Tolazoline therapy for persistent pulmonary hypertension after congenital diaphragmatic hernia repair

Clinical guidelines for the treatment of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a birth defect of the diaphragm in which abdominal organs herniate through the defect into the thoracic cavity. The main pathophysiology is respiratory distress and persistent pulmonary hypertension because of pulmonary hypoplasia caused by compression of the elevated organs. Recent progress in prenatal diagnosis and postnatal care has led to an increase in the survival rate of patients with CDH. However, some survivors experience mid- and long-term disabilities and complications requiring treatment and follow-up. In recent years, the establishment of clinical practice guidelines has been promoted in various medical fields to offer optimal medical care, with the goal of improvement of the disease' outcomes, thereby reducing medical costs, etc. Thus, to provide adequate medical care through standardization of treatment and elimination of disparities in clinical management, and to improve the survival rate and mid- and long-term prognosis of patients with CDH, we present here the clinical practice guidelines for postnatal management of CDH. These are based on the principles of evidence-based medicine using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. The recommendations are based on evidence and were determined after considering the balance among benefits and harm, patient and society preferences, and medical resources available for postnatal CDH treatment.

Efficacy of protocolized management for congenital diaphragmatic hernia. a review of 100 cases

A review of 100 consecutive cases of congenital diaphragmatic hernia (CDH) treated at our institute focusing on the efficacy of protocolized management (PM) was conducted. Of the 100 cases, 14 who became symptomatic more than 24 h after birth, and seven with fatal anomalies (four cardiac and three chromosomal) were excluded, leaving 79 subjects for this study. Of these, 41 were diagnosed prenatally (PD). Subjects were divided into four groups. Group I: No PD, no PM (n = 34), Group II: No PD, PM (n = 4), Group III: PD, no PM (n = 21), and Group IV: PD, PM (n = 20). PM includes criteria for planned delivery, use of high frequency oxygenation, nitric oxide, echocardiography (EC), and a medication schedule. Overall survival rates for Groups I, II, III, and IV were 73.5% (25/34), 75% (3/4), 38.1% (8/21), and 70.0% (14/20), respectively. Survival rates were higher when PM was used: 70.8% (Groups II, IV) versus 60.0% (Groups I, III). Survival rates were significantly lower if diagnosed prenatally (PD+): 53.7% (Groups III, IV) versus 73.7% (Groups I, II) (P < 0.01). However, in PD+ groups, survival was significantly higher if PM was used (P < 0.05). PM significantly reduced length of hospital stay (35.5 vs. 52.0 days: P < 0.05). EC was found to be a predictor for survival while post-ductal AaDO(2) was not. In 17 cases with cardiac anomalies, PM did not affect survival. Our study suggests that use of PM for prenatally diagnosed CDH cases is associated with improved outcome, although the components of PM need to be tested in prospective trials to determine their true value.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a lethal human birth defect. Hypoplastic lung development is the leading contributor to its 30-50% mortality rate. Efforts to improve survival have focused on fetal surgery, advances in intensive care and elective delivery at specialist centres following in utero diagnosis. The impact of abnormal lung development on affected infants has stimulated research into the developmental biology of CDH. Traditionally lung hypoplasia has been viewed as a secondary consequence of in utero compression of the fetal lung. Experimental evidence is emerging for a primary defect in lung development in CDH. Culture systems are providing research tools for the study of lung hypoplasia and the investigation of the role of growth factors and signalling pathways. Similarities between the lungs of premature newborns and infants with CDH may indicate a role for antenatal corticosteroids. Further advances in postnatal therapy including permissive hypercapnia and liquid ventilation hold promise. Improvements in our basic scientific understanding of lung development may hold the key to future developments in CDH care.

