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Balloon-induced distention of the main pulmonary artery causes acute pulmonary hypertension and reflex pulmonary vasoconstriction in animals. Pulmonary artery pressure responses caused by MPA balloon inflation were measured in ten human newborn infants with cardiac failure (n=5) or persistent fetal circulation (n=5). During balloon inflation distal mean PAP increased significantly while cardiac rate remained unchanged. MPA distention caused greater increases of PAP in those infants with lower resting PAP. The greatest balloon-induced increases of PAP were observed in infants recovering from PFC. The existence of a pulmonary artery stretch reflex and its possible role in the regulation of the human fetal and neonatal pulmonary circulation is discussed.

Rational management of pulmonary artery hypertension (PAH) in the newborn infant must be based on an understanding of underlying causes. When a specific diagnosis can be made, empirical treatment gives way to specific therapy. For every pathophysiologic abnormality potentially resulting in PAH, clinical entities can be identified and key therapeutic interactions can be considered. 1. Pulmonary Venous Hypertension: PAH is secondary to obstruction of blood flow through the left heart. If based on anatomic abnormality (mitral or left atrial), surgical relief of obstruction is required. If PAH is the result or functional abnormality of the left ventricle (transient left ventricular ischemia), medical treatment of left ventricular failure is most important. 2. Functional Obstruction of Pulmonary Vascular Bed: Hyperviscosity of blood (polycythemia - HCT > 65) results in increased pulmonary vascular resistance. Treatment consists of reduction of red blood cell volume. 3. Pulmonary Vascular Constriction: Hypoxemia with or without pulmonary parenchymal disease (primary or secondary persistent fetal circulation [PFC] syndrome). Therapy is directed at improvement of oxygenation and dilatation of pulmonary arteriolar bed (e.g. O2 hyperventilation and/or pulmonary vasodilator therapy). 4. Decreased Pulmonary Vascular Bed: If primary pulmonary hypoplasia is present, no treatment is available. If secondary form (diaphragmatic hernia), surgical repair and pulmonary vasodilatation of contralateral lung is indicated. Extracorporeal membrane oxygenation (ECMO) can be used in severe cases. 5. Increased pulmonary blood flow: Causes in the neonate include complex heart disease without pulmonary stenosis; and peripheral A—V fistula. Treatment: Surgical limitation of pulmonary blood flow may be required. Even when PAH is the result of combined etiologies, a prompt well-organized clinical management plan can follow from understanding of pathologic principles.

Prior to echocardiography, the recognition of serious heart disease in the cyanotic newborn or young infant could be extremely difficult. The profound hemodynamic changes taking place in the heart and lungs after birth influence the clinical manifestations of many cardiac disorders, and sometimes suggest the existence of a cardiac disorder when none is present. Real time echocardiography has revolutionalized the diagnosis of the cyanotic infant. If the reason for the infant's cyanosis or respiratory distress is not apparent from the history, physical examination, laboratory values, and chest radiograph; real time echocardiography should be performed to exclude or diagnose cyanotic congenital heart disease and persistent fetal circulation. This will prevent misdiagnosis in cyanotic infants and assure rapid and appropriate treatment.

Before the mid 1970s, neonates with diaphragmatic hernias (CDH) had a survival rate of 40%. Since then increased interest has been focused on the pulmonary artery and its hypertension (the persistent fetal circulation) and the pharmacologic treatment of this pathophysiology. Our initial pharmacologic experience left us with much information and even more unanswered questions. While other series were encouraging, they also showed a survival rate of about 50%. The following problems are associated with pulmonary vasodilator therapy: (1) there is no specific pulmonary vasodilator and the response is often unpredictable; (2) the pulmonary arterioles in these babies are abnormal and appear in many instances anatomically incapable of responding; (3) cardiac output may be affected secondary to inotropic or chronotropic side effects of vasodilators; and (4) the effect of a vasodilator on the pulmonary vasculature under hypoxic conditions is unknown. Moreover, we have yet to identify at birth which CDH babies require this treatment, and we must find improved pharmacologic agents that will more specifically dilate the constricted pulmonary vascular bed with minimal effect on the systemic circulation. Although some attempts at pharmacological manipulation of the pulmonary vascular bed continue in most centers, including ours, there are many other innovations in the perioperative management which require further evaluation, among them extracorporeal membrane oxygenation, high-frequency oscillation and possibly lung transplantation in the future.

