*6.1.1 Intravenous hydration*

Adequate hydration for patients performing CM-enhanced imaging studies was suggested approximately 40years ago [30]. The beneficial effects of hydration were initially reported in the early 1980s by studies that compared outcomes of hydrated patients with historical controls [60, 61]. These reports were supported by the first RCT in 1994, concluding that patients with chronic renal impairment benefit better from intravenous (0.45%) saline administration (for 12h before and 12h after angiography) in comparison with saline plus mannitol or furosemide [62]. Since then, multiple RCTs have assured the benefit of intravenous normal saline (0.9%) hydration that is started 12h preceding to 12h after CM injection [63–65] in the prevention against CIN over 0.45% saline [65] or a fluid bolus (300mL) during CM administration only [66]. The rate of infusion was reported as 1mL/kg/h [67]. CM safety committee endorse a regime of intravenous infusion of 1.0–1.5mL/kg/h for at least 6h before and after CM administration [68].
