Technological Review

Clinical applications of the argon plasma coagulator

Adjunctive therapy after piecemeal resection of colonic polyps

In a case–control study, Zlatanic et al.⁸ reviewed the course of 77 patients with large sessile polyps (>2 cm) who had undergone piecemeal polypectomy with and without APC. Thirty patients received APC therapy (40 W, 0.8 L/min flow rate) to residual adenomatous tissue. Historical comparison groups included 32 patients without residual polyp after piecemeal excision, and 10 patients with residual polyp tissue. The APC group exhibited a 6-month recurrence rate that was the same as in patients who

Radiation proctopathy

Many case series have been published on the use of APC in the treatment of radiation-induced proctopathy.10., 11., 12., 13., 14., 15., 16., 17. Power settings vary from 40 to 60 W, with gas flows from 1 to 1.5 L/ min. (Table 2). The majority of patients achieved symptomatic improvement after approximately two treatment sessions. The number of treatment sessions has been found to significantly correlate with the extent of the proctopathy.¹⁶ Relief from transfusion dependency was seen in 34 of 35

Vascular lesions

Watermelon stomach or gastric antral vascular ectasia (GAVE) is an uncommon source of GI blood loss, which typically presents with an iron deficiency anemia. Non-comparative studies have demonstrated efficacy of APC in the treatment of watermelon stomach by using variable power settings (40–100 W) and acid suppressive regimens (Fig. 1).18., 19., 20. EUS suggests that there is thickening of the second and third echo layers in GAVE that are associated with hypoechoic tubular structures.

Ablation of Barrett's esophagus

Controversy surrounds endoscopic ablative therapy for Barrett's epithelium. The possibility of residual nests of metaplastic cells underneath the layer of neosquamous epithelium remains a concern. As in other ablative modalities, variables to consider in the treatment of Barrett's esophagus include:

• Length of the Barrett's segment

• Acid suppressive regimen—dosage and documentation of success

• APC settings

• Treatment pattern

• Post-treatment surveillance

Ten case series, totaling 304 patients, are

Treatment of bleeding peptic ulcers and the prevention of recurrent esophageal varices

In a small randomized controlled trial, the APC was compared with the heat probe in 41 patients presenting with peptic ulcer disease with major stigmata of recent hemorrhage, including active bleeding or a non-bleeding visible vessel.³⁷ The groups were well-matched for clinical criteria such as active bleeding and hypotension. Both APC and heat probe were similar in clinical outcomes such as initial hemostasis, recurrent bleeding, 30-day mortality, and the need for emergency surgery. It must be

Palliation of GI malignancies

The APC has been used alone or in concert with other treatment modalities in the palliation of esophageal, gastric, ampullary, and rectal malignancies. Wahab et al.¹⁸ used the APC in the palliation of various obstructing GI malignancies. In 34 patients, APC was used in concert with monopolar snare coagulation with or without radiotherapy. The majority of the patients presented with malignancies of the esophagus or gastric cardia. Savary dilation was used in some cases. A mean of 3.5 sessions

Rare uses of APC

The APC at high-power settings (80 W) has been used to shorten previously placed biliary metallic stents in treatment of stent-induced duodenal ulceration and to allow for placement of a plastic stent after occlusion.⁴³

Summary

The APC is a non-contact method of endoscopically delivered high-frequency thermal coagulation. The level of evidence and the range of APC settings in the published studies for each indication are presented in Table 4. The majority of the published clinical experience is in the realm of case series. However a few, albeit small randomized controlled trials have emerged. The APC appears most efficacious in the treatment of vascular lesions such as radiation proctopathy and GAVE. However, there is