Oral Sildenafil Use In Neonates With Persistent Pulmonary Hypertension Of Newborn

BACKGROUND

The prevalence of PPHN has been estimated at 1.9 per 1000 live births. After the discovery of iNO's, its efficacy and benefit in PPHN is well established. Even in the best of centers equipped with iNo and ECMO the mortality is around 20%. Also, iNO is expensive and difficult to administer and monitor which makes it difficult choice in our part of the world. Furthermore About 40% of patients do not respond or have rebound pulmonary hypertension after discontinuation. Owing to these reasons, other treatment modalities like phosphodiesterase inhibitors such as Sildenafil need to be evaluated.

METHODS

We report a retrospective case series of eighteen patients with PPHN admitted in NICU and treated with oral sildenafil.

RESULTS

Three (17%) babies had mild, 5 (28%) moderate and 10 (55%) severe PPHN based on echocardiography. Sildenafil was started on all patients on a mean of 1.67 days and stopped on mean 12.6 days. Initial fio2 was 100%, which after starting sildenafil decreased gradually to 40% on mean 10 days. Average length of stay in NICU was 13 days. Twelve (67%) patients survived whereas 6 (33%) expired (Figure 2). No improvement in oxygen Index after 36 hours (p<0.05) was the independent predicting risk factor for PPHN related mortality in the expired patients.

CONCLUSIONS

Oral sildenafil can be a used in conjunction with other treatment modalities for PPHN especially in resource limited settings. However further studies regarding its comparative efficacy need to be done.

Preferential streaming of the ductus venosus toward the right atrium is associated with a worse outcome despite a higher rate of invasive procedures in human fetuses with left diaphragmatic hernia

PURPOSE

Preferential streaming of the ductus venosus (DV) toward the right atrium has been observed in fetuses with left diaphragmatic hernia (LDH). The purpose of this retrospective study was to compare survival rates to discharge between a group with preferential streaming of the DV toward the right heart and a group in which this abnormal flow pattern was not present.

MATERIALS AND METHODS

We retrospectively searched our patient records for fetuses with LDH in whom liver position, DV streaming and postnatal outcome information was available. 55 cases were found and divided into two groups: Group I fetuses exhibited abnormal DV streaming toward the right side of the heart; group II fetuses did not. Various prognostic and outcome parameters were compared.

RESULTS

62 % of group I fetuses and 88 % of group II fetuses survived to discharge (p = 0.032). Fetoscopic tracheal balloon occlusion (FETO) was performed in 66 % of group I fetuses and 23 % of group II fetuses (p = 0.003). Postnatal ECMO therapy was performed in 55 % of group I fetuses and 23 % of group II infants (p = 0.025). Moderate to severe chronic lung disease in survivors was observed in 56 % of the survivors of group I and 9 % of the survivors of group II (p = 0.002).

CONCLUSION

Preferential streaming of the DV toward the right heart in human fetuses with left-sided diaphragmatic hernia was associated with a poorer postnatal outcome despite a higher rate of invasive pre- and postnatal procedures compared to fetuses without this flow abnormality. Specifically, abnormal DV streaming was found to be an independent predictor for FETO.

Novel FOXF1 mutations in sporadic and familial cases of alveolar capillary dysplasia with misaligned pulmonary veins imply a role for its DNA binding domain

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) is a rare and lethal developmental disorder of the lung defined by a constellation of characteristic histopathological features. Nonpulmonary anomalies involving organs of gastrointestinal, cardiovascular, and genitourinary systems have been identified in approximately 80% of patients with ACD/MPV. We have collected DNA and pathological samples from more than 90 infants with ACD/MPV and their family members. Since the publication of our initial report of four point mutations and 10 deletions, we have identified an additional 38 novel nonsynonymous mutations of FOXF1 (nine nonsense, seven frameshift, one inframe deletion, 20 missense, and one no stop). This report represents an up to date list of all known FOXF1 mutations to the best of our knowledge. Majority of the cases are sporadic. We report four familial cases of which three show maternal inheritance, consistent with paternal imprinting of the gene. Twenty five mutations (60%) are located within the putative DNA-binding domain, indicating its plausible role in FOXF1 function. Five mutations map to the second exon. We identified two additional genic and eight genomic deletions upstream to FOXF1. These results corroborate and extend our previous observations and further establish involvement of FOXF1 in ACD/MPV and lung organogenesis.

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.

Correlation of echocardiographic markers and therapy in persistent pulmonary hypertension of the newborn

BACKGROUND

Persistent pulmonary hypertension of the newborn (PPHN) causes morbidity and mortality in neonates. High-frequency ventilation (HFV), inhaled nitric oxide (iNO), and extracorporeal membrane oxygenation (ECMO) are used when conventional treatment fails. This study aimed to identify echocardiographic predictors of progression to these therapies before clinical deterioration.

METHODS

Echocardiographic parameters were compared for survival and need for ECMO, HFV, iNO, and prolonged mechanical ventilation (MV, >or=10 days).

RESULTS

Of 63 neonates, 95% survived, with 14% requiring ECMO, 52% requiring HFV, 67% requiring iNO, and 35% requiring MV. The following echocardiographic indices reflecting left ventricular output were decreased in sicker infants: (1) A decreased ascending aortic velocity time integral indicated an increased likelihood of ECMO (p=0.02), iNO (p=0.01), or MV (p=0.05), (2) Shorter transverse aortic arch antegrade ejection time indicated HFV (p<0.01), iNO (p<0.01), and MV (p=0.03), (3) Absent or retrograde transverse aortic diastolic flow correlated with HFV (p=0.01, iNO (p=0.01), and MV (p<0.01). These sicker patients were more likely to have smaller left ventricular end-diastolic areas (p<0.03 for all) and right-to-left atrial shunting (ECMO, HFV, and MV). There were no differences in survival.

CONCLUSIONS

Decreased left ventricular size and output correlates with the need for advanced therapies in infants with PPHN. Early identification may allow more effective management and placement of neonates at risk.

Inhaled nitric oxide therapy during the transport of neonates with persistent pulmonary hypertension or severe hypoxic respiratory failure

Our aim was to determine whether starting inhaled nitric oxide (iNO) on critically ill neonates with severe hypoxemic respiratory failure and/or persistent pulmonary hypertension (PPH), at a referring hospital at the start of transport, decreases the need for extracorporeal membrane oxygenation (ECMO), lessens the number of hospital days and improves survival in comparison with those patients who were started on iNO only at the receiving facility. The study was a retrospective review of 94 charts of neonates that had iNO initiated by the transport team at a referring hospital or only at the tertiary neonatal intensive care unit (NICU) of the receiving hospital. Data collected included demographics, mode of transport, total number of hospital days, days on inhaled nitric oxide and ECMO use. Of the 94 patients, 88 were included. Of these, 60 were started on iNO at the referring facility (Field-iNO) and 28 were started at the receiving NICU (CHLA-iNO). All patients survived transport to the receiving NICU. Death rates and ECMO use were similar in both groups. Overall, patients who died were younger and had lower birth weights and Apgar scores. For all surviving patients who did not require ECMO, the length of total hospital stay (median days 22 versus 38, P = 0.018), and the length of the hospital stay at the receiving hospital (median days 18 versus 29, P = 0.006), were significantly shorter for the Field-iNO patients than for the CHLA-iNO patients, respectively. Earlier initiation of iNO may decrease length of hospital stay in surviving neonates with PPH not requiring ECMO.

Oral sildenafil in infants with persistent pulmonary hypertension of the newborn: a pilot randomized blinded study

BACKGROUND

Persistent pulmonary hypertension (PPHN) occurs in as many as 6.8 of 1000 live births. Mortality is approximately 10% to 20% with high-frequency ventilation, surfactant, inhaled nitric oxide, and extracorporeal membrane oxygenation but is much higher when these therapies are not available. Sildenafil is a phosphodiesterase inhibitor type 5 that selectively reduces pulmonary vascular resistance.

