Mechanism of Injury

Access Injury

Laparoscopic surgery always carries the risk of inadvertent injuries that usually occur during the "learning curve" of various procedures. The exceptions to this rule, and some of the most feared injuries facing the laparoscopic urologist are those to vascular structures or bowel. These injuries are fortunately infrequent. The best method of managing these injuries is avoiding them. This is best accomplished by a thorough understanding of the equipment utilized during laparoscopy, high-risk maneuvers, mechanisms of injury, and recognizing when injury is present. Overall estimates of vascular and bowel injuries in large series are predominately quoted from older gynecologic literature. Vascular injuries have been difficult to quantify but occur at least in 0.1% of the cases. Bowel injuries have been variously reported between 0.06% and 0.3% (46).

Mechanisms of injury vary, however, most occurring during blind access maneuvers with the pneumoperitoneum needle or first trocar placement. The takeoff of the right common iliac artery lies directly below the umbilicus. It is crucial to angle the pneu-moperitoneum needle 30° to 45° caudally and carefully control forward pressure to insure abdominal access yet avoided excessive forward penetration. The same approach holds for trocar insertions. Bowel injuries from needle or trocar insertions usually occur in the presence of adhesions. Access should be planned to stay as far away from previous surgical incisions as possible or utilize open techniques. A summary of major series and the data from Chandler et al. (47) is shown in Table 1.

The risk of an injury may be associated with the operative procedure as well as its complexity. As the type of surgery moves away from the linea alba, as so often occurs in urologic laparoscopy, the possible risk of injury to the abdominal wall itself may increase.

TABLE 1 ■ A Summary of Major Injuries by Study Type

Author (discipline)

Cases

Year

Bowel

Major

Smaller vessel

Liver vessel

Stomach

Urinary bladder

Uterus

Other

Total (% coincidence)

Procedure-based retrospective

Fahlenkamp (UROL)

2,4O7

1992-1998

-

-

-

-

-

-

-

-

6 (O.25)

Harkki-Siren (GYN)

1O2,812

199O-1996

29

6

5

0

O

3

O

8

51 (O.O5)

Hashizume (GEN)

15,422

1991-1995

11

1O

70

1

O

0

O

64

156 (1.O)

Hulka (GYN)

14,911

1995

36

14

368

0

O

0

O

O

418 (2.8)

Champault (GEN, GYN)

1O3,852

1988-1994

35

35

237

13

5

2

O

1O

337 (O.32)

Deziel (GEN)

77,6O4

1989-199O

1O4

36

35

14

5

1

2

O

197 (O.25)

Procedure-based prospective

Leonard (GYN)

1,O33

1992-1998

2

1

6

0

O

3

1

4

17 (1.6)

Jansen (GYN)

25,764

1994

21

9

38

0

3

3

O

9

83 (O.3)

Injury-based retrospective

Marret (GYN)

?

1994-1997

12

11

18

0

O

3

O

3

47 (NA)

Yuzpe (GYN)

?

1985-1987

77

85

0

0

8

37

65

272 (NA)

Chandler (GEN, GYN, UROL)

?

1989-1999

218

239

70

13

11

19

7

17

594 (NA)

Source: From Ref. 47.

TABLE2 ■ Review of the General Surgical Literature in 1999 for Cause of Injury

No. with

No. with

Procedure

No. of patients

trocar complications

reference to design

Hernia repair

38

1O (26.3%)

4 (10.5%)

(transabdominal)

Lap. Nissen

57

8 (14.O%)

1 (1.7%)

Lap. colon

15

1 (6.7%)

0

Total

11O

19 (17.3%)

5 (4.4%)

Source: From Ref. 28.

The Veress needle and laparoscopic trocar's design has been implicated as a potential source of laparoscopic access injury. Several interesting reports and literature reviews have focused upon this issue. Despite advances in trocar technology such as safety shields, the incidence of injury has not altered appreciably.

Many complex laparoscopic surgery reports are published but seem to ignore the potential for access injury. Leibl et al. (28) have reviewed the general surgical literature in 1999 and reported in Table 2.

The Veress needle and laparoscopic trocar's design has been implicated as a potential source of laparoscopic access injury. Several interesting reports and literature reviews have focused upon this issue. Despite advances in trocar technology such as safety shields, the incidence of injury has not altered appreciably.

In addition, the most common method of laparoscopic access remains the blind insertion of a Veress needle, followed by insufflation, and then a second blind trocar insertion. There now exist many types of devices for laparoscopic access. These include Veress needle, open trocars (Hasson-type), shielded pyramidal trocars, shielded blade trocars, conical trocars, radial expanding trocars, short-stroke knife optical trocars, and winged cone optical trocars. Chandler et al. (47) used three data sources to identify access injuries reported with all types of these devices: The Physician Insurers Association of America on U.S. laparoscopic injuries and a second Physician Insurers Association of America database from Europe, Australia, and Canada. The third database came from the United States Medical Device Reports to the Food and Drug Administration. Their study encompassed more than 280,000 laparoscopic procedures and is injury-based instead of procedure-based, thus providing little data on the true incidence or relative safety. The results by type of access device are summarized in Table 3 (47).

