Advances in the diagnosis and management of persistent pulmonary hypertension of the newborn

Current diagnosis and treatment practice for pulmonary hypertension in bronchopulmonary dysplasia-A survey study in Germany (PUsH BPD)

Pulmonary hypertension (PH) is the most severe complication in preterm infants with bronchopulmonary dysplasia (BPD) and associated with significant mortality. Diagnostic and treatment strategies, however, still lack standardization. By the use of a survey study (PH in BPD), we assessed clinical practice (diagnosis, treatment, follow-up) in preterm infants with early postnatal persistent pulmonary hypertension of the newborn (PPHN) as well as at risk for or with established BPD-associated PH between 06/2018 and 10/2020 in two-thirds of all German perinatal centers with >70 very low birthweight infants/year including their cardiology departments and outpatient units. Data were analyzed descriptively by measures of locations and distributional shares. In routine postnatal care, clinical presentation and echocardiography were reported as the main diagnostic modalities to screen for PPHN in preterm infants, whereas biomarkers brain natriuretic peptide/N-terminal pro b-type natriuretic peptide were infrequently used. For PPHN treatment, inhaled nitric oxide was used in varying frequency. The majority of participants agreed to prescribe diuretics and steroids (systemic/inhaled) for infants at risk for or with established BPD-associated PH and strongly agreed on recommending respiratory syncytial virus immunization and the use of home monitoring upon discharge. Reported oxygen saturation targets, however, varied in these patients in in- and outpatient care. The survey reveals shared practices in diagnostic and therapeutic strategies for preterms with PPHN and BPD-associated PH in Germany. Future studies are needed to agree on detailed echo parameters and biomarkers to diagnose and monitor disease next to a much-needed agreement on the use of pulmonary vasodilators, steroids, and diuretics as well as target oxygen saturation levels.

Association between the development of bronchopulmonary dysplasia and platelet transfusion: a protocol for a systematic review and meta-analysis

Background

There is a lack of consensus on the management of thrombocytopenia in preterm infants, and the threshold for prophylactic platelet transfusion varies widely among clinicians and institutions. Reports in animal models suggested that platelets may play a relevant role in lung alveolarization and regeneration. Bronchopulmonary dysplasia (BPD) is a severe respiratory condition with a multifactorial origin that affects infants born at the early stages of lung development. Recent randomized controlled trials on the platelets count threshold for prophylactic transfusions in preterm infants with thrombocytopenia suggest that a higher exposition to platelet transfusion may increase the risk of BPD. Here, we report a protocol for a systematic review, which aims to assist evidence-based clinical practice and clarify if the administration of platelet products may be associated with the incidence of BPD and/or death in preterm infants.

Methods

MEDLINE, Embase, Cochrane databases, and sources of gray literature for conference abstracts and trial registrations will be searched with no time or language restrictions. Case-control studies, cohort studies, and nonrandomized or randomized trials that evaluated the risk for BPD and/or death in preterm infants exposed to platelet transfusion will be included. Data from studies that are sufficiently similar will be pooled as appropriate. Data extraction forms will be developed a priori. Observational studies and nonrandomized and randomized clinical trials will be analyzed separately. Odds ratio with 95% confidence interval (CI) for dichotomous outcomes and the mean difference (95% CI) for continuous outcomes will be combined. The expected heterogeneity will be accounted for using a random-effects model. Subgroup analysis will be performed based on a priori-determined covariate of interest. In case of sufficient homogeneity of interventions and outcomes evaluated, results from subgroups of studies will be pooled together in a meta-analysis.

Discussion

This systematic review will investigate the association of BPD/death with platelet components administration in preterm infants, and, consequently, it will provide reliable indications for the evidence-based management of premature patients with thrombocytopenia.

Correlation of ABO blood groups with treatment response and efficacy in infants with persistent pulmonary hypertension of the newborn treated with inhaled nitric oxide

OBJECTIVE

Not all infants with persistent pulmonary hypertension of the newborn (PPHN) respond to inhaled nitric oxide (iNO) therapy, as it is known to improve oxygenation in only 50% to 60% of cases. In this study, we investigated whether ABO blood groups were a relevant factor affecting the improvement of oxygenation by nitric oxide (NO) therapy in infants with PPHN.

METHODS

This study was a retrospective, multicenter, and cohort-controlled trial that involved 37 medical units. Infants with PPHN who met the inclusion criteria and were treated with NO (a vasodilator) alone from July 1, 2015, to June 30, 2020, were selected and assigned into three groups: blood type A, blood type B, and blood type O (there were only 7 cases of blood type AB, with a small number of cases, and therefore, blood type AB was excluded for further analysis). The response to iNO therapy was defined as an increase in the ratio of the partial pressure of arterial oxygen (PaO2)/fraction of inspired oxygen (FiO2) > 20% from the basal value after treatment. Oxygenation was assessed mainly based on the two values, oxygenation index (OI) and PaO2/FiO2. The correlation of ABO blood groups with responses to iNO therapy and their influence on the efficacy of iNO therapy was analyzed based on the collected data.

RESULTS

The highest proportion of infants with PPHN who eventually responded to iNO therapy was infants with blood type O. Infants with blood type O more readily responded to iNO therapy than infants with blood type B. Oxygenation after iNO treatment group was optimal in the blood type O group and was the worst in the blood type A group among the three groups. Infants with blood type O showed better efficacy than those with blood types A and B.

CONCLUSION

ABO blood groups are correlated with responses to iNO therapy in infants with PPHN, and different blood groups also affect the efficacy of NO therapy in infants with PPHN. Specifically, infants with blood type O have a better response and experience the best efficacy to iNO therapy.

Biomarkers in premature calves with and without respiratory distress syndrome

BACKGROUND

Approaches to the evaluation of pulmonary arterial hypertension (PAH) in premature calves by using lung-specific epithelial and endothelial biomarkers are needed.

OBJECTIVE

To investigate the evaluation of PAH in premature calves with and without respiratory distress syndrome (RDS) by using lung-specific epithelial and endothelial biomarkers and determine the prognostic value of these markers in premature calves.

ANIMALS

Fifty premature calves with RDS, 20 non-RDS premature calves, and 10 healthy term calves.

METHODS

Hypoxia, hypercapnia, and tachypnea were considered criteria for RDS. Arterial blood gases (PaO2 , PaCO2 , oxygen saturation [SO2 ], base excess [BE], and serum lactate concentration) were measured to assess hypoxia. Serum concentrations of lung-specific growth differentiation factor-15 (GDF-15), asymmetric dimethylarginine (ADMA), endothelin-1 (ET-1), vascular endothelial growth factor (VEGF), and surfactant protein D (SP-D) were measured to assess PAH.

RESULTS

Arterial blood pH, PaO2 , SO2 , and BE of premature calves with RDS were significantly lower and PaCO2 and lactate concentrations higher compared to non-RDS premature and healthy calves. The ADMA and SP-D concentrations of premature calves with RDS were lower and serum ET-1 concentrations higher than those of non-RDS premature and healthy calves. No statistical differences for GDF-15 and VEGF were found among groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

Significant increases in serum ET-1 concentrations and decreases in ADMA and SP-D concentrations highlight the utility of these markers in the diagnosis of PAH in premature calves with RDS. Also, we found that ET-1 was a reliable diagnostic and prognostic biomarker for PAH and predicting mortality in premature calves.

Pediatric Pulmonary Hypertension: Definitions, Mechanisms, Diagnosis, and Treatment

Pediatric pulmonary hypertension (PPH) is a multifactorial disease with diverse etiologies and presenting features. Pulmonary hypertension (PH), defined as elevated pulmonary artery pressure, is the presenting feature for several pulmonary vascular diseases. It is often a hidden component of other lung diseases, such as cystic fibrosis and bronchopulmonary dysplasia. Alterations in lung development and genetic conditions are an important contributor to pediatric pulmonary hypertensive disease, which is a distinct entity from adult PH. Many of the causes of pediatric PH have prenatal onset with altered lung development due to maternal and fetal conditions. Since lung growth is altered in several conditions that lead to PPH, therapy for PPH includes both pulmonary vasodilators and strategies to restore lung growth. These strategies include optimal alveolar recruitment, maintaining physiologic blood gas tension, nutritional support, and addressing contributing factors, such as airway disease and gastroesophageal reflux. The outcome for infants and children with PH is highly variable and largely dependent on the underlying cause. The best outcomes are for neonates with persistent pulmonary hypertension (PPHN) and reversible lung diseases, while some genetic conditions such as alveolar capillary dysplasia are lethal. © 2021 American Physiological Society. Compr Physiol 11:2135-2190, 2021.

