Ultrasonographic evaluation of gastric emptying time in obese and non-obese full term pregnant women planned for elective caesarean section following standardized meal.

Pulmonary aspiration of gastric contents is a rare but serious complication in obstetric anaesthesia and is associated with significant morbidity and mortality. Obesity results in a further increase in this risk because obesity is associated with hiatal hernia and increased intra-abdominal pressure which may further decrease the gastric emptying. This has led to a stringent adoption of preoperative fasting guidelines, that is six hours following solids and two hours following clear liquids. However there are no separate guidelines for fasting in obese patients. Gastric ultrasound is a non-invasive procedure which can be easily performed at bedside and help in rapid risk assessment of the patient.

Women admitted in the maternity ward of lok nayak hospital who fulfill the inclusion and exclusion criteria will be recruited for the study. A special note will be made of the height, weight and BMI of the patients in addition to a detailed pre-anaesthetic checkup. After ensuring an adequate fasting, that is six hours for solids and two hours for clear liquids, an ultrasound examination of abdomen will be performed using the available ultrasound machine equipped with a curvilinear probe (2 to 5 MHz) after making the patient lie in semi recumbent position with head elevated to 45degree. After obtaining a baseline value the participants will be made to ingest a standardized meal(100g flavoured yogurt: 136kcal, 4,1g protein, 4.6g fat, 19.5g carbohydrates) within 5 minutes and serial ultrasounds of gastric antral cross section will be measured at different time intervals-15min/90min/120min in a standardized saggital plane passing through abdominal aorta and left lobe of liver. Similar procedure will be followed for non-pregnant volunteer group as well.

The antral cross section area will be used to measure the gastric emptying fraction at 15-90 minutes and half time to gastric emptying. The number of women with empty stomachs at 90min and 120min after ingestion of meal will also be assessed.

For statistical analysis, comparison of normally distributed continous variables between the groups will be performed using ANOVA. Nominal categorical data between the groups will be compared using Chi-squared test or Fisher’s exact test and non-normal distribution categorical variables will be compared using Kruskal Wallis test and further paired comparisons will be done using Mann Whitney U test.