A new approach to congenital posterolateral diaphragmatic hernia

Honeymoon Period in Newborn Rats With CDH Is Associated With Changes in the VEGF Signaling Pathway

Background: Patients with congenital diaphragmatic hernia (CDH) have a short postnatal period of ventilatory stability called the honeymoon period, after which changes in pulmonary vascular reactivity result in pulmonary hypertension. However, the mechanisms involved are still unknown. The aim of this study was to evaluate mechanical ventilation's effect in the honeymoon period on VEGF, VEGFR-1/2 and eNOS expression on experimental CDH in rats. Materials and Methods: Neonates whose mothers were not exposed to nitrofen formed the control groups (C) and neonates with left-sided defects formed the CDH groups (CDH). Both were subdivided into non-ventilated and ventilated for 30, 60, and 90 min (n = 7 each). The left lungs (n = 4) were evaluated by immunohistochemistry of the pulmonary vasculature (media wall thickness), VEGF, VEGFR-1/2 and eNOS. Western blotting (n = 3) was performed to quantify the expression of VEGF, VEGFR-1/2 and eNOS. Results: CDH had lower biometric parameters than C. Regarding the pulmonary vasculature, C showed a reduction in media wall thickness with ventilation, while CDH presented reduction with 30 min and an increase with the progression of the ventilatory time (honeymoon period). CDH and C groups showed different patterns of VEGF, VEGFR-1/2 and eNOS expressions. The receptors and eNOS findings were significant by immunohistochemistry but not by western blotting, while VEGF was significant by western blotting but not by immunohistochemistry. Conclusion: VEGF, its receptors and eNOS were altered in CDH after mechanical ventilation. These results suggest that the VEGF-NO pathway plays an important role in the honeymoon period of experimental CDH.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Modulating effect of a selective endothelin A receptor antagonist on pulmonary endothelin system protein expression in experimental diaphragmatic hernia

BACKGROUND/PURPOSE

Previously, we reported that perinatal administration of atrasentan, a selective endothelin A receptor (ETA) antagonist, provided a beneficial effect on the cardiopulmonary profile under short-term conditions in newborn lambs with surgically induced congenital diaphragmatic hernia (CDH). We hypothesized that changes in the hemodynamic profile that we observed at birth in treated animals could be influenced by pulmonary modulation of the endothelin (ET) system.

METHODS

The effect of atrasentan on protein expression levels of ETs and ET receptors (ETA and ETB receptor) was investigated by immunohistochemistry in lung tissues of untreated control (n = 3), treated control (n = 6), untreated CDH (n = 6), and treated CDH newborn lambs (n = 8).

RESULTS

Right lung tissue of treated control lambs showed significantly higher ETA protein expression levels in both vascular adventitia and airway epithelia when compared with that of untreated control lambs (P < .05). In contrast, protein expression levels of ETA and ETB receptor were significantly lower in the vascular smooth muscle cells among other tissue subcompartments of the right lung of treated CDH newborn lambs vs CDH lambs (P < .02 and P = .005, respectively).

CONCLUSIONS

We speculate that rapid pulmonary modulation of ET system protein expression levels by atrasentan results from an indirect effect possibly dependent on ventilation and/or perfusion. In CDH groups, this could contribute to the beneficial effect of the treatment.

Twenty Years of Progress in Congenital Diaphragmatic Hernia at the University of Florida