Utility of Low Dose Vasopressin for Persistent Pulmonary Hypertension of Newborn with Catecholamine Refractory Shock

OBJECTIVE

To evaluate the effect of low dose vasopressin on the hemodynamics of neonates with persistent pulmonary hypertension and catecholamine refractory shock.

METHODS

This retrospective study was conducted in a level III NICU of a tertiary care teaching hospital, south India. Eighteen neonates with hypoxemic respiratory failure due to persistent pulmonary hypertension of newborn with catecholamine refractory shock were studied. Neonates were managed for hypotension with conventional inotropic support with the additional use of low dose vasopressin (LDV). Effect of vasopressin on oxygenation index (OI), blood pressure, duration of inotropic usage and survival was evaluated.

RESULTS

Mean OI was 38.2 ± 4.9, and mean blood pressure was 30.7 ± 5.3 mmHg before the start of vasopressin. Initiation of LDV (0.0003 ± 0.0001 IU/kg/min) for a median duration 36.4 ± 17.9 h was followed by a reduction in OI (p < 0.001), control of hypotension (p < 0.001), reduction in lactic acidosis (p < 0.001) and decline in inotropic support.

CONCLUSIONS

In resource-restricted settings, LDV may be useful as a rescue therapy for persistent pulmonary hypertension of newborn with catecholamine refractory shock.

B-natriuretic peptide serum levels in neonates with persistent pulmonary hypertension

Background

Better management of persistent pulmonary hypertension of neonates (PPHN) required new markers that can predict the response of patient to treatment and thus influence the medical decision to avoid short-term and long-term adverse effects. Hence, we aimed to evaluate B-natriuretic peptide (BNP) serum levels in neonates with PPHN and to correlate its levels with disease severity and response to treatment.

Patients and methods

The study included 60 neonates (30 PPHN patients and 30 healthy subjects). BNP was assessed, using the ELISA technique, at admission and after 4 days of treatment.

Results

Initial serum BNP levels were significantly higher in patients compared to controls (p < 0.001). Patients with mild severity showed lower BNP levels compared to patients with moderate severity, while patients with moderate severity showed decreased levels in comparison to severe cases (p < 0.001). The group of patients who showed remission after 4 days of treatment had lower pre-treatment and post-treatment BNP levels, compared to patients who showed incomplete remission. Initial levels of BNP showed strong positive correlations with pulmonary artery pressure (PAP) and oxygenation index (OI) before treatment (r = 0.9, p < 0.001 and r = 0.85, p = 0.001), while BNP after treatment showed moderate positive correlations with PAP before treatment (r = 0.6, p = 0.001) and OI before treatment (r = 0.6, p = 0.001). Analysis of the ROC curve revealed an AUC of 0.83with CI = 0.7–0.98 and p = 0.003.

Conclusions

BNP may play a role in the pathogenesis of PPHN, and BNP serum level can be used as a marker to detect disease severity and predict response to treatment.

Prenatal prediction of neonatal haemodynamic adaptation after maternal hyperoxygenation

Abstract

The reactivity of the pulmonary vascular bed to the administration of oxygen is well established in the post-natal circulation. The vasoreactivity demonstrated by the fetal pulmonary artery Doppler waveform in response to maternal hyperoxia has been investigated. We sought to investigate the relationship between the reactivity of the fetal pulmonary arteries to hyperoxia and subsequent neonatal cardiac function in the early newborn period.

Methods

This explorative study with convenience sampling measured pulsatility index (PI), resistance index (RI), acceleration time (AT), and ejection time (ET) from the fetal distal branch pulmonary artery (PA) at baseline and following maternal hyperoxygenation (MH). Oxygen was administered for 10 min at a rate of 12 L/min via a partial non-rebreather mask. A neonatal functional echocardiogram was performed within the first 24 h of life to assess ejection fraction (EF), left ventricular output (LVO), and neonatal pulmonary artery AT (nPAAT). This study was conducted in the Rotunda Hospital, Dublin, Ireland.

Results

Forty-six women with a singleton pregnancy greater than or equal to 31 weeks’ gestational age were prospectively recruited to the study. The median gestational age was 35 weeks. There was a decrease in fetal PAPI and PARI following MH and an increase in fetal PAAT, leading to an increase in PA AT:ET. Fetuses that responded to hyperoxygenation were more likely to have a higher LVO (135 ± 25 mL/kg/min vs 111 ± 21 mL/kg/min, p < 0.01) and EF (54 ± 9% vs 47 ± 7%,p = 0.03) in the early newborn period than those that did not respond to MH prenatally. These findings were not dependent on left ventricular size or mitral valve (MV) annular diameter but were related to an increased MV inflow. There was no difference in nPAAT.

Conclusion

These findings indicate a reduction in fetal pulmonary vascular resistance (PVR) and an increase in pulmonary blood flow and left atrial return following MH. The fetal response to hyperoxia reflected an optimal adaptation to postnatal life with rapid reduction in PVR increasing measured cardiac output.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-020-03403-y.

Biomarkers of Inflammation and Lung Recovery in Extracorporeal Membrane Oxygenation Patients With Persistent Pulmonary Hypertension of the Newborn: A Feasibility Study

OBJECTIVES

Extracorporeal membrane oxygenation is a treatment for Persistent Pulmonary Hypertension of the Newborn with high mortality.

HYPOTHESIS

the extracorporeal membrane oxygenation circuit results in inflammatory responses that mitigate against successful weaning.

DESIGN

Single-center prospective observational feasibility study.

SETTING

PICU.

PATIENTS

Twenty-four neonates requiring extracorporeal membrane oxygenation support for Persistent Pulmonary Hypertension of the Newborn.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The reference outcome was death or more than 7 days of extracorporeal membrane oxygenation support. Other outcomes included serial measures of plasma-free hemoglobin and markers of its metabolism, leucocyte, platelet and endothelial activation, and biomarkers of inflammation. Of 24 participants recruited between February 2016 and June 2017, 10 died or required prolonged extracorporeal membrane oxygenation support. These patients were sicker at baseline with higher levels of plasma-free hemoglobin within 12 hours of cannulation (geometric mean ratio, 1.92; 95% CIs, 1.00-3.67; p = 0.050) but not thereafter, versus those requiring less than 7 days extracorporeal membrane oxygenation. Serum haptoglobin concentrations were significantly elevated in both groups. Patients who died or required prolonged extracorporeal membrane oxygenation support demonstrated elevated levels of platelet-leucocyte aggregation, but decreased concentrations of mediators of the inflammatory response: interleukin-8, C-reactive protein, and tumor necrosis factor α.

CONCLUSIONS

Clinical status at baseline and not levels of plasma-free hemoglobin or the systemic inflammatory response may determine the requirement for prolonged extracorporeal membrane oxygenation support in neonates.

Management of Multi Organ Dysfunction in Neonatal Encephalopathy

Neonatal Encephalopathy (NE) describes neonates with disturbed neurological function in the first post-natal days of life. NE is an overall term that does not specify the etiology of the encephalopathy although it often involves hypoxia-ischaemia. In NE, although neurological dysfunction is part of the injury and is most predictive of long-term outcome, these infants may also have multiorgan injury and compromise, which further contribute to neurological impairment and long-term morbidities. Therapeutic hypothermia (TH) is the standard of care for moderate to severe NE. Infants with NE may have co-existing immune, respiratory, endocrine, renal, hepatic, and cardiac dysfunction that require individualized management and can be impacted by TH. Non-neurological organ dysfunction not only has a negative effect on long term outcome but may also influence the efficacy of treatments in the acute phase. Post resuscitative care involves stabilization and decisions regarding TH and management of multi-organ dysfunction. This management includes detailed neurological assessment, cardio-respiratory stabilization, glycaemic and fluid control, sepsis evaluation and antibiotics, seizure identification, and monitoring and responding to biochemical and coagulation derangements. The emergence of new biomarkers of specific organ injury may have predictive value and improve the definition of organ injury and prognosis. Further evidence-based research is needed to optimize management of NE, prevent further organ dysfunction and reduce neurodevelopmental impairment.