We treated 13 cases of neonatal Bochdalek's hernia at the 1st Department of Surgery, Hiroshima University Hospital in the 6 years from 1978 to 1983 and have studied on the factors responsible for mortality of neonatal Bochdalek's hernia. The following conclusions were obtained in this study. 1. Of the 13 patients, 7 survived and 6 died. The most frequent cause of death was persistent fetal circulation, the cause of 5 of the deaths. 2. All 3 of the premature newborns died. 3. The earlier the time of onset of symptoms, the higher was the mortality. 4. Five of the 7 patients who required respiratory control by intubation before hospitalization died. 5. The mortality rate for patients with pH less than 7.00, base excess less than－15 mEq/liter, and M index higher than 6 on admission was extremely high. 6. Three of the 7 patients persisting a distinct pressure difference on simultaneous measurement of preductal PaO2 and postductal PaO2 died. In the surviving patients, it was possible to maintain the postductal PaO2 at above 60 mmHg. 7. Trazoline was used on 2 patients, and both died. A thorough study of the time and mode of administration is considered to be necessary.

The clinical course and histologic findings are presented of an infant with an unusual form of pulmonary dysplasia. Characteristic sonographic findings and progressive hypoxemia led to the diagnosis of persistence of the fetal circulation. The patient expired despite ventilatory and pharmacologic intervention. Postmortem findings of severe pulmonary capillary hypoplasia, despite normal anatomical and biochemical parenchymal maturation, were observed. It is suggested that factors controlling pulmonary capillary maturation may be significantly different from those involved in airway and pulmonary parenchymal development.

Persistent pulmonary hypertension may be a contributing factor to many pulmonary diseases in the newborn; but the diagnosis persistent fetal circulation is usually reserved for those infants in whom the pulmonary hypertension is accompanied by minimal or no lung disease. The infants are usually at or near term and show clinical signs of cyanosis (even with oxygen therapy), a variable degree of respiratory distress and clinical signs of right ventricular strain (parasternal heave and active precordium). X-ray appearances are very variable. Characteristically clear lung fields indicative of under-perfusion are seen, but frequently the lung fields are abnormal and the appearances non-specific. The cardiac outline is usually normal.

A case of lithium intoxication in the newborn is presented. Besides displaying extreme hypotonia and a goitre, the infant developed symptoms of congenital heart disease immediately after birth. Cardiac catheterization and angiocardiography revealed an elevated pulmonary vascular resistance and indicated that the cardiopulmonary symptoms were caused by persistent fetal circulation. Previously, four authors have independently reported cardiopulmonary symptoms in association with lithium intoxication without finding cardiac or pulmonary disease. The similarity between the present and the four earlier reported cases in regard to the symptoms and the course of illness, raises the question of the connection between lithium intoxication and persistent fetal circulation being more than coincidental. In view of recent investigations it is speculated that lithium intoxication in utero may result in the pulmonary vascular changes responsible for the persistence of fetal circulation.

A newborn infant presented with cardiac failure secondary to a peripheral cavernous haemangioma. She was successfully treated surgically but was later diagnosed as having GM1 gangliosidosis.

A female neonate who had been diagnosed as having congenital diaphragmatic hernia by ultrasonography was delivered by cesarean section. After the hernia was repaired, she developed hypoxemia and hypercapnia, probably due to persistent fetal circulation (PFC). Neither conventional mechanical ventilation (CMV) nor manual ventilation improved the respiratory status. High-frequency oscillation (HFO) successfully improved pulmonary gas exchange, but we failed to wean the patient from HFO by using intermittent HFO. The patient was again placed on CMV for weaning and was extubated on the 12th ICU day. We conclude that HFO can be an alternative respiratory modality in patients with respiratory failure due to PFC after the repair of congenital diaphragmatic hernia.

