Table 1.

Characteristics of included studies

Freedman 2011 [18]
Methods	Randomised controlled trial conducted in the emergency department of the Hospital for Sick Children, Toronto, Canada. Study period between December 2006 and April 2010
Study aim	To determine if rapid rather than standard intravenous rehydration results in improved hydration and clinical outcomes when administered to children with gastroenteritis.
Participants	Inclusion criteria: Age > 90 days; diagnosis of dehydration secondary to gastroenteritis and refractory to oral rehydration.
	Exclusion criteria: children weighing < 5 kg or > 33 kg, requiring for fluid restriction, had a suspected surgical condition, had a history of a severe chronic systemic disease, abdominal surgery, or bilious vomit, had hypotension, hypoglycaemia or hyperglycaemia, insurmountable language barrier or lack of telephone for follow up call.
Interventions	One hundred and twelve infants received 60 mL/kg of 0.9% saline over 60 min (rapid rehydration) and 114 children received 20 mL/kg over 60 min (standard rehydration).
Allocation	1:1
Outcomes	Primary: Rehydration defined as a score on the clinical dehydration scale of ≤1 two hours after the start of treatment.
	Secondary: Prolonged treatment – a composite measure defined as admission to an inpatient unit at the index visit or admission within 72 h of randomisation or a stay in the emergency department longer than 6 h after the start of treatment; score on a clinical dehydration scale; adequate oral fluid intake defined as consuming at least 5 mL/kg of liquid per 2 h time period; time to discharge defined as time between start of treatment and discharge from the emergency department of inpatient unit; repeat emergency department visit within 72 h; and attending physician’s comfort with discharge at two and four hours, reported on a 5-point Likert scale.
Nager 2008 [19]
Methods	Pilot randomised controlled convenience sample study in the emergency department of the Children Hospital in Los Angeles, USA
Study aim	To provide some evidence for our belief that the ultra protocol could be performed effectively with similar results as the standard hydrating method.
Participants	Ninety-two children aged 3 to 36 months
	Inclusion criteria: acute (< 7 days) complaints of vomiting and/or diarrhoea) and moderate dehydration and failure of oral rehydration.
	Exclusion criteria: severe dehydration, shock, suspected intussusception, appendicitis, mal-rotation, recent trauma, meningitis, or congestive heart failure or if any of these diagnoses appeared as the study progressed; chronic disease or significant laboratory abnormality including Na < 130 or > 150 mmol/L and/or K < 3.2 or > 5.5 mmol/L.
Interventions	50 mL/kg of normal saline IV administered for 1 h (ultra rapid IV hydration) or 50 mL/kg normal saline IV for 3 h (standard hydration)
Allocation	1:1
Outcomes	Efficacy of treatment by assessing Success and timing of rehydration, study failures (defined as requirement for admission), output (urine, emesis, stool) during the treatment phase, pre- and post treatment laboratory abnormalities, number of return visits, and whether serious complications occurred.
Azarfar 2014 [20]
Methods	Randomised controlled trial conducted in the emergency department in a tertiary centre (Tabriz children’s hospital) in Tabriz, North-West of Iran.
Objective	To evaluate the effect of rapid intra- venous rehydration to resolve vomiting in children with acute gastroenteritis.
Participants	Inclusion criteria: 150 Children with moderate dehydration or vomiting due to gastroenteritis who had not responded to oral rehydration therapy.
	Exclusion criteria: severe dehydration, shock, and hypotension, electrolyte abnormalities, none or mild dehydration.
Intervention	20-30 mL/kg of a crystalloid solution over either 2 h (intervention group) or 24 h (control group).
Allocation	1:1
Outcomes	Primary outcome: Resolution of vomiting in children receiving rapid intravenous rehydration.
	No secondary outcomes.