Ligation of the patent ductus arteriosus in premature infants: report of 45 cases

Pharmacotherapy in Bronchopulmonary Dysplasia: What Is the Evidence?

Bronchopulmonary Dysplasia (BPD) is a multifactorial disease affecting over 35% of extremely preterm infants born each year. Despite the advances made in understanding the pathogenesis of this disease over the last five decades, BPD remains one of the major causes of morbidity and mortality in this population, and the incidence of the disease increases with decreasing gestational age. As inflammation is one of the key drivers in the pathogenesis, it has been targeted by majority of pharmacological and non-pharmacological methods to prevent BPD. Most extremely premature infants receive a myriad of medications during their stay in the neonatal intensive care unit in an effort to prevent or manage BPD, with corticosteroids, caffeine, and diuretics being the most commonly used medications. However, there is no consensus regarding their use and benefits in this population. This review summarizes the available literature regarding these medications and aims to provide neonatologists and neonatal providers with evidence-based recommendations.

Respiratory Trajectory after Invasive Interventions for Patent Ductus Arteriosus of Preterm Infants

Invasive interventions have been conducted in preterm infants with significant patent ductus arteriosus (PDA) when medical treatment has failed, and methods of invasive intervention have been reported. Surgical ligation via lateral thoracotomy has been a well-established procedure for decades. Recently, transcatheter occlusion has been safely and feasibly applied to the premature population. However, little research has been conducted on the benefits of transcatheter occlusion in very-low-birth-weight (VLBW) infants compared to surgical ligation. This study compared transcatheter and surgical techniques in VLBW infants in terms of short-term respiratory outcomes. The medical records of 401 VLBW infants admitted to a tertiary hospital between September 2014 and January 2019 were retrospectively reviewed. Patients who were diagnosed with a congenital anomaly, a chromosomal anomaly, or congenital heart disease, except for an inter-atrial shunt, were excluded. The perinatal conditions, neonatal morbidities, periprocedural vital signs, and respiratory support trajectories were compared between the transcatheter-treated and surgically ligated group. A total of 31 eligible VLBW infants received invasive intervention: 14 were treated with transcatheter occlusion (Group A), and 17 infants were treated with surgical ligation (Group B). Respiratory outcomes were not statistically significant between the two groups, despite Group A showing a trend toward early improvement in post-intervention respiratory trajectory. In this small case study, a different trend in post-intervention respiratory trajectories was observed. Future research with larger case numbers should be conducted to address our preliminary observations in more detail.

PDA ligation and health outcomes: a meta-analysis

BACKGROUND AND OBJECTIVE

Patent ductus arteriosus (PDA) ligation has been variably associated with neonatal morbidities and neurodevelopmental impairment (NDI). The objective was to systematically review and meta-analyze the impact of PDA ligation in preterm infants at <32 weeks' gestation on the risk of mortality, severe neonatal morbidities, and NDI in early childhood.

METHODS

Medline, Embase, Cochrane Central Register of Controlled Trials, Education Resources Information Centre (ERIC), Cumulative Index to Nursing and Allied Health (CINAHL), PsycINFO, and the Dissertation database were searched (1947 through August 2013). Risk of bias was assessed by using the Newcastle-Ottawa Scale and the Cochrane Risk of Bias tool. Meta-analyses were performed by using a random-effects model. Unadjusted and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were pooled when appropriate.

RESULTS

Thirty-nine cohort studies and 1 randomized controlled trial were included. Nearly all cohort studies had at least moderate risk of bias mainly due to failure to adjust for survival bias and important postnatal preligation confounders such as ventilator dependence, intraventricular hemorrhage, and sepsis. Compared with medical treatment, surgical ligation was associated with increases in NDI (aOR: 1.54; 95% CI: 1.01-2.33), chronic lung disease (aOR: 2.51; 95% CI: 1.98-3.18), and severe retinopathy of prematurity (aOR: 2.23; 95% CI: 1.62-3.08) but with a reduction in mortality (aOR: 0.54; 95% CI: 0.38-0.77). There was no difference in the composite outcome of death or NDI in early childhood (aOR: 0.95; 95% CI: 0.58-1.57).

CONCLUSIONS

Surgical ligation of PDA is associated with reduced mortality, but surviving infants are at increased risk of NDI. However, there is a lack of studies addressing survival bias and confounding by indication.