Does extracorporeal membrane oxygenation benefit neonates with congenital diaphragmatic hernia? Application of a predictive equation

The overall survival of neonates with congenital diaphragmatic hernia (CDH) remains poor despite the advent of extracorporeal membrane oxygenation (ECMO). Attempts at accurately predicting survival have been largely unsuccessful. The purpose of this study was twofold: (1) to identify independent predictors of survival from a cohort of CDH neonates treated at the authors' institution when ECMO was not available and combine them to form a predictive equation, and (2) to apply the equation prospectively in a cohort of CDH neonates, treated at the same institution when ECMO was available, to determine whether ECMO improves outcome. From the clinical data of 62 CDH neonates treated at the authors' center by the same team of university neonatologists and pediatric surgeons between 1983 and 1993 (before ECMO availability), 15 preoperative and seven operative variables were selected as potential independent predictors. When subjected to multivariate, stepwise logistic regression analysis, four variables were identified as statistically significant (P < .05), independent predictors of survival: (1) ventilatory index (VI), (2) best preoperative PaCO2, (3) birth weight (BW), and (4) Apgar score at 5 minutes. When combined via logistic regression analysis, the following predictive equation was formulated: P (probability of survival to discharge) = [1 + e(x)]-1 where x = 4.9 - 0.68 (Apgar) - 0.0032 (BW) + 0.0063 (VI) + 0.063 (PaCO2). Applying a standard cut-off rate of survival at less than 20%, the equation yielded a sensitivity of 94% and a specificity of 82% in identifying the correct outcome of patients treated with conventional ventilatory management. The overall survival rate was 66%. Since the availability of ECMO at the center, 32 CDH neonates were treated using the same conventional ventilatory treatment and surgical repair by the same university staff. The overall survival rate was 69%. The predictive equation was applied prospectively to all neonates to determine predicted outcome, but was not used to decide the treatment method. Eighteen neonates received conventional therapy alone; 16 of 18 survived (89%). Fifteen of the 16 patients who survived had their outcomes predicted correctly (94%). Fourteen neonates did not respond to conventional therapy and required ECMO; 6 of 14 survived (43%). Six of the eight patients predicted to survive, lived (75%). All six patients predicted to die, died despite the addition of ECMO therapy (100%). The mean hospital cost, per ECMO patient who died, was $277,264.75 +/- $59,500.71 (SE). An odds ratio analysis, using the four independent predictors to standardize for degree of illness, was performed to assess the risk associated with adding ECMO therapy. The result was 1.25 (P = 0.75). Although the cohort was not large enough to eliminate significant beta error, the data strongly suggested no advantage of ECMO. At this center, absolute survival rates for neonates with CDH have not been significantly altered since ECMO has become available (66% v 69%). The authors conclude that the predictive equation remains an accurate measurement of survival at their center even when ECMO is used as a salvage therapy. The method of creating a predictive equation may be applied at any institution to determine the potential outcome of CDH neonates and assess the effect of ECMO, or other salvage therapies, on survival rates.

Dual vasoactive effects of tolazoline on rabbit pulmonary arteries

OBJECTIVES

To determine the vasoactive effects of tolazoline on isolated rabbit pulmonary arteries.

DESIGN

Prospective, in vitro, randomized, controlled trial.

SETTING

Experimental laboratory in a university-affiliated hospital.

PARTICIPANTS

New Zealand White Rabbits.

INTERVENTIONS

The pulmonary artery rings were obtained via thoracotomy. Their vasoactive responses were assessed in the presence and absence of intact endothelium and with or without precontraction by norepinephrine (NE, 3 x 10(-6) M) or potassium chloride (KCl, 3 x 10(-2) M). Using a tissue bath preparation, cumulative concentration response curves of tolazoline were obtained at different concentrations (10(-9) to 10(-4) M) after a period of stabilization.

MEASUREMENTS AND MAIN RESULTS

Tolazoline caused vasoconstriction of isolated pulmonary arteries without any pretreatment. The magnitude of the constriction was dose related and reached 300 g/g wet tissue at a concentration of 10(-4) M. On KCl-precontracted pulmonary arteries, tolazoline caused significant dose-related vasoconstriction. On the NE-precontracted vessel rings, it elicited significant dose-dependent vasodilation up to 60% relaxation at 10(-5) M. All the above effects were endothelium independent.

CONCLUSIONS

Tolazoline has dual endothelium-independent vasoactive effects, causing vasoconstriction on isolated rabbit pulmonary arteries, either untreated or precontracted with KCl, and vasodilation on those precontracted with NE. Tolazoline may act as a competitive alpha-adrenoceptor blocking agent.

