title: Gastric ultrasound as a preoperative bedside test for residual gastric contents volume in children.
abstract: BACKGROUND
  Emergency situations and conditions with impaired gastric emptying enhance the risk of perioperative pulmonary aspiration due to increased residual gastric contents volume (GCV). Gastric ultrasonographic (US) measurement of the gastric antral cross-sectional area (CSA) has been proposed to estimate preanesthetic GCV. However, only few healthy children and fasted pediatric patients have been investigated so far, predicting GCV with considerable imprecision. This study aimed to compare GCV assessed by US in different patient positions for measuring CSA, using magnetic resonance imaging (MRI) as reference, and to evaluate its potential as diagnostic test.
  
  
  METHODS
  Healthy volunteer children were examined in a crossover design on 2 days. After baseline examination, they received a light breakfast, followed by 7 ml·kg-1clear fluid after 2 or 4 h. Gastric emptying was examined with MRI over 4 or 6 h, respectively. US was performed immediately after MRI in right lateral decubital (RLD) and supine with upper body elevated (SUBE) positions. Correlation coefficients (Pearson R; 95%CI) between CSA and body weight corrected GCV (GCVw) as determined by MRI volumetry were calculated. Data are presented as median (range).
  
  
  RESULTS
  Eighteen children aged 9.8 (6.8-12.2) years had 72 US examinations completed. CSA was 401 (101-1311) mm2and 271 (118-582) mm2, and R between CSA and GCVwwas 0.76 (0.76-1) and 0.57 (0.41-0.88) for the RLD and SUBE positions, respectively. The corresponding GCVwwas 2.1 (0.1-13.8) ml·kg-1. A linear regression model from RLD was similar to one previously derived. Bland-Altman analysis and ROC plots are presented.
  
  
  CONCLUSIONS
  CSA correlated with GCVwin healthy children over a wide range of gastric filling, with the RLD position clearly superior to the SUBE position, confirming a previously derived formula. Although direct calculation of GCVwis imprecise, this technique has the potential to become a diagnostic risk assessment test.
authors.affiliation: Department of Anesthesiology, University Children's Hospital, Zurich, Switzerland.|Children's Research Center, University Children's Hospital, Zurich, Switzerland.
authors.forename: Achim
authors.initials: A
authors.lastname: Schmitz
authors.affiliation: Department of Anesthesiology, University Children's Hospital, Zurich, Switzerland.|Children's Research Center, University Children's Hospital, Zurich, Switzerland.
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Schmidt
authors.affiliation: Department of Anesthesiology, University Children's Hospital, Zurich, Switzerland.|Children's Research Center, University Children's Hospital, Zurich, Switzerland.
authors.forename: Philipp K
authors.initials: PK
authors.lastname: Buehler
authors.affiliation: Children's Research Center, University Children's Hospital, Zurich, Switzerland.|Department of Diagnostic Imaging, University Children's Hospital, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schraner
authors.affiliation: Department of Anesthesiology, University Children's Hospital, Zurich, Switzerland.|Children's Research Center, University Children's Hospital, Zurich, Switzerland.
authors.forename: Melanie
authors.initials: M
authors.lastname: Frühauf
authors.affiliation: Department of Anesthesiology, University Children's Hospital, Zurich, Switzerland.|Children's Research Center, University Children's Hospital, Zurich, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Weiss
authors.affiliation: Division of Psychiatry and Psychotherapy, University Hospital, Zurich, Switzerland.
authors.forename: Richard
authors.initials: R
authors.lastname: Klaghofer
authors.affiliation: Children's Research Center, University Children's Hospital, Zurich, Switzerland.|Department of Diagnostic Imaging, University Children's Hospital, Zurich, Switzerland.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Kellenberger
mesh_terms: D002648:Child; D018592:Cross-Over Studies; D005260:Female; D005766:Gastrointestinal Contents / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D000067716:Point-of-Care Testing; D011300:Preoperative Care / Q000379:methods*; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods*
keywords: gastric antral area; gastric volume; preoperative fasting; ultrasound