Treatment Of Neonatal Pulmonary Hypertension Research Articles

Efficacy and safety of a novel nitric oxide generator for the treatment of neonatal pulmonary hypertension: Experimental and clinical studies

Persistent pulmonary hypertension of the newborn (PPHN) is a complex pathology resulting from a failure of the post-natal reduction in pulmonary vascular resistance leading to hypoxemia. The standard therapy is inhaled Nitric Oxide (NO) improving oxygenation but its availability is limited, especially in hospitals with restricted financial resources. We evaluated the efficacy and safety of a new device generating NO (TAS + PLUS), in three experimental piglet models of pulmonary hypertension (PH), and we later tested its application in a pilot study of newborn patients suffering from PPHN.Piglets with experimentally induced PH showed a decrease in pulmonary arterial pressure (PAP) after breathing NO. Both acute and chronic exposure of piglets and rats did not cause any adverse effect in blood gas levels and biological parameters. A pilot study including 32 patients suffering from PPHN showed an increase in oxygen saturation (SatO2) and partial pressure of oxygen in arterial blood (PaO2) leading to a decrease of Oxygenation Index (OI) after compassionate treatment with NO from TAS + PLUS device.The device showed effectiveness and safety both in experimental PH and in the clinical setting. Therefore, it represents an excellent alternative for PPHN management in conditions where commercial NO is unavailable.

2-Aminoethyldiphenylborinate modifies the pulmonary circulation in pulmonary hypertensive newborn lambs partially gestated at high altitude

Calcium signaling through store operated channels (SOC) is involved in hypoxic pulmonary hypertension. We determined whether a treatment with 2-aminoethyldiphenylborinate (2-APB), a compound with SOC blocker activity, reduces pulmonary hypertension and vascular remodeling. Twelve newborn lambs exposed to perinatal chronic hypoxia were studied, 6 of them received a 2-APB treatment and the other 6 received vehicle treatment, for 10 days in both cases. Throughout this period, we recorded cardiopulmonary variables and on day 11 we evaluated the response to an acute hypoxic challenge. Additionally, we assessed the vasoconstrictor and vasodilator function in isolated pulmonary arteries as well as their remodeling in lung slices. 2-APB reduced pulmonary arterial pressure at the third and tenth days, cardiac output between the fourth and eighth days, and pulmonary vascular resistance at the tenth day of treatment. The pulmonary vasoconstrictor response to acute hypoxia was reduced by the end of treatment. 2-APB also decreased maximal vasoconstrictor response to the thromboxane mimetic U46619 and endothelin-1 and increased maximal relaxation to 8-Br-cGMP. The maximal relaxation and potency to phosphodiesterase-5 and Rho-kinase inhibition with sildenafil and fasudil respectively, were also increased. Finally, 2-APB reduced the medial and adventitial layers' thickness, the expression of α-actin and the percentage of Ki67+ nuclei of small pulmonary arteries. Taken together, our results indicate that 2-APB reduces pulmonary hypertension, vasoconstrictor responses and pathological remodeling in pulmonary hypertensive lambs. We conclude that SOC targeting may be a useful strategy for the treatment of neonatal pulmonary hypertension, however, further testing of specific blockers is needed.

The Use of Sildenafil in Persistent Pulmonary Hypertension of the Newborn

We evaluated the effectiveness of sildenafil in the treatment of neonatal pulmonary hypertension. We performed a double-blind randomized clinical trial in 51 full-term infants with persistent pulmonary hypertension confirmed by Doppler echocardiography. Patients were divided in two groups: 20 infants in group A received placebo when the oxygenation index was >20, and 31 infants in group B received 3 mg/kg of oral sildenafil every 6 hours. Arterial blood gases were taken at 1, 4, 7, 13, 19, and 25 hours after treatment was started. Main outcome measures were oxygenation changes, time on mechanical ventilation, and mortality. Both groups were comparable in general variables as well as in illness severity. We observed better oxygenation parameters after 7 hours of sildenafil treatment, but no significant changes were found in the placebo group. Mortality was higher in the placebo group (40%) than in those infants who received sildenafil (6%; P = 0.004), although no difference was found in time on mechanical ventilation between groups. Our results confirm that sildenafil may be a useful adjuvant therapy for term infants with pulmonary hypertension in centers lacking inhaled nitric oxide and extracorporeal membrane oxygenation.