Respiratory insufficiency as a cause of neonatal death (with aspects on the potential need for ECMO treatment)

In order to identify children with fatal outcome in a neonatal intensive care unit in which only outborns are admitted, a retrospective study over a 10-year period was undertaken. The study was limited to respiratory disorders. The aim of the study was to identify lethal risk factors and thereby the need for improving therapeutic tools. Diagnoses, perinatal history, ventilator settings, blood gases, medical treatment, X-ray findings, head ultrasounds, echocardiograms, laboratory tests, surgical procedures and autopsy findings were evaluated. Severe respiratory insufficiency requiring mechanical ventilation was found in 777 patients and of these babies, 207 (27%) died while still on the ventilator. Fifty-eight patients were excluded for various reasons and thus 149 patients were included in the study. It is concluded that the mortality rate from respiratory insufficiency in the material studied was consistently high over the 10-year period. New therapeutic modalities, one of which is ECMO, are offered nowadays in clinical practice and may improve mortality and morbidity rates.

Persistent pulmonary arterial hypertension of the newborn

Persistent pulmonary hypertension of the newborn (PPHN) characterised by right to left shunting with intense cyanosis is difficult to manage, and in the best of centres carries a 40-60 percent mortality. We report our one year's experience of managing six neonates with PPHN. There were 5 males and 1 female with mean birth weight of 2.59 +/- 0.487 kg and gestation period 39 +/- 2.0 wks and 1 minute Apgar score 2.8 +/- 2.1. Four to six babies were born by cesarean section and 3-6 babies had aspiration pneumonia. All babies presented within 12 hours of age (mean 5.08 +/- 5 hrs) with intense cyanosis and respiratory distress. Diagnosis were confirmed in all by (a) hyperoxia test, (b) simultaneous determination of preductal and postductal paO2 (c) contrast echocardiography and (d) hyperoxia-hyperventilation test. Babies were managed with hyperventilation using mean ventilatory rates of 100 +/- 45 per minute, an inspired oxygen concentration of 100%, peak inspiratory pressures 27 +/- 9 cm of H2O, and expiratory pressures 5 +/- 1.6 cms of H2O, and mean air way pressures of 10.4 +/- 2.7 cms H2O. Alkali therapy was used in 3 of the six babies whereas low dose dopamine was infused in all six babies. Inspite of aggressive ventilatory therapy, only 3 out of 6 babies could be salvaged.

Delayed surgical repair and ECMO improves survival in congenital diaphragmatic hernia

One hundred ten infants with congenital diaphragmatic hernia (CDH) developed life-threatening respiratory distress in the first 6 hours of life. Associated anomalies were present in 33%. Twenty-eight of 65 infants (43%) treated before 1987 (pre-extracorporeal membrane oxygenation [ECMO] era) survived after immediate CDH repair, and mechanical ventilation with or without pharmacologic support. Only two of 16 (12.5%) infants requiring a prosthetic diaphragmatic patch survived. Since 1987, 31 of 46 (67.4%) infants with birth weight, gestational age, and severity of illness similar to the pre-1987 group survived. All patients were immediately intubated and ventilated. Seven (four with lethal chromosomal anomalies) infants died before treatment, and 30 stabilized (partial pressure of carbon dioxide [PCO2] < 50; partial pressure of oxygen [PO2] > 100; pH > 7.3) and underwent delayed CDH repair at 5 to 72 hours. Fifteen did well on conventional support and survived. Fifteen infants deteriorated after operation: 11 were placed on ECMO with eight survivors, and four infants were not considered ECMO candidates. Nine babies failed to stabilize initially and were placed on ECMO before CDH repair (alveolar-arterial gradient > 600 and oxygenation index > 40), and seven survived. The overall survival rate was 80% at 3 months in this ECMO-treated group. Early mortality was due to inability to wean from ECMO (one), intracranial hemorrhage (one), liver injury (one), and pulmonary hypoplasia (one). Nine of 11 babies requiring a prosthetic patch in the post-1987 ECMO group survived (81.8%). There were three late post-ECMO deaths (3 to 18 months) of right heart failure (two) and sepsis (one). Symptomatic gastroesophageal reflux occurred in nine cases, six requiring a fundoplication in the bypass babies. Recurrent diaphragmatic hernia occurred in nine cases (five ECMO). The overall survival rate was significantly improved in the delayed repair/ECMO group (67% versus 43%; p < 0.05) and was most noticeable in infants requiring a prosthetic diaphragm (81.2% versus 12.5%; p < 0.005). These data indicate that early stabilization, delayed repair, and ECMO improve survival in high-risk CDH. Early deaths are related to pulmonary hypertension and can be reversed by ECMO.