High-risk infants with a fetal pattern of circulation demonstrate hyperactivity of the pulmonary vascular bed in response to stimuli including mucous plugging, atelectasis, and endotrachial tube suctioning. The resultant increase in pulmonary vascular resistance (PVR) leads to pulmonary hypertension, severe right-to-left shunting, and hypoxemia. Stimuli that trigger pulmonary hypertension cause hypoxia, suggesting the importance of hypoxic pulmonary vasoconstriction (HPV). Although many humoral mediators of HPV have been hypothesized, none have been proven. This study investigates the possible role of the cyclo-oxygenase derivatives thromboxane A2 and prostacyclin as determinants of hypoxic pulmonary hypertension. Open-chested lambs were ventilated with 13% O2 prior to and following treatment with OKY 046, a selective thromboxane inhibitor. In untreated lambs, the partial pressure of arterial oxygen fell from 80 +/- 27 (mean +/- SD) to 35 +/- 13 mm HG (P less than .01). The mean arterial pressure (MAP) remained at 50 +/- 7 mm HG, and the cardiac output (CO) was unchanged at 0.8 +/- 0.2 L/min. The mean pulmonary arterial pressure (MPAP) rose from 11 +/- 4 to 20 +/- 4 mm HG (P less than .01) whereas the PVR increased 70% (P less than .01). TxB2 rose from 147 +/- 85 to 271 +/- 154 pg/mL (P less than .05), and 6-keto-PGF1 alpha rose from 105 +/- 96 to 142 +/- 110 pg/mL. These substances are the hydrolysis products of TxA2 and prostacyclin respectively. In animals treated with OKY 046 prior to ventilation with 13% O2, values for MAP, CO, and PVR were similar to those of the nontreatment period.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital Posterolateral Diaphragmatic Hernia is associated with ipsilateral pulmonary hypoplasia and blood flow to the affected lung remains diminished into late childhood. 1 Although this unilateral pulmonary hypoplasia is physiologically significant, it is probably not primarily responsible for the high mortality of congenital diaphragmatic hernia. The major immediate threat to a baby's life is the tension effect of the herniated abdominal viscera, but even after successful reduction of these organs, a greater than 50% mortality occurs. The mortality and morbidity is often due to continuing and progressive hypoxemia and metabolic acidosis. Several authors 2–4 have reported pulmonary hypertension, patent ductus arteriosus and variable right-to-left shunting in babies with diaphragmatic hernias. Right-to-left shunting via a patent ductus may contribute significantly to increasing hypoxemia and acidosis in addition to the efect of pulmonary hypoplasia. To test this hypothesis, we have developed a simplified fetal model to simulate diaphragmatic hernia and permit studies of pulmonary and ductal hemodynamics. The fetal lamb was chosen for studies of the pathophysiology of diaphragmatic hernia because pulmonary development in fetal lambs occurs late in gestation and because many studies have been made of normal pulmonary function in newborn lambs. 5–8 This cumulative data is available for comparison with laboratory models of pulmornary abnormalities. These studies were therefore designed to test our belief that right-to-left shunting via the patent ductus arteriosus (PDA) is due to persistent fetal circulation and associated with altered blood flow to the hypoplastic lung.

Three infants died with pulmonary hypertension of unknown cause during the first three months of life. Their lungs were examined using quantitative morphologic techniques. In all three cases the intra-acinar pulmonary arteries were more muscular than normal, as shown both by an increase in thickness of the muscle coat in arteries which are normally muscular, and by extension of muscle into smaller and more peripheral intra-acinar arteries not normally muscular at this age. It is suggested that "persistent pulmonary hypertension" of the newborn infant is, in some infants, due to a structural abnormality of the pulmonary circulation which is present at birth.

The differential diagnosis of congenital heart disease from persistent fetal circulation is clinically difficult and cardiac catheterization is often needed. The development of a safe, new technique for use of the rebreathing method has allowed the determination of effective pulmonary blood flow, lung tissue volume, lung diffusion capacity and functional residual capacity in 7 critically ill, ventilator-dependent infants at the bedside. Analysis of the data revealed highly significant differences for lung tissue volume and diffusion capacity, a minimally significant difference for effective pulmonary blood flow and no difference for functional residual capacity between the groups. Use of this method allows not only attainment of clinically useful information but also permits better insight into the pathophysiology of the disease state.

Persistent fetal circulation may be primary or secondary to other causes. Apart from treating the underlying cause, its management may include ventilatory support and the use of vasodilators, whose value may be limited by marked systemic hypotension. Milrinone is a new cardiotonic agent with smooth muscle-relaxant properties. Unlike its predecessor amrinone, milrinone is less likely to be limited by tachyphylaxis. We evaluated the effect of Milrinone on the neonatal pulmonary circulation in conscious newborn lambs; in particular, on the pulmonary arteriolar constrictor effect of leukotriene D4 (LTD4) during normoxia and hypoxia.

