Cardiac output and ductal reopening during phototherapy in preterm infants.

Left ventricular output (LVO), left pulmonary artery blood flow (LPA) and patency of the ductus arteriosus (PDA) were studied with 2D/pulsed Doppler ultrasound before, during and after phototherapy treatment in 27 preterm infants (gestational age < or =32 wk), who were exposed for a minimum of 12 h to phototherapy for non-haemolytic hyperbilirubinemia. In 14 infants (52%) the ductus arteriosus reopened during phototherapy, but ductal patency was not of haemodynamic importance. LVO initially decreased in preterm infants in whom the ductus did not reopen.

Electrocortical brain activity during hypoxia and hypotension in anesthetized newborn lambs.

Blood gas and blood pressure disturbances do influence cerebral blood flow in newborns. To what extent cerebral blood flow changes affect electrocortical brain activity remains uncertain. We studied the effect of severe hypoxia and hemorrhagic hypotension on carotid artery blood flow and electrocortical brain activity in newborn anesthetized lambs.

Doppler sonographic study of the effect of indomethacin on cardiac and pulmonary hemodynamics of the preterm infant.

Objective: Indomethacin (INDO) causes an increase in systemic vascular resistance and decrease in perfusion of important organ systems in preterm infants treated for patent ductus arteriosus (PDA). Information on the effect of INDO on cardiac and pulmonary hemodynamics of these babies is scarce.

Methods: The left ventricular output (LVO), resistance in the ascending aorta (R(Ao)), determined mean cerebral blood velocity (cerebral-mv), ductal-peak and mean blood velocity (ductal-pv and -mv) and pulmonary artery peak and mean blood velocity (pulmonary pv and -mv) were measured, before, and up to 12 h after 0.

Near infrared spectroscopy-measured changes in cerebral blood volume and cytochrome aa3 in newborn lambs exposed to hypoxia and hypercapnia, and ischemia: a comparison with changes in brain perfusion and O2 metabolism.

Objectives: Validation of near infrared spectroscopy (NIRS)-measured changes in cerebral blood volume (deltaCBV) and cytochrome aa3 (deltaCytaa3) as estimators of changes in brain perfusion and oxygenation in the newborn lamb during hypoxia and hypercarbia, and additional hypotension.

Methods And Materials: In 33 newborn lambs brain perfusion assessed by carotid artery blood flow (deltaQcar: ml/min)and cerebral metabolic rate of oxygen (deltaCMRO2: ml O2/min) were related to NIRS-derived deltaCBV (ml/100 g) and deltaCytaa3 (microM) during combined hypoxia and hypercarbia and additional hypotension. Combined hypoxia and hypercapnia was induced by ventilation with 6-8% of O2 and 10% of CO2 during 30 min, and additional hypotension ( < 35 mmHg for 5 min) was induced by careful withdrawal of blood.

Haemodynamic consequences of phototherapy in term infants.

Unlabelled: The effect of blue-light phototherapy on cardiac output and brain and kidney perfusion was studied in 12 term infants with pulsed Doppler ultrasound. Mean (+/-SD) gestational age and birth weight were 39.0 (+/-1.

Pretreatment with allopurinol in cardiac hypoxic-ischemic reperfusion injury in newborn lambs exerts its beneficial effect through afterload reduction.

The aim of this study was to determine whether allopurinol (ALLO) reduces reperfusion injury inflicted upon the heart resulting from excess production of free oxygen radicals after hypoxia and ischemia (HI) in newborn animals. We, therefore, produced severe HI in 13 newborn lambs by low O2-ventilation and blood volume reduction. One hour before HI seven lambs received ALLO (20 mg/kg i.

Effect of deferoxamine on post-hypoxic-ischemic reperfusion injury of the newborn lamb heart.

Unlabelled: Post-hypoxic-ischemic (HI) reperfusion induces excess production of non-protein-bound iron (NPBI), leading to formation of the highly reactive hydroxyl radical. We investigated whether the iron-chelator deferoxamine (DFO) could reduce reperfusion injury and improve left ventricular (LV) function. We produced severe HI in 14 newborn lambs and measured pre-HI, upon reperfusion, 60 and 120 min after HI the following parameters: mean aortic blood pressure, total peripheral resistance, stroke volume (SV), ejection fraction (EF) and LV contractility (pre-HI, 60 and 120 min post-HI).

Effect of exchange transfusion on brain perfusion and electrocortical brain activity in newborn lambs.

Changes in brain perfusion (using ultrasonic-determined changes in carotid artery blood flow: Qcar) and electrocortical brain activity (ECBA, obtained by a Lectromed cerebral function monitor) were studied during exchange transfusion using the push-pull method in the newborn lamb. Changes in mean arterial blood pressure (MABP), Qcar, heart rate (HR), and ECBA were observed during all exchange transfusions: MABP, Qcar, and ECBA decreased during the withdrawal period and increased during the infusion period, whereas HR showed the opposite phenomenon. Changes in ECBA appeared to be primarily associated with changes in brain perfusion (p < 0.

