The purpose of this pilot study is to overcome the limited evidence on enteral fluid administration in intensive care medicine and to generate data for further hypothesis generation in an exploratory setting. This trial is a prospective, multicenter, randomized, parallel group, open-label study to compare the current standard of practice, the intravenous fluid administration, with a more physiological approach, the enteral fluid administration, in critically ill patients.

Introduction: The effectiveness and safety of enteral fluid administration in critically ill patients remains unclear. Existing evidence regarding this topic is scarce, but suggests that enteral fluid administration is a safe route of administration. To our knowledge no randomized controlled trial has been conducted investigating this topic.

Objectives: The aim of this pilot study is to gather evidence on the impact of enteral fluid replacement on clinical, laboratory and outcome parameters in intensive care patients in order to plan a subsequent larger randomized controlled trial. Clinical outcomes indices evaluated are regurgitation, thirst, serum sodium, mortality, length of mechanical ventilation arterial pressure, urinary volume, body weight, edema, intra-abdominal pressure), changes in bioimpedance spectroscopy-derived markers, fluid overload, renal function tests, liver function tests and SOFA-Scores.

Methods: The trial is a prospective, multicenter, randomized, parallel group, open-label study. Patients are going to be recruited and randomized at 3 separate internal medicine intensive care units in Vienna, Austria. A total of 64 patients will be recruited and randomized to receive enteral fluid administration via nasogastric tube or intravenous administration only. Daily visits and evaluation of clinical and radiological fluid status is performed by the attending physician. Regular study visits with Bioimpedance spectroscopy measurements (BIS) to evaluate fluid status are going to be performed

Results and conclusions: The ERI study will provide data on potential outcome parameters to plan a subsequent larger randomized control trial for patients receiving enteral fluid therapy in intensive care medicine.

Ethics and dissemination: The trial is performed in accordance with the Declaration of Helsinki. It subscribes to the principles outlined in the most recent version of the International Conference on Harmonization on Good Clinical Practice. Approval was obtained from the ethics committee of the Medical University of Vienna (EK number 1790/2020). The study has also been registered in a public clinical trial database (EudraCT Identifier Number 2018-002447-29, clinicaltrialsregister.eu).

• Inclusion criteria:

  • Patient intubated within the last 72h
  • Age >18 years
  • Expected required fluid volume may not exceed 4 mL/kg/h (permanently, during at least 24 hours).
  • Negative pregnancy test in female patients of childbearing potential
  • Informed consent. For patients that are temporarily unable to consent a
  • subsequent informed consent must be provided.

• Exclusion criteria:

  • Evidence of severe gastrointestinal disease defined as

    • Gastrointestinal Failure with > 3 symptoms (see below) or
    • Lactate >3mmol/L when mesenterial ischemia is a probable cause
    • Clinical signs of intra-abdominal hypertension and an increase of intra-abdominal pressure of >20 mmHg.

  • Patients who cannot receive early enteral nutrition due to conditions such as prone positioning in consequence of conditions such as acute respiratory distress syndrome

  • Pregnancy

  • Abdominal surgery in the last 3 months (unless all involved physicians, study investigators and caretaking doctors agree that the surgical event does not constitute a limitation for enteral fluid administration)

  • Postoperative patients with consecutive admission to ICU

  • Extracorporeal Kidney-Replacement Therapy before intubation

  • At the discretion of the Investigator

Symptoms of Gastrointestinal Failure:

• Absent bowel sounds
• Bowel distension
• Vomiting/regurgitation volume >500 ml
• GI bleeding
• Diarrhoea (liquid stool >3 times a day)
• Distended stomach on ultrasound examination.