After approval by the Research Ethics Board of Mount Sinai
Hospital (Toronto, Canada), we conducted this observational
cohort study of a group of anaesthesiologists performing qualitative
US assessment of the gastric content in term pregnant
women. Written informed consent was obtained from all
the participants (anaesthesiologists and third trimester pregnant
women). The study was registered at ClinicalTrials.gov
(NCT01564030). We followed the Guidelines for Reporting Reliability
and Agreement Studies (GRRAS statement) in conducting
and reporting our investigation.26
The participating raters consisted of three anaesthesiologists
previously trained in qualitative US assessment of
gastric content in human male volunteers25 followed by
1-year of experience practicing the technique regularly. The inclusion
criteria for the rated subjects were non-labouring pregnant
women ≥32 weeks gestational age; ≥18 years; ASA
physical status I– III; weight 50–120 kg; height ≥150 cm;
ability to understand the rationale of the study assessments
and written informed consent. Exclusion criteriawere diabetes,
a history of upper gastrointestinal disease (including hiatus
hernia), and previous surgical procedures on the oesophagus,
stomach, or upper abdomen.
Subjects were recruited on the day preceding the study
assessments. Following an overnight fast of at least 8 h,
subjects were randomized into one of the three groups: (a)
Empty Group: to remain fasted until completion of the assessments;
(b) Clear Fluids Group: to drink 250 ml of apple juice
5 min before the assessments; (c) Solid Contents Group: to
eat a meal comprising a small muffin and coffee with cream
or milk between 5 and 15 min before the assessments.
Randomization was performed in blocks of six subjects
(two subjects per group) using a computer-generated list of
random numbers. Group allocation was concealed from the
raters using sealed opaque envelopes, which were prepared
and kept by an independent research assistant.