Electrosurgical Generator Research Articles

MANAGEMENT OF ENDOSCOPIC SPHINCTEROTOMY‐INDUCED BLEEDING

Bleeding is one of the most common and potentially serious complications of endoscopic sphincterotomy (ES) and the overall frequency ranges from 2% to 5%. Patients with coagulopathy and anticoagulant therapy should be excluded from ES. ES using microprocessor‐controlled electrosurgical generator setting for Endocut mode, and a step‐wise manner of controlled incision may reduce the frequency of bleeding. Once ES‐induced bleeding occurs, diluted epinephrine irrigation, coagulation using papillotome, and balloon tamponade may be effective. If the bleeding continues, vessel ligation with a hemoclip should be performed to achieve a permanent hemostasis. Diluted epinephrine injection is an alternative technique when the point of bleeding is not identified. All endoscopists who perform ES should have suitable knowledge of management of bleeding and be experts in hemostasis.

Polypectomy devices

Polypectomy devices

Endoscopy in patients with implanted electronic devices

Endoscopy in patients with implanted electronic devices

Is the histologic quality of polyps affected by the type of electrosurgical generator used in resection?

Is the histologic quality of polyps affected by the type of electrosurgical generator used in resection?

Argon Plasma Coagulation for the Treatment of Superficial Esophageal Carcinoma

Recently, endoscopic mucosal resection (EMR) has become the first choice of treatment for superficial esophageal cancer without metastasis. However, EMR is not safe for all patients. Argon plasma coagulation (APC) is a noncontact electrocoagulation technique that creates tissue damage. The risk of bleeding may be lower with APC than with EMR. Therefore, we selected APC for the treatment of patients with superficial esophageal cancer who could not undergo EMR. The aim of the present study was to describe these cases and analyze the results of this treatment. Ten patients with superficial esophageal cancer underwent APC at our institution from February 2001 through January 2002. None of the patients could undergo EMR because of complications. Ablation was performed using an APC probe (ERBE APC probe; ERBE Elektromedizin, Tübingen, Germany), a high-frequency electrosurgical generator (ERBE ICC200), and an argon delivery unit (ERBE APC 300). All patients had uneventful recoveries. No incidents of bleeding from the ablated lesion or infection occurred. Oral intake was resumed on the day after treatment. The mean duration of the procedure was 20 minutes (range, 10 to 40 minutes). Disease recurred in two patients. Two patients died of laryngeal cancer and liver failure, respectively. APC is a safe and easy to perform procedure, but the effect of therapy is inferior to that of EMR in terms of the complete resection of the lesion. In conclusion, APC should be limited to cases of superficial esophageal cancer without metastasis in which EMR has been deemed difficult.

Diagnostic Quality of: Polyps Resected by Snare Polypectomy: Does the Type of Electrosurgical Current Used matter?

Traditionally, snare polypectomy is performed using blended, coagulation, or pure cutting electrical current (EC). The aim of this study was to assess and compare the diagnostic quality of polyps obtained by snare polypectomy using two different electrosurgical currents. Consecutive patients undergoing colonoscopy underwent polypectomy using either blended EC with a conventional electrosurgical generator (ESG) or using an ESG with a microprocessor that automatically controls cutting and coagulation (Endocut). An experienced blinded gastrointestinal (GI) pathologist evaluated the specimens for diameter, cautery damage (amount and degree), margin evaluability, architecture, and general histologic diagnostic quality. One hundred sixteen patients (69% men, mean age 63.8 +/- 15 yr) underwent 148 polypectomies (78 using blended current and 70 using Endocut). We found that the cautery degree was less with the Endocut than with the blended current (p < 0.02). Cautery amount was also higher in polyps resected using blended current (56%) than Endocut (51%) but this difference did not reach statistical significance (p= 0.1). Polyps resected using Endocut had better margin evaluability (75.7% to 60.3%, p= 0.046). The overall tissue architecture was similar in both groups. Polyps removed with blended current had less overall quality as compared to polyps removed by Endocut (p= 0.024). More extensive tissue damage occurred using blended EC with the conventional ESG than when using Endocut. The quality of the polypectomy specimens was overall better using Endocut. Finally, the ability to evaluate resected polyp margins and overall tissue histology was better with the microprocessor-controlled ESG than with the conventional ESG.

