Radiological contrast media

1. This author believes that the present evidence (water shifts and vasodilatation) strongly indicates that low osmolality is probably the main advantage of the new contrast media. 2. Arteriographic adverse reactions (pain, vasodilatation) are less marked with the contrast medium of the lowest osmolality--i.e. ionic ioxaglate salts. 3. Minor adverse reactions (nausea and vomiting) are less marked with some non-ionic media (e.g. iohexol, iopamidol) than with ioxaglate but there are no data concerning the relative incidence of severe reactions or fatalities. 4. Dr. Lasser's suggestion in 1987, that 12 hours of corticosteroid prophylaxis reduces the adverse reaction rate of intravenous HOCM to the rate of LOCM reactions, awaits confirmation. However, corticosteroid prophylaxis will not reduce the side effects due to hyperosmolality, e.g. vasodilation, hypervolemia, and pain (on arterial injection). 5. Unless and until the necessary finances are available, I suggest LOCM (costing 12 times the price of HOCM in Canada and America) be used on a selective and discriminatory basis in three groups of patients: those undergoing painful procedures (e.g. peripheral arteriography), those undergoing potentially dangerous procedures (e.g. spinal angiography, coronary angioplasty) for patients considered on account of their previous medical history (e.g. asthma, allergy, previous adverse reactions, cardiac failure) to be at greater risk than the normal population.