Change in neonatal resuscitation guidelines and trends in incidence of meconium aspiration syndrome in California

OBJECTIVE

To describe trends in the incidence and severity of meconium aspiration syndrome (MAS) around the release of revised Neonatal Resuscitation Program (NRP) guidelines in 2016.

STUDY DESIGN

The California Perinatal Quality Care Collaborative database was queried for years 2013-2017 to describe the incidence and outcomes of infants with MAS. Results were analyzed based on both individual years and pre- vs. post-guideline epochs (2013-15 vs. 2017).

RESULT

Incidence of MAS decreased significantly from 2013-15 to 2017 (1.02 to 0.78/1000 births, p < 0.001). Among infants with MAS, delivery room intubations decreased from 2013-15 to 2017 (44.3 vs. 35.1%; p = 0.005), but similar proportion of infants required invasive respiratory support (80.1 vs. 80.8%), inhaled nitric oxide (28.8 vs. 28.4%) or extracorporeal membrane oxygenation (0.81 vs. 0.35%).

CONCLUSION

While the study design precludes confirmation of implementation of the recent NRP recommendation, there was no increase in the incidence or severity of MAS following its release.

Gestational Hypoxia and Programing of Lung Metabolism

Gestational hypoxia is a risk factor in the development of pulmonary hypertension in the newborn and other sequela, however, the mechanisms associated with the disease remain poorly understood. This review highlights disruption of metabolism by antenatal high altitude hypoxia and the impact this has on pulmonary hypertension in the newborn with discussion of model organisms and human populations. There is particular emphasis on modifications in glucose and lipid metabolism along with alterations in mitochondrial function. Additional focus is placed on increases in oxidative stress and the progression of pulmonary vascular disease in the newborn and on the need for further exploration using a combination of contemporary and classical approaches.

Current understanding and perioperative management of pediatric pulmonary hypertension

Pediatric pulmonary hypertension is a complex disease with multiple, diverse etiologies affecting the premature neonate to the young adult. Pediatric pulmonary arterial hypertension, whether idiopathic or associated with congenital heart disease, is the most commonly discussed form of pediatric pulmonary hypertension, as it is progressive and lethal. However, neonatal forms of pulmonary hypertension are vastly more frequent, and while most cases are transient, the risk of morbidity and mortality in this group deserves recognition. Pulmonary hypertension due to left heart disease is another subset increasingly recognized as an important cause of pediatric pulmonary hypertension. One aspect of pediatric pulmonary hypertension is very clear: anesthetizing the child with pulmonary hypertension is associated with a significantly heightened risk of morbidity and mortality. It is therefore imperative that anesthesiologists who care for children with pulmonary hypertension have a firm understanding of the pathophysiology of the various forms of pediatric pulmonary hypertension, the impact of anesthesia and sedation in the setting of pulmonary hypertension, and anesthesiologists' role as perioperative experts from preoperative planning to postoperative disposition. This review summarizes the current understanding of pediatric pulmonary hypertension physiology, preoperative risk stratification, anesthetic risk, and intraoperative considerations relevant to the underlying pathophysiology of various forms of pediatric pulmonary hypertension.

An Analysis of Time to Improvement in Oxygenation in Japanese Preterm and Late Preterm or Term Neonates With Hypoxic Respiratory Failure and Pulmonary Hypertension

PURPOSE

We analyzed data from an ongoing registry to determine time to improvement in oxygenation in preterm and late preterm or term neonates with hypoxic respiratory failure and pulmonary hypertension receiving inhaled nitric oxide (iNO) in Japan.

METHODS

Registry neonates received iNO ≤7 days after birth (February 26, 2010, to October 9, 2012). Efficacy and safety profile data were collected up to 96 h after iNO initiation and, if necessary, every 24 h thereafter and before iNO discontinuation. Patients were stratified by gestational age (GA), oxygenation index (OI), and shunt direction at baseline.

FINDINGS

Data were evaluated for 1106 neonates (431 with a GA <34 weeks and 675 with a GA of ≥34 weeks). Sixty percent of patients had improved OI; rates were similar for those with GAs of <34 versus ≥34 weeks (61% vs 59%). Overall, mean time to improvement was 11.4 h and tended to be shorter in the groups with a GA <34 weeks versus ≥34 weeks (9.2 vs 12.9 h). Thirty percent of responding neonates required >1 h to achieve improvement in oxygenation. Neonates with higher baseline OI had the greatest decrease in OI during the first hour of treatment. The mortality rate was higher among iNO-treated patients with a baseline OI ≥25 versus those with OI ≥15 to <25 (25% vs 12%; P = 0.0073).

IMPLICATIONS

iNO treatment provided acute, sustained improvement in oxygenation in neonates with GAs <34 and ≥34 weeks; 70% of patients had improvement within 1 h, but the remaining 30% took >1 h to respond. Initiation of iNO at lower OIs was associated with reduced mortality compared with higher OI.

The Burden of Hypoxic Respiratory Failure in Preterm and Term/Near-term Infants in the United States 2011-2015

OBJECTIVES

This study quantified the burden of hypoxic respiratory failure (HRF)/persistent pulmonary hypertension of newborn (PPHN) in preterm and term/near-term infants (T/NTs) by examining health care resource utilization (HRU) and charges in the United States.

METHODS

Preterms and T/NTs (≤34 and >34 weeks of gestation, respectively) having HRF/PPHN, with/without meconium aspiration in inpatient setting from January 1, 2011-October 31, 2015 were identified from the Vizient database (first hospitalization=index hospitalization). Comorbidities, treatments, HRU, and charges during index hospitalization were evaluated among preterms and T/NTs with HRF/PPHN. Logistic regression was performed to evaluate mortality-related factors.

RESULTS

This retrospective study included 504 preterms and 414 T/NTs with HRF/PPHN. Preterms were more likely to have respiratory distress syndrome, neonatal jaundice, and anemia of prematurity than T/NTs. Preterms had significantly longer inpatient stays (54.1 vs 29.0 days), time in a neonatal intensive care unit (34.1 vs 17.5 days), time on ventilation (4.7 vs 2.2 days), and higher total hospitalization charges ($613 350 vs $422 558) (all P<0.001). Similar rates were observed for use of antibiotics (96.2% vs 95.4%), sildenafil (9.5% vs 8.2%), or inhaled nitric oxide (93.8% vs 94.2%). Preterms had a significantly higher likelihood of mortality than T/NTs (odds ratio: 3.6, 95% confidence interval: 2.3-5.0).

CONCLUSIONS

The findings of more severe comorbidities, higher HRU, hospitalization charges, and mortality in preterms than in T/NTs underscore the significant clinical and economic burden of HRF/PPHN among infants. The results show significant unmet medical need; further research is warranted to determine new treatments and real-world evidence for improved patient outcomes.

Umbilical cord blood metabolomics reveal distinct signatures of dyslipidemia prior to bronchopulmonary dysplasia and pulmonary hypertension

Pulmonary hypertension (PH) is a common consequence of bronchopulmonary dysplasia (BPD) and remains a primary contributor to increased morbidity and mortality among preterm infants. Unfortunately, at the present time, there are no reliable early predictive markers for BPD-associated PH. Considering its health consequences, understanding in utero perturbations that lead to the development of BPD and BPD-associated PH and identifying early predictive markers is of utmost importance. As part of the discovery phase, we applied a multiplatform metabolomics approach consisting of untargeted and targeted methodologies to screen for metabolic perturbations in umbilical cord blood (UCB) plasma from preterm infants that did ( n = 21; cases) or did not ( n = 21; controls) develop subsequent PH. A total of 1,656 features were detected, of which 407 were annotated by metabolite structures. PH-associated metabolic perturbations were characterized by reductions in major choline-containing phospholipids, such as phosphatidylcholines and sphingomyelins, indicating altered lipid metabolism. The reduction in UCB abundances of major choline-containing phospholipids was confirmed in an independent validation cohort consisting of UCB plasmas from 10 cases and 10 controls matched for gestational age and BPD status. Subanalyses in the discovery cohort indicated that elevations in the oxylipins PGE1, PGE2, PGF2a, 9- and 13-HOTE, 9- and 13-HODE, and 9- and 13-KODE were positively associated with BPD presence and severity. This expansive evaluation of cord blood plasma identifies compounds reflecting dyslipidemia and suggests altered metabolite provision associated with metabolic immaturity that differentiate subjects, both by BPD severity and PH development.