Colonic perforation after endoclip placement for delayed post–endoscopic-resection bleeding

Endoclip placement has the potential to provide effective hemostasis without the risk of perforation compared with thermal and certain injection methods when used to control post–endoscopic-resection (ER) bleeding.1 We present here a case of a patient who required a right hemicolectomy because of colonic perforation after endoclip placement for delayed post-ER bleeding in the ascending colon.

Ab Interno Trabeculectomy: Development of a Novel Device (Trabectome???) and Surgery for Open-Angle Glaucoma

To design an instrument to selectively remove trabecular meshwork and Schlemm's canal inner wall (SCIW), and demonstrate its effectiveness by histologic analysis of treated cadaveric human tissue. The design parameters of the instrument were the ability to permanently remove a segment of trabecular meshwork and Schlemm's canal inner wall without causing damage to surrounding tissue, and to allow use with standard anterior segment surgical techniques and equipment via an ab interno approach. Treatment was applied to 20 segments of human corneoscleral rims. The treated areas were examined using a confocal microscope and compared with matching areas in untreated controls and simulated goniotomy. The resultant instrument system surgically removes the trabecular meshwork and Schlemm's canal inner wall from an anterior chamber approach. It consists of a disposable surgical handpiece with irrigation, aspiration, and electrocautery to focally ablate the target tissues. The attached console includes a high-frequency (550 KHz) electrosurgical generator and irrigation/aspiration controlled by a foot pedal. Histologic examination of specimens treated with the Trabectome displayed disruption of the trabecular meshwork and Schlemm's canal inner wall without damage to surrounding structures. The specimens treated by simulated goniotomy displayed significant damage to the outer wall of Schlemm's canal and the surrounding sclera. The controls showed no disruption or damage to any tissues. The Trabectome system is designed for performing trabeculectomy via an ab interno approach. It successfully removed sections of trabecular meshwork and Schlemm's canal inner wall with less injury to the adjacent tissue compared with goniotomy knife in vitro. Theoretically, this procedure should provide direct access of aqueous humor to Schlemm's canal.

Mechanisms of thermal injury to the lower genital tract with radiofrequency resectoscopic surgery

Study objective Identification of mechanisms of thermal injury to the lower genital tract during radiofrequency (RF) resectoscopic surgery. Design Laboratory comparative study using uterovaginal tissue models. Setting University surgical laboratory. Patients No patients involved. Interventions A tissue model was created to simulate the uterus, contiguous posterior vaginal wall, and the introitus. Instrumentation included a RF electrosurgical generator; a continuous-flow resectoscope; and rollerball electrodes, both intact and with insulation defects created in a standardized fashion. The resectoscope was serially activated, varying electrode insulation defects and RF waveforms and wattage, both in open-circuit conditions, with or without cervical contact, and with variable amounts of the external sheath within the simulated cervical canal. The cervix was either overdilated or minimally dilated so that the surrogate cervical tissue was snug to the external sheath. After activation of the generator, the external sheath was brought into contact with the proximal vagina and perineum, any visible arcing was noted, and tissue effects were visually graded according to a zero-to-three scale. Measurements and main results When the resectoscope was in contact with the cervix, the prerequisites for vaginal injury included cervical overdilation, a proximal electrode insulation defect, and less than 2 cm of the external sheath in the canal. There was greater risk with larger electrode insulation defects located beside the telescope, and there was a greater degree of coupling and injury with high voltage outputs. Conclusion The incidence of vaginal and perineal burns associated with unipolar RF resectoscopes can likely be minimized by careful attention to technique.

A Randomized Trial of Endoscopic Biliary Sphincterotomy Using Pure-Cut Versus Combined Cut and Coagulation Waveforms

Endoscopic biliary sphincterotomy has complication rates of 5%-12%. The output from the electrosurgical generator may influence the degree of coagulation and the rapidity of the incision, and thus rates of pancreatitis, hemorrhage, and perforation. Some modern generators incorporate feedback control to standardize output and automate the alternating cut and coagulation modes. Our aim was to compare 2 feedback-controlled generators, one with constant pure cutting-type output and the other with an alternating cut and coagulation mode. In this multicenter randomized study, 133 patients were assigned to the alternating cut/coag output and 134 patients were assigned to constant pure-cut output. Patients were stratified by their risk for pancreatitis. The overall pancreatitis rate was 1.5%, including 3 patients in the cut/coag group and 1 patient in the pure-cut group (P>.05). There were 11 poorly controlled (zipper) incisions in the pure-cut group and none in the cut/coag group (P=.02). The incision was completed in all patients without stalling. Immediate hemorrhage occurred in 35 pure-cut patients and 8 cut/coag patients output (P=.002). There were no episodes of clinically significant bleeding, delayed bleeding, or perforation. Biliary sphincterotomy using feedback-controlled generators results in dependable progression of incision with a low pancreatitis rate. Control of the incision is improved subjectively with the cut/coagulation output, but this did not translate into a difference in clinically significant complications.