Inflammatory changes in the lungs of premature infants with symptomaticpatent ductus arteriosus

BACKGROUND

The aim of the study was to observe the inflammatory changes during the therapy for symptomatic patent ductus arteriosus (sPDA).

METHODS

We investigated biochemically the sample of the tracheobroncheal aspirates (TA) from 11 intubated premature infants. Three i.v. doses of indomethacin (0.2 mg/kg)were administered with 24-h intervals. The samples were divided into two groups, the effective occasions (n = 10)and non-effective occasions (n = 6). The amounts of myeloperoxidase (MPO), soluble L-selectin (sL-selectin)in TA, and the polymorphonuclear leukocytes (PMN) of peripheral blood stream and TA were analyzed before and after treatment ofsPDA with indomethacin.

RESULTS

In effective occasions, there were significant decreases of peripheral PMN and MPO and PMN in TA. However, this group had a significant increase of sL-selectin. In non-effective occasions, five out of six samples had decreases of MPO and PMNin TA, but not significantly. In contrast, there was a significant decrease of sL-selectin.

CONCLUSION

These data suggested that anti-inflammatory change after closure of sPDA may be caused by not only indomethacin itself, but also ductal closure itself. However, further study is necessary to clarify the relationship between the closure of the ductus itself and anti-inflammatory action in the lung.

Biochemical, clinical, and morphologic studies on lungs of infants with bronchopulmonary dysplasia

We correlated clinical, biochemical, and morphologic findings in the lungs of 48 infants dying of either bronchopulmonary dysplasia (BPD) or hyaline membrane disease (HMD) to obtain a better idea of the disease process. The infants ranged from 24 weeks of gestation to 1 1/2 postnatal years. The lungs of BPD and HMD infants had higher contents of DNA, alkalisoluble protein, hydroxyproline, and desmosine, as well as increased concentrations of DNA, hydroxyproline, and desmosine when compared with the lungs of 72 control infants. BPD was classified histologically into 4 groups: Group I was a phase of acute lung injury, Group II the proliferative phase; Group III the phase of early repair, and Group IV the phase of late repair. We saw a significant increase in hydroxyproline concentration in Groups II and III. The ratio of type I/III collagen decreased in BPD Groups II to IV. Desmosine was significantly higher only in Group III than in controls. When the pathological classification was related to biochemical and clinical features of BPD, the classification showed dependence on the number of days the infant survived postnatally and not on the gestational age of the infant. The number of days on assisted ventilation was a slightly better predictor of the disease classification than days on > 60% oxygen. A statistical model correctly predicted the pathologic classification 83% of the time.

Prophylactic indomethacin therapy in the first twenty-four hours of life for the prevention of patent ductus arteriosus in preterm infants treated prophylactically with surfactant in the delivery room

OBJECTIVE

To determine whether a course of low-dose indomethacin therapy, when initiated within 24 hours of birth, would decrease ductal shunting in premature infants who received prophylactic surfactant in the delivery room.

DESIGN

Ninety infants, with birth weights of 600 to 1250 gm, were entered into a prospective, randomized, controlled trial to receive either indomethacin, 0.1 mg/kg per dose, or placebo less than 24 hours and again every 24 hours for six doses. Echocardiography was performed on day 1 before treatment and on day 7, 24 hours after treatment. A hemodynamically significant patent ductus arteriosus (PDA) was confirmed with an out-of-study echocardiogram, and the nonresponders were treated with standard indomethacin or ligation.

RESULTS

Forty-three infants received indomethacin (birth weight, 915 +/- 209 gm; gestational age, 26.4 +/- 1.6 weeks; 25 boys), and 47 received placebo (birth weight, 879 +/- 202 gm; gestational age, 26.4 +/- 1.8 weeks; 22 boys) (P = not significant). Of 90 infants, 77 (86%) had a PDA by echocardiogram on the first day of life before study treatment; 84% of these PDAs were moderate or large in size in the indomethacin-treated group compared with 93% in the placebo group. Nine of forty indomethacin-treated infants (21%) were study-dose nonresponders compared with 22 (47%) of 47 placebo-treated infants (p < 0.018). There were no significant differences between both groups in any of the long-term outcome variables, including intraventricular hemorrhage, duration of oxygen therapy, endotracheal intubation, duration of stay in neonatal intensive care unit, time to regain birth weight or reach full caloric intake, incidence of bronchopulmonary dysplasia, and survival. No significant differences were noted in the incidence of oliguria, elevated plasma creatinine concentration, thrombocytopenia, pulmonary hemorrhage, or necrotizing enterocolitis.

