Haematocrit values and blood viscosity in the newborn infant
Van der Elst, C.W.; Malan, A.F.; Heese, H.D.
South African Medical Journal 53(13): 494-496
1978
ISSN/ISBN: 0256-9574 PMID: 675400 Document Number: 128798
For 48 Cape Coloured and 3 African infants, mean haematocrit is given for venous cord blood of 10 normal infants born by caesarean section whose umbilical cord had been cut within 38 sec of birth, and for warmed and unwarmed heel blood from those and the 41 others at 12 h old and on the 2nd, 3rd and 4th days of life. Heel was warmed by placing the foot in water at 40 deg to 42 deg C for 5 min before sampling. There was a close relation between haematocrit in warmed but not unwarmed heel capillary blood and that in central venous blood, which is often difficult to obtain. Blood was considered to be hyperviscous for 31% of infants with unwarmed heel haematocrit of 70% or over, for 71% of infants with warmed heel haematocrit 65% or over, and 81% of those with 68% or over, and 100% of infants with central venous haematorcit 65% or over. Haematocrits should be measured with uniform site, method and time of sampling; a delay of 5 min in clamping the cord can increase blood volume by 61% and increase the haematocrit. Warmed heel haematocrit may be used in screening for polycythaemia.