OBJECTIVE

Our goal was to evaluate the feasibility of using oral sildenafil and its effect on oxygenation in PPHN.

DESIGN

This study was a proof-of-concept, randomized, masked study in infants >35.5 weeks' gestation and <3 days old with severe PPHN and oxygenation index (OI) >25 admitted to the NICU (Hospital Niño Jesús, Barranquilla, Colombia). The sildenafil solution was prepared from a 50-mg tablet. The first dose (1 mg/kg) or placebo was given by orogastric tube <30 minutes after randomization and every 6 hours. Preductal saturation and blood pressure were monitored continuously. OI was calculated every 6 hours. The main outcome variable was the effect of oral sildenafil on oxygenation. Sildenafil or placebo was discontinued when OI was <20 or if there was no significant change in OI after 36 hours.

RESULTS

Six infants with an OI of >25 received placebo, and 7 received oral sildenafil at a median age of 25 hours. All infants were severely ill, on fraction of inspired oxygen 1.0, and with similar ventilatory parameters. Intragastric sildenafil and placebo were well tolerated. In the treatment group, OI improved in all infants within 6 to 30 hours, all showed a steady improvement in pulse oxygen saturation over time, and none had noticeable effect on blood pressure; 6 of 7 survived. In the placebo group, 1 of 6 infants survived.

CONCLUSIONS

Oral sildenafil was administered easily and tolerated as well as placebo and improved OI in infants with severe PPHN, which suggests that oral sildenafil may be effective in the treatment of PPHN and underscores the need for a large, controlled trial.

Bench-to-bedside review: Ventilator strategies to reduce lung injury -- lessons from pediatric and neonatal intensive care

As in the adult with acute lung injury and acute respiratory distress syndrome, the use of lung-protective ventilation has improved outcomes for neonatal lung diseases. Animal models of neonatal respiratory distress syndrome and congenital diaphragmatic hernia have provided evidence that 'gentle ventilation' with low tidal volumes and 'open-lung' strategies of using positive end-expiratory pressure or high-frequency oscillatory ventilation result in less lung injury than do the traditional modes of mechanical ventilation with high inflating pressures and volumes. Although findings of retrospective studies in infants with respiratory distress syndrome, congenital diaphragmatic hernia, and persistent pulmonary hypertension of the newborn have been similar to those of the animal studies, prospective, randomized, controlled trials have yielded conflicting results. Successful clinical trial design in these infants and in children with acute lung injury/acute respiratory distress syndrome will require an appreciation of the data supporting the modern ventilator management strategies for infants with lung disease.

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.

Doppler echocardiographic predictors of outcome in newborns with persistent pulmonary hypertension

PATIENTS

We studied retrospectively the echocardiographic features of newborns with persistent pulmonary hypertension who had been randomised to receive inhaled nitric oxide or conventional therapy. We sought to identify the predictors of extracorporeal membrane oxygenation therapy, death, and response to inhaled nitric oxide.

RESULTS

Among 85 neonates studied, an extrapulmonary right-to-left shunt through either an oval foramen and/or an arterial duct was present in 80 (94%) cases. In the 64 patients (75%) with adequate images for measurements, left ventricular ejection fraction was normal or mildly depressed in 87%, but there was a decreased index of left ventricular output, inferior to 2 l/min/m2, in 61% of the cases. Using multivariate analysis, an exclusive right-to-left ductal shunt was found to be an independent predictor of death, with odds ratio of 7.8, and 95% confidence intervals from 1.2 to 52.8, with a p value of 0.04. There was also a non-significant trend toward greater use of extracorporeal membrane oxygenation in patients with a predominant left-to-right ductal shunt, the odds ratio being 0.13, with 95% confidence intervals from 0.01 to 1.22, and a p value of 0.07. In the 40 patients randomised to receive inhaled nitric oxide, 28 had a positive response as defined by a 20% reduction in the index of oxygenation as measured from the post-ductal arterial blood gas sample. A left-to-right atrial shunt increased the risk of failing to respond to inhaled nitric oxide, with an odds ratio of 7.46, 95% confidence intervals from 1.23 to 45.1, and a p value of 0.028.

CONCLUSION

Detailed Doppler echocardiographic screening of patients with suspected persistent pulmonary hypertension of the newborn may refine the selection of groups for specific treatment, and identify risk factors.

Inhaled nitric oxide and gentle ventilation in the treatment of pulmonary hypertension of the newborn--a single-center, 5-year experience

OBJECTIVE

To evaluate the effect of inhaled nitric oxide (INO) in pulmonary hypertension of the newborn (PH) in a single center over 5 years using gentle ventilation (GV), without hyperventilation or induced alkalosis.

METHODS

Data from 229 consecutive infants with PH of varied etiology treated with INO and GV, and from 67 infants with meconium aspiration syndrome (MAS) and primary PH (PPHN) treated with GV alone were reviewed over a 5-year period (86% outborn). INO was initiated at 25 ppm when PH and severe hypoxemia persisted despite maximal optimal ventilation. Hyperventilation or systemic alkalosis were not attempted.

RESULTS

Mean duration of ventilation was 9.9 +/- 14 days (median 6.5 days). Average mean airway pressure (MAP) dropped from 17.7 +/- 4.3 cm H(2)O at the referral hospital to 13.2 +/- 2.5 cm H(2)O (p < 0.001) following admission to our unit using conventional settings and GV, before starting INO. Mean oxygenation index (OI) dropped from 46.8 +/- 24.5 to 22.7 +/- 21.4 within 24 hours of INO therapy (p < 0.001). Infants with higher baseline pH and lower baseline OI responded better to INO (p < 0.02). Overall survival was 72%. Patients with MAS and PPHN had the best response, 92% survived and there was a 46% reduction in need for extracorporeal membrane oxygenation (ECMO) compared to historical pre-INO period controls (23.9% vs. 12.8%, p < 0.01). In the infants treated with GV alone, the MAP dropped from 17.2 +/- 4.3 cm H2O at the referral hospital to 12.6+/-2.4 after GV was started in our unit.

CONCLUSIONS

We conclude that INO is an effective and well-tolerated therapy for PH in infants receiving GV.

Persistent pulmonary hypertension of the newborn: echocardiographic assessment

Twenty seven newborn infants with persistent hypoxemia in the first 3 days after birth were enrolled for hemodynamic assessment using echocardiography. Measurements included pulmonary arterial pressure (peak velocity of tricuspid regurgitation (TR), patent ductus arteriosus (PDA) flow pattern, interatrial shunting flow pattern and pulmonary flow velocity ratio (the time to peak velocity/right ventricle ejection time ratio (TPV/RVET)) and left ventricular ejection fraction. The estimated systolic pulmonary arterial pressure and the systemic arterial pressure determined via an indwelling arterial line were recorded at the time of echocardiographic examination, and pulmonary arterial pressure/systemic arterial pressure was calculated. Nineteen infants (70.4%) had a TR sufficient to estimate systolic pulmonary arterial pressure. The median value of pulmonary arterial pressure/systemic arterial pressure was 1.02 (range, 0.68 to 1.78). Twenty two infants (81.5%) had a PDA and flow patterns indicating pulmonary arterial pressure above or approaching systemic arterial pressure. All infants had a foramen ovale and flow patterns were bi-directional or pure right-to-left. TPV/RVET had a wide range of values (0.23 to 0.55), and only 44.5% of infants had high pulmonary arterial pressure as reflected by low TPV/RVET ratio. Eleven infants (40.7%) had an ejection fraction below the normal range. Results of 17 survivors were compared with 8 deceased infants (2 infants of birth weight less than 1000 gm were excluded who died of massive pulmonary hemorrhage). There were no significant differences for any parameter of pulmonary arterial pressure, but ejection fraction was significantly lower in deceased infants. This study has demonstrated that it is possible to evaluate pulmonary arterial pressure noninvasively by using echocardiography in most newborn infants with clinical evidence of persistent pulmonary hypertension of the newborn (PPHN). Ejection fraction is an echocardiographic parameter which can significantly predict mortality.