CONCLUSION

The prophylactic use of low doses of indomethacin, when initiated in the first 24 hours of life in low birth weight infants who receive prophylactic surfactant in the delivery room, decreases the incidence of left-to-right shunting at the level of the ductus arteriosus.

Increased platelet activating factor in the tracheal aspirates from neonates with patent ductus arteriosus

We investigated platelet-activating factor (PAF) in the tracheal aspirate from 3 intubated low birth weight infants with symptomatic patent ductus arteriosus (PDA). PAF increased with the onset of symptomatic PDA and decreased to the control range soon after the ductal closure. The concentration of PAF in 26 samples taken during symptomatic PDA (median 16 pg/micrograms lipid phosphorus, range 1.4-1,200 pg/micrograms lipid phosphorus) was significantly higher than that of 31 samples from the same three patients during the periods without symptomatic PDA (median 1.9 pg/micrograms lipid phosphorus, range 0-12 pg/micrograms lipid phosphorus; P < 0.001). All 3 infants later developed chronic lung disease. These results suggest that large shunting PDA provokes PAF release to the air way of the neonate and that PAF might play a role in chronic lung disease developing after symptomatic PDA.

Rate of bronchopulmonary dysplasia as a function of neonatal intensive care practices

Some differences among neonatal intensive care units (NICUs) in incidence of bronchopulmonary dysplasia may reflect variations in medical care practices. After adjusting for differences in the inherent risk of bronchopulmonary dysplasia among 223 infants of less than 1751 gm birth weight who were admitted to three Harvard-affiliated NICUs, we used multivariate analysis to explore the extent to which medical care practices during the first days of life varied with the rate of bronchopulmonary dysplasia. In our analyses, variables were grouped by three major hypotheses: oxygen toxicity, barotrauma, and fluid overload. The NICU designated 1 (the one with the highest rate of bronchopulmonary dysplasia) used much higher than expected colloidal volumes during the first 4 days of life; in contrast, in the NICU designated 3 (the one with the lowest rate of bronchopulmonary dysplasia), infants consistently received lower than expected amounts of colloidal solution. Signs of patent ductus arteriosus were also much more frequent than expected during this time at NICU 1; rates were much lower than predicted at NICU 2 and were near predicted values at NICU 3. Maximum inspired oxygen fraction during the first 4 days varied significantly in a direction inconsistent with the oxygen toxicity hypothesis. Maximum arterial oxygen tension was significantly less than expected at the hospital with the lowest rate of bronchopulmonary dysplasia (NICU 3). None of six medical care practices indicating potential for barotrauma varied with NICU expect for positive end-expiratory pressure, which varied in a direction suggesting a protective effect against bronchopulmonary dysplasia. These findings agree best with the hypothesis that differences in hydration during the first days of life account for some of the difference among NICUs in bronchopulmonary dysplasia occurrence.

Indication and results of thoracic surgical procedures in premature infants

This analysis concerns three groups of malformations: Congenital diaphragmatic hernia, patent ductus arteriosus, and oesophageal atresia. We registered a total mortality rate for all congenital diaphragmatic hernias and defects of 28.5%; the rate in full-term neonates was 27.6% and in premature infants 33.6%. Of 65 infants with a patent ductus arteriosus and a birth weight less than 1500 g, 14 died (21.5%). In most cases death was caused by sepsis. Among the 159 patients with oesophageal atresia who were treated in our hospital, 58 were premature infants. During the last 20 years, the total mortality rate among our patients was 28.9%. We had a mortality rate of 44.8% in premature infants and of 19.8% in full-term neonates. An analysis of the last 10 years showed a survival rate of 97% in healthy infants (group A in Waterston's classification). In group C, the most disadvantageous group (premature infants, severe anomalies), the rate was 61%.

Hydration during the first days of life and the risk of bronchopulmonary dysplasia in low birth weight infants

We conducted a case-control study of antecedents of bronchopulmonary dysplasia (BPD) in 223 infants enrolled in a prospective, randomized clinical trial of phenobarbital prophylaxis for intracranial hemorrhage. The trial took place at three Boston neonatal intensive care units between June 1981 and April 1984. The 76 babies with BPD had radiographic evidence of the condition and required oxygen therapy for 28 days or more. All 147 control babies survived until day 28 of life without meeting either of these criteria for BPD. Compared with control infants, those with BPD received greater quantities of total, crystalloid, and colloid fluids per kilogram per day in the first 4 days of life. In addition, infants with BPD generally had a net weight gain in the first 4 days of life in contrast to the normal pattern of weight loss seen in control infants. Finally, the infants with BPD were more likely to be given a clinical diagnosis of patent ductus arteriosus and to have received furosemide on days 3 and 4 of life. From these observations we infer that early postnatal phenomena such as excessive fluid therapy may be important in the pathogenesis of BPD.

