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Blood Density Is Nearly Equal to Water Density: A Validation Study of the Gravimetric Method of Measuring Intraoperative Blood Loss.

Vitello DJ, Ripper RM, Fettiplace MR, Weinberg GL, Vitello JM - J Vet Med (2015)

Bottom Line: Results.Conclusions.The study confirmed that the measured density of blood is similar to water.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Jesse Brown VA Medical Center, University of Illinois at Chicago, 820 S. Damen Avenue, Chicago, IL 60612, USA.

ABSTRACT
Purpose. The gravimetric method of weighing surgical sponges is used to quantify intraoperative blood loss. The dry mass minus the wet mass of the gauze equals the volume of blood lost. This method assumes that the density of blood is equivalent to water (1 gm/mL). This study's purpose was to validate the assumption that the density of blood is equivalent to water and to correlate density with hematocrit. Methods. 50 µL of whole blood was weighed from eighteen rats. A distilled water control was weighed for each blood sample. The averages of the blood and water were compared utilizing a Student's unpaired, one-tailed t-test. The masses of the blood samples and the hematocrits were compared using a linear regression. Results. The average mass of the eighteen blood samples was 0.0489 g and that of the distilled water controls was 0.0492 g. The t-test showed P = 0.2269 and R (2) = 0.03154. The hematocrit values ranged from 24% to 48%. The linear regression R (2) value was 0.1767. Conclusions. The R (2) value comparing the blood and distilled water masses suggests high correlation between the two populations. Linear regression showed the hematocrit was not proportional to the mass of the blood. The study confirmed that the measured density of blood is similar to water.

No MeSH data available.


Related in: MedlinePlus

Graph correlating rat blood mass to blood hematocrit.
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Related In: Results  -  Collection


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fig1: Graph correlating rat blood mass to blood hematocrit.

Mentions: The masses of the 18 blood aliquots are recorded in Table 1. The average mass of the 50-microliter blood samples was 0.0489 ± 0.032 g with a range of 0.0445 g to 0.0512 g. Table 2 lists the masses of the 18 distilled water controls. The average mass of the 50-microliter water samples was 0.0492 g with a range from 0.0487 g to 0.0496 g. The average density of the blood samples was normalized to the average mass of the distilled water controls by dividing the two means to yield specific gravity and an adjusted mean blood density of 0.994 ± 0.032 g/mL. The average hematocrit of the blood samples was 40.3% (range 24%–48%). Figure 1 shows the mass of the 50 µL samples of blood as a function of hematocrit. The R2 value was 0.1767. Therefore, there was poor correlation between the hematocrits and the density of the blood samples. Populations were deemed fit for parametric testing but their variances were unequal by ANOVA (P < 0.00001). To account for this a Student's t-test with a Welch's correction was utilized to compare the blood and distilled water samples. The results yielded a P = 0.2269 and R2 = 0.03154. This analysis verifies the fact that the mass of the blood and water samples was not significantly different.


Blood Density Is Nearly Equal to Water Density: A Validation Study of the Gravimetric Method of Measuring Intraoperative Blood Loss.

Vitello DJ, Ripper RM, Fettiplace MR, Weinberg GL, Vitello JM - J Vet Med (2015)

Graph correlating rat blood mass to blood hematocrit.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4590883&req=5

fig1: Graph correlating rat blood mass to blood hematocrit.
Mentions: The masses of the 18 blood aliquots are recorded in Table 1. The average mass of the 50-microliter blood samples was 0.0489 ± 0.032 g with a range of 0.0445 g to 0.0512 g. Table 2 lists the masses of the 18 distilled water controls. The average mass of the 50-microliter water samples was 0.0492 g with a range from 0.0487 g to 0.0496 g. The average density of the blood samples was normalized to the average mass of the distilled water controls by dividing the two means to yield specific gravity and an adjusted mean blood density of 0.994 ± 0.032 g/mL. The average hematocrit of the blood samples was 40.3% (range 24%–48%). Figure 1 shows the mass of the 50 µL samples of blood as a function of hematocrit. The R2 value was 0.1767. Therefore, there was poor correlation between the hematocrits and the density of the blood samples. Populations were deemed fit for parametric testing but their variances were unequal by ANOVA (P < 0.00001). To account for this a Student's t-test with a Welch's correction was utilized to compare the blood and distilled water samples. The results yielded a P = 0.2269 and R2 = 0.03154. This analysis verifies the fact that the mass of the blood and water samples was not significantly different.

Bottom Line: Results.Conclusions.The study confirmed that the measured density of blood is similar to water.

View Article: PubMed Central - PubMed

Affiliation: Department of Anesthesiology, Jesse Brown VA Medical Center, University of Illinois at Chicago, 820 S. Damen Avenue, Chicago, IL 60612, USA.

ABSTRACT
Purpose. The gravimetric method of weighing surgical sponges is used to quantify intraoperative blood loss. The dry mass minus the wet mass of the gauze equals the volume of blood lost. This method assumes that the density of blood is equivalent to water (1 gm/mL). This study's purpose was to validate the assumption that the density of blood is equivalent to water and to correlate density with hematocrit. Methods. 50 µL of whole blood was weighed from eighteen rats. A distilled water control was weighed for each blood sample. The averages of the blood and water were compared utilizing a Student's unpaired, one-tailed t-test. The masses of the blood samples and the hematocrits were compared using a linear regression. Results. The average mass of the eighteen blood samples was 0.0489 g and that of the distilled water controls was 0.0492 g. The t-test showed P = 0.2269 and R (2) = 0.03154. The hematocrit values ranged from 24% to 48%. The linear regression R (2) value was 0.1767. Conclusions. The R (2) value comparing the blood and distilled water masses suggests high correlation between the two populations. Linear regression showed the hematocrit was not proportional to the mass of the blood. The study confirmed that the measured density of blood is similar to water.

No MeSH data available.


Related in: MedlinePlus