Quantitation of colonic injury from argon laser, neodymium: YAG laser and monopolar electrocautery applied to flat mucosa and small sessile polyps of the canine colon

A blinded comparison of the safety and efficacy of hot biopsy forceps electrocauterization and conventional snare polypectomy for diminutive colonic polypectomy in a porcine model

BACKGROUND

Although linked with perforation, serositis, delayed bleeding, and incomplete resection, hot biopsy forceps electrocauterization (HBF) is still widely used for diminutive colonic polypectomy.

OBJECTIVE

To evaluate the safety and efficacy of HBF in comparison with conventional snare polypectomy (CSP).

DESIGN

Randomized, blinded, controlled trial.

SETTING

Academic endoscopy unit.

SUBJECTS

Ten swine.

INTERVENTION

Eighty-two paired polypectomies (41 HBF, 41 CSP) of small, minimally elevated, artificial lesions. Standardized technique using coagulating current at 25 W. HBF: the tissue was avulsed after 1 to 2 seconds of current caused blanching of the artificial pedicle. CSP: the polyp was removed by snare diathermy.

MAIN OUTCOME MEASUREMENTS

Histopathology of resected specimens and polypectomy sites in colectomy specimens at necropsy (lateral mucosal and depth of ulceration, necrosis and inflammation).

RESULTS

Some (21%) of the HBF specimens were ablated and uninterpretable. All CSP specimens yielded interpretable specimens. Mucosal necrosis adjacent to HBF resection sites varied widely, between 1.5 and 9 mm (mean 5.7 mm, standard deviation ± 2). There was visible mucosa under the HBF ulcer in 14% of cases. The depth of necrosis in the colon wall was significantly different between the two techniques, with partial muscularis propria (MP) necrosis in 14 of 41 lesions (34%) with HBF, compared with 1 of 41 (2%) of CSP (P < .001), and full-thickness MP necrosis in 9 of 41 lesions (22%) with HBF, compared with 1 of 41 (2%) of CSP (P = .014). There was full-thickness MP inflammation in 13 of 41 lesions (32%) with HBF compared with 5 of 41 (12%) of CSP (P = .06). Transmural subserosal inflammation was seen in 13 of 41 lesions (32%) with HBF compared with 4 of 41 (10%) of CSP (P = .027). There was no relationship between visible lateral mucosal injury and depth of injury (rs = -0.07).

LIMITATIONS

Animal study.

CONCLUSION

Despite use of the standardized HBF technique, there is a wide range of lateral mucosal and deep thermal injury as well as residual target mucosa. HBF also results in a significantly greater depth of tissue injury, with a high proportion of transmural necrosis. Ensuring minimal blanching of the mucosa during the procedure does not protect from deep injury. In comparison to conventional snare polypectomy, HBF is imprecise, potentially ineffective, and hazardous.

In vivo characterization of colonic thermal injury caused by argon plasma coagulation

BACKGROUND

Argon plasma coagulation has been rapidly accepted for endoscopic obliteration of vascular lesions and superficial tumors. Depth of injury is thought to be limited through preferential discharge of energy to nondesiccated tissue. However, argon plasma coagulation-induced injury has not been well characterized. The aim of this study was to characterize argon plasma coagulation-induced colonic injury by using a porcine model.

METHODS

Laparotomy was performed in 6 female swine and the colon exteriorized with the subjects under general anesthesia. Lesions were made with an argon plasma coagulation probe held perpendicular and 2 mm from the mucosa. Variables studied were as follows: power (45 W, 60 W, and 75 W) and duration (1, 2, or 3 seconds; n = 11 for each power/duration combination). Injury was graded as either superficial or deep, involving the muscularis propria.

RESULTS

Circular muscle layer injury correlated closely with power (p = 0.02), duration (p = 0.001), and total energy delivered (r = 0.977). Longitudinal muscle damage was associated with duration of burn (p = 0.001) and total energy delivered (r = 0.855), but correlated poorly with power (p = 0.40). No perforations occurred. Submucosal injection of saline solution had a protective effect with reductions in circular (90% to 10%, p = 0.002) and longitudinal muscle injury (50% to 0%, p = 0.1).

CONCLUSIONS

Injury to the muscularis propria occurs at recommended settings for argon plasma coagulation. Injury correlates with power setting, duration of burn, and total energy delivery. Protective arcing to nondesiccated tissue does not appear to be significant in vivo. Submucosal injection of saline solution protects against deep injury.