Theophylline pharmacokinetics in patients with bronchopulmonary dysplasia

Theophylline is commonly used to decrease airway resistance in patients with bronchopulmonary dysplasia (BPD). Little is known, however, about theophylline's pharmacokinetics in infants' with BPD. The objectives of this study were: (i) to examine the pharmacokinetics of theophylline; and (ii) to assess the intrapatient variation in theophylline serum concentration in BPD. Nineteen patients (gestational age: 27-33 weeks, postnatal age: 12-165 days) received 2-12 mg/kg/day theophylline. Multiple serum concentrations of theophylline were determined in each patient. Apparent clearance of theophylline ranged from 0.28 to 0.51 ml/min/kg. The steady-state trough serum concentration of theophylline ranged from 3.5 to 11.2 micrograms/ml. Based on our data, theophylline doses of 4-7 mg/kg/day may be required to achieve an average steady-state serum concentration of 10 micrograms/ml. Substantial intrapatient (twofold) variability was observed in theophylline concentrations normalized for dose during therapy. The data indicate that the theophylline serum concentration should be monitored for individualizing therapy in infants with BPD.

Ligation of the patent ductus arteriosus in newborn respiratory failure

Patent ductus arteriosus (PDA) is commonly associated with respiratory disease in newborn infants and may require ligation. Surgical ligation of the PDA can be done in small infants with low operative risk and minimal complications. The outcome of patients after ligation depends primarily on the severity of the underlying pulmonary disease. One hundred fifty-one patients have undergone ligation in an eight-year period at this center. A simplified technique performed in the neonatal intensive care unit with the use of local anesthesia and conventional ventilator management is described.

Ligation of patent ductus arteriosus in very low birthweight premature neonates

The results of ligation of a patent ductus arteriosus in 30 premature neonates with a very low birth weight were analysed. The mean gestational age at birth was 27 weeks and the mean weight 811 g. Attempted closure of the ductus with indomethacin in 19 infants failed, though there was temporary closure in nine. Congestive heart failure was present in 29 and respiratory distress in 22 patients. Endotracheal intubation with assisted ventilation was necessary in all cases. The mean age at operation was 13.5 days and ductal ligation was performed in the intensive care unit under local anaesthesia supplemented with pancuronium and pethidine. There were no intraoperative deaths, but five infants died in hospital. There were seven late deaths. Eighteen survivors have been followed for a mean of 26.5 months. Early ligation of a patent ductus arteriosus in premature infants with a very low birth weight improved the cardiorespiratory state. Long term follow up showed good clinical progress in two thirds of the surviving group.

Bronchopulmonary dysplasia. Chronic pulmonary disease following neonatal respiratory failure

Infants with respiratory failure in the first weeks of life may develop a chronic pulmonary condition called bronchopulmonary dysplasia. Their lungs have areas of atelectasis and areas of air trapping from variable obstruction of the airways. These infants may be dependent on supplemental oxygen or a ventilator and may require hospitalization for months, and have symptoms of airway obstruction which last for years. They require meticulous medical management to avoid a number of common complications such as patent ductus arteriosus, cor pulmonale, tracheal stenosis, recurrent aspiration, and death. The condition of most infants improves over the first two years. Preliminary studies suggest that their exercise and pulmonary function is usually close to normal by school-age. The long-term implications for the increasing number of children with this disease who will soon reach adulthood are still unknown.