The impact of extracorporeal membrane support in the treatment of congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia (CDH) treated by immediate surgical intervention and conventional ventilatory support have an overall poor survival. The potential of extracorporeal membrane oxygenation (ECMO) therapy to improve survival of infants with CDH remains controversial. Comparison was made in a single institution's pre-ECMO and post-ECMO survival statistics to establish efficacy of extracorporeal support for persistent pulmonary hypertension (PPH). This study was accomplished by stratifying patients by an oxygen index (OI). Sixty-eight patients were treated for CDH from 1977 to 1986 without ECMO. Fifty-eight patients underwent repair of CDH within the first 24 hours of life. Data could be retrieved for calculation of the OI in 46 patients. Nineteen patients developed an OI of 40 or greater; one survived (5%). Three of 27 patients with an OI less than 40 died (OIs = 34, 38, and 38). Thirty-one patients were treated from 1987 to 1989 and none were excluded from ECMO based on a minimum PO2. Fifteen had an OI less than 40 (range, 1 to 38), were treated conventionally, and 13 survived (87%). Sixteen patients had an OI greater than 40 and 13 qualified for ECMO. Nine of 13 survived (69%). Comparing pre-ECMO and post-ECMO survival for infants with an OI of 40 or greater (5% v 69%), there is a significant improvement in survival when ECMO is used (P less than .001). ECMO support offers a strong adjunct in management of neonates with CDH who develop PPH.

Pulmonary hypertension in lambs with congenital diaphragmatic hernia: vasodilator prostaglandins, isoprenaline, and tolazoline

After antenatal induction of diaphragmatic hernias in fetal lambs, prostaglandins D2, E1, and I2 were compared to tolazoline, or isoprenaline, for the treatment of pulmonary hypertension. When rendered hypoxic, these, and normal lambs, showed an increase in pulmonary artery pressure, a decrease in systemic pressure, and a decrease in pulmonary blood flow. All of the drugs altered that response, but to different degrees. None of the drugs tested was consistently successful in reversing the adverse affects of hypoxia, but prostaglandin D2 came closest to the ideal vasodilator, decreasing the pulmonary artery pressure in all seven hypoxic lambs having a diaphragmatic hernia. There was a concomitant increase in pulmonary blood flow in six; in the remaining lamb the decrease in blood flow induced by the hypoxia was arrested. At the same time, there was an increase in systemic artery pressure in three, the decrease was arrested in two, but the decrease continued in the other two. Isoprenaline was a more effective drug than tolazoline, producing an increase in pulmonary blood flow in five of the seven lambs, with minor decreases in systemic pressure in five. Tolazoline improved blood flow in three of six lambs (not all lambs survived the full study), with a marked decrease in systemic pressure in four of them. Prostaglandin D2 seems to be a useful drug for the treatment of patients having diaphragmatic hernias and pulmonary hypertension, and warrants further study. Isoprenaline was the most effective of the readily available drugs tested in this animal model.

