Osmolality (Hypertonicity)

 

Osmolality - The measure of the total number of particles in solution per kilogram of water (Ions/ml in solution).

 

A. Great biologic significance

B. Most adverse reactions to contrast result from the osmolality of the agent

B. Ionic contrast agents are HOCM

C. Nonionic contrast agents are typically LOCM

D. Considered to be the responsible factor for vasodilation, pain and flushed feeling

E. The newer non-ionic compounds, Isovue and Omnipaque, exhibit lower osmolality and consequently fewer adverse reactions due to decrease of ions/ml

 

Viscosity

Viscosity – A measure of the resistance of fluid to flow.

1. Measured by the amount of force required to move a liquid under standard conditions

2. The standard used is the force needed to move water at 200 C (680 F) and measured in centipoise (cp)

3. Viscosity is inversely proportional to temperature