Several studies found a significant association between patent foramen ovale (PFO), interatrial septal aneurysm, and patients less than 60 years of age presenting with acute stroke and without any identified coexisting mechanism explaining the acute event. Paradoxical embolism from a venous source through a right-to-left shunt is usually incriminated, but the definite proof for paradoxical embolism is often lacking, with screening for deep-venous thrombosis leading to variable estimates. Despite these controversies, the-possibility of paradoxical embolism in patients with cryptogenic stroke and PFO is commonly retained as the cause of the neurological deficit. Moreover, there are now definite studies documenting that these patients are at risk of recurrence. The aim of the present paper is to review the literature on the risks of stroke recurrence in patients with atrial septal defects, and to weigh the risks and benefits of the different therapeutic options currently available to prevent stroke recurrence. These options include chronic oral anticoagulant or antiplatelet therapy, and more invasive procedures such as surgical closure or transcatheter closure of the defect. Finally, using the principles of decision analysis, the authors suggest tentative practical therapeutic recommendations that might be helpful to clinicians in daily practice.

A neonate severely ill with pulmonary hemorrhage improved on intravenous tolazoline. We suggest that persistent fetal circulation may complicate this disorder and that vasodilator theapy is justified when other therapeutic measures fail.

• Forty children who had persistent fetal circulation (PFC) were followed up for one to four years. At the most recent examination, 16 (40%) were normal, eight (20%) had neurosensory hearing loss, three (7.5%) were profoundly impaired, six (15.0%) had suspect or abnormal results of neurologic examinations exclusive of hearing loss, three (7.5%) had speech impairment and normal hearing, and one had a delay in motor development. The remaining three had clinically suspect speech. Neurosensory hearing loss correlated only with having a mother with insulin-dependent diabetes, hand-to-mouth facility on the Brazelton scale, and eight-month neurologic status. Earlier diagnosis of hearing loss may be facilitated by testing of neonatal auditory behavioral responses, neurologic status at eight months, and by attention to parental concern about abnormal speech development. Neonatal and infancy auditory screening are recommended in children who have PFC in the neonatal period. (AJDC1985;139:25-28)

A retrospective analysis of 93 consecutive children with congenital posterolateral diaphragmatic hernia (CDH) was performed to determine outcome, ability to predict the development of persistent fetal circulation (PFC) requiring pharmacologic or extracorporeal membrane oxygenation (ECMO), and whether drugs or ECMO have improved survival. No patient died who was more than 24 hours of age at operation. Of 66 (71%) infants who were younger than 24 hours, 38 (58%) died. Preoperative and postoperative alveolar-arterial oxygen differences (AaDo2) did not consistently predict survival or death. Pharmacologic management of PFC in 30 patients resulted in a temporary improvement in 13 (43%). Survival was attributable to drugs in only seven (23%). ECMO was used in eight patients, all of whom had failed to improve with pharmacologic therapy and had a 100% predicted mortality rate based on the Neonatal Pulmonary Insufficiency Index. All eight had temporary improvement, while five (62%) completely cleared the PFC and four (50%) survived. Significant complications occurred in six patients. Earlier and more reliable methods of predicting high-risk infants are needed. Pharmacologic manipulation of PFC associated with CDH did not significantly improve survival. ECMO may prove to be a useful means of supporting these infants until more effective ventilatory and pharmacologic methods become available.

SummaryBackgroundRarely, hypoxaemia is associated with shunt reversal at the atrial level. Closure by interventional catheterization is the treatment of choice but indications and results have been studied insufficiently.PurposeTo describe our experience with interventional closure of atrial right-to-left shunts described as hypoxaemic and the impact on patient oxygenation and clinical status.MethodRetrospective study in two referral centres, including all patients undergoing closure of interatrial right-to-left shunt associated with hypoxaemia.ResultsSince 2001, 21 consecutive patients underwent interventional shunt closure using the “Amplatzer® device”; two patients had atrial septal defect and 19 had patent foramen ovale. Three patients had minor adverse events; two patients have a tiny residual shunt. Transcutaneous oxygen saturation and partial oxygen pressure increased significantly from 86±5 to 95±3% (p