Successful gastrorrhaphy on ECMO

From April 1985 to November 1987, over 100 infants were evaluated for extracorporeal membrane oxygenation (ECMO) in the treatment of respiratory failure. Of these infants, 40 underwent ECMO after failure of conventional treatment. Four developed gastroduodenal perforations. One developed a perforation prior to going on ECMO and died after several hours on ECMO, one developed a perforation while being treated conservatively for respiratory failure that never required ECMO, and two developed perforations requiring laparotomy while on ECMO. These two infants constitute the first report of successful gastrorrhaphy in infants while being supported by ECMO and anticoagulation with heparin. Particular measures helpful in the management of these infants included near-total cardiopulmonary bypass, reduction of the activated clotting time to 170 to 200, transverse abdominal incision for exposure, use of electrocautery, appropriate drainage of the operative site, insertion of a gastrostomy for gastric decompression and irrigation, rapid weaning from ECMO as soon as respiratory support could be provided by conventional methods, and the use of massive blood and platelet transfusions. In summary, 33 of 40 infants undergoing ECMO survived. Furthermore, two of the three infants with intestinal perforation who underwent ECMO have survived without significant short-term sequelae, and are 24 and 30 months of age, respectively. Therefore, we believe that despite severe respiratory failure requiring ECMO and anticoagulation with heparin, infants with intestinal perforation can be managed surgically with anticipated survival and good long-term prognosis.

Congenital diaphragmatic hernia: impact of preoperative stabilization. A prospective pilot study in 13 patients

In case of congenital diaphragmatic hernia (CDH), survival generally depends not on prenatal diagnosis, planned delivery, and immediate postnatal operation, but on the gravity of pulmonary hypoplasia and persistent hypertension (PPH). Many vasoactive drugs have become available for lowering PPH, but the mortality rate for CDH still amounts to 40% to 70%. Preoperative stabilization might prevent or at least reduce the risk of PPH. This method was evaluated in a pilot study lasting 15 months and involving 13 patients. All were admitted to the pediatric surgical intensive care unit within six hours of birth, all requiring mechanical ventilation. Continuous suction of the stomach and bowel proved successful in reducing the mediastinal shift. Study parameters were alveolar-arterial oxygenation differences ((A-a)DO2), mean airway pressure (MAP), oxygenation index (OI), and ventilation index (VI), measured on admission and at set times before and after surgery. Eight patients did not survive, but in two cases death was not directly related to CDH. The following conclusions were reached: (1) satisfactory ventilation parameters on admission will remain good during the preoperative stabilization phase and will not be affected by its duration or by subsequent surgery, spelling survival; (2) unsatisfactory ventilation parameters on admission may improve with preoperative stabilization, giving these patients a better chance of survival; and (3) poor ventilation parameters on admission that fail to improve with preoperative stabilization will not improve with surgery or postoperatively, spelling death.

Refractory neonatal hypoxemia: diagnostic evaluation and pharmacologic management

Hypoxemia refractory to oxygen administration and assisted ventilation is found in many clinical conditions and results from a variety of pathophysiologic disorders. Recent clinical and laboratory experience has demonstrated that the choice of therapy for an infant with refractory hypoxemia depends upon identification of the underlying etiologic and pathophysiologic conditions. The ideal therapies for many of these conditions have not yet been defined. We have provided, based on our experience, guidelines for selection of the most appropriate of the currently available therapies for many of these patients.

Congenital diaphragmatic hernia: the prognostic significance of the site of the stomach

Congenital diaphragmatic hernia is associated with a significant mortality, despite intensive treatment. The degree of pulmonary vascular hypoplasia is the main factor affecting mortality. Various features have been considered to determine the prognosis in these infants. In this study a series of 50 consecutive cases of left-sided diaphragmatic hernia has been reviewed. The site of the stomach (abdominal or intrathoracic), demonstrated radiologically and confirmed at operation, has been related to the final outcome (survival or death). An abdominal site is associated with an excellent prognosis (6.2% mortality), while an intrathoracic site is associated with a 58.8% mortality.

Ventilatory predictors of pulmonary hypoplasia in congenital diaphragmatic hernia, confirmed by morphologic assessment

