Association of Persistent Pulmonary Hypertension in Infants With the Timing and Type of Antidepressants In Utero

This population-based cohort study examines the risk of persistent pulmonary hypertension among newborns in Denmark after antidepressant exposure in utero.

Factors relating caesarean section to persistent pulmonary hypertension of the newborn

BACKGROUND

Several studies have clearly demonstrated a significantly higher incidence of persistent pulmonary hypertension of the newborn (PPHN) in neonates delivered by caesarean section (CS) compared to those delivered vaginally. The pathophysiological factors underlying the link between CS and PPHN are still poorly understood. In this review, we describe the mechanisms that could explain the association between CS delivery and subsequent PPHN, as well as potential preventive measures.

DATA SOURCES

A literature search was conducted by electronic scanning of databases such as PubMed and Web of Science using the key words "persistent pulmonary hypertension of the newborn", "caesarean section", "iatrogenic prematurity", "oxidative stress", "late preterm", "labor" and "vasoactive agents".

RESULTS

Iatrogenic prematurity, higher rates of late preterm delivery and lack of physiological changes of labor play an important role in the association between CS and PPHN. CS delivery also results in limited endogenous pulmonary vasodilator synthesis and lower levels of protective anti-oxidants in the neonates. In addition, CS delivery exposes infants to a higher risk of respiratory distress syndrome and its concomitant increase in endothelin-1 levels, which might indirectly lead to a higher risk of developing PPHN. We believe that neonates delivered by CS are exposed to a combination of these pathophysiological events, culminating in an endpoint of respiratory distress, hypoxia, acidosis, and delayed transition and thereby increased risks of PPHN. The use of antenatal corticosteroids prior to elective CS in late preterm deliveries, promoting accurate informedconsent process, delaying elective CS to 39 weeks of gestation or beyond and antenatal maternal anti-oxidant supplementation could potentially mitigate the effects of CS delivery and minimize CS-related PPHN.

CONCLUSIONS

The link between CS delivery and PPHN is complex. In view of the rising rates of CS worldwide, there is an urgent need to further explore the mechanisms linking CS to PPHN and experimentally test therapeutic options in order to allow effective targeted interventions.

Prevalence and treatment of persistent pulmonary hypertension in the newborn in a Mexican pediatric hospital

Persistent pulmonary hypertension of the newborn is defined as the failure of the normal circulatory transition that occurs after birth. It is a syndrome characterized by marked pulmonary hypertension that causes hypoxemia and right-to-left extra-pulmonary shunting of blood. In the treatment of persistent pulmonary hypertension of the newborn, the goal is to increase oxygen flow to the baby's organs to prevent serious health problems. Treatment may include medication, mechanical ventilation and respiratory therapy. We performed a retrospective, descriptive and transversal study to investigate the prevalence and treatment of neonatal patients with persistent pulmonary hypertension who were admitted at the Hospital del Niño DIF from 2004 to 2008. Data, collected from hospital charts, included demographic, clinical course and use of medication. A total of 38 patients were included (prevalence of 5.7%). The average age of patients was 8.4 +/- 1.4 days. The mortality rate was 42.1%. Data were collected and 45 different drugs were given to the pediatric patients. The median number of drugs/inpatient was 8.3 (1-18). The therapeutic class most prescribed was anti-infective (29.9% of all the prescriptions), followed by cardiovascular and renal drugs (26.4% of all the prescriptions) and gastrointestinal agents (14.6% of all the prescriptions). Ranitidine was the drug most commonly used, followed by ampicillin and midazolam. We found a high mortality rate and as in many studies, the therapeutic class most used were anti-infectives.

Congenital diaphragmatic hernia: current status and review of the literature

Treatment of congenital diaphragmatic hernia (CDH) challenges obstetricians, pediatric surgeons, and neonatologists. Persistent pulmonary hypertension (PPHT) associated with lung hypoplasia in CDH leads to a high mortality rate at birth. PPHT is principally due to an increased muscularization of the arterioles. Management of CDH has been greatly improved by the introduction of prenatal surgical intervention with tracheal obstruction (TO) and by more appropriate postnatal care. TO appears to accelerate fetal lung growth and to increase the number of capillary vessels and alveoli. Improvement of postnatal care over the last years is mainly due to the avoidance of lung injury by applying low peak inflation pressure during ventilation. The benefits of other drugs or technical improvements such as the use of inhaled nitric oxide or extracorporeal membrane oxygenation (ECMO) are still being debated and no single strategy is accepted worldwide. Despite intensive clinical and experimental research, the treatment of newborn with CDH remains difficult.

Risk factors for persistent pulmonary hypertension of the newborn

OBJECTIVE

Persistent pulmonary hypertension of the newborn, a clinical syndrome that results from the failure of the normal fetal-to-neonatal circulatory transition, is associated with substantial infant mortality and morbidity. We performed a case-control study to determine possible antenatal and perinatal predictors of persistent pulmonary hypertension of the newborn.

