Endoscopic applications of electrosurgery: a review of basic principles

Electrosurgical unit in GI endoscopy: the proper settings for practice

INTRODUCTION

Electrosurgical unit (ESU) is integral to the endoscopy unit. The proper knowledge of the Mode with setting is essential for good therapeutic outcomes and the safety of the patients.

AREAS COVERED

ESU generates high-frequency electric current, which could perform cutting and coagulation for various therapeutic interventions. We review the proper settings for common endoscopic interventions like hemostasis, polypectomy, sphincterotomy, and advanced procedures like endoscopic ultrasound-guided cysto-gastrostomy, bile duct drainage, and endoscopic Ampullectomy. We review the various waveforms of ESU in practice in endoscopy, including special conditions like patients with pacemakers.

EXPERT OPINION

Knowledge of the waveforms' duty cycle and crest factor is necessary. A high-duty cycle and lower crest factor lead to a good cutting effect on the tissue. Endocut is the most commonly used Mode in ESU in endoscopic practices like sphincterotomy and polypectomy. Endocut I mode (effect 1-2, duration 3, interval 3) is used for endoscopic sphincterotomy, while Forced Coag mode (Effect 2, 60 W) controls post-sphincterotomy bleeding. Endocut Q mode (Effect 2-3, duration 1, interval 3) is used for cutting the polyp, while Forced Coag mode (Effect 2, 60 W) is used before cutting for pre-coagulation of the stalk.

Understanding the Principles of Electrosurgery for Endoscopic Surgery and Third Space Endoscopy

Electrosurgery is the application of high-frequency electrical alternating current to biologic tissue to cut, coagulate, desiccate, and/or fulgurate. Electrosurgery is commonly used in gastrointestinal endoscopy, with applications including biliary sphincterotomy, polypectomy, hemostasis, the ablation of lesions, and endoscopic surgery. Understanding electrosurgical principles is important in endoscopic surgery to achieve the desired therapeutic effect, optimize procedural outcomes, and minimize risks or adverse events. This article describes fundamental principles that apply to electrosurgical units, operator technique, and practical considerations for achieving desired tissue effects in endoscopic surgery; and provides practical guidance and safety considerations when using electrosurgical units in endoscopic surgery.

Comparing the safety and effectiveness of dedicated radiofrequency transseptal wires to electrified metal guidewires

Background

Application of electrocautery to a metal guidewire is used by some operators to perform transseptal puncture (TSP). Commercially available dedicated radiofrequency (RF) guidewires may represent a better alternative. This study compares the safety and effectiveness of electrified guidewires to a dedicated RF wire.

Methods

TSP was performed on freshly excised porcine hearts using an electrified 0.014″ or 0.032″ guidewire under various power settings and was compared to TSP using a dedicated RF wire with 5 W power (0.035″ VersaCross RF System, Baylis Medical). The primary endpoint was the number of attempts required to achieve TSP. Secondary endpoints included the rate of TSP failure, TSP consistency, the effect of the distance between the tip of the guidewire and the tip of the dilator, and effect of RF power output level. Qualitative secondary endpoints included tissue puncture defect appearance, thermal damage to the TSP guidewire or dilator, and tissue temperature using thermal imaging.

Results

The RF wire required on average 1.10 ± 0.47 attempts to cross the septum. The 0.014″ electrified guidewire required an overall mean of 2.17 ± 2.36 attempts (2.0 times as many as the RF wire; p < .01), and the 0.032″ electrified guidewire required an overall mean of 3.90 ± 2.93 attempts (3.5 times as many as the RF wire; p < .01). Electrified guidewires had a higher rate of TSP failure, and caused larger defects and more tissue charring than the RF wire. Thermal analysis showed higher temperatures and a larger area of tissue heating with electrified guidewires than the RF wire.

Conclusion

Fewer RF applications were required to achieve TSP using a dedicated RF wire compared to an electrified guidewire. Smaller defects and lower tissue temperatures were also observed using the RF wire. Electrified guidewires required greater energy delivery and were associated with equipment damage and tissue charring, which may present a risk of thrombus, thermal injury, or scarring.

