Long Island Jewish Medical Center
Division of Nuclear Medicine
New Hyde Park, NY

EVALUATION OF A RAPID, AUTOMATED
BLOOD VOLUME ANALYZER

Salil D. Sarkar, Chistopher J. Palestro and Kuldeep K. Bhargava

Presentation given at the Society of Nuclear Medicine Conference, June 6-10, 1999, Los Angeles, California

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Introduction: Rapid assessment of blood volume is critical in such situations as shock, preoperative state, hemodialysis and orthostatic hypotension. The blood hematocrit, a readily available parameter, is simply a measure of the ratio of red blood cells to plasma, i.e.; it can be normal if both red blood cells and plasma volumes are reduced and falsely 'low' in hemodilution. Clinical hemodynamic measurement including urine output, heart rate, mean arterial pressure and pulmonary wedge pressure, do not necessarily reflect the status of the total/peripheral blood volume. For these, reasons, the blood volume must be directly measured.

Combined measurement of both red blood cell (RBC) and plasma volumes using traditional tracer dilution techniques provides an accurate assessment of polycythemia. This approach, however, is time-consuming and not ideal in the acute clinical setting. In this paper, we evaluate a semiautomated system (Blood Volume Analyzer, Daxor Corporation, New York) for rapid assessment of blood volume. Results obtained by this system are compared with those using a traditional, validated 'manual' approach.

Results:

	RBC Volume (ml)			Plasma Volume (ml)			Total Blood Volume (ml)
	Manual	Auto	%D*	Manual	Auto	%D*	Manual	Auto	%D*
1	2116	2030	4	3542	3210	9	5658	5340	7
2	1871	1900	2	3094	3005	3	4965	4905	1
3	2253	2236	1	3802	3673	3	6055	5909	2
4	1335	1370	3	3601	3535	2	4936	4905	1
5	2470	2421	2	3906	3685	6	6376	6106	4
6	1958	1812	8	3306	2976	10	5264	5264	9

Both methods are done simultaneously in each individual.
* Difference in measured volumes between the two methods.

Conclusions:

1. The semiautomated analyzer provides blood volume estimates comparable to those determined by the manual method, with an average underestimation of 4% (range 1-9%).
2. Results are provided in less than half the time required for the manual method. Furthermore, the analyzer requires only modest technical skills. Therefore, it is ideally suited for clinical situations, including those arising after hours that may require prompt restoration of intravascular volume.
3. Further studies are warranted for the routine use of the analyzer in polycythmeia.