Over the past 20 years the clinical paradigms underlying the care of children with congenital diaphragmatic hernia (CDH) have undergone profound changes. The purpose of this work is to provide an historic review of research and clinical studies related to CDH at the University of Florida (UF) and Shands Children's Hospital during the chairmanship of Edward M. Copeland, III, M.D. and to present our current clinical results. During Dr Copeland's tenure survival for newborns symptomatic with CDH treated at UF/Shands Children's Hospital has improved from less than 20 per cent to 85 per cent. Clinical observations have suggested and research studies at UF using a fetal lamb model have confirmed that fetal distress can occur late in gestation, which may predispose infants with CDH to pulmonary hypertension. However, our patient experience has confirmed that the most significant cause of mortality in human infants is not pulmonary hypertension but iatrogenic injury to their hypoplastic lungs. Strict avoidance of barotrauma in these babies has been the most important clinical advance during these two decades. Significant clinical and research problems remain including defining optimal prenatal care, management of complications during the first few weeks of life, and development of strategies to accelerate lung growth. Dramatic improvements in survival have resulted in children who manifest a number of clinical problems that were not evident when most of these patients died early in infancy. Our experience at Shand's Children's Hospital/UF indicates that feeding problems, respiratory infections, and management of subtle or overt neurologic complications may become major issues for some of these survivors and their families.

Effect of prenatal glucocorticoids and postnatal nitric oxide inhalation on survival of newborn rats with nitrofen-induced congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Pulmonary hypertension and pulmonary hypoplasia account for the high mortality rate associated with congenital diaphragmatic hernia (CDH). In animal models of CDH, postnatal nitric oxide (NO) inhalation resulted in significantly better survival rates and antenatal glucocorticoid administration in improved lung compliance. The objective of this study was to evaluate the combined effect of prenatal glucocorticoid administration and postnatal NO inhalation on the survival rate of newborn rats with nitrofen-induced CDH.

METHODS

Right-sided CDH was induced by maternal administration of a single oral dose (100 mg, intraperitoneally) of nitrofen on day 11.5 of pregnancy. Dexamethasone (DEX, 0.25 mg/kg) was given in groups III and IV by maternal intraperitoneal injection on day 18.5 and 19.5 of pregnancy. Control animals (groups I and II) received vehicle alone. After spontaneous delivery, the newborn animals were exposed to either NO (80 ppm; groups II and IV) or room air (groups I and III). Vitality (Rat-Score), sO(2) and survival were monitored continuously for 12 hours until animals were killed. Hernia size was estimated as percentage of total thoracic content.

RESULTS

Right-sided CDH was observed in 392 of 491 newborn rats (81%). Animals with large hernias (>50%) died within 4 hours after birth, irrespective of treatment. Hernias with less than 50% of the thoracic volume were considered clinically relevant hernias. In this category, 12.5% of animals without treatment (group I) survived compared with 63.6% after NO treatment alone (group II; P <.01). Survival rate after DEX treatment alone (group III) was 69.4% (group III v I; P <.01). In group IV (DEX and NO) 95.2% of the animals survived (group IV v I; P <.001). In contrast to DEX alone, NO administration resulted in significantly better sO(2)(group II and IV) compared with group I (P <.05).

CONCLUSION

Combination of prenatal maternal glucocorticoids and postnatal NO inhalation significantly improved survival rate of newborn rats with nitrofen-induced CDH.

Effect of ABT-627 (A-147627), a potent selective ET(A) receptor antagonist, on the cardiopulmonary profile of newborn lambs with surgically-induced diaphragmatic hernia

