Variation in the definition of pulmonary hypertension and clinical indications for the use of nitric oxide in neonatal clinical trials

Inhaled nitric oxide in preterm neonates with preterm prelabour rupture of membranes, a systematic review

AIM

To perform a systematic literature review to determine the effect of inhaled nitric oxide (iNO) on oxygenation, mortality and morbidity in preterm neonates with preterm prelabour rupture of membranes (PPROM) and early hypoxaemic respiratory failure (HRF).

METHODS

MEDLINE, Embase, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Web of Science, Zetoc and ProQuest were searched. Studies including neonates <34 weeks' gestation with PPROM, oligohydramnios or pulmonary hypoplasia and HRF in the first 28 days of life treated with iNO were included. Studies were critically appraised and assessed for potential risk of bias using standardised checklists.

RESULTS

Six hundred and two records remained after duplicates were removed. Seven studies were included in the critical appraisal process. Quality of available evidence was very low to low. Six studies described an improvement in oxygenation after commencement of iNO. One hundred and three of 284 (36%) neonates exposed to iNO died. Seventy-seven of 92 (84%) neonates that had an echocardiogram performed before commencement of iNO had pulmonary hypertension (PH) present.

CONCLUSION

iNO may improve oxygenation when standard care fails. Improvement in oxygenation is likely associated with increase in survival. Survival may lead to an increase in morbidity. Efficacy of iNO in this cohort is likely secondary to relatively high prevalence of PH.

Pulmonary Vascular Remodeling in Pulmonary Hypertension

Pulmonary vascular remodeling is the critical structural alteration and pathological feature in pulmonary hypertension (PH) and involves changes in the intima, media and adventitia. Pulmonary vascular remodeling consists of the proliferation and phenotypic transformation of pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs) of the middle membranous pulmonary artery, as well as complex interactions involving external layer pulmonary artery fibroblasts (PAFs) and extracellular matrix (ECM). Inflammatory mechanisms, apoptosis and other factors in the vascular wall are influenced by different mechanisms that likely act in concert to drive disease progression. This article reviews these pathological changes and highlights some pathogenetic mechanisms involved in the remodeling process.

Controversies in neonatology: The efficacy of inhaled nitric oxide in preterm infants with persistent pulmonary hypertension

Introduction: There is limited and conflicting information in literature regarding use of inhaled nitric oxide (iNO) in preterm infants. In this study we examined the characteristics of preterm infants with persistent pulmonary hypertension (PHT) who responded and did not respond to iNO therapy . Material and Method: We retrospectively reviewed data of infants

Relation between endothelial nitric oxide synthase genetic polymorphisms and pulmonary arterial hypertension in newborns with congenital heart disease

OBJECTIVE

To investigate whether endothelial nitric oxide synthase (eNOS) rs1799983, rs2070744, and rs61722009 gene polymorphisms are associated with pulmonary arterial hypertension (PAH) in South Fujian newborns with congenital heart disease (CHD).

METHODS

Genotyping for the eNOS rs1799983, rs2070744, and rs61722009 polymorphisms was performed using Sanger sequencing in 50 newborns with PAH secondary to CHD [CHD PAH (+)], 52 newborns with CHD without PAH [CHD PAH (-)], and 60 healthy controls.

RESULTS

The genotype and allele frequency distributions of eNOS rs1799983, rs2070744, and rs61722009 were similar between CHD and healthy controls (P > .05). The frequencies of the eNOS rs1799983 G/T allele were 85% and 15% in the CHD PAH (+) group and 96.15% and 3.85% in the CHD PAH (-) group, the frequency of the T allele was higher in the CHD PAH (+) group than in the CHD PAH (-) group(P< .05), and patients with the GT/TT genotypes of eNOS rs1799983 may present higher PAH (OR = 4.412, 95%CI:1.411-13.797, P= .011). Newborns with the GT/TT genotypes had decreased plasma NO production compared to newborns with the GG genotype (P< .01), and NO levels in the CHD PAH (+) group were significantly lower than those in the CHD PAH (-) group (P < .05).

CONCLUSION

The T allele could be a risk factor for PAH in newborns with CHD in South Fujian through decreased levels of nitric oxide production by the endothelium.

Giant omphalocele associated pulmonary hypertension: A retrospective study

BACKGROUND

Omphalocele is a common congenital defect of the abdominal wall, management of giant omphalocele (GO) is particularly for pediatric surgeons and neonatologists worldwide. The current study aimed to review and summarize the clinical features and prognosis in neonates with GO complicated with pulmonary hypertension (PH), which is associated with increased mortality, while in hospital.

MATERIALS AND METHODS

Medical records of infants with GO between July 2015 and June 2020 were retrospectively analyzed. The patients enrolled were divided into PH and non-PH groups based on the presence or absence of PH, and patients with PH were divided into death and survival groups based on survival status. Clinical characteristics and outcomes were compared between groups, respectively. The risk factors for PH were analyzed by binary logistic regression.

RESULTS

In total, 67 neonates were identified as having GO and 24 (35.8%) were complicated with PH. Infants with PH were associated with intubation within 24 h after birth (p = 0.038), pulmonary dysplasia (p = 0.020), presence of patent ductus arteriosus (PDA; p = 0.028), a staged operation (p = 0.002), longer mechanical ventilation days (p < 0.001), oxygen requirement days (p < 0.001), parenteral nutrition (PN) days (p < 0.001), length of neonatal intensive care unit (NICU) or hospital stay (p = 0.001 and 0.002, respectively), and mortality (p = 0.001). The results of multivariable logistic regression analysis revealed that a staged operation was independently associated with PH. In addition, PH patients with lower birth weight, higher peak of pulmonary arterial systolic pressure, and refractory to pulmonary vasodilators (PVD) had increased mortality.

CONCLUSION

Pulmonary hypertension is a serious complication and significantly increases the mortality and morbidities in infants with a GO. In addition, early and serial assessment of PH by echocardiography should be a routine screening scheme, especially in the neonatal omphalocele population who required a staged surgical repair. Clinicians should be aware that infants with PH who had low weight, severe and refractory PH have a higher risk of death.