The SMART trial compared balanced crystalloids with 0.9% saline for intravenous fluid administration in more than 15,000 critically ill adults. The primary outcome was a composite of major adverse kidney events within 30 days, including death, new renal-replacement therapy or persistent renal dysfunction. The balanced-crystalloid strategy produced a modestly lower rate of this composite outcome than saline. The absolute difference was small, but the direction of effect was consistent with the biologic concern that high chloride exposure from saline may contribute to renal and acid-base abnormalities. SMART is clinically valuable because fluid choice is often repeated many times over an ICU admission; a small difference per litre can become meaningful when accumulated across large volumes and prolonged care. The trial does not mean that saline is universally harmful or that balanced solutions are mandatory in every circumstance. Rather, it supports considering balanced crystalloids as a default option when there is no specific reason to use saline. In patients at high risk of kidney injury, the cumulative chloride burden and total fluid exposure deserve particular attention. SMART also reinforces a broader critical-care message: seemingly simple supportive therapies can influence important outcomes when delivered at scale.