Cerebral blood flow during treatment for pulmonary hypertension

A randomized, double-blind, placebo-controlled, prospective study of bosentan for the treatment of persistent pulmonary hypertension of the newborn

OBJECTIVE

To assess the efficacy and safety of bosentan as an adjuvant therapy of persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Forty-seven neonates with PPHN were randomly assigned to receive either bosentan (n=24) or placebo (n=23). Efficacy was evaluated with a favorable outcome defined as fulfilling all the following criteria (for example, oxygenation index <15, normal pulmonary artery pressure (<20 mm Hg) and no premature discontinuation of the drug because of drug-related toxicity or lack of efficacy). Evaluation of safety was done by monitoring drug-related adverse events.

RESULT

Bosentan treatment was superior to placebo with a favorable response in 87.5% of patients treated with bosentan as compared with 20% of those who received placebo (P<0.0001). None of patients in the bosentan group had drug-related clinical or laboratory adverse events.

CONCLUSION

Bosentan may be a useful adjuvant therapy of PPHN.

Nitric oxide: considerations for the treatment of ischemic stroke

Some 40 years ago it was recognized by Furchgott and colleagues that the endothelium releases a vasodilator, endothelium-derived relaxing factor (EDRF). Later on, several groups identified EDRF to be a gas, nitric oxide (NO). Since then, NO was identified as one of the most versatile and unique molecules in animal and human biology. Nitric oxide mediates a plethora of physiological functions, for example, maintenance of vascular tone and inflammation. Apart from these physiological functions, NO is also involved in the pathophysiology of various disorders, specifically those in which regulation of blood flow and inflammation has a key role. The aim of the current review is to summarize the role of NO in cerebral ischemia, the most common cause of stroke.

High prevalence of minor neurologic deficits in a long-term neurodevelopmental follow-up of children with severe persistent pulmonary hypertension of the newborn: a cohort study

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is a severe condition that determines a profound brain hypoxia. Inhaled nitric oxide was approved for the treatment of PPHN since the end of the 1990s. The debate upon the long term outcome of these children is still open. Our aim was to investigate the incidence of minor long-term neurodevelopmental problems in a cohort of children affected by severe PPHN.

METHODS

All neonates with severe PPHN treated with inhaled nitric oxide in our facility between 01.01.02 and 31.12.07 were seen in a follow up visit and evaluated with a neurodevelopmental scale, according to their age at the time of observation.

RESULTS

in the study period 31 children were diagnosed with severe PPHN. 29 survived. 27 accepted to come for follow-up. Mean age: 41 months (range 12 - 70 months).26% of the evaluated children had some behavioural problems, while 22% had some language disturbances.

CONCLUSIONS

This is the first neurodevelopmental follow-up of neonates with PPHN in which children older than 36 months have been evaluated.There is an unexpected high incidence of minor neurological deficits, mainly regarding the fields of language and behaviour. These deficits seem to be related to the severity of illness rather than to the treatment. Language and behaviour are considered "higher functions" in humans and their integrity can be better defined in older children.

Developmental outcomes in persistent pulmonary hypertension treated with nitric oxide therapy

BACKGROUND

The aim of the present study was to assess 3 year auditory and neurodevelopmental outcomes of persistent pulmonary hypertension of the newborn (PPHN) before and after introducing inhaled nitric oxide (i-NO) therapy, and to detect the clinical factors affecting poor outcome.

METHODS

A retrospective historical cohort study of 26 survivors with PPHN with oxygenation index (OI) >or=25 (13 infants without i-NO therapy, control group; 13 with i-NO therapy, i-NO group) was performed. Auditory brainstem response (ABR) at 6 and 12 months and neurodevelopmental outcomes at 3 years of age were evaluated.

RESULTS

ABR abnormalities at 6 months were observed in one infant in the i-NO group and six in the control group (P = 0.04). At 1 year, one infant in the i-NO group and two of six infants in the control group still had ABR abnormality. In the i-NO group, two children had abnormal neurodevelopmental outcomes, as compared with five children in the control group at 3 year follow up. Two children in the control group and no children in the i-NO group had hearing loss at 3 years of age. Hypocapnea (P = 0.04) and elevated creatine phosphokinase (P = 0.04) were found to be most predictive for neurodevelopmental abnormality.

