BLOOD VOLUME MEASUREMENTS IN THE NEONATAL LAMB: VALIDATION OF A METHOD USING [⁵¹Cr]‐LABELLED RED CELLS

Abstract

1. The reproducibility of blood volume measurements, using [51Cr]-labelled red blood cells (RBC) was tested in three lambs, 79-89 days of age, and the accuracy was tested in eight lambs, 83 +/- 0.4 days of age, in which blood volume was measured simultaneously by [51Cr]-RBC and [125I]-gamma globulin plus haematocrit (hct). 2. The blood volumes (mean +/- s.e.) of the three lambs, on four occasions, were 64.5 +/- 2.5, 68.8 +/- 2.9 and 63.9 +/- 3.7 mL/kg, respectively, and the coefficients of variation were 7.8, 8.6 and 11.6%, respectively. 3. The mean blood volume of eight lambs was 60.9 +/- 3.3 mL/kg by [51Cr]-RBC, and 60.8 +/- 2.4 mL/kg from plasma volume and hct. These were not statistically different. 4. Arterial hct was 31.2 +/- 0.5%, which was not statistically different from the whole body hct of 31.2 +/- 2.6%. 5. It is concluded that [51Cr]-RBC can be used to measure accurate and reproducible blood volumes in lambs.

Protective effect of prenatal water restriction on offspring cardiovascular homeostasis in response to hemorrhage

“…After the 2-h basal period, lambs were continuously hemorrhaged to 30% of estimated blood volume over a 60-min period at a rate of 0.5% of estimated blood volume per minute. Blood volume was estimated to be 75 ml/kg body wt on the basis of published information (18,32) and measured body weights for each lamb. During the basal period, 1.0-ml lamb blood samples (30 and 60 min) were replaced with an equal volume of heparinized maternal blood withdrawn before each experiment and filtered through a 20-m antimicrobial filter.…”

Postoperative complications in a lamb after major surgery

“…However, aggressive fluid therapy with crystalloids, followed by colloid and whole fresh maternal blood was unsuccessful. Given that the infusion of 860 mL should have increased its effective circulating blood volume (ECBV) by 30% ‐ assuming an ECBV of 7% body mass (Moritz et al. 1994) ‐ the absence of response should have prompted the search for an alternative diagnosis, or forced the conclusion of continuing volume losses.…”