[Colloid substitutes and hematocrit measurement by micromethods].
A study was carried out to determine whether centrifugation and resistivity were reliable methods for measuring haematocrit of blood diluted with dextran or gelatin. The values obtained with the minicentrifuge Compur M 1100 (Bayer) (group 2) and with the Stat-Crit (Fumouze) (group 3) were compared with those obtained with the reference method (Coulter counter Model S + 2, Coultronics) (group 1). The study included 10 healthy subjects, aged 21 to 43 years. In each, sodium, potassium, chloride and protein concentrations were determined. Two further 10 ml blood samples were taken to be diluted with increasing amounts of either a fluid modified gelatin (Plasmion) or a dextran 40 (Piasmacair). The dilutions carried out were 0, 10, 20, 30, 40 and 50%. For each one, the haematocrit was measured using all three methods. The values obtained with undiluted blood were similar with the three methods. However, when blood was diluted with a dextran, haematocrit values were underestimated, whatever method was used, but by no more than 5% (difference not statistically significant). The result was the same with the centrifugation method for blood diluted with gelatin. On the other hand, values obtained with the resistivity technique for these samples were underestimated up to 15.5% (50% dilution; p less than 0.05). This was due to the negative electric charge of the gelatin, which lowered the haematocrit value in proportion to the concentration of gelatin. Although the technique is easier than centrifugation, measuring haematocrit with a resistivity method should be avoided in patients receiving a fluid modified gelatin.
Vedrinne
J M
JM
Département d'Anesthésie-Réanimation IV, Hôpital Edouard-Herriot, Lyon.
Gentilhomme
O
O
Bussery
D
D
Hoen
J P
JP
Lasne
Y
Y
Motin
J
J
D001774:Blood Chemical Analysis; D002498:Centrifugation / Q000379:methods; D003102:Colloids; D006400:Hematocrit / Q000379:methods*; D006438:Hemodilution / Q000379:methods*; D006801:Humans; D008832:Microchemistry; D010952:Plasma Substitutes
D003102:Colloids; D010952:Plasma Substitutes