The development of the ultrasonic shears was revolutionary, allowing surgeons to divide larger vessels quickly and dissect simultaneously. Ultrasonic energy or sound waves are used to ablate, cauterize, and cut tissues. A generator produces a 55.5-kHz (55,500 Hz) electrical signal that travels via a cable to a piezoelectric crystal stack mounted in the transducer. The crystal stack converts the electrical signal to mechanical vibration at the same frequency. The ultrasonic vibration is amplified as it traverses the length of the titanium probe that is the active blade of the scalpel. Shearing forces separate tissue and heat the surrounding tissue, thereby coagulating and sealing blood vessels without burning. Damage to adjacent tissues is low, although the active blade can become quite hot, and burn injuries can occur.

Bipolar Electrosurgery

Bipolar electrosurgery coagulates tissue by passing a high-frequency, low-voltage electric current between two directly apposed electrodes. Laparoscopic general surgeons use it much less frequently because an additional maneuver must be made to divide the tissue. The LigaSure, a newer bipolar device, coagulates larger vessels (up to 7 mm in diameter) and seals tissue and has a knife available for subsequent division of the tissue between the jaws of the forceps. The instrument makes a sound when the tissue within the jaw has been coagulated safely. The advantage is that division of larger vessels can be performed safely. Unfortunately, it is relatively slow to use as a dissecting instrument, and the tip is not very useful for dissection because it is straight and wide.37 It does not produce a large amount of heat, and damage to surrounding tissues is low.

Intracorporeal suturing may be out of the realm of the fundamentals of a laparoscopic surgery chapter. However, obtaining this skill is critical for successful performance of many laparoscopic procedures. A fundamental skill of laparoscopic surgery is the ability to place a suture accurately and tie a knot with a needle holder and a standard surgical suture. This skill can be mastered easily with a training box. Various suture aids have been developed, such as the EndoStitch (USSC), and can be used as a substitute. However, these devices are expensive, and the range of suture and needle sizes and types is limited. Many surgeons believe that an extracorporeal knot is acceptable because it is easier to create a knot outside the patient and slide it down with a knot pusher. In most settings, this is not true because securing an extracorporeal knot creates “sawing” of the tissue as the suture is pulled through or around it. This often results in tissue tearing. For interrupted suturing, the sliding square knot is the simplest most secure knot to master (Fig. 4-10).

The pneumoperitoneum has many effects that are only partially known despite years of study in humans and in animal models. There are effects resulting from the pressure within the abdomen and effects resulting from the composition of the gas used, generally CO2.

The pressure within the abdomen from pneumoperitoneum decreases venous return by collapsing the intra-abdominal veins, especially in volume-depleted patients. This decrease in venous return may lead to decreased cardiac output. To compensate, there is an elevation in the heart rate, which increases myocardial oxygen demand. High-risk cardiopulmonary patients cannot always meet the demand and may not tolerate a laparoscopic procedure.38 In volume-expanded healthy patients with full intra-abdominal capacitance vessels (veins), the increased intra-abdominal pressure actually may serve as a pump that increases right atrial filling pressure.39

Through a different mechanism associated with catecholamine release triggered by CO2 pneumoperitoneum, heart rate rises along with systemic vascular resistance. This may lead to hypertension and impair visceral blood flow. It is not uncommon after the induction of pneumoperitoneum for the heart rate to rise along with the mean arterial pressure. This leads to a minimal effect in a young, healthy patient40; however, in elderly, compromised patient, the strain on the heart can lead to hypotension, end-organ hypoperfusion, and ST-segment changes.

To minimize the cardiovascular effects of pneumoperitoneum, it is important that patients have adequate preoperative hydration. By insufflating the abdomen slowly, the vagal response to peritoneal stretching may be diminished and vagally mediated bradycardia avoided. Additionally, if cardiovascular effects are noted during insufflation or during the maintenance of pneumoperitoneum, the insufflation pressures should be lowered from the usual 15 to 12 mm Hg, or pneumoperitoneum should be evacuated while the anesthesiologist sorts out the cardiovascular changes. Taking patients out of the steep reverse Trendelenburg position can help to increase venous return. Sometimes these effects can last for hours after desufflation.

The elevated intra-abdominal pressures restrict movement of the diaphragm, which reduces diaphragmatic excursion. This is represented as a decrease in functional residual capacity and pulmonary compliance and an increase in inspiratory pressure. Overall, there is no significant change in the physiologic dead space or shunt in patients without cardiovascular compromise. Bardoczky and colleagues studied seven healthy patients undergoing laparoscopy with CO2 pneumoperitoneum.41 After the induction of pneumoperitoneum, peak airway and plateau airway pressures increased by 50% and 81%, respectively. Bronchopulmonary compliance decreased by 47% during the period of increased intra-abdominal pressure. After desufflation, peak and plateau pressures remained elevated by 36% and 27%, respectively, for 2–6 hours. Compliance remained at 86% of the preinsufflation value.

