Effects of polycythemia and hyperviscosity on cutaneous blood flow and transcutaneous PO2 and PCO2 in the neonate

Neonatal hyperviscosity syndrome is known to affect multiple organ systems. The effects of polycythemic hyperviscosity on cutaneous blood flow and transcutaneous PO2 and PCO2 were compared in ten term infants prior to and following correction of the hyperviscous state. Cutaneous blood flow was measured by the heat clearance method; transcutaneous PO2 and PCO2 were detected by a polarographic O2 cathode and a potentiometric pH-sensitive glass electrode, respectively. Whole blood viscosity was measured at five shear rates from 11.25/s to 225/s using a Wells-Brookfield viscometer. Following partial exchange transfusion with fresh frozen plasma, there was a significant decrease in arterial blood hematocrit from 62.7% +/- 5.9% to 48.4% +/- 4.8% (P less than .001) and in whole blood viscosity from 13.9 +/- 2.9 cps to 8.5 +/- 1.8 cps (P less than .001) at a shear rate of 11.25/s. The arterial and transcutaneous O2 and CO2 tensions were in the normal range in the hyperviscous state and remained unchanged following exchange transfusion. The static measure of cutaneous blood flow increased 36% from 208 +/- 54 mW to 283 +/- 75 mW (P less than .01) while the dynamic measure of cutaneous blood flow increased 38% to 41% (P less than .01). The lack of demonstrable cutaneous hypoxia and hypercapnia, despite a significant decrease in blood flow in the hyperviscous state, may be due to one or more factors.