- Email: [email protected]
Snare tip soft coagulation achieves effective and safe endoscopic hemostasis during wide-field endoscopic resection of large colonic lesions (with videos)
Snare tip soft coagulation achieves effective and safe endoscopic hemostasis during wide-field endoscopic resection of large colonic lesions (with videos) Farzan Fahrtash-Bahin, MPhil, MBBS (Hons), Bronte A. Holt, BMSc (Hons), MBBS (Hons), FRACP, Vanoo Jayasekeran, MBBS, MRCP, PhD, Stephen J. Williams, MD, MBBS, FRACP, Rebecca Sonson, BN, Michael J. Bourke, MBBS, FRACP Westmead, Sydney, New South Wales, Australia
Background: Wide-field EMR (WF-EMR) of large colonic lesions exposes submucosal vessels, which may result in intraprocedural bleeding (IPB). Ongoing bleeding may obscure the endoscopic field, prolonging the procedure and reducing safety and accuracy. A number of potential interventions to control bleeding exist; however, they have inherent limitations. Safe, readily applicable, inexpensive, and effective therapy to control EMR-IPB has not yet been described. Objective: To evaluate the safety and efficacy of the snare tip soft coagulation (STSC) technique to control IPB after WF-EMR of large colonic lesions. Design: Single-center, prospective cohort study. Setting: Tertiary care referral center. Patients: A total of 196 patients undergoing wide-field colonic EMR for flat and sessile lesions 20 mm or larger. Interventions: A standard inject-and-resect EMR technique was applied. IPB was defined as bleeding obscuring the endoscopic field that persisted for 60 seconds or longer. STSC was performed by using the tip of the polypectomy snare to apply soft coagulation (80 W) to sites of IPB. Main Outcome Measurements: Immediate hemostasis, postprocedural bleeding, and other adverse events. Results: A total of 198 lesions (mean size 41.5 mm, 64% in the right colon) were removed in 196 patients (mean age 68 years, 52.5% male). STSC alone achieved effective hemostasis in 40 of 44 cases of IPB (91%). In the remaining 4 cases, additional treatment with coagulating forceps or clips was required to achieve hemostasis. There were no immediate STSC-related adverse events. There was no statistically significant difference between the IPB and non-IPB groups in relation to the use of antiplatelet (P Z .2) or anticoagulation agents (P Z .4), postprocedural bleeding (P Z .8) and adverse event rates (P Z .7). Limitations: Nonrandomized study. Conclusions: STSC is a simple and efficient first-line technique for achieving hemostasis of IPB during WF-EMR in the colon. It succeeds in the majority of cases and appears to be safe.
Abbreviations: AMN, advanced mucosal neoplasia; EMR-IPB, EMRrelated intraprocedural bleeding; IPB, intraprocedural bleeding; STSC, snare tip soft coagulation; WF-EMR, wide-field EMR.
Copyright ª 2013 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2013.02.030
DISCLOSURE: The authors disclosed no financial relationships relevant to this publication.
Received December 15, 2012. Accepted February 20, 2013.
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Current affiliations: Department of Gastroenterology and Hepatology, Westmead Hospital, Westmead, Sydney, New South Wales, Australia. Reprint requests: Michael J. Bourke, MBBS, FRACP, Department of Gastroenterology and Hepatology, Westmead Hospital, Westmead, Sydney, NSW 2145, Australia. If you would like to chat with an author of this article, you may contact Dr Bourke at [email protected].
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Fahrtash-Bahin et al
Wide-field EMR (WF-EMR) is a safe, cost-effective, and clinically efficacious therapy for advanced mucosal neoplasia (AMN) (large sessile polyps and laterally spreading tumors O20 mm) of the colon.1-3 This type of endoscopic therapy results in a mucosal defect of at least 20 mm and as large as 100 mm and occupying between one fourth of and the entire circumference of the bowel wall. Consequently, there are often numerous exposed submucosal vessels that may be transected or injured during the EMR procedure and result in intraprocedural bleeding (IPB) (which may arise from within or at the margin of the defect). EMR-related IPB (EMR-IPB) is predominantly nonspurting. Bleeding may be self-limited, but is not always so and often obscures the endoscopic field, prolonging the procedure and reducing safety and accuracy. A number of potential interventions to control bleeding exist. These include injection of epinephrine, forceps, or argon plasma electrocoagulation and endoscopic clipping. They all have inherent limitations. Our hypothesis is that snare tip soft coagulation (STSC) is a highly effective, safe, and readily applicable technique for the control of EMR-IPB.