Hemodynamically significant PDA: an echocardiographic and clinical assessment of incidence, natural history, and outcome in very low birth weight infants maintained in negative fluid balance

Fifty very low birth weight (VLBW) infants (750-1500 g, 27-33 weeks gestational age) were assigned at random to one of two groups of negative fluid balance and underwent prospective clinical and echocardiographic examinations during the first month of life. The purpose was to determine: the effect of fluid restriction on the incidence of ductal shunting, the reliability of the physical examination in diagnosing significant ductal shunting, and the relationship between significant ductal shunting and outcome in such infants. None of the infants had manipulations to close the ductus during the first week of life. Using routine structural and functional echocardiographic indices as criteria for the diagnosis of hemodynamically significant ductal shunting (hsPDA), we found that the two fluid-balance groups (8%-10% weight loss vs 13%-15% weight loss) did not significantly differ in incidence of hsPDA, duration of ventilation, or development of BPD. These two groups were then combined for further analysis: 32 (64%) of 50 VLBW infants had hsPDA during the first week of life. The group of infants with hsPDA did not differ significantly from that without hsPDA in birth weight or gestational age, but had a significantly lower Apgar score (P less than 0.04) and was significantly more likely to require ventilator support for RDS (P less than 0.01). Although when present a typical ductal murmur was specific for the development of significant ductal shunting, no murmur was heard in 21 (66%) of 32 infants with early hsPDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Indomethacin versus immediate ligation in the treatment of 82 newborns with patent ductus arteriosus

In the past 10 years, echocardiography and prostaglandin inhibition have changed the management of the patent ductus arteriosus (PDA) in newborns with respiratory distress syndrome (RDS). To judge the results of our present management for morbidity and survival, we analyzed data retrospectively on 82 newborns who were treated from 1977 to 1983 for PDA. We compared their hospital courses and outcomes with a similar group of 45 infants reported by us 10 years ago who were treated by early ductal ligation. The 82 recent patients were divided into two groups, A and B. Group A, 62 consecutive newborns with PDA, was treated primarily with indomethacin. A subsequent group of 20 newborns was treated for PDA primarily with early ductal ligation, group B. There was a 67.8% survival in group A versus 66.7% in the original group of patients 10 years ago--no significant improvement in survival in recent patients using indomethacin. Group B, with early ductal ligation similar to the original patients, had a survival rate of 75%. We identified a group of high-risk infants under 1500 grams with severe RDS whose prognoses varied significantly, depending on the treatment. In the original patients 10 years ago, 41.2% of newborns under 1500 grams with severe RDS survived; 33.3% survived in group A whereas, 71.4% survived in group B. In this high-risk group, treatment for PDA with indomethacin had the worst prognosis, and treatment with ductal ligation combined with modern supportive measures had the best prognosis.

Effects of indomethacin in premature infants with patent ductus arteriosus: results of a national collaborative study

Among 3559 newborn infants with birth weight less than 1750 gm, 421 developing a hemodynamically significant patent ductus arteriosus were entered into a randomized trial to evaluate the role of indomethacin in the management of PDA. Indomethacin given concurrently with usual medical therapy at the time of diagnosis resulted in ductal closure in 79%, versus 35% with placebo (P less than 0.001). Indomethacin as backup to usual medical treatment resulted in similar closure rates. To assess overall effects through hospital discharge, three management strategies were compared. Although mortality did not differ significantly, infants given indomethacin only if usual therapy failed (strategy 2) had a lower incidence of bleeding than those to whom indomethacin was given with initial medical therapy (strategy 1) and lower rates of pneumothorax and retrolental fibroplasia than those to whom no indomethacin was administered, with surgery the only backup to medical therapy (strategy 3). Thus the administration of indomethacin only when medical treatment fails appears to be the preferable approach for the management of symptomatic PDA in premature infants.

Early closure of patent ductus arteriosus with indomethacin in preterm infants with idiopathic respiratory distress syndrome

Thirty-seven preterm infants with idiopathic respiratory distress syndrome were prospectively studied for the effect of the early closure of patent ductus arteriosus with indomethacin on the course of idiopathic respiratory distress syndrome. Serial retrograde aortograms were performed in all infants in order to visualize the ductus arteriosus, apart from three patients, who died early and were evaluated aortographically only once. The ductus was initially open in 27 infants and closed in 10 infants. The infants with open ductus arteriosus were randomly divided into two groups. The first group consisted of 13 infants, in whom the ductus was closed with indomethacin at a median age of 18 hours. The other 14 infants served as controls. Total time on assisted ventilation and duration of exposure to additional oxygen were significantly shorter in medicated infants than in controls. Oxygenation of infants with an initially closed ductus was better from birth and duration of their ventilatory assistance and oxygen exposure were shorter than in infants with initial ductal shunting. The data suggest that the early closure of the patent ductus arteriosus with indomethacin in distressed preterm infants has a favourable effect on the course of idiopathic respiratory distress syndrome.