Effect of various inspired oxygen concentrations on pulmonary and systemic hemodynamics and oxygenation during resuscitation in a transitioning preterm model

BACKGROUND

The Neonatal Resuscitation Program recommends initial resuscitation of preterm infants with low oxygen (O₂) followed by titration to target preductal saturations (SpO₂). We studied the effect of resuscitation with titrated O₂ on gas exchange, pulmonary, and systemic hemodynamics.

METHODOLOGY

Twenty-nine preterm lambs (127 d gestation) were randomized to resuscitation with 21% O₂ (n = 7), 100% O₂ (n = 6), or initiation at 21% and titrated to target SpO₂ (n = 16). Seven healthy term control lambs were ventilated with 21% O₂.

RESULTS

Preductal SpO₂ achieved by titrating O₂ was within the desired range similar to term lambs in 21% O₂. Resuscitation of preterm lambs with 21% and 100% O₂ resulted in SpO₂ below and above the target, respectively. Ventilation of preterm lambs with 100% O₂ and term lambs with 21% O₂ effectively decreased pulmonary vascular resistance (PVR). In contrast, preterm lambs with 21% O₂ and titrated O₂ demonstrated significantly higher PVR than term lambs on 21% O₂.

CONCLUSION(S)

Initial resuscitation with 21% O₂ followed by titration of O₂ led to suboptimal pulmonary vascular transition at birth in preterm lambs. Ventilation with 100% O₂ in preterm lambs caused hyperoxia but reduced PVR similar to term lambs on 21% O₂. Studies evaluating the initiation of resuscitation at a higher O₂ concentration followed by titration based on SpO₂ in preterm neonates are needed.

Natural History of Postnatal Cardiopulmonary Adaptation in Infants Born Extremely Preterm and Risk for Death or Bronchopulmonary Dysplasia

OBJECTIVE

To study the natural history of postnatal cardiopulmonary adaptation in infants born extremely preterm and establish its association with death or bronchopulmonary dysplasia (BPD).

STUDY DESIGN

This was a prospective, observational, cohort study of infants born extremely preterm (<29 weeks). Initial echocardiogram was performed at <48 hours of life, followed by serial echocardiograms every 24-48 hours until 14 days of life. Resolution or no resolution of pulmonary hypertension (PH) at 72-96 hours was considered normal or delayed postnatal cardiopulmonary adaptation, respectively. PH between 96 hours and 14 days was defined as subsequent PH. Elevated pulmonary artery pressure throughout the 14 days of life was considered persistent PH. BPD was assessed at 36 weeks of postmenstrual age.

RESULTS

Sixty infants were enrolled; 2 died before a sequential echocardiogram could be done at 72-96 hours. Normal and delayed cardiopulmonary adaptation were noted in 26 (45%) and 32 (55%) infants, respectively. Five patterns of postnatal cardiopulmonary adaptation were recognized: normal without subsequent PH (n = 20), normal with subsequent PH (n = 6), delayed adaptation without subsequent PH (n = 6), delayed adaptation with subsequent PH (n = 16), and persistent PH (n = 10). Infants with delayed cardiopulmonary adaptation were of lower gestation and birth weight and required prolonged ventilation and supplemental oxygen (P < .05). On multivariate analysis, the incidence of death or BPD was significantly greater among infants with delayed adaptation (P < .001).

CONCLUSION

Infants born extremely preterm have normal or delayed postnatal cardiopulmonary adaptation that can be complicated by subsequent or persistent PH. Delayed cardiopulmonary adaptation is associated independently with death or BPD.

Echocardiographic Evaluation of Transitional Circulation for the Neonatologists

The hemodynamic changes during the first few breaths after birth are probably the most significant and drastic adaptation in the human life. These changes are critical for a smooth transition of fetal to neonatal circulation. With the cord clamping, lungs take over as the source of oxygenation from placenta. A smooth transition of circulation is a complex mechanism and primarily depends upon the drop in pulmonary vascular resistance (PVR) and increase in systemic vascular resistance (SVR). Understanding the normal transition physiology and the adverse adaptation is of utmost importance to the clinicians looking after neonates. It may have a significant influence on the presentation of congenital heart defects (CHDs) in infants. Bedside echocardiography may help in understanding the transition physiology, especially the hemodynamic changes and shunting across ductus arteriosus and foramen ovale, and it may play an important role in making judicious clinical decisions based upon the altered physiology.

The Pathophysiology of Nitrogen Dioxide During Inhaled Nitric Oxide Therapy

Administration of inhaled nitric oxide (NO) with the existing compressed gas delivery systems is associated with unavoidable codelivery of nitrogen dioxide (NO2), an unwanted toxic contaminant that forms when mixed with oxygen. The NO2 is generated when NO is diluted with O2-enriched air before delivery to the patient. When NO2 is inhaled by the patient, it oxidizes protective antioxidants within the epithelial lining fluid (ELF) and triggers extracellular damage in the airways. The reaction of NO2 within the ELF triggers oxidative stress (OS), possibly leading to edema, bronchoconstriction, and a reduced forced expiratory volume in 1 second. Nitrogen dioxide has been shown to have deleterious effects on the airways of high-risk patients including neonates, patients with respiratory and heart failure, and the elderly. Minimizing co-delivery of NO2 for the next generation delivery systems will be a necessity to fully optimize the pulmonary perfusion of NO because of vasodilation, whereas minimizing the negative ventilatory and histopathological effects of NO2 exposure during inhaled NO therapy.

Therapeutic hypothermia in infants with hypoxic-ischemic encephalopathy and reversible persistent pulmonary hypertension: short-term hospital outcomes

AIM

Neonatal hypoxic ischemic encephalopathy (HIE) patients are at times accompanied by persistent pulmonary hypertension (PPHN), which is by itself another risk factor of adverse outcomes. We aimed to assess the outcome of therapeutic hypothermia (TH) in these patients whom we managed to reverse the shunt flow, as they are expected to be at much higher risk of adverse neurodevelopmental outcome.

METHODS

We reviewed the medical records of 116 HIE infants (13 with PPHN and 103 without PPHN) who underwent TH between 2012 and 2016. We analyzed the short-term hospital outcomes and brain study results (electroencephalogram and magnetic resonance imaging) of TH in these patients.

RESULTS

While infants with PPHN were significantly more likely to be outborn or have meconium aspiration syndrome, and required a longer duration of inotrope and intensive care support, electroencephalographic and brain magnetic resonance findings did not significantly differ according to PPHN status.

CONCLUSION

Based on our study, the hospital outcomes of infants with HIE accompanied by reversible PPHN who underwent TH were in general not significantly graver than those not accompanied by PPHN. Our results suggest that undergoing TH may be more beneficial in HIE infants with PPHN and the risks for possible adverse effects may not be as so high.

[Clinicopathological analysis of pulmonary vascular disease in 38 neonates died of respiratory failure]

We reviewed the data of 38 neonates who died of respiratory failure. Paraffin sections of the autopsy lung samples were examined with HE staining or immunolabeling for CD34, CD68 and CK to observe the development of the pulmonary vessels and detect potential pulmonary vascular diseases (PVDs). Five cases were identified to have PVDs, including pulmonary hypertensive vascular remodeling in 3 cases and alveolar capillary dysplasia in 2 cases. The result indicated that PVD was one of the important reasons for respiratory failure in these neonates.