Basically all categories of contemporary access devices have been reported to cause some type of injury. In the Medical Device Reports reports, the Veress needle only accounted for 2% of reported injuries whereas the Physician Insurers Association of America noted them in 13% to 19% (which is probably closer to actual). From these databases, it is also known that injuries from secondary trocar insertion are rare. There were nine entry injuries from the Medical Device Reports data and nine from the Physician Insurers Association of America data. Five from the Medical Device Reports set were associated with shielded pyramidal trocars, three from shielded blade trocars, and one small bowel puncture with a radially expandable device. The severity of the injuries was also recorded from these data sets. More than half of the patients suffering an access injury (55% overall from all three cohorts) were scored using the National Association of

TABLE3 ■ Chandler's Results from Several Large Databases Regarding the Type of Trocar Used and the Subsequent Injury

Device

MDR (n)a

%

PIAA (U.S.)/foreign (n)a

%U.S./%foreign

Shielded pyramidal

187 (3)

77.2

12 (1)/1

9/1

Shielded blade

21 (2)

8.7

- /-

-/-

Optical

Short-stroke knife

6 (1)

2.5

2/-

2/-

Winged cone

10 (2)

4.1

-/-

-/-

Veress needle

5

2.1

18/21

13/19

Unspecified trocar

4

1.7

85/91

64/80

Radially expandable sheath

4 (4)

1.7

-/-

-/-

Open blunt (Hasson)

2

0.8

16/-

12/-

Multiple-use pyramidal

2

0.8

-/-

-/-

Conical

1

0.4

-/-

-/-

Total

242 (12) 100.0

133 (1)/113

100/100

an numbers in parentheses indicate that 12 of 235 (5%) devices other than the Veress needle or an open blunt cannula without prior insufflation.

Insurance Commissioners injury severity index indicating a major impairment or disability. In addition, there were 65 deaths from access injuries, all from primary access except one secondary trocar injury to the duodenum. Mortality was significantly lower in the two U.S. cohorts compared to the international group (11% vs. 22%, p = 0.0008). The international group had a more significant number of bowel injuries and a significantly greater proportion of patients presenting with a delay in diagnosis (60% international vs. 17% in the United States, p < 0.001) (47).

Lest the reader think that the open methods for laparoscopic access have no risk of injury, think again. Open techniques have been associated with serious potential risks of both major vascular and bowel injuries (48). The mechanisms for these injuries are nearly identical to the closed methods. That is the route of access is via a small incision down through the rectus fascia. The peritoneum is grasped and either opened with scissors or knife. This forward vector of force is all that is necessary in thin patients to injury a closely apposed vessel or bowel. Injuries have also been reported with this technique by placing holding fascial sutures that inadvertently catch underlying bowel. In addition, a Hasson cannula has been reported to injure the small bowel by constant pressure applied "off camera" during a prolonged laparoscopic surgery.

Pneumoperitoneum Injury

The complications of pneumoperitoneum are presented in Table 3. Certainly, not all patients experience detrimental complications associated with CO2 insufflation, otherwise there would be no widespread interest in this approach to treating uropathology. Most of the consequences mentioned above are transient and the operative procedure can continue with continuous monitoring of the patient. Overall, Parsons et al. (49) has estimated that during urologic laparoscopic procedures that insufflation problems occur in about 3.5% of the cases.

Instrument Injuries

Instruments can cause unintended injury as well as the trocars used for laparoscopic access. Most of these injuries affect the bowel most commonly with lacerations, injury to the mesentery with bleeding being the most frequent. Since these types of injury are most prevalent during the operative dissection, they are frequently observed (50).

The most common type of nonobserved instrument injury comes from retraction. These can be punctures, lacerations, or hematomas from overzealous traction during exposure (51). Retraction instruments should always be positioned with video control, and any repositioning should be observed and monitored.

Following prolonged retraction with such devices, the retracted organ or area should always be thoroughly inspected. Small lacerations of the bowel's serosa can be oversown. Deeper lacerations or frank perforations should be individualized, but classic teaching would suggest open conversion and close inspection of the injury and debridement and closure. There has been successful laparoscopic management of bowel lacerations reported in the literature. Such patients should be managed with bowel rest, nasogastric suction, and antibiotics. Injuries have also been reported during both

The most common type of nonobserved instrument injury comes from retraction. These can be punctures, lacerations, or hematomas from overzealous traction during exposure. Retraction instruments should always be positioned with video control, and any repositioning should be observed and monitored.

