Assessment of Gastric Volumes in Preoperative Paediatric Surgical Patients with intake of water or tender coconut water – An ultrasound based randomised controlled study

Thorough preoperative evaluation and necessary investigations are carried out and informed consent of patients / parents / assent of 4-12 years of age of either gender scheduled for elective surgeries are taken.

Children are randomly allotted to one of the 2 groups, to receive either plain water (Group A) or tender coconut water (Group B) by computer generated randomization via Research Randomizer software (www.randomizer.org). The allocation concealment is ensured using sequentially numbered opaque sealed envelope (SNOSE) technique. Only the investigator monitoring the patient postoperatively is blinded for the group allotment.

Nil per oral for both solids and liquids will be advised from 11PM- 7 AM on the day of scheduled surgery. During the preoperative evaluation, the patient will undergo gastric ultra sound examination in the ‘preinduction room’, to develop acquaintance with the patient and to reduce the anxiety of newer environment to the child on the day of surgery (the Preinduction room being about 50 feet from the sterile zone of the operating theater). No specific sedation is advised for the patients.

At 7 AM all the patients will undergo gastric ultrasound evaluation with SONOSITE-SII using high frequency paediatric linear probe (13 MHz- 6 MHz) (L25) or low frequency curve-linear probe (5 MHz- 2 MHz) (C60) (whichever provides best images). The basal gastric parameters will be noted in 2 groups (Group A and Group B). Intravenous fluid is not administered for the next 2 hours. The group A children receives plain water and group B children receive tender coconut water, both at 3ml/kg body weight. Ultrasonography assessment is next performed at 7.30 AM, 8.00AM, 8.30 AM and 9.00AM and gastric volumes and contents are noted.

Patient will be first scanned in a supine position, followed by right lateral position (RLP). In both positions, the gastric antrum will be identified. The ultrasonographic examination will be done by the post graduate under the supervision of the guide. The post graduate would have performed at least 50 examinations (10 patients) under guidance of the experienced guide in the pilot testing before actual recruitment of patients. A qualitative assessment will also be performed to identify material in the stomach (solid or liquid) and gastric antral grading, as described by Perlas et al as follows:

Grade 0= Absence of fluid in both supine and RLP;

Grade 1=fluid in RLP only;

Grade 2=fluid in both supine/semi recumbent and RLP;

Quantitative assessment will be performed by measuring antral cross-section area (CSA) and antral volume. The antral CSA will be calculated by measuring two perpendicular diameters. In longitudinal (D1) and anteroposterior (D2) plane from serosa to serosa and using the formula:

CSA=π[D1×D2]/4.

Four measurements of gastric antral CSA will be obtained for each patient, supine position and three in RLD (averaged to obtain a mean value). The following mathematical model will be used to calculate the volume of gastric contents and to determine the volume in ml/kg.

Volume=27.0+ (14.6×CSA) - (1.28×Age)

The random blood glucose (RBS) will be checked with glucometer (ONE TOUCH SELECT) immediately on induction and time noted.

Data Management and Statistics:

The data will be entered in MS Excel Sheet, cleaned, and the averages / means, proportions / percentages, gradings (descriptive statistics) are noted. The continuous variables related to the gastric volumes at different intervals (values in ml and as ml per Kg) are expressed in Mean Standard deviation (SD), and so will be the CSA (cm2). The Perla’s gastric antral grading – the ordered categorical variable will be expressed as proportion / percentages and so will be the grouping of patients based on different levels of gastric volume per kg and others related to the patient characteristics such as age, as necessary. The data will be checked for uniformity of distribution and if not, subjected to ‘goodness of fit’ tests for normalcy. For numerical data, for parametric data, Paired T test will be used within group and Student’s T test for 2 group comparison. For non-parametric data even after logarithmic correction, Wilcoxon signed rank test and Wilcoxon rank sum tests will be used for within group and unrelated samples respectively. For categorical variables, McNemar or Chi square test will be used for related or unrelated samples. The p values at <0.05 will be taken as significant for the purpose of the inferential statistical tests.