Treatment with argon plasma coagulation reduces recurrence after piecemeal resection of large sessile colonic polyps: a randomized trial and recommendations

BACKGROUND

Recurrence is frequent after piecemeal snare resection of large sessile colorectal polyps. The aim of this study was to evaluate the safety and efficacy of argon plasma coagulation (APC) in preventing recurrence when applied to the edge and base of the polypectomy site after apparently complete piecemeal resection.

METHODS

Patients with large (>1.5 cm) sessile polyps removed by piecemeal snare cautery were placed into 2 groups. The first consisted of patients with polyps believed by the endoscopist to be completely excised. These patients were randomized to either no further therapy (control) or to APC of the rim and any residual mucosal or submucosal tissue in the base of the polypectomy site. The second group comprised patients in whom polyps, as judged by the endoscopist, were incompletely excised by snare polypectomy; APC was routinely applied without randomization to all visible remaining adenomatous tissue. Follow-up colonoscopy was performed within 3 months and 1 year; biopsy specimens were taken routinely from the resection site and further polypectomy was performed as indicated.

RESULTS

There were fewer recurrences after APC in the randomized group (1/10 APC, 7/11 no APC; p = 0.02). In the group with initial incomplete snare polypectomy, recurrence was detected at 3 months in 6 of 13 despite APC. One patient was hospitalized with abdominal pain and minor rectal bleeding but required no intervention. There were no other episodes of significant late bleeding caused by piecemeal polypectomy. One patient was referred for surgery after unsuccessful endoscopic management.

CONCLUSIONS

In patients with apparent complete endoscopic snare resection of large adenomas, postpolypectomy application of APC reduces adenomatous recurrence.

KTP laser therapy for bleeding from chronic radiation proctopathy

BACKGROUND

Endoscopic laser photocoagulation is commonly used to treat bleeding from the neovascular lesions of chronic radiation proctopathy. The KTP laser is an Nd/YAG-driven unit that emits light with a wavelength of 532 nm. This wavelength of energy is absorbed by hemoglobin and penetrates tissue to a depth of only 1 to 2 mm.

METHODS

Twenty-three patients were treated with KTP laser and followed for a median of 29 months (range 5 to 51 months); 21 had received radiation for prostate cancer and 2 for uterine cancer. The median age was 77 years (range 68 to 87 years). A median of 2 sessions (range 1 to 5 sessions) was performed using 4 to 10 Watts of power and a median energy of 816 Joules per session (range 204 to 2430 Joules).

RESULTS

After treatment there was a significant reduction in the frequency (p = 0.0005) of bleeding, increase in hematocrit level (p < 0.0001), improvement in activities of daily life (p = 0.01), and a reduction in use of health care resources (p < 0.0001). There was a trend toward decreased use of iron supplements (11 to 4 patients) and transfusions (4 to 0 patients). Two patients (9%) developed rectal ulcers after treatment.

CONCLUSIONS

KTP laser photocoagulation is a safe and effective therapy for bleeding from chronic radiation proctopathy that improves activities of daily living and reduces use of health care resources.

Iatrogenic and accidental colon injuries--what to do?

PURPOSE

This study was designed to formulate management guidelines for a variety of rare iatrogenic and accidental injuries to the colon and rectum.

METHODS

This review collates the available evidence in the literature.

RESULTS

Both investigative and therapeutic maneuvers involving the colon, particularly endoscopy and radiographic contrast studies, are the most common cause of significant injury although the incidence is low. Even less common are injuries produced, at open surgery and minimally invasive surgery, by foreign bodies, enemas, or compressed air. The mechanisms and management of these injuries are discussed in detail.

CONCLUSIONS

Evidence exists to support that a nonoperative approach is safe for the majority of injuries, particularly when the colon is "clean" at the time of injury. Adequate resuscitation, observation, and repeated reassessment are mainstays of a conservative policy. Operation is essential for progression of abdominal signs. Patients with established peritonitis at the time of presentation or with an unprepared bowel are best served by prompt operation.