METHODS

Between 1998 and 2003, the Slone Epidemiology Center enrolled 377 mothers of infants with persistent pulmonary hypertension of the newborn and 836 mothers of matched control subjects. Within 6 months of delivery, study nurses interviewed participants regarding demographic, medical, and obstetric characteristics.

RESULTS

Factors that were independently associated with an elevated risk for persistent pulmonary hypertension of the newborn were infant male gender and black or Asian maternal race compared with white race. High prepregnancy BMI (>27 vs <20) was also associated with persistent pulmonary hypertension of the newborn, as were diabetes and asthma. Compared with infants who were delivered vaginally, the risk for persistent pulmonary hypertension of the newborn was higher for those who were born by cesarean section. Compared with infants who were born within 37 to 41 gestational weeks, the risk was higher for those who were born between 34 and 37 completed weeks and for those born beyond 41 weeks. Compared with infants within the 10th and 90th percentiles of birth weight for gestational age distribution, the risk was higher for infants above the 90th percentile.

CONCLUSIONS

Our findings suggest an increased risk for persistent pulmonary hypertension of the newborn associated with cesarean delivery; late preterm or postterm birth; being large for gestational age; and maternal black or Asian race, overweight, diabetes, and asthma. It remains unclear whether some of these factors are direct causes of persistent pulmonary hypertension of the newborn or simply share common causes with it; however, clinicians should be alert to the increased need for monitoring and intervention among pregnancies with these risk factors.

Increased incidence of idiopathic persistent pulmonary hypertension in Down syndrome neonates

Down syndrome (DS) patients have an increased risk of developing pulmonary hypertension later in life compared to age-matched controls. The goal of this study was to determine if the incidence of persistent pulmonary hypertension of the newborn (PPHN) is also higher in neonatal DS patients compared to the general population. A retrospective chart review of DS patients admitted during a 3-year period to the neonatal intensive care unit was performed. DS patients with meconium aspiration syndrome, pulmonary infections, or pulmonary space-occupying lesions were excluded. DS patients were divided into four groups based on treatment and consisted of no intervention (A), supplemental oxygen (B,) mechanical ventilation use (C), and inhaled nitric oxide administration (D). Group D was defined as having PPHN. z test of the difference between sample and known population, chi-square, t-test, and analysis of variance with Tukey adjusted post hoc test were used for analysis. p<0.05 was considered significant. A total of 58 patients met inclusion criteria. Twenty-four DS patients were in group A, 17 in group B, 10 in group C, and 7 in group D. There was no difference between the four groups for gender (males: 10, 5, 5, and 5, respectively), gestational age (36.4, 38.2, 36.4, and 36.4 weeks, respectively), weight (2.8, 3.0, 2.4, and 3.0 kg, respectively), or the presence of congenital heart defects (17, 10, 6, and 1, respectively). The estimated number of DS patients born in the state of Ohio during this period was 598; therefore, the incidence of PPHN in DS was 1.2%. The reported incidence of PPHN is 0.1%. The reported incidence of PPHN was significantly lower versus the incidence of PPHN in DS (z=2.7, p=0.007). It was concluded that DS patients have an increased incidence of PPHN compared to historical controls regardless of baseline demographics.

Elective caesarean section and respiratory morbidity in the term and near-term neonate

AIM

The aim of this review was to assess the relationship between delivery by elective caesarean section and respiratory morbidity in the term and near-term neonate.

METHODS

Searches were made in the MEDLINE database, EMBASE, Cochrane database and Web of Science to identify peer-reviewed studies in English on elective caesarean section and respiratory morbidity in the newborn. We included studies that compared elective caesarean section to vaginal or intended vaginal delivery, with clear definition of outcome measures and information about gestational age.

RESULTS

Nine eligible studies were identified. All studies found that delivery by elective caesarean section increased the risk of various respiratory morbidities in the newborn near term compared with vaginal delivery, although the findings were not statistically significant in all studies. It was inappropriate to carry out a meta-analysis with a pooled risk estimate because of a variety of methodological differences between the studies. The overall risk for respiratory morbidity, however, seemed to increase about 2 to 3 times, though some studies presented much higher risk estimates. A decreasing risk with increasing gestational age was shown in 2 studies.

CONCLUSION

Delivery by elective caesarean section was shown to increase the risk of respiratory morbidity in all studies eligible for inclusion. The magnitude of this relative risk seemed to depend on gestational age even in deliveries after 37 completed weeks of gestation.

Persistent Pulmonary Hypertension of the Newborn With Transposition of the Great Arteries

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) in patients with transposition of the great arteries (TGA) is reported to be a high-risk and often therapy-resistant condition, associated with a high mortality. However, data on its incidence and prognosis are scarce and originate mostly from the era before introduction of inhaled nitric oxide (iNO) therapy for PPHN.

METHODS

This is a retrospective study of consecutive newborns with TGA, admitted to a tertiary cardiac and neonatal intensive unit over a 10-year period. In this period, iNO therapy was available.

