The recruitment was much slower than expected and the COVID pandemic added new barriers to recruitment.

The investigators aim to assess whether ondansetron given at triage can reduce the number of patients requiring emergency department observation in children with acute gastroenteritis. The investigators will also assess the improvement of patient comfort and total length of stay

Background:

Acute gastroenteritis is one the most common cause of emergency room visits. Studies have demonstrated that ondansetron is effective in reducing vomiting in children with gastroenteritis and improve outcomes by decreasing intravenous rehydration and hospital admission of those patients. Giving ondansetron to children with suspected gastroenteritis immediately at triage could reduce the number of patients requiring observation in the emergency department after medical consultation and improve patients' outcomes.

Objective:

The aim of this study is to assess the effectiveness of triage-initiated administration of ondansetron for suspected gastroenteritis in the paediatric emergency department. The investigators aim to assess whether ondansetron given at triage can reduce the number of patients requiring observation in children with acute gastroenteritis. The investigators will also assess the improvement of patient comfort and total length of stay.

Methods:

This will be a randomized controlled trial performed in a tertiary paediatric emergency department. Participants will include all infants more than 8kg who present to the emergency department with at least four vomiting in the previous 24 hours and the last vomiting that occurred in the previous 2h. The intervention will consist of giving ondansetron at triage versus placebo. The primary outcome will be the number of patients requiring observation after medical consultation in both groups. Secondary objectives will be the number of episodes of vomiting after receiving the intervention, length of stay in the emergency department and the proportion of children who will return to a physician within 48 hours. The investigators will assess the improvement of patient comfort evaluated by parents according to a BARF (Baxter Animated Retching Face) Scale within the ondansetron group vs placebo. The primary analysis will be the comparison of the proportion of observation for the two groups. Based on a preliminary study of the currents children suffering from gastro-enteritis, it was estimated that the recruitment of 248 participants will provide a power of 90% to identify a 20% difference in the proportion of observed patients.

Inclusion Criteria:

• Children aged more than 6 months and weight ≥ 8kg
• At least 4 non-bilious, non-bloody vomiting in the preceding 24 hours
• The last vomiting occured less than 2 hours ago
• No other diagnostic more likely than gastroenteritis suspected by the nurse at triage.

Exclusion Criteria:

• Severe dehydration (based on poor capillary refill or hypotension)
• Underlying disease that could affect the assessment of hydration (such as renal failure or hypoalbuminemia)
• Bilious or bloody vomiting
• Bloody stool
• A history of abdominal surgery
• Allergy to ondansetron
• Long QT syndrome or major cardiac condition
• Previous enrolment in the study.
• Girl at risk of pregnancy (pubertal girl)
• Inability to obtain parental informed consent (language barrier, absence, etc.)