Laser therapy of gastrointestinal tumors

Surgical resection remains the therapy of choice for the treatment of potentially curable gastrointestinal tract (GI) malignancies. Many of these tumors are incurable at the time of diagnosis and therapy should be directed towards palliation with the intent of minimizing pain, bleeding, obstruction, and potential morbidity. Endoscopic laser therapy is uniquely applicable for the palliation of GI tumors and in selective instances may be appropriate for the treatment of early lesions. Eighty-six patients with GI malignancy have been treated at our institution since 1985. Thirty-one patients had advanced upper GI lesions (esophagus: 26, gastric: 3, duodenal: 1, and pancreatic: 1) and 55 patients had lower GI tumors (colon: 37 and rectal: 18). Pre-resectional recanalization for obstructing colorectal carcinomas obviating initial operative diversion was performed in 31 (56%) of 55 patients. Twenty-four patients had palliative laser therapy (obstruction: 17 and hemorrhage: 7) with resolution of their symptoms. There was 1 laser related perforation in the pre-resectional group and the overall complication rate was 1.2%. Endoscopic Nd:YAG and currently photodynamic laser therapy for GI tumors has proven to be an effective mode of therapy for advanced GI neoplasms with minimal morbidity. The utility of photodynamic therapy for the treatment of early stage esophageal and gastric cancers remains controversial.

Status evaluation: hot biopsy forceps. American Society for Gastrointestinal Endoscopy. Technology Assessment Committee

Monopolar hot biopsy forceps were developed for simultaneous tissue biopsy and electrocoagulation. Many endoscopists used these forceps for coagulation of diminutive polyps of the colon. The rationale for diminutive polyp eradication is to destroy neoplastic tissue and possibly prevent colon cancer. However, convincing data to document a reduction in the incidence of colorectal cancer or even complete obliteration of all treated diminutive polyps with hot biopsy forceps are lacking. Complications of hot biopsy include hemorrhage, perforation, and post-coagulation syndrome. Tissue injury is deeper with monopolar hot biopsy forceps than bipolar forceps. The right colon is particularly susceptible to transmural injury and perforation. For small polyp obliteration, comparative studies of hot biopsy (monopolar and bipolar) with other techniques such as cold biopsy combined with thermal probes, large cup cold biopsy removal, and snare electrocoagulation are warranted. The necessity to biopsy typical appearing angiomata does not seem warranted on a routine clinical basis. The expected obliteration rates of small angiomata or rates of controlling lower gastrointestinal bleeding from colon angiomata after monopolar hot biopsy electrocoagulation have not been well documented. Heater probe or bipolar electrocoagulation have been safely and effectively applied to bleeding colon angiomata. These newer coagulation probes are recommended as an alternative to hot biopsy forceps for treatment of bleeding colonic angiomata.

Laser or electrocautery for laparoscopic cholecystectomy?

There are few concerns related to laparoscopic cholecystectomy that evoke as much emotion as the question of which is the superior energy source, laser or electrocautery. Monopolar radio frequency electricity (electrosurgery) and collimated coherent light (laser) injure tissue by the generation of heat, and in this regard are remarkably similar. The greatest differences between these sources of heat are related to predictability of injury, selective absorption of free beam laser energy, ability to coagulate, and cost. Although there are no prospective data yet available to answer the question of superiority, it appears that electrosurgical dissection may be faster and is generally less costly. Laser dissection may be more precise. In difficult cases, hemostasis appears to be superior with electrosurgery.

Endoscopic laser applications in the gastrointestinal tract

The Nd:YAG and, to a lesser degree, the argon laser have become valuable tools for the surgical endoscopist. Over the last 10 years, the impetus for application of these expensive instruments has changed from what the laser can do to what the laser can do better than less expensive technology. Whereas a few controlled randomized studies suggest that the Nd:YAG laser is better than no therapy and equivalent to other heat-producing instruments for control of upper gastrointestinal bleeding, such studies do not exist for other laser applications. Despite the lack of such studies, we remain convinced that, where available, lasers are the instrument of choice for palliation of unresectable mucosal-based cancers, coagulation of arteriovenous malformations, and ablation of certain adenomatous polyps in selected patients. New techniques on the horizon include the use of endoscopic photo-dynamic therapy for treatment of gastrointestinal cancers and endoscopic laser fragmentation of large common bile duct stones. The potential role for a nonthermal "endoscopic scalpel" is questionable because most gastrointestinal tissues are well vascularized; however, a pulsed laser capable of cutting and coagulation, such as the holmium:YAG laser, may be of some value for incisional endoscopic procedures.