[Application of humidified high-flow nasal cannula in neonates with meconium aspiration syndrome and pulmonary hypertension after extubation]

OBJECTIVE

To investigate the clinical value of humidified high-flow nasal cannula (HHFNC) as a respiratory support after extubation by comparing it with nasal continuous positive airway pressure (NCPAP) in neonates with meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of the newborn (PPHN).

METHODS

A total of 78 neonates with MAS and PPHN were randomly administered with HHFNC or NCPAP immediately after extubation. The following indices were compared between the two groups: blood gas parameters, duration of noninvasive ventilation, rate of extubation failure, and incidence of complications, such as nasal damage, abdominal distension, and intraventricular hemorrhage.

RESULTS

There were no significant differences in the rate of extubation failure, PaO₂, PCO₂, and PaO₂/FiO₂ ratio at one hour after NCPAP or HHFNC, duration of noninvasive ventilation, time to full enteral feeding, length of hospital stay, and incidence of intraventricular hemorrhage between the two groups (P>0.05). The HHFNC group had significantly lower incidence of nasal damage (5.0% vs 31.6%; P<0.05) and incidence of abdominal distension (7.5% vs 34.2%; P<0.05) than the NCPAP group.

CONCLUSIONS

Both NCPAP and HHFNC can be used as the sequential therapy for neonates with MSA and PPHN after extubation, and they both have a definite effect. As a new strategy of respiratory support, HHFNC is better tolerated, and has fewer side effects than NCPAP.

[Application of humidified high-flow nasal cannula in neonates with meconium aspiration syndrome and pulmonary hypertension after extubation]

OBJECTIVE

To investigate the clinical value of humidified high-flow nasal cannula (HHFNC) as a respiratory support after extubation by comparing it with nasal continuous positive airway pressure (NCPAP) in neonates with meconium aspiration syndrome (MAS) and persistent pulmonary hypertension of the newborn (PPHN).

METHODS

A total of 78 neonates with MAS and PPHN were randomly administered with HHFNC or NCPAP immediately after extubation. The following indices were compared between the two groups: blood gas parameters, duration of noninvasive ventilation, rate of extubation failure, and incidence of complications, such as nasal damage, abdominal distension, and intraventricular hemorrhage.

RESULTS

There were no significant differences in the rate of extubation failure, PaO2, PCO2, and PaO2/FiO2 ratio at one hour after NCPAP or HHFNC, duration of noninvasive ventilation, time to full enteral feeding, length of hospital stay, and incidence of intraventricular hemorrhage between the two groups (P>0.05). The HHFNC group had significantly lower incidence of nasal damage (5.0% vs 31.6%; P<0.05) and incidence of abdominal distension (7.5% vs 34.2%; P<0.05) than the NCPAP group.

CONCLUSIONS

Both NCPAP and HHFNC can be used as the sequential therapy for neonates with MSA and PPHN after extubation, and they both have a definite effect. As a new strategy of respiratory support, HHFNC is better tolerated, and has fewer side effects than NCPAP.

Congenital Diaphragmatic hernia - a review

Congenital Diaphragmatic hernia (CDH) is a condition characterized by a defect in the diaphragm leading to protrusion of abdominal contents into the thoracic cavity interfering with normal development of the lungs. The defect may range from a small aperture in the posterior muscle rim to complete absence of diaphragm.

The pathophysiology of CDH is a combination of lung hypoplasia and immaturity associated with persistent pulmonary hypertension of newborn (PPHN) and cardiac dysfunction. Prenatal assessment of lung to head ratio (LHR) and position of the liver by ultrasound are used to diagnose and predict outcomes. Delivery of infants with CDH is recommended close to term gestation. Immediate management at birth includes bowel decompression, avoidance of mask ventilation and endotracheal tube placement if required. The main focus of management includes gentle ventilation, hemodynamic monitoring and treatment of pulmonary hypertension followed by surgery. Although inhaled nitric oxide is not approved by FDA for the treatment of PPHN induced by CDH, it is commonly used.

Extracorporeal membrane oxygenation (ECMO) is typically considered after failure of conventional medical management for infants ≥ 34 weeks’ gestation or with weight >2 kg with CDH and no associated major lethal anomalies. Multiple factors such as prematurity, associated abnormalities, severity of PPHN, type of repair and need for ECMO can affect the survival of an infant with CDH. With advances in the management of CDH, the overall survival has improved and has been reported to be 70-90% in non-ECMO infants and up to 50% in infants who undergo ECMO.

Neonatal Morbidity After Maternal Use of Antidepressant Drugs During Pregnancy

OBJECTIVES

To estimate the rate of admissions to NICUs, as well as infants' morbidity and neonatal interventions, after exposure to antidepressant drugs in utero.

METHODS

Data on pregnancies, deliveries, prescription drug use, and health status of the newborn infants were obtained from the Swedish Medical Birth Register, the Prescribed Drug Register, and the Swedish Neonatal Quality Register. We included 741 040 singletons, born between July 1, 2006, and December 31, 2012. Of the infants, 17 736 (2.4%) had mothers who used selective serotonin reuptake inhibitors (SSRIs) during pregnancy. Infants exposed to an SSRI were compared with nonexposed infants, and infants exposed during late pregnancy were compared with those exposed during early pregnancy only. The results were analyzed with logistic regression analysis.

RESULTS

After maternal use of an SSRI, 13.7% of the infants were admitted to the NICU compared with 8.2% in the population (adjusted odds ratio: 1.5 [95% confidence interval: 1.4-1.5]). The admission rate to the NICU after treatment during late pregnancy was 16.5% compared with 10.8% after treatment during early pregnancy only (adjusted odds ratio: 1.6 [95% confidence interval: 1.5-1.8]). Respiratory and central nervous system disorders and hypoglycemia were more common after maternal use of an SSRI. Infants exposed to SSRIs in late pregnancy compared with early pregnancy had a higher risk of persistent pulmonary hypertension (number needed to harm: 285).

CONCLUSIONS

Maternal use of antidepressants during pregnancy was associated with increased neonatal morbidity and a higher rate of admissions to the NICU. The absolute risk for severe disease was low, however.

Endothelin receptor antagonists for persistent pulmonary hypertension in term and late preterm infants

BACKGROUND

Endothelin, a powerful vasoconstrictor, is one of the mediators in the causation of persistent pulmonary hypertension of the newborn (PPHN). Theoretically, endothelin receptor antagonists (ETRA) have the potential to improve the outcomes of infants with PPHN.

OBJECTIVES

To assess the efficacy and safety of ETRA in the treatment of PPHN in full-term, post-term and late preterm infants.To assess the efficacy and safety of selective ETRAs (which block only the ETA receptors) and non-selective ETRAs (which block both ETA and ETB receptors) separately.

SEARCH METHODS

CENTRAL (Cochrane Central Register of Controlled Trials), MEDLINE, EMBASE and CINAHL databases were searched until December 2015.

SELECTION CRITERIA

Randomised, cluster-randomised or quasi-randomised controlled trials were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched the literature, selected the studies, assessed the risk of bias and extracted the data. A fixed-effect model was used for meta-analysis. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

