Observations on intragastric pressure

Abstract

Regurgitation of stomach contents, as distinct from vomiting, is the result of a sufficiently high intragastric pressure overcoming the competence of the cardia.In the last fifteen years there have been several studies designed to demonstrate the nature of the cardiac sphincter and to evaluate the pressure required to cause retrograde flow through it13zp 3,4. By contrast, there has been much less consideration given to values for intragastric pressure.Our interest in this matter stemmed from anxiety for the pregnant woman with a breech presentation, already in the lithotomy position, requiring general anaesthesia for delivery of the after-coming head. It seemed that the combination of an intra-abdominal mass together with positioning which would raise the mass higher in the abdominal cavity might be expected to raise intragastric pressure above the non-pregnant value. We have set out to determine the magnitude and significance of the increase. METHODSFour groups of patients have been investigated: 23 men, 36 children, 43 non-pregnant women, all for elective surgery under general anasthesia; and 31 pregnant women, at term, for delivery under general anasthesia. No selection was made with regard to height, weight and age although these were recorded. The children ranged in age from 7 months to 12 years.The patients were pre-medicated with an opiate, where appropriate, and all were given atropine or scopolamine. All adults were pre-oxygenated and anaesthesia induced with a sleep dose of thiopentone which was immediately followed by lOOmg suxamethonium. Without attempting to ventilate the lungs, a cuffed endotracheal tube 249

Heartburn and Regurgitation in Pregnancy: The Effect of Fat Ingestion

“…It has been proposed that increased abdominal pressure by the enlarged uterus may contribute to the occurrence of reflux during pregnancy. However, the findings in the literature are conflicting [30,31]. Given that regurgitation is frequent in pregnancy (74% in our sample), further studies are needed to investigate this condition.…”

Practice makes perfect? Evaluation of cricoid pressure task training for use within the algorithm for rapid sequence induction in critical care

“…The application of cricoid force results in a fall in lower oesophageal sphincter tone, whereas suxamethonium-induced fasciculations produce a rise in mean intragastric pressure. 20,[25][26][27] Previous research has demonstrated that accurately applied cricoid force in excess of 30 N occluded the upper oesophagus, creating an effective barrier to regurgitation and aspiration. [14][15][16] Although Wraight et al extrapolated from their research that a force of 44 N would prove protective in situations of elevated intragastric pressure, most commentators recommend 30-40 N as the target range.…”

Airway obstruction with cricoid pressure

“…Can we apply less force and still prevent regurgitation? In practice it would seem that gastric pressures are generally < 25 mmHg in the supine position under general anaesthesia [14,15], even during emergency Caesarean section with a full stomach [16]. Therefore 30 N of force is probably more than enough to prevent regurgitation [11].…”