METHODS Between January 2011 and September 2012, a subgroup of patients referred for WF-EMR of AMN consented to participate in this observational cohort study. The study was approved by the hospital research ethics committee (SAC2010/5/4.9(3155) AU RED HREC/10/WMEAD/103). Patients were asked to withhold antiplatelet agents 7 days before the procedure. Anticoagulants were managed in accordance with current American Society for Gastrointestinal Endoscopy guidelines.4 Two senior endoscopists (MJB, SJW) with extensive EMR experience or 2 senior fellows under their direct supervision performed all procedures by using a standardized inject-and-resect technique and a microprocessor-controlled electrosurgical generator (VIO 300D; ERBE Elektromedizin, Tübingen, Germany).2,5,6 The submucosal injectate composed of succinylated gelatin (Gelofusine; B. Braun Australia Pty Ltd, Bella Vista, Australia) with indigo carmine blue (80 mg/ 500 mL solution) and 1:10,000 epinephrine (1 mL/10-mL injection).7 EMR-IPB was defined as oozing or spurting of blood persisting for longer than 60 seconds and not responding to water jet irrigation. The primary endpoint was effective hemostasis, defined as complete cessation of bleeding. Secondary endpoints included clinically significant postprocedural bleeding (defined as occurring at any time within 2 weeks after the procedure and requiring hospital admission) and immediate and delayed adverse events. Statistical analysis was performed by using SPSS software version 20 (IBM, Chicago, Ill). The Mann-Whitney U test was applied for comparison of continuous variables, and the c2 or Fisher exact test was used for comparing www.giejournal.org
Snare tip soft coagulation
Take-home Message Intraprocedural bleeding during EMR of large colonic lesions obscures the endoscopic view and may compromise the accuracy and safety of the procedure. Soft coagulation through a snare tip is a readily available, effective, and safe hemostatic modality for intraprocedural bleeding.
dichotomous variables. A 2-tailed P value of !.05 was considered significant. Two patients had 2 colonic lesions undergoing resection, and 1 lesion was selected at random for the purpose of analysis.
Electrophysiological principles During STSC, electrical energy from the snare tip is converted to thermal energy, which leads to tissue desiccation and vessel coagulation. The amount of heat transferred to each point in the tissue (per unit of time) is given by the product of the square of the current density and resistance. Current density refers to the amount of current passing through a given unit area.8,9 Peak voltage output for the SOFT COAG mode is capped at 190 V in the ERBE VIO system.10,11 Ohm’s law states that current is equal to the quotient of voltage and resistance. As the tissue is desiccated, the resistance to current increases exponentially within a fraction of a second, and because voltage is fixed, theoretically current can no longer flow. In practice, once the tissue is coagulated, further applications of STSC do not result in any endoscopically appreciable tissue effect. This is a theoretical key built-in safety mechanism of the SOFT COAG mode. Basically, effective tissue desiccation terminates energy transfer and limits any further tissue injury. In contrast, with traditional coagulation modes with higher peak voltages, current may be forced through already desiccated tissue, leading to deep thermal injury. (See Appendix, available online at www. giejournal.org.)
Technique STSC has been increasingly used in our department to control IPB for the past 4 years. In this study, it was performed as demonstrated in Videos 1 and 2 (available online at www.giejournal.org). Monopolar SOFT COAG at 80 W Effect 4 was used (VIO 300D; ERBE Elektromedizin). The snare tip is positioned 1 to 2 mm beyond the end of the snare sheath. The wire tip is applied directly and gently (it is a contact technique) to the bleeding point and the (blue) diathermy pedal depressed for 1 to 2 seconds. This results in energy transfer and coagulation of the vessel. The ERBE device limits voltage output to less than 190 V. Snares were either 20 mm spiral (wire diameter 0.48 mm; Olympus Corporation, Tokyo, Japan) or 30 15-mm mini-snare (wire diameter 0.3 mm; Cook Medical, Browns Plains, Volume 78, No. 1 : 2013 GASTROINTESTINAL ENDOSCOPY 159
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Australia). The number of snare tip coagulations was at the discretion of the endoscopist. It can be repeated as many as 5 times to achieve hemostasis. If bleeding persists, additional applications beyond this number are unlikely to succeed.
Fahrtash-Bahin et al
Intraprocedural hemostasis is a highly relevant, yet underdocumented aspect of advanced endoscopic resection. In our cohort, IPB developed in 24% of patients undergoing WF-EMR for colonic AMN. Kim et al13 reported an immediate postpolypectomy bleeding (IPPB) rate of 2.8% in a cross-sectional study of an unselected cohort of 9336 polypectomies for colonic lesions larger than 4 mm. On multivariate analysis, polyp size greater than 10 mm, age 65 years and older, laterally spreading
tumors, or pedunculated morphology and use of blended current and anticoagulants were some of the factors associated with IPPB. The mean size of lesions in the IPPB group was 13.2 mm compared with 50.9 mm in our cohort of IPB. Effective control of EMR-IPB maintains clear endoscopic visualization and may improve procedure time and safety. The modern endoscopist has a broad range of potential hemostatic therapies, including epinephrine injection, endoscopic clips, and argon plasma and forceps coagulation. Epinephrine is already a component of injection solutions in many centers. Further injection of epinephrine around bleeding vessels is often not effective and may lead to tissue ischemia locally or systemic cardiovascular sequelae.14 Placement of clips intraprocedurally may impair completion of EMR, especially if the bleeding involves a site with remaining pathology. Furthermore, clips may not be the ideal hemostatic technique for small bleeding vessels because of insufficient compression of the target vessel. The colon, especially in a proximal location, is relatively thin and susceptible to deep injury or even perforation as a result of excessive deep thermal injury from forceps or argon plasma electrocoagulation. There is also additional procedure time (related to device exchange) and expense associated with the use of these modalities. In our cohort of 47 patients, immediate hemostatic control with STSC monotherapy was achieved in 91% of lesions without adverse events. Although we use STSC as first-line therapy, even in brisk bleeding, in 3 patients (6.4%) with brisk pulsatile bleeding, coagulating forceps alone were used for hemostasis. The safety of STSC is underpinned by the electrophysiological principles outlined previously. Because peak voltage is fixed, tissue resistance increases swiftly once desiccation of the target tissue is achieved, halting or severely attenuating further energy transfer and thus minimizing the risk of deep thermal injury.15 STSC is furthermore a very cost- and timeeffective technique using the polypectomy snare for hemostasis as well as resection. It is important to note that this feature does not apply to conventional or forced coagulation in which the maximum voltage is not capped and the risk of deep tissue injury is always present. We acknowledge some limitations of this study, including the lack of randomization and procedures being performed at a single academic tertiary center. Furthermore, the endoscopist needs a dedicated electrosurgical unit that has soft coagulation capabilities. In conclusion, STSC is a readily available, highly effective, and economically sound technique for the management of EMR-IPB. There are multiple benefits, including the absence of device exchange, resulting in decreased procedure time and no added cost. The technique is simple to use, rapidly used, and highly efficient. We believe STSC to be a valuable addition to the current options for EMR-IPB and possibly the best first-line therapy.