J Thorac Cardiovasc Surg 2003;125:S85-6

Animal studies have demonstrated that acute blood loss may produce an increase in pulmonary vascular resistance. We postulate that hypovolemia may be one factor in the etiology of persistent fetal circulation (PFC). Circulating red cell volume (using 51 Cr labeling techniques) was measured in 5 neonates who presented with clinical findings of PFC (tachypnea, extra-pulmonary right-to-left shunting and normal cardiovascular anatomy at catheterization and/or autopsy). Birth weights of the 5 infants ranged from 2420-4140 (mean 3772) grams; gestational ages were 35-41 (mean 39) weeks, and all infants had normal 5-minute Apgar scores. Blood loss was not suspected in any of the 5 infants, nor were any transfused prior to their red cell volume studies. The initial hematocrits, glucose concentrations and calcium values were ≥ 55%, ≥ 95mg/dl, and ≥ 7.8mg/dl respectively. Four of the 5 infants expired despite vigorous resuscitative efforts, including transfusion. Red cell volume in all infants was deficient (30-42%, mean 36%). These data suggest that diminished circulating red cell volume may be involved in the etiology of persistent fetal circulation.

In spite of advances in neonatal surgery, the mortality rate from diaphragmatic hernia (DH) remains high. Infants with the early onset of symptoms are at greatest risk and die of hypoxia in spite of successful repair of the defect. The objective of this study was to determine the incidence and to identify factors leading to hypoxemia and death in these infants. Of 21 infants born with DH in our hospital during the last 7 years, 13 had respiratory distress from birth. Nine (70%) of these 13 infants had persistent fetal circulation (PFC) which terminated in death in 6 (46%) infants. PFC was characterized by elevated right atrial pressure, hypoxemia in the descending aorta in spite of inhalation of 100% oxygen and evidence for right-to-left shunt at atrial or ductal levels. In patients who died, progressive hypoxemia and metabolic acidosis were accompanied by severe peripheral vasoconstriction, poor skin perfusion and systemic hypertension. In this study, PFC was the major cause of death in infants with DH. PFC occurred commonly and exclusively in infants whose symptoms were present at birth. Unless PFC is recognized early and reversed by vigorous treatment, the infants will die as a result of progressive hypoxemia and metabolic acidosis.

In 1982-83 7 neonates in 2 hospitals have developed sloughing of tracheal mucosa while on assisted ventilation. Gestation ranged from 26-40 wks; weight from 0.9-3 kg. Primary diagnosis was RDS in 4, persistent fetal circulation in 2 and aspiration in 1. 5 died at 1-4 days of age. At autopsy a thick basophilic membrane of necrotic epithelium and submucosa involved the distal part of the trachea and bronchi totally obstructing the airway in 2 patients. Repeated bronchoscopy in the survivors removed the obstructive plugs. Clinically all cases showed upper airway obstruction with poor chest movement, air trapping and severe CO2 retention. Pressure limited conventional ventilators were used initially followed by a trial of high frequency oscillation in 3. Peak pressures >35 cmH20 were used in 6. Hand bagging using dry 100% O2 was given for periods of 10-90 min. to all.

1337 SELECTION OF INFANTS WITH PERSISTENT FETAL CIRCULATION (PFC) FOR EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO)

This book emphasizes the clinical approach to neonatal medicine and provides ample theory and facts, avoiding a cookbook approach. There are three distinctly different portions of the book. Part 1 deals with general aspects of neonatal care, beginning in the delivery room with the initial newborn examination, the obstetric history, resuscitation, stabilization, and initial screening tests. Infant nutrition and care of the normal newborn and, importantly, of the family are emphasized, and an orderly and comprehensive discussion of discharge instructions and "before the first visit" newborn care is provided. The common newborn problems of sepsis, respiratory distress, jaundice, hypoglycemia, persistent fetal circulation, seizures, necrotizing enterocolitis, and surgical emergencies are adequately covered. Cyanotic congenital heart disease and congestive heart failure are sparsely covered, and two important and common problems of the very-low-birth-weight infant, intracranial hemorrhage and patent ductus arteriosus, are not discussed at all. The most serious criticism of this section

