[Red cell substitutes: perfluorocarbon emulsions and hemoglobin solutions]

Abstract

Objective: To review the current data on perfluorocarbon (PFC) emulsions and haemoglobin (Hb) solutions.

Data sources: For this paper we analysed the literature using Medline search along with major review articles.

Data selection and extraction: The collected articles were reviewed and selected according to their quality and originality.

Data synthesis: PFCs are synthetic fluorinated hydrocarbons capable of dissolving, at increased FIO2, large amounts of oxygen. They deliver oxygen at tissular level, and are administered as emulsions containing particles of around 0.1 micron, reaching the smallest vessels. They are exhaled unchanged by the lungs within 7 days. The first clinically used PFC was Fluosol-DA 20%. Currently, Oxyfluor 40% and Oxygent 60% are under evaluation. PFCs are not true blood substitutes, but rather a means to support tissue oxygenation during extreme haemodilution. Solutions of free Hb do not require compatibility testing and are fully saturated with oxygen at ambient FIO2. Hb is either human, bovine or recombinant Hb. In order to maintain adequate intravascular half-life and affinity for oxygen, the Hb molecules are modified by internal cross-linking, polymerisation and encapsulation. After promising results using animal models, some of these modified Hb solutions are now undergoing phase III clinical trials. Among these, diaspirin cross-linked haemoglobin (DCLHb) has been tested in cardiac and orthopaedic surgery, as well as in trauma patients. The initial results of these multicentre trials are currently being analysed.