Volume infusions are commonly administered in the NICU, presumably to improve hemodynamic performance. We wondered whether recent improvements in non-invasive assessments of hemodynamic function in newborn infants would allow us test the validity of this presumption.

Methods: We assessed the hemodynamic consequences of two common`volume' infusions in the NICU; 1) packed red blood cells (PRBC; 15 mL/kg over 2-3 hours; n=12 infants), and 2) fresh frozen plasma(FFP; 15 mL/kg over 1 hour; n=7 infants). Before and after each infusion, we measured hematocrit (Hct) and aortic root cross section area (one measurement each), and aortic root blood velocity time integral (VTI), heart rate (HR), arterial oxygen saturation (SatO2) (ten measurements each over a 5-minute interval). From these observations, we calculated cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and oxygen delivery (QO2).

Results: 1) Variations in measurement of VTI (and consequently CO) were surprisingly narrow. For 380 determinations (19 infants; 10 measurements/interval; pre- and post-tx), the `band-width' of VTI measurements(average of standard deviation/mean value) was 4.2% (range 1.7 to 7.4%). 2) As anticipated, PRBC infusion significantly elevated Hct (29± 16% [s.d.]; p<0.001). However, PRBC infusion had no significant impact on CO, HR, or SV. Consequently, the rise in QO2 after PRBC (23 ± 18%; p<0.01) was entirely accounted for by the rise in Hct. In addition, PRBC infusion elevated both BP and SVR (17 ± 22%; 25 ± 32%; both p<0.02). 3) In contrast to PRBC, FFP infusion had no significant impact on any hemodynamic variable (ΔCO= 8.0 ± 18%; ΔHR= -2± 7%; both p=n.s.), though BP tended to rise (18 ± 22%) and Hct tended to fall (-12 ± 16%) after FFP (both p = 0.15).

Conclusions: 1) Cardiac performance (including CO) can be reliably determined non-invasively in the NICU; within 5-minute intervals, the band-width of measurements of CO was less than 5%. 2) Despite common lore, neither PRBC nor FFP infusion significantly increased CO in neonates. 3) PRBC infusion elevated QO2 by increasing Hct, and raised BP and SVR by an as yet undetermined mechanism. 4) Volume infusions in the NICU may have legitimate rationales, but improving CO isn't among them.