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RESULTS A total of 198 lesions were removed in 196 patients (Table 1). The mean age was 68.0 years and 52.6% of patients were male. The mean lesion size was 41.5 mm (range 20-120 mm). Of the patients, 54.1% had lesions located in the right colon. Twenty-five (12.8%) and 6 (3.1%) patients were receiving antiplatelet and warfarin therapy, respectively. The mean time of cessation of aspirin, clopidogrel, and warfarin was 5, 6.5, and 4.3 days, respectively. Forty-seven patients (24.0%) had IPB. The bleeding was at the mucosal incision edge in 17 lesions (36.2%), within the defect in 28 lesions (60.0%), and at both sites in 2 lesions (4.3%). On multivariate analysis, larger lesion size predicted IPB (P Z .01). Hemostasis was achieved in 40 of 44 cases (90.9%) of IPB by using STSC alone. In the remaining 4 cases, alternative or additional therapy was required for hemostasis. In 2 cases each, either clips or coagulating forceps were required in addition to STSC. In 3 cases of brisk pulsatile bleeding, coagulating forceps alone were used (Figs. 1 and 2, Videos 1 and 2). EMR was completed in all 47 lesions. No adverse events occurred related to STSC (Table 1). The postprocedural bleeding rate and adverse events in the IPB group treated with STSC were not statistically different from those in the non-IPB group. Specifically, 1 intraprocedural perforation occurred in the non-IPB group compared with none in the IPB group (P Z .73). This was attributed to muscularis propria resection. A muscularis propria defect (evidenced by the target sign12) occurred in 3 IPB cases compared with 5 non-IPB cases (P Z .07). These patients were managed intraprocedurally with clips and had no significant adverse outcomes. The site of IPB (ie, at the edge or within the resection defect) did not influence the response to treatment, nor was it associated with adverse events, including postprocedural bleeding and perforation.
DISCUSSION
Fahrtash-Bahin et al
Snare tip soft coagulation
TABLE 1. Characteristics of patients, lesions, and periprocedural compilations Total (N [ 196)
IPB (n [ 47)
No IPB (n [ 149)
P value
68.0 (22-93)
66.4 (42-88)
68.5 (22-93)
.29
103 (52.6)
24 (51.1)
79 (53.0)
.82
93 (47.4)
23 (48.9)
70 (47.0)
41.5 (20-120)
50.9 (20-120)
38.6 (20-100)
.01
Left side of the colon
90 (45.9)
24 (51.1)
57 (38.3)
.07
Right side of the colon
106 (54.1)
23 (48.9)
92 (61.7)
0-IIaþIs
62 (31.6)
25 (53.2)
37 (24.8)
0-Is
17 (8.7)
4 (8.5)
13 (8.7)
0-IIa
91 (46.4)
12 (25.5)
79 (53.0)
0-IIb
11 (5.6)
2 (4.3)
10 (6.7)
0-IIaþIIb
3 (1.5)
0
3 (2.0)
0-IIc or 0-IIaþc
3 (1.5)
4 (8.5)
7 (4.7)
116 (59.2)
29 (61.7)
86 (57.7)
Nongranular
65 (33.2)
15 (31.9)
50 (33.6)
Mixed
14 (7.1)
3 (6.4)
11 (7.4)
1 (0.5)
0
1 (0.7)
TA
44 (22.4)
6 (12.8)
38 (25.5)
TVA
103 (52.6)
33 (70.2)
70 (47.0)
SSA
22 (11.2)
2 (4.2)
20 (13.4)
TSA
3 (1.5)
0
3 (2.0)
15 (7.7)
4 (8.5)
11 (7.4)
9 (4.6)
2 (4.3)
7 (4.7)
Total
25 (12.8)
6 (12.8)
19 (12.6)
Aspirin
16 (8.2)
4 (8.5)
12 (7.9)
Clopidogrel
8 (4.1)
2 (4.2)
6 (4.0)
Dual
1 (0.5)
0
1 (0.7)
Warfarin
6 (3.1)
2 (4.3)
4 (2.0)
.41
Muscularis propria defect
8 (4.1)
3 (8.5)
5 (3.4)
.07
Free perforation
1 (0.5)
0
1 (0.7)
.73
11 (5.6)
2 (4.3)
9 (6.0)
.79
Age (range), y Sex Male Female Mean lesion size, mm Location
Paris classification .01
Morphology Granular
Unclassifiable
.93
Final histology
Carcinoma Mixed
.19
Antiplatelet therapy
Postprocedural bleeding
.20
IPB, Intraprocedural bleeding; TA, tubular adenoma; TVA, tubulovillous adenoma; SSA, sessile serrated adenoma; TSA, traditional serrated adenoma. Values shown are number (%) unless otherwise indicated.
