Aims The aim of this study was to evaluate the epidemiology and treatment of Perthes’ disease of the hip. Methods This was an anonymized comprehensive cohort study of Perthes’ disease, with a nested consented cohort. A total of 143 of 144 hospitals treating children’s hip disease in the UK participated over an 18-month period. Cases were cross-checked using a secondary independent reporting network of trainee surgeons to minimize those missing. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants. Results Overall, 371 children (396 hips) were newly affected by Perthes’ disease arising from 63 hospitals, with a median of two patients (interquartile range 1.0 to 5.5) per hospital. The annual incidence was 2.48 patients (95% confidence interval (CI) 2.20 to 2.76) per 100,000 zero- to 14-year-olds. Of these, 117 hips (36.4%) were treated surgically. There was considerable variation in the treatment strategy, and an optimized decision tree identified joint stiffness and age above eight years as the key determinants for containment surgery. A total of 348 hips (88.5%) had outcomes to two years, of which 227 were in the late reossification stage for which a hip shape outcome (Stulberg grade) was assigned. The independent predictors of a poorer radiological outcome were female sex (odds ratio (OR) 2.27 (95% CI 1.19 to 4.35)), age above six years (OR 2.62 (95% CI (1.30 to 5.28)), and over 50% radiological collapse at inclusion (OR 2.19 (95% CI 0.99 to 4.83)). Surgery had no effect on radiological outcomes (OR 1.03 (95% CI 0.55 to 1.96)). PROMs indicated the marked effect of the disease on the child, which persisted at two years. Conclusion Despite the frequency of containment surgery, we found no evidence of improved outcomes. There appears to be a sufficient case volume and community equipoise among surgeons to embark on a randomized clinical trial to definitively investigate the effectiveness of containment surgery. Cite this article: Bone Joint J 2022;104-B(4):510–518.

The aim of this study was to inform the epidemiology and treatment of slipped capital femoral epiphysis (SCFE).This was an anonymized comprehensive cohort study, with a nested consented cohort, following the the Idea, Development, Exploration, Assessment, Long-term study (IDEAL) framework. A total of 143 of 144 hospitals treating SCFE in Great Britain participated over an 18-month period. Patients were cross-checked against national administrative data and potential missing patients were identified. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants.A total of 486 children (513 hips) were newly affected, with a median of two patients (interquartile range 0 to 4) per hospital. The annual incidence was 3.34 (95% confidence interval (CI) 3.01 to 3.67) per 100,000 six- to 18-year-olds. Time to diagnosis in stable disease was increased in severe deformity. There was considerable variation in surgical strategy among those unable to walk at diagnosis (66 urgent surgery vs 43 surgery after interval delay), those with severe radiological deformity (34 fixation with deformity correction vs 36 without correction) and those with unaffected opposite hips (120 prophylactic fixation vs 286 no fixation). Independent risk factors for avascular necrosis (AVN) were the inability of the child to walk at presentation to hospital (adjusted odds ratio (aOR) 4.4 (95% CI 1.7 to 11.4)) and surgical technique of open reduction and internal fixation (aOR 7.5 (95% CI 2.4 to 23.2)). Overall, 33 unaffected untreated opposite hips (11.5%) were treated for SCFE by two-year follow-up. Age was the only independent risk factor for contralateral SCFE, with age under 12.5 years the optimal cut-off to define 'at risk'. Of hips treated with prophylactic fixation, none had SCFE, though complications included femoral fracture, AVN, and revision surgery. PROMs demonstrated the marked impact on quality of life on the child because of SCFE.The experience of individual hospitals is limited and mechanisms to consolidate learning may enhance care. Diagnostic delays were common and radiological severity worsened with increasing time to diagnosis. There was unexplained variation in treatment, some of which exposes children to significant risks that should be evaluated through randomized controlled trials. Cite this article: Bone Joint J 2022;104-B(4):519-528.

