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Updated: Jun 22, 2025
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Published on: September 22, 2023
Assessing Residual Gastric Fluid Volume after Administering Diluted Oral Contrast until One Hour Prior to Anesthesia
Suryakumar Narayanasamy1, Robert J Fleck2, Ali I Kandil1
1Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, OH 45229, USA.
Insights
Children receiving clear fluids up to one hour before anesthesia can retain significant gastric residual volume, as measured by computed tomography (CT). This finding impacts fasting protocols and pulmonary aspiration risk assessment in pediatric patients.
Area of Science:
- Pediatric Anesthesiology
- Medical Imaging
- Gastroenterology
Background:
- Gastric fluid volume is a key indicator for pulmonary aspiration risk during anesthesia.
- Current fasting protocols are evaluated based on gastric fluid volume.
- This study investigates residual gastric volume in children receiving oral contrast medium before anesthesia.
Purpose of the Study:
- To measure residual gastric fluid volume in children using a specific oral contrast medium protocol.
- To assess the safety and implications of administering clear fluids up to one hour before anesthesia in pediatric patients.
Main Methods:
- A single-center prospective observational cohort trial involving 70 children undergoing elective abdominal/pelvic CT.
- Diluted enteral contrast medium was administered starting two hours before anesthesia, ending at least one hour prior.
- Gastric fluid volume was quantified using computed tomography (CT) imaging and region of interest analysis.
Main Results:
- Median time from contrast completion to imaging was 1.5 hours.
- Computed tomography (CT) revealed significant residual gastric volumes in a majority of children (67% ≥0.4 mL/Kg, 44% ≥1.5 mL/Kg).
- CT-measured gastric volumes were moderately correlated with aspiration (Spearman's rho = 0.41, p = 0.0003), but CT volumes were higher than aspiration volumes.
Conclusions:
- Children administered clear fluids up to one hour before anesthesia can exhibit substantial gastric residual volumes.
- The findings suggest a need to re-evaluate current pediatric fasting guidelines and aspiration risk protocols.
- While vomiting occurred in three cases, no pulmonary aspiration was observed in the study cohort.
Abstract:
Background: Gastric fluid volume has been used as a surrogate marker for pulmonary aspiration risk in studies evaluating fasting protocol safety. This study measured residual gastric fluid volume in children using a protocol in which diluted oral contrast medium was administered up until one hour before anesthesia. Methods: This was a single-center prospective observational cohort trial of 70 children for elective abdominal/pelvic computed tomography (CT). Imaging was performed after diluted enteral contrast medium administration, beginning two hours before and ending at least one hour before induction. For each patient, gastric fluid volume was calculated using an image region of interest. The primary outcome measure was gastric fluid volume measured using the computed tomography image. Results: The median time from the end of contrast administration to imaging was 1.5 h (range: 1.1 to 2.2 h). Residual gastric volume, measured using CT was <0.4 mL/Kg in 33%; ≥0.4 mL/Kg in 67%; and ≥1.5 mL/Kg in 44% of patients. Residual gastric volumes measured using CT and aspiration were moderately correlated (Spearman's correlation coefficient = 0.41, p = 0.0003). However, the median residual gastric volume measured using CT (1.17, IQR: 0.22 to 2.38 mL/Kg) was higher than that of aspiration (0.51, IQR: 0 to 1.58 mL/Kg, p = 0.0008 on differences in paired measures). Three cases of vomiting were reported. No evidence of pulmonary aspiration was identified. Conclusions: Children who receive large quantities of clear fluid up to one hour before anesthesia can have a significant gastric residual volume.
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