硫酸銅法による比重判定時の血液静止位置の重要性

抄録

The Japanese Red Cross Blood Center routinely uses the copper sulfate (CS) method to exclude anemic blood donors, because of its simplicity, speed and minimal expense. With this method the level at which a drop of donor blood becomes stationary varies according to its specific gravity (SG). The CS method procedure is described in the AABB's technical Manual and in many papers, but the manner of interpretation of the stationary level is not specified.
The drop is delivered from about 1cm above the CS solution in a 100ml glass bottle (6cm high, 46mm in diameter) from an SG needle (Kawasumi, Japan). Momentum carries the drop 1 or 2cm below the surface, and it will then rise, become stationary, or continue to fall. We studied the method using stationary drops at only 4 levels: level A, 3.0cm below the surface; B, 1.5cm below; C, 1.0cm below; and D, 0.5cm below. The SG of these 4 blood samples were measured by pycnometer. The samples were of whole blood containing citrate-phosphate-dextrose (SG approximately 1.052). In Japan, the minimum condition for donors giving 200ml whole blood or undergoing plasmapheresis is hemoglobin (Hb)≥12.0g/dl or SG≥1.052. Temperature affects SG, which was measured at 30-32°C with an SG needle in a catheter probe (Terumo, Japan), and blood drop tests were done after incubation at 30°C. The CS solution (d²⁰₂₀=1.0521) was warmed from 15 to 35°C.
Pycnometer values for blood SG varied according to the drop level in the CS solution and to the solution temperature, the average difference between positions A and D at 20°C being 0.0014. At 20°C, a drop in the D position, 5mm below the surface, had the same SG as the solution (1.0522±0.0002, n=3). Routine screening of position D showed that only 5 percent of eligible donors would have been rejected for low Hb. Although the CS method has a higher donor rejection rate than the Hb procedure, its rejection rate varied with the drop stationary level.