CONCLUSION

Avoidance of excessive hypocapnea via introduction of i-NO therapy might reduce both ABR and neurodevelopmental abnormalities.

Biopterin in the acute phase of hypoxia-ischemia in a neonatal pig model

To clarify the participation of inducible NOS (iNOS) in the hypoxia-ischemia, we examined iNOS and its tetrahydrobiopterin co-factor in the cerebral cortex and plasma in a newborn-piglet model. We also investigated the role of hypothermia in iNOS expression and biopterin production. Male newborn piglets were ventilated 6% oxygen for 45 min. Their common carotid arteries were clamped during hypoxia. Then they were resuscitated with 30% oxygen (HI group). Piglets of the hypothermia group were treated as the HI group and their body was cooled to 35.5 degrees C after hypoxic-ischemic insults. Sham-treated piglets were also reserved. In the HI group, iNOS was present in neurons and macrophages of the cerebral cortex 12h after the insult. The concentrations of nitrite and nitrate were elevated in the cerebral cortex 12h after hypoxic-ischemic insults but the biopterin level was unchanged. The plasma biopterin concentration after the insult (377.9+/-78.7 nM) was five times higher than before the insult (80.1+/-4.3 nM); this level peaked 4h after the insult (604.8+/-200.9 nM) and only slightly decreased after 12h (445.9+/-57.8 nM). In the hypothermia group, no iNOS expression was observed 12h after the insult. The plasma biopterin concentration after the insult (464.2+/-92.3 nM) was similar to that in the HI group, but was suppressed by 4h of hypothermia (229.3+/-106.8 nM). In this study, neuronal iNOS expression and increase of NO production were found in the acute phase of hypoxia-ischemia. Brain biopterin did not increase in hypoxia-ischemia although plasma biopterin was five-fold elevated. The discrepancy may also affect hypoxic-ischemic organ damage.

Inhaled nitric oxide treatment inhibits neuronal injury after meconium aspiration in piglets

BACKGROUND

Meconium aspiration-induced hypertensive lung injury is frequently associated with neuronal damage. Inhaled nitric oxide (iNO) is widely used in the treatment of pulmonary hypertension, but its effects on the brain are poorly known.

AIMS

The aim of this study was to determine the effects of iNO treatment on the neuronal tissue after meconium aspiration.

STUDY DESIGN

71 anesthetized, catheterized and ventilated newborn piglets were studied for 6 h. Thirty-five piglets were instilled with a bolus of human meconium intratracheally and 36 piglets with saline instillation served as controls. Nineteen meconium piglets and 17 control piglets were continuously treated with 20 ppm of iNO, started at 30 min after the insult. The extent of neuronal injury was analysed histologically, and the levels of brain tissue lipid peroxidation products, reduced glutathione (GSH), myeloperoxidase activity and oxidized DNA were analysed as indicators of oxidative stress.

RESULTS

iNO treatment diminished the pulmonary hypertensive response caused by meconium aspiration, but did not change systemic or carotid hemodynamics. NO administration was associated with reduced neuronal injury and diminished amount of oxidized DNA in the hippocampus of the meconium piglets. Further, iNO treatment was associated with decreased level of GSH in the cortex, but no change in lipid peroxidation production or myeloperoxidase activity was detected in any of the studied brain areas.

CONCLUSIONS

Our results suggest that iNO treatment may inhibit DNA oxidation and neuronal injury in the hippocampus, associated with newborn meconium aspiration.

Persistent pulmonary hypertension of the newborn: pathogenesis, etiology, and management

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by severe hypoxemia shortly after birth, absence of cyanotic congenital heart disease, marked pulmonary hypertension, and vasoreactivity with extrapulmonary right-to-left shunting of blood across the ductus arteriosus and/or foramen ovale. In utero, a number of factors determine the normally high vascular resistance in the fetal pulmonary circulation, which results in a higher pulmonary compared with systemic vascular pressure. However, abnormal conditions may arise antenatally, during, or soon after birth resulting in the failure of the pulmonary vascular resistance to normally decrease as the circulation evolves from a fetal to a postnatal state. This results in cyanosis due to right-to-left shunting of blood across normally existing cardiovascular channels (foramen ovale or ductus arteriosus) secondary to high pulmonary versus systemic pressure. The diagnosis is made by characteristic lability in oxygenation of the infant, echocardiographic evidence of increased pulmonary pressure, with demonstrable shunts across the ductus arteriosus or foramen ovale, and the absence of cyanotic heart disease lesions. Management of the disease includes treatment of underlying causes, sedation and analgesia, maintenance of adequate systemic blood pressure, and ventilator and pharmacologic measures to increase pulmonary vasodilatation, decrease pulmonary vascular resistance, increase blood and tissue oxygenation, and normalize blood pH. Inhaled nitric oxide has been one of the latest measures to successfully treat PPHN and significantly reduce the need for extracorporeal membrane oxygenation.