Bronchoscopic ablation techniques in the management of lung cancer

Central airway involvement is a common manifestation of lung cancer during the disease course. Some patients will require bronchoscopic therapeutic interventions to palliate symptoms, or less commonly to provide more definitive therapy of airway involvement. We describe an overview specifically of bronchoscopic ablative techniques that are available for use in malignant airway obstruction. Techniques that are more commonly used include bronchoscopic application of laser, electrocautery, argon plasma coagulation (APC), cryotherapy and mechanical debulking techniques. Less commonly employed are brachytherapy and photodynamic therapy. These techniques may be applied via flexible or rigid bronchoscopy depending upon the clinical scenario. The choice of technique depends on available tools and expertise, the urgency of the clinical scenario, and whether the lesion is predominately endobronchial, extrinsic compression, or a combination of both. Malignant airway obstruction is a common finding in lung cancer and there are a number of effective bronchoscopic ablative techniques that may be employed safely to palliate patients with a significant symptom burden.

Japan Gastroenterological Endoscopy Society guidelines for endoscopic sphincterotomy

The Japan Gastroenterological Endoscopy Society (JGES) has recently compiled guidelines for endoscopic sphincterotomy (EST) using evidence-based methods. Content regarding actual clinical practice, including detailed endoscopic procedures, instruments, device types and usage, has already been published by the JGES postgraduate education committee in May 2015 and, thus, in these guidelines we avoided duplicating such content as much as possible. The guidelines do not address pancreatic sphincterotomy, endoscopic papillary balloon dilation (EPBD), and endoscopic papillary large balloon dilation (EPLBD). The guidelines for EPLBD are planned to be developed separately. The evidence level in this field is often low and, in many instances, strong recommendation has to be determined on the basis of expert consensus. At this point in time, the guidelines are divided into six items including indications, techniques, specific cases, adverse events, outcomes, and postoperative follow up.

Endoscopic Instruments and Electrosurgical Unit for Colonoscopic Polypectomy

Colorectal polypectomy is an effective method for prevention of colorectal cancer. Many endoscopic instruments have been used for colorectal polypectomy, such as snares, forceps, endoscopic clips, a Coagrasper, retrieval net, injector, and electrosurgery generator unit (ESU). Understanding the characteristics of endoscopic instruments and their proper use according to morphology and size of the colorectal polyp will enable endoscopists to perform effective polypectomy. I reviewed the characteristics of endoscopic instruments for colorectal polypectomy and their appropriate use, as well as the basic principles and settings of the ESU.

From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy

Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP).

Interventional bronchoscopy in the management of thoracic malignancy

Educational Aims

Interventional bronchoscopy is a rapidly expanding field in respiratory medicine offering minimally invasive therapeutic and palliative procedures for all types of lung neoplasms. This field has progressed over the last couple of decades with the application of new technology. The HERMES European curriculum recommendations include interventional bronchoscopy skills in the modules of thoracic tumours and bronchoscopy [1]. However, interventional bronchoscopy is not available in all training centres and consequently, not all trainees will obtain experience unless they rotate to centres specifically offering such training.

In this review, we give an overview of interventional bronchoscopic procedures used for the treatment and palliation of thoracic malignancy. These can be applied either with flexible or rigid bronchoscopy or a combination of both depending on the anatomical location of the tumour, the complexity of the case, bleeding risk, the operator’s expertise and preference as well as local availability. Specialised anaesthetic support and appropriately trained endoscopy staff are essential, allowing a multimodality approach to meet the high complexity of these cases.

Interventional bronchoscopy is integral to the treatment and palliation of lung cancerhttp://ow.ly/R25w0

Electrosurgery in the Gastrointestinal Suite: Knowledge Is Power

Electrosurgery allows both cutting and coagulation of tissue and is an essential tool for therapeutic endoscopy. Electrosurgery is also the most commonly used and misunderstood technology by all surgical and medical disciplines. In other words, everyone uses it, but few understand it! The aims of this article are to (1) present a useful review of the fundamentals of electrosurgery technology; (2) relate the fundamentals to commonly performed flexible endoscopy procedures; and (3) provide a review of the safe application of grounding pads, careful management of accessories, and special patient safety considerations.

