Diagnostic Accuracy of Point-of-Care Gastric Ultrasound

BACKGROUND: Pulmonary aspiration of gastric contents is associated with significant perioperative morbidity and mortality. Previous studies have investigated the validity, reliability, and possible clinical impact of gastric ultrasound for the assessment of gastric content at the bedside. In the present study, we examined the accuracy (evaluated as sensitivity, specificity, and likelihood ratios) of point-of-care gastric ultrasound to detect a "full stomach" in a simulated scenario of clinical equipoise. METHODS: After a minimum fasting period of 8 hours, 40 healthy volunteers were randomized in a 1:1 ratio to either remain fasted or ingest a standardized quantity of clear fluid or solid. Each subject was randomized twice on 2 independent study sessions at least 24 hours apart. A gastric ultrasound examination was performed by a blinded sonographer following a standardized scanning protocol. Using a combination of qualitative and quantitative findings, the result was summarized in a dichotomous manner as positive (any solid or >1.5 mL/kg of clear fluid) or negative (no solid and ≤1.5 mL/kg of clear fluid) for full stomach. RESULTS: Data from 80 study sessions were analyzed. In this simulated clinical scenario with a pretest probability of 50%, point-of-care gastric ultrasound had a sensitivity of 1.0 (95% confidence interval [CI], 0.925–1.0), a specificity of 0.975 (95% CI, 0.95–1.0), a positive likelihood ratio of 40.0 (95% CI, 10.33–∞), a negative likelihood ratio of 0 (95% CI, 0–0.072), a positive predictive value of 0.976 (95% CI, 0.878–1.0), and a negative predictive value of 1.0 (95% CI, 0.92–1.0). CONCLUSIONS: Our results suggest that bedside gastric ultrasound is highly sensitive and specific to detect or rule out a full stomach in clinical scenarios in which the presence of gastric content is uncertain. Accepted for publication February 27, 2018. Funding: This study was supported by a peer-reviewed grant from Physician Services Incorporated, Ontario, Canada. Conflicts of Interest: See Disclosures at the end of the article. Trial Registry Number: Registration ID: NCT02588495. Reprints will not be available from the authors. Address correspondence to Anahi Perlas, MD, FRCPC, Department of Anesthesia and Pain Management, Toronto Western Hospital, University Health Network, Department of Anesthesia, University of Toronto, 399 Bathurst St, McLaughlin Pavilion 2–405, Toronto, ON M5T 2S8, Canada. Address e-mail to anahi.perlas@uhn.ca. © 2018 International Anesthesia Research Society

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