Radiofrequency energy ablation of Barrett's esophagus: the best is yet to come!

How good is the neosquamous epithelium?

BACKGROUND/AIMS

Endoscopic radiofrequency ablation of dysplastic Barrett's esophagus (BE) combined with proton pump inhibitor therapy is commonly utilized for preventing progression of dysplastic BE to esophageal adenocarcinoma. Fundamental to the success of this and all ablative approaches is the healing of the ablated areas of BE with a stratified squamous epithelium referred to as 'neosquamous epithelium' (NSE). Although NSE appears 'normal' endoscopically, the reemergence of BE over time in the previously ablated segments raises the question of the health and integrity of NSE.

METHODS

The health of NSE was recently investigated in endoscopic biopsies in vitro in a group of patients after ablation while on proton pump inhibitors. Biopsies of NSE were compared to upper squamous epithelium (USE) from the same patients morphologically (light microscopy) and with respect to barrier function by measuring electrical resistance and fluorescein flux in mini-Ussing chambers.

RESULTS

Compared to USE, NSE exhibited dilated intercellular spaces and inflammation and defective barrier function by low electrical resistance and high fluorescein flux. Moreover, NSE exhibited downregulation of claudin-4, a highly expressed protein in squamous tight junctions.

CONCLUSION

NSE has defective barrier function in part due to downregulation of claudin-4. Since downregulation of claudin-4 increases paracellular permeability to cations, e.g. hydrogen ions, NSE is more vulnerable to attack and damage by acidic and weakly acidic refluxates--a phenomenon that may contribute in part to the reemergence of BE.

Anesthesiology and gastroenterology

A successful population-based colorectal cancer screening requires efficient colonoscopy practices that incorporate high throughput, safety, and patient satisfaction. There are several different modalities of nonanesthesiologist-administered sedation currently available and in development that may fulfill these requirements. Modern-day gastroenterology endoscopic procedures are complex and demand the full attention of the attending gastroenterologist and the complete cooperation of the patient. Many of these procedures will also require the anesthesiologist's knowledge, skills, abilities, and experience to ensure optimal procedure results and good patient outcomes. The goal of this review is (1) to provide a gastroenterology perspective on the use of propofol in gastroenterology endoscopic practice, and (2) to describe newer GI endoscopy procedures that gastroenterologists perform that might involve anesthesiologists.