Two randomised controlled trials of ETRA met the inclusion criteria. Both studies utilized oral Bosentan. The first study was done in a setting where inhaled nitric oxide (iNO) therapy was not available. Forty-seven infants (≥ 34 weeks' gestation) were randomised to receive either Bosentan or placebo. The second study was a multicentre study where iNO therapy was the standard of care for PPHN. Twenty-one infants were randomised to receive either 'iNO plus Bosentan' or 'iNO plus placebo'.In the first study, there was no significant difference in the incidence of death before hospital discharge between the Bosentan and placebo groups (1/23 vs 3/14; RR 0.20, 95% CI 0.02 to 1.77; RD -0.17, 95% CI -0.40 to 0.06). A higher proportion of infants in the Bosentan group showed improvement in oxygenation index (OI) at the end of therapy (21/24 vs 3/15; RR 4.38, 95% CI 1.57 to 12.17; RD 0.68, 95% CI 0.43 to 0.92; number needed to treat for a beneficial outcome (NNTB) 1.5). The duration of mechanical ventilation was lower in the Bosentan group (4.3 ± 0.9 vs 11.5 ± 0.6 days; MD -7.20, 95% CI -7.64 to -6.76). There was no significant difference in adverse neurological outcomes at six months (0/23 vs 4/14; RR 0.07, 95% CI 0.00 to 1.20; RD -0.29, 95% CI -0.52 to -0.05). The study suffered from a high risk of attrition bias since 8/23 infants in the placebo group were excluded from various analyses. Since the protocol for the study could not be accessed, the study suffered from unclear risk of reporting bias.In the second study, there was no significant difference in the incidence of treatment failure needing extracorporeal membrane oxygenation (ECMO) between the 'iNO plus Bosentan' vs 'iNO plus placebo' groups (1/13 vs 0/8; RR 1.93, 95% CI 0.09 to 42.35; RD 0.08, 95% CI -0.14 to 0.30). There was no significant difference in the median time to wean from iNO ('iNO plus Bosentan': 3.7 days (95% CI 1.17 to 6.95); 'iNO plus placebo': 2.9 days (95% CI 1.26 to 4.23); P = 0.34). There were no significant differences in the OI 0, 3, 5, 12, 24, 48 and 72 hours of treatment between the groups. There were no significant differences in the time to complete weaning from mechanical ventilation (median 10.8 days (CI 3.21 to 12.21) versus 8.6 days (CI 3.71 to 9.66); P = 0.24). The study had unequal distribution to the Bosentan group (N = 13) and the placebo group (N = 8). The methods used for generating random sequence numbers and allocation concealment were unclear, resulting in unclear risk of selection bias.Both studies reported that Bosentan was well tolerated and no major adverse effects were noted. Data from the two studies was not pooled given the heterogenous nature of the clinical settings and the modalities used for the treatment of PPHN.Overall, the quality of evidence was considered low, given the small sample size of the included studies, the numerical imbalance between the groups due to randomisation and attrition, and unclear risk of bias on some of the important domains.

AUTHORS' CONCLUSIONS

There is inadequate evidence to support the use of ETRAs either as stand-alone therapy or as adjuvant to inhaled nitric oxide in PPHN. Adequately powered RCTs are needed.

Considerations in the management of hypoxemic respiratory failure and persistent pulmonary hypertension in term and late preterm neonates

Recent advances in our understanding of neonatal pulmonary circulation and the underlying pathophysiology of hypoxemic respiratory failure (HRF)/persistent pulmonary hypertension of the newborn (PPHN) have resulted in more effective management strategies. Results from animal studies demonstrate that low alveolar oxygen tension (PAO2) causes hypoxic pulmonary vasoconstriction, whereas an increase in oxygen tension to normoxic levels (preductal arterial partial pressure of oxygen (PaO2) between 60 and 80 mm Hg and/or preductal peripheral capillary oxygen saturation between 90% and 97%) results in effective pulmonary vasodilation. Hyperoxia (preductal PaO2 >80 mm Hg) does not cause further pulmonary vasodilation, and oxygen toxicity may occur when high concentrations of inspired oxygen are used. It is therefore important to avoid both hypoxemia and hyperoxemia in the management of PPHN. In addition to oxygen supplementation, therapeutic strategies used to manage HRF/PPHN in term and late preterm neonates may include lung recruitment with optimal mean airway pressure and surfactant, inhaled and intravenous vasodilators and 'inodilators'. Clinical evidence suggests that administration of surfactant or inhaled nitric oxide (iNO) therapy at a lower acuity of illness can decrease the risk of extracorporeal membrane oxygenation/death, progression of HRF and duration of hospital stay. Milrinone may be beneficial as an inodilator and may have specific benefits following prolonged exposure to iNO plus oxygen owing to inhibition of phosphodiesterase (PDE)-3A. Additionally, sildenafil, and, in selected cases, hydrocortisone may be appropriate options after hyperoxia and oxidative stress owing to their effects on PDE-5 activity and expression. Continued investigation into these and other interventions is needed to optimize treatment and improve outcomes.

The fetal circulation, pathophysiology of hypoxemic respiratory failure and pulmonary hypertension in neonates, and the role of oxygen therapy

Neonatal hypoxemic respiratory failure (HRF), a deficiency of oxygenation associated with insufficient ventilation, can occur due to a variety of etiologies. HRF can result when pulmonary vascular resistance (PVR) fails to decrease at birth, leading to persistent pulmonary hypertension of newborn (PPHN), or as a result of various lung disorders including congenital abnormalities such as diaphragmatic hernia, and disorders of transition such as respiratory distress syndrome, transient tachypnea of newborn and perinatal asphyxia. PVR changes throughout fetal life, evident by the dynamic changes in pulmonary blood flow at different gestational ages. Pulmonary vascular transition at birth requires an interplay between multiple vasoactive mediators such as nitric oxide, which can be potentially inactivated by superoxide anions. Superoxide anions have a key role in the pathophysiology of HRF. Oxygen (O2) therapy, used in newborns long before our knowledge of the complex nature of HRF and PPHN, has continued to evolve. Over time has come the discovery that too much O2 can be toxic. Recommendations on the optimal inspired O2 levels to initiate resuscitation in term newborns have ranged from 100% (pre 1998) to the currently recommended use of room air (21%). Questions remain about the most effective levels, particularly in preterm and low birth weight newborns. Attaining the appropriate balance between hypoxemia and hyperoxemia, and targeting treatments to the pathophysiology of HRF in each individual newborn are critical factors in the development of improved therapies to optimize outcomes.

Maternal use of selective serotonin-reuptake inhibitors and risk of persistent pulmonary hypertension of the newborn

Use of selective serotonin reuptake inhibitors (SSRIs) in late pregnancy has been associated with persistent pulmonary hypertension of the newborn (PPHN), a rare condition with substantial infant mortality and morbidity. Although the increase in absolute risk is small on a population level, it may be of concern to many patients. It remains unclear the extent to which the increased risks reported for PPHN are explained by the underlying maternal illness rather than the use of SSRIs.

Persistent Pulmonary Hypertension of the Newborn

Persistent pulmonary hypertension of the newborn (PPHN) is often secondary to parenchymal lung disease (such as meconium aspiration syndrome) or lung hypoplasia (with congenital diaphragmatic hernia) but can also be idiopathic. PPHN is characterized by elevated pulmonary vascular resistance, resulting in right-to-left shunting of blood and hypoxemia. The diagnosis of PPHN is based on clinical evidence of labile hypoxemia often associated with differential cyanosis and confirmed by echocardiography. Lung volume recruitment with optimal use of positive end-expiratory pressure or mean airway pressure and/or surfactant is very important in secondary PPHN due to parenchymal lung disease. Other management strategies include optimal oxygenation, avoiding respiratory and metabolic acidosis, blood pressure stabilization, sedation, and pulmonary vasodilator therapy. Failure of these measures leads to consideration of extracorporeal membrane oxygenation, although this rescue therapy is needed less frequently with advances in medical management. Randomized clinical trials with long-term follow-up are required to evaluate various therapeutic strategies in PPHN.

B-type natriuretic peptide as a parameter for pulmonary hypertension in children. A systematic review

Pulmonary hypertension (PH) is a life-threatening disease with a high mortality rate and a broad variety of underlying etiologies. The current golden standard for diagnosing PH and monitoring efficiency of treatment is right heart catheterization. As an alternative, serum biomarkers have been suggested. Cardiac troponin T (TnT), brain natriuretic peptide (BNP), and NT-proBNP seem the most potential. The aim of this systematic review was to evaluate the current literature on the prognostic value of these biomarkers in children with PH and their usefulness as a diagnostic tool. A systematic literature search yielded 14 studies on patients ≤18 years with proven PH with (NT-pro)BNP or TnT as primary outcome. TnT is suggested to be a promising biomarker, but its usefulness in clinical practice has not been proven. The levels of (NT-pro)BNP seemed to be reliable within one PH category, but differed significantly between categories. NT-proBNP showed a good correlation with mortality and might have a prognostic value.

CONCLUSION

The lack of absolute levels makes (NT-pro)BNP unsuitable as a diagnostic marker, but in view of the relative changes, it could be used to monitor patients. Further investigation should explore differences in normal (NT-pro)BNP levels between the different categories of PH.