1. Postnatal mortality in isolated congenital diaphragmatic hernia (CDH) is mainly related to the associated pulmonary hypertension (PH) and to right-to-left shunting. 2. Endothelins (ETs) are potent vasoconstrictors and pro-mitogenic peptides. Strong evidences support their participation in CDH and in the etiology of PH via the activation of ET(A) receptors (ET(A)-Rs). 3. Evaluation of the effect of ABT-627, a selective non-peptidic ET(A)-R antagonist, given from -15 to 210 min post-delivery (1 mg kg(-1) bolus +0.01 mg kg(-1) h(-1) infusion, i.v.), was conducted in the lamb model of CDH. 4. Severity of CDH was assessed in comparison to untreated controls (n=5). Untreated CDH lambs (n=7) had a higher mean pulmonary arterial pressure (MPAP; P<0.0001), lower mean blood pressure (MBP; P=0.0004), higher MPAP / MBP ratio (P<0.0001), lower arterial pH (P<0.0001), higher paCO(2) (P<0.0001), lower paO(2) (P<0.0001) and lower post-ductal pulsatile SaO(2) (P<0.0001) than untreated controls. 5. Treated controls (n=7) showed a higher MPAP, lower MBP, higher MPAP/MBP ratio, lower arterial pH, higher paCO(2), lower paO(2), lower post-ductal pulsatile SaO(2) and lower plasmatic ir-ET ratios compared to untreated controls (P<0.0001). 6. Treated CDH lambs (n=8) showed a higher MBP (P<0.0001), lower MPAP / MBP ratio (P<0.0001), higher arterial pH (P<0.0001), lower paCO(2) (P<0.0001), higher paO(2) (P=0.0228), higher post-ductal pulsatile SaO(2) (P=0.0016) and lower plasmatic ir-ET ratios (P=0.0247) when compared to untreated CDH lambs. 7. These observations revealed that, although acute perinatal treatment with a selective non-peptidic ET(A)-R antagonist had some adverse effects in controls, it attenuated the progressive cardiopulmonary deterioration that occurred after birth in CDH lambs.

Hypoxic pulmonary vasoconstriction is impaired in rats with nitrofen-induced congenital diaphragmatic hernia

BACKGROUND

Pulmonary hypertension and persistent fetal circulation contribute to the high mortality rate associated with congenital diaphragmatic hernia (CDH). Morphological alterations of the pulmonary vasculature in infants with CDH are thought to contribute to exaggerated vasoconstrictor responses to normal vasoconstrictor stimuli. In the pulmonary circulation, hypoxia is a potent vasoconstrictor. Under pathological conditions, hypoxia-induced vasoconstriction may contribute to the development of pulmonary hypertension.

METHODS

The authors have used the nitrofen-induced model of congenital diaphragmatic hernia in rats to investigate the magnitude of the hypoxic vasoconstrictor response. Congenital diaphragmatic hernias were induced in fetal rats by feeding nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) to pregnant Sprague-Dawley rats at midgestation. Hypoxia-induced vasoconstriction was measured in isolated, perfused third-generation pulmonary arterioles from normal rats and from rats with nitrofen-induced CDH.

RESULTS

The hypoxic vasoconstrictor response was significantly blunted in the pulmonary arterioles of fetal rats with nitrofen-induced (2% +/- 1% vasoconstriction), as compared with the responses observed in normal fetal rats (15% +/- 3% vasoconstriction, P = .004).

CONCLUSION

Blunting of the hypoxic pulmonary vasoconstrictor response may contribute to ventilation-perfusion mismatching in infants with CDH.

Pulmonary arterioles from rats with congenital diaphragmatic hernias are hypoplastic but not hyperresponsive

BACKGROUND

Infants born with congenital diaphragmatic hernias (CDH) frequently die as a result of pulmonary hypertension and persistent fetal circulation. The pulmonary vessels of infants with CDH have decreased total cross-sectional area, increased muscle content, and muscularization of intra-acinar arterioles that are normally not muscularized. These structural alterations are believed to result in exaggerated responses to normal vasoconstrictor stimuli.

METHODS

The authors used the nitrofen-induced CDH model in rats to determine whether the vasoconstrictor responses of pulmonary arterioles are exaggerated in this animal model of CDH. The authors compared the responses of isolated third-generation pulmonary arterioles from normal rats and from rats with nitrofen-induced CDH to K+-induced depolarization, phenylephrine, angiotensin II, serotonin, and the thromboxane A2 agonist, U46619.

RESULTS

It was found that the intraluminal diameter of third-generation pulmonary arterioles from CDH rats was significantly less than in controls (129 +/- 5 micron v 152 +/- 9 micron, respectively). In addition, the ratio of wall thickness to vessel internal diameter was increased in the third-generation pulmonary arterioles of rats with nitrofen-induced CDH (0.62 +/- 0.4 v 0.50 +/- 0.5 for controls). Responses to K+-induced depolarization, phenylephrine, angiotensin II, serotonin, and U46619, however, were not different for pulmonary arterioles from control and CDH rats.