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Post-sphincterotomy bleeding after the introduction of microprocessor-controlled electrosurgery: does the new technology make the difference?

Bleeding as a complication of endoscopic sphincterotomy is influenced by several factors. The objective of this study was to compare rates of bleeding after sphincterotomy performed with two different electrosurgical current generators (Valleylab SSE2L and ERBE ICC200). A total of 6179 consecutive reports of ERCP were analyzed to compare the frequency of endoscopically and clinically evident bleeding after sphincterotomy when using the Valleylab SSE2L generator (from February 1994 to November 1997) and the ERBE ICC200 generator (from December 1997 to September 2000). Relevant risk factors were assessed by univariate analysis and significant predictors were included in a multiple logistic regression model. A total of 2711 sphincterotomies were performed in 2309 patients (1749 biliary, 962 pancreatic). Endoscopically observed bleeding occurred in 68 patients (5.5%) in the ValleyLab group and 13 (1.2%) in the ERBE group. The ValleyLab generator was independently associated with an increase in endoscopically observed bleeding (OR 4.02: 95% CI[2.13, 7.61], p <0.001). There was no significant difference in clinically evident bleeding between the two groups. Use of the microprocessor-controlled ERBE electrosurgical generator for endoscopic sphincterotomy was associated with a significantly lower frequency of endoscopically observed bleeding but not clinically evident bleeding.

Efficacy and safety of argon plasma coagulation for the treatment of hemorrhagic radiation proctitis

To evaluate the efficacy, safety and medium-/long-term clinical course of patients undergoing endoscopic treatment with argon plasma coagulation for hemorrhagic radiation proctopathy. Descriptive, retrospective study with medium- and long-term follow-up. Ten patients were treated with argon plasma coagulation for hemorrhagic radiation proctopathy between July 1998 and February 2003. Inclusion criteria were: evidence of chronic rectal bleeding, consistent endoscopic findings, and absence of any other cause of hematochezia after a comprehensive ano-rectal examination and complete colonoscopy. The equipment used was a standard colonoscope, an argon delivery unit, an argon plasma coagulation probe 1.5 mm in internal diameter, and a high-frequency electrosurgical generator. Consecutive treatment sessions were programmed whenever it was considered necessary until all mucosal lesions had been treated. Clinical and evolutive follow-up was performed with a focus on tolerance, efficacy, and potential argon plasma coagulation-related complications. Data were updated by personal or telephonic interview. In all patients, chronic rectal bleeding stopped after the last treatment session. The mean number of treatment sessions to stop symptoms was 1.7. Mean follow-up was 31.1 months. All sessions were well tolerated, similarly to standard rectoscopy. In one case a recurrence of rectal bleeding was observed four months later, which required two repeat sessions. Four patients were anemic at inclusion. Three of them reported a resolved anemia at the end of the study. No delayed argon plasma coagulation-related complications such us ulcers or strictures were seen. Argon plasma coagulation appears to be a useful, effective and safe treatment for rectal bleeding resulting from chronic radiation proctitis when compared to standard medical and endoscopic treatments. These successful outcomes seem to persist even after long-term follow-up.

A CASE CONTROLLED STUDY TO COMPARE A CONVENTIONAL ELECTROSURGICAL GENERATOR TO ONE WITH ENDOCUT® IN PERFORMING SNARE POLYPECTOMY

