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.