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Figure 1. A, A 40-mm Paris IIa þ Is nongranular lesion is seen on the anterior wall of the cecum after submucosal injection. B, A large submucosal vessel that has been partially excised tangentially along its longitudinal axis can be seen. C, B with tram track (white dashed lines) outlining the bleeding vessel that has been transected longitudinally can be discerned. D, The bleeding was refractory to snare tip soft coagulation and was thus clipped. One clip was sufficient to achieve hemostasis for this large vessel; however, subsequent resection of residual adenoma was difficult. E, A transected vessel that is not yet bleeding can be seen in the EMR defect (blue arrow). The other end of the vessel is seen on the underside of the resected specimen (red arrow). F, The vessel identified in E is now bleeding (blue arrow). G, This vessel has been effectively treated with snare tip soft coagulation (blue arrow). H, The final EMR defect displays clean margins with no residual adenoma and no bleeding. Two separate sites of bleeding required different modalities for effective hemostasis (snare tip soft coagulation (blue arrow) and clip). The patient was well after the procedure and was able to be discharged the same day.
Figure 2. A, Rectal 60-mm Paris IIa þ Is mixed granular and nongranular lesion is seen after submucosal injection. B, EMR results in multifocal intraprocedural bleeding. C, A bleeding site has been identified. The bleeding spreads out in a fan shape with the apex at the bleeding point (blue arrow). In brisk bleeding, this is a useful way to localize the bleeding source. D, Water jet irrigation may cause sufficient submucosal edema to stop or slow the bleeding by tamponade. E, The bleeding vessel has been successfully treated with snare tip soft coagulation (blue arrow). An artery approximately 2 mm in diameter can be visualized entering the EMR defect at the 12 o’clock position and running as a white band in the submucosal plane (black arrows). F, The postresection defect is hemicircumferential and shows various areas of snare tip soft coagulation. Patient was well after the procedure and was able to be discharged the same day.
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REFERENCES 1. Bourke M. Current status of colonic endoscopic mucosal resection in the west and the interface with endoscopic submucosal dissection. Dig Endosc 2009;21(Suppl 1):S22-7. 2. Moss A, Bourke MJ, Williams SJ, et al. Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia. Gastroenterology 2011;140:1909-18. 3. Swan MP, Bourke MJ, Alexander S, et al. Large refractory colonic polyps: is it time to change our practice? A prospective study of the clinical and economic impact of a tertiary referral colonic mucosal resection and polypectomy service (with videos). Gastrointest Endosc 2009;70:1128-36. 4. Anderson MA, Ben-Menachem T, Gan SI, et al. Management of antithrombotic agents for endoscopic procedures. Gastrointest Endosc 2009;70:1060-70. 5. Bourke M. Endoscopic mucosal resection in the colon: a practical guide. Techn Gastrointest Endosc 2011;13:35-49. 6. Holt BA, Bourke MJ. Wide field endoscopic resection for advanced colonic mucosal neoplasia: current status and future directions. Clin Gastroenterol Hepatol 2012;10:969-79. 7. Moss A, Bourke MJ, Metz AJ. A randomized, double-blind trial of succinylated gelatin submucosal injection for endoscopic resection of large sessile polyps of the colon. Am J Gastroenterol 2010;105:2375-82.
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8. Chan A. Biomedical device technology: principles and design. Springfield (Ill): Charles C Thomas; 2008. 9. Ginsberg GG, Kochman ML, Norton ID, Gostout CJ, editors. Clinical gastrointestinal endoscopy. 2nd ed. Philadelphia (Pa): Elsevier; 2011. 10. Slivka A, Bosco JJ, Barkun AN, et al. Electrosurgical generators: MAY 2003. Gastrointest Endosc 2003;58:656-60. 11. ERBE Elektromedizin. Principles of electrosurgery. http://www.erbemed.com/erbe/media/Marketingmaterialien/85800-131_ERBE_EN_ Application_brochure_of_gastroenterology__D064045.pdf. Accessed November 12, 2012. 12. Swan MP, Bourke MJ, Moss A, et al. The target sign: an endoscopic marker for the resection of the muscularis propria and potential perforation during colonic endoscopic mucosal resection. Gastrointest Endosc 2011;73:79-85. 13. Kim HS, Kim TI, Kim WH, et al. Risk factors for immediate postpolypectomy bleeding of the colon: a multicenter study. Am J Gastroenterol 2006;101:1333-41. 14. von Delius S, Thies P, Umgelter A, et al. Hemodynamics after endoscopic submucosal injection of epinephrine in patients with nonvariceal upper gastrointestinal bleeding: a matter of concern. Endoscopy 2006;38:1284-8. 15. Morris ML, Tucker RD, Baron TH, et al. Electrosurgery in gastrointestinal endoscopy: principles to practice. Am J Gastroenterol 2009;104: 1563-74.