WHAT IS KNOWN

• Pulmonary hypertension is a life-threatening disease. Diagnosis can be challenging in children; the current diagnostic options-right heart catheterization and echocardiography-are invasive and/or investigator-dependent procedures. • Biomarkers could be useful in this context because they are investigator independent and easy to obtain through blood samples. Brain natriuretic peptide (BNP) and its N-terminal cleavage product (NT-proBNP) seem to be the most promising. The value of these biomarkers in the diagnostic approach of PH has already been investigated in adults, with promising results. Pediatric studies are still scarce. What is new: • The levels of BNP and NT-proBNP in pediatric patients differ strongly between the different categories of PH. Within the same category, the levels are more or less equal. • The relative changes could render them a prognostic marker in the follow-up of a certain individual patient. At this moment there is not enough evidence to rely on BNP or NT-proBNP in clinical treatment of patients with PH.

Persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is characterized by elevated pulmonary vascular resistance resulting in right-to-left shunting of blood and hypoxemia. PPHN is often secondary to parenchymal lung disease (such as meconium aspiration syndrome, pneumonia or respiratory distress syndrome) or lung hypoplasia (with congenital diaphragmatic hernia or oligohydramnios) but can also be idiopathic. The diagnosis of PPHN is based on clinical evidence of labile hypoxemia often associated with differential cyanosis. The diagnosis is confirmed by the echocardiographic demonstration of - (a) right-to-left or bidirectional shunt at the ductus or foramen ovale and/or, (b) flattening or leftward deviation of the interventricular septum and/or, (c) tricuspid regurgitation, and finally (d) absence of structural heart disease. Management strategies include optimal oxygenation, avoiding respiratory and metabolic acidosis, blood pressure stabilization, sedation and pulmonary vasodilator therapy. Failure of these measures would lead to consideration of extracorporeal membrane oxygenation (ECMO); however decreased need for this rescue therapy has been documented with advances in medical management. While trends also note improved survival, long-term neurodevelopmental disabilities such as deafness and learning disabilities remain a concern in many infants with severe PPHN. Funded by: 1R01HD072929-0 (SL).

Antidepressant use late in pregnancy and risk of persistent pulmonary hypertension of the newborn

IMPORTANCE

The association between selective serotonin reuptake inhibitor (SSRI) antidepressant use during pregnancy and risk of persistent pulmonary hypertension of the newborn (PPHN) has been controversial since the US Food and Drug Administration issued a public health advisory in 2006.

OBJECTIVE

To examine the risk of PPHN associated with exposure to different antidepressant medication classes late in pregnancy.

DESIGN AND SETTING

Cohort study nested in the 2000-2010 Medicaid Analytic eXtract for 46 US states and Washington, DC. Last follow-up date was December 31, 2010.

PARTICIPANTS

A total of 3,789,330 pregnant women enrolled in Medicaid from 2 months or fewer after the date of last menstrual period through at least 1 month after delivery. The source cohort was restricted to women with a depression diagnosis and logistic regression analysis with propensity score adjustment applied to control for potential confounders. EXPOSURES FOR OBSERVATIONAL STUDIES: SSRI and non-SSRI monotherapy use during the 90 days before delivery vs no use.

MAIN OUTCOMES AND MEASURES

Recorded diagnosis of PPHN during the first 30 days after delivery.

RESULTS

A total of 128,950 women (3.4%) filled at least 1 prescription for antidepressants late in pregnancy: 102,179 (2.7%) used an SSRI and 26,771 (0.7%) a non-SSRI. Overall, 7630 infants not exposed to antidepressants were diagnosed with PPHN (20.8; 95% CI, 20.4-21.3 per 10,000 births) compared with 322 infants exposed to SSRIs (31.5; 95% CI, 28.3-35.2 per 10,000 births), and 78 infants exposed to non-SSRIs (29.1; 95% CI, 23.3-36.4 per 10,000 births). Associations between antidepressant use and PPHN were attenuated with increasing levels of confounding adjustment. For SSRIs, odds ratios were 1.51 (95% CI, 1.35-1.69) unadjusted and 1.10 (95% CI, 0.94-1.29) after restricting to women with depression and adjusting for the high-dimensional propensity score. For non-SSRIs, the odds ratios were 1.40 (95% CI, 1.12-1.75) and 1.02 (95% CI, 0.77-1.35), respectively. Upon restriction of the outcome to primary PPHN, the adjusted odds ratio for SSRIs was 1.28 (95% CI, 1.01-1.64) and for non-SSRIs 1.14 (95% CI, 0.74-1.74).

CONCLUSIONS AND RELEVANCE

Evidence from this large study of publicly insured pregnant women may be consistent with a potential increased risk of PPHN associated with maternal use of SSRIs in late pregnancy. However, the absolute risk was small, and the risk increase appears more modest than suggested in previous studies.

Molecular physiopathogenetic mechanisms and development of new potential therapeutic strategies in persistent pulmonary hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) is a cyanogenic plurifactorial disorder characterized by failed postnatal drop of pulmonary vascular resistance and maintenance of right-to-left shunt across ductus arteriosus and foramen ovale typical of intrauterine life. The pathogenesis of PPHN is very complex and can result from functional (vasoconstriction) or structural (arteriolar remodeling, reduced pulmonary vessels density) anomalies of pulmonary circulation. Etiopathogenetic factors heterogeneity can strongly condition therapeutical results and prognosis of PPHN that is particularly severe in organic forms that are usually refractory to selective pulmonary vasodilator therapy with inhaled nitric oxide. This paper reports the more recent acquisitions on molecular physiopathogenetic mechanisms underlying functional and structural forms of PPHN and illustrates the bases for adoption of new potential treatment strategies for organic PPHN. These strategies aim to reverse pulmonary vascular remodeling in PPHN with arteriolar smooth muscle hypertrophy and stimulate pulmonary vascular and alveolar growth in PPHN associated with lung hypoplasia.In order to restore lung growth in this severe form of PPHN, attention is focused on the results of studies of mesenchymal stem cells and their therapeutical paracrine effects on bronchopulmonry dysplasia, a chronic neonatal lung disease characterized by arrested vascular and alveolar growth and development of pulmonary hypertension.

Sildenafil Treatment of Infants With Bronchopulmonary Dysplasia-Associated Pulmonary Hypertension

OBJECTIVE

This study had 2 goals: (1) to identify clinical and demographic characteristics associated with sildenafil exposure for infants with bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH); and (2) to characterize hospital-specific treatment frequency, age at first administration, and length of sildenafil treatment.

METHODS

This retrospective cohort study used data from the Pediatric Health Information System to determine variables associated with sildenafil exposure and between-hospital variations in sildenafil utilization patterns. The study included infants with BPD-PH who were discharged between January 1, 2006, and December 31, 2013.

RESULTS

Within 36 US pediatric hospitals, 3720 infants were diagnosed with BPD, of whom 598 (16%) also had a diagnosis of PH (BPD-PH). Among infants with BPD-PH, 104 infants (17%) received sildenafil. The odds for sildenafil treatment among infants born between 25 and 26 weeks' gestational age (GA) and <24 weeks' GA, respectively, were 2.26 (95% confidence interval [CI]: 1.20-4.24) and 3.21 (95% CI: 1.66-6.21) times those of infants born at 27 to 28 weeks' GA. Severity of BPD correlated with sildenafil exposure, with adjusted odds ratios (ORs) for moderate BPD (OR: 3.03 [95% CI: 1.03-8.93]) and severe BPD (OR: 7.56 [95% CI: 2.50-22.88]), compared with mild BPD. Greater rates of sildenafil exposure were observed among small for GA neonates (OR: 2.32 [95% CI: 1.21-4.46]). The proportion of infants with BPD-PH exposed to sildenafil varied according to hospital (median: 15%; 25th-75th percentile: 0%-25%), as did the median duration of therapy (52 days; 25th-75th percentile: 28-109 days).