Electrocautery injuries are often not noticed and can be quite severe, resulting in delayed presentation of peritonitis secondary to fecal contamination or urinary extravasation 7 to 10 days following the surgical procedure. Patients often present with very minimal symptoms but rapidly decompensate and, in many instances, may require more than one surgical intervention for repair.

laparoscopic renal and adrenal surgery to the liver and spleen (52). If the injuries are superficial, attempts to control the injury laparoscopically with gel foam, avitene, or with an argon beam coagulator have been reported. Open exploration for these injuries has likewise been described.

Electrocautery Injury

The explosion of laparoscopic procedures both in general surgery and urology has lead to rekindled interest in the risks of monopolar electrocautery, the use of alternative energy sources such as bipolar cautery, lasers, argon beam coagulation, and ultrasound activated devices (harmonic scalpel). These energy sources are predominately utilized for bloodless dissection and control of vascular structures, critical for the performance of laparoscopic surgery. In the survey of the American College of Surgeons, 86% of all surgical laparo-scopists were using monopolar cautery. In a more recent survey in Germany, about 84% of all surgeons used monopolar cautery routinely in all laparoscopic cases. In an open surgical environment, monopolar electrocautery is relatively safe, with the major significant risk being skin burns (53). In the laparoscopic environment, however, potential complications are far more serious with mortality rates approaching 25% or more for inadvertent injuries to small and large bowel. The need for thorough review of the potential implications will greatly aid in the development of safe laparoscopic procedures for urologists in this burgeoning field. One should not forget the admonitions of experienced gynecologic surgeons from the 1970s and 1980s where routine editorial comments on the potential for harm with the indiscriminant use of monopolar electrocautery were published (54-56).

In review of the large volume of literature on high-frequency electrosurgery in laparoscopic environment, seven possibilities exist for a laparoscopic electrocautery injury (57). Thorough understanding of these mechanisms of potential laparoscopic injury will help facilitate the safe advancement of skills in laparoscopic surgery. The first potential modality of electrocautery injury laparoscopically is the application of an active electrode to nontargeted tissue. This occurs when an electrically charged instrument is inadvertently activated such as stepping on the foot petal at the wrong time or touching another conductive instrument with cautery activated. Since the surgical field of view tends to be rigidly controlled to the point of surgical dissection, these injuries are usually noticed by the surgeon at the time of injury. The second possibility for elec-trocautery injury occurs when a restricted return pathway is encouraged. This happens when over cautery is achieved at the tip of the active electrode, increasing tissue impe-dence and alternative return pathways must be sought by the active electrode. Here, for instance, when dividing adhesion to a visceral structure, if the peritoneal side is stringently cauterized the pathway may return by way of the bowel and cause inadvertent bowel injury. These two are often in the direct line of sight during operative procedures and careful avoidance of utilizing too much monopolar electrocautery where tissue charring occurs should be avoided. The third mechanism of potential electrocautery injury occurs when overheating of the active electrode is present. Here, again, if the tips of electrocautery instrument become charred or stuck with tissues, heat dissipation by free flow of the electrical current is impaired and the tips of the active electrode become quite hot. By simply touching an adjoining visceral structure with the hot electrode thermal damage can ensue. This typed of injury has been reported in the urologic literature, where the obturator nerve was injured during laparoscopic lymph node dissection with what appeared to evolve as a conductive thermal burn, but progressed even after the first week postoperatively. The next four other methods of possible electrocautery injury in a laparoscopic environment have a tendency to occur outside of the surgeon's line of sight and, therefore, have much greater potential for patient morbidity and mortality. The fourth type of injury occurs when conductive instruments are energized inadvertently. The classic example of this would be where the surgical instruments are all converging toward the targeted area of dissection, the electrode is activated and the instrument is too close to another such as the laparoscope itself, which then conducts the current in a stray fashion to a structure outside the line of sight.

Electrocautery injuries are often not noticed and can be quite severe, resulting in delayed presentation of peritonitis secondary to fecal contamination or urinary extravasation 7 to 10 days following the surgical procedure. Patients often present with very minimal symptoms but rapidly decompensate and, in many instances, may require more than one surgical intervention for repair.

