• synthetic;
  • colloids;
  • total;
  • protein;
  • total solids


Veterinary patients are treated with colloid solutions for plasma volume expansion and maintenance of plasma colloid oncotic pressure (COP). In practice COP is usually extrapolated from measurement of albumin, total protein, or refractometric total solids (TS) as an estimate of total protein. The objective of this study was to determine if refractometer readings accurately reflect levels of synthetic colloid in the blood. Serial dilutions of synthetic colloids Dextran 70 and hetastarch into 2.5% and 5% human serum albumin (HSA) were prepared, and COP and TS measurements were performed. Synthetic colloids were found to produce a significant increase in measured COP, without a significant change in refractometric TS readings. Measured COP correlated well with concentration of synthetic colloid. In clinical patients, treatment of decreased COP with synthetic colloids should be monitored by direct measurement of COP or by observing resolution of clinical signs of hypovolemia or edema. (Vet Emerg & Crit Care, 1998; 8: 21–26)