Comparison of high-frequency flow interruption ventilation and hyperventilation in persistent pulmonary hypertension of the newborn

INTRODUCTION

Because of the high mortality, potential limitations, and inherent adverse effects associated with conventional therapies, as well as extracorporeal membrane oxygenation, for persistent pulmonary hypertension of the newborn (PPHN), alternative modes of ventilatory support have been researched. There is anecdotal evidence that high-frequency flow interruption ventilation (HFFI) benefits neonates with severe air leak and lung diseases unresponsive to conventional ventilation, so we conducted a study to compare the hospital course, survival rate, and incidence of chronic lung disease of neonates with PPHN treated with hyperventilation (HV) and HFFI.

METHODS

Enrolled in the study were 36 neonates who (1) were treated with HV and a fraction of inspired oxygen of 1.0 for PPHN, (2) had arterial partial pressure of oxygen (P(aO2)) values <or= 60 mm Hg, and (3) met the inclusion criteria. Neonates were assigned to either HV or HFFI treatment and there were 18 neonates in each treatment group.

RESULTS

HFFI did not statistically increase survival (78% vs 44%, p = 0.087). Compared to the HV group, the HFFI group had: (1) fewer neonates requiring vasopressor support (7 vs 14, p = 0.042); (2) lower mean pH (7.37 vs 7.52, p < 0.001) and higher mean P(aCO2) (37.7 vs 22.1 mm Hg, p < 0.001) for neonates with P(aO2) >or= 120 mm Hg; (3) shorter mean time to P(aO2) >or= 120 mm Hg (13.5 vs 50.2 h, p = 0.001); (4) shorter mean time to reduced fraction of inspired oxygen (16 vs 84 h, p < 0.001); (5) shorter mean time to fraction of inspired oxygen 0.70 (53 vs 187 h, p < 0.001); (6) shorter mean time to extubation (8.1 vs 18.7 d, p = 0.033); (7) shorter length of hospitalization (22.7 vs 50.6 d, p = 0.025); and (8) fewer neonates with chronic lung disease (1 vs 5, p = 0.018).

CONCLUSIONS

HFFI with the ventilation strategy we describe accomplishes sustained hyperoxygenation without hypocarbia and alkalosis, and response to HFFI can predict outcomes. HFFI does not significantly reduce mortality, but it does reduce the length of mechanical ventilation, the length of hospitalization, and the incidence of chronic lung disease in neonates with PPHN. The nonrandomized design of our study precludes firm conclusions about the potential benefits of HFFI. The results may be biased by practice variations. Additional randomized controlled trials are warranted to determine the efficacy of HFFI in neonates with PPHN.

Pulmonary structural maturation and pulmonary artery remodeling after reversible fetal ovine tracheal occlusion in diaphragmatic hernia

PURPOSE

Congenital diaphragmatic hernia (CDH) is associated with thickened pulmonary arteries (PA) contributing to pulmonary hypertension. In the current study, the effects of antenatal glucocorticoids and reversible tracheal occlusion (TO) on PA structure were assessed in a hypoplastic lung model.

METHODS

A left-sided CDH was created in fetal lambs at 80 days gestation, TO at 108 days, and release of the occlusion (TR) at 129 days. All were given 1 dose of maternal glucocorticoids at 135 days. At 136 days (term, 145 days), the fetus was delivered by cesarian section. CDH (n = 7), CDH + TO (n = 6), CDH + TO + TR (n = 6), and unoperated twin controls (n = 16) were compared. Outcome measurements were (1) lung growth, represented by lung weight to body weight ratio (LW/BW), (2) lung structural maturation, which is inversely proportional to mean terminal bronchiole density (MTBD), (3) PA medial and adventitial areas (square micrometers), (4) lung capillary load, which is the ratio of vessel surface area (SA) to tissue SA ratio.

RESULTS

CDH lungs were hypoplastic with a low LW/BW and high MTBD. The small PAs (<75 microm) of CDH had an increased medial area, indicating increased muscle mass and an increased adventitial area. CDH + TO +/- TR increased LW/BW and achieved normal structural lung maturity with a low MTBD. Only CDH + TO thinned the PA medial area closer to control values. The adventitial area remained thick in CDH +/- TO +/- TR when compared with controls. All 4 groups had similar capillary load.

CONCLUSIONS

TO may be especially important for PA remodeling in the latter part of gestation, because TR 1 week before delivery prevents thinning of the small PAs in CDH. The shaping achieved by TO in terms of lung growth, structural maturity, and pulmonary artery medial area thinning may prove beneficial in lessening the severity of the associated pulmonary hypertension in CDH.

Steroids in full term infants with respiratory failure and pulmonary hypertension due to meconium aspiration syndrome

Persistent pulmonary hypertension of the newborn (PPHN) due to meconium aspiration syndrome (MAS), has a high morbidity and mortality especially in centres with limited access to extra-corporeal membrane oxygenation or nitric oxide therapy. In such a setting, we conducted a pilot study to evaluate the effect of dexamethasone on severe respiratory failure with PPHN due to MAS with a view to exploring possible justification for randomised controlled trials in similar patients. We prospectively managed a consecutive case series of 14 infants over a 3-year period with the above mentioned diagnosis, who were ventilated and with an oxygenation index >25. Dexamethasone was commenced in a dose of 0.5 mg/kg per day and given for up to a maximum of 9 days in a reducing schedule. Differences between time points were analysed using analysis of variance for repeated measures. The mean age of commencing dexamethasone was 79.9 h. There was a rapid, significant improvement (P < 0.05) in the respiratory status in 13 of these infants after commencing dexamethasone, allowing weaning from the ventilator and eventual extubation at a mean age of 8.7 days. One infant died. Two infants had infective episodes. Conclusion. Dexamethasone, if started early in infants with respiratory failure and persistent pulmonary hypertension of the newborn due to meconium aspiration syndrome may be effective in improving gas exchange, and possibly avoiding extra-corporeal membrane oxygenation. A randomised controlled trial of using dexamethasone early in similar patients and setting is warranted.

Inhaled nitric oxide reduces the need for extracorporeal membrane oxygenation in infants with persistent pulmonary hypertension of the newborn

OBJECTIVE

We previously reported improved oxygenation, but no change, in rates of extracorporeal membrane oxygenation (ECMO) use or death among infants with persistent pulmonary hypertension of the newborn who received inhaled nitric oxide (NO) with conventional ventilation, irrespective of lung disease. The goal of our study was to determine whether treatment with inhaled NO improves oxygenation and clinical outcomes in infants with persistent pulmonary hypertension of the newborn and associated lung disease who are ventilated with high-frequency oscillatory ventilation (HFOV).

DESIGN

Single-center, prospective, randomized, controlled trial.

SETTING

Newborn intensive care unit of a tertiary care teaching hospital.

PATIENTS

We studied infants with a gestational age of > or =34 wks who were receiving mechanical ventilatory support and had echocardiographic and clinical evidence of pulmonary hypertension and hypoxemia (PaO2 < or =100 mm Hg on FIO2 = 1.0), despite optimal medical management Infants with congenital heart disease, diaphragmatic hernia, or other major anomalies were excluded.

INTERVENTIONS

The treatment group received inhaled NO, whereas the control group did not. Adjunct therapies and ECMO criteria were the same in the two groups of patients. Investigators and clinicians were not masked as to treatment assignment, and no crossover of patients was permitted.

MEASUREMENTS AND MAIN RESULTS

Primary outcome variables were mortality and use of ECMO. Secondary outcomes included change in oxygenation and duration of mechanical ventilatory support and supplemental oxygen therapy. Forty-two patients were enrolled. Baseline oxygenation and clinical characteristics were similar in the two groups of patients. Infants in the inhaled NO group (n = 21) had improved measures of oxygenation at 15 mins and 1 hr after enrollment compared with infants in the control group (n = 20). Fewer infants in the inhaled NO group compared with the control group were treated with ECMO (14% vs. 55%, respectively; p = .007). Mortality did not differ with treatment assignment.