Detection and minimally invasive treatment of early squamous lung cancer

Non-small cell lung cancer (NSCLC) is the most common cause of cancer deaths worldwide. The majority of patents presenting with NSCLC have advanced disease, which precludes curative treatment. Early detection and treatment might result in the identification of more patients with early central lung cancer and improve survival. In addition, the study of early lung cancer improves understanding of lung carcinogenesis and might also reveal new treatment targets for advanced lung cancer. Bronchoscopic investigation of the central airways can reveal both early central lung cancer in situ (stage 0) and other preinvasive lesions such as dysplasia. In the current review we discuss the detection of early squamous lung cancer, the natural history of preinvasive lesions and whether biomarkers can be used to predict progression to cancer. Finally we will review the staging and management of preinvasive lung cancer lesions and the different therapeutic modalities that are available.

Iatrogenic perforation at colonic imaging

AIM

Adequate colonic imaging is generally an invasive procedure with attendant risks, particularly perforation. Endoscopy, barium enema and computed tomographic colonography (CTC) are the main techniques for investigating patients with symptoms of, or screening for, colorectal cancer. The potential complications of these investigations have to be weighed against the benefits. This article reviews the literature on the incidence, presentation and management of iatrogenic colonic perforation at colonic imaging.

METHOD

A literature review of relevant studies was undertaken using PubMed, Cochrane library and personal archives of references. Manual cross-referencing was performed, and relevant references from selected articles were reviewed. Studies reporting complications of endoscopy, barium enema and CT colonography were included in this review.

RESULTS

Twenty-four studies were identified comprising 640,433 colonoscopies, with iatrogenic perforation recorded in 585 patients (0.06%). The reported perforation rate with double-contrast barium enema was between 0.02 and 0.24%. Serious complications with CTC were infrequent, though nine perforations were reported in a case series of 24,365 patients (0.036%) undergoing CTC.

CONCLUSION

Perforation remains an infrequent and almost certainly under-reported, complication of all colonic imaging modalities. Risk awareness, early diagnosis and active management of iatrogenic perforation minimizes an adverse outcome.

A randomized controlled trial of electrocoagulation-enabled biopsy versus conventional biopsy in the diagnosis of endobronchial lesions

BACKGROUND

Although electrocoagulation at time of endobronchial biopsy can potentially reduce procedure-related bleeding during fiberoptic bronchoscopy (FOB), it can also impair quality of tissue specimen; credible data for either are lacking.

OBJECTIVE

To evaluate the impact of hot biopsy on the quality of tissue samples and to quantify the amount of procedure-related bleeding during endobronchial biopsy.

METHODS

In this single-center, prospective, single-blind, randomized controlled study we included adult patients referred for FOB and having endobronchial lesions. Patients were randomized to bronchial biopsy using an electrocoagulation-enabled biopsy forceps, with (EC+ group) or without (EC- group) application of electrocoagulation current (40 W for 10 s in a monopolar mode). Procedure-related bleeding was semi-quantified by observer description, as well as through a visual analogue scale. Overall quality of biopsy specimen and tissue damage were assessed and graded by a pulmonary pathologist blinded to FOB details.

RESULT

160 patients were randomized to endobronchial biopsy with (n = 81) or without (n = 79) the application of electrocoagulation. There were no severe bleeding episodes in either group, and severity of bleeding in the EC+ and EC- groups was similar (median visual analogue scale scores of 14 and 16, respectively). Histopathological diagnosis was similar in the EC+ and EC- groups (77.8% and 82.3%, respectively). There was no significant difference in tissue quality between the two groups.

CONCLUSION

Use of electrocoagulation-enabled endobronchial biopsy does not alter specimen quality and does not result in any significant reduction in procedure-related bleeding.

Monopolar electrosurgery on the extrahepatic bile ducts during laparoscopic cholecystectomy: an experimental controlled trial

INTRODUCTION

The purpose of this study is to investigate the occurrence of thermal injury in the extrahepatic bile ducts when monopolar electrosurgery is used to perform dieresis of the cystic duct and cystic vessels in laparoscopic cholecystectomy.