Patent ductus arteriosus in premature infants: a review of current management

Problems related to the ductus arteriosus confront the pediatrician more than any other isolated cardiac defect. Due to increased awareness of the problems of prematurity, the reported frequency of patent ductus arteriosus increased threefold between 1970 and 1975. Aggressive therapy directed toward closure of the ductus is indicated within the first week of life in the very immature infant. Pharmacologic closure of the PDA with indomethacin is effective about half the time.

Surgical treatment of patent ductus arteriosus in preterm infants. Four-year experience with ligation in the newborn intensive care unit

Seventy-nine consecutive patent ductus arteriosus (PDA) ligations were performed in our newborn intensive care unit (NBICU) over a four-year period. Seven infants (9%) died within one month after surgery. The deaths were not attributed to the surgery but were associated with preexisting medical complications or new intracranial hemorrhages. Significant surgical morbidity was rare. We conclude that ligation of the PDA in the premature infant can be a safe and effective procedure, when pharmacologic closure is ineffective or contraindicated. Furthermore, PDA ligation may be safely performed in the NBICU.

Ligation of patent ductus arteriosus in very low birth weight infants

Twenty-five low birth weight, premature neonates who were refractory to aggressive medical management underwent ligation of symptomatic patent ductus arteriosus. The mean birth weight was 1,007 g and the mean gestational age 29 weeks. Six patients (24 percent) died before discharge, two from continued cardiorespiratory failure. Echocardiography showed significant improvement in left atrial and left ventricular dimensions after ligation. In the premature neonate with respiratory distress and congestive heart failure refractory to aggressive medical management, surgical ligation may be accomplished with an acceptable hospital mortality in very low birth weight infants.

Surgical management of patent ductus arteriosus in newborn infants of low birthweights. A review of 33 cases

Thirty-three infants with low birthweights (<2500 g) and respiratory distress had ligation of a patent ductus arteriosus. During a 30-month period there were no deaths resulting from the operation, but 11 (33%) eventually died from complications of immaturity.

Management of patent ductus arteriosus in preterm babies

There is a higher incidence of delayed closure of the patent ductus arteriosus in premature babies with respiratory distress syndrome. From July, 1975, to December, 1977, 57 small, preterm infants with patent ductus arteriosus were diagnosed at our neonatal intensive care unit. From July, 1975, until September, 1976 (first period), 23 patients were diagnosed, and 11 underwent surgical ligation of a patent ductus arteriosus. There were 3 early deaths. From October, 1976, until December, 1977, out of a total of 34 patients with diagnosed patent ductus, 18 were treated with indomethacin, and only 3 required ligation. Our present policy for patent ductus arteriosus with respiratory distress syndrome in the premature baby is to initiate early treatment with indomethacin. If this treatment fails and the infant's status deteriorates, we perform early surgical ligation of the ductus in order to minimize the time on mechanical ventilation and lessen the chances of the development of bronchopulmonary dysplasia.

The anaesthetic management of preterm infants undergoing ligation of patent ductus arteriosus

The authors reviewed the records of seventy preterm infants suffering from respiratory distress syndrome and, in most cases, refractory congestive heart failure, who underwent ligation of patent ductus arteriosus. The peri-operative management of these patients is described. The anaesthetic technique consisted of nitrous oxide and oxygen supplemented with a relaxant. All patients were ventilated manually with a humidified Jackson Rees system. The operations were performed in the main operating suite. There were no deaths during operation. The infants were protected from significant temperature fluctuations by various methods which are described. The overall survival rate of all preterm infants with respiratory distress syndrome. The management presented is considered acceptable to the infants, to the surgeons and to the anaesthetists.

Pharmacological closure of ductus arteriosus in preterm infants using indomethacin