Purpose: There are no previous studies comparing safety of electrosurgical generators (ESG) in performing snare polypectomy. Furthermore, there are no studies looking at the use of Endocut® in performing snare polypectomy. We conducted a retrospective case controlled study to compare a conventional ESG to a newer ESG with the Endocut® feature. Methods: At our institution, a conventional ESG utilizing blended current was used for all snare polypectomies up to February 28, 2001. A retrospective case controlled chart review was performed of all patients undergoing colonoscopy from August 27, 1999 through September 9, 2002. The inclusion criteria encompassed all patients who underwent snare polypectomy during colonoscopy performed for the usually recommended indications. Data collection included patient demographics, number of polyps removed, polyp characteristics, immediate and delayed complications related to the polypectomy. The case controls consisted of 150 cases that underwent snare polypectomy using the conventional ESG prior to February 28, 2001. After this date, 150 consecutive cases that underwent snare polypectomy with the newer ESG utilizing blended current with the Endocut® feature were also analyzed. All polypectomies were performed using the same type of monopolar snare with standard manufacturer recommended settings. Results: A total of 311 polyps were excised with the conventional ESG of which 255 were removed with snare. Average size of the polyps was 7.4 mm. In this group, there were 4 (2.67%) complications. All complications were post polypectomy bleeds; 2 immediate and 2 delayed. In the newer ESG with Endocut® group, 375 polyps were removed of which 263 were excised using snare. Average size of the polyps was 7.6 mm. In this group, there was 1 (0.67%) post polypectomy bleed. The groups did not differ significantly in their demographics, comorbid conditions or polyp characteristics. Conclusions: In our study, the newer ESG with the Endocut® feature did not provide statistically significant clinical benefit in complication rates (P = 0.22). This can be explained by the limited sample size. The data does lean towards statistical importance warrenting further study. A prospective randomized trial using larger number of patients may show statistically significant benifit in the complication rates of one ESG over the other.

A comparison of depth of tissue injury caused by different modes of electrosurgical current in a pig colon model

Background This study compared tissue injury produced by 3 types of electrosurgical current (pure cut, coagulation, blend) and two different procedures (snare and “hot biopsy”). Methods Each type of electrosurgical current was passed through the colon of a live pig by means of a snare or “hot biopsy” forceps, and the depth of tissue injury was determined histologically. The high-frequency electrosurgical current was provided by a single electrosurgical generator. The peak power for each type of current was determined with an oscilloscope. Results The depth of tissue injury caused by coagulation current was significantly greater compared with blended current ( p = 0.0157). The depth of injury with coagulation current also was greater than with pure cut current, ( p = 0.0461 in a single statistical test; significance removed by Bonferroni-Dunn correction). With the hot biopsy forceps, the depth of tissue injury was deeper compared with that produced with a snare, regardless of the diameter of the snare loop. Peak power at a setting of 30 W was 1154 W for coagulation, 90.2 W for pure cut, and 227.8 W for blend current. Conclusions When a high-frequency electrosurgical current device is used, use of a cutting current in the blend mode is recommended instead of coagulation current because this waveform is suitable for incision and provides effective hemostasis. Skillful technique is required for safe use of a hot biopsy forceps, because there is a significant potential for deeper tissue injury with this device.

Patterns of bleeding after endoscopic sphincterotomy, the subsequent risk of bleeding, and the role of epinephrine injection.

The patterns of bleeding following endoscopic sphincterotomy (ES) and their predictive value for subsequent bleeding are poorly understood. Similarly, the efficacy and side effects of epinephrine (E) injection for persistent bleeding have not been well studied. Over a 44-month period, all patients undergoing ES were prospectively assessed and followed-up. The character of bleeding (pulsatile, oozing, trickle, none) was recorded immediately, 5 minutes following ES and at the completion of the procedure. Patients with persistent bleeding at the time the procedure was completed (5 minutes or greater) received E injection(s) (1:10,000 concentrations) into the bleeding point with a sclerotherapy needle. ES was performed in all patients with a single electrosurgical generator Valleylab (Force 1B) using pure cutting current. 506 patients (68% females, mean age 54 years) who underwent 550 ES were studied. Bleeding patterns immediately following ES were: 6% pulsatile, 42% oozing, 27% trickle, and 24% none. E (median 0.5 cc; range 0.5-4 cc total) was injected during 79 procedures (14%); none of these patients had complications nor delayed bleeding. For all patients, delayed bleeding occurred in 8 (1.6%, 95% CI 0.57-0.0269); of these 8 delayed bleeders, 1 had no bleeding after ES, and only 1 had any bleeding at 5 minutes. The only variable associated with bleeding after ES was abnormal labs (thrombocytopenia, elevated creatinine concentration, hypoprothrombinemia). The pattern of bleeding following ES may not predict the risk of late bleeding. Abnormal labs are associated with visible bleeding. Epinephrine injection is safe and appears to provide effective hemostasis.