• Sixty neonates who were transferred to a neonatal intensive care unit during a four-year period had diagnoses of persistent fetal circulation (PFC). Six of these 60 neonates had β-hemolytic streptococcal infection. The clinical appearance of these six neonates included respiratory distress, cyanosis, and/or apnea. The chest roentgenograms showed mild to moderate lung disease. All six neonates had progressive acidosis with hypoxemia. The diagnosis of PFC was made by cardiac catheterization or contrast echoangiography. The neonates were treated with mechanical ventilation, antibiotics, and supportive therapy, including tolazoline hydrochloride. Mortality was high; only one of the six neonates survived. Streptococcal infection should be added to the growing list of conditions associated with PFC. ( Am J Dis Child 1982;136:725-727)

Although it is suggested that vasoconstriction is responsible for the pulmonary hypertension and persistent fetal circulation (PFC) associated with meconium aspiration(MA), this has not been proven. We therefore studied the pulmonary vascular bed(PVB)of 10 consecutive term newborns(NB)in whom MA was diagnosed in life and confirmed at autopsy. The pulmonary arteries were injected with barium-gelatin before inflation fixation. Morphometric analysis of three structural features of the PVB: 1)Extension of muscle(EM) into small arteries, 2) Percentage medial wall thickness(%WT),and 3) Arterial concentration(AC)was performed. The findings were compared to those of normal fetal and neonatal lungs. The case histories were also reviewed. In 9/10 NB,PFC was evident clinically-in 8/10 right-to-left shunting at atrial level was confirmed by contrast echocardiography and in 7/10 shunting at ductal level was detected by a decrement in PaO2 ≥ 20 torr from right radial artery to descending aorta. All 9 NB with PFC had EM and increased %WT of the intraacinar arteries with severe encroachment upon the arterial lumen. The NB without PFC had normal arteries. AC was normal in all. The high correlation between fatal MA and PFC was unexpected. The structurally abnormal PVB found in all NB with MA and PFC could not have been caused by vasoconstriction alone and was similar to that seen in PFC without MA. This suggests a common cause of in utero maldevelopment of the PVB and perinatal MA.

We have reported (Bucciarelli et al., Pediatrics, in press) 14 newborns stressed by acute birth hypoxia (and/or hypoglycemia) who developed congestive heart failure, tricuspid insufficiency, and electrocardiographic evidence of myocardial ischemia. Two infants died, each showing tricuspid papillary muscle infarction at autopsy. Subsequently, 13 more stressed newborns, clinically suggesting MD with TTI, have had determinations made of total CPK. Ten had a final clinical diagnosis of MD with TTI. In 9, total CPK was elevated (mean 874 IU/1), in 6 of whom the CPK-MB fraction was elevated to a degree consistent with acute myocardial infarction (mean 185 IU/1). Four of the 10 having MD with TTI died; 2 of these had elevated CPK-MB and papillary muscle infarction; 2 had normal CPK-MB and no infarction at autopsy. Three of the 13 studied had other final diagnosis; (1 with persistent fetal circulation, 2 with congenital heart disease). All had lower mean CPK (107 IU/1) and all had CPK-MB fractions

Little epidemiologic attention has been given to infants ⩾ 2500 gms. admitted to NICU's. To determine their morbidity and mortality, we reviewed all admissions for 17 months and they represented 44% (236/545) of the admissions and 37% of all deaths. The diagnoses were: Pulmonary disease (PD) other than meconium aspiration syndrome (MAS) (32%) ; asphyxia (As) (22%) ; congenital anomalies & heart disease (CA/CHD) (21%) ; surgical (11%) ; sepsis (5%) ; others (9%) . MAS occurred in 44% (22/50) of As infants. Mortality rate was 17% (40/236). Of the deaths, 70% were due to CA/CHD, 23% to As and 7% to sepsis. Of the 9 As deaths, all were > 42 wks. and 8 had MAS. Of 21 cases with persistent fetal circulation (PFC), 17 had As, 16 were > 42 wks and 7 (33%) died. In infants with PFC, As and MAS who were > 42 wks, mortality was 55%. Thirty four infants (14%) were > 42 wks, 9 (27%) died. Sixty seven (28%) were ⩽ 37 wks, only 3 died (4%) & they had CA/CHD. PD other than MAS occurred in 54/67 (80%). None of the ≤37 wks. who had PD and were born by elective c-section or induction had prenatal lung maturity studies. Morbidity and mortality remains high in this group of infants. Prevention of postmaturity and better intrapartum management should significantly decrease the number of deaths. Accurate assessment of lung maturity and gestational age, in order to avoid iatrogenic prematurity, will decrease the number of infants ⩾ 2500 gms requiring neonatal intensive care.