Patent ductus arteriosus (PDA) was diagnosed in 27 (21%) of 129 infants weighing [unk] 1500 g at birth presenting over 1½ years. The incidence of PDA in infants with pulmonary disease, particularly hyaline membrane disease, was higher than that in infants without such disease (31% compared with 16%). 16 (59%) infants with PDA developed congestive cardiac failure (CCF), of whom 12 were [unk] 1000 g at birth. Eight of these infants had persistent CCF despite aggressive antifailure treatment, and 8 were ventilator-dependent although stable on medical management. Pharmacological ductal closure with indomethacin was attempted in these 16 infants according to clinical and echocardiographic criteria. Complete or partial ductal closure with clinical and echocardiographic improvement was achieved in 75% of infants. Treatment with indomethacin failed in 4 infants all of whom were [unk] 1000 g at birth and had gestational ages [unk] 26 weeks. Two of these infants had surgical ligation of the PDA and recovered. No morbidity was attributed to indomethacin except for transient oliguria. Overall survival was 76%; this ranged from 50% in infants weighing 501-750 g, to 91% in infants weighing 1251-1500 g. Results suggest that (1) extremely preterm infants are less likely to respond to indomethacin, (2) success is more likely in the first 10 days of life, (3) a total dose greater than 0·6 mg/kg will not increase the success rate, (4) selective morbidity from indomethacin is unlikely if the contraindications of bleeding tendency, hyperbilirubinaemia, and renal dysfunction are followed, although urinary output must be monitored carefully, (5) indomethacin is a useful alternative to surgical ligation although long-term prognosis from clinical trials has yet to be established.

Artificial surfactant therapy in hyaline-membrane disease

Ten preterm infants severely ill with hyaline-membrane disease (HMD) were given artificial surfactant endotracheally. Oxygenation and alveolar-arterial oxygen gradients improved, the levels of inspired oxygen and peak respirator pressure could be reduced, and many of the radiological abnormalities resolved. Acidosis and systemic hypotension were also reversed. In nine infants a patent ductus arteriosus became evident after recovery from HMD, necessitating further assisted ventilation. Eight infants survived, including five of six with birthweight less than 1500 g; two died of unrelated causes. Postnatal tracheal instillation of artificial surfactant may prove a useful treatment for severe HMD.

Patent ductus arteriosus treated with ligation or indomethacin: a follow-up study

The course and complications of fifty-two infants with patent ductus arteriosus requiring closure were assessed prospectively. Twenty-six infants with a PDA received indomethacin for pharmacologic closure of the PDA, and 26 underwent ligation. The current study analyzes and compares the longitudinal follow-up with respect to somatic growth, neurologic function, psychomotor and mental development, and renal, ophthalmologic, and audiologic function in 21 infants in each group who entered the follow-up. No selective morbidity was attributable to PDA closure with indomethacin when compared to surgically treated infants.

A rational approach to ligation of patent ductus arteriosus in the neonate

During a 23-month period, 25 premature infants underwent ligation of a patent ductus arteriosus performed in the neonatal intensive care unit utilizing a limited posterolateral muscle-retracting incision. This approach afforded adequate exposure with minimal surgical time and trauma. All infants manifested severe respiratory distress and congestive heart failure. Both standard and contrast echocardiographic studies were used for noninvasive preoperative evaluation. Echocardiographic study proved to be a highly reliable and sensitive indicator of ductal patency. Eight infants (32 percent) died at 8 to 225 days of age. The primary cause of death was progressive pulmonary disease with subsequent failure of multiple organ systems. Seventeen (68 percent) of the 25 infants survived to leave the hospital. Advantages of ligation of a patent ductus arteriosus in the neonatal intensive care unit include the elimination of problems of transportation (thermoregulation, ventilation, and loss of lines) and continuity of ongoing care and monitoring. The standard facilities of the neonatal intensive care unit proved completely satisfactory for ligation of a patent ductus arteriosus. Ligation in the neonatal intensive care unit is suggested to minimize potential complications of care in the operating room and transport of these critically ill infants.

Conservative management of patent ductus arteriosus in preterm infants

We report our experience of medical treatment, chiefly based on prolonged artificial ventilation, of 33 preterm infants with PDA and heart failure whose survival rate was 88%. All of them had clinical criteria used by others to indicate surgical ligation of the ductus arteriosus. This conservative approach seems to give better results than surgical ligation, despite a high frequency of bronchopulmonary dysplasia among survivors.

Operation or indomethacin for the premature ductus

Indomethacin constricts the patent ductus arteriosus in approximately 70% of premature infants, but temporarily inhibits synthesis of all prostaglandins. Early toxicity of indomethacin is not prohibitive, but the possibility of late neurological deficits is raised by results of laboratory experiments. As yet, no late toxic effects of indomethacin have been observed. However, this possibility and the low morbidity (less than 2%) and mortality (less than 2%) of surgical ligation of the patent ductus arteriosus in premature infants favor operation except in carefully controlled and limited clinical trials.