CONCLUSION

These data suggest that the structural alterations of the pulmonary vasculature observed in infants with CDH may not cause exaggerated vasoconstrictor responses to normal vasoconstrictor stimuli.

Effect of dexamethasone on endothelial nitric oxide synthase in experimental congenital diaphragmatic hernia

AIMS

To study the effect of prenatal glucocorticoid treatment on endothelial nitric oxide synthase (eNOS) expression in rats with congenital diaphragmatic hernia (CDH).

METHODS

CDH was induced in fetal rats by the maternal administration of nitrofen on day 9.5 of gestation. Dexamethasone was administered on days 18.5 and 19.5 before delivery of the fetuses on days 20.5 and 21.5. Pulmonary eNOS protein expression was studied by western immunoblotting and immunohistochemistry.

RESULTS

On day 20.5, eNOS expression was significantly reduced in CDH pups compared with normal control rats. Dexamethasone treated CDH pups had eNOS concentrations equivalent to those of normal animals. By day 21.5, however, there was no detectable difference in eNOS expression between the experimental groups.

CONCLUSIONS

eNOS is deficient in near term (day 20.5) CDH rats. Dexamethasone restores eNOS expression in these animals to that seen in normal rat lungs. At term, the precise role of eNOS in the pathophysiology of CDH remains uncertain.

Endothelin-1 pulmonary vasoconstriction in rats with diaphragmatic hernia

BACKGROUND

Pulmonary hypertension is an important cause of mortality in infants with congenital diaphragmatic hernia (CDH). Endothelin-1 has been implicated as a mediator of pulmonary hypertension. ET-A receptors are increased in the nitrofen model of CDH in rats. We hypothesized that vasoconstrictor responses to endothelin-1 are increased in pulmonary arterioles of rats with nitrofen-induced CDH.

MATERIALS AND METHODS

CDH was induced in fetal rats by feeding nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) to pregnant rats at midgestation. Third-generation pulmonary arterioles were isolated on the final day of gestation. Arterioles were cannulated and perfused at constant pressure with a physiologic salt solution. Diameters of arterioles from control animals (n = 8), CDH animals (n = 5), and animals exposed to nitrofen but without CDH (n = 4) were measured. Responses to endothelin-1 concentrations of 10(-12) to 10(-8) M were compared by Student's t test.

RESULTS

CDH arterioles constricted more than controls in response to endothelin-1 at concentrations of 10(-11) M (29 +/- 11% vs 5 +/- 3%, P = 0.02) and 10(-10) M (40 +/- 14% vs 9 +/- 6%, P = 0.04). The log concentration of endothelin-1 that induced half-maximal response (ED50) was lower for CDH arterioles than for control arterioles (-10.3 +/- 0.6 vs -9.1 +/- 0.2, P = 0.03). Responses of arterioles from animals exposed to nitrofen but without CDH were not different from controls (P > or = 0.05).

CONCLUSIONS

Exaggerated vasoconstrictor responses to endothelin-1 may contribute to pulmonary hypertension in CDH.

Antenatal glucocorticoid therapy suppresses angiotensin-converting enzyme activity in rats with nitrofen-induced congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Neonates with congenital diaphragmatic hernia (CDH) have a high morbidity and mortality rate caused by pulmonary hypoplasia associated with pulmonary hypertension (PH). In experimental CDH, antenatal glucocorticoid therapy improves surfactant biochemical immaturity, enhances lung compliance, and induces morphological maturation in CDH rats. The effects of steroid therapy on preventing or treating PH in this condition have not been studied. Angiotensin converting enzyme (ACE), which is produced by the vascular endothelium, is implicated in the pathogenesis of pulmonary hypertension. The aim of this study was to evaluate the effect of antenatal glucocorticoid therapy on ACE activity and expression in CDH rat lungs.

