Further Note on the Enumeration of Blood Platelets and Red Blood Cells.

Abstract

In a previous communication, 1 a new method of blood platelet and red cell enumeration was proposed in which Ringer-Heparin solution was substituted for Hayem's solution as the diluent. In order to test the preliminary contention that the red blood cells may be counted in the Ringer-Heparin solution as accurately as with Hayem's solution, 75 parallel counts have since been made within 6 hours after the blood was taken. These included 24 counts upon 8 normal and pathological rabbits, 6 counts upon 1 normal and 2 anemic dogs, and 45 counts upon 31 normal and diseased humans, no material being omitted. The means of these parallel determinations are as follows: (1) Hayem's solution: 5,109,700 red blood cells per cmm. (2) Ringer-Heparin solution: 5,116,200 red blood cells per cmm. The standard error of the mean for the 75 counts was approximately the same in each case, that is, 175,000 cells. It may be concluded, therefore, that both methods gave identical results. Hemolysis or fading of the red blood cells with the use of the Ringer-Heparin solution did not occur in any instance either in the pipette or on the counting chamber.

Other useful points of technique noted since the first report include: (1) autoclaving of the stock Ringer's solution; (2) reduction of the NaHCO₃ in the standard Ringer's solution from 0.10 gm. to 0.05 gm. per 1000 cc.; (3) refrigeration of pipettes of diluted blood for delayed counting; (4) reduction of the amount of heparin used for blood counted within 3 hours after taking; (5) the necessity of a thorough mixture through vigorous shaking of the pipettes by hand or machine. It should be pointed out that Hayem's and other fixative solutions should not be used in pipettes employed for Ringer-Heparin solution since hemolysis may occur even after several thorough washings.