A comparative analysis of adhesion reduction, tissue effects, and incising characteristics of electrosurgery, CO2 laser, and Nd:YAG laser at operative laparoscopy: an animal study

An Overview of Postoperative Intraabdominal Adhesions and Their Role on Female Infertility: A Narrative Review

Postoperative intraabdominal adhesions can occur after more than 90% of gynecologic surgeries. They not only cause chronic pelvic pain and small bowel obstruction, but are also one of the main reasons for infertility. Adhesions are not only a burden for the affected patients, but are also a burden for the healthcare system, since the treatment of adhesion-associated complications costs a considerable amount of money. The gold standard for the diagnosis of adhesions is by laparoscopy, although other methods, such as transvaginal hydro-laparoscopy, are being discussed as better alternatives. Ideally, adhesions are avoided inherently, by operating carefully and by using microsurgical principles. If this is not possible, gel barriers have been shown to be successful in reducing postoperative adhesions.

Laser technology and applications in gynaecology

The term 'laser' is an acronym for Light Amplification by Stimulated Emission of Radiation. Lasers are commonly described by the emitted wavelength, which determines the colour of the light, as well as the active lasing medium. Currently, over 40 types of lasers have been developed with a wide range of both industrial and medical uses. Gas and solid-state lasers are frequently used in surgical applications, with CO2 and Ar being the most common examples of gas lasers, and the Nd:YAG and KTP:YAG being the most common examples of solid-state lasers. At present, it appears that the CO2, Nd:YAG, and KTP lasers provide alternative methods for achieving similar results, as opposed to superior results, when compared with traditional endoscopic techniques, such as cold-cutting monopolar and bipolar energy. This review focuses on the physics, tissue interaction, safety and applications of commonly used lasers in gynaecological surgery.

The influence of water/air cooling on collateral tissue damage using a diode laser with an innovative pulse design (micropulsed mode)-an in vitro study

Since the diode laser is a good compromise for the daily use in dental offices, finding usage in numerous dental indications (e.g., surgery, periodontics, and endodontics), the minimization of the collateral damage in laser surgery is important to improve the therapeutical outcome. The aim of this study was to investigate the effect of water/air cooling on the collateral thermal soft tissue damage of 980-nm diode laser incisions. A total of 36 mechanically executed laser cuts in pork liver were made with a 980-nm diode laser in micropulsed mode with three different settings of water/air cooling and examined by histological assessment to determine the area and size of carbonization, necrosis, and reversible tissue damage as well as incision depth and width. In our study, clearly the incision depth increased significantly under water/air cooling (270.9 versus 502.3 μm-test group 3) without significant changes of incision width. In test group 2, the total area of damage was significantly smaller than in the control group (in this group, the incision depth increases by 65 %). In test group 3, the total area of damage was significantly higher (incision depth increased by 85 %), but the bigger part of it represented a reversible tissue alteration leaving the amount of irreversible damage almost the same as in the control group. This first pilot study clearly shows that water/air cooling in vitro has an effect on collateral tissue damage. Further studies will have to verify, if the reduced collateral damage we have proved in this study can lead to accelerated wound healing. Reduction of collateral thermal damage after diode laser incisions is clinically relevant for promoted wound healing.

Effects on oral soft tissue produced by a diode laser in vitro

BACKGROUND AND OBJECTIVES

This investigation determined incision characteristics and soft-tissue damage resulting from standardized incisions using a wide range of laser modes and parameters of a diode laser at 810 nm.

STUDY DESIGN/MATERIALS AND METHODS

Histologic examinations were performed to verify vertical and horizontal tissue damage as well as incision depth and width.

RESULTS

Incision depth and width correlated strongly with average powers, but not with laser parameters or the used tips. No laser damage was visible to the naked eye in the bone underlying the incisions in the range between 0.5-4.5 W.