The aim of this study was to evaluate the epidemiology and treatment of Perthes' disease of the hip.This was an anonymized comprehensive cohort study of Perthes' disease, with a nested consented cohort. A total of 143 of 144 hospitals treating children's hip disease in the UK participated over an 18-month period. Cases were cross-checked using a secondary independent reporting network of trainee surgeons to minimize those missing. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants.Overall, 371 children (396 hips) were newly affected by Perthes' disease arising from 63 hospitals, with a median of two patients (interquartile range 1.0 to 5.5) per hospital. The annual incidence was 2.48 patients (95% confidence interval (CI) 2.20 to 2.76) per 100,000 zero- to 14-year-olds. Of these, 117 hips (36.4%) were treated surgically. There was considerable variation in the treatment strategy, and an optimized decision tree identified joint stiffness and age above eight years as the key determinants for containment surgery. A total of 348 hips (88.5%) had outcomes to two years, of which 227 were in the late reossification stage for which a hip shape outcome (Stulberg grade) was assigned. The independent predictors of a poorer radiological outcome were female sex (odds ratio (OR) 2.27 (95% CI 1.19 to 4.35)), age above six years (OR 2.62 (95% CI (1.30 to 5.28)), and over 50% radiological collapse at inclusion (OR 2.19 (95% CI 0.99 to 4.83)). Surgery had no effect on radiological outcomes (OR 1.03 (95% CI 0.55 to 1.96)). PROMs indicated the marked effect of the disease on the child, which persisted at two years.Despite the frequency of containment surgery, we found no evidence of improved outcomes. There appears to be a sufficient case volume and community equipoise among surgeons to embark on a randomized clinical trial to definitively investigate the effectiveness of containment surgery. Cite this article: Bone Joint J 2022;104-B(4):510-518.

BACKGROUND:Routine measurement of gastric residual volume (GRV) to guide feeding in neonatal and paediatric intensive care is widespread. However, this practice is not evidence based and may cause harm. As part of a feasibility study, we explored parent and practitioner views on the acceptability of a trial comparing GRV measurement or no GRV measurement.METHODS:A mixed-methods study involving interviews and focus groups with practitioners and interviews with parents with experience of tube feeding in neonatal and/or paediatric intensive care. A voting system recorded closed question responses during practitioner data collection, enabling the collection of quantitative and qualitative data. Data were analysed using thematic analysis and descriptive statistics.RESULTS:We interviewed 31 parents and nine practitioners and ran five practitioner focus groups (n=42). Participants described how the research question was logical, and the intervention would not be invasive and potential benefits of not withholding the child's feeds. However, both groups held concerns about the potential risk of not measuring GRV, including delayed diagnosis of infection and gut problems, increased risk of vomiting into lungs and causing discomfort or pain. Parent's views on GRV measurement and consent decision making were influenced by their views on the importance of feeding in the ICU, their child's prognosis and associated comorbidities or complications.CONCLUSIONS:The majority of parents and practitioners viewed the proposed trial as acceptable. Potential concerns and preferences were identified that will need careful consideration to inform the development of the proposed trial protocol and staff training.