RESULTS

Fourteen out of 112 patients with TGA (12.5%) presented with associated PPHN. The PPHN occurred more frequently in patients with TGA and intact ventricular septum (IVS) compared with those with TGA and ventricular septal defect (13 out of 83 patients versus one out of 29 patients, respectively; p = 0.06, Fisher exact test). Of those newborns, six presented with severe PPHN, whereas eight presented with mild-to-moderate PPHN. Despite currently available treatment modalities, including iNO, four out of 14 patients died before corrective surgical procedures were considered to be an option (TGA/PPHN preoperative mortality 28.6%). These included three out of six patients (50%) with severe PPHN and one out of eight (12.5%) with mild-to-moderate PPHN.

CONCLUSIONS

The combination of TGA with PPHN is a serious and often fatal condition. It may jeopardize the usually favorable outcome of newborns with TGA. Despite the introduction of iNO therapy, the combination of TGA and PPHN remains a condition with unacceptable high mortality (in our series). Additional treatment strategies need to be investigated.

Meta-analysis of inhaled nitric oxide in premature infants: an update

INTRODUCTION

The role of inhaled nitric oxide (iNO) in the treatment of severe hypoxemic respiratory failure of term neonates has been firmly established in several randomized trials. In contrast, the use of iNO in premature newborns has remained controversial. We performed a meta-analysis of five published randomized controlled trials involving a total of 808 infants below 34 weeks of gestation.

RESULTS

The rates of major intracranial hemorrhage (ICH) were similar in both groups (42 of 208 infants receiving iNO vs 52 of 185 controls, relative risk (RR) 0.72, 95 % confidence interval (CI) 0.50-1.02) as was the mortality rate (169 of 415 receiving iNO vs 155 of 393 controls, RR 1.03, 95 % CI 0.87-1.22). Of 415 infants receiving iNO, 188 infants were diagnosed as having chronic lung disease (CLD), compared to 215 of 393 control infants. The RR in favor of iNO was 0.83, 95 % CI 0.72-0.95, p = 0.0092. Treatment failure, defined as death or CLD was significantly reduced in the iNO group (iNO: 126 of 208 infants versus control: 139 of 185, RR in favor of iNO 0.81, 95 % CI 0.70-0.93, p = 0.0025).

CONCLUSIONS

We conclude that the use of iNO may decrease the CLD and the combined endpoint CLD and mortality in preterm infants with hypoxemic respiratory failure. However, the most recent and by far largest study was terminated due to an increase in severe ICH. Therefore a cautious use of iNO in preterm infants at risk for ICH is mandatory. Further studies with appropriate neurodevelopmental follow-up need to elucidate if the reduction of CLD in very low birth weight infants is potentially associated with modifications in neurodevelopmental outcome.

Persistent pulmonary hypertension of the newborn: not a honeymoon anymore

Persistent pulmonary hypertension of the newborn is a disorder of transition to extrauterine life, in which the newly born baby cannot decrease the high pulmonary vascular resistance and low pulmonary blood flow, characteristic of the fetus, to that of a low pulmonary vascular resistance and high pulmonary blood flow necessary for postnatal survival. The syndrome primarily affects the neonate 34 weeks postmenstrual age and greater. The article will summarize the latest understanding of the pathophysiology and review innovations in management strategies that have greatly decreased mortality and morbidity since the advent of neonatal intensive care units.

Clinical characteristics and follow up of Down syndrome infants without congenital heart disease who presented with persistent pulmonary hypertension of newborn

We identified seventeen infants with Down syndrome without structural congenital heart disease who presented with persistent pulmonary hypertension in the newborn period. Respiratory distress with or without hypoxia was the presenting feature in these infants. Pulmonary hypertension resolved in the majority of the survivors. Two infants with refractory pulmonary hypertension benefited from patent ductus arteriosus ligation. Autopsies in two infants demonstrated structural lung immaturity. We suggest that infants with Down syndrome are at risk of developing persistent pulmonary hypertension even in the absence of structural heart disease and these infants should be followed up until resolution of the pulmonary hypertension.

Incidence of alveolar capillary dysplasia in severe idiopathic persistent pulmonary hypertension of the newborn

OBJECTIVE

To determine the incidence and outcome and to review the management of alveolar capillary dysplasia (ACD) among newborns with severe idiopathic persistent pulmonary hypertension (PPHN).

METHODS

A retrospective review of medical records of infants admitted to a paediatric intensive care unit from 1982 to 2000 with a diagnosis of severe PPHN, and re-examination of lung histological sections was carried out.

RESULTS

Thirteen new-born infants with pulmonary hypertension not associated with any known cause were identified. All were treated with conventional mechanical ventilation or high-frequency oscillatory ventilation with high inspired-oxygen and non-specific pulmonary vasodilators. Nine infants were also treated with inhaled nitric oxide therapy and eight with extracorporeal membrane oxygenation (ECMO). Seven infants died and six survived. At autopsies, the histological features of ACD were seen in the six who had died in the newborn period. All these had been treated with ECMO. In two of these six infants, lung biopsies had been performed showing similar features, suggesting the possibility of diagnosis during life. In the remaining infant, who died at 3 months of age, there was only marked hypertrophy of the muscle coat in the small pulmonary arteries.