METHODS

Female pigs (n=40) of the Large White breed were separated into 2 groups of 20 animals. In the experimental groups, dieresis of the cystic duct and cystic vessels was performed with monopolar electrosurgery using a hook-like dissector using a power setting of 20 W, whereas in the control group this procedure was performed with a pair of Metzenbaum scissors disconnected from any kind of thermal energy source. Occurrence of distal thermal injury was evaluated on 2 occasions, on the 3rd and 28th days postoperatively. It consisted of exploratory laparotomy, cholangiography and both macroscopic and microscopic examination of the surgical specimen, which included cystic duct stump, hepatic duct and choledochus.

RESULTS

The presence of distal thermal injury, classified as second degree, 1.2 mm in the portion near the clipping area, was observed in only one of the cystic duct stumps after microscopic examination, without statistical significance. No thermal injury was observed in the extrahepatic bile ducts.

CONCLUSIONS

Monopolar electrosurgery produced negligible thermal injury in the extrahepatic bile ducts after laparoscopic cholecystectomy.

Electrosurgery in gastrointestinal endoscopy: principles to practice

An electrosurgery generator unit is a critical piece of equipment in any therapeutic endoscopy setting. Electrosurgery generators produce high-frequency alternating electric current and differ from electrocautery units in that both cutting and coagulation effects can be achieved. This ability to cut and coagulate at the same time makes electrosurgery an ideal therapeutic tool for gastrointestinal endoscopy. Although education and familiarity with these devices are accepted as the primary avenue to the safest and most effective clinical outcomes, concise information linking the basic properties of electrosurgery directly to clinical practice is not widespread. The following are the aims of this article: (i) to relate the fundamental electrosurgical principles to commonly performed procedures such as snare polypectomy, hot biopsy, sphincterotomy, bipolar hemostasis, and argon plasma coagulation, and (ii) to provide practical suggestions for the use of these devices on the basis of an understanding of electrosurgical principles and the available clinical data.

Diagnostic quality of: polyps resected by snare polypectomy: does the type of electrosurgical current used matter?

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Electrosurgery in the gastroenterology suite: principles, practice, and safety

An electrosurgery generator is a critical piece of equipment in any therapeutic endoscopy setting. Electrosurgery uses rapidly alternating current, provided by the electrosurgery generator, for both therapeutic cutting and coagulation of tissue. Basic variables important to electricity in general are also important to electrosurgery: current, voltage, circuit, and impedance (resistance). Monopolar and bipolar accessories (electrodes) are used in the endoscopy suite and these terms refer to the way in which the electric circuit is completed by the flowing current. Impedance resists current flow and changes with tissue type and degree of therapeutic coagulation. Waveforms are the high-frequency output selected by the operator when using an electrosurgery generator. Waveforms may be continuous or interrupted (modulated) and differ in voltage and degree of modulation. Certain waveforms are typically chosen for particular applications or accessories, such as polypectomy with a snare, because of predictable tissue-effect attributes of that waveform. Safe application of grounding pads, careful management of active accessories, and good care of electrosurgical equipment are crucial to patient and operator safety.

Rectal perforations after barium enema: a review

PURPOSE

Rectal injuries during barium enema are rare but life-threatening complications. The last review about this subject was published more than ten years ago. In the present review, we present an overview on the subject and especially focus on changes in treatment strategies and developments of less risky visualization techniques.

METHODS

A literature search was performed in the PubMed library using the key words-barium enema, complications, peritonitis, and rectal perforation-as well as related articles and other references obtained from these articles.