We carried out a prospective study in 66 infants with congenital diaphragmatic hernia within the first 6 hours of life to determine whether outcome is related to the degree of underlying pulmonary hypoplasia, as predicted by preoperative PaCO2, when correlated with an index of ventilation (VI = mean airway pressure X respiratory rate) and confirmed by postmortem analysis of the lung. Those infants with PaCO2 greater than 40 mm Hg before surgery had a 77% mortality; when PaCO2 reduction could be achieved only with VI greater than 1000, the mortality was still greater than 50%. After repair, however, the ability to hyperventilate to PaCO2 less than 40 mm Hg proved to be an important determinant of survival; only one of 31 infants in this group died, whereas only two of 27 infants with PaCO2 greater than 40 mm Hg survived. In 16 infants with PaCO2 greater than 40 mm Hg despite hyperventilation, high-frequency oscillatory ventilation was started. This resulted in a rapid fall in PaCO2, but 14 of the 16 infants had only temporary improvement in oxygenation, and died. In five of the infants who died, alveolar number was assessed by postmortem morphometric analysis; there was a severe reduction to less than 10% of published normal neonatal values. Pulmonary vascular changes of increased muscularization were less remarkable than those observed in infants with persistent pulmonary hypertension. Our findings suggest that the degree of pulmonary hypoplasia (which would not be influenced by surgical repair), rather than the pulmonary vascular abnormality, mainly determines survival. Consideration could therefore be given to an initial nonsurgical approach to congenital diaphragmatic hernia, with the expectation that pulmonary function might improve and pulmonary vascular resistance decrease.

Effect of surgical repair on respiratory mechanics in congenital diaphragmatic hernia

To determine whether surgical repair of congenital diaphragmatic hernia (CHD) results in improvement in respiratory mechanics, we measured respiratory system compliance in nine patients (five survivors and four nonsurvivors) before and after operation. In all nine infants, CHD was diagnosed within 6 hours of life, and surgical repair was through an abdominal approach after a period of stabilization. Measurements were made noninvasively, using the passive expiratory flow-volume technique. In only one of the nine infants did compliance immediately improve after surgical repair, and in another it showed no change. Both of these infants survived, with an uneventful postoperative course. In the remaining seven infants, however, postoperative compliance immediately decreased to 10% to 77% from the preoperative value. The four infants with more than 50% decrease in compliance died with increasing hypoxemia and acidosis. These results suggest that respiratory mechanics in CHD, far from improving, frequently deteriorate as a result of repair of the hernia. The role of urgent surgery in this malformation should be reevaluated.

Congenital diaphragmatic hernia and the management of persistent foetal circulation

Twenty-two cases of diaphragmatic hernia, presenting from 1978 to 1982, were reviewed. Sixteen patients presented before 24 hours of life, of whom nine survived (56%). Six were late presenters who all did well. Seven babies had ten documented episodes of persistent foetal circulation (PFC) occurring as early as three hours postoperatively, although three babies had episodes in their second week. Hyperventilation, with hand bagging, was successful in treating five out of six episodes of PFC (83%), without complication. Tolazoline caused improvement in two out of four episodes of PFC but was associated with significant complications. We recommend early and sometimes persistent use of hyperventilation by hand bagging as a means of managing PFC in diaphragmatic hernia.

Congenital diaphragmatic hernia: a 20 year experience

The records of 253 children with congenital diaphragmatic hernia admitted to The Hospital for Sick Children, Great Ormond Street, between 1961 and 1980 were analysed. The overall mortality of 37 per cent is greater than that reported in the preceding 13 years from the same institution, and showed no improvement over the 20 years. While there was no significant increase in the number of admissions over the study period, the proportion of children who underwent surgery within the first 6 h of life steadily increased from 13 per cent in the first five years to 39 per cent in the last five years. The mortality of this group (65 per cent) did not improve over the study period and this would account for the lack of improvement in the overall survival figures. However, analysis of birth weights, onset and severity of signs and lung weights indicates that the increasing number of early admissions was due to speedier transfer rather than to referral of more severely affected children in the later years.

