* The goal of this observational study is to learn whether the stomach takes longer to empty in patients on the intensive care unit who are receiving ECMO (a machine that temporarily takes over the role of the lungs and heart) compared to patients receiving support through a breathing machine (mechanical ventilation) only. It will also find the best way to measure stomach emptying at the bedside. * The main questions it aims to answer are:
* What is the prevalence of slow stomach emptying and other stomach or bowel problems in patients receiving ECMO, compared to patients receiving mechanical ventilation but not receiving ECMO? (Stage A) * What is the best bedside method to measure stomach emptying in patients receiving ECMO? (Stage B) * Stage A of the study will involve measuring stomach emptying in study participants within four days of ICU admission, using two bedside methods:
* 'Residual volumes' (removing liquid nutrition left in the stomach with a syringe, after this has been given through the participant's usual feeding tube) * A stomach ultrasound scan The researchers will check for differences between patients receiving ECMO versus no ECMO, and how this relates to the nutrition patients receive and how well or unwell they become in ICU. * In a smaller subgroup of patients receiving ECMO and participating in Stage B of the study, the researchers will also use scintigraphy. This is a standard research scan that tracks how the stomach empties by mixing a small, safe amount of radioactivity in the participant's usual liquid nutrition. The researchers will compare stomach emptying results from 'residual volumes' and stomach ultrasound with scintigraphy.
Within 72 hours of Guy's & St Thomas' ICU admission
Mechanically ventilated adults (≥18 years)
Receiving enteral nutrition (liquid nutrition) via a gastric (nasogastric or orogastric) feeding tube
Informed consent / advice for participation by consultee
Pregnancy
History of gastroparesis (long-term slow stomach emptying)
Current acute or long-term gastrointestinal pathology (stomach or bowel problem) that may influence gastric emptying (e.g. inflammatory bowel disease, coeliac disease, pancreatic exocrine insufficiency)
Current contraindication to enteral nutrition (liquid nutrition) (e.g. clinical or radiological evidence of bowel obstruction, bowel ischaemia, ileus, upper gastrointestinal bleeding)
Patients receiving mechanical ventilation (including those receiving ECMO) admitted to the Guy's \& St Thomas' Adult ICUs during the study period will be screened consecutively for eligibility against the inclusion / exclusion criteria. Eligibility screening will be done using the electronic healthcare record within 72 hours of admission to the participating ICU. All patients meeting all of the inclusion criteria and none of the exclusion criteria will be approached for consent and considered for recruitment if logistically feasible (i.e. if a trained staff member is available on site to undertake the gastric ultrasound/scintigraphy measurements). The total target sample size for this study is 72 patients (36 receiving ECMO; 36 not receiving ECMO).
Cohort
Prospective
Gastric (stomach) ultrasound measurement
Other interventionGastric ultrasound will be performed within 4 days of admission to the participating ICU, for all 72 participants included in Stage A of the study. An ultrasound machine will be gently pressed against the participant's abdomen to measure how much liquid nutrition is left in their stomach over time. To do this, 100ml of liquid nutrition will be given through their gastric tube at the start of the scan. Five measurements will be taken in total, one at the start (baseline) and then one every hour for a total of four hours. A special measurement from the ultrasound scan ('antral cross-sectional area') will be used to calculate the amount of liquid in the stomach. In preparation for the scan, the participant's regular liquid nutrition will be paused for at least 4 hours.
'Residual volume' measurement
Other intervention'Residual volumes' are measured every four hours by nurses in ICU as part of routine care. A 'residual volume' measurement will be done for all 72 participants included in Stage A of the study immediately before the ultrasound scan. The measurements taken from each participant during the first 7 days of their ICU stay (including the 24 hours before gastric ultrasound measurements) will also be recorded from the electronic healthcare records.
Scintigraphy (standard research method)
Other interventionIn addition to gastric ultrasound and residual volumes, scintigraphy will also be carried out for a subgroup of 27 patients receiving ECMO (i.e. those participating in stage B) to measure stomach emptying and stomach retention. The liquid nutrition given at the start of the scan will be mixed with a small and safe amount of radioactivity by a specialist Nuclear Medicine Physicist. A special camera (portable gamma camera) will then be placed over the participant's stomach, which will take images over four hours (one at baseline, then one every 15 minutes for the first hour, followed by every 30 minutes for the next three hours). Each scan will last up to 5 minutes. A Nuclear Medicine Physicist will then analyse the images. Patients who are suitable to have scintigraphy will be identified through discussion with their treating ICU consultant.