Background People with cystic fibrosis are susceptible to pulmonary infection with Pseudomonas aeruginosa. This may become chronic and lead to increased mortality and morbidity. If treatment is commenced promptly, infection may be eradicated through prolonged antibiotic treatment. Objective To compare the clinical effectiveness, cost-effectiveness and safety of two eradication regimens. Design This was a Phase IV, multicentre, parallel-group, randomised controlled trial. Setting Seventy UK and two Italian cystic fibrosis centres. Participants Participants were individuals with cystic fibrosis aged > 28 days old who had never had a P. aeruginosa infection or who had been infection free for 1 year. Interventions Fourteen days of intravenous ceftazidime and tobramycin or 3 months of oral ciprofloxacin. Inhaled colistimethate sodium was included in both regimens over 3 months. Consenting patients were randomly allocated to either treatment arm in a 1 : 1 ratio using simple block randomisation with random variable block length. Main outcome measures The primary outcome was eradication of P. aeruginosa at 3 months and remaining free of infection to 15 months. Secondary outcomes included time to reoccurrence, spirometry, anthropometrics, pulmonary exacerbations and hospitalisations. Primary analysis used intention to treat (powered for superiority). Safety analysis included patients who had received at least one dose of any of the study drugs. Cost-effectiveness analysis explored the cost per successful eradication and the cost per quality-adjusted life-year. Results Between 5 October 2010 and 27 January 2017, 286 patients were randomised: 137 patients to intravenous antibiotics and 149 patients to oral antibiotics. The numbers of participants achieving the primary outcome were 55 out of 125 (44%) in the intravenous group and 68 out of 130 (52%) in the oral group. Participants randomised to the intravenous group were less likely to achieve the primary outcome; although the difference between groups was not statistically significant, the clinically important difference that the trial aimed to detect was not contained within the confidence interval (relative risk 0.84, 95% confidence interval 0.65 to 1.09; p = 0.184). Significantly fewer patients in the intravenous group (40/129, 31%) than in the oral group (61/136, 44.9%) were hospitalised in the 12 months following eradication treatment (relative risk 0.69, 95% confidence interval 0.5 to 0.95; p = 0.02). There were no clinically important differences in other secondary outcomes. There were 32 serious adverse events in 24 participants [intravenous: 10/126 (7.9%); oral: 14/146 (9.6%)]. Oral therapy led to reductions in costs compared with intravenous therapy (–£5938.50, 95% confidence interval –£7190.30 to –£4686.70). Intravenous therapy usually necessitated hospital admission, which accounted for a large part of this cost. Limitations Only 15 out of the 286 participants recruited were adults – partly because of the smaller number of adult centres participating in the trial. The possibility that the trial participants may be different from the rest of the cystic fibrosis population and may have had a better clinical status, and so be more likely to agree to the uncertainty of trial participation, cannot be ruled out. Conclusions Intravenous antibiotics did not achieve sustained eradication of P. aeruginosa in a greater proportion of cystic fibrosis patients. Although there were fewer hospitalisations in the intravenous group during follow-up, this confers no advantage over the oral therapy group, as intravenous eradication frequently requires hospitalisation. These results do not support the use of intravenous antibiotics to eradicate P. aeruginosa in cystic fibrosis. Future work Future research studies should combine long-term follow-up with regimens to reduce reoccurrence after eradication. Trial registration Current Controlled Trials ISRCTN02734162 and EudraCT 2009-012575-10. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 65. See the NIHR Journals Library website for further project information.

OBJECTIVE:Cyclophosphamide (CYC) is used in clinical practice off-label for the induction of remission in childhood polyarteritis nodosa (PAN). Mycophenolate mofetil (MMF) might offer a less toxic alternative. This study was undertaken to explore the relative effectiveness of CYC and MMF treatment in a randomized controlled trial (RCT). METHODS:This was an international, open-label, Bayesian RCT to investigate the relative effectiveness of CYC and MMF for remission induction in childhood PAN. Eleven patients with newly diagnosed childhood PAN were randomized (1:1) to receive MMF or intravenous CYC; all patients received the same glucocorticoid regimen. The primary end point was remission within 6 months while compliant with glucocorticoid taper. Bayesian distributions for remission rates were established a priori for MMF and CYC by experienced clinicians and updated to posterior distributions on trial completion. RESULTS:Baseline disease activity and features were similar between the 2 treatment groups. The primary end point was met in 4 of 6 patients (67%) in the MMF group and 4 of 5 patients (80%) in the CYC group. Time to remission was shorter in the MMF group compared to the CYC group (median 7.1 weeks versus 17.6 weeks). No relapses occurred in either group within 18 months. Two serious infections were found to be likely linked to MMF treatment. Physical and psychosocial quality-of-life scores were superior in the MMF group compared to the CYC group at 6 months and 18 months. Combining the prior expert opinion with results from the present study provided posterior estimates of remission of 71% for MMF (90% credibility interval [90% CrI] 51, 83) and 75% for CYC (90% CrI 57, 86). CONCLUSION:The present results, taken together with prior opinion, indicate that rates of remission induction in childhood PAN are similar with MMF treatment and CYC treatment, and MMF treatment might be associated with better health-related quality of life than CYC treatment.

