Abstract
We studied the effect of increasing hematocrit(Hct) on the pulmonary and systemic circulations, and systemic O2 transport(SOT) in the presence of a large QLR. Isovolemic ExTx designed to raise Hct but keep blood volume constant was performed during cardiac catheterization on 8 infants(ave age=7 wk, wt=3.8 kg) with large QLR at the ventricular level. Hct, vascular pressures, O2 uptake, and O2 saturations were measured prior to and after ExTx. Blood flows(L min-1M-2) and vascular resistances(Wood units) were calculated. With ExTx, Hct increased with no change in mean atrial pressures. As shown in the table, both pulmonary and systemic blood flows(Qp,Qs) fell, however SOT(m1 O2 min-1M-2) increased despite the decline in Qs. After ExTx pulmonary(Rp) and systemic(Rs) vascular resistances increased, but Rp more than Rs as shown by the rise in Rp/Rs. These resistance changes are consistent with the expected increase in vicosity, but the disparity in effect may be due to concommittant alterations in the cross sectional area of the respective vascular beds. Thus an increase in Hct may provide an important adjunct to the acute management of a large QLR by reducing the shunt flow while maintaining or improving SOT.
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Hellenbrand, W., Lister, G., Kleinman, C. et al. 150 EFFECTS OF EXCHANGE TRANSFUSION(ExTx) ON THE PULMONARY AND SYSTEMIC CIRCULATIONS IN LEFT-TO-RIGHT SHUNTS(QLR). Pediatr Res 15 (Suppl 4), 464 (1981). https://doi.org/10.1203/00006450-198104001-00159
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DOI: https://doi.org/10.1203/00006450-198104001-00159