CONCLUSION

The remarkable cutting ability and the tolerable damage zone clearly show that the diode laser is a very effective and, because of its excellent coagulation ability, useful alternative in soft-tissue surgery of the oral cavity.

Electrosurgery in the head and neck

Electrosurgery is widely used in the practice of otolaryngology-head and neck surgery. Despite its popularity, few training programs give formal education in the optimal use of electrosurgical instruments. This article reviews the history, physics, and tissue effects of these commonly used devices. Armed with this knowledge, the head and neck surgeon can take full advantage of electrosurgery's ability to dissect tissues with precision and minimal blood loss.

The influence of laser parameter configurations at 9.3 microns on incisional and collateral effects in soft tissue

These investigations were performed to determine histologic and incisional consequences of varying pulse duration, duty cycle, and average powers during laser incision at 9.3 microns in soft tissue. In 19 fresh pigs' jaws six standardized incisions 3 cm long were made per parameter with a template and motorized jig. Laser parameters investigated were average power: 1 to 9 W, duty cycle: 10% to 80%, and pulse duration: 1 to 200 msec. The gated Cw mode was used. Incision width and depth and collateral tissue effects were assessed statistically with general linear procedures. Multiple factors were found to influence the outcome of laser irradiation. Depth of incision correlated positively with average power. Tissue damage correlated strongly and negatively with all three variables. These results demonstrate that a wide range of surgical and collateral effects can be achieved with one specific laser device depending on the parameter configuration selected.

Investigating the range of surgical effects on soft tissue produced by a carbon dioxide laser

The authors investigated the surgical and collateral effects on soft tissue of a carbon dioxide laser emitting at 9.3 micrometers. Specifically, incision widths and depths as well as effectiveness were studied. Three different laser modes were investigated: gated continuous wave, or Cw, Superpulse and OptiPulse (Medical Optics). Incision depths correlated positively with average power; higher powers produced deeper incisions. The gated Cw mode quickly produced wide, deep incisions; Superpulse achieved narrower, deep incisions; OptiPulse caused very narrow, shallow incisions. Collateral damage to adjacent tissues was reduced by a factor of about 2 using Superpulse, and by a factor of 10 using OptiPulse. A wide range of effects is achieved in soft tissue, depending on the laser parameter combination used.

Preliminary assessment of the tissue effects of a 1.44-micron laser via direct fiber contact on soft tissue

BACKGROUND/OBJECTIVE

A new pulsed near-infrared laser was developed for incision of soft tissues. This article presents a preliminary investigation of the 1.44-micron laser.

METHODS

A prototype laser was used with a cleaved 600-micron quartz fiber (1.44 microns, 5-30 Hz, 30 W max.). Standardized 5-cm incisions were made on skin, striated muscle, and liver in anesthetized New Zealand White rabbits. The animals were euthanized and the tissues were immediately harvested, and histologic examination completed after hematoxylin and eosin (HE) staining. The acute zone of coagulation was measured. A wound healing study was conducted on anesthetized NZW rabbits. The hind leg muscle was exposed and four, 5-cm incisions were made using the laser (0.5 J, 25 Hz) and four incisions were made with an electrosurgical unit on coagulating current (25 W). The incisions were marked and the overlying skin reapproximated. One rabbit was euthanized on day 11 and one on day 21. The wounds were exposed and excised for histology.

RESULTS

The acute zone of injury was 1160 +/- 120 microns to 1250 +/- 110 microns for skin; 70 +/- 20 microns to 400 +/- 280 microns for muscle, and 660 +/- 120 microns to 1930 +/- 300 microns for liver. The chronic study demonstrated less inflammation in the laser wounds on day 11 and a chronic inflammatory response on day 21. No gross differences in healing were noted.

DISCUSSION/CONCLUSION

The 1.44 microns laser wavelength interacts with tissues in a manner that is substantially equivalent to the holmium laser (2.1 microns). Further studies of the 1.44 microns laser and delivery system development are warranted.

