Effects of dextran infusion on cardiac output, oxygen delivery, and oxygen utilization in piglets during the first month of life
Meadow, W.L.; Rudinsky, B.F.
Critical Care Medicine 18(9): 980-984
1990
ISSN/ISBN: 0090-3493 PMID: 1697519 DOI: 10.1097/00003246-199009000-00015Document Number: 235365
We determined the effects of volume infusion on cardiac output, oxygen delivery (.ovrhdot.DO2), oxygen consumption (.ovrhdot.VO2), and oxygen extraction (O2 extr) in piglets at ages 5 to 14 days and 3 to 5 wk. Eighteen piglets were anesthetized, intubated, and mechanically ventilated. Six piglets (5 to 14 days old) and six piglets (3 to 5 wk old) received iv dextran (MW 70,000 daltons; 30 to 40 ml/kg) sufficient to raise mean left atrial pressure (LAP) from approximately 4 to 15 mm Hg over 30 min. Six piglets received 0.9% NaCl at 4 ml/kg .cntdot.h to maintain LAP constant of 4 mm Hg over a 30-min period. All piglets receiving dextran had increased cardiac output (mean elevation 39 .+-. 16 [SD]%; range + 19% to + 73%; p < .005). This response was mediated entirely by an elevation in stroke volume, as heart rate did not change significantly. However, all piglets receiving dextran reduced Hgb concentration (10.1 .+-. 1.5 to 7.5 .+-. 1.4 g/dl, p < .001), a decrease which completely offset the increase in cardiac output. Consequently, .ovrhdot.DO2 did not increase after dextran infusion (17.4 .+-. 1.8 to 18.4 .+-. 2.8 ml/min .cntdot. kg). Neither .ovrhdot.VO2 nor O2 extr changed significantly after dextran. No differences were noted in the response to dextran infusion comparing 5 to 14-day-old piglets with 3 to 5-wk-old piglets. Unlike fetal lambs, newborn piglets are able to elevate cardiac output significantly in response to volume loading. However, if these data can be extrapolated to human infants, volume infusion without concurrent blood transfusion is likely to increase systemic cardiac output but not improve .ovrhdot.DO2.