Because intravenous fat emulsions are now frequently employed as nutritional supplements and because a relationship between increased viscosity and thrombosis has been suggested,1 it appeared important to determine whether these substances increase blood viscosity in human beings. Swank 2 has demonstrated marked changes in the viscosity of blood following intravenous administration of lipids to dogs and after ingestion of large quantities of fat by hamsters.3 His studies were not extended to man. In order to assess the effect of injected fat emulsions on the viscosity of circulating blood, an in vivo technique of measuring viscosity 4 was utilized.
The method of determining blood viscosity employed in the present study is based on Poiseuille's law that during laminar flow of a homogeneous fluid in a tube of constant diameter the frictional loss bears a linear relationship to the volumetric rate of flow and is independent of the vessel
SHEARN MA, GOUSIOS A. Effect of Intravenous Fat Emulsions on Human Blood Viscosity. Arch Intern Med. 1960;106(5):619–621. doi:10.1001/archinte.1960.03820050031006