Prevalence of delayed gastric emptying (number of participants experiencing delayed gastric emptying) using stomach ultrasound in participants receiving ECMO compared to those receiving mechanical ventilation but not receiving ECMO (STAGE A).
The prevalence of delayed gastric emptying will be determined using stomach ultrasound ('antral cross-sectional area') in all 72 participants of Stage A (including ECMO and non-ECMO groups). The assessment of delayed gastric emptying prevalence will involve five stomach ultrasound measurements undertaken at pre-defined timepoints over a 4-hour duration. This will include calculation of percentage gastric retention (% of liquid nutrition volume remaining in stomach relative to that originally administered), which will be based upon measurements of 'antral cross-sectional area' (cm2) and subsequent calculation of stomach volume (millilitres, mL) (see interventions section). The definition of delayed gastric emptying prevalence using ultrasound will be determined based upon the optimum association with gastric emptying measured via scintigraphy, as identified in Stage B.
Prevalence of delayed gastric emptying (number of participants experiencing delayed gastric emptying) using 'residual volumes' in participants receiving ECMO compared to those receiving mechanical ventilation but not receiving ECMO (STAGE A).
The prevalence of delayed gastric emptying will be determined for all 72 participants of Stage A (including ECMO and non-ECMO groups) using 'residual volumes' measured in millilitres (mL) (see interventions section). Delayed gastric emptying will be defined as any 'residual volume' measurement of more than 400 mL (current local institutional protocol threshold).
Association of stomach ultrasound ('antral cross-sectional area') and 'residual volumes' for measuring stomach emptying compared with the standard research method of scintigraphy in participants receiving ECMO (STAGE B).
Stomach emptying will be measured using scintigraphy in a subgroup of 27 participants receiving ECMO from Stage A. This will be determined based upon a combination of percentage (%) stomach retention calculated at pre-defined timepoints over a 4-hour duration (see interventions section), as well as stomach emptying rate (i.e. time \[minutes\] taken for half of the infused liquid nutrition to empty). These parameters will be compared with the those from stomach ultrasound and 'residual volume' measurements to determine the bedside clinical method with the optimum association.
Prevalence of other gastrointestinal complications (number of participants experiencing other gastrointestinal complications)
Presence/absence of any of the following (as documented on electronic electronic healthcare records): * Vomiting * Bowel ischaemia (poor blood flow to the gut), identified via clinically indicated abdominal imaging * Upper-gastrointestinal bleeding (bleeding from the stomach or upper part of small bowel), identified via clinically indicated endoscopy * Diarrhoea, defined as: 1. For patients without a bowel management system: two consecutive days of ≥3 loose stools (type 6 or 7 on the Bristol Stool Form Scale) in the absence of laxatives; 2. For patients with a bowel management system: output of \>250ml in the absence of laxatives. * Constipation (defined to align with Rome IV Criteria for functional constipation), to include two of the following: 1. infrequent stools (bowels not opening for ≥3 consecutive days); 2. hard stools (classified as type 1 or 2 on the Bristol Stool Form Scale); 3. the requirement for laxative up-titration within one day of one of the first two symptoms
Nutritional status
Nutritional status (how well-nourished the participant is) will be measured by a Critical Care Dietitian using standardised assessment methods (i.e. Subjective Global Assessment). The association between delayed gastric emptying and other gastrointestinal complications with nutritional status will be explored.
Nutritional delivery (mean percentage of energy and protein targets achieved)
Nutritional delivery (the percentage of liquid nutrition the participant has received relative to their estimated energy and protein targets) will be measured daily by Critical Care Dietitians as part of routine care. The mean percentage nutritional delivery over the first 0-3, 4-7, and 8-14 days of ICU admission will be calculated. The association between delayed gastric emptying and other gastrointestinal complications with nutritional delivery will be explored.
Nutritional adequacy
Achievement of nutritional adequacy will be determined at the following timepoints, with adequacy defined according to current international critical care nutrition guidelines: * Days 0-3 of ICU admission (adequacy defined as 0-70% of mean energy and protein targets) * Days 4-7 of ICU admission (adequacy defined as 70-100% of mean energy and protein targets) * Days 8-14 days of ICU admission (adequacy defined as 80-110% of energy and protein targets) The association between delayed gastric emptying and other gastrointestinal complications with nutritional adequacy will be explored.
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Guy's and St Thomas' NHS Foundation Trust
Lead sponsor
King's College London
Collaborator
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