Use of medroxyprogesterone acetate in the prevention of postoperative adhesions

OBJECTIVES

To evaluate the efficacy of a commonly used progestogen, medroxyprogesterone acetate (MPA), in the prevention of postoperative adhesion formation.

DESIGN

A double-blind, controlled study evaluated the efficacy of MPA to reduce postoperative adhesion formation and compared it with other adjuvants and controls in a rat model.

SETTING

Animal Care Facility of an academic research setting.

SUBJECTS

Seventy-five Sprague-Dawley female rats randomly divided into five groups.

INTERVENTIONS

Three weeks before surgery, the animals from each group were administered an IM injection of one of the following regimens: [1] 15 mg MPA; [2] both 15 mg MPA and 0.75 mg leuprolide acetate (LA); [3] 0.75 LA; or [4] and [5] comparable volumes of sterile saline. A standardized surgical trauma was inflicted in all animals. Before abdominal closure, 2 mL of Ringer's Lactate was instilled in the abdominal cavity of all groups except group 5 (controls). Three weeks after surgery, the rats were killed and the adhesions were scored on a scale of 0 to 3 according to their size, thickness, and vascularity.

MAIN OUTCOME MEASURE

Postoperative adhesions.

RESULTS

The preoperative administration of MPA resulted in the least number and the least severe adhesions. The combination of LA and MPA did not reduce postoperative adhesion formation. Both Ringer's Lactate and LA reduced postoperative adhesions but not to the same extent as MPA.

CONCLUSION

The preoperative administration of MPA in our laboratory animal model results in the most significant reduction of postoperative adhesion formation. This action of MPA may be mediated by the induction of both a progestational and a hypoestrogenemic milieu. However, the ultimate role of MPA in a clinical situation requires further investigation.

Incision properties and thermal effects of three CO2 lasers in soft tissue

OBJECTIVES

It was the aim of this study to determine thermal and histologic events resulting from soft tissue incision with three CO2 lasers: one emitting light energy via a hollow waveguide at 9.3 microns; the others emitting light energy at 10.6 microns, one via a hollow waveguide, the other through an articulated arm delivery system.

STUDY DESIGN

Thirty standardized incisions were made in the oral mucosa of pig's mandibles with three different lasers at actual power levels of 1, 4 and 12 W. Thermal events were recorded with thermocouples, and a histologic examination was performed to determine vertical and horizontal tissue damage as well as incision depth and width.

RESULTS

Thermal and histologic results were related to parameters and beam characteristics rather than wavelength.

CONCLUSION

In addition to wavelength, many variables can contribute to the surgical characteristics of a laser.

Loop electrosurgical excision with a laparoscopic electrode and carbon dioxide laser vaporization: comparison of thermal injury characteristics in the rat uterine horn

OBJECTIVE

Our purpose was to compare the thermal intraperitoneal injury in lesions resulting from a monopolar electrosurgical loop electrode designed for laparoscopic surgery with similar lesions fashioned by carbon dioxide laser vaporization.

STUDY DESIGN

A randomized, observer-blinded comparison was made of histopathologically measured thermal injury in rat uterine horns. The primary outcome measure was the depth of necrotic debris and coagulative necrosis in the lesions created by the two methods.

RESULTS

The depth of coagulative necrosis was similar in the laser vaporization (0.118 +/- 0.028 mm) and the loop excision groups (0.165 +/- 0.167 mm). However, the average amount of necrotic debris was greater in the lasered lesions (0.053 +/- 0.019 mm) compared with those made with the loop electrode (0.013 +/- 0.011 mm).

CONCLUSIONS

The depth of coagulative necrosis in rat uterine lesions fashioned with a loop electrode is similar to that of lesions created by carbon dioxide vaporization at power densities comparable with those usually achieved at laparoscopic surgery. There is a greater amount of necrotic debris in the lasered lesions. This suggests that electrosurgical loops designed for laparoscopic surgery may have promise for the cost-effective excision of intraperitoneal tissue.