Procedure

The operative distance is 2-10 mm; at a greater distance, electrical discharge disappears. Energy passes through the body and is returned by a neutral electrode placed on the skin. The argon gas flow blows blood and debris away from the coagulation site, improving visualization. The white-blue arc of light allows targeted and controlled energy application. Coagulation vapor should be continuously suctioned (Fig. 20.6). Penetration depth of coagulation is 0.8-3 mm, depending on duration and intensity of energy application. After one second of application, penetration depth is around 2 mm; after five seconds, depth of penetration is around 3 mm. In experiments on swine gastric mu cosa, at five seconds of application at all power settings (40100 W) coagulation remained limited to the mucosa; even at 20 seconds and a power setting of 40 W there was no coagulation effect beyond the mucosa (25). The duration of each individual pulse for clinical use, especially in the colon, should be between 0.5 and two seconds maximum. Depth of penetration is automatically limited by the desiccated tissue layers, which prevent the spread of thermal and electrical energy (29) (Fig. 20.7). Nonetheless, APC application should be used with the utmost caution around the particularly thin-walled cecum, in order to avoid perforation (Fig. 20.8). Though valid figures on perforation rates are lacking they are likely well below 1 %.

Fig. 20.6 Device for suctioning vapor produced during APC or laser application.

MhP B

Fig. 20.8 Perforation from APC application in duodenum. The perforation site is marked with an arrow.

Fig. 20.6 Device for suctioning vapor produced during APC or laser application.

MhP B

Fig. 20.8 Perforation from APC application in duodenum. The perforation site is marked with an arrow.

Applicator

Isolating layer of vapor

Dispersion of the plasma jet

Neutral electrode

Neutral electrode

— Desiccation zone

-Coagulation zone

-Devitalization zone

Fig. 20.7 Depth of devitalization and coagulation zones, schematic illustration. The evaporating liquid forms a cloud of vapor. Longer-lasting application causes formation of a spongelike dry structure (F) on the surface of parenchymatous organs. The electrically isolating vapor cloud and the formation of a desiccation zone together cause the plasma beam to automatically move over the entire reachable surface (based on 10).

— Desiccation zone

-Coagulation zone

-Devitalization zone

Fig. 20.7 Depth of devitalization and coagulation zones, schematic illustration. The evaporating liquid forms a cloud of vapor. Longer-lasting application causes formation of a spongelike dry structure (F) on the surface of parenchymatous organs. The electrically isolating vapor cloud and the formation of a desiccation zone together cause the plasma beam to automatically move over the entire reachable surface (based on 10).

One drawback to APC is bowel distention caused by argon gas insufflation. This problem can be minimized by reducing the amount of gas flow to below one liter per minute and by intermittent suctioning. Contact between the probe tip and colon wall should be avoided during coagulation as it can force argon gas into the tissue, potentially causing submucosal emphysema.

Complications and potential applications. Even without perforation, argon gas can permeate the colon wall. Occurrence of pneumoperitoneum and pneumomediastinum has been reported. Clinical way of acting is problematic and in such situations excluding perforation is nearly—if not entirely—impossible.

Argon plasma coagulation techniques can be applied in the colon for achieving hemostasis in bleeding angiodysplasias ( S 20.1), diverticular hemorrhage, postpolypectomy rebleeding (Fig. 20.9), and tumor bleeding.

Fig. 20.9 APC application (Erbe) in rebleeding after polypectomy. b Hemorrhage from the polypectomy wound.

a Shortstalked rectal polyp. c Coagulation at the resection site achieves hemostasis.

Fig. 20.9 APC application (Erbe) in rebleeding after polypectomy. b Hemorrhage from the polypectomy wound.

a Shortstalked rectal polyp. c Coagulation at the resection site achieves hemostasis.

|T| 20.1 Coagulation of an angiodysplasia using APC (ERBE)

|T| 20.1 Coagulation of an angiodysplasia using APC (ERBE)

abc a-d Coagulation of an angiodysplasia (a) in the ascending colon. The probe is extended from the endoscope's working channel to 2-10 mm from the tissue (b). Energy application: tissue blanching is a sign of successful coagulation (c). After coagulation the angiodysplasia is no longer visible (d).

abc a-d Coagulation of an angiodysplasia (a) in the ascending colon. The probe is extended from the endoscope's working channel to 2-10 mm from the tissue (b). Energy application: tissue blanching is a sign of successful coagulation (c). After coagulation the angiodysplasia is no longer visible (d).

Colon Probe

e-i Coagulation of an angiodysplasia (e) in the ascending colon. Energy application. Starting at the periphery, the vascular malformation is destroyed using brief pulses to effect coagulation (f-h). The bluish beam is easily visible at the probe tip (h). After coagulation the angiodysplasia is no longer visible (i).

e-i Coagulation of an angiodysplasia (e) in the ascending colon. Energy application. Starting at the periphery, the vascular malformation is destroyed using brief pulses to effect coagulation (f-h). The bluish beam is easily visible at the probe tip (h). After coagulation the angiodysplasia is no longer visible (i).

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