CONCLUSIONS

Alveolar capillary dysplasia is probably not as rare a condition as previously suggested in sporadic case reports from literature on the subject. It should be entertained as a cause of otherwise severe idiopathic PPHN of the newborn, particularly if ECMO is required. Diagnosis during life is possible by lung biopsy. It is uncertain if survival occurs with milder forms of the condition.

Neonatal-perinatal risk factors for the development of persistent pulmonary hypertension of the newborn in preterm newborns

There is a long-held belief that preterm newborns lack sufficient arteriolar musculature to maintain a prolonged elevated pulmonary vascular resistance (PVR) after birth. Net ductal flow is thought to be minimal, with the developing pulmonary circulation incapable of significant vasoconstriction. We identified retrospectively 15 premature newborns over a 10-year period weighing < or = 1500 g and with a gestational age of < or = 30 weeks with documented persistent pulmonary hypertension of the newborn (PPHN) in the first 24 hours after birth. We matched 36 newborns of similar weight and gestation with no clinical evidence of shunting. The control group weaned to an FiO2 < or = 0.50 by 12 hours after birth. Despite similar gestational ages, the PPHN group (n = 15) had significantly higher birth weights than the control group (n = 36). The duration of ruptured membranes, maternal tobacco use, and use of antenatal steroids were significantly higher in the PPHN group. We speculate that these three factors might act in a synergistic relationship with which to accelerate pulmonary vascular smooth muscle development in premature newborns.

Child health status, neurodevelopmental outcome, and parental satisfaction in a randomized, controlled trial of nitric oxide for persistent pulmonary hypertension of the newborn

OBJECTIVE

To describe health and neurodevelopmental outcomes and parental satisfaction with hospital care among surviving intervention and control enrollees in a randomized, controlled trial of nitric oxide for persistent pulmonary hypertension of the newborn (PPHN).

METHODS

All surviving enrollees 1 to 4 years of age were eligible for follow-up. Outcomes were assessed by telephone using a trained interviewer and standardized instruments. Domains assessed included parental report of specific conditions and hospital use, rating of general health, cognitive and motor development, behavior problems, temperament, and satisfaction with the hospital stay. Fisher's exact test and the Wilcoxon rank sum test assessed differences between intervention and control infants.

RESULTS

Interviews were completed on 60 of 83 survivors (72%). Eighteen families (22%) could not be located, 2 (2%) were non-English-speaking, and 3 (4%) declined participation. No postdischarge deaths were ascertained. Among those interviewed, race, income, and education of parents of intervention and controls were comparable, as were entry oxygenation index, extracorporeal oxygenation utilization, and days of hospitalization. No differences were found in pulmonary, neurologic, cognitive, behavioral, or neurosensory outcomes; hospital readmission rates; or parental ratings of child's health. The overall neurologic handicap rate was 15%. The rate of hearing deficit was 7%. The rate of significant behavioral problems was 26%. Levels of satisfaction expressed were high for each group. No differences in parental ratings were found between the 2 groups.

CONCLUSIONS

No adverse health or neurodevelopmental outcomes have been observed among infants treated with nitric oxide for PPHN. The parents of the critically ill infants enrolled in our clinical trial welcomed their child's inclusion and all expressed satisfaction with the care that their child received while at a tertiary care hospital. Enrollment in either arm of this randomized, controlled trial did not seem to affect parental satisfaction with the hospital care that their child received.

Echocardiographic outcome of infants treated as newborns with inhaled nitric oxide for severe hypoxemic respiratory failure

OBJECTIVE

To determine the cardiovascular outcome of a group of term newborns treated with inhaled nitric oxide (iNO) for severe hypoxemic respiratory failure with associated persistent pulmonary hypertension.

STUDY DESIGN

We performed echocardiographic evaluations in 40 survivors treated for severe neonatal hypoxemic respiratory failure. Each of the 40 had at least 2 follow-up echocardiograms at 3 or 6 and 24 months. These studies were compared with echocardiograms done in infants in a normal, age-matched control group.

RESULTS

Three of 31 infants met echocardiographic criteria for pulmonary hypertension at the 3-month examination. Two of the 3 had associated structural heart disease (1 with an atrial septal defect and 1 with a ventricular septal defect). At 24 months only 1 patient had pulmonary hypertension. This infant had an atrial septal defect that was surgically closed shortly after the 24-month echocardiogram because of the pulmonary hypertension. Group comparisons of 3- and 24-month echocardiographic variables showed no differences between the study and control groups. In the 31 infants in whom serial studies were completed, expected age-related changes were demonstrated between the 3- and 24-month examinations.

CONCLUSIONS

The incidence of residual pulmonary hypertension in infants treated as newborns for severe hypoxemic respiratory failure is low. The group at highest risk is those with structural heart disease.

