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Updated: Jul 12, 2026
A Piglet Model of Neonatal Hypoxic-Ischemic Encephalopathy
Published on: May 16, 2015
Intrauterine growth restriction improves cerebral O2 utilization during hypercapnic hypoxia in newborn piglets
Reinhard Bauer1, Bernd Walter, Ulrich Brandl
1Institute of Molecular Cell Biology, Center for Molecular Biomedicine, and Department of Neuropaediatrics, Children's Hospital, Friedrich Schiller University, D-07740 Jena, Germany. reinhard.bauer@mti.uni-jena.de
Insights
Intrauterine growth-restricted (IUGR) newborns show improved brain oxygen supply during asphyxia. This enhanced cerebral oxygen utilization helps IUGR piglets better meet brain oxygen demands compared to normal weight neonates.
Area of Science:
- Neonatal physiology
- Perinatal medicine
- Cerebrovascular regulation
Background:
- Cerebrovascular regulation during asphyxia is crucial for preventing brain oxygen deficit in newborns.
- Data on intrauterine growth restriction (IUGR) effects on neonatal brain oxygen supply during asphyxia are limited.
Purpose of the Study:
- To investigate the hypothesis that IUGR enhances neonatal cerebrovascular regulation during asphyxia.
- To examine the impact of IUGR on cerebral blood flow (CBF) and oxygen consumption (CMRO2) under varying hypoxic and hypercapnic conditions.
Main Methods:
- Utilized 1-day-old anesthetized and ventilated piglets, divided into normal weight (NW) and IUGR groups.
- Induced moderate and severe hypoxia (normocapnic) and hypoxia/hypercapnia (asphyxia) for 1 hour.
- Measured cerebral blood flow, cerebral metabolic rate for oxygen, and hemoglobin-oxygen affinity.
Main Results:
- IUGR piglets exhibited markedly increased cerebral oxygen extraction during asphyxia.
- A diminished increase in CBF relative to CMRO2 was observed in IUGR piglets as arterial oxygen content decreased.
- Enhanced cerebral oxygen utilization was evident in IUGR piglets under graded asphyxia, improving oxygen availability.
Conclusions:
- IUGR newborns demonstrate a greater capacity to ensure brain oxygen demand during asphyxia (hypercapnic hypoxia) compared to normal weight neonates.
- Improved cerebral oxygen utilization, not hemoglobin-oxygen affinity, underlies the enhanced brain oxygen supply in IUGR piglets during asphyxia.
Abstract:
Data are scant regarding the capacity of cerebrovascular regulation during asphyxia for prevention of brain oxygen deficit in intrauterine growth-restricted (IUGR) newborns. We tested the hypothesis that IUGR improves the ability of neonates to withstand critical periods of severe asphyxia by optimizing brain oxygen supply. Studies were conducted to examine the effects of IUGR on cerebral blood flow (CBF) regulation and oxygen consumption (cerebral metabolic rate for oxygen, CMRO(2)) at different stages of asphyxia (hypercapnic hypoxaemia) in comparison to pure hypoxia (normocapnic hypoxaemia). We used 1-day-old anaesthetized and ventilated piglets. Animals were divided into normal weight (NW) piglets (n = 47; aged 11-26 h, body weight 1481 +/- 121 g) and IUGR piglets (n = 48; aged 13-28 h, body weight 806 +/- 42 g) according to their birth weight. Different stages of hypoxaemia were induced for 1 h by appropriate lowering of the inspired fraction of oxygen (moderate hypoxia: = 31-34 mmHg; severe hypoxia: = 20-22 mmHg). Fourteen NW and 16 IUGR piglets received additionally 9% CO(2) in the breathing gas, so that a of 74-80 mmHg resulted (hypoxia/hypercapnia groups). Eight NW and nine IUGR animals served as untreated controls. Furthermore, affinity of haemoglobin for oxygen was measured under hypoxic and asphyxic conditions. During asphyxia cerebral oxygen extraction was markedly increased in IUGR animals (P < 0.05). This resulted in a significantly diminished CMRO(2)-related increase of CBF at gradually reduced arterial oxygen content (P < 0.05). Therefore, an enhanced effectivity in oxygen availability appeared in newborn IUGR piglets under graded asphyxia by improved cerebral oxygen utilization (P < 0.05). This was not supported by related O(2) affinity of haemoglobin. Thus, IUGR newborns are more capable to ensure brain O(2) demand during asphyxia (hypercapnic hypoxia) than NW neonates.
