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Cerebral haemodynamics in preterm infants after exposure to dexamethasone
A Pellicer1, F Gayá, T A Stiris
1Division of Neonatology, La Paz Children's Hospital, Madrid, Spain.
Insights
Dexamethasone alters brain hemodynamics in preterm infants, increasing cerebral blood flow and affecting cerebral blood volume. These changes are linked to cumulative effects and direct vascular actions of the drug.
Area of Science:
- Neonatal Physiology
- Pharmacodynamics
- Cerebrovascular Regulation
Background:
- Preterm infants often require respiratory support and may develop chronic lung disease.
- Dexamethasone is used to manage certain conditions in preterm infants, but its effects on brain hemodynamics are not fully understood.
Purpose of the Study:
- To determine the impact of dexamethasone on brain hemodynamics in ventilated preterm infants.
- To explore the pathophysiological mechanisms underlying dexamethasone's effects on cerebral circulation.
Main Methods:
- Prospective study of 12 ventilated preterm infants receiving dexamethasone.
- Near-infrared spectroscopy used to measure cerebral blood flow (CBF) and cerebral blood volume (CBV).
- Measurements taken before and at multiple time points after dexamethasone doses, with continuous monitoring of vital signs.
Main Results:
- Significant short-term changes in cerebral blood volume were observed after dexamethasone administration.
- Mean cerebral blood flow increased progressively with repeated dexamethasone doses.
- Blood pressure was higher with later doses, but no direct correlation with CBF changes was found; transcutaneous PCO2 decreased.
Conclusions:
- Postnatal dexamethasone significantly alters cerebral hemodynamics in preterm infants.
- Observed changes are likely due to a combination of direct vascular effects and the cumulative impact of the drug.
Aim:
To determine changes in brain haemodynamics produced by dexamethasone; to evaluate the pathophysiological conditions involved in the effect of dexamethasone.
Methods:
A prospective study was made of 12 ventilated preterm infants who received dexamethasone (0.25 mg/kg/12 hours) for ongoing chronic lung disease or extubation failure. Cerebral blood flow (CBF), absolute cerebral blood volume (CBV), and cerebral blood volume changes (delta CBV) were estimated by near infrared spectroscopy, before and 10, 30, 60, 120, 180 and 240 minutes after the first, third, and fifth doses of dexamethasone. All patients were monitored continuously using pulse oximetry, transcutaneous blood gases, and blood pressure.
Results:
There were significant short term changes in delta CBV on each day of the study; delta CBV increased significantly at 240 minutes compared with values before the first dose, and from 120 minutes onward during the third and fifth doses. However, mean CBV values averaged over 240 minutes after the first, third, and fifth doses did not vary. Mean CBF values averaged over 240 minutes increased progressively up to the fifth dose (significant differences between the first and fifth dose). The short term changes in CBF consisted of a significant increase 60 minutes after dexamethasone administration compared with the before and 10 minute values in every study. Blood pressure was significantly higher in the third and fifth doses than in the first dose. Blood pressure showed no short term changes. There was no correlation between CBF and blood pressure changes. TcPCO2 (transcutaneous PCO2) decreased significantly throughout the study period, with the average mean value in the fifth dose significantly lower than in the first dose. Nevertheless, no short term changes in TcPCO2 were observed.
Conclusions:
Postnatal systemic dexamethasone administration produced significant changes in cerebral haemodynamics that seemed to be related to both a direct effect on regional vessel walls and the cumulative effect of dexamethasone.