Persistent pulmonary hypertension of the newborn in the era before nitric oxide: practice variation and outcomes

OBJECTIVES

In the era before widespread use of inhaled nitric oxide, to determine the prevalence of persistent pulmonary hypertension (PPHN) in a multicenter cohort, demographic descriptors of the population, treatments used, the outcomes of those treatments, and variation in practice among centers.

STUDY DESIGN

A total of 385 neonates who received >/=50% inspired oxygen and/or mechanical ventilation and had documented evidence of PPHN (2D echocardiogram or preductal or postductal oxygen difference) were tracked from admission at 12 Level III neonatal intensive care units. Demographics, treatments, and outcomes were documented.

RESULTS

The prevalence of PPHN was 1.9 per 1000 live births (based on 71 558 inborns) with a wide variation observed among centers (.43-6.82 per 1000 live births). Neonates with PPHN were admitted to the Level III neonatal intensive care units at a mean of 12 hours of age (standard deviation: 19 hours). Wide variations in the use of all treatments studied were found at the centers. Hyperventilation was used in 65% overall but centers ranged from 33% to 92%, and continuous infusion of alkali was used in 75% overall, with a range of 27% to 93% of neonates. Other frequently used treatments included sedation (94%; range: 77%-100%), paralysis (73%; range: 33%-98%), and inotrope administration (84%; range: 46%-100%). Vasodilator drugs, primarily tolazoline, were used in 39% (range: 13%-81%) of neonates. Despite the wide variation in practice, there was no significant difference in mortality among centers. Mortality was 11% (range: 4%-33%). No specific therapy was clearly associated with a reduction in mortality. To determine whether the therapies were equivalent, neonates treated with hyperventilation were compared with those treated with alkali infusion. Hyperventilation reduced the risk of extracorporeal membrane oxygenation without increasing the use of oxygen at 28 days of age. In contrast, the use of alkali infusion was associated with increased use of extracorporeal membrane oxygenation (odds ratio: 5.03, compared with those treated with hyperventilation) and an increased use of oxygen at 28 days of age.

CONCLUSIONS

Hyperventilation and alkali infusion are not equivalent in their outcomes in neonates with PPHN. Randomized trials are needed to evaluate the role of these common therapies.

[The prevalence and characteristics of persistent pulmonary hypertension of the newborn. A multicenter study. The Study Group of the Società Italiana di Cardiologia Pediatrica (SICP)]

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) is a rare syndrome with a severe prognosis, in which a prompt diagnosis can be life-saving. The aim of our study was to verify its prevalence in a neonatal population, define clinical and echocardiographic criteria for the diagnosis of PPHN and discuss therapeutic choices.

METHODS

The following clinical and echocardiographic criteria for the diagnosis of PPHN were defined: 1. cyanosis and hypoxemia non-responsive to O2 therapy; 2. right to left shunt at an atrial or ductal level. All neonates fulfilling these criteria referred to the neonatal units of seven pediatric or general hospitals over a two-year period were enrolled.

RESULTS

From January 1995 to December 1996, thirty neonates with PPHN (8%) were observed. Birth was pre-term in 5 out of 30. Ten (33%) had experienced chronic and/or fetal asphyxia (FA). Death occurred in 7 (22%), four of whom with FA. Echocardiography showed tricuspid insufficiency in 18 (60%); mean pulmonary systolic pressure was 67 +/- 16 mmHg (range 41-95). In 23 surviving neonates, normalization of clinical and echocardiographic parameters occurred in 8 +/- 5 days.

THERAPY

In most neonates, vasodilators (tolazoline, prostacyclin) and/or nitric oxide were employed.

CONCLUSIONS

PPHN is confirmed to be a rare pathological condition; prognosis is severe, particularly in neonates with FA. Echocardiography is a reliable non-invasive method for a prompt diagnosis and follow-up. Subsequent studies are needed to assess therapeutic choices.

Maternal tobacco smoke exposure and persistent pulmonary hypertension of the newborn

We propose that in utero exposure to tobacco smoke products places a newborn at risk for persistent pulmonary hypertension of the newborn (PPHN). To test this hypothesis, infants with PPHN were identified. Healthy newborns of similar ethnicity were identified as a comparison group. Cord blood cotinine concentrations and maternal questionnaires were obtained. The number of women exposed to tobacco smoke in each group ascertained by questionnaire was borderline significantly different (38.7% vs. 20.5%; p = 0.080). However, more PPHN infants had detectable cotinine in their cord blood (64.5% vs. 28.2%; p = 0.002), and the median cotinine concentrations were significantly higher (5.2 ng/ml vs. 2 ng/ml; p = 0.051) than the comparison infants. Among infants delivered to nonsmoking women, more PPHN infants had detectable cotinine (50% vs. 19%; p = 0.015), and the cotinine concentrations were higher (3.5 ng/ml vs. 1.65 ng/ml; p = 0.022) than the comparison group. We conclude that active and passive smoking during pregnancy is a risk factor for PPHN. Therefore, we recommend that pregnant women cease smoking and avoid environmental tobacco smoke. Key words. cotinine, newborns, passive, persistent pulmonary hypertension, smoking, tobacco smoke pollution.