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APPENDIX – ELECTROPHYSIOLOGICAL EQUATIONS Ohm’s Law
V[IxR Voltage is equal to the product of current and resistance
Power
P[VxI Power is equal to the product of voltage and current
Energy
E[Pxt Energy is equal to the product of power and time
Current density
J[I/A Current density is equal to the amount of current passing through a given unit area
Joule’s Law
Q [ I2 x R x t The amount of heat generated is equal to the product of the square of current and resistance (per unit time)
163.e1 GASTROINTESTINAL ENDOSCOPY Volume 78, No. 1 : 2013
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Background: Wide-field EMR (WF-EMR) of large colonic lesions exposes submucosal vessels, which may result in intraprocedural bleeding (IPB). Ongoing bleeding may obscure the endoscopic field, prolonging the procedure and reducing safety and accuracy. A number of potential interventions to control bleeding exist; however, they have inherent limitations. Safe, readily applicable, inexpensive, and effective therapy to control EMR-IPB has not yet been described. Objective: To evaluate the safety and efficacy of the snare tip soft coagulation (STSC) technique to control IPB after WF-EMR of large colonic lesions. Design: Single-center, prospective cohort study. Setting: Tertiary care referral center. Patients: A total of 196 patients undergoing wide-field colonic EMR for flat and sessile lesions 20 mm or larger. Interventions: A standard inject-and-resect EMR technique was applied. IPB was defined as bleeding obscuring the endoscopic field that persisted for 60 seconds or longer. STSC was performed by using the tip of the polypectomy snare to apply soft coagulation (80 W) to sites of IPB. Main Outcome Measurements: Immediate hemostasis, postprocedural bleeding, and other adverse events. Results: A total of 198 lesions (mean size 41.5 mm, 64% in the right colon) were removed in 196 patients (mean age 68 years, 52.5% male). STSC alone achieved effective hemostasis in 40 of 44 cases of IPB (91%). In the remaining 4 cases, additional treatment with coagulating forceps or clips was required to achieve hemostasis. There were no immediate STSC-related adverse events. There was no statistically significant difference between the IPB and non-IPB groups in relation to the use of antiplatelet (P Z .2) or anticoagulation agents (P Z .4), postprocedural bleeding (P Z .8) and adverse event rates (P Z .7). Limitations: Nonrandomized study. Conclusions: STSC is a simple and efficient first-line technique for achieving hemostasis of IPB during WF-EMR in the colon. It succeeds in the majority of cases and appears to be safe.
Abbreviations: AMN, advanced mucosal neoplasia; EMR-IPB, EMRrelated intraprocedural bleeding; IPB, intraprocedural bleeding; STSC, snare tip soft coagulation; WF-EMR, wide-field EMR.
Copyright ª 2013 by the American Society for Gastrointestinal Endoscopy 0016-5107/$36.00 http://dx.doi.org/10.1016/j.gie.2013.02.030
DISCLOSURE: The authors disclosed no financial relationships relevant to this publication.
Received December 15, 2012. Accepted February 20, 2013.
Use your mobile device to scan this QR code and watch the author interview. Download a free QR code scanner by searching “QR Scanner” in your mobile device’s app store. 158 GASTROINTESTINAL ENDOSCOPY Volume 78, No. 1 : 2013
Current affiliations: Department of Gastroenterology and Hepatology, Westmead Hospital, Westmead, Sydney, New South Wales, Australia. Reprint requests: Michael J. Bourke, MBBS, FRACP, Department of Gastroenterology and Hepatology, Westmead Hospital, Westmead, Sydney, NSW 2145, Australia. If you would like to chat with an author of this article, you may contact Dr Bourke at [email protected].
www.giejournal.org
Fahrtash-Bahin et al
Wide-field EMR (WF-EMR) is a safe, cost-effective, and clinically efficacious therapy for advanced mucosal neoplasia (AMN) (large sessile polyps and laterally spreading tumors O20 mm) of the colon.1-3 This type of endoscopic therapy results in a mucosal defect of at least 20 mm and as large as 100 mm and occupying between one fourth of and the entire circumference of the bowel wall. Consequently, there are often numerous exposed submucosal vessels that may be transected or injured during the EMR procedure and result in intraprocedural bleeding (IPB) (which may arise from within or at the margin of the defect). EMR-related IPB (EMR-IPB) is predominantly nonspurting. Bleeding may be self-limited, but is not always so and often obscures the endoscopic field, prolonging the procedure and reducing safety and accuracy. A number of potential interventions to control bleeding exist. These include injection of epinephrine, forceps, or argon plasma electrocoagulation and endoscopic clipping. They all have inherent limitations. Our hypothesis is that snare tip soft coagulation (STSC) is a highly effective, safe, and readily applicable technique for the control of EMR-IPB.
METHODS Between January 2011 and September 2012, a subgroup of patients referred for WF-EMR of AMN consented to participate in this observational cohort study. The study was approved by the hospital research ethics committee (SAC2010/5/4.9(3155) AU RED HREC/10/WMEAD/103). Patients were asked to withhold antiplatelet agents 7 days before the procedure. Anticoagulants were managed in accordance with current American Society for Gastrointestinal Endoscopy guidelines.4 Two senior endoscopists (MJB, SJW) with extensive EMR experience or 2 senior fellows under their direct supervision performed all procedures by using a standardized inject-and-resect technique and a microprocessor-controlled electrosurgical generator (VIO 300D; ERBE Elektromedizin, Tübingen, Germany).2,5,6 The submucosal injectate composed of succinylated gelatin (Gelofusine; B. Braun Australia Pty Ltd, Bella Vista, Australia) with indigo carmine blue (80 mg/ 500 mL solution) and 1:10,000 epinephrine (1 mL/10-mL injection).7 EMR-IPB was defined as oozing or spurting of blood persisting for longer than 60 seconds and not responding to water jet irrigation. The primary endpoint was effective hemostasis, defined as complete cessation of bleeding. Secondary endpoints included clinically significant postprocedural bleeding (defined as occurring at any time within 2 weeks after the procedure and requiring hospital admission) and immediate and delayed adverse events. Statistical analysis was performed by using SPSS software version 20 (IBM, Chicago, Ill). The Mann-Whitney U test was applied for comparison of continuous variables, and the c2 or Fisher exact test was used for comparing www.giejournal.org
Snare tip soft coagulation
Take-home Message Intraprocedural bleeding during EMR of large colonic lesions obscures the endoscopic view and may compromise the accuracy and safety of the procedure. Soft coagulation through a snare tip is a readily available, effective, and safe hemostatic modality for intraprocedural bleeding.