CONCLUSIONS

Among infants ventilated by HFOV, those receiving inhaled NO had a reduced need for ECMO. We speculate that HFOV enhances the effectiveness of inhaled NO treatment in infants with persistent pulmonary hypertension of the newborn and associated lung disease.

Effect of initial nitric oxide concentration on outcome in infants with persistent pulmonary hypertension of the newborn

A randomized nonblinded comparison of two treatment groups was performed to determine whether treatment of infants with persistent pulmonary hypertension of the newborn using a continuous 6-ppm dose of inhaled nitric oxide (iNO) changes the likelihood of death or utilization of extracorporeal membrane oxygenation (ECMO) when compared to infants treated with 20 ppm iNO for 4 h followed by 6 ppm. Twenty-nine infants with a gestational age >/=34 weeks and a diagnosis of persistent pulmonary hypertension of the newborn were enrolled during the 3- year study period. The relative risk (20/6 vs. 6 ppm) for treatment with ECMO was 3.11 (p = 0.02), for death it was 2.80 (p = 0.32), and for either death or ECMO it was 3.42 (p = 0. 006). There was no apparent advantage of treatment with a higher dosage of iNO at the initiation of therapy in the reduction of death or utilization of ECMO. These data suggest that a continuous lower dose of iNO results in a comparable improvement in oxygenation as a short exposure of higher dose iNO at the initiation of therapy.

Low-dose nitric oxide therapy for persistent pulmonary hypertension of the newborn. Clinical Inhaled Nitric Oxide Research Group

BACKGROUND

Inhaled nitric oxide improves gas exchange in neonates, but the efficacy of low-dose inhaled nitric oxide in reducing the need for extracorporeal membrane oxygenation has not been established.

METHODS

We conducted a clinical trial to determine whether low-dose inhaled nitric oxide would reduce the use of extracorporeal membrane oxygenation in neonates with pulmonary hypertension who were born after 34 weeks' gestation, were 4 days old or younger, required assisted ventilation, and had hypoxemic respiratory failure as defined by an oxygenation index of 25 or higher. The neonates who received nitric oxide were treated with 20 ppm for a maximum of 24 hours, followed by 5 ppm for no more than 96 hours. The primary end point of the study was the use of extracorporeal membrane oxygenation.

RESULTS

Of 248 neonates enrolled, 126 were randomly assigned to the nitric oxide group and 122 to the control group. Extracorporeal membrane oxygenation was used in 78 neonates in the control group (64 percent) and in 48 neonates in the nitric oxide group (38 percent) (P=0.001). The 30-day mortality rate in the two groups was similar (8 percent in the control group and 7 percent in the nitric oxide group). Chronic lung disease developed less often in neonates treated with nitric oxide than in those in the control group (7 percent vs. 20 percent, P=0.02). The efficacy of nitric oxide was independent of the base-line oxygenation index and the primary pulmonary diagnosis.

CONCLUSIONS

Inhaled nitric oxide reduces the extent to which extracorporeal membrane oxygenation is needed in neonates with hypoxemic respiratory failure and pulmonary hypertension.

Fetal stabilization for antenatally diagnosed diaphragmatic hernia

BACKGROUND/PURPOSE

Infants with congenital diaphragmatic hernia have pulmonary hypoplasia resulting in persistent pulmonary hypertension of neonates (PPHN), which is the main contributor to both high mortality and morbidity. The pulmonary artery bed in patients with congenital diaphragmatic hernia (CDH) is underdeveloped and is very sensitive to slight stimuli. It is, therefore, vital to avoid any factors that might increase pulmonary vascular resistance during the perinatal treatment of these patients. Recently, fetal anesthesia for perinatal stabilization in patients with CDH has been reported. However, the efficacy of this method remains controversial. The aim of this study is to analyze the benefits of fetal stabilization using fetal anesthesia in patients with CDH.

METHODS

The authors have seen 9 cases of antenatally diagnosed CDH and attempted fetal stabilization. The indication for fetal stabilization was a lung thoracic ratio of less than 0.2, without any severe associated anomalies. The protocol for fetal stabilization was (1) monitoring the fetal respiratory movement and heart beat by ultrasonography, (2) the administration of morphine (20 to 30 mg) and diazepam (5 mg) to the mother, (3) the confirmation of any interruptions in fetal movement followed by a cesarean section, (4) pancuronimum (0.5 mg) was given through the umbilical vessels, (5) intubation before clamping of the umbilical cord, and (6) high-frequency oscillatory ventilation (HFO) without bagging.

RESULTS

The lung-thratic ratio (LTR) was between 0.06 to 0.17 (average, 0.10+/-0.04). Operation was performed in 7 of 9 patients at between 2.5 and 27 hours after birth. The overall survival rate was 66.7% (6 of 9). All of the patients who underwent operation within 5 hours after birth survived.

CONCLUSIONS

Perinatal stabilization using fetal anesthesia was found to be effective in preventing PPHN and shortening the period of preoperative stabilization. It also improved the survival rate of patients with severe CDH.

[Results of extracorporeal membrane oxygenation in 100 newborns with cardiorespiratory insufficiency]

OBJECTIVE

To describe the results of treatment with extracorporeal membrane oxygenation (ECMO) in newborns with severe cardiorespiratory insufficiency.

DESIGN

Prospective, descriptive.

METHODS

For all 100 newborns treated with ECMO in 1989-1997 in the Academic Hospital Nijmegen, department of Neonatology, the Netherlands, indications for treatment, complications during treatment and mortality within 6 weeks after cessation of ECMO were registered.

RESULTS

The 100 children comprised 66 boys and 34 girls, with a mean age of 2 days (range: 1-15). Indications for ECMO treatment were: meconium aspiration syndrome: 39 with 37 survivors (95%), congenital diaphragmatic hernia: 31 with 23 survivors (74%), sepsis or pneumonia: 20 with 14 survivors (70%) and 'others' among which persistent pulmonary hypertension of the newborn: 10 with 8 survivors (80%). Eighteen children died (18%). Causes of death were rebound pulmonary hypertension (9 times), intracranial haemorrhage (4), multi-organ failure (3) and pulmonary problems (2). The most important complications during treatment were bleeding problems (29), clotting problems (20) and infections (11).

Disease-related response to inhaled nitric oxide in newborns with severe hypoxaemic respiratory failure. French Paediatric Study Group of Inhaled NO

Inhaled nitric oxide (iNO) has been shown to improve oxygenation in severe persistent pulmonary hypertension of the newborn (PPHN). However, PPHN is often associated with various lung diseases. Thus, response to iNO may depend upon the aetiology of neonatal acute respiratory failure. A total of 150 (29 preterm and 121 term) newborns with PPHN were prospectively enrolled on the basis of oxygenation index (OI) higher than 30 and 40, respectively. NO dosage was stepwise increased (10-80 ppm) during conventional mechanical or high-frequency oscillatory ventilation while monitoring the oxygenation. Effective dosages ranged from 5 to 20 ppm in the responders, whereas iNO levels were unsuccessfully increased up to 80 ppm in the nonresponders. Within 30 min of iNO therapy, OI was significantly reduced in either preterm neonates (51+/-21 vs 23+/-17, P < .0001) or term infants with idiopathic or acute respiratory distress syndrome (45+/-20 vs 20+/-17, P < .0001), 'idiopathic' PPHN (39+/-14 vs 14+/-9, P < .0001), and sepsis (55+/-25 vs 26+/-20, P < .0001) provided there was no associated refractory shock. Improvement in oxygenation was less significant and sustained (OI=41+/-16 vs 28+/-18, P < .001) in term neonates with meconium aspiration syndrome and much less (OI=58+/-25 vs 46+/-32, P < .01) in those with congenital diaphragmatic hernia. Only 21 of the 129 term newborns (16%) required extracorporeal membrane oxygenation (57% survival). Survival was significantly associated with the magnitude in the reduction in OI at 30 min of iNO therapy, a gestational age > or =34 weeks, and associated diagnosis other than congenital diaphragmatic hernia. Conclusion, iNO improves the oxygenation in most newborns with severe hypoxaemic respiratory failure including preterm neonates. However, response to iNO is disease-specific. Furthermore, iNO when combined with adequate alveolar recruitment and limited barotrauma using exogenous surfactant and HFOV may obviate the need for extracorporeal membrane oxygenation in many term infants.