Congenital diaphragmatic hernia: arterial structural changes and persistent pulmonary hypertension after surgical repair

Some infants with congenital diaphragmatic hernia who die after surgical correction have a transient postoperative period during which systemic oxygenation is adequate (honeymoon period), whereas others have persistent hypoxemia. Using morphometric techniques, we analyzed lung structure, especially the arterial bed, in seven infants who died within 1 week of surgical repair. Three infants comprised the honeymoon group, the PaO2 transiently being greater than 150 mm Hg in the descending aorta (FiO2 1.0); four infants comprised the no-honeymoon group and never had PaO2 greater than 85 mm Hg. All lungs were hypoplastic for age; with one exception, infants in the no-honeymoon group had smaller lungs. Arterial structure in the no-honeymoon group contributed to a greater reduction in pulmonary arterial cross-sectional area. Each infant in the no-honeymoon group had muscularization of intra-acinar arteries and failure of perinatal increase in compliance of small preacinar arteries, features not seen in the honeymoon group or in the normal newborn infant. In addition, compared with the honeymoon group, luminal area of preacinar and intra-acinar arteries in the no-honeymoon group was decreased by reduced external diameter or increased medial thickness. Clinical deterioration in the honeymoon group is based on a vasoconstrictive response of the hypoplastic vascular bed. Persistent hypoxemia in the no-honeymoon group is based on both severity of pulmonary hypoplasia and structural remodeling of the pulmonary arteries.

The relationship between PaCO2 and ventilation parameters in predicting survival in congenital diaphragmatic hernia

Fifty-eight infants with congenital diaphragmatic hernia presenting within the first 6 hours of life, who underwent surgical repair, were analysed prospectively in order to produce a reliable index of severity of disease that would reliably predict eventual outcome. All were treated with paralysis hyperventilation and intravenous (IV) isoproterenol for the first 48 hours. There were 30 survivors and 28 deaths in this series (mortality 48%). Using arterial PCO2 values measured 2 hours after surgical repair and correlating them with an index of mechanical ventilation (mean airway pressure and respiratory rate), we have been able to clearly define two groups of diaphragmatic hernia based on their response to IPPV. The first group, with CO2 retention and severe preductal shunting, was unresponsive to hyperventilation with high rates and pressures; the mortality was 90%. The second group responded well to hyperventilation and demonstrated reversable ductal shunting only. Survival in this group was 97%. Only four patients out of 58 exhibited the "honeymoon period," with a period of stability followed by severe ductal shunting. Arterial CO2 accurately reflects the degree of lung development in this disease and separates those patients with severe pulmonary hypoplasia, where the outcome is invariably fatal, from those with a well-developed contralateral lung where there is excellent potential for survival.

The early evaluation of survivors after extracorporeal membrane oxygenation for neonatal pulmonary failure

Excluding mortality data, there is little information regarding patients' development after extra corporeal membrane oxygenation (ECMO). In six of nine neonates surviving ECMO for predictably fatal pulmonary failure, examination 15 to 21 months afterward showed (1) physical growth and development, normal in six; (2) chest x-ray, normal pulmonary parenchyma; (3) average arterial blood gases, PO2 80, Pco2 35, pH 7.35; (4) echocardiogram, normal, without evidence of pulmonary hypertension; (5) cerebrovascular dopplers, normal ophthalmic artery flow in five patients, retrograde in one; (6) CT scan, EEG, neurologic survey, normal in five, cerebral atrophy in one patient who had an air embolus during decannulation; (7) psychologic examination, normal in all. This early evaluation of ECMO survivors should encourage its further application in those newborns who would otherwise die.

The decreasing incidence of pneumothorax and improving survival of infants with congenital diaphragmatic hernia

In the 6-year period between 1977 and 1982 inclusive, 75 newborn infants with congenital diaphragmatic hernia of Bochdelek underwent corrective surgery during the first 24 hours of life. A total of 40 infants (53%) survived. Beginning in January 1980, a standardized approach to care including early use of mechanical ventilation and paralysis with pancuronium as well as dopamine use prior to any Priscoline infusion, was instituted. To determine whether these approaches improved outcome, term infants without malformations from the years 1977 to 1979 were compared with a similar group treated after institution of standardized care between 1980 and 1982 inclusive. The infants were comparable in all respects, but survival improved from 45% to 82% between the two periods (P less than 0.03). There was an associated decrease in the incidence of pneumothorax (45% in first period; 14% in second period) paralleled by a concomitant increase in pancuronium use (18% and 85%, respectively). Although factors responsible for the improved survival are multifactorial these data indicate the detrimental effect of pneumothorax on outcome and the beneficial effect of a standardized approach to care using conventional intensive care techniques.

