We assessed the impact of raising the upper section of the bed, and patient positioning, on ultrasound assessment of gastric fluid contents. We performed ultrasound examinations in 25 subjects lying on their back, left and right sides at bed angles of 0°, 30°, 45°and 90°; this was carried out while the subjects were fasted, and repeated 10 min after drinking ≥ 50 ml water. After drinking, gastric contents were detected more frequently in the 45°semirecumbent position compared with the supine and 30°positions. The diagnostic performance of the Perlas qualitative grading scale to detect gastric fluid volume > 1.5 ml.kg À1 was improved at 45°, compared with 0°and 30°angles. The use of a composite ultrasound grading scale at a 45°angle was associated with the best performance, with a sensitivity and specificity of 82%. Antral cross-sectional area was significantly increased when measured in the right lateral position, but there was no effect of raising the bed. In conclusion, raising the upper section of the bed significantly affected qualitative assessment of gastric fluid contents. Further studies are required to determine the most appropriate composite ultrasound grading scale and bed angle for fast and reliable qualitative ultrasound detection of fluid volumes > 1.5 ml.kg À1 .

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Around a quarter of parturients with epidural analgesia and free access to clear fluids during labour presented higher estimated gastric content at full cervical dilatation. The SR-CSA may be of interest for the fast ultrasound assessment of the gastric content status in case of emergent obstetrical procedures at full cervical dilatation.

Background:The relationship between gastric fluid volume, volume of fluid regurgitated, and aspirated fluid volume remains unclear. Using a life-like manikin suitable for a pulmonary aspiration model, we aimed to assess the relationship between regurgitated and aspirated clear fluid volumes, and to determine the minimal value of the volume of liquid regurgitated that may lead to pulmonary aspiration of fluid volume ≥ 0.8 mL kg -1 (around 60 mL) that is likely to cause lung injury.Methods: Several volumes of water ranging from 30 to 150 mL were injected in a randomized order, at a flow rate of 20 mL per second, into the esophagus of a manikin lying in the supine position on a non-tilted table, with the manikin head in the extension or in the sniffing position. Aspirated volumes were measured in the manikin bronchi, by an investigator blinded to the volume injected. Aspiration was defined as positive when the volume of collected water was ≥ 60 mL for at least one of the five injections of each volume of water.Results: The minimal volume of water injected into the esophagus for an aspirated volume ≥ 0.8 mL kg -1 was 85 mL in the sniffing position, and was 150 mL in the extension position. Conclusions: These results suggest that the critical cut-off value of gastric fluid volume to be considered for the risk of significant pulmonary aspiration would be ≥ 85 mL (≥ 1 mL kg -1 ), in the sniffing position. These results should however be confirmed in further studies using other models.