The incidence of "silent" free air and aspiration pneumonia detected by CT after gastric endoscopic submucosal dissection

Background: Although endoscopic submucosal dissection (ESD) is feasible as a treatment for early gastric cancer, it requires great skill to perform and may place patients at increased risk of a number of complications, including perforation and aspiration pneumonia. Objective: To investigate the incidence of "silent" free air without endoscopic perforation and aspiration pneumonia detected by CT after ESD and risk factors for the development of these 2 conditions. Design: Prospective cohort study. Setting: Single academic center. Patients: This study involved 87 patients with a total of 91 malignancies. Intervention: All patients underwent chest and abdominal CT and blood biochemistry analysis before and 1 day after ESD. Main Outcome Measurements: The incidence of silent free air and aspiration pneumonia after ESD and the related risk factors. Results: Silent free air was identified in 37.3% of patients without perforation. Tumor location (the upper portion of the stomach), the presence of a damaged muscular layer during ESD, and procedure time, but not specimen size, were significantly associated with silent free air (P = .006, P = .04, P = .02, and P = .53, respectively). According to the receiver-operating characteristic analysis, the resulting cutoff value of the procedure time for silent free air was 105 minutes (67.7% sensitivity, 65.4% specificity). Only procedure time (>= 105 minutes) was an independent predictor of silent free air development (odds ratio 3.23; 95% confidence interval, 1.21-8.64; P = .02). On the other hand, aspiration pneumonia was seen in 6.6% of patients. Silent free air and aspiration pneumonia did not affect hospitalization. Limitations: Single center and small number of patients. Conclusions: Silent free air is frequently observed after ESD, and longer procedure time (>= 105 minutes) was an independent risk factor for silent free air. However, silent free air and aspiration pneumonia detected by CT are not associated with clinically significant complications. (Gastrointest Endosc 2012;76:1116-23.)