METHODS

CDH was induced in fetal rats by the maternal administration of 100 mg nitrofen on day 9.5 of gestation (term, day 22). Dexamethasone (Dex) (0.25 mg/kg) was given by intraperitoneal injection on days 18.5 and 19.5 before delivery of the fetuses by cesarean section on day 21.5. Control animals received olive oil (OO) by gavage and normal saline (NS) as vehicle injection. ACE activity was measured spectrophotometrically in the lungs of rats from four treatment groups: CDH-NS, non-CDH-NS, CDH-Dex, and OO-NS controls. Total lung ACE activity (mU per lung) was significantly lower in CDH-NS (P = .002) and CDH-Dex (P = .004) rats compared with non-CDH-NS and OO-NS controls (9.1 +/- 1.0 and 10.7 +/- 1.3 v 16.2 +/- 1.6 and 15.4 +/- 1.7). When specific ACE activity (mU/mg protein) was derived by expressing ACE activity per milligram of lung protein, CDH-NS animals showed elevated specific ACE activity (P = .05) compared with OO-NS controls (6.31 +/- 1.1 v 4.4 +/- 0.4). CDH-Dex animals had a significantly lower specific ACE activity (P = .01) compared with CDH-NS and Non-CDH-NS rats (4.0 +/- 0.4 v 6.31 +/- 1.1 and 5.83 +/- 0.54). The specific ACE activity levels of CDH-Dex rats were equivalent to those seen in the lungs of OO-NS controls (P = .24).

CONCLUSION

Antenatal steroid therapy, by suppressing pulmonary ACE activity, may reduce the risk of pulmonary hypertension developing in human newborns with antenatally diagnosed CDH.

Effect of prenatal glucocorticoids on pulmonary vascular muscularisation in nitrofen-induced congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Pulmonary hypertension (PH) contributes significantly to the mortality of congenital diaphragmatic hernia (CDH). Pulmonary vascular changes in CDH include a reduced vascular bed with increased arterial medial wall thickness and peripheral extension of muscle into intraacinar vessels. Antenatal steroids improve biochemical immaturity, lung compliance, and morphology in experimental CDH animals. The aim of this study was to examine the effects of prenatal glucocorticoid therapy on pulmonary artery muscularisation in CDH rats.

METHODS

CDH was induced in fetal rats by the maternal administration of 100 mg of nitrofen by gavage on day 9.5 of gestation (term, day 22). Control animals received olive oil (OO). Dexamethasone (Dex, 0.25 mg/kg) or normal saline (NS) was given by intraperitoneal injection on days 18.5 and 19.5, and fetuses were delivered by caesarean section on day 21.5. Lung sections from five fetuses in each of four experimental groups were studied by a blinded investigator- OO-NS controls, CDH-NS, CDH-Dex, and non-CDH-NS. The external diameter (ED), medial wall thickness (MT), percent of medial wall thickness, and wall structure were evaluated from preacinar arteries accompanying conducting airways, and the intraacinar arterioles associated with the respiratory bronchi and saccules.

RESULTS

In the preacinar arteries, CDH-NS animals had a significantly increased MT percentage compared with OO-NS controls (21.2+/-8.8 v 17.8+/-10.3, P = .0001). CDH-Dex rats had a lower MT percentage than CDH-NS rats (15.5+/-6.7 v 21.2+/-8.8, P = .0001). In the intraacinar region, CDH-Dex fetuses had a reduced percentage of muscularised intraacinar blood vessels compared with CDH-NS and OO-NS controls (10% v 24% and 28%, respectively, P = .01). Dexamethasone-treated CDH pups also displayed a significantly lower MT percentage of the intraacinar arteries compared with CDH-NS and OO-NS animals (15.7+/-13 v 23.4+/-9 and 25.4+/-12, P = .003).

