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Circulatory and metabolic effects of anemia in hyperinsulinemic ovine fetuses
A Papparella1, D Berard, B S Stonestreet
1Department of Pediatrics, Brown University School of Medicine, Women and Infants' Hospital of Rhode Island, Providence 02905.
Insights
Fetal hyperinsulinemia from maternal diabetes can lead to anemia. In this study, anemic, hyperinsulinemic fetuses compensated for reduced oxygen delivery by increasing blood flow to vital organs.
Area of Science:
- Perinatal medicine
- Fetal physiology
- Endocrinology
Background:
- Maternal diabetes mellitus increases risks for fetal complications like perinatal asphyxia and cardiovascular issues.
- Hyperinsulinemic fetuses may develop anemia due to pregnancy or delivery complications, impacting oxygen transport.
- Experimental fetal hyperinsulinemia causes cardiovascular changes and elevated catecholamines.
Purpose of the Study:
- To investigate if anemic hypoxia compromises the compensated hyperinsulinemic fetus.
- To determine how reduced fetal oxygen availability affects cardiovascular and metabolic responses in hyperinsulinemic fetuses.
Main Methods:
- Chronically catheterized ovine fetuses received insulin or placebo for 48 hours.
- Anemia was induced via isovolemic exchange transfusion.
- Regional blood flow, oxygen delivery, extraction, and uptake were measured.
Main Results:
- Anemic hypoxia augmented insulin-mediated norepinephrine surge and increased blood flow to brain, heart, and adrenal glands.
- Combined ventricular output was sustained during anemia.
- Systemic oxygen uptake was preserved, but regional oxygen delivery decreased to various tissues.
Conclusions:
- The hyperinsulinemic fetus can compensate for anemic hypoxia.
- Compensation occurs through increased or sustained regional vascular perfusion.
- These findings highlight fetal adaptive mechanisms to compromised oxygen availability in diabetic pregnancies.
Abstract:
Infants born to women with poorly controlled diabetes mellitus have an increased incidence of perinatal asphyxia, cardiovascular abnormalities, elevated catecholamines, and sudden fetal death. Although hyperinsulinemic fetuses of diabetic women often exhibit polycythemia, they may also develop anemia because of pregnancy- and/or delivery-related complications. Experimental fetal hyperinsulinemia results in cardiovascular changes and a surge in catecholamines. We hypothesized that reductions in fetal O2 availability via anemic hypoxia limits O2 transport and compromises the hemodynamically and metabolically stressed but compensated hyperinsulinemic fetus. Chronically catheterized fetuses receiving insulin (n = 9) or placebo (n = 5) for 48 h were rendered anemic by an isovolemic exchange transfusion. In the hyperinsulinemic state, anemic-hypoxia augmented the insulin-mediated surge in norepinephrine concentration and increases in blood flow to brain, heart, and adrenal glands. Insulin-related increase in the combined ventricular output was sustained during anemia. O2 delivery to the fetus decreased, extraction increased, and O2 uptake did not change. Regional O2 delivery to the brain, kidney, gastrointestinal tract, muscle, fat, pancreas, spleen, and carcass decreased. Hyperinsulinemic ovine fetus exposed to anemic hypoxia demonstrated an accentuated surge in norepinephrine, a sustained increase in the combined ventricular output, preservation of systemic O2 uptake, and compromised regional O2 delivery to certain vascular regions. We conclude that the hyperinsulinemic fetus was able to compensate for anemic hypoxia by increased or sustained regional vascular perfusion.