dichotomous variables. A 2-tailed P value of !.05 was considered significant. Two patients had 2 colonic lesions undergoing resection, and 1 lesion was selected at random for the purpose of analysis.
Electrophysiological principles During STSC, electrical energy from the snare tip is converted to thermal energy, which leads to tissue desiccation and vessel coagulation. The amount of heat transferred to each point in the tissue (per unit of time) is given by the product of the square of the current density and resistance. Current density refers to the amount of current passing through a given unit area.8,9 Peak voltage output for the SOFT COAG mode is capped at 190 V in the ERBE VIO system.10,11 Ohm’s law states that current is equal to the quotient of voltage and resistance. As the tissue is desiccated, the resistance to current increases exponentially within a fraction of a second, and because voltage is fixed, theoretically current can no longer flow. In practice, once the tissue is coagulated, further applications of STSC do not result in any endoscopically appreciable tissue effect. This is a theoretical key built-in safety mechanism of the SOFT COAG mode. Basically, effective tissue desiccation terminates energy transfer and limits any further tissue injury. In contrast, with traditional coagulation modes with higher peak voltages, current may be forced through already desiccated tissue, leading to deep thermal injury. (See Appendix, available online at www. giejournal.org.)
Technique STSC has been increasingly used in our department to control IPB for the past 4 years. In this study, it was performed as demonstrated in Videos 1 and 2 (available online at www.giejournal.org). Monopolar SOFT COAG at 80 W Effect 4 was used (VIO 300D; ERBE Elektromedizin). The snare tip is positioned 1 to 2 mm beyond the end of the snare sheath. The wire tip is applied directly and gently (it is a contact technique) to the bleeding point and the (blue) diathermy pedal depressed for 1 to 2 seconds. This results in energy transfer and coagulation of the vessel. The ERBE device limits voltage output to less than 190 V. Snares were either 20 mm spiral (wire diameter 0.48 mm; Olympus Corporation, Tokyo, Japan) or 30 15-mm mini-snare (wire diameter 0.3 mm; Cook Medical, Browns Plains, Volume 78, No. 1 : 2013 GASTROINTESTINAL ENDOSCOPY 159
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Australia). The number of snare tip coagulations was at the discretion of the endoscopist. It can be repeated as many as 5 times to achieve hemostasis. If bleeding persists, additional applications beyond this number are unlikely to succeed.
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Intraprocedural hemostasis is a highly relevant, yet underdocumented aspect of advanced endoscopic resection. In our cohort, IPB developed in 24% of patients undergoing WF-EMR for colonic AMN. Kim et al13 reported an immediate postpolypectomy bleeding (IPPB) rate of 2.8% in a cross-sectional study of an unselected cohort of 9336 polypectomies for colonic lesions larger than 4 mm. On multivariate analysis, polyp size greater than 10 mm, age 65 years and older, laterally spreading
tumors, or pedunculated morphology and use of blended current and anticoagulants were some of the factors associated with IPPB. The mean size of lesions in the IPPB group was 13.2 mm compared with 50.9 mm in our cohort of IPB. Effective control of EMR-IPB maintains clear endoscopic visualization and may improve procedure time and safety. The modern endoscopist has a broad range of potential hemostatic therapies, including epinephrine injection, endoscopic clips, and argon plasma and forceps coagulation. Epinephrine is already a component of injection solutions in many centers. Further injection of epinephrine around bleeding vessels is often not effective and may lead to tissue ischemia locally or systemic cardiovascular sequelae.14 Placement of clips intraprocedurally may impair completion of EMR, especially if the bleeding involves a site with remaining pathology. Furthermore, clips may not be the ideal hemostatic technique for small bleeding vessels because of insufficient compression of the target vessel. The colon, especially in a proximal location, is relatively thin and susceptible to deep injury or even perforation as a result of excessive deep thermal injury from forceps or argon plasma electrocoagulation. There is also additional procedure time (related to device exchange) and expense associated with the use of these modalities. In our cohort of 47 patients, immediate hemostatic control with STSC monotherapy was achieved in 91% of lesions without adverse events. Although we use STSC as first-line therapy, even in brisk bleeding, in 3 patients (6.4%) with brisk pulsatile bleeding, coagulating forceps alone were used for hemostasis. The safety of STSC is underpinned by the electrophysiological principles outlined previously. Because peak voltage is fixed, tissue resistance increases swiftly once desiccation of the target tissue is achieved, halting or severely attenuating further energy transfer and thus minimizing the risk of deep thermal injury.15 STSC is furthermore a very cost- and timeeffective technique using the polypectomy snare for hemostasis as well as resection. It is important to note that this feature does not apply to conventional or forced coagulation in which the maximum voltage is not capped and the risk of deep tissue injury is always present. We acknowledge some limitations of this study, including the lack of randomization and procedures being performed at a single academic tertiary center. Furthermore, the endoscopist needs a dedicated electrosurgical unit that has soft coagulation capabilities. In conclusion, STSC is a readily available, highly effective, and economically sound technique for the management of EMR-IPB. There are multiple benefits, including the absence of device exchange, resulting in decreased procedure time and no added cost. The technique is simple to use, rapidly used, and highly efficient. We believe STSC to be a valuable addition to the current options for EMR-IPB and possibly the best first-line therapy.
