Effect of patient head position on the aspirated volume of regurgitated clear fluid. A fresh human cadaver study

Abstract

Pulmonary aspiration of gastric contents is mainly due to regurgitation or vomiting that may occur during laryngoscopy or tracheal extubation, or during ventilation via a laryngeal mask airway, or in sedated patients [1,2]. Increased gastric content volume is one of the conditions required for aspiration to occur; it is also a determining factor of the severity of pulmonary injury related to aspiration [3]. Thus, results of previous animal studies have suggested that aspiration of acidic fluid volume ≥ 0.8 mL kg -1 may result in severe lung injury in humans [3].The relationship between gastric fluid volume and pulmonary aspiration may be divided into two steps: a first step corresponding to the occurrence of regurgitation or of vomiting, and a second step corresponding to the relationship between regurgitated (or vomited) volume and aspirated volume of fluid. The first step is multifactorial as it depends on the decrease in the lower oesophageal sphincter pressure due to general anaesthesia and/or on the increase in intragastric pressure due to a full stomach or to

Diagnostic accuracy of a simple qualitative ultrasound assessment for the diagnosis of empty stomach in the adult: A supplementary analysis of a prospective observer‐blind randomized crossover study

“…In addition to this result, it would be relevant to determine the diagnostic accuracy of the ultrasound visualization of an empty antrum in the semirecumbent position for the diagnosis of an “empty stomach”. Gastric fluid volume <0.8 mL.kg −1 can be considered as a relevant threshold value to define an “empty stomach”, because gastric fluid volume ≥0.8 mL.kg −1 is infrequent in elective fasted patients; 9 furthermore, it has been established that volume of aspirate ≥0.8 mL.kg −1 may have detrimental pulmonary consequences, 10,11 and that 0.8 mL.kg −1 of water injected into the esophagus could lead to aspirated volume up to 0.8 mL.kg −1 in fresh human cadavers in the sniffing position 12 . Thus, gastric fluid volume ≥0.8 mL.kg −1 may favor the occurrence of aspiration when associated with other risk factors, 13,14 while volume <0.8 mL.kg −1 is associated with very low risk of aspiration and pulmonary injury.…”