RESULTS

The most frequent cause of perforation is iatrogenic and catheter-related. Other causes are related to weakness of the colorectal wall or obstruction. Five types of perforations have been described: 1) perforations of the anal canal below the levator; 2) incomplete perforations; 3) perforations into the retroperitoneum; 4) transmural perforations into adjacent viscera; 5) perforations into the free intraperitoneal cavity. Most incomplete perforations and one-half of the retroperitoneal perforations have minimal clinical signs. Intraperitoneal perforations lead to the most catastrophic course, starting with rectal bleeding and mild abdominal complaints. This is rapidly followed by progressive sepsis and peritonitis, and leads to a high mortality rate. Surgery is not always required for intramural or small retroperitoneal perforations. These can be treated conservatively and require surgical debridement only in case of large amounts of extravasation or abscesses. Surgical repair of large rectal mucosal lesions or anal sphincter lesions is advised. Perirectal abscesses require drainage. Intraperitoneal perforations with gross extravasation need immediate aggressive surgical treatment in a critical care setting, because the threat of shock is high. Intraperitoneal perforations, neglected perforations, gross barium extravasation, poorly prepared colon, and venous intravasation of barium are prognostically unfavorable. The severest late complication in intraperitoneal perforations is ileus. Meticulous technical performance of the barium enema is the most important factor in prevention.

CONCLUSIONS

Rectal perforations after barium enema are rare. The overall mortality rate decreased in recent decades from approximately 50 to 35 percent as the result of advances in supportive and intensive care. Because of these advances, more aggressive surgical strategies were undertaken. With the advent of endoscopy, less barium enemas are performed. Consequently, the absolute incidence of complications has decreased. It is expected that in the future barium enemas will be replaced by more sensitive and less risky techniques, such as CT colonography and magnetic resonance colonography.

An animal model study to clarify and investigate endoscopic tissue coagulation by using a new monopolar device

BACKGROUND

The purpose of this study was to evaluate a new device for endoscopic monopolar electrocoagulation and to develop ablative techniques by using this new device.

METHODS

The new device consists of an overtube with a wire mesh electrode in an oval opening in the distal end and a balloon at the distal end. High-frequency electrical current was applied in 5 animal (swine) esophagi by using this specially designed monopolar electrocoagulation device. A total of 32 "lesions" were ablated by using blend electrosurgical waveforms for different time durations. The esophagi were then resected for histopathologic evaluation.

RESULTS

Histopathologic study of the ablated lesions demonstrated that, by using the monopolar electrocoagulation device, different levels of degeneration of the mucosa and submucosa were achieved. The method for use of the device is fast and easy to apply.

CONCLUSIONS

The ablative procedure with the new overtube device is minimally invasive, clearly feasible, and easy to apply. This new device potentially can be used in patients for tissue ablation.

A comparative study of postendoscopic sphincterotomy complications with various types of electrosurgical current in patients with choledocholithiasis

BACKGROUND

Whether the type of electrosurgical current used for endoscopic sphincterotomy influences the frequency of postsphincterotomy complications is unknown.

METHODS

One hundred eighty-six patients with choledocholithiasis were prospectively randomized to undergo endoscopic sphincterotomy with pure cutting current (n = 62, Group A), blended current (n = 62, Group B), or pure cutting initially followed by blended current (n = 62, Group C). Serum concentrations of amylase and lipase were evaluated in all patients 12 and 24 hours after sphincterotomy. Clinical pancreatitis was classified as mild, moderate, or severe. Postsphincterotomy bleeding was defined as a decrease in hematocrit of greater than 5%.

RESULTS

Serum concentrations of amylase and lipase were greater in Groups B and C at 12 and 24 hours after the procedure, as compared with Group A. Clinical mild pancreatitis occurred in 2 patients in Group A (3.2%), 8 in Group B (12.9%), and in 8 in Group C (12.9%). The differences were statistically significant for Group A compared with either Group B or Group C (p = 0.048). Postsphincterotomy bleeding occurred in 3 patients (1.6%), one in each group.

CONCLUSION

The use of pure cutting electrosurgical current during endoscopic sphincterotomy in patients with choledocholithiasis is associated with a lesser degree of pancreatic enzyme elevation and lower frequency of pancreatitis, whereas bleeding is not increased compared with blended current. Changing from pure cutting to blended current after the first 3 to 5 mm of the incision is associated with an increased rate of complications compared to the use of pure cutting current for the entire sphincterotomy.