A retrospective study of infants with severe persistent pulmonary hypertension (PPHN) managed without extracorporeal membrane oxygenation (ECMO)

We studied 13 consecutive infants admitted to our Neonatal Intensive Care Unit over 37 months from 1 June 1994 to 30 June 1997, who were diagnosed with severe persistent pulmonary hypertension (PPHN) meeting extracorporeal membrane oxygenation (ECMO) criteria as defined by Bartlett and/or Short. They were managed with conservative ventilation strategy, with emphasis on the use of moderate ventilatory pressures whilst avoiding paralysis. Peak inspiratory pressure (PIP) on intermittent mandatory ventilation was adjusted according to adequate chest excursion. High PIP was avoided. Two main ventilatory techniques were used: 1) low ventilatory rate < or = 40/min, PIP 20 to 30 cmH2O, inspiratory time (IT) 0.5 seconds, positive end-expiratory pressure (PEEP) 5 cmH2O, and 2) high ventilatory rate 100/min, PEEP 0 cmH2O, IT 0.3 seconds. The aim was to keep preductal PaO2 > or = 50 mmHg. We did not sought to achieve alkalotic pH or low PaCO2. When PIP requirements exceeded 30 to 35 cmH2O, the use of an alternative rescue therapy such as pulmonary vasodilator, high frequency ventilation and/or surfactant were considered. Only 1 infant died of PPHN. Low mortality due to PPHN can be achieved using this strategy. There is a need for a randomised controlled trial to compare this strategy with other alternative treatment strategies.

Inhaled nitric oxide for the early treatment of persistent pulmonary hypertension of the term newborn: a randomized, double-masked, placebo-controlled, dose-response, multicenter study. The I-NO/PPHN Study Group

OBJECTIVES

To assess the dose-related effects of inhaled nitric oxide (I-NO) as a specific adjunct to early conventional therapy for term infants with persistent pulmonary hypertension (PPHN), with regard to neonatal outcome, oxygenation, and safety.

METHODS

Randomized, placebo-controlled, double-masked, dose-response, clinical trial at 25 tertiary centers from April 1994 to June 1996. The primary endpoint was the PPHN Major Sequelae Index ([MSI], including the incidence of death, extracorporeal membrane oxygenation (ECMO), neurologic injury, or bronchopulmonary dysplasia [BPD]). Patients required a fraction of inspired oxygen [FIO2] of 1.0, a mean airway pressure >/=10 cm H2O on a conventional ventilator, and echocardiographic evidence of PPHN. Exogenous surfactant, concomitant high-frequency ventilation, and lung hypoplasia were exclusion factors. Control (0 ppm) or nitric oxide (NO) (5, 20, or 80 ppm) treatments were administered until success or failure criteria were met. Due to slowing recruitment, the trial was stopped at N = 155 (320 planned).

RESULTS

The baseline oxygenation index (OI) was 24 +/- 9 at 25 +/- 17 hours old (mean +/- SD). Efficacy results were similar among NO doses. By 30 minutes (no ventilator changes) the PaO2 for only the NO groups increased significantly from 64 +/- 39 to 109 +/- 78 Torr (pooled) and systemic arterial pressure remained unchanged. The baseline adjusted time-weighted OI was also significantly reduced in the NO groups (-5 +/- 8) for the first 24 hours of treatment. The MSI rate was 59% for the control and 50% for the NO doses (P = .36). The ECMO rate was 34% for control and 22% for the NO doses (P = .12). Elevated methemoglobin (>7%) and nitrogen dioxide (NO2) (>3 ppm) were observed only in the 80 ppm NO group, otherwise no adverse events could be attributed to I-NO, including BPD.

CONCLUSION

For term infants with PPHN, early I-NO as the sole adjunct to conventional management produced an acute and sustained improvement in oxygenation for 24 hours without short-term side effects (5 and 20 ppm doses), and the suggestion that ECMO use may be reduced.

Improved oxygenation in a randomized trial of inhaled nitric oxide for persistent pulmonary hypertension of the newborn

OBJECTIVE

To determine the effect of inhaled nitric oxide (NO) on clinical outcome in newborns with persistent pulmonary hypertension (PPHN).

DESIGN

A prospective, randomized trial of patients referred to a level 3 nursery in a single large center. Clinicians were not masked to group assignment. Crossover of patients from control to NO treatment was not permitted.

METHODS

We randomized 49 mechanically ventilated newborns, transferred to our center with clinical and echocardiographic evidence of severe PPHN (arterial oxygen tension [PaO2] <100; fractional inspired oxygen = 1) to treatment with or without NO. Patients with gestational age <34 weeks or with congenital heart disease or diaphragmatic hernia were excluded. High-frequency oscillatory ventilation was used but not allowed concomitantly with NO. Primary outcome variables were oxygenation, mortality, and use of extracorporeal membrane oxygenation (ECMO).

RESULTS

Meconium aspiration syndrome and isolated PPHN were the most common diagnoses (32/49) and were distributed equally between groups. The median age at the time of entry into the study was similar between groups, 25 hours for control patients and 18 hours for NO patients. Median baseline oxygenation index (OI) was similar in 23 control (OI = 29) and 26 NO (OI = 30) patients. Mortality (8%), use of ECMO (33%), median days on mechanical ventilation (9 days), and duration of supplemental oxygen (13 days) were not different between treatment groups. PaO2, oxygen saturation, and OI improved in the NO group compared with baseline and to control patients at 15 minutes. The median percent change in OI (-31%) in the NO group was significantly different from baseline and from the control group. The difference in oxygenation between treatment groups was still apparent 12 hours after baseline. Before cannulation for ECMO, oxygenation was better in the NO group compared with control patients. Among patients who were placed on ECMO, the median time from baseline to ECMO cannulation was 2.4 hours (range, 1 to 12 hours) among control patients and 3.3 hours (range, 2 to 68 hours) for those randomized to receive NO. There was a tendency to observe fewer adverse neurologic events (seizure and intracranial hemorrhage) in the NO group (4/26 vs 8/23). One child with alveolar capillary dysplasia confirmed by postmortem examination could not be weaned from 80 parts per million of NO and transiently developed methemoglobinemia (peak methemoglobin level = 17%). No other side effects were observed.

CONCLUSIONS

Although mortality and ECMO use were similar for both treatment groups using this study size and design, sustained improvement in oxygenation with NO and better oxygenation at initiation of ECMO may have important clinical benefits. We speculate that modification of treatment to include specific lung expansion strategies with NO treatment and recognition that early improvement of oxygenation may be sustained with NO may lead to reduced use of ECMO in NO treated patients compared with controls.

Impact of new treatments for neonatal pulmonary hypertension on extracorporeal membrane oxygenation use and outcome

OBJECTIVE

To determine the impact of new treatment modalities, including high-frequency oscillatory ventilation (HFOV) and inhaled nitric oxide (INO), on extracorporeal membrane oxygenation (ECMO) use and outcome of neonatal patients with persistent pulmonary hypertension of the newborn.

STUDY DESIGN

We reviewed the medical records of neonatal patients meeting established ECMO criteria from 1988 to 1995. Clinical data were gathered from this retrospective chart review. Comparison of ECMO experiences were made between the 1988-90 period (pre-HFOV and INO, or period 1) and the 1993-95 period (HFOV and INO fully established as treatment modalities, or period 2).