New developments in the pathogenesis and treatment of neonatal pulmonary hypertension

New developments in the pathogenesis and treatment of neonatal pulmonary hypertension

New developments in the pathogenesis and treatment of neonatal pulmonary hypertension

New developments in the pathogenesis and treatment of neonatal pulmonary hypertension

Nitric oxide in the treatment of neonatal pulmonary hypertension

This study describes the effects of nitric oxide in newborns with persistent pulmonary hypertension. We studied 9 infants with severe respiratory failure characterized by hypoxemia and pulmonary hypertension. All infants met ECMO criteria and the oxygenation index (OI) was greater than 25. Mean birth weight was 2698 -/+ 661 g and gestational age was 36.4 -/+ 2.6 weeks. Nitric oxide was administered in a Y circuit in the inspiratory line of the mechanical ventilator. Nitric oxide and NO2 concentrations were monitored with electrochemical analyzers (PACI and PACII-Draeger). Pulmonary hypertension was diagnosed with clinical and echocardiografic criteria, with detection of right to left shunt with color doppler. All patients showed a dramatic improvement in oxigenation after nitric oxide administration. The drug reduced the mean OI, which was 48.5 before its administration, to 17.7 after 30', 14.1 after 6 hours, and 10.5 after 12 hours. We observed in all patients a reduction in pulmonary vascular resistance, reversal of the right to left shunt without any effects on systemic arterial pressure. Metahemoglobin levels did not reach 1.5% in any patient. Only one out of the 9 patients died, after reversal of the pulmonary hypertension, from other complications of perinatal asphyxia. Our data show that nitric oxide is a promising drug in the treatment of neonatal pulmonary hypertension and that it may reduce the need of ECMO in severe respiratory failure.

The role of nitric oxide in the treatment of neonatal pulmonary hypertension.

Nitric oxide production appears to be decreased in infants with persistent pulmonary hypertension (PPHN). Inhaled nitric oxide may improve oxygenation by two mechanisms: increased pulmonary blood flow and improved ventilation-perfusion matching. Nitric oxide inhalation has been tested in newborns with PPHN, congenital heart diseases, and bronchopulmonary dysplasia. We present a review of the articles concerning inhaled nitric oxide for infants with PPHN. Overall, 59% of the neonates had an initial improvement in oxygenation in response to nitric oxide inhalation. A sustained response was observed in 60% of the infants. Patients with extrapulmonary shunting, clear chest radiographs, and adequate lung volume seem to have a better response, whereas patients with congenital diaphragmatic hernia, severe sepsis, and alveolar capillary dysplasia are more likely to fail. To define the benefit-risk ratio, six prospective randomized trials are currently in progress.

Adaptation of fetal pulmonary blood flow to local infusion of tolazoline.

Although tolazoline is the most commonly used drug in the treatment of neonatal pulmonary hypertension, its mode of action and efficacy remain incompletely understood. In order to study the effects of tolazoline on a high resistance pulmonary circulation and to better understand mechanisms that control pulmonary vascular tone and reactivity in the fetus, we infused tolazoline either continuously or as bolus into the left pulmonary artery of 15 chronically instrumented, normoxic fetal lambs during late gestation. The vasodilatory effects of bolus injections of tolazoline (2.5 mg) were inhibited by the prior administration of the histaminergic receptor blockers, cimetidine (56%), diphenhydramine (56%), or both (100%). During the continuous infusion of tolazoline (4.5 mg/h for 9 min), pulmonary blood flow to the left lung increased from 61 +/- 6 ml/min (mean +/- SE; control) to 100 +/- 10 (peak) at 30 min (p less than 0.001). However, following this initial vasodilatation, pulmonary blood flow steadily decreased toward control values by 90 min, despite the continued infusion of tolazoline (p less than 0.001). Although the calcium channel blocker, verapamil, and the alpha-adrenergic blocker, phentolamine, had little effect on fetal pulmonary blood flow when infused alone, both drugs increased the vasodilatory response to tolazoline (p less than 0.001). We conclude that tolazoline effects pulmonary vasodilatation by a histaminergic mechanism and that subsequent refractoriness to the drug is a calcium-dependent process which may be partially mediated by an alpha-adrenergic mechanism.

Prostacyclin in the treatment of neonatal pulmonary hypertension

PERSISTENT pulmonary hypertension often complicates a variety of neonatal distrubances, 1 leads to right-to-left shunting across the ductus arteriosus or foramen ovale, and may thereby cause or exacerbate neonatal hypoxemia. ~ Although vasodilating agents, such as tolazoline, have been used with variable success in the treatment of neonatal pulmonary vasoconstriction, 2 a generally acceptable therapy is still lacking. Prostacyclin (epoprostenol, PGI2) is a potent vasodilatory and antiaggregatory agent that may participate in postnatal pulmonary vasodilation. 3, 4 It has been used successfully in the management of pulmonary hypertension in adults 5 and in one newborn infant. 6 We describe five newborn infants with pulmonary hypertension who received intravascular infusion of PGI2.