The fifth potential method of inadvertent electrocautery injury occurs when insulation failures occur on the active electrode within a trocar cannula. There are two subcategories where the type of injury depends on the type of trocar used and whether or not a plastic fascial screw is present in the abdominal wall. Obviously, when an

These types of injuries are best avoided by simple inspection of the instruments and routine maintenance of the instruments. All insulation can eventually wear down and insulation failures are a real clinical dilemma.

insulation failure occurs within the trocar, the trocar will become electrified if it is a conductive medium. Even in instances where the trocar is not conductive, such as with plastic cannulas, failures in these can result in inadvertent conduction to the abdominal wall. Studies with biopsy of the skin sites from laparoscopic cannula sites have proven that thermal necrosis occurs at trocar sites, both metallic and plastic. When a plastic fas-cial screw further insulated the trocar from the abdominal wall, an insulation failure within the trocar is potentially even more dangerous. The activated electrode can build up a capacitance charge and leaking from this can arc to a nearby visceral structure. These will often be missed since they are outside of the targeted area of laparoscopic surgery and can have the same devastating consequences of the previous electrocautery injuries described. The sixth mechanism of a laparoscopic electrocautery injury occurs when insulation failure occurs outside of the trocar on the active electrode. These insulation failures are often small and not noticed and the potential for current arcing to a nontargeted viscus is highly likely (58). If the surgeon is careful to inspect the tract of the pathway of the surgical procedure, these can be identified during the laparoscopic procedure. There have been reported cases of insulation failure injuries with electrothermal injury to the small and large bowel, corrected laparoscopically at the time of the primary procedure. Careful inspection of all active electrodes should occur outside of the abdomen prior to instigating the laparoscopic procedure.

These types of injuries are best avoided by simple inspection of the instruments and routine maintenance of the instruments. All insulation can eventually wear down and insulation failures are a real clinical dilemma.

Disposable instruments are less likely to have insulation failure since they are one time use and are discarded at the conclusion of each case. If, however, during the course of a complex laparoscopic procedure, the same instrument is passed multiple times through a trocar, the insulation can get worn down through the process of insertion and reinsertion. The seventh and final modality wherein inadvertent laparoscopic electro-cautery injuries occur are secondary to capacitive leakage of current from the active electrode. This probably occurs in a laparoscopic environment more than previously thought. As the electrode is activated, the charge builds up and moves through the conductive electrode. If at any point the flow is interrupted by restricting the return pathway or any point wherein the active electrode becomes close enough to another conductor, current can leak from the active electrode to another return site pathway by discharging this built-up current. Since this can occur at any location along the insertion site of the active electrode, many times it will occur outside of a surgeon's operative view and again poses a major potential risk for subsequent electrothermal injury.

There are entire textbooks, meetings, and courses on the rational use of electro-cautery in laparoscopic surgery. Methods exists however to minimize these risks. First, always know your laparoscopic electrosurgical generator (59). The patient should be well grounded, with a broad return pathway (pad) in correct orientation. The electro-cautery instruments and any other instrument in the peritoneal cavity should be inspected to insure adequate insulation. When the cautery is activated, it should only be applied by the surgeon and no assistant movement should be allowed. There should be no use of forced coagulation, but recent investigations utilizing spray coagulation suggest it might have utility. The newer microprocessor-controlled electrocautery units should be preferred over the older units. One such instrument is called "Instant Response™"a (60). This is a self-regulating, feedback-controlled electrosurgical unit that allows tissue conditions to be fed back to the microproccesors within the electrical generator. These capabilities allow the generator to tailor the electrical output to local laparoscopic conditions. Cutting and coagulation performance are enhanced in these new age systems; this may allow safer performance of monopolar electrocautery in the future. In addition, the behavior of the insulation material on the outside of laparo-scopic instruments, usually plastic, is being evaluated. Alterations of this coating may improve the efficiency and alter the desired effects making tailored devices of the future possible. Bipolar systems have an advantage over monopolar electrocautery by confining the energy between the twines of the active electrode and return electrode at the instrument's tip. Complex microprocessing electrosurgical generators and improved instrument manufacturing have improved these devices significantly (61). Such a device was used by Guilloneau et al. to perform the first large series of laparoscopic radical prostatectomies in Paris. If alternative methods of cautery are available and the surgeon is comfortable with the technology, the harmonic scalpel accomplishes similar aValley Lab, Boulder, CO.

Major vascular injury as the cause of death following a laparoscopic surgery is second only to anesthesia complications, at 15%. Pneumoperitoneum needle injuries account for the vast majority of major vascular injuries reported.

An adequate response in a controlled yet rapid fashion can spare further morbid sequelae.

tasks to the electrocautery without an active current being utilized (62,63). Cutting and coagulation can be accomplished using either electromagnetic or mechanical energy, thus avoiding electrocautery completely. Electromagnetic energy sources rely on heat derived from either light (lasers) or radiofrequency waves (electrosurgery) to produce tissue cutting and coagulation (62). The tissue temperatures from these sources often reach 100°C or greater (64). Since collagen denaturation and protein coagulation occurs between 60°C and 80°C, tissue desiccation and charring ensue. Using mechanical energy, the ultrasonically activated devices (harmonic scalpel) rely on vibratory motion to generate heat from internal tissue friction to cut and coagulate. This method generates lower tissue temperatures from 80°C to 90°C, which is sufficient for coagulation but not for desiccation or charring. Using either a laser or an ultrasonically activated device totally avoids the risk of inadvertent electrocautery injury.

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