Introduction There is widespread variation in the management of rare orthopaedic disease, in a large part owing to uncertainty. No individual surgeon or hospital is typically equipped to amass sufficient numbers of cases to draw robust conclusions from the information available to them. The programme of research will establish the British Orthopaedic Surgery Surveillance (BOSS) Study; a nationwide reporting structure for rare disease in orthopaedic surgery. Methods The BOSS Study is a series of nationwide observational cohort studies of pre-specified orthopaedic disease. All relevant hospitals treating the disease are invited to contribute anonymised case details. Data will be collected digitally through REDCap, with an additional bespoke software solution used to regularly confirm case ascertainment, prompt follow-up reminders and identify potential missing cases from external sources of information (i.e. national administrative data). With their consent, patients will be invited to enrich the data collected by supplementing anonymised case data with patient reported outcomes. The study will primarily seek to calculate the incidence of the rare diseases under investigation, with 95% confidence intervals. Descriptive statistics will be used to describe the case mix, treatment variations and outcomes. Inferential statistical analysis may be used to analyze associations between presentation factors and outcomes. Types of analyses will be contingent on the disease under investigation. Discussion This study builds upon other national rare disease supporting structures, particularly those in obstetrics and paediatric surgery. It is particularly focused on addressing the evidence base for quality and safety of surgery, and the design is influenced by the specifications of the IDEAL collaboration for the development of surgical research.

Background: The routine measurement of gastric residual volume to guide the initiation and delivery of enteral feeding is widespread in paediatric intensive care and neonatal units, but has little underlying evidence to support it. Objective: To answer the question: is a trial of no gastric residual volume measurement feasible in UK paediatric intensive care units and neonatal units? Design: A mixed-methods study involving five linked work packages in two parallel arms: neonatal units and paediatric intensive care units. Work package 1: a survey of units to establish current UK practice. Work package 2: qualitative interviews with health-care professionals and caregivers of children admitted to either setting. Work package 3: a modified two-round e-Delphi survey to investigate health-care professionals’ opinions on trial design issues and to obtain consensus on outcomes. Work package 4: examination of national databases to determine the potential eligible populations. Work package 5: two consensus meetings of health-care professionals and parents to review the data and agree consensus on outcomes that had not reached consensus in the e-Delphi study. Participants and setting: Parents of children with experience of ventilation and tube feeding in both neonatal units and paediatric intensive care units, and health-care professionals working in neonatal units and paediatric intensive care units. Results: Baseline surveys showed that the practice of gastric residual volume measurement was very common (96% in paediatric intensive care units and 65% in neonatal units). Ninety per cent of parents from both neonatal units and paediatric intensive care units supported a future trial, while highlighting concerns around possible delays in detecting complications. Health-care professionals also indicated that a trial was feasible, with 84% of staff willing to participate in a trial. Concerns expressed by junior nurses about the intervention arm of not measuring gastric residual volumes were addressed by developing a simple flow chart and education package. The trial design survey and e-Delphi study gained consensus on 12 paediatric intensive care unit and nine neonatal unit outcome measures, and identified acceptable inclusion and exclusion criteria. Given the differences in physiology, disease processes, environments, staffing and outcomes of interest, two different trials are required in the two settings. Database analyses subsequently showed that trials were feasible in both settings in terms of patient numbers. Of 16,222 children who met the inclusion criteria in paediatric intensive care units, 12,629 stayed for > 3 days. In neonatal units, 15,375 neonates < 32 weeks of age met the inclusion criteria. Finally, the two consensus meetings demonstrated ‘buy-in’ from the wider UK neonatal communities and paediatric intensive care units, and enabled us to discuss and vote on the outcomes that did not achieve consensus in the e-Delphi study. Conclusions and future work: Two separate UK trials (one in neonatal units and one in paediatric intensive care units) are feasible to conduct, but they cannot be combined as a result of differences in outcome measures and treatment protocols, reflecting the distinctness of the two specialties. Trial registration: Current Controlled Trials ISRCTN42110505. Funding: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 23. See the NIHR Journals Library website for further project information.

MethodsTwo separate cross-sectional surveys were developed by the study team, one for PICUs and one for NNUs, in REDCap, 1 an online electronic data-capture tool. The surveys were tested for clarity and face validity on clinicians who did not go on to respond to the final surveys. Minor wording adjustments were made to improve clarity, then the surveys were tested again within the study team. Ethics approval for the surveys was provided by the University of the West of England (reference HAS. 18.04. 144). The Paediatric Intensive Care Society (PICS) Study Group also reviewed and endorsed the PICU survey, as did the Neonatal Nutrition Network.