Persistent pulmonary hypertension of the newborn and smoking and aspirin and nonsteroidal antiinflammatory drug consumption during pregnancy

OBJECTIVE

Prenatal causation of persistent pulmonary hypertension of the newborn (PPHB) is suggested by a specific pattern of pulmonary vascular remodeling observed immediately after birth in some infants with fatal PPHN. The goal of this study was to determine whether PPHN is associated with fetal exposure to: (1) tobacco and marijuana smoking (ie, contributors to fetal hypoxemia), (2) consumption of aspirin and other nonsteroidal antiinflammatory drugs (ie, inhibitors of prostaglandin synthesis), and (3) cocaine use (ie, a contributor to vasospasm).

DESIGN

Case-control interview study.

SETTING

Two Harvard-affiliated newborn intensive care units.

PARTICIPANTS

Mothers of case infants who had PPHN or who met criteria for the referent group.

INTERVENTIONS

During July 1985 through April 1989, we interviewed mothers of 103 infants with PPHN and 298 control infants. Because of potential selection bias that might result from recruiting only inborn control infants even though two-thirds of cases were outborn, separate analyses compared the 103 total and 35 inborn infants with PPHN with the 298 inborn control infants. Multivariate analyses were used to adjust for potential confounding factors, including maternal education and Medicaid health insurance (ie, two markers of socioeconomic status), other antenatal factors found to be associated with PPHN (ie, maternal urinary tract infection and diabetes mellitus), and the infant's sex.

MAIN OUTCOME MEASURES

Self-reported use or consumption of tobacco, marijuana, cocaine, aspirin, and other nonsteroidal antiinflammatory drugs during pregnancy.

RESULTS

The adjusted odds ratios (and 95% confidence intervals) for maternal pregnancy exposures to the factors of principal interest among the total study population were: aspirin, 4.9 (1.6-15.3); and nonsteroidal antiinflammatory drugs, 6.2 (1.8-21.8); for the inborn group they were aspirin, 9.6 (2.4-39.0); and nonsteroidal antiinflammatory drugs, 17.5 (4.3-71.6). Although the association between tobacco smoking during pregnancy and PPHN was elevated in univariate analyses, with odds ratios (and 95% confidence intervals) of 2.0 (1.2-3.4) and 1.3 (0.6-3.3) for total and inborn populations, respectively, the relationship was not significant after adjustment for all other factors in the final logistic regression model. Acknowledged illicit drug use was too infrequent (3.2%) to evaluate.

CONCLUSION

Maternal consumption of nonsteroidal antiinflammatory drugs and aspirin during pregnancy or the reasons these drugs were ingested seem to contribute to an increased risk of PPHN.

Assisted ventilation in neonates: the Manipal experience

Case records of 68 newborns who required assisted ventilation over a 24 month period were reviewed. Fortyfour (64.7%) received intermittent mandatory ventilation, 10 (14.7%) received nasal CPAP and the remaining 14 (20.58%) received a combination of the above. Some of the indications for ventilation were infections (21), hyaline membrane disease (16), problems related to asphyxia (11), apnea of prematurity (10) and persistent pulmonary hypertension of newborn (5). The overall survival rate was 41.17%. In the CPAP group 90% (9/10) survived, while in the remaining survival was 32.7% (19/58). The best outcome was observed in persistent pulmonary hypertension of newborn (80%) followed by apnea of prematurity (70%) and hyaline membrane disease (43.75). Outcome was poor in conditions related to birth asphyxia (27.2%) and infections (19.05%). Survival rates were higher (44.4%) in babies weighing > 1500g at birth as compared to 40.9% in babies < 1500g. Babies less than 32 weeks gestation had a survival rate of 32% as compared to 46.5% in those over 32 weeks. This difference was not statistically significant. Complications were seen in 12/68 patients (17.6%). Pneumothorax was the commonest followed by sepsis, intraventricular hemorrhage and blocked endotracheal tubes. Babies with hyaline membrane disease had the highest incidence of complications. Analysis of the data with regard to the indications, outcome and complications is presented.

Respiratory disorders of the neonate

This paper presents recently published literature linking current understanding of neonatal respiratory physiology and pathophysiology to current therapy. Respiratory development is a continuum. The persistence of a fetal breathing pattern into the neonatal period may explain idiopathic neonatal apnea and the pattern of breathing seen with asphyxial apnea. Discussion with the obstetrician will focus more on prenatal diagnosis and on ensuring that prenatal corticosteroids are given. The advent of inhaled nitric oxide therapy for persistent pulmonary hypertension of the newborn offers a viable method of avoiding extracorporeal membrane oxygenation. New insights into the management of respiratory distress syndrome are derived from studies of how lung mechanics are altered by surfactant therapy. Lung injury due to capillary stress is highlighted as is attention to the way in which artificial ventilation is performed. Finally, the development of optimal guidelines for care in respiratory distress syndrome must involve consideration of multiple, interacting factors and their impact on associated conditions, especially periventricular hemorrhage.