CONCLUSIONS

Medial hypertrophy is present in the preacinar but not the intraacinar blood vessels of CDH rats before birth. Dexamethasone inhibits medial hypertrophy and reduces the number of muscularised intraacinar vessels. Antenatal glucocorticoids may reduce the risk of PH developing in human newborns with antenatally diagnosed CDH.

No evidence of WT1 gene mutations in children with congenital diaphragmatic hernia

Children with congenital diaphragmatic hernia are born with a defect of the diaphragm that usually leads to a herniation of abdominal organs up into the thoracic cavity on the same side. The condition is often fatal, usually because of concomitant lung hypoplasia. The cause of this condition is unknown. The majority of cases are sporadic, but familial aggregation has been observed, indicating a genetic background. The tumor suppressor gene WT1 is involved in normal early urogenital development, and it is expressed in the mesothelium in the early human fetus. Recently, knockout mice homozygous for WT1 gene mutations were constructed. The embryos died between days 13 and 15 of gestation. Besides serious urogenital and thoracic malformations, the mice had defects in the diaphragm that caused herniation of lung tissue into the abdomen. These findings prompted the authors to screen for WT1 gene mutations in 27 children who had congenital diaphragmatic hernia. Using exon-per-exon polymerase chain reaction (PCR) amplifications and denaturing gradient gel electrophoresis, no WT1 mutations were detected. Southern blot analysis did not show any large rearrangements in the WT1 gene. These results exclude WT1 gene mutations as a major etiological factor for the isolated diaphragmatic defect. However, it is possible that other genes in the WT1 pathway are involved in this defect.

Improving survival for patients with high-risk congenital diaphragmatic hernia by using extracorporeal membrane oxygenation

The benefit of extracorporeal membrane oxygenation (ECMO) in cases of high-risk congenital diaphragmatic hernia (CDH) was studied by comparing pre-ECMO (1987-1990) and post-ECMO (1991-1994) 3-month survival statistics. Fifty-five CDH patients who presented in respiratory distress within 6 hours after birth were referred--18 in the pre-ECMO era and 37 in the ECMO era. During the entire study period (December 1987 through July 1994) the patients were treated by the same protocol of preoperative stabilization and delayed surgery; the only difference was the addition of ECMO beginning in January 1991. The patients were stratified based on the response to conventional treatment: 1, no response (irretrievable); 2, stable; 3, unstable. The 3-month survival rate for the unstable neonates (who could not be stabilized by conventional therapy) improved from 0% (0 of 9) in the pre-ECMO era to 61% (11 of 18) in the ECMO era (P = .004). This highly significant difference shows that ECMO is a very valuable addition to the management of high-risk CDH patients whose conditions remain unstable despite maximal conventional therapy.

Inhaled nitric oxide in congenital diaphragmatic hernia

Pulmonary hypertension is a major complication of congenital diaphragmatic hernia (CDH). Inhaled nitric oxide (NO) is a selective pulmonary vasodilator because it produces vasodilatation of the pulmonary vasculature without systemic hypotension. In experimental and clinical studies, inhaled NO ameliorates pulmonary hypertension and improves gas exchange. The goal of the present study was to determine the extent to which infants with CDH respond to inhaled NO. Four newborn infants with CDH complicated by severe respiratory insufficiency and right-to-left shunting received inhaled NO. In three patients, postductal oxygenation improved in response to small concentrations of NO (5 to 10 ppm); two received NO after operative repair, and the third both before and after repair. However, tachyphylaxis developed in all cases within 1 to 6 days. A fourth patient received inhaled NO in an attempt at weaning from ECMO. He did not respond, remaining hypoxic despite 80 ppm NO, and continued to require ECMO. In the three patients who responded to inhaled NO, plasma nitrites and nitrates (stable oxidative end products of NO) accumulated over time, but not in the patient who did not respond. The accumulation of nitrite and nitrate in plasma may reflect alveolar-capillary NO absorption, and may identify patients who will respond to continued inhaled NO. Methemoglobin remained below 1.9% in all four babies. Selected infants with CDH may respond to NO, but the benefit may be temporary.