Tume LN, Woolfall K, Arch B, et al. Routine gastric residual volume measurement to guide enteral feeding in mechanically ventilated infants and children: the GASTRIC feasibility study. Southampton (UK): NIHR Journals Library; 2020 May.(Health Technology Assessment, No. 24.23.)

Study designWork package 2 was a mixed-method study involving interviews with parents with relevant PICU or NNU experience, as well as focus groups and interviews with NNU and PICU health-care professionals (HCPs), including nurses, doctors, surgeons and dietitians.Objectives

Aims Slipped capital femoral epiphysis (SCFE) is one of the most common hip diseases of adolescence that can cause marked disability, yet there is little robust evidence to guide treatment. Fundamental aspects of the disease, such as frequency, are unknown and consequently the desire of clinicians to undertake robust intervention studies is somewhat prohibited by a lack of fundamental knowledge. Methods The study is an anonymized nationwide comprehensive cohort study with nested consented within the mechanism of the British Orthopaedic Surgery Surveillance (BOSS) Study. All relevant hospitals treating SCFE in England, Scotland, and Wales will contribute anonymized case details. Potential missing cases will be cross-checked against two independent external sources of data (the national administrative data and independent trainee data). Patients will be invited to enrich the data collected by supplementing anonymized case data with patient-reported outcome measures. In line with recommendations of the IDEAL Collaboration, the study will primarily seek to determine incidence, describe case mix and variations in surgical interventions, and explore the relationships between baseline factors (patients and types of interventions) and two-year outcomes. Discussion This is the first disease to be investigated using the BOSS Study infrastructure. It provides a robust method to determine the disease frequency, and a large unbiased sample of cases from which treatment strategies can be investigated. It may form the basis for definitive robust intervention studies or, where these are demonstrated not to be feasible, this may be the most robust cohort study.

AimTo gain meaningful PICU and NNU parents’ perspectives and input into a future GASTRIC trial.

Objective Despite little evidence, the practice of routine gastric residual volume (GRV) measurement to guide enteral feeding in neonatal units is widespread. Due to increased interest in this practice, and to examine trial feasibility, we aimed to determine enteral feeding and GRV measurement practices in British neonatal units.Design and setting An online survey was distributed via email to all neonatal units and networks in England, Scotland and Wales. A clinical nurse, senior doctor and dietitian were invited to collaboratively complete the survey and submit a copy of relevant guidelines.Results 95/184 (51.6%) approached units completed the survey, 81/95 (85.3%) reported having feeding guidelines and 28 guidelines were submitted for review. The majority of units used intermittent (90/95) gastric feeds as their primary feeding method. 42/95 units reported specific guidance for measuring and interpreting GRV. 20/90 units measured GRV before every feed, 39/90 at regular time intervals (most commonly four to six hourly 35/39) and 26/90 when felt to be clinically indicated. Most units reported uncertainty on the utility of aspirate volume for guiding feeding decisions; 13/90 reported that aspirate volume affected decisions ‘very much’. In contrast, aspirate colour was reported to affect decisions ‘very much’ by 37/90 of responding units. Almost half, 44/90, routinely returned aspirates to the stomach.Conclusions Routine GRV measurement is part of standard practice in British neonatal units, although there was inconsistency in how frequently to measure or how to interpret the aspirate. Volume was considered less important than colour of the aspirate.

BACKGROUND Choosing trial outcome measures is important. When outcomes are not clinically relevant or important to parents/patients, trial evidence is less likely to be implemented into practice. This study aimed to determine optimal outcome measures for a trial of no routine gastric residual volume (GRV) measurement in critically ill children. METHODS A mixed-methods approach was used: a focused literature review, parent and clinician interviews, a modified 2-round Delphi, and a stakeholder consensus meeting. RESULTS The review generated 13 outcomes. Fourteen pediatric intensive care unit (PICU) parents proposed 3 additional outcomes; these 16 were then rated by 28 clinicians in Delphi round 1. Six further outcomes were proposed, and 22 outcomes were rated in the second round. No items were voted "consensus out." The 18 "no-consensus" items were voted in a face-to-face meeting by 30 participants. The final 12 outcome measures were time to reach energy targets, ventilator-associated pneumonia, vomiting, time enteral feeds withheld per 24 hours, necrotizing enterocolitis, length of invasive ventilation, PICU length of stay, mortality, change in weight and markers of feed intolerance (parenteral nutrition administered), feed formula altered, and change to postpyloric feeds all secondary to feed intolerance. CONCLUSION We have identified 12 outcomes for a trial of no GRV measurement through a multistage process, seeking views of parents and clinicians.