Eicosanoids decrease with successful extracorporeal membrane oxygenation therapy in neonatal pulmonary hypertension

Elevated concentrations of eicosanoids have been reported in bronchoalveolar lavage fluid (BALF) and blood of infants with persistent pulmonary hypertension (PPHN), thereby indicating their potential role in its pathophysiology. Extracorporeal membrane oxygenation (ECMO) has improved the outcome in selected infants with PPHN. We hypothesized that ECMO, by alleviating lung injury, would be associated with decreased eicosanoid production and clinical improvement. Twenty-two newborns with PPHN treated with either ECMO or conventional means were studied. Concentrations of TxB2, 6-keto-PGF1 alpha, PGD2, PGE2, LTB4, and LTE4 were serially measured in BALF. Elevated concentrations of all eicosanoids measured were observed in all infants with PPHN at the initiation of ECMO. Eicosanoid concentrations decreased in all infants with a good clinical outcome after ECMO, but they remained elevated in those with a poor outcome. In patients with less severe PPHN, not requiring ECMO, lower concentrations of eicosanoids were observed at initiation of therapy. Eicosanoid levels increased or did not change over the course of conventional treatment. We conclude that eicosanoids are present in high concentrations in infants with PPHN. Iatrogenic factors, including oxygen and barotrauma, appear to correlate with their concentrations. Removal of these factors is associated with decreased production of mediators and clinical improvement.

Subclinical persisting pulmonary hypertension in chronic neonatal lung disease

The development of pulmonary hypertension is one of the adverse factors in the outcome of infants with chronic neonatal lung disese (CNLD). The purpose of this cross sectional study was to evaluate the prevalence and degree of pulmonary hypertension in a cohort of survivors of CNLD stable in air. Pulmonary artery pressure was assessed using its inverse correlation with the ratio of time to peak velocity and right ventricular ejection time (TPV:RVET) as measured from Doppler velocity time signals in the main pulmonary artery. A normal ratio is > or = 0.35, a possibly low ratio lies between 0.31 and 0.35, and a definitely low ratio is < 0.31. The subjects were divided into three groups. Group A comprised 58 infants with oxygen dependence and an abnormal chest radiograph at 28 days of age; group B comprised 18 infants with oxygen dependence and a normal chest radiograph at 28 days of age; and group C (controls) comprised 21 siblings without oxygen dependence by 10 days and a normal chest radiograph. There were significant differences in mean (SD) TPV:RVET ratio between group A 0.346 (0.045), group B 0.335 (0.057), and groups A + B 0.344 (0.048) when compared with group C controls 0.385 (0.034). The prevalence of a definitely low TPV:RVET ratio suggesting a raised pulmonary artery pressure was 19% in group A, 39% in group B, 24% in groups A + B, and none in group C. There were no clinical signs of pulmonary hypertension in any patient studied. Stepwise multiple linear regression failed to find significant associations with antenatal or neonatal putative risk factors. Additionally, there were no associations with childhood respiratory morbidity. These data suggest a high prevalence of subclinical pulmonary hypertension in CNLD patients. It is speculated that occult hypoxaemia may be occurring in this group of infants.

Persistent pulmonary hypertension in high-risk congenital diaphragmatic hernia patients: incidence and vasodilator therapy

Survival of congenital diaphragmatic hernia patients depends on the gravity of pulmonary hypoplasia and persistent pulmonary hypertension (PPH). Many vasoactive drugs have been used in the treatment of PPH, but often they also lower peripheral resistance, leading to a significant drop in arterial blood pressure. The incidence of PPH in 52 high-risk diaphragmatic hernia patients and the results of treatment with tolazoline and prostacyclin were evaluated in a study lasting 52 months and involving 52 patients. High-risk patients require ventilatory support within 6 hours after birth. Study parameters were alveolar-arterial oxygenation difference (AaDO2), oxygenation index (OI), and mean arterial blood pressure (MABP), measured at set times before and after administration of tolazoline or prostacyclin. Twenty-one patients had documented episodes of PPH (46%), and 18 of them died. Tolazoline did not lower AaDO2 and OI values, but MABP dropped significantly. Prostacyclin caused a significant decrease of AaDO2 and OI values without an effect on MABP. We concluded: (1) PPH presented in 46% of our patients, associated with a high mortality rate; (2) tolazoline is not an effective dilator of the pulmonary vascular bed and lowers MABP; and (3) prostacyclin is an effective pulmonary vasodilator as reflected by ventilation parameters without systemic side effects; it does not affect overall outcome but can used as a "bridge" to extracorporeal membrane oxygenation.

