Aspiration pneumonia is a dreaded complication of anaesthesia because of its prevalence (1/3,886 cases in elective anaesthesia and 1/895 cases in emergency settings) and its high morbidity and mortality (3 to 9%). This chemical and/or infectious pneumonia is secondary to passage of the gastric contents into the unprotected upper airways during general anaesthesia. The prognosis depends on three factors: the presence of food debris, and the acidity and volume of the gastric contents. To prevent this complication, the French society of anaesthesia and intensive care recommends preoperative fasting rules and, in patients presenting risk factors for aspiration, the use of antacids and rapid sequence intubation. This preventive strategy is associated with certain adverse events: deferred operative procedures, discomfort and hypoglycaemia secondary to fasting, more frequent anaphylactic complications, and memory of anaesthetic induction.

Over recent years, ultrasound has become more widely used by anaesthetists for local anaesthesia, vascular catheterization, haemodynamic monitoring and, more recently, 2D ultrasound estimation of intragastric volume. However, 2D ultrasound estimation of intragastric volume presents several limitations: because of the complex shape of the stomach, this technique requires a long learning curve and the measured volume is poorly correlated with reference techniques (MRI and 99Tc scintigraphy). Two studies have recently measured intragastric volume by three dimensional ultrasound with promising results.

Inclusion Criteria:

• Healthy volunteers over the age of 18 years employed by Amiens University Hospital and covered by French national health insurance.
• Fasting (last meal > 6 hours and last drink of water, tea or coffee > 2 hours)
• Signature of the free and informed written consent form.

Exclusion Criteria:

• Pregnant woman.
• Presence of diseases or treatments that alter (slow or accelerate) gastric emptying.
• Presence of swallowing disorders.
• History of gastric or supramesocolic surgery.

Healthy volunteers fasting