RESULTS

One hundred three patients were treated with ECMO during the 8-year study period. After HFOV and INO were introduced in 1991 and 1992 respectively, the number of patients meeting established ECMO criteria who subsequently required ECMO therapy progressively declined, from 22.3 +/- 2.3 (mean +/- SD) patients per year during period 1 to 12 patients in 1991 when HFOV was introduced, 8 patients in 1992 when INO was introduced, and 5.3 +/- 2.9 patients per year in period 2. The number of patients referred for ECMO over time did not change. Survival after ECMO dropped from 84% during period 1 to 56% in period 2. Introduction of new pre-ECMO therapies has not delayed institution of ECMO, significantly increased the length of ECMO runs, or lengthened the hospital course of ECMO survivors. A comparison of the eight infants treated with ECMO in 1992 with the 10 infants treated with INO in 1993 showed a longer hospital stay and a larger average patient bill for the patients treated with ECMO.

CONCLUSION

New treatment approaches for severe persistent pulmonary hypertension have reduced ECMO use, shortened the duration of hospitalization, and reduced costs for those infants responding to HFOV and INO. However, survival of patients requiring ECMO therapy has decreased.

Inhaled nitric oxide enhances oxygenation but not survival in infants with alveolar capillary dysplasia

A complex vascular abnormality in the lungs, termed alveolar capillary dysplasia (ACD) and misalignment of the lung vessels, has been recently recognized in some infants with persistent pulmonary hypertension. These infants die despite maximal medical support including extracorporeal membrane oxygenation (ECMO). Inhaled nitric oxide has been reported to improve oxygenation in neonates with persistent pulmonary hypertension of the newborn, and may allow some infants to avoid the need for ECMO. We identified five infants who had received inhaled nitric oxide to treat refractory hypoxemia caused by persistent pulmonary hypertension of the newborn, and who subsequently died and had autopsy confirmation of ACD. Each infant received care at a different medical center. In each patient, inhaled NO increased the arterial partial pressure of oxygen dramatically. Despite initial clinical improvement, the response to NO was not sustained in any patient. As responsiveness was lost, each infant with ACD required inhaled NO concentrations of 80 ppm or higher to sustain oxygenation. Each infant died, four after extensive periods of ECMO support. This experience demonstrates that a short-term improvement after inhalation of nitric oxide does not lead to long-term survival in ACD. Further, in three infants the diagnosis of ACD was established by lung biopsy before death. Increasing awareness of this clinical entity may allow for the avoidance of costly, invasive procedures such as ECMO until more specific therapies become available.

[Congenital diaphragmatic hernia: an analysis of the results and prognostic factors prior to the development of an ECMO program]

BACKGROUND

Some neonates with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension are not adequately oxygenated with conventional treatment. The extracorporeal membrane oxygenation (ECMO) has been successful in some of them as an alternative in their management.

PATIENTS AND METHODS

We studied the charts of 47 neonates with CDH, symptomatic within 24 hours of birth, treated in our institution during the last seven years (1987-1994). In all of them, conventional ventilation and hemodynamic support was used. In 12 patients high frequency ventilation (HFV) was used and two survived. In all patients we analyzed the following ventilatory and gasometric parameters: Oxygenation index (OI)*, ventilatory index (VI)** and postductal PCO2. In 15 neonates who did not survive, a necropsy was performed and a morphometric parameter, pulmonary index (PI)*** was studied.

RESULTS

The overall survival was 60%. VI and OI showed significant differences (p < 0.001) between survivors and non-survivors with values of 460.9 +/- 303 vs 1532 +/- 500.6, respectively for VI and 10.3 +/- 5.7 vs 46.2 +/- 37.8, respectively for IO. There were no significant differences in postductal PCO2. Mean PI in the 15 non-survivors was 0.0072 +/- 0.002 (normal > 0.015). Regression coefficients of PI with OI or VI were not significant. Neonates with VI < 1000 and OI < 40 survived. All patients with VI > 1000 and OI > 40 died. Some babies with VI > 1000 and OI < 40 (21.6%) survived.

CONCLUSIONS

In our experience, the use of HFV did not improve the prognosis of these patients, but we believe that the use of ECMO in those patients with VI > 1000, and overall, patients with VI > 1000 and OI < 40 would improve the survival rates of this congenital malformation. *QI = FiO2 x MAP/PO2 postductal x 100. (MAP = Median airway pressure). **VI = VR x MAP (VR = Ventilatory rate). ***PI = Pulmonary weight/Body weight.

Survivors of extracorporeal membrane oxygenation at 1 year of age: the relationship of primary diagnosis with health and neurodevelopmental sequelae

OBJECTIVE

Although extracorporeal membrane oxygenation (ECMO) has been responsible for the improved survival of infants with cardiorespiratory failure, its use over the last decade has raised concern as to the health of the survivors and the severity of neurodevelopmental sequelae. Though infants meeting ECMO criteria have a variety of reasons prompting the use of this therapy, most studies to date have simply reported outcome on the entire population that has survived without regard to the original nature of the child's illness. The purpose of this study was to determine the type and extent of health-related problems and neurodevelopmental sequelae in infants requiring ECMO therapy and the association of these findings with the infants' primary diagnosis.

METHODS

Eighty-two neonates required ECMO therapy between May 1990 and December 1993. The most common diagnosis prompting ECMO therapy included 26% with meconium aspiration syndrome, 34% with congenital diaphragmatic hernia (CDH), 16% with persistence of the fetal circulation, and 9% with sepsis. Information concerning the hospital course was obtained through chart review, and the infants were seen at 6 and 12 months of age for medical and neurodevelopmental follow-up. Data were analyzed using descriptive statistics and Fisher's exact test, t-tests, and analysis of variance where appropriate. Assessment of hospital course and discharge data focused on the four main diagnostic groups, whereas follow-up data were further limited to the two most frequently encountered groups (meconium aspiration syndrome and CDH).

RESULTS

Overall survival was 79%. Significant differences in survival were noted based on primary diagnostic category. Those with CDH fared the worst, with an overall survival rate of 68% and a more complicated hospital course with a longer duration of ECMO. At discharge, the CDH group demonstrated a greater incidence of bronchopulmonary dysplasia, gastroesophageal reflux, feeding dysfunction, and hypotonia. No significant differences were noted in the incidence of intraventricular hemorrhage, cerebral infarction, extra-axial fluid collection, or seizures. Hearing loss was uncommon. During the first year of life, although no differences were noted in growth rate, infants in the CDH group continued to experience a higher incidence of gastroesophageal reflux (43%) and feeding dysfunction, with 36% of this group requiring tube feedings for nourishment. Although 40% of the entire ECMO population was diagnosed with bronchopulmonary dysplasia before initial discharge, by 1 year of age, 50% of those with CDH versus 17% of those with meconium aspiration syndrome continued to be clinically symptomatic. Although the ECMO population as a whole scored in the normal range developmentally, CDH infants had significantly lower motor and slightly lower cognitive scores at 1 year of age. Despite finding abnormal muscle tone in a high percentage of the entire ECMO population at discharge, most demonstrated resolution by 1 year of age. Of the CDH infants, however, 75% continued to evidence some degree of hypotonicity, which affected acquisition and quality of gross motor skills.

CONCLUSION

Despite the impact that ECMO has had on the survival of infants with severe respiratory failure, the efficacy of ECMO cannot be assessed accurately without an analysis of the extent and morbidity in the surviving population. Most centers are reporting relatively low morbidity for the entire ECMO population. However, upon separating this population into primary diagnostic categories, we found that the CDH population encountered a greater number of neurodevelopmental, respiratory, and feeding abnormalities during the first year of life. The reasons for these differences are unclear but may be related to the severity of the primary illness itself or the variables associated with prolonged ECMO therapy. Stratifying outcome by primary diagnosis gives the health care provider more information to improve

Orthotopic transplantation for total anomalous pulmonary venous connection associated with complex congenital heart disease

BACKGROUND

When total anomalous pulmonary venous connection is associated with other complex cardiac malformations, early and late postsurgical morbidity and mortality are excessive.

