An interventional study of 24-hour clear liquid diet and Standard fasting guidelines in Residual Gastric Contents and Pulmonary Aspiration of Gastric Contents, sponsored by St Vincent's Hospital Melbourne. Recruiting at 2 sites in Australia. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-05-11.
Sponsored by St Vincent's Hospital Melbourne · Not applicable, Interventional, and Prevention
The aim of this randomised controlled trial is to determine the effect of a 24-hour clear liquid diet compared to standard fasting guidelines on the proportion of participants who present with increased residual gastric contents during their study visit. It also aims to determine the effect of a 24-hour clear liquid diet compared to standard fasting guidelines on:
We will enrol adults who are currently using any once-weekly glucagon-like peptide-1 receptor agonist (GLP-1RA) medication. Participants will be allocated in a 1:1 ratio to follow a 24-hour clear liquid diet or standard fasting guidelines prior to attending a study visit where participants will undergo a blinded gastric ultrasound assessment.
GLP-1 RAs have had a transformative impact on the management of obesity, cardiovascular disease, and type 2 diabetes. Despite this, this class of medications pose a significant challenge in the perioperative setting, as GLP-1 RAs are known to increase patients' risk of presenting to surgery with residual gastric contents even when standard fasting guidance is adhered to. Such residual contents pose a risk for devastating complications if they are aspirated during surgery. In procedures such as upper endoscopy, where clear visualisation of the gastric tract is essential, the presence of residual contents in the stomach may result in procedures being aborted, leading to patients being exposed to additional risks associated with having to repeat the procedure. Despite the urgent need for clear guidance based on reliable evidence, healthcare professionals are currently practicing in an almost complete absence of evidence regarding the management of GLP-1 RAs in the perioperative period.
Our trial aims to address the uncertainty around pre-procedure management of patients using GLP-1 RAs by evaluating whether a 24-hour clear liquid diet can reduce the likelihood of increased residual gastric contents in patients using once-weekly GLP-1 RA medications, compared to the standard fasting guidelines currently recommended before elective procedures. Standard fasting guidelines, as defined by the ASA and ANZCA, recommend clear liquids up to 2 hours before anaesthesia, a light or low calorific meal up to 6 hours before anaesthesia, and fasting from fried foods, fatty foods, or meat for at least 8 hours prior to anaesthesia.The trial will also examine the effect of this more stringent fasting guidance on outcomes including thirst, hunger, nausea, fatigue, and anxiety, which impact both comfort and satisfaction among patients undergoing surgery.
27 studies on the registry are indexed under Respiratory Aspiration of Gastric Contents; 6 are open to participants now.
This study's planned enrollment of 154 is above the median of 101 across 16 interventional studies indexed under Respiratory Aspiration of Gastric Contents.
Browse Respiratory Aspiration of Gastric Contents studies →St Vincent's Hospital Melbourne is the lead sponsor of 17 studies on the registry; 4 are open to participants now.
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Exclusion Criteria:
Participants meeting any of the following criteria, indicative of abnormal anatomy and not validated by gastric ultrasound, will be excluded from this trial:
In addition, participants meeting any the of following criteria will be excluded from this trial:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Other: 24-hour clear liquid diet
Other: Standard fasting guidelines
Participants randomly assigned to this arm will be instructed to follow a 24-hour clear liquid diet, defined as NPO for solids and last intake of clear liquids no less than 2 hours prior to the trial visit.
Participants randomly assigned to this arm will be instructed to follow the ASA and ANZCA standards for preoperative fasting prior to presenting for their trial visit. This requires participants to only consume clear liquids up to 2 hours, a light or low calorific meal up to 6 hours, and fasting from fried foods, fatty foods, or meat for at least 8 hours prior to the trial visit.
Residual gastric contents
Difference in proportion of participants who present with increased residual gastric contents, defined as \>1.5mL/kg of clear fluids, thick fluids or solids, as assessed by gastric ultrasound using the clinical algorithm by Perlas and colleagues.
Time frame: Immediately following fasting intervention
Solid content or thick fluids
Difference in proportion of participants who present with solid content or thick fluids, assessed by gastric ultrasound using the clinical algorithm by Perlas and colleagues.
Time frame: Immediately following fasting intervention
Thirst
Mean difference in thirst, assessed using the thirst distress and thirst intensity Visual Analogue Scales. Participants rate their level of thirst distress along a scale of 0-10cm, where 10cm represents "extreme distress" and the end closest to 0cm the represents "not distressed". Participants rate their level of thirst intensity along a scale of 0-10cm, where 10cm represents "intense thirst" and the end closest to 0cm the represents "not thirsty". The average of the thirst intensity and the thirst distress score is calculated.
Time frame: Immediately following fasting intervention
Hunger
Mean difference in hunger, assessed using the Hunger and Satiety Visual Analogue Scale. Participants rate their level of hunger along a scale of 0-10cm, where 10cm represents "I have never been more hungry, and the end closest to 0cm the represents "I am not hungry at all".
Time frame: Immediately following fasting intervention
Nausea
Mean difference in nausea, assessed using a Visual Analogue Scale. Participants rate their level of nausea along a scale of 0-10cm, where 10cm represents "worst imaginable nausea", and the end closest to 0cm the represents "no nausea".
Time frame: Immediately following fasting intervention
Fatigue
Mean difference in fatigue, assessed using a Visual Analogue Scale. Participants rate their level of fatigue along a scale of 0-10cm, where 10cm represents "extreme fatigue", and the end closest to 0cm the represents "not fatigued at all".
Time frame: Immediately following fasting intervention
Anxiety
Mean difference in anxiety, assessed using the Visual Analogue Scale for Anxiety (VAS-A). Participants rate their level of anxiety along a scale of 0-10cm, where 10cm represents "most anxious I can imagine, and the end closest to 0cm the represents "not at all anxious".
Time frame: Immediately following fasting intervention
Adherence to intervention
Difference in proportion of participants who adhere to allocated intervention, assessed using a dedicated case report form.
Time frame: Immediately following fasting intervention
Time since last oral intake of solid foods
Mean difference in time since last oral intake of solid foods, assessed using a dedicated case report form.
Time frame: Immediately following fasting intervention
Time since last oral intake of clear liquids
Mean difference in time since last oral intake of clear liquids, assessed using a dedicated case report form.
Time frame: Immediately following fasting intervention
Plan to share: Yes — The following will be made available long-term for use, by request, from future researchers from a recognised research institution whose proposed use of the data has been ethically reviewed, approved by an independent committee, and can demonstrate a safe data management plan.
Supporting information: Study protocol, Statistical analysis plan, Analytic code
Time frame: Upon request
Access criteria: By request, from future researchers from a recognised research institution whose proposed use of the data has been ethically reviewed, approved by an independent committee, and can demonstrate a safe data management plan.
Started Jun 2025 (actual). Primary completion is estimated for Feb 2027, 19 months after the start.
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St Vincent's Hospital Melbourne