title: Improving cardiac function with new-generation plasma volume expanders.
abstract: BACKGROUND
  Plasma expander (PE) based on polyethylene glycol (PEG) conjugated to albumin has shown positive results maintaining blood volume during hemodilution and restoring blood volume during resuscitation from hemorrhagic shock. Polyethylene glycol conjugation to human serum albumin (HSA), PEG-HSA, increases size, weight, and colloidal osmotic pressure, with minor effects on solution viscosity.
  
  
  METHODS
  This study was designed to test the hypothesis that PEG-HSA (2 g/dL) produced by direct PEGylation chemistry improves cardiac function during 2 experimental models, (i) moderate hemodilution and (ii) resuscitation from hemorrhagic shock, compared with a conventional colloidal PE (Dextran 70 kd [Dx70], 6 g/dL). Cardiac function was studied using a miniaturized pressure volume conductance catheter implanted in the left ventricle and evaluated in terms of cardiac indices derived from the pressure volume measurements.
  
  
  RESULTS
  Polyethylene glycol-HSA increased cardiac output, stroke volume, and stroke work and decreased systemic vascular resistance compared with Dx70 in both experimental models. The improvements induced by PEG-HSA in cardiac function were sustained over the observation time. Polyethylene glycol-HSA cardiac mechanoenergetics changes are the result of increased energy transferred per stroke and decreased resistance of the vasculature connecting the heart. In summary, PEG-HSA decreased left ventricle ejection impedance.
  
  
  CONCLUSIONS
  Ejection of blood diluted with PEG-HSA presented a reduced load to the heart, increased contractile function, and lowered the energy consumed per unit volume compared with Dx70. Our results emphasize the importance of heart function as a parameter to be included in the evaluation changes induced by new PEs.
authors.affiliation: Department of Bioengineering, University of California-San Diego, La Jolla, CA 92093, USA.
authors.forename: Surapong
authors.initials: S
authors.lastname: Chatpun
authors.forename: Parimala
authors.initials: P
authors.lastname: Nacharaju
authors.forename: Pedro
authors.initials: P
authors.lastname: Cabrales
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001810:Blood Volume / Q000187:drug effects*; D006328:Cardiac Catheterization; D002302:Cardiac Output / Q000187:drug effects*; D006224:Cricetinae; D006438:Hemodilution / Q000379:methods*; D008297:Male; D008647:Mesocricetus; D010952:Plasma Substitutes / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000494:pharmacology*; D012151:Resuscitation / Q000379:methods; D012709:Serum Albumin / Q000494:pharmacology*; D012771:Shock, Hemorrhagic / Q000188:drug therapy*; D014655:Vascular Resistance / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects*
chemical_list: D010952:Plasma Substitutes; D012709:Serum Albumin; D011092:Polyethylene Glycols