The effect of phototherapy on cerebral blood flow velocity in preterm infants.

Cerebral blood flow velocity was studied with two-dimensional/pulsed Doppler ultrasound before, during and after discontinuation of phototherapy in 22 preterm infants (gestational age < or =32 weeks), who were treated for a minimum of 12h with blue-light phototherapy for non-haemolytic hyperbilirubinaemia. Before the cerebral blood flow velocity measurements, patency of the ductus arteriosus was diagnosed by Doppler echocardiography. All infants had normal brain ultrasound scans.

The effect of antioxidative combination therapy on post hypoxic-ischemic perfusion, metabolism, and electrical activity of the newborn brain.

Reoxygenation and reperfusion after severe hypoxia and ischemia (HI) contribute substantially to birth asphyxia-related brain injury. Excess production of free radicals via metabolization of arachidonic acid, xanthine oxidase, and non-protein-bound iron play an important role. Cerebral reperfusion injury is characterized by a decrease in perfusion, oxygen consumption, and electrical activity of the brain.

Effect of deferoxamine and allopurinol on non-protein-bound iron concentrations in plasma and cortical brain tissue of newborn lambs following hypoxia-ischemia.

Reduction of non-protein-bound iron (NPBI) using iron chelators may attenuate hypoxia-ischemia-induced reperfusion injury of the brain. This study investigated whether administration of low-dose deferoxamine and allopurinol, both having NPBI-chelating properties, reduced hypoxia-ischemia-induced NPBI formation in plasma effluent from the brain and in cerebral cortical tissue. Twenty-one newborn lambs underwent severe hypoxia-ischemia.

[Nitric oxide inhalation in newborn infants with pulmonary hypertension].

Nitric oxide (NO) is an important endogenous vasodilator. NO, produced in the endothelial cell, causes vasodilation by relaxation of the vascular smooth muscle cell. Inhalation of NO plays a role in the treatment of persistent pulmonary hypertension of the newborn, a syndrome with considerable morbidity and mortality.

The effect of phototherapy on renal blood flow velocity in preterm infants.

Mean renal blood flow velocity (RBFV) was studied with two-dimensional/ pulsed Doppler ultrasound and relative renal vascular resistance (RVR) was calculated before, during, and after phototherapy treatment in 30 preterm infants (gestational age < or = 32 weeks) who were treated for a minimum of 12 h with phototherapy for nonhemolytic hyperbilirubinemia. RBFV decreased, whereas RVR increased significantly after the initiation of phototherapy. In 'healthy' (nonventilated) infants RBFV and RVR returned to baseline values after discontinuation of phototherapy.

Effect of allopurinol on postasphyxial free radical formation, cerebral hemodynamics, and electrical brain activity.

Objective: Free radical-induced postasphyxial reperfusion injury has been recognized as an important cause of brain tissue damage. We investigated the effect of high-dose allopurinol (ALLO; 40 mg/kg), a xanthine-oxidase inhibitor and free radical scavenger, on free radical status in severely asphyxiated newborns and on postasphyxial cerebral perfusion and electrical brain activity.

Methods: Free radical status was assessed by serial plasma determination of nonprotein-bound iron (microM), antioxidative capacity, and malondialdehyde (MDA; microM).

Perinatal regulation of the cerebral circulation: role of nitric oxide and prostaglandins.

Nitric oxide (NO) influences cerebral vascular tone both in the normal fetus and in the hypoxemic fetus, but during postnatal life this regulating role of NO seems less prominent. It is therefore possible that under conditions when arterial oxygen content is at postnatal levels NO exerts no action on smooth muscle. We therefore examined the impact of NO on cerebral blood flow and vascular resistance in five near-term lamb fetuses during intrauterine ventilation and oxygenation.

Oxidative stress during post-hypoxic-ischemic reperfusion in the newborn lamb: the effect of nitric oxide synthesis inhibition.

Post-hypoxic-ischemic (HI) reperfusion induces endothelium and neurons to produce excessive amounts of nitric oxide and superoxide, leading to peroxynitrite formation, release of protein-bound metal ions (i.e. iron), and cytotoxic oxidants.

Nitric oxide inhibition after hypoxia-ischemia elevates pulmonary arterial pressure and increases oxygen need.

Inhibition of nitric oxide (NO) production may reduce post-hypoxic-ischemic (HI) neonatal brain damage, but may also induce pulmonary hypertension by inhibiting endogenous NO production in the pulmonary vascular bed. The aim of this study was to evaluate the effect of nitric oxide inhibition on pulmonary artery pressure and oxygen need after hypoxic ischemia. Severe HI was produced in 18 newborn lambs.