Radiofrequency perforation in the treatment of congenital heart disease

Catheter-directed perforation of cardiac tissue with radiofrequency (RF) energy has expanded the horizon of the interventional cardiologist dealing with congenital heart disorders. The focus of the following discussion will be to detail the biophysical basis behind RF perforation and review its application in the management of congenital heart lesions.

Radio frequency perforation of cardiac tissue: modelling and experimental results

Radio frequency (RF) current delivered through a thin catheter can be used to perforate the pulmonary valve or the atrial septum to treat pulmonary atresia in newborns. To understand better the mechanisms of RF perforation, a numerical model is developed, and experiments are performed in isolated canine cardiac tissue. The model consists of a cylindrical domain with a tissue layer between two blood layers. The finite-difference method is used to compute both the potential and temperature distributions. When the tissue temperature exceeds 100 degrees C in all points that are directly in front of the catheter, these points are considered to be instantly vaporised, and the catheter advances over these points. The computed temperature time course coincides with measured temperature at small voltages (< 16 V). Simulated perforation occurs when the voltage exceeds a threshold of 70-80 V for a catheter diameter of 0.30-0.44 mm, which coincides with experimental observations in the myocardium. A voltage exceeding this perforation threshold tends to decrease tissue damage. Shorter electrodes (0.7 mm as against 2.4 mm) with smaller diameters produce a more rapid perforation. In conclusion, numerical simulations provide insights into aspects of RF perforation, such as electrode size, current, speed of perforation and collateral damage.

Tissue effects of bronchoscopic electrocautery: bronchoscopic appearance and histologic changes of bronchial wall after electrocautery

STUDY OBJECTIVES

To study tissue effects of bronchoscopic electrocautery (BE).

DESIGN

In six patients with non-small cell lung cancer, a BE procedure was performed immediately before surgery. After patients were placed on ventilation, normal mucosa on different carinae was treated with a cautery probe (2-mm(2) surface area) at a power setting of 30 W with a variable time of application of 1 to 5 s. Bronchoscopic appearance of the treated area was documented photographically, and histologic changes of the bronchial wall were examined.

SETTING

Bronchoscopy unit of a university hospital.

MEASUREMENTS AND RESULTS

BE resulted bronchoscopically in whitening of the bronchial mucosa with crater-shaped lesions. After longer duration of BE application, deeper craters with more profound charring were seen. Histologic changes of the lesions showed craters containing a variable amount of necrotic tissue. In one case, thin subsegmental carinae were coagulated and measurements could not be performed. In the remaining five cases, microscopic findings revealed 0.2 +/- 0.1-mm necrosis after 1 s; 0.4 +/- 0.2-mm necrosis after 2 s; 0.9 +/- 0.5-mm necrosis after 3 s; and 1.9 +/- 0.8-mm necrosis after 5 s. A variable degree of tissue damage surrounding the necrotic tissue area was found. In one case, cartilage damage appeared after 3 s of coagulation, and extensive damage of the underlying cartilage was seen in four cases after 5 s of application.

CONCLUSIONS

Superficial damage was obtained by short duration of BE (< or = 2 s), and longer duration of coagulation (3 s or 5 s) caused damage to the underlying cartilage. Bronchoscopic appearance after endobronchial electrocautery corresponded with the histologic changes.

Pure cut electrocautery current for sphincterotomy causes less post-procedure pancreatitis than blended current

BACKGROUND

Complications after endoscopic biliary sphincterotomy occur in 8% to 10% of patients when studied prospectively. It is not known whether the type of electrocautery current affects this rate. Theoretically, less edema of the ampulla after a pure cutting current sphincterotomy could decrease the risk of pancreatitis although the risk of postsphincterotomy hemorrhage might be greater.

METHODS

One hundred seventy patients undergoing sphincterotomy were prospectively randomized to either a blended or pure cut current on the Valleylab electrosurgical unit. The settings were a blended three current at a power setting of 30 watts/sec for both the cut and coagulation currents or a pure cut current at a power setting of 30 watts/sec. The individual determining whether a complication occurred was blinded to the type of current used, and all patients were hospitalized for 24 hours post-procedure. Pancreatitis was defined as mild if fewer than 5 days, moderate if 5 to 14 days, and severe if more than 14 days of hospitalization were required.

