The goal of this randomized clinical feasibility trial is to determine whether oral fluid therapy can achieve prescribed fluid volumes as effectively as intravenous fluid therapy in adult patients admitted to the emergency department who require fluid treatment.

The main questions it aims to answer are:

Are patients receiving oral fluids equally likely to achieve the prescribed fluid volume compared with patients receiving intravenous fluids?

Is it feasible to conduct a randomized trial of oral versus intravenous fluid therapy in the emergency department, based on recruitment rate and protocol adherence?

Researchers will compare oral tap water administration with standard intravenous crystalloid therapy to assess whether oral fluids are non-inferior in achieving prescribed fluid volumes and to evaluate feasibility outcomes.

Participants will:

Be randomized to receive either oral tap water or intravenous crystalloid fluids during their stay in the emergency department

Receive a fluid volume and administration rate determined by the treating physician

Be monitored according to standard clinical practice during the emergency department stay

Have fluid intake, vital signs, and clinical outcomes recorded, with follow-up through routine health records up to 30 days after inclusion

Inclusion Criteria:

• Age 18 or above
• At least 1000 ml of crystalloid fluid therapy prescribed by the physician

Exclusion Criteria:

• Altered mental state prohibiting oral fluid intake (Glasgow Coma Scale ≤ 12)
• Pregnancy
• Oral fluids contraindicated (e.g. bowel obstruction)
• Severe hyponatremia (sodium <120 mEq/L)
• Requiring treatment in the intensive care unit

De-identified IPD available upon reasonable request, subject to approval and data protection regulations.

Data will be available upon reasonable request beginning after publication of the primary results and ending 5 years thereafter.

Access to de-identified individual participant data (IPD) and supporting documentation will be granted to qualified researchers upon reasonable request. Requests must include a written proposal describing the research question, planned analyses, and intended use of the data. Proposed analyses must be scientifically sound and consistent with the scope of the original study.

Requests will be reviewed by the study investigators to assess scientific merit, feasibility, and compliance with ethical approvals and data protection regulations. Where required, approval from relevant ethics committees or data protection authorities must be obtained prior to data access.

Data sharing will be subject to the execution of a data sharing agreement outlining the terms of use, data security requirements, and restrictions on onward sharing. Data will be provided in a secure format and access will be limited to the approved analyses.