Hemodynamic and biochemical effects of intravenous versus oral fluids in healthy volunteers – A protocol for a randomized crossover trial

Introduction Intravenous fluid therapy is widely used to manage critically ill patients, addressing hypotension, hypovolemia, reduced urinary output etc. However, its effects on mean arterial pressure (MAP) and cardiac output (CO) are often short-lived. Oral fluid intake, a less invasive alternative, may produce more sustained effects, but evidence is limited. Methods This Phase 1, single-center, randomized controlled crossover trial will include 20 healthy participants. Each participant will receive 1 liter of tap water (8–10°C) for oral intake over 10 minutes or 1 liter of Ringer’s lactate (22°C) intravenously at 100 mL/min. After a 24-hour washout period, participants will switch to the alternate intervention. The primary outcome is the change in MAP 30 minutes after the start of fluid administration. Secondary outcomes include changes in CO, systemic vascular resistance index, stroke volume, and serum catecholamine levels. Discussion This study aims to provide new insights into the hemodynamic and biochemical effects of fluid therapy in healthy adults. By comparing the sustained effects of oral and intravenous fluid treatment, the results could improve patient care by reducing hospital admissions and healthcare costs. Trial Registration Number 2024-519656-85-00