Fetal lamb pulmonary hypoplasia: pulmonary vascular and myocardial abnormalities

Neonatal pulmonary hypoplasia resulting from a congenital diaphragmatic hernia (CDH) produces hemodynamic changes and morphologic abnormalities of the pulmonary vasculature. To characterize the myocardial and pulmonary vascular status of the fetus with pulmonary hypoplasia, we studied four chronically instrumented, near-term fetal lambs with pulmonary hypoplasia, induced by producing a diaphragmatic hernia. We found an elevation in the pulmonary arterial pressure (control, 43.8 +/- 5.9 mmHg; CDH, 58.8 +/- 9.1 mmHg; p < 0.05), an elevation in the systemic arterial pressure (control, 43.8 +/- 0.48 mmHg; CDH, 58.6 +/- 6.7 mmHg; p < 0.05), and an elevation in the pulmonary vascular resistance (control, 0.47 +/- 0.11; CDH, 3.87 +/- 1.9; p < 0.05). In addition, though the total pulmonary blood flow was reduced (control, 83.5 +/- 32.9 mL/min; CDH, 22.2 +/- 17.6 mL/min; p < 0.05), the blood flow reduction was proportional to the reduction in the lung mass (control, 79.8 +/- 28.1 [in flow per 100-g lung weight]; CDH, 85.4 +/- 71.7). The increase in the pulmonary vascular resistance in relation to the unit lung mass (control, 0.55 +/- 0.33; CDH, 0.99 +/- 0.5) was not as pronounced as its increase in relation to the total pulmonary blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive capabilities of preoperative and postoperative pulmonary function tests in delayed repair of congenital diaphragmatic hernia

To improve the survival of newborns with congenital diaphragmatic hernia (CHD), preoperative stabilization with conventional ventilatory therapy and extracorporeal membrane oxygenation (ECMO) have been used. Measurements that quantify pulmonary function may allow an accurate assessment of lethal pulmonary hypoplasia and predict outcome. Pulmonary function tests (PFTs) were obtained in 20 infants preoperatively and postoperatively; these included measurements of compliance, dynamic compliance, and tidal volume. Overall survival was 75%. Six surviving infants were initially managed with ventilator therapy alone, followed by repair (group 1). The remaining 14 patients, who were moribund at presentation or whose initial ventilator therapy failed, were placed on ECMO and received repair during bypass; nine survived (group 2), and five died (group 3). Compliance, dynamic compliance, and tidal volume obtained at initial presentation and immediately preoperatively were significantly higher for group 1 as compared with groups 2 and 3. Infants whose initial compliance was greater than 0.25 mL/cm H2O/kg and initial tidal volume was greater than 3.5 mL/kg did not require ECMO. Ultimate improvement in compliance was noted in 5 of 6 patients in group 1, 8 of 8 patients in group 2, and 5 of 5 in group 3. This improvement followed an initial decline in compliance in 9 of 14 survivors, from 15% to 76%. All six patients in group 1 had tidal volumes of more than 4 mL/kg, as did 7 of 9 patients in group 2. Only one patient among the ECMO nonsurvivors (group 3) had a postoperative tidal volume of this magnitude. These data suggest that initial PFTs may predict which infants will require ECMO.(ABSTRACT TRUNCATED AT 250 WORDS)

Advances in the treatment of persistent pulmonary hypertension of the newborn

Despite an association with meconium and blood aspiration, pneumonia, sepsis, pneumothorax, prematurity, and congenital diaphragmatic hernia, no cause for persistent pulmonary hypertension of the newborn can be found in many cases. This article discusses the advances in current therapies including the promising new therapy of inhaled nitric oxide.