The effect of Tz in treatment of PFC was evaluated in 14 neonates (gestational age (GA) ≤ 34 weeks, n=6) receiving maximal assisted ventilation. Intravenous Tz was administered as a loading dose of 1 to 2 mg/kg followed by a continuous intravenous infusion of 1 mg/kg/hr. The dose was increased up to 4 mg/kg/hr based on the patients clinical response. Clinical status, laboratory parameters and Tz serum concentrations were monitored throughout therapy. A positive response to Tz was observed in 70% of the patients. A curvilinear relationship was noted between Tz serum concentrations and PaO2/FiO2 ratio. The response to tolazoline was dependent on GA, serum concentration and arterial pH. A significant difference (p 34 weeks and ≤ 34 weeks GA. In neonates > 34 weeks, positive therapeutic response was observed with arterial pH > 7.45 and Tz serum concentrations of 2-4 μg/ml. Neonates of ≤ 34 weeks GA, a positive therapeutic response was seen at serum concentration of 4.4 - 7.7 μg/ml and an arterial pH of 7.31 - 7.44. Systemic hypotension and GI bleeding were observed in 28.6% of the patients. This was related to high serum concentrations and arterial pH < 7.30. The rational use of Tz for the treatment of PFC requires careful monitoring of respiratory status, pH, blood pressure and serum Tz concentration.

Since there is a relationship between prostaglandin metabolism, Se and glutathione peroxidase (GSH-PX), and diabetics are reported to have low levels of Se and prostacyclin, we have wondered whether some of the problems which occur in IDM (cardiomyopathy and persistent fetal circulation) might be related to Se deficiency. We studied Se in whole blood of IDM (within 1-2 days after birth) and their mothers. The IDM had a birth weight (mean±SD) of 3857±1075 gm, gestational age of 37.8±1.5 wks, 1 and 5 minute Apgar scores of 7.3±2.7 and 8.8±1.7 respectively. Correlation between the maternal and infants' blood Se concentration in IDM group was not significant. Comparison between IDM, normal full term newborn (NB) infants, and the mother of IDM follows: This preliminary study did not find unusually low Se in whole blood of IDM or their mothers, but because of the potential importance of Se in IDM, a larger study is still indicated.

Sir .—Sell et al 1 recently reported on the neurodevelopmental outcome of infants suspected of having persistent fetal circulation (PFC) in the newborn period. The significant number of infants noted to have a hearing loss is an important finding. The authors' findings, however, may not be applicable to all infants with persistent pulmonary hypertension of the newborn (PPHN) because of a number of apparent flaws in the study. First, the authors give the impression that all infants with PPHN born during the study period were included in their population. If this is true, how do the authors account for a mortality rate of 0% over seven years? The reported mortality rate for PPHN during the same period was 50% to 78%. 2,3 Next, less than half of the study population had PPHN as defined by Fox and Duara. 4 The authors define PFC or PPHN in the introduction as hypoxemia

Because of persistent high mortality of patients(pts)with congenital diaphragmatic hernia (CDH), symptomatic within hours of birth, from persistent fetal circulation(PFC); we designed a protocol to assess the physiologic effects of general anesthesia(GA) after repair of CDH. In 12 months 10 pts, presenting at 150 torr after surgery 6(86%)survived; overall survival 60%. All 7pts who entered the 'honeymoon' period had a low pulmonary vascular resistance(PVR); 5 later developed suprasystemic PVR and PFC. In all but one, who died at 14 days of age, the PVR was controlled by fentanyl and ventilatory adjustments without the use of vasodilators. The Qs/Qt was initially greater than 50% in all but 2pts decreasing to less than 15% by 48hrs in all survivors. While closely monitoring the PA pressure and PaO2 the pts were gradually weaned from pressure ventilation and oxygen. These preliminary data suggest that those pts with CDH who enter the 'honeymoon' period after repair have sufficient lung tissue to survive. Prolonged GA with fentanyl may blunt the reactivity of the PVR allowing postnatal maturation of the pulmonary circulation, obviating the need for potentially dangerous vasodilators. When coupled with careful monitoring these techniques may improve the survival of pts with CDH.