Inhaled nitric oxide therapy might reduce the need for hyperventilation therapy in infants with persistent pulmonary hypertension of the newborn

AIM

To determine whether inhaled nitric oxide might reduce the need for excessive respiratory alkalosis to maintain systemic oxygenation in infants with persistent pulmonary hypertension of the newborn (PPHN).

MATERIALS AND METHODS

A retrospective historical cohort study of 34 infants with PPHN with oxygenation index (OI) of 25 or more, including 19 infants without inhaled nitric oxide (i-NO) therapy (control group) and 15 infants with inhaled nitric oxide therapy (i-NO group) was performed. The initial dose of 10 ppm of i-NO was administered and no responders received the maximum dose of 25 ppm. We evaluated the mortality rate and the change of OI index and PaCO(2) during the first 6 days.

RESULTS

There were no significant differences in characteristics between groups. Two of 15 in the i-NO group and 6 of 19 infants in the control group died during the first 48 h. Baseline OI, PaCO(2) and arterial pH were similar in the two groups. OI in the i-NO group was significantly higher than in the control group between 12 and 96 h. PaCO(2) in the i-NO group was higher than in the control group between 24 and 144 h.

CONCLUSION

i-NO therapy for PPHN might improve systemic oxygenation without excessive hypocapnia. However there was no reduction in duration of ventilation support or oxygen supply.

Contribution of pulmonary surfactant with inhaled nitric oxide for treatment of pulmonary hypertension

BACKGROUND

Combined therapy of inhaled nitric oxide (iNO) with pulmonary surfactant replacement was reported to improve oxygenation in patients or animal models of persistent pulmonary hypertension of the newborn with pulmonary surfactant deficiency lung. To evaluate the potential of iNO for the treatment of persistent pulmonary hypertension of the newborn, pulmonary arterial pressure (PAP) was measured during iNO before and after pulmonary surfactant replacement in an animal model of pulmonary hypertension with surfactant deficiency.

METHODS

Seven newborn piglets were injected with L-nitro-arginine-methylester to produce an animal model of pulmonary hypertension. After PAP increased, iNO (30 p.p.m.) was introduced. Then iNO was stopped, and animals were subjected to lung lavage with saline. After recording the effect of iNO, all animals then received exogenous pulmonary surfactant installation. After surfactant treatment, iNO was again introduced.

RESULTS

Pulmonary arterial pressure and systemic arterial pressure were increased significantly by >30% after infusion of L-nitro-arginine-methylester. During iNO only PAP was reduced significantly. Respiratory system compliance decreased significantly after lung lavage, and increased significantly after pulmonary surfactant replacement with concomitant increase of PaO2. In contrast, significant reduction of PAP with iNO before and after pulmonary surfactant replacement were also observed. The reduction ratios of PAP under each condition were 75.2 +/- 7.4%, 81.3 +/- 3.1%, and 79.1 +/- 5.3%, respectively (not significant among conditions).

CONCLUSION

These results suggest that iNO is still a potent pulmonary arterial vasodilator even under pulmonary surfactant deficiency in an animal model of pulmonary hypertension.

Meconium aspiration induces neuronal injury in piglets

AIM

Meconium aspiration-induced hypertensive lung injury, especially when connected with perinatal asphyxia, has been associated with brain damage. We aimed to determine the neuronal injury induced by pulmonary meconium contamination alone and with concurrent asphyxia.

METHODS

36 anaesthetized and ventilated newborn piglets were haemodynamically monitored for 6 h. Seven piglets without concurrent asphyxia and seven piglets with asphyxia were instilled with a bolus of human meconium intratracheally. Seven piglets had only asphyxia and 15 piglets served as controls. The brains were studied histologically.