Aims and objectivesTo determine potential patient recruitment numbers based on inclusion and exclusion criteria and, when these data are collected, to obtain summary statistics for potential primary and secondary outcomes identified by consensus from WP 3.

Aims and objectivesTo investigate PICU and NNU HCPs’ opinions on issues regarding a potential trial of GRV compared with no GRV measurement, including willingness to randomise and inclusion and exclusion criteria, and to gain consensus on potential primary and secondary outcome measures.

Background Routine measurement of gastric residual volume to guide feeding is widespread in neonatal units but not supported by high-quality evidence. Outcome selection is critical to trial design. Objective To determine optimal outcome measures for a trial of not routinely measuring gastric residual volume in neonatal care. Design A focused literature review, parent interviews, modified two-round Delphi survey and stakeholder consensus meeting. Participants Sixty-one neonatal healthcare professionals participated in an eDelphi survey; 17 parents were interviewed. 19 parents and neonatal healthcare professionals took part in the consensus meeting. Results Literature review generated 14 outcomes, and parent interviews contributed eight additional outcomes; these 22 outcomes were then ranked by 74 healthcare professionals in the first Delphi round where four further outcomes were proposed; 26 outcomes were ranked in the second round by 61 healthcare professionals. Five outcomes were categorised as ‘consensus in’, and no outcomes were voted ‘consensus out’. ‘No consensus’ outcomes were discussed and voted on in a face-to-face meeting by 19 participants, where four were voted ‘consensus in’. The final nine consensus outcomes were: mortality, necrotising enterocolitis, time to full enteral feeds, duration of parenteral nutrition, time feeds stopped per 24 hours, healthcare-associated infection; catheter-associated bloodstream infection, change in weight between birth and neonatal discharge and pneumonia due to milk aspiration. Conclusions and relevance We have identified outcomes for a trial of no routine measurement of gastric residual volume to guide feeding in neonatal care. This outcome set will ensure outcomes are important to healthcare professionals and parents.

Aims and objectivesTo bring together key stakeholders in each specialty, including national societies, parent groups, as well as HCPs and triallists, to:

OBJECTIVESDespite little evidence, the practice of routine measurement of gastric residual volume to guide both the initiation and delivery of enteral feeding in PICUs is widespread internationally. In light of increased scrutiny of the evidence surrounding this practice, and as part of a trial feasibility study, we aimed to determine enteral feeding and gastric residual volume measurement practices in U.K. PICUs.DESIGNAn online survey to 27 U.K. PICUs.SETTINGU.K. PICUs.SUBJECTSA clinical nurse, senior doctor, and dietician were invited to collaboratively complete one survey per PICU and send a copy of their unit guidelines on enteral feeding and gastric residual volume.INTERVENTIONSNone.MEASUREMENT AND MAIN RESULTSTwenty-four of 27 units (89%) approached completed the survey. Twenty-three units (95.8%; 23/24) had written feeding guidelines, and 19 units (19/23; 83%) sent their guidelines for review. More units fed continuously (15/24; 62%) than intermittently (9/24; 37%) via the gastric route as their primary feeding method. All but one PICU routinely measured gastric residual volume, regardless of the method of feeding. Eighteen units had an agreed definition of feed tolerance, and all these included gastric residual volume. Gastric residual volume thresholds for feed tolerance were either volume based (mL/kg body weight) (11/21; 52%) or a percentage of the volume of feed administered (6/21; 29%). Yet only a third of units provided guidance about the technique of gastric residual volume measurement.CONCLUSIONSRoutine gastric residual volume measurement is part of standard practice in U.K. PICUs, with little guidance provided about the technique which may impact the accuracy of gastric residual volume. All PICUs that defined feed tolerance included gastric residual volume in the definition. This is important to know when proposing a standard practice arm of any future trial of no-routine gastric residual volume measurement in critically ill children.