CONCLUSIONS

The odds of sildenafil treatment were greatest among the most premature infants with severe forms of BPD. The frequency and duration of sildenafil exposure varied markedly according to institution. Patient-centered trials for infants with BPD-PH are needed to develop evidence-based practices.

Persistent pulmonary hypertension of the newborn associated with severe congenital anemia of various etiologies

Among the many associated features of persistent pulmonary hypertension of the neonate (PPHN), severe congenital anemia has been described only occasionally and is not included in the list of conditions that may cause PPHN in the neonate. We describe the clinical course of a group of 12 full-term neonates with PPHN and congenital anemia due to congenital dyserythropoietic anemia (7/12), α thalasemia (1/12), Diamond-Blackfan (1/12), and epsilon gamma delta beta thalassemia (3/12). The association of congenital anemia and PPHN is more common than previously thought; it can exist with various etiologies and severity of anemia. Congenital anemia has not been described until now as a cause or risk factor for PPHN; it should be considered as such alone or in combination with other known causes to be recognized early and treated appropriately to improve outcome. In families with known cases of congenital anemia due to the above-mentioned diagnosis, closer prenatal follow-up should be offered to anticipate possible fetal distress and/or fetal anemia and PPHN after birth.

A comprehensive study of clinical biomarkers, use of inotropic medications and fluid resuscitation in newborns with persistent pulmonary hypertension

Persistent pulmonary hypertension of the newborn (PPHN) is associated with high morbidity and mortality. This study evaluated clinical outcomes in PPHN in relation to echocardiographic (EC) markers, score of neonatal acute physiology, perinatal extension, version II (SNAPPE II) scores, inotropic agent use, and the amount of fluid received as boluses. In this retrospective chart analysis of 98 neonates with PPHN born at >34 weeks' gestation, we compared two cohorts of newborns: those who received inhaled nitric oxide and mechanical ventilation only, and who survived to discharge (Group 1); and those who required extracorporeal membrane oxygenation (ECMO) or who died (Group 2). Of 21 EC parameters assessed, seven were significantly different between Group 1 and Group 2. Eleven (24.4%) newborns in Group 2 had decreased left ventricular (LV) function, compared with three (5.1%) in Group 1 (p = 0.011). Median SNAPPE II scores were significantly higher in Group 2 than in Group 1 (p < 0.001). Newborns in Group 2 also received a significantly higher amount of fluid as boluses during the first 7 days of hospitalization compared with Group 1 (p = 0.018). Following logistic regression analysis, only the difference in total SNAPPE II score retained statistical significance (p < 0.001); however, the total amount of fluid administered as boluses trended higher (p = 0.087) for newborns in Group 2. Our findings show that SNAPPE II scores may help guide counseling for parents of newborns with PPHN regarding the likelihood of death or the need for ECMO. Limiting fluid boluses may improve outcomes in newborns with high SNAPPE II scores and decreased LV function.

Impaired cerebral angiogenesis in the fetal lamb model of persistent pulmonary hypertension

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is associated with increased risk of neuro-developmental impairments. Whether relative fetal hypoxia during evolution of PPHN renders the fetal brain vulnerable to perinatal brain injury remains unclear. We hypothesized that in utero ductal constriction, which induces PPHN also impairs cerebral angiogenesis.

METHODS

Fetal lambs with PPHN induced by prenatal ligation of the ductus arteriosus were compared to gestation matched twin controls. Freshly collected or fixed brain specimens were analyzed by immunohistochemistry, Western blot analysis, and RT-PCR.

RESULTS

Cortical capillary density was decreased in PPHN lambs compared to controls (Glut-1, isolectin B-4 and factor VIII, n=6, p<0.05). Hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) protein levels were decreased in cortical cell lysates of PPHN lambs. PPHN increased angiopoetin-1 (Ang-1) and tyrosine-protein kinase receptor (Tie-2) protein expression while angiopoetin-2 (Ang-2) protein levels were decreased (n=6, p<0.05). PPHN did not change mRNA levels of these proteins significantly (n=6).

CONCLUSIONS

PPHN decreased cortical capillary density in fetal lamb brain. PPHN decreased the expression of proteins involved in angiogenesis. These findings suggest that PPHN is associated with impaired cortical angiogenesis.

Hydrocortisone normalizes phosphodiesterase-5 activity in pulmonary artery smooth muscle cells from lambs with persistent pulmonary hypertension of the newborn

Phosphodiesterase-5 (PDE5) is the primary phosphodiesterase in the pulmonary vasculature. It degrades cyclic guanosine monophosphate (cGMP) and inhibits cGMP-mediated vasorelaxation. We previously reported that hydrocortisone treatment decreased hyperoxia-induced PDE5 activity and markers of oxidative stress in lambs with persistent pulmonary hypertension of the newborn (PPHN) ventilated with 100% O2. The objective of our study was to determine the molecular mechanism by which hydrocortisone downregulates PDE5 and oxidative stress in fetal pulmonary artery smooth muscle cells (FPASMCs) from PPHN lambs. PPHN FPASMC were incubated for 24 hours in either 21% or 95% O2. Some cells were treated with 100 nM hydrocortisone and/or ±1 μM helenalin, an inhibitor of nuclear factor κ B (NFκB), a redox-sensitive transcription factor. Exposure to hyperoxia led to increased PDE5 activity, oxidative stress, and NFκB activity. Pretreatment of PPHN FPASMC with hydrocortisone normalized PDE5 activity, decreased cytosolic oxidative stress, increased expression of extracellular superoxide dismutase and NFκB inhibitory protein, and decreased NFκB activity. Similarly, treatment with NFκB inhibitor, helenalin, decreased PDE5 activity. These data suggest that hyperoxia activates NFκB, which in turn induces PDE5 activity in PPHN FPASMC, whereas treatment with hydrocortisone attenuates these changes by blocking reactive oxygen species-induced NFκB activity.

Update on PPHN: mechanisms and treatment

Persistent pulmonary hypertension of the newborn (PPHN) is a syndrome of failed circulatory adaptation at birth, seen in about 2/1000 live born infants. While it is mostly seen in term and near-term infants, it can be recognized in some premature infants with respiratory distress or bronchopulmonary dysplasia. Most commonly, PPHN is secondary to delayed or impaired relaxation of the pulmonary vasculature associated with diverse neonatal pulmonary pathologies, such as meconium aspiration syndrome, congenital diaphragmatic hernia, and respiratory distress syndrome. Gentle ventilation strategies, lung recruitment, inhaled nitric oxide, and surfactant therapy have improved outcome and reduced the need for extracorporeal membrane oxygenation (ECMO) in PPHN. Newer modalities of treatment discussed in this article include systemic and inhaled vasodilators like sildenafil, prostaglandin E1, prostacyclin, and endothelin antagonists. With prompt recognition/treatment and early referral to ECMO centers, the mortality rate for PPHN has significantly decreased. However, the risk of potential neurodevelopmental impairment warrants close follow-up after discharge for infants with PPHN.

Impact of early surfactant and inhaled nitric oxide therapies on outcomes in term/late preterm neonates with moderate hypoxic respiratory failure

OBJECTIVE

We conducted a post-hoc analysis of early inhaled nitric oxide (iNO)-randomized controlled trial data to identify associations pertinent to the management of moderate hypoxic respiratory failure in term/late preterm infants.

STUDY DESIGN

Univariate and multivariate logistic regression analyses were used to determine risk factors for the progression of respiratory failure and extracorporeal membrane oxygenation (ECMO)/death.

RESULT

Among the 299 enrolled infants, oxygenation index (OI) <20 at enrollment (odds ratio 0.52, confidence interval (CI) 0.27 to 0.97) and surfactant use before randomization (odds ratio 0.47, CI 0.24 to 0.91) were associated with decreased ECMO/death rates. Early surfactant use for respiratory distress syndrome, perinatal aspiration syndrome and pneumonia/sepsis was associated with lower risk of ECMO/death (P<0.001). Early iNO (OI 15 to 25) decreased the progression of respiratory failure to OI >30 (P=0.002) and to composite outcome of OI >30 or ECMO/death (P=0.02).

CONCLUSION

This post-hoc analysis suggests that early use of surfactant and iNO in moderate respiratory failure is associated with improved outcomes.