Urine output often is diminished during laparoscopic procedures and usually is the result of diminished renal blood flow owing to the cardiovascular effects of pneumoperitoneum and direct pressure on the renal veins.42 In addition to direct effects, elevated intra-abdominal pressure results in release of antidiuretic hormone (ADH) by the pituitary, resulting in oliguria that may last 30–60 minutes after the pneumoperitoneum is released. Aggressive fluid hydration during pneumoperitoneum increases urine output.43 Positional changes can affect the collection of urine in the Foley catheter and must be taken into consideration if anuria is noted.

Carbon Dioxide–Related Effects

Hypercapnia

Hypercapnia and acidosis are seen with pneumoperitoneum and are likely due to the absorption of CO2 from the peritoneal cavity. In the ventilated patient, increasing respiratory rate or vital capacity must compensate for these changes. At extremes, increases in tidal volume may risk barotraumas, and increases in respiratory rates diminish time for gas mixing, increasing dead-space ventilation. A first steady state in PaCO2 is reached around 15–30 minutes after introduction of the pneumoperitoneum. After this period, increases in PaCO2 suggest that existing body buffers (>90% exist in bone) have been exhausted. Sudden increases may be related to port slippage and extraperitoneal or subcutaneous diffusion of CO2. This will resolve spontaneously once the port is repositioned.

Hypercapnia and acidosis that are difficult to control may follow, especially in elderly patients, those undergoing long operations, and patients with pulmonary insufficiency. Our response to this is to desufflate the abdomen for 10–15 minutes. If reinsufflation results in recurrent hypercapnia, then we change insufflation gases (see above) or convert to an open operation. Acidosis can persist for hours after desufflation. Other complications of pneumoperitoneum that are less frequent but may be life threatening include CO2 embolism and capnothorax.

Carbon Dioxide Embolus

The incidence of clinically significant CO2 embolism is very low, although recent reports using more sensitive tests suggest that tiny bubbles of gas are present commonly in the right side of the heart during laparoscopic procedures. Clinically important CO2 embolism may be noted by unexplained hypotension and hypoxia during the operation. There is a characteristic millwheel murmur that can be detected with auscultation of the chest. This is produced by contraction of the right ventricle against the blood–gas interface. Usually the anesthesiologist notes an exponential decrease in the end-tidal CO2, which is consistent with complete right ventricular outflow obstruction. The mainstays of treatment are immediate evacuation of the pneumoperitoneum and placement of the patient in the left lateral decubitus, head down (Durant) position. This allows the CO2 bubble to “float” to the apex of the right ventricle, where it is less likely to cause right ventricular outflow tract obstruction. It is important to administer 100% oxygen and hyperventilate the patient during this period. Additionally, aspiration of gas through a central venous line may be performed.

Capnothorax/Pneumothorax

Capnothorax can be caused by CO2 escaping into the chest through a defect in the diaphragm or tracking through fascial planes during dissection of the esophageal hiatus. It also can be due to opening of pleuroperitoneal ducts most commonly seen on the right side. Pleural tears during fundoplication can lead to pneumothorax, and additionally, the usual causes of pneumotho rax, such as ruptured bullae, may be the etiology. The effects of CO2 gas in the chest usually are noted as decreased O2 saturation (a result of shunting induced by lung collapse), increased airway pressure, decreased pulmonary compliance, and increases in CO2 and end-tidal CO2. The treatment is to desufflate the abdomen, stop CO2 administration, correct the hypoxemia by adjusting the ventilator, apply positive end-expiratory pressure (PEEP), if possible, and decrease the intra-abdominal pressure as much as possible. The recommendation is to avoid thoracentesis because this usually resolves with anesthetic management. We generally evacuate the capnothorax directly at the end of the procedure with a red rubber catheter placed across the diaphragm (through the pleural defect) and brought out a trocar site. The external end of the catheter is placed under water as the lung is inflated and then removed from the water when the bubbles stop. We do not obtain chest radiographs in the recovery room after these maneuvers if there is no evidence of hypoxia on 2 L/min of O2 flow. Patients should be maintained on supplemental oxygen to help facilitate absorption of the CO2 from the pleural space.

Although minimally invasive surgery is firmly established in modern surgery, its safe performance can be ensured only with mastery of the basics. Basic skills used in laparoscopy include evaluation of a patient based on a new set of considerations, safe use of devices for abdominal access and instrumentation, and mastery of complex manual skills and intraoperative assessment of novel physiologic parameters. Laparoscopic surgery will only be employed more in the future as technical innovations allow us to care for our patients in new and better ways.