Diagnostic Performance of Gastric Ultrasound in Children

Sensitivity and specificity of the qualitative examination of the gastric antrum for the detection of gastric fluid volume ≥ 1.25 ml/kg in the 45° semirecumbent position

Pulmonary aspiration of gastric contents is a complication responsible for the third highest
 cause of anaesthesia-related mortality in France, and for 50% of airway management-related
 mortality in the UK. The occurrence of pulmonary aspiration of gastric contents is often the
 result of a poor assessment of the risk of a full stomach, and could therefore often be
 avoided if the preoperative gastric contents were known to the anaesthetist. It is therefore
 useful to be able to discriminate easily between patients at risk of aspiration and those at
 low risk before general anaesthesia, and this can be done by ultrasound examination of the
 gastric contents in the gastric antrum, non-invasively (abdominal ultrasound) using a 2-5 MHz
 abdominal ultrasound probe or a high-frequency linear probe in small children (under 10 kg).
 European recommendations on preoperative fasting in paediatrics recommend that the
 examination should be interpreted in a qualitative manner only, without measuring the antral
 surface. However, the diagnostic performance of this qualitative approach alone has never
 been evaluated. The aim of this study was to determine the diagnostic performance of the
 qualitative assessment of gastric contents by ultrasound in children, and to compare it with
 that of the clinical algorithm, for the detection of a volume of fluid greater than 1.25
 ml/kg.
 
 Children will present themselves in the morning after fasting. Upon arrival, if their weight
 is not known, the children will be weighed. Subsequently, they will be positioned on an
 examination table in a supine inclined position at 45° (head of the bed elevated). An initial
 gastric ultrasound will be performed by a physician (investigator 1) who will not conduct the
 study ultrasounds. This initial ultrasound aims to confirm the absence of gastric content in
 the supine and right lateral decubitus positions, thereby establishing gastric emptiness.
 
 Investigator 1 will then proceed with the random selection of the clear liquid volume to be
 ingested for the study.
 
 The child will then be asked to drink this determined volume of clear liquid (water or apple
 juice according to their preference), as per the randomization results, under the supervision
 of the first investigator who performed the initial ultrasound.
 
 Subsequently, investigator 2 will perform a gastric ultrasound blindly with respect to the
 ingested liquid volume, three minutes after the consumption of the clear liquid. The
 examination will last a maximum of 3 minutes.
 
 Non-invasive gastric antrum ultrasound examinations will utilize a probe with a frequency of
 2-5.5 MHz and a linear probe with a frequency of 10 MHz, enabling the evaluation of the
 gastric antrum's appearance. The diameters (longitudinal D1 and anteroposterior D2) of the
 antrum will also be measured in the supine (semi-seated and lying) and right lateral
 positions in the sagittal plane passing through the abdominal aorta and the left lobe of the
 liver, for the calculation of the antral section area, given by the formula: Antral area = π
 x D1 x D2 / 4.