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RESULTS A total of 198 lesions were removed in 196 patients (Table 1). The mean age was 68.0 years and 52.6% of patients were male. The mean lesion size was 41.5 mm (range 20-120 mm). Of the patients, 54.1% had lesions located in the right colon. Twenty-five (12.8%) and 6 (3.1%) patients were receiving antiplatelet and warfarin therapy, respectively. The mean time of cessation of aspirin, clopidogrel, and warfarin was 5, 6.5, and 4.3 days, respectively. Forty-seven patients (24.0%) had IPB. The bleeding was at the mucosal incision edge in 17 lesions (36.2%), within the defect in 28 lesions (60.0%), and at both sites in 2 lesions (4.3%). On multivariate analysis, larger lesion size predicted IPB (P Z .01). Hemostasis was achieved in 40 of 44 cases (90.9%) of IPB by using STSC alone. In the remaining 4 cases, alternative or additional therapy was required for hemostasis. In 2 cases each, either clips or coagulating forceps were required in addition to STSC. In 3 cases of brisk pulsatile bleeding, coagulating forceps alone were used (Figs. 1 and 2, Videos 1 and 2). EMR was completed in all 47 lesions. No adverse events occurred related to STSC (Table 1). The postprocedural bleeding rate and adverse events in the IPB group treated with STSC were not statistically different from those in the non-IPB group. Specifically, 1 intraprocedural perforation occurred in the non-IPB group compared with none in the IPB group (P Z .73). This was attributed to muscularis propria resection. A muscularis propria defect (evidenced by the target sign12) occurred in 3 IPB cases compared with 5 non-IPB cases (P Z .07). These patients were managed intraprocedurally with clips and had no significant adverse outcomes. The site of IPB (ie, at the edge or within the resection defect) did not influence the response to treatment, nor was it associated with adverse events, including postprocedural bleeding and perforation.
DISCUSSION
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TABLE 1. Characteristics of patients, lesions, and periprocedural compilations Total (N [ 196)
IPB (n [ 47)
No IPB (n [ 149)
P value
68.0 (22-93)
66.4 (42-88)
68.5 (22-93)
.29
103 (52.6)
24 (51.1)
79 (53.0)
.82
93 (47.4)
23 (48.9)
70 (47.0)
41.5 (20-120)
50.9 (20-120)
38.6 (20-100)
.01
Left side of the colon
90 (45.9)
24 (51.1)
57 (38.3)
.07
Right side of the colon
106 (54.1)
23 (48.9)
92 (61.7)
0-IIaþIs
62 (31.6)
25 (53.2)
37 (24.8)
0-Is
17 (8.7)
4 (8.5)
13 (8.7)
0-IIa
91 (46.4)
12 (25.5)
79 (53.0)
0-IIb
11 (5.6)
2 (4.3)
10 (6.7)
0-IIaþIIb
3 (1.5)
0
3 (2.0)
0-IIc or 0-IIaþc
3 (1.5)
4 (8.5)
7 (4.7)
116 (59.2)
29 (61.7)
86 (57.7)
Nongranular
65 (33.2)
15 (31.9)
50 (33.6)
Mixed
14 (7.1)
3 (6.4)
11 (7.4)
1 (0.5)
0
1 (0.7)
TA
44 (22.4)
6 (12.8)
38 (25.5)
TVA
103 (52.6)
33 (70.2)
70 (47.0)
SSA
22 (11.2)
2 (4.2)
20 (13.4)
TSA
3 (1.5)
0
3 (2.0)
15 (7.7)
4 (8.5)
11 (7.4)
9 (4.6)
2 (4.3)
7 (4.7)
Total
25 (12.8)
6 (12.8)
19 (12.6)
Aspirin
16 (8.2)
4 (8.5)
12 (7.9)
Clopidogrel
8 (4.1)
2 (4.2)
6 (4.0)
Dual
1 (0.5)
0
1 (0.7)
Warfarin
6 (3.1)
2 (4.3)
4 (2.0)
.41
Muscularis propria defect
8 (4.1)
3 (8.5)
5 (3.4)
.07
Free perforation
1 (0.5)
0
1 (0.7)
.73
11 (5.6)
2 (4.3)
9 (6.0)
.79
Age (range), y Sex Male Female Mean lesion size, mm Location
Paris classification .01
Morphology Granular
Unclassifiable
.93
Final histology
Carcinoma Mixed
.19
Antiplatelet therapy
Postprocedural bleeding
.20
IPB, Intraprocedural bleeding; TA, tubular adenoma; TVA, tubulovillous adenoma; SSA, sessile serrated adenoma; TSA, traditional serrated adenoma. Values shown are number (%) unless otherwise indicated.
