Should we use hypotonic or isotonic maintenance intravenous fluids in sick patients? Why a study in healthy volunteers will not provide the answer

Editor—Sick patients who are unable to ingest oral fluids usually receive i.v. maintenance fluid therapy (IVMFT). The main goal of IVMFT is to temporarily meet water, electrolyte and glucose needs pending a more sustainable (par)enteral solution for feeding and hydration. Despite routine application, IVMFT is often based on dogmatic principles rather than high quality empirical research.1 Furthermore, macro- and micronutrient deficiencies, fluid overload, hyperchloraemic acidosis and hyponatraemia have all been reported as potentially detrimental complications.