METHODS

In an attempt to modify this outcome, twelve children (4 days to 6.8 years of age) with total anomalous pulmonary venous connection and various congenital cardiac defects were treated with orthotopic heart transplantation. Associated cardiac diagnoses included the following: hypoplastic left heart syndrome (n = 2), unbalanced atrioventricular canal with pulmonary atresia (n = 2), and single ventricle with severe pulmonary stenosis (n = 3) or atresia (n = 5). Two patients had situs inversus, and two had dextrocardia with situs ambiguous. Eight patients had asplenia and one had polysplenia. Palliative pretransplantation procedures in five patients included the following: systemic to pulmonary artery shunt (n = 5), atrioventricular valve annuloplasty (n = 1) and classical Glenn shunt (n = 1). The donor left atrium was anastomosed directly to a common pulmonary venous pool in nine patients; whereas three children required complex reconstruction to baffle the pulmonary venous flow to the donor left atrium.

RESULTS

There was one operative death related to an oversized heart and vena caval thrombosis. Follow-up ranged from 16 months to 4.5 years (average 3 years). In two patients (18%) pulmonary venous obstruction developed 3 and 4 months after transplantation. Reoperation to relieve the obstruction was successful in one patient. The second patient underwent three such reoperations and died of sepsis 10 months after orthotopic heart transplantation.

CONCLUSION

Orthotopic transplantation is a viable option for children with complex total anomalous pulmonary venous connection that precludes a biventricular repair. Transplantation may improve the dismal prognosis of those children, but it does not eliminate the potential for late pulmonary venous obstruction.

Robust Bayesian methods for monitoring clinical trials

Bayesian methods for the analysis of clinical trials data have received increasing attention recently as they offer an approach for dealing with difficult problems that arise in practice. A major criticism of the Bayesian approach, however, has focused on the need to specify a single, often subjective, prior distribution for the parameters of interest. In an attempt to address this criticism, we describe methods for assessing the robustness of the posterior distribution to the specification of the prior. The robust Bayesian approach to data analysis replaces the prior distribution with a class of prior distributions and investigates how the inferences might change as the prior varies over this class. The purpose of this paper is to illustrate the application of robust Bayesian methods to the analysis of clinical trials data. Using two examples of clinical trials taken from the literature, we illustrate how to use these methods to help a data monitoring committee decide whether or not to stop a trial early.

The effect of on-site extracorporeal membrane oxygenation on the therapy choice and outcomes of neonates with persistent pulmonary hypertension

The effect of on-site extracorporeal membrane oxygenation (OS-ECMO) and selection criteria on the utilization rate of this technology is unknown. We retrospectively studied 55 neonates who were admitted to Arkansas Children's Hospital from 1985 to 1993. We compared the ECMO utilization, mortality, and morbidity rates for outborn neonates with moderate and severe persistent pulmonary hypertension (PPHN) before and after the establishment of an ECMO program with guidelines for its use at our institution. The rate of ECMO use was three times higher and the mortality rate was 13 times lower in the period after OS-ECMO compared with the period when ECMO was available only at other institutions. No differences were observed in the morbidity rates between the two periods. Physician decisions to initiate ECMO involved more than guidelines, since 37% of the increased ECMO use was not associated with use of the guidelines. Possible reasons for noncompliance with the guidelines are discussed. Neonates who had received medical therapy only and who had an oxygenation index > or = 30 and < 40 had no mortality. Our findings suggest that the need for ECMO in this group of neonates is low.

Persistent pulmonary hypertension of the newborn infant. Comparison of conventional versus extracorporeal membrane oxygenation in neonates fulfilling Bartlett's criteria

Persistent pulmonary hypertension of the newborn (PPHN) is a challenge for the neonatologist and a common indication for treatment with extracorporeal membrane oxygenation (ECMO) when medical management fails. We observed 132 neonates born between January 1985 and December 1988 with the diagnosis of persistent pulmonary hypertension of the newborn: 73 (55%) met the Bartlett criteria for treatment with ECMO with 80% predicted mortality; 21 (29%) deteriorated despite conventional medical treatment, were thought to be dying, and were sent for ECMO. Among the 52 patients who were medically treated 40 (77%) survived, a marked difference compared with a predicted 20% survival. All ECMO-treated neonates survived. Although conventionally treated infants showed a trend toward less dependence on supplemental oxygen at > 28 days of life, this study failed to detect a significant difference between those two groups. We conclude that mortality was lower for ECMO-treated infants than for those who were medically treated (0 of 21 vs 12 of 52, p < 0.05); mortality for infants with persistent pulmonary hypertension of the newborn who met Bartlett's criteria and were medically treated was lower than published data; and there was no significant difference in oxygen dependence at > 28 days between the survivors who received ECMO and those who received medical therapy.

High frequency oscillatory ventilation and extracorporeal membrane oxygenation in severe persistent pulmonary hypertension of the newborn

We report on 50 term and near-term neonates (birth weight greater than 1800 g, gestational age greater than 33 weeks) with severe persistent pulmonary hypertension of the newborn (PPHN), referred to us from January 1987 to July 1991 after failure of maximum conventional treatment. All infants had paO2 less than 45 mm Hg when ventilated with peak inspiratory pressure greater than 38 cm H2O and FiO2 = 1.0, hence meeting entry criteria for extracorporeal membrane oxygenation (ECMO). High frequency oscillatory ventilation (HFOV) was tried in all patients. If sufficient oxygenation could not be achieved (paO2 less than 40 mm Hg for at least 2 h), ECMO therapy was begun, which was the case in 25 children. Neonates responding to HFOV (n = 25) were of a slightly younger gestational age (37.0 weeks vs 38.8 weeks, P less than 0.05), had higher Apgar scores and were less hypoxaemic before HFOV (paO2 36.6 mm Hg vs 28.8 mm Hg, P less than 0.01); during HFOV there was a significant rise in paO2 (greater than 150 mm Hg; P less than 0.001) and a fall in pCO2 to 21.6 mm Hg (P less than 0.001). Due to air leaks, which was the main complication of HFOV (52%), ECMO therapy had to be begun in two additional infants after an initial positive effect. HFOV tended to be successful in cases of primary PPHN, meconium aspiration and sepsis, but not in infants with lung hypoplasia as a result of diaphragmatic hernia or other reasons. Success or failure of HFOV could not be reliably predicted by any parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival of infants with persistent pulmonary hypertension without extracorporeal membrane oxygenation

A retrospective evaluation was performed of the survival after conservative therapy of infants with persistent pulmonary hypertension who met the published criteria of Bartlett et al (Pediatrics. 1985;76:479-487) or Short et al (Clinics in Perinatology. 1987;14:737-748) for extracorporeal membrane oxygenation (ECMO) therapy. An 80% to 90% mortality rate can be predicted with these criteria, which are based on historical data, if ECMO is not used. The records of infants with the diagnosis of persistent pulmonary hypertension, weighing greater than 2 kg at birth and who were treated during two time periods, January 1980 to December 1981 [23 patients] and January 1986 to December 1988 [17 patients], were reviewed. During the earlier period, hyperventilation was the mainstay of our therapy, whereas during the later period, a more conservative approach (avoidance of hyperventilation) was adopted. In 1980 to 1981, 1 of the 6 patients (17%) who were eligible for ECMO by criteria of Bartlett et al survived, which is consistent with the published data. However, in 1986 to 1988, 9 of 10 ECMO-eligible patients (90%) survived (P less than .02). The corresponding survival figures using the alveolar-arterial oxygen difference criteria of Short et al were 0 of 5 survivors (0%) in 1980 to 1981 and 8 of 9 (89%) in 1986 to 1988 (P less than .006). These data indicate that approximately 90% of patients who are candidates for ECMO now survive in our institution without the use of that therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Historical controls for extracorporeal membrane oxygenation in neonates