87 IS THERE AN ANATOMICAL BASIS FOR SOME CASES OF SO CALLED “PERSISTENT FETAL CIRCULATION”?

Effective mechanical ventilation of infants with PFC often requires simultaneous administration of P to improve lung compliance and decrease the risk of air leaks. During the past year, we have studied 18 infants (Pr)(BW @ 3222.8 gm; GA @ 38.4 wks) using CVP catheters and volume replacement (VOL), either as colloid or PRBCs, to maintain CVP>5 torr, Uo> 2 cc/kg/hr and Usg < 1.010 while requiring HV & P for PFC. The controls (C) consisted of 16 infants studied retrospectively (BW @ 3018.8 gm; GA @ 39.3 wks) who required HV & P for PFC. 16/18 Pr survived (88.9%) while only 8/16 C survived (50%, p

Subxiphoid two dimensional echocardiograms (echos) were examined in infants (

RRV has been used to reduce PaCO2 in infants with persistent fetal circulation. RRV produces AO in the rabbit lung (time constant (τ) similar to infants). We hypothesized that AO could be reduced if the PEEP in the trachea (PEEPT) was controlled during RRV. We studied 10 rabbits measuring tracheal airway pressure, functional residual capacity (FRC) PaO2 and PaCO2 at ventilator (Baby Bird®) rates of 30, 60, 90 and 120 BPM white: 1) controlling ventilator PEEP (PEEPV) at 2 cm H2O then 2) controlling PEEPT at 2 cm H2O. Peak inspiratory pressure was held constant (15 cm H2O) as was inspiratory:expiratory time (1:2) at rates of 60, 90 ahd 120 BPM. To control PEEPT we lowered PEEPv to 1.2, 1.1 and 0.5 cm H2O. As rates were increased, controlling PEEPT resulted in significant decreases in mean airway pressure (Paw) (by 0.0±.0(SE), 0.4±.1, 0.5±.1 and 1.0±.2 cm H2O) and FRC (14±1, 15±1, 17±2, 21±2 ml/kg when PEEPV was 2 cm H2O vs. 14±1, 14±1, 15±1, 16±2 ml/kg when PEEPT was 2 cm H2O) (p

Efficient ventilation relieves pulmonary vasospasm in persistent fetal circulation (PFC). Evidence on surfactant deficiency

Infants at risk for development of PFC may require hyperventilation (HV) & muscle relaxation (MR) to improve lung compliance and oxygenation. During the past 4 months (6-10/83), we have identified a separate population of infants who may present initially with symptoms indistinguishable from those infants who develop PFC but who respond to hyperoxia (FIO2 = 1.00) and can be successfully managed with oxygen without the need for HV and MR. We studied 12 infants (BW @ 3997.5, GA @ 40.1), 8 with evidence of perinatal aspiration, and compared their initial response to oxygen with 16 infants (BW @ 3102.5 gm, GA @ 38 wk) who required HV & MR for therapy of PFC this past year. No significant differences were noted in PaO2 response in FIO2 = 0.21 or 0.40 among TPVL or PFC infants. A significant rise in PaO2 was observed among TPVL infants, but not PFC infants, when exposed to FIO2 = 1.00 (250.7 torr vs 86.0 torr, p

Factors possibly associated with increased use of drug exposure in a NICU were evaluated prospectively in all neonates admitted to NICU since Feb 1977. Demographic, clinical and laboratory data on all babies (Bb) were recorded by a physician/nurse monitor team and stored in the computer. Analyses of data from the first 461 neonates (bt wgt range 734-4850 g, gestational age (GA) 24-43 wks) show that 128 different drugs were used. 76.1% of babies received 1 to 35 drugs (excluding routine Vit K and AgNO3) with a mean exposure of 4.6/Bb. Babies with GA 32 wks (9.7 vs 3.4 drugs/Bb). GA and bt wgt were inversely related with drug exposure (number of drugs/Bb). Drug exposure was greater in disease states more commonly associated with prematurity; 14.2 drugs/Bb in PDA, 16.8 in necrotizing enterocolitis, 14.5 in persistent fetal circulation, 12.5 in renal failure, 13.1 in liver disease. 17 different antimicrobials were used in 47.7% of Bb, diuretics in 17.4%, cardiovascular drugs in 9.8%, steroids in 4.3% and sedatives and narcotics for palliation in 13.0%. Mean bt wgts and GA were significantly lower in babies who received antimicrobials, diuretics, and methylxanthines. Data underscore the necessity of requisite pharmacologic studies in the low bt wgt infants who are at greater risk of drug exposure.