Contrast Media Osmolality and Plasma Volume Changes

Abstract

A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media.

Hemodynamic effects of iodixanol and iohexol during ventriculography in patients with compromised left ventricular function

“…The late tendency for increased cardiac output is in agreement with data from other trials [2,34,38], and is also consistent with an increased blood volume, because the peripheral resistance had returned to baseline at these time points. In one trial in urography, plasma volume was shown to increase maximally 8% at 3-5 min after injection of iohexol [41]. The small, early decrease in peak negative dP/dt is similar to that reported by others [35,37].…”

The non-ionic dimers: a new class of contrast agents

“…Their lower osmolalities may offer image-quality improvements in intravenous digital subtraction angiography (DSA) as a result of lesser dilution of the contrast-agent bolus in the central blood volume (Hine et al, 1985).…”

Digital Angiography—Myth and Reality

“…It can be minimised by placing the catheter as far centrally as possible, for example into the right atrium. Furthermore, it appears to be the case that the contrast agent itself, by a combination of osmotic effects and direct action on blood vessels, expands the central blood volume and produces a further deterioration in the contrast density-time curve and image quality (Hine, Lui & Dawson 1985, Burbank 1983). The use of a low osmolality contrast agent will reduce these effects.…”