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Figure 1. A, A 40-mm Paris IIa þ Is nongranular lesion is seen on the anterior wall of the cecum after submucosal injection. B, A large submucosal vessel that has been partially excised tangentially along its longitudinal axis can be seen. C, B with tram track (white dashed lines) outlining the bleeding vessel that has been transected longitudinally can be discerned. D, The bleeding was refractory to snare tip soft coagulation and was thus clipped. One clip was sufficient to achieve hemostasis for this large vessel; however, subsequent resection of residual adenoma was difficult. E, A transected vessel that is not yet bleeding can be seen in the EMR defect (blue arrow). The other end of the vessel is seen on the underside of the resected specimen (red arrow). F, The vessel identified in E is now bleeding (blue arrow). G, This vessel has been effectively treated with snare tip soft coagulation (blue arrow). H, The final EMR defect displays clean margins with no residual adenoma and no bleeding. Two separate sites of bleeding required different modalities for effective hemostasis (snare tip soft coagulation (blue arrow) and clip). The patient was well after the procedure and was able to be discharged the same day.
Figure 2. A, Rectal 60-mm Paris IIa þ Is mixed granular and nongranular lesion is seen after submucosal injection. B, EMR results in multifocal intraprocedural bleeding. C, A bleeding site has been identified. The bleeding spreads out in a fan shape with the apex at the bleeding point (blue arrow). In brisk bleeding, this is a useful way to localize the bleeding source. D, Water jet irrigation may cause sufficient submucosal edema to stop or slow the bleeding by tamponade. E, The bleeding vessel has been successfully treated with snare tip soft coagulation (blue arrow). An artery approximately 2 mm in diameter can be visualized entering the EMR defect at the 12 o’clock position and running as a white band in the submucosal plane (black arrows). F, The postresection defect is hemicircumferential and shows various areas of snare tip soft coagulation. Patient was well after the procedure and was able to be discharged the same day.
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REFERENCES 1. Bourke M. Current status of colonic endoscopic mucosal resection in the west and the interface with endoscopic submucosal dissection. Dig Endosc 2009;21(Suppl 1):S22-7. 2. Moss A, Bourke MJ, Williams SJ, et al. Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia. Gastroenterology 2011;140:1909-18. 3. Swan MP, Bourke MJ, Alexander S, et al. Large refractory colonic polyps: is it time to change our practice? A prospective study of the clinical and economic impact of a tertiary referral colonic mucosal resection and polypectomy service (with videos). Gastrointest Endosc 2009;70:1128-36. 4. Anderson MA, Ben-Menachem T, Gan SI, et al. Management of antithrombotic agents for endoscopic procedures. Gastrointest Endosc 2009;70:1060-70. 5. Bourke M. Endoscopic mucosal resection in the colon: a practical guide. Techn Gastrointest Endosc 2011;13:35-49. 6. Holt BA, Bourke MJ. Wide field endoscopic resection for advanced colonic mucosal neoplasia: current status and future directions. Clin Gastroenterol Hepatol 2012;10:969-79. 7. Moss A, Bourke MJ, Metz AJ. A randomized, double-blind trial of succinylated gelatin submucosal injection for endoscopic resection of large sessile polyps of the colon. Am J Gastroenterol 2010;105:2375-82.
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8. Chan A. Biomedical device technology: principles and design. Springfield (Ill): Charles C Thomas; 2008. 9. Ginsberg GG, Kochman ML, Norton ID, Gostout CJ, editors. Clinical gastrointestinal endoscopy. 2nd ed. Philadelphia (Pa): Elsevier; 2011. 10. Slivka A, Bosco JJ, Barkun AN, et al. Electrosurgical generators: MAY 2003. Gastrointest Endosc 2003;58:656-60. 11. ERBE Elektromedizin. Principles of electrosurgery. http://www.erbemed.com/erbe/media/Marketingmaterialien/85800-131_ERBE_EN_ Application_brochure_of_gastroenterology__D064045.pdf. Accessed November 12, 2012. 12. Swan MP, Bourke MJ, Moss A, et al. The target sign: an endoscopic marker for the resection of the muscularis propria and potential perforation during colonic endoscopic mucosal resection. Gastrointest Endosc 2011;73:79-85. 13. Kim HS, Kim TI, Kim WH, et al. Risk factors for immediate postpolypectomy bleeding of the colon: a multicenter study. Am J Gastroenterol 2006;101:1333-41. 14. von Delius S, Thies P, Umgelter A, et al. Hemodynamics after endoscopic submucosal injection of epinephrine in patients with nonvariceal upper gastrointestinal bleeding: a matter of concern. Endoscopy 2006;38:1284-8. 15. Morris ML, Tucker RD, Baron TH, et al. Electrosurgery in gastrointestinal endoscopy: principles to practice. Am J Gastroenterol 2009;104: 1563-74.
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APPENDIX – ELECTROPHYSIOLOGICAL EQUATIONS Ohm’s Law
V[IxR Voltage is equal to the product of current and resistance
Power
P[VxI Power is equal to the product of voltage and current
Energy
E[Pxt Energy is equal to the product of power and time
Current density
J[I/A Current density is equal to the amount of current passing through a given unit area
Joule’s Law
Q [ I2 x R x t The amount of heat generated is equal to the product of the square of current and resistance (per unit time)
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