A retrospective review of all patients cared for who met Loe's criteria for extracorporeal membrane oxygenation (ECMO) was conducted covering the 3-yr period 1983 through 1985. There were five out of 3,726 admissions who met criteria for ECMO (three of 127 outborn admissions). All infants were greater than 2 kg birth weight and met criteria based on alveolar-arterial oxygen pressure difference (P[A-a]O2), barotrauma criteria, or both P(A-a)O2 and barotrauma criteria. All infants had persistent pulmonary hypertension. Two patients also had hyaline membrane disease and one also had asphyxia and meconium aspiration. All patients were treated with conventional therapy and all survived. There were no patients who met criteria for ECMO and died and there were no patients referred for ECMO during this period. Published criteria for ECMO estimate a control group mortality rate of 80% to 94%. Mortality for this series was 0%. (Ninety-five percent confidence interval for mortality in a group of five survivors is 0% to 45%.) Controlled trials of ECMO were not done initially because it was considered unethical. This series shows that historical mortality rates are no longer valid and that controlled trials must be done.

High-frequency jet ventilation in neonatal pulmonary hypertension

To determine if high-frequency jet ventilation is beneficial in neonates with persistent pulmonary hypertension, we compared the ventilator settings, blood gas concentrations, and outcome of infants who met established criteria for a high predictive mortality. During a six-year period, 14 neonates who had severe respiratory failure and hypoxemia while receiving conventional ventilation were treated with high-frequency jet ventilation. Twenty-three comparable infants meeting the same criteria were treated exclusively with conventional ventilation. After initiation of high-frequency jet ventilation there was a significant reduction in mean airway pressure and partial pressure of arterial carbon dioxide (PaCO2). In contrast, neonates treated exclusively with conventional ventilation continued to have higher airway pressures and PaCO2. However, there was no difference in the alveolar-to-arterial oxygen gradient, air leakage, incidence of bronchopulmonary dysplasia, or duration of assisted ventilation or oxygen supplementation. Furthermore, mortality was comparable in both groups of infants. These preliminary observations suggest that high-frequency jet ventilation can reduce airway pressure and PaCO2 in neonates with persistent pulmonary hypertension but does not appear to improve outcome.

Extracorporeal membrane oxygenation in the newborn and beyond

Extracorporeal membrane oxygenation (ECMO) has gained notoriety recently as a treatment of last resort for neonates at term or near term who suffer from pulmonary failure. Because of serious inherent risks, the procedure is at present reserved for infants with reversible pulmonary disease who have failed conventional or high-frequency ventilation and who meet the prognostic criterion of 80 percent mortality.

Outcome of persistent pulmonary hypertension in relation to severity of presentation

Since the initial description of persistent pulmonary hypertension of the newborn (PPHN), the management of these infants has been controversial. A variety of therapeutic modalities, such as extracorporeal membrane oxygenation, have been utilized. Early recognition of a group of patients with PPHN who might require aggressive therapy would be clinically useful. Highest alveolar-arterial oxygen gradient at or near diagnosis was evaluated retrospectively in 53 patients with PPHN in relation to survival, aggressiveness of management, and frequency of pulmonary complications (air leak and broncho-pulmonary dysplasia). Highest alveolar-arterial oxygen gradient was a good early predictor of nonsurvival and was significantly higher in nonsurvivors compared with survivors (mean [+/- SD], 618 +/- 23 mm Hg vs 521 +/- 128 mm Hg). Values of 600 mm Hg or greater were more frequent in the nonsurvivors compared with the survivors (92% vs 37%). Air leak also proved to be a good predictor of nonsurvival.

Predicting survival in infants with persistent pulmonary hypertension of the newborn

Since persistent pulmonary hypertension of the newborn (PPHN) often occurs as a life-threatening illness, it would be advantageous to identify the highest-risk infants within the first 24 hours of life so that transfer to centers with extracorporeal membrane oxygenation (ECMO) or high-frequency ventilation can be facilitated. Fifty-three infants with PPHN were evaluated retrospectively. A multivariate discriminant analysis of risk factors determined that lowest pH, critical PaCO2, highest inspiratory pressure (PI), maximum ventilator rate, and 5-minute Apgar score were significantly different between the 35 survivors (66%) and the 18 infants (34%) who had died when examined within the first 24 hours of life. A clinical scoring system was designed based on these five criteria, which predicted outcome accurately in 93% of infants. A logistic regression analysis was performed as a check on these results and found that lowest pH, critical PaCO2, and PI predicted outcome with great accuracy. These results suggest that the use of these scoring systems within the first 24 hours of age may help predict outcome in infants with PPHN.

Criteria for extracorporeal membrane oxygenation in a population of infants with persistent pulmonary hypertension of the newborn

Extracorporeal membrane oxygenation (ECMO) has been available since 1975 as a therapy of last resort to provide adequate oxygenation for term infants with acute lung disorders that do not respond to maximal medical therapy. Virtually all term infants with serious lung disease have persistent pulmonary hypertension of the newborn (PPHN) characterized by significant right-to-left shunting of blood and severe diffusion defects manifested as increased alveolar-arterial oxygen gradients (AaDO2). Criteria for initiation of ECMO therapy have been developed in several institutions but at the present time there are no universal criteria applicable to all infants with PPHN. We have attempted to establish entry criteria that may be used for different populations of infants with PPHN. Based on a retrospective review of 30 infants with PPHN in our institution, we have defined standards of maximal medical therapy. An alveolar-arterial oxygen difference (AaDO2) of greater than or equal to 610 for 8 hours has been shown to be associated with 79% mortality in this population. This AaDO2/time interval is established as a major criterion for institution of extracorporeal membrane oxygenation.

Correction of congenital diaphragmatic hernia in utero. IV. An early gestational fetal lamb model for pulmonary vascular morphometric analysis

Infants born with congenital diaphragmatic hernia (CDH) often have specific pathologic abnormalities of the pulmonary microcirculation that result in high pulmonary vascular resistance and extrapulmonary right-to-left shunting after birth. In an attempt to make an animal model with similar vascular changes, we created CDH in fetal lambs at 60 to 63 days gestation, repaired some at 100 to 113 days gestation, and subsequently performed morphometric analysis of the pulmonary vasculature. Creation of CDH at this early gestational age resulted in a high fetal mortality rate. In the unrepaired CDH lambs, the pulmonary vascular abnormalities were more severe in the left lung. Similar to human CDH, diaphragmatic hernia in the fetal lamb resulted in a decrease in the total size of the pulmonary vascular bed, a decrease in the number of vessels per unit area lung, and increased muscularization of the arterial tree. Fetal surgical repair of CDH restored the pulmonary arterial bed towards normal.

Management of infants with severe respiratory failure and persistence of the fetal circulation, without hyperventilation

The successful management of 15 infants suffering from persistence of fetal pulmonary circulation and in severe respiratory failure is presented. The treatment regimen focused on minimizing barotrauma. Infants were intubated nasotracheally and ventilated with intermittent mandatory ventilation. Peak inspiratory pressures were determined by the clinical assessment of chest excursion. Ventilator settings and fractional inspiratory oxygen (FiO2) were selected to maintain a PaO2 between 50 and 70 mm Hg; PaCO2 was not a controlling parameter and was allowed to increase as high as 60 mm Hg. Hyperventilation and muscle relaxants were not used. High ventilator rate was used in ten infants who required high inspiratory pressure to maintain chest excursion, with a favorable response in five. Tolazoline was given to 14 infants of whom ten showed an improvement in oxygenation; dopamine was given to three infants who were oliguric. All infants survived, and only one infant developed chronic lung disease which was defined by the infant's need for supplemental oxygen beyond 30 days of life.