Purpose or Case Report: Administering oral contrast less than two hours before sedation/anesthesia is often needed for computed tomography (CT) studies of the abdomen in children, but violates the American Society of Anesthesiologists (ASA) nothing-by-mouth guidelines and may increase the risk of aspiration pneumonia. ASA guidelines are based on gastric aspiration. Oral contrast is best administered 1 hour prior to imaging for optimal abdominal CT evaluation. The aim of our study was to measure residual gastric fluid volume (RGV) by CT and with manual aspiration in subjects undergoing general anesthesia (GA) less than 2 hours after oral contrast.
Methods & Materials: Institutional review board approval was obtained. 71 subjects were enrolled in the study. Subject were given oral contrast 1 hour prior to GA, the CT was performed and gastric aspiration by anesthesia using a Salem Sump™ enteric tube using a BARD™ Toomey Catheter Tip Syringe, sequentially positioning the patient in supine, left and right lateral decubitus position and recording the volume and pH. Two observers measure the RGV by semi-manual segmentation while viewing the stomach contents in the 3 orthogonal planes using Vitrea® fx (Vital Images, Minnetonka MN, USA).
Results: 66 subjects completed the study, mean age was 2.7 years (1.59), mean weight was 13.4 kg (+/-3.96). Time from end of contrast to GA/CT was 92 minutes with a range of 63 to 134 minutes. Measurement of RGV by CT yielded a median of 13.6 ml (3.1 to 33.2 ml interquartile range). Aspiration of gastric contents yielded a median of 6 (0 to 110) ml of fluid (20 subjects had 0 ml aspirated). 17% met the ASA fasting guideline; 47% met the guideline by aspiration and 32% met guideline by CT volume. However, of the 17% that met the fasting requirement, 8/11 still violated the guideline by volume. Subjects with 0 ml aspirated: 9 violated the > 0.4 ml/kg RGV. Airway was secured by endotracheal tube in 52, laryngeal mask airway in 4 and one had a tracheostomy. 10 were managed without an artificial airway.
Conclusions: (1) Our current practice of a 1 hour preparation for GA results in 68% of subjects having > 0.4 ml/kg of enteric contrast in the stomach supports the continued practice of airway protection with a cuffed endotracheal tube. (2) CT and gastric aspiration results are often discordant. CT or MRI may be a superior method of measuring the residual gastric contents.