Early changes in the neonatal circulatory transition

To define the course of neonatal circulatory transition and to identify clinically relevant echocardiographic measurements in the diagnosis of persistent pulmonary hypertension, we prospectively studied 32 healthy term infants from 30 minutes to 24 hours after birth with color and quantitative Doppler echocardiography on the first day of life, and compared them with 33 term infants supported by mechanical ventilation for respiratory failure. Color Doppler imaging included measurements of cardiac output, left pulmonary artery flow, aortopulmonary pressure difference, ductal flow, left-to-right color-flow jet area of the ductus arteriosus, and ductal flow characteristics. In healthy infants the majority of measurable changes in cardiopulmonary hemodynamics had occurred by 8 hours after birth, although some degree of right-to-left ductal shunting was found up to 12 hours after birth. In the infants with respiratory failure, ductal flow and maximum aortopulmonary pressure difference measurements at 8, 12, and 24 hours showed a significant delay in ductal closure and a high incidence of persistent pulmonary hypertension, which correlated well with the severity of their respiratory failure. Factors such as aortopulmonary pressure difference, prolonged right-to-left shunting with decreased left pulmonary artery flow, and failure to develop a left-to-right ductal color-flow jet were found to be practical markers for assessing the course of neonatal circulatory transition in sick term infants.

Elevated immunoreactive endothelin-1 levels in newborn infants with persistent pulmonary hypertension

To study the potential role of endothelin-1, a potent endothelium-derived vasoconstrictor peptide, in the pathophysiology of persistent pulmonary hypertension of the newborn (PPHN), we measured arterial concentrations of immunoreactive endothelin-1 (irET-1) in 24 neonates with PPHN. Secondary diagnoses included meconium aspiration syndrome (13 patients), sepsis (2), congenital diaphragmatic hernia (1), asphyxia (1), pulmonary hemorrhage (1), aspiration of blood (1), and respiratory distress syndrome (1). Compared with irET-1 levels in umbilical cord blood in normal infants (15.1 +/- 4.1 pg/ml; mean +/- SEM) and in newborn infants with hyaline membrane disease who were supported by mechanical ventilation (11.8 +/- 1.2 pg/ml), infants with PPHN had markedly elevated circulating irET-1 levels (27.6 +/- 3.6 pg/ml; p < 0.01 vs cord blood, hyaline membrane disease). Infants with severe PPHN requiring extracorporeal membrane oxygenation (ECMO) therapy had higher irET-1 levels than infants with milder disease (31.0 +/- 4.7 for ECMO-treated infants vs 21.2 +/- 2.0 for non-ECMO-treated infants; p < 0.05). In patients treated without ECMO, irET-1 progressively decreased during the following 3 to 5 days, paralleling clinical improvement. In contrast, irET-1 concentrations remained elevated in infants with severe PPHN during ECMO therapy. We conclude that circulating irET-1 levels are elevated in newborn infants with PPHN, are positively correlated with disease severity, and decline with resolution of disease in patients who do not require ECMO therapy. Whether endothelin-1 contributes directly to the pathophysiology of PPHN or is simply a marker of disease activity remains speculative.

Unsuspected congenital heart disease in neonates receiving extracorporeal life support: a review of ninety-five cases from the Extracorporeal Life Support Organization Registry

The purpose of this study was to determine the frequency of patients with congenital heart disease who were given extracorporeal life support (ECLS) for respiratory failure. Underlying congenital heart disease "masked" by respiratory failure occurred in 2%. The most frequent pre-ECLS diagnosis that "masked" congenital heart disease was persistent fetal circulation. Of neonates with a pre-ECLS diagnosis of persistent fetal circulation, congenital heart disease was found in 56 (9%) of 623 patients.

National survey of diagnosis and management of persistent pulmonary hypertension of the newborn

The diagnosis and management of persistent pulmonary hypertension of the newborn remains controversial. A national survey was performed to analyze recent trends in the incidence, diagnosis, management, and survival of patients with persistent pulmonary hypertension of the neonate. Sixty-six institutions from all geographical regions responded. The overall admission incidence was 3.9% +/- 2.6%. Secondary persistent pulmonary hypertension of the neonate was more common than primary. Unexplained hypoxemia, ductal level right-to-left shunting, echocardiography, and a positive response to hyperventilation were all used frequently (in at least 79% of institutions) to diagnose persistent pulmonary hypertension of the neonate. The majority of institutions considered a positive response to hyperventilation to be determined by an increase of PaO2 by 30 mm Hg with a concomitant decrease in PaCO2 to 25 mm Hg. Approximately 70% of institutions use varying ventilator techniques (ie, with or without hyperventilation), but the majority use hyperventilation predominantly. Almost all (greater than 90%) institutions used muscle paralytic agents and pulmonary vasodilators. Tolazoline was the first choice of pulmonary vasodilator therapy. The overall survival rate of persistent pulmonary hypertension of the newborn was 77.4% +/- 13.4%. Survival rate did not differ between different geographic areas of the country. There was a trend noted for improved survival with less use of muscle paralyzing agents. Yet despite varying treatment protocols, survival rates are improving.