The goal of this pilot prospective cohort study is to examine the reproducibility of gastric volume and emptying as measured by gastric ultrasound and its correlation to a gold-standard test for gastric emptying in the perioperative period in pediatric patients. The main questions it aims to answer are:
* What is the reliability (inter-rater variability between expert and novice assessors, and intra-rater variability) of a) the gastric antral cross-sectional area (CSA) and b) gastric volume using the Perlas US qualitative grading assessment, measured by using an ultrasound device in pediatric patients undergoing general anesthesia for elective surgery? * What is the correlation between ultrasound assessment of gastric emptying by the antral-CSA and gastric emptying determined by the acetaminophen absorption test (AAT), the gold standard?
The study will include two cohorts. Cohort assignment will be based on age and anesthesia induction plan. Subjects \>7yrs of age and expected to get an IV induction will be assigned to Cohort #1. Subjects \<7yrs of age and not expected to get an IV induction will be assigned to Cohort #2.
* Cohort 1 will include abdominal ultrasound for gastric assessment AND the acetaminophen absorption test which includes administering enteral acetaminophen (tylenol) with 6 oz of water and drawing of blood samples through a peripheral intravenous line. * Cohort 2 will include subjects for whom a peripheral intravenous line placement is not part of routine pre-operative care. Procedures for Cohort 2 will include abdominal ultrasound only in the pre-op area (no tylenol). This cohort is included to examine the reliability of measurements across age groups.
Perioperative patients with ASA classification 1-2
Ages: 2 years- less than 18 years
Locations: Longwood and Waltham campuses of Boston Childrens Hospital
History of gastrointestinal surgery
Gastrostomy
Known GI dysmotility (cohort 1 only)
Acetaminophen allergy (cohort 1 only)
This study is enrolling healthy pediatric subjects ages 2 through 17 years of age who are undergoing surgery with anesthesia at Boston Children's Hospital.
Cohort
Prospective
Gastric Ultrasound Baseline Scans
Diagnostic testThe patient's abdomen will be scanned using the ultrasound device by an expert scanner and novice scanner for baseline assessment of the antral CSA and gastric volume using Perlas US qualitative grading assessment.
Acetaminophen Absorption Test (AAT)
Diagnostic testPrior to starting the AAT, a baseline plasma acetaminophen level (250 microliters) will be obtained from the intravenous catheter. The subject will then be given 12.5 mg/kg or max 650mg of single batch 32mg/mL acetaminophen followed by 6oz of water PO. Up to 3 additional small volume blood samples will be drawn for acetaminophen levels. These additional blood samples (250 microliters each) will be obtained to measure acetaminophen plasma levels at the following goal intervals after acetaminophen administration.T1:10-20 mins, T2:35-45 mins, T3: 60mins. At the time of each lab draw gastric ultrasound will be assessed by the expert scanner to correlate gastric ultrasound with the acetaminophen absorption test as a gold-standard of gastric emptying.
Gastric Ultrasound Serial Scans
Diagnostic testCohort 1 will have multiple scans as part of assessing gastric emptying. These sequential scans after the baseline assessment will be done in line with the Acetaminophen Absorption Test timeline (T1:10-20 mins, T2:35-45 mins, T3: 60mins) and will be performed by an expert scanner only.
Inter-rater reliability
Measured using the following quantitative and qualitative ultrasound assessments between a novice and an expert gastric ultrasound operator: * Qualitative using the previously published Perlas' US qualitative grading assessment * Grade 0- no contents visualized in supine and lateral position * Grade 1- contents visualized in the lateral decubitus position (RLD) only * Grade 2- contents visualized in the supine and RLD. * Quantitative assessment using the cross-sectional area as published by Spencer AO et al. * Measurement of the CSA: longitudinal diameter (D1), and the antero-posterior diameter (D2) in both supine and RLD. Then these will be used to calculate the cross-sectional area (CSA) = (π\*D1\*D2)/4. * Quantitative assessment using the cross-sectional area as published by Spencer AO et al. * Measurement of the CSA: longitudinal diameter (D1), and the antero-posterior diameter (D2) in both supine and RLD. Then these will be used to calculate the cross-sectional area (CSA)
Intra-rater reliability
Measured using the following quantitative and qualitative ultrasound assessments between a novice and an expert gastric ultrasound operator: * Qualitative using the previously published Perlas' US qualitative grading assessment * Grade 0- no contents visualized in supine and lateral position * Grade 1- contents visualized in the lateral decubitus position (RLD) only * Grade 2- contents visualized in the supine and RLD. * Quantitative assessment using the cross-sectional area as published by Spencer AO et al. * Measurement of the CSA: longitudinal diameter (D1), and the antero-posterior diameter (D2) in both supine and RLD. Then these will be used to calculate the cross-sectional area (CSA) = (π\*D1\*D2)/4.
Gastric Emptying
Outcome will be gastric emptying assessed by the change in antral CSA (measured in cm2) over time after acetaminophen administration, and this will be correlated to gastric emptying over the same period of time by the acetaminophen absorption test PK parameter, AUC60 mcg\*min/mL. As such, each patient will act as their own control. Correlation analysis will be applied to examine the performance of CSA measurements overtime using gastric ultrasound to determine gastric emptying compared to the acetaminophen absorption test as the gold standard.
Post-anesthetic outcomes
Fasting times have been correlated to post-anesthetic outcomes such as post-operative nausea/ vomiting, and discomfort, and it is known that some patients fast longer than required by their clinical team, which can result in adverse effects. Reported fasting times for all patients and confirmatory assessment by gastric US will be examined along with data pulled from the medical record about post-operative nausea/ vomiting, post-operative discomfort, satisfaction, and whether the patient met their expected post-operative trajectory or not (e.g. unplanned admission).
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