A preoperative x-ray scoring system for risk assessment of newborns with congenital diaphragmatic hernia

The survival rate for newborn infants with congenital diaphragmatic hernia (CDH) is about 50%. The preoperative x-rays of 34 babies with CDH, presenting during the first 12 hours of life were reviewed to determine whether or not the 16 survivors (47%) might be identified. A scoring system using five roentgen findings having a significant correlation with survival (side of diaphragmatic hernia, location of stomach, presence of pneumothorax, relative volume of aerated ipsilateral and contralateral lung) were summed to obtain a total x-ray score. Cumulative scores ranged from 2 to 9 with 4 of 16 survivors (25%) and 16 of 18 (89%) non-survivors scoring above 6. Twelve of 16 (75%) survivors and 2 of 18 non-survivors (11%) (P less than 0.005), scored 6 or less. Individual x-ray findings were less specific in predicting outcome than the total score. Careful examination of the preoperative chest x-ray may give the surgeon an additional method for predicting outcome following repair of CDH during the first 12 hours of life.

Persistent pulmonary hypertension in the neonate: diagnosis and management

PPHN should be recognized as a clinical condition associated with a number of pulmonary and systemic diseases. Present therapy has resulted in increased survival, but the aggressive methods required to produce improvement necessitate a clear understanding of the underlying pathophysiology in order to minimize sequelae.

Postoperative fetal circulation: POFC

Active pulmonary vasoconstriction and subsequent right-to-left atrial and/or ductal shunting of venous blood may influence the course of many neonatal cardiorespiratory disorders. The term "persistent fetal circulation" has been applied to these infants. This report concerns the late occurrence of fetal circulation after major intraabdominal operative procedures in two neonates. The first patient was a full-term, 3.6-kg infant with a covered, large liver-containing omphalocele. Cyanosis, hypoxia, and a right-to-left shunt were present at birth, but were improved by 24 hr of life. Primary repair was delayed for 6 days, in the belief that fetal circulation was unlikely to recur. On day 7, primary fascial closure of the omphalocele was followed by severe hypoxia secondary to right-to-left shunt, documented to be due to postoperative fetal circulation (POFC). The second was a 1600-g premature infant who was well until noted to be lethargic on the fourth day of life. Radiologic findings of pneumoperitoneum led to laparotomy and closure of a spontaneous gastric perforation. Twenty-four hours later the patient developed severe hypoxia and a right-to-left shunt at the atrial level was documented with contrast echocardiogram, again supporting the diagnosis of POFC. Each patient survived and has a normal heart. Both patients responded to hyperventilation and/or tolazoline therapy. Contrast echocardiography was a helpful, noninvasive means of establishing the diagnosis. This diagnosis should be considered in postoperative neonates after more common cardiac and pulmonary causes of hypoxia are excluded.

Clinical use of an extracorporeal membrane oxygenator in neonatal pulmonary failure

Pulmonary failure is the most frequent cause of mortality in newborns, accounting for 15,000 deaths yearly. It may be the result of the respiratory distress syndrome (RDS), meconium aspiration syndrome (MAS), or persistent fetal circulation (PFC), including infants with congenital diaphragmatic hernia (CDH). Early identification of patients with predictably fatal but potentially reversible respiratory failure refractory to conventional management protocols would permit orderly application of extracorporeal membrane oxygenation (ECMO) as a final resuscitative measure. Eight neonates with severe pulmonary failure manifested by A-a DO2 of greater than 620 torr for greater than 12 hr, persistent cardiovascular instability, and relentless progression of acidosis and hypoxemia were predicted to have a 100% mortality in spite of maximal medical therapy. Four patients presented with MAS and 4 others had PFC, including 2 with CDH. All were supported with ECMO using the internal jugular vein and common carotid artery for access to the right atrium and aortic arch. Following support for 77-313 hr, 6 were successfully weaned from ECMO and then from the ventilator. In these few patients the use of extracorporeal membrane oxygenation after exhaustion of standard therapy was accomplished safely and successfully without untoward short-term sequelae. Extracorporeal ventilatory support may purchase the critical time necessary for resolution of the underlying parenchymal disease, including the pulmonary hypertension associated with CDH.