RESULTS

Meconium aspiration did not change systemic haemodynamics acutely, while its combination with asphyxia diminished the abrupt postasphyxic systemic hypertensive peak and resulted in a transient increase in carotid artery flow, not seen after isolated asphyxia. Systemic pressure declined after 4 h in all insulted groups, but only isolated asphyxia was associated with a sustained decrease in carotid artery flow. Arterial oxygenation remained normal, except during the acute insults. Brain examination after meconium instillation indicated neuronal injury, especially in the CA3 region of the hippocampus. Asphyxia resulted in neuronal injury in the cortical, cerebellar and hippocampal hilus regions.

CONCLUSION

Severe meconium aspiration itself may result in hippocampal neuronal injury.

Three-year follow up of term and near-term infants treated with inhaled nitric oxide

BACKGROUND

The present study describes the outcome at 3 years in term and near-term infants treated with inhaled nitric oxide (iNO) for persistent pulmonary hypertension of the newborn (PPHN).

METHODS

The study population consisted of 18 infants delivered at 34 weeks by best obstetric estimate who were admitted to the neonatal intensive care units with a diagnosis of PPHN.

RESULTS

Eighteen infants (mean gestational age 38.5 +/- 2.6 weeks, mean birthweight 3015 +/- 587 g) were treated with iNO. The mean oxygenation index before iNO was 27.2 +/- 15.2. Responses to iNO were classified into three groups: (i) early response in eight infants; (ii) late response in two; and (iii) poor response in eight infants. Three infants died within seven postnatal days. Fifteen surviving infants were followed up to 3 years. The mean developmental scale was 98.4 +/- 9.0. One infant was diagnosed with severe neurodevelopmental disability due to cerebral palsy. Another infant was diagnosed with mild neurodevelopmental disability because of a low developmental scale. No infant showed significant hearing loss. Five infants had reactive airway disease (RAD) at 18 months, these infants required a significantly longer duration of mechanical ventilation in their neonatal period than non-RAD infants (P = 0.02). The frequency of survival with normal neurodevelopmental outcome was significantly higher in the early response group than the late or poor response groups (P = 0.03).

CONCLUSION

In iNO-treated PPHN, mortality and neurodevelopmental outcome were associated with response to iNO, and pulmonary outcome was associated with duration of mechanical ventilation.

Asphyxia aggravates systemic hypotension but not pulmonary hypertension in piglets with meconium aspiration

Meconium aspiration and birth asphyxia are both separately connected to significant pulmonary and systemic hemodynamic changes in newborns, but, although these insults frequently coexist, their combined effects on the neonatal circulation are still controversial. To determine the pulmonary and systemic circulatory changes induced by pulmonary meconium contamination with concurrent asphyxia, 41 anesthetized and ventilated newborn piglets (10-12 d) were studied for 6 h. Eleven piglets were instilled with a bolus of human meconium intratracheally, and 10 piglets had meconium instillation with immediate induction of an asphyxic insult. Eight piglets had only asphyxia and 12 ventilated piglets served as controls. Meconium instillation (with and without asphyxia) resulted in a sustained decrease in the oxygenation, which remained, however, on the control level in the asphyxic group. Although meconium insufflation (with and without asphyxia) increased pulmonary artery pressure and vascular resistance progressively during the study period, the meconium-induced hypertensive effect was actually diminished by additional asphyxia. Asphyxia alone did not have any effect on these pulmonary hemodynamic parameters. On the other hand, whereas systemic arterial pressure and vascular resistance remained on the control level after meconium instillation alone, asphyxia (with and without pulmonary meconium insult) resulted in a sustained fall in systemic pressure already by 4 h. Our data thus indicate that although the coexisting asphyxia seems to moderate the meconium aspiration-induced pulmonary hypertensive response, this additional asphyxic insult does not affect the associated hypoxemia, but rather significantly exacerbates systemic hypotension.

The influence of inhaled nitric oxide on cerebral blood flow and metabolism in a child with traumatic brain injury

IMPLICATIONS

The effects of inhaled nitric oxide (INO) on cerebrovascular hemodynamics are not well established. We report no adverse cerebral effects with INO therapy in a child with traumatic brain injury.