The silent ductus arteriosus

Preterm infants at risk of developing a patent ductus arteriosus were followed sequentially by physical examination, echocardiographic determinations of the LA/AO ratio, and chest roentgenograms. The results show that a significant number of infants who have no clinical signs or symptoms of a PDA have large left-to-right shunts. The presence of this shunt was suggested by acute increase in left atrial size by ECHO determination and confirmed by retrograde single-film aortography. Clinical signs and symptoms often developed several days after documentation of the left-to-right shunt.

Bronchopulmonary dysplasia: possible relationship to pulmonary edema

The pathogenesis of bronchopulmonary dysplasia is controversial. Oxygen toxicity, mechanical trauma to the lung secondary to respirator therapy, and congestive heart failure with a left to right shunt through a patent ductus arteriosus have all been implicated. Our data suggest that in addition to these three conditions, all of which are edemagenic, infants with bronchopulmonary dysplasia have a significantly greater mean fluid intake in the first five days of life when compared with infants with respiratory distress syndrome or patent ductus arteriosus alone. We suggest that the addition of a fluid load may potentiate the effects of other factors and increase the risk of bronchopulmonary dysplasia in infants with respiratory distress syndrome who require respiratory support.

"Acquired" lobar emphysema: a complication of respiratory distress in premature infants

Ten premature infants with respiratory distress developed a type of pulmonary lobar emphysema that is clinically and histologically distinct from interstitial or congenital lobar emphysema. In eight patients emphysema was noted in the right lower lobe, while in two the left upper lobe was affected. Five infants exhibited nonresolution of the emphysema and an inability to be weaned from ventilator support. Lung scans in these five infants showed absent or markedly decreased perfusion of the involved lobe. Lobectomy was necessary. Postoperatively, their respiratory status improved and they were successfully weaned from the ventilator. Five premature infants with identical radiographic emphysematous changes had normal lung scans. These infants did not require lobectomy and were also successfully weaned from the ventilator. Radiographic changes of lobar emphysema in these five infants completely resolved. Pathologic changes in the excised lobes were characteristic of bronchopulmonary dysplasia and obstructive intraalveolar emphysema. The long-term effects of positive pressure ventilation, oxygen, and suctioning techniques directed toward the right lower lobe may play an important role in the etiology of "acquired" lobar emphysema.

Influence of continuous positive airways pressure treatment on ductus arteriosus shung assessed by echocardiography

In a preterm infant with the respiratory distress syndrome complicated by patent ductus arteriosus, continuous positive airways pressure (CPAP) treatment relieved the signs of cardiac decompensation associated with left-to-right shunt. Echocardiography enabled the change in left atrial size, an indirect measure of the shunt, to be followed. In this way the rapid effect of CPAP in reducing left-to-right shunting could be monitored. This noninvasive technique could have many applications in neonatology.

Ligation of the patent ductus arteriousus in the newborn intensive care unit

During a two-year period, 21 premature infants (weight at birth, 680 to 2,340 gm) had operative closure of patent ductus arteriosus (PDA). The first 6 infants had ligation performed in the operating room (OR); the subsequent 15 had ligation in the Newborn Intensive Care Unit. There were no immediate postoperative deaths. Two infants died from problems presnet preoperatively within 30 days postoperatively. There were no infections. Technique in the unit utilizes an open warmer with local anesthesia and a paralyzing agent. By eliminating transportation to the OR one avoids problems with thermoregulation, loss of lines, malfunction of monitors, poorly controlled ventilation, and fluid overload. Additional advantages to ligation in the unit are that the infant is already monitored, intubated, and on a respirator, and that venous and usually umbilical arterial lines are in place. At the conclusion of operation, management is returned to the neonatologists for optimal continuity of care.

Interruption of patent ductus arteriosus in premature infants with respiratory distress syndrome

In infants with respiratory distress syndrome (RDS) hypoxemia inhibits closure of the patent ductus arteriosus (PDA), resulting in increased pulmonary blood flow with subsequent increased hypoxemia. In an attempt to interrupt this cycle 42 consecutive premature infants with RDS and PDA, weighing between 550 and 2,000 gm (average, 1,383 gm) and with an average gestational age of 31 weeks, were arbitrarily treated either medically (13 patients) or by interruption of the PDA (20 patients). Eleven patients who were initially treated medically could not be weaned from the respirator and later underwent operation. There were no operative or anesthetic deaths; late survival was 65% (20 patients). The last 31 patients were randomly divided into operative and nonoperative groups. Preliminary results revealed no significant differences in late survival between the two groups. Since the operative risk is minimal, further investigative efforts are indicated to settle this issue.