Submitted on March 8, 2005
Accepted on July 11, 2005
EXTREME HEMODILUTION WITH PEG-HEMOGLOBIN VS. PEG-ALBUMIN
Pedro Cabrales1*, Amy G Tsai1, Robert M Winslow2, and Marcos Intaglietta1
1 La Jolla Bioengineering Institute, La Jolla, CA, USA; Bioengineering, University of California, San Diego, La Jolla, CA, USA
2 Sangart, Inc, San Diego, CA, USA; Bioengineering, University of California, San Diego, La Jolla, CA, USA
* To whom correspondence should be addressed. E-mail: pcabrales{at}ucsd.edu.
Isovolemic hemodilution to 11% systemic hematocrit (Hct) was performed in the hamster window chamber model, using 6% dextran 70 kDa (Dx 70) and 5% human serum albumin (HSA). Systemic and microvascular effects of these solutions were compared to polyethylene glycol (PEG) conjugated 5% albumin (MPA) and PEG-conjugated 4.2% hemoglobin (MP4). These studies were performed for the purpose of comparing systemic and microvascular responses of PEG vs. non-PEG plasma expanders, and similar oxygen carrying vs. non carrying blood replacement fluids. Mean arterial blood pressure (MAP) was statistically significantly reduced for all groups compared to baseline (P < 0.05), with HSA, MPA and MP4 higher than Dx 70 (P < 0.05). MP4 and MPA had a significantly higher cardiac index than HSA and Dx 70, in addition to a positive base excess. Microvascular blood flow and capillary perfusion were significantly higher for the PEG compounds compared with HSA and Dx 70. Intravascular pO2 for MP4 and MPA was higher in arterioles (P < 0.05) when compared to HSA and Dx 70, but there was no difference in either tissue or venular pO2 between groups. Total hemoglobin (Hb) in the MP4 group was 4.8 ± 0.4 g/dl, while the remaining groups had a range of 3.6 - 3.8 g/dl. The hemodilution results showed that PEG compounds maintained microvascular conditions with lower concentrations than conventional plasma expanders. Furthermore, microvascular oxygen delivery and extraction in the window chamber tissue were significantly higher for the PEG compounds. MP4 was significantly higher than MPA (P < 0.05) and was not statistically different from baseline, an effect due to the additional oxygen release to the tissue by the Hb MP4.