Comparison of Wound-Healing Characteristics with Feedback Circuit Electrosurgical Generators in a Porcine Model

The type of incisional instrument used to create a surgical wound can influence the rate of wound healing and overall wound strength. The purpose of this study was to evaluate several facets of wound healing within incisions created in the small intestine, uterus, and skin in a porcine model by using feedback circuit electrosurgical generators and a standard steel scalpel blade in a porcine model. Eighteen pigs were evaluated by creating surgical incisions in the skin, uterus, and small intestine utilizing 2 computerized electrosurgical generators (FX, ValleyLab, Boulder, CO, and PEGASYS, Ethicon Endo-Surgery, Inc., Cincinnati, OH) and a scalpel blade. All incisions were reapproximated with absorbable suture. Incision sites were evaluated histologically at 3, 7, or 14 days postincision according to randomization. The skin and small intestine samples were tested for wound tensile strength at 7 and 14 days. There were no statistically significant differences demonstrated with tensile strength testing comparing the electrosurgical devices to the scalpel-blade incisions for skin or small intestine at all time points. The only significant difference detected with respect to wound tensile strength was when different organ types were compared, regardless of device used (i.e., skin, 19.5 N/cm2 vs. small intestine, 5.78 N/cm2). Histologic evaluation demonstrated that the wounds created by the electrosurgical generators displayed decreased overall wound healing at 3, 7, and 14 days compared to the scalpel group. These findings indicate that the electrosurgical devices tested delay wound healing at the surgical site, but fail to demonstrate any significant difference in overall wound tensile strength. Wound healing may occur at a more rapid rate when a traditional scalpel blade is used to create the surgical incision, but no difference in global wound dynamics could be detected.

Factors Affecting Capacitive Current Diversion with a Uterine Resectoscope: An In Vitro Study

Study Objective To evaluate electrosurgical waveform, generator type, and electrode integrity as variables in capacitive induction of current on the external sheath of a resectoscope in open-circuit conditions. Design In vitro, laboratory, comparative study (Canadian Task Force classification CII-1). Setting Surgical laboratory Instrumentation Three ValleyLab radiofrequency (RF) electrosurgical generators (ESU), Force-2, Force-4, and Force-F/X; a resectoscope (Storz 50 series); and rollerball electrodes, both intact and with two types of standard insulation defects (lateral and circumferential) placed in two locations: distally, beyond the end of the telescope, and proximally, beside the distal aspect of the telescope. A Dynatek ESU analyzer was used to record current and wattage on electrodes and the external sheath. Measurements and Main Results With intact insulation, current was not disproportionately induced on the external sheath of the resectoscope regardless of ESU, power, or waveform. Proximally located electrode insulation defects allowed induction of most of the generator's output to the external sheath when high-voltage modulated outputs were used, and the risk varied somewhat with the ESU. There was no such induction at any power setting or with any insulation defect when low-voltage (cutting) outputs were tested. Conclusion In the presence of proximal electrode defects, high-voltage currents may contribute to thermal injury to the lower genital tract during RF resectoscopic surgery.

Electrosurgical generators: MAY 2003

In order to promote the appropriate use of newer emerging technologies, the American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee has developed a series of status evaluation papers. This process presents relevant information about these technologies to practicing physicians for the education and care of their patients. In many cases, data from randomized, controlled trials is lacking and only preliminary clinical studies are available. Practitioners should continue to monitor the medical publications for subsequent data about the efficacy, safety, societal, and economic aspects of the technologies.

Basic and clinical studies of percutaneous radiofrequency ablation ofosteoid osteoma using a standard electrosurgical generator

For percutaneous radiofrequency ablation of osteoidosteoma for pain management, we used a standardelectrosurgical generator instead of the radiofrequency generatorsystem. First, we used the standard electrosurgicalgenerator to determine the diameter of the coagulated areaof normal femurs and humeruses of dogs under generalanesthesia and to detect damage to normal tissue around thebone. We then used a standard electrosurgical generator toperform percutaneous radiofrequency ablation of the osteoidosteoma. All three patients were almost pain-free within thefirst 24 h after the procedure, and they were discharged theday after the operation, being hospitalized for only 2 days. Wethus confirmed that percutaneous radiofrequency ablationusing a standard electrosurgical generator produced resultssimilar to those achieved with the radiofrequency generatorsystem.