A new method of treatment for pulmonary hypertension in congenital diaphragmatic hernia: experimental study in cats

This research proposes a new treatment for pulmonary hypertension secondary to perivascular emphysema, the so-called air-block syndrome. Vibrations applied on the thorax can fraction air bubbles around the vessels into smaller ones, facilitating their redistribution and reabsorption, thus reducing the extrinsic compression on pulmonary vasculature. In cats, pulmonary lesions were obtained by continuous insufflation of air at 40 cm H2O for 2 minutes in a lower lobe of the lung. Vibrations applied on the thorax were produced with the same apparatus as used by physiotherapists to eliminate pulmonary secretions. Thirty-three cats were divided into three groups: lesions without treatment, lesions treated by vibrations, and controls. A catheter was inserted in the pulmonary artery for pulmonary artery pressure (PAP) measurements. One carotid was cannulated for arterial pressure and blood gases monitoring. Morphometric analysis of the lung had also to be carried out in all cases. Results showed a very significant decrease on pulmonary hypertension in the treated group after only 20 minutes of treatment by vibrations (P < .004). Results also confirmed the very strong relationship between PAP variations and perivascular emphysema found on postmortem examination (r2 = .64, P < .01). Extrinsic compression decreased from 29% in the untreated group to 21% in the treated one (n = 10 pairs, P < .08). These data suggest that vibrations may be a new simple treatment for pulmonary hypertension, when perivascular emphysema is involved, and could be useful in congenital diaphragmatic hernia as well in other neonatal pathologies.

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.

Contemporary management of congenital diaphragmatic hernia

Despite advances in infant transport and intensive care, congenital diaphragmatic hernia (CDH) still poses a serious threat to life during the neonatal period. Only with the introduction of extracorporeal membrane oxygenation (ECMO) has mortality declined significantly. Understanding the pathophysiology of CDH and its devastating effect on the lungs' bronchial and vascular development assists the clinician in rational management during the perioperative period. Successful treatment demands prompt diagnosis, informed preoperative assessment and preparation, carefully timed surgical repair, and aggressive postoperative intensive care with a thorough understanding of the role of ECMO. Improvements in ventilatory support and pharmacologic management of pulmonary hypertension have allowed surgeons to delay repair until circulatory hemodynamics, electrolytes, and oxygenation can be optimized, even resorting to preoperative ECMO in selected cases if needed. Patients with severe bilateral pulmonary hypoplasia pose serious dilemmas in terms of selection for ECMO, as well as for surgical repair. Long-term follow-up of patients after CDH repair reveals persistent hypoperfusion of the involved lung but no debilitating pulmonary disease. Future therapies may include early fetal intervention or lung transplantation, although these areas remain controversial and experimental, and clinical experience is limited.

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.

Ventilation parameters and arterial blood gases as a prediction of hypoplasia in congenital diaphragmatic hernia

Attempts to predict the degree of pulmonary hypoplasia associated with congenital diaphragmatic hernia have been made by evaluating the ventilation parameters and the arterial blood gasses of these patients. A CO2 index as a predictor of outcome, which correlates the PaCO2 with the ventilation index, was recently proposed. However, in this study the postductal PaO2 was a better predictor of survival. And the so-called "honeymoon period" was a better indicator of the efficacy of extracorporeal membrane oxygenation (ECMO) than the CO2 index. Nineteen patients were evaluated; 11 were treated with ECMO, and eight were not considered suitable for ECMO.

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.

Clinical use of extracorporeal membrane oxygenation in the treatment of persistent pulmonary hypertension following surgical repair of congenital diaphragmatic hernia

The clinical use of extracorporeal membrane oxygenation (ECMO) in the treatment of persistent pulmonary hypertension following surgical repair of congenital diaphragmatic hernia is reported on 11 patients. The patients had a total of 13 treatments; two patients had two treatments. During the same period of clinical use, 122 patients were placed on ECMO for all causes. The indications, results, and complications of the use of ECMO for treatment following surgical repair of congenital diaphragmatic hernia are presented. The reversal of persistent pulmonary hypertension is demonstrated. All patients treated