RESULTS

Indications for sphincterotomy were choledocholithiasis in 111 patients, sphincter of Oddi dysfunction in 36 patients, stent placement in 15 patients, and miscellaneous in 8 patients. There were a total of 16 complications in 170 patients (9%); 4 (5%) were in the pure cut current group of 86 patients (one episode of bleeding that required transfusion of 4 U and three episodes of mild pancreatitis), and 12 (14%) were in the blended current group of 84 patients (7 mild, 2 moderate, and 1 severe pancreatitis; 1 case of cholangitis; and one episode of bleeding that required transfusion of 2 U). There were significantly fewer complications in the pure cut group (p < 0.05 by chi-square).

CONCLUSION

The use of pure cut current is associated with a lower incidence of pancreatitis, the most common ERCP complication, than with blended current sphincterotomy. An insufficient number of patients were studied to comment on the relative risk of hemorrhage. However, because the complication of hemorrhage is much less common than pancreatitis, pure cut current is safer overall.

Consistent improvement in sphincterotome orientation with manual grooming

BACKGROUND

During ampullary cannulation with standard sphincterotomes, wire orientation is frequently to the right of 0 and can not always be rotated to the 12 o'clock ideal. It is not known if the presence of a wire guide alters a sphincterotome's orientation or if grooming in a standardized manner improves the orientation in the majority of cases.

METHODS

The intra-ampullary range of orientation of a double channel sphincterotome was prospectively evaluated before and after catheter grooming in 25 patients undergoing ERCP. The range of orientation was also measured with and without an indwelling biliary wire guide in 14 cases.

RESULTS

The maximal right orientation of the untrained sphincterotomes was 35 +/- 16 degrees; with a wire guide it was 33 +/- 22 degrees. Maximal left orientation was 17 +/- 16 degrees, wire guided it remained 19 +/- 14 degrees. Manual grooming shifted the mean maximal left orientation of the sphincterotomes to -37 +/- 28 degrees (p < 0.0001), permitting 80% of groomed sphincterotomes to achieve a 0 (12 o'clock) orientation and 100% to orient 10 degrees or less from zero.

CONCLUSIONS

The presence of the wire guide did not alter the orientation of the sphincterotome. Because manual grooming reliably improved the orientation of double-channel sphincterotomes, it should be routinely performed before their use.

Electrosurgical safety of guide wires during endoscopic sphincterotomy

A study was performed to determine whether alternate site electrosurgical burns could be caused by an inadequately insulated guide wire left in place during endoscopic papillotomy to maintain cannulation of the common bile duct. The safety of four covered guide wires and one standard guide wire was evaluated for electrosurgical safety. All four covered guide wires were coated with polyurethane or polytetrafluoroethylene (Teflon), providing insulation. Leakage currents under normal, limiting case, and fault (damaged insulation) conditions were compared to safety limits. All covered guide wires met safety limits under normal conditions, one of four covered guide wires met safety limits under limiting case conditions, and none met safety limits under fault conditions. The uncovered guide wire did not meet the safety limit under any conditions.

CONCLUSION

Without a well-insulated guide wire with intact coating, our measurements indicate that leaving a guide wire in place during papillotomy may result in an electrosurgical burn.

The interaction between electrosurgical generators, endoscopic electrodes, and tissue

Endoscopic monopolar and bipolar devices were compared during cutting and coagulation. It was observed on appropriate animal models that the initial resistance (impedance) values recorded correspond to the normal tissue impedance at the electrode. The subsequent impedance values increase 25 to 50 ohms for the coagulator which relates to tissue desiccation and for the cutting electrodes the impedance increases greater than 1000 ohms during the arcing process. At similar power settings, typical monopolar generators produce maximum power at 300 to 500 ohms while typical bipolar generators produce maximum power at 25 to 100 ohms. With impedances greater than 1000 ohms, monopolar generators are capable of higher power output than are bipolar generators. Since cutting is a high impedance process, bipolar cutting electrodes do not perform as intended with typical bipolar generators. Therefore, bipolar cutting electrodes should be employed with a monopolar generator or a generator designed specifically for their use.