Effect of post-hypoxic-ischemic inhibition of nitric oxide synthesis on cerebral blood flow, metabolism and electrocortical brain activity in newborn lambs.

Since an excessive production of nitric oxide upon reperfusion/reoxygenation may play an important role in post-hypoxic-ischemic (HI) brain injury, we investigated whether immediate post-HI blockade of nitric oxide synthesis by N-omega-nitro-L-arginine (NLA) may reduce this injury. In 18 newborn lambs, subjected to severe HI, changes from pre-HI values were measured for carotid blood flow (Qcar [ml/min]) as a measure of changes in brain blood flow, (relative) cerebral metabolic rate of oxygen (CMRO2), and electrocortical brain activity (ECBA) at 15, 60, 120 and 180 min after HI. Upon completion of HI, at the onset of reperfusion and reoxygenation, 6 lambs received a placebo (control group), 6 low-dose NLA (10 mg/kg i.

Nonprotein-bound iron in postasphyxial reperfusion injury of the newborn.

Objective: To investigate if the availability of nonprotein-bound iron after birth asphyxia is related to the severity of the postasphyxial injury and neurodevelopmental outcome.

Methods: Nonprotein-bound iron (bleomycin assay) and thiobarbituric-acid-reactive species, an index of oxidative lipid damage, were measured in plasma of 50 newborn infants (gestational age > 34 weeks) between 0 to 8 hours, 8 to 16 hours, and 16 to 24 hours after birth. Three groups were compared: healthy infants (n = 20), moderately asphyxiated infants (n = 15), who were neurologically normal during the first 24 hours after birth and severely asphyxiated infants (n = 15), who developed abnormal neurological signs in the first 24 hours after birth.

Changes in cerebral hemodynamics and oxygenation during hypothermic cardiopulmonary bypass in neonates and infants.

Delay in development after open-heart surgery in infants has frequently been reported. Inadequate brain perfusion and oxygenation during deep hypothermic cardiopulmonary bypass (CPB) may play an important role. We investigated the effect of CPB on cerebral perfusion and oxygenation in 12 neonates and infants (age 0-11 months) undergoing open-heart surgery.

Inhalation of nitric oxide: effect on cerebral hemodynamics and activity, and antioxidant status in the newborn lamb.

Ventilation with nitric oxide (NO) is increasingly being used to treat pulmonary hypertension in the newborn. In the brain, NO has vasoactive properties and is involved in neurotransmission. However, the effect of inhaled NO on the cerebral blood flow (CBF) and on the cerebral activity is not known.

Respiratory illness in families of preterm infants with chronic lung disease.

AIMS--To examine the relation, based on two types of questionnaires, between (1) chronic lung disease of the newborn (CLDN) and lower respiratory illness (LRI) in siblings, and between (2) CLDN and asthma, chronic obstruction pulmonary disease (COPD), or allergy in parents and grandparents. METHODS--Data from 209 children born before 32 weeks of gestation were randomly taken from the records of three neonatal units. Taking into account age and gender, the excess of LRI was calculated for each family compared with the average of all families.

Biochemical lung maturity, static respiratory compliance, and pulmonary gas transfer in intubated preterm infants with and without respiratory distress syndrome.

We investigated the relationship between tests of biochemical lung maturity [lecithin/sphingomyelin ratio (L/S ratio)], static compliance of the respiratory system (Crs), and estimates of pulmonary gas transfer [venous admixture and arterial/alveolar (a/A) ratio] in a group of intubated preterm infants with and without respiratory distress syndrome (RDS). Thirty infants were studied once (n = 26) or twice (n = 4). The L/S ratio was obtained by means of high-performance thin-layer chromatography and determination of the phosphorus content.

Effect of indomethacin on cerebral blood flow and oxygenation in the normal and ventilated fetal lamb.

Indomethacin lowers fetal and neonatal brain blood flow and may reduce the risk of periventricular-intraventricular hemorrhage. However, concerns have been raised that cerebral O2 metabolism may be compromised at lower cerebral perfusion pressures. In 17 near-term lamb fetuses, changes in brain blood flow and cerebral O2 metabolism (CMRO2) were measured at mean carotid arterial pressures (MCBP) ranging from 8 to 70 mm Hg.

Interaction between afterload and contractility in the newborn heart: evidence of homeometric autoregulation in the intact circulation.

Objectives: We undertook the present study to determine whether afterload and contractility interact in the hearts of newborn lambs. We specifically investigated whether stepwise increases in afterload increase contractility.

Background: Several studies in the isolated and intact adult dog heart have shown that afterload and contractility are not independent determinants of cardiac performance; rather, they interact.