Recognition and prevention of barium enema complications

The barium enema is a safe and accurate diagnostic study of the colon but, in rare cases, complications may result. Many of these can be prevented by proper equipment and careful attention to technique. When a complication does occur, prompt recognition and management is vital in decreasing morbidity and mortality. Perforation of the bowel is the most frequent serious complication, occurring in approximately 0.02% to 0.04% of patients. Rarely the colon may burst due to excessive transmural pressure alone. However, a colon weakened by iatrogenic trauma or disease is more likely to perforate during an enema than is a normal healthy bowel. Injury to the rectal mucosa or anal canal due to the enema tip or retention balloon is probably the most common traumatic cause of barium enema perforation. Inflation of a retention balloon within a stricture, neoplasm, inflamed rectum, or colostomy stoma is particularly hazardous. Recent deep biopsy or polypectomy with electrocautery makes the bowel more vulnerable to rupture. The tensile strength of the bowel wall is impaired in elderly patients, patients receiving long-term steroid therapy, and in disease states including neoplasm, diverticulitis, inflammatory bowel disease, and ischemia. Intraperitoneal perforation leads to a severe, acute peritonitis with intravascular volume depletion. The ensuing shock may be rapidly fatal. Prompt fluid replacement and laparotomy are essential. If the patient survives the initial shock and sepsis, later complications caused by dense intraperitoneal adhesions may develop. Extraperitoneal perforation is usually less catastrophic but may result in pain, sepsis, cellulitis, abscess, rectal stricture, or fistula. Intramural extravasation often forms a persistent submucosal barium granuloma which may ulcerate or be mistaken for a neoplasm. The most dramatic complication of barium enema is venous intravasation of barium. Fortunately, this is quite rare as it may be immediately lethal. Most cases have been attributed to trauma from the enema tip or retention balloon, mucosal inflammation, or misplacement of the tip in the vagina. Bacteremia has been found in as many as 23% of patients following barium enema and, in rare cases, may cause symptomatic septicemia. Other less common complications include barium impaction, water intoxication, allergic reactions, and cardiac arrhythmias. Preparatory laxatives and cleansing enemas have been implicated in some instances of dehydration, rectal trauma, water intoxication, and perforation. Careful review of the indications for examination, previous radiographs, and clinical history will identify many of the patients at greater risk for complications so that appropriate precautions may be observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Endobronchial electrocautery

Endobronchial electrocautery is a tool with diagnostic and therapeutic applications in the management of obstructing endobronchial disease. We have performed cautery procedures in 18 patients. Of these 18, five patients had benign diagnoses and 13 had malignancies. All patients with benign lesions had only endobronchial resections and four have done well. Four procedures resulted in the establishment of a diagnosis which had eluded other biopsy techniques. In 11 patients with malignant disease, electrocautery was used for palliation of airway obstruction, and in two patients, the snare was used as a biopsy technique. There have been no complications while utilizing the snare; however, application of electrocautery probes was associated with two complications. Our experience demonstrates the value and safety of using cautery wire snares to diagnose and treat endobronchial lesions.

Bipolar cautery for the fiberoptic bronchoscope

A bipolar electrocautery probe for use through the fiberbronchoscope has been designed and has proven useful in treating small endobronchial lesions and bleeding sites.

Endobronchial electrocautery

Endobronchial electrocautery was successfully used to treat three patients with major airway obstruction resulting from bronchogenic carcinoma and to establish a diagnosis in a fourth. Electrocautery was applied through fiberoptic bronchoscopes. In two cases, a wire snare was used to remove polypoid lesions and in two others, probes were used to ablate tumor tissue. As a result of high inspired oxygen concentration in one patient, a tracheal fire occurred without injury to the patient. Electrocautery is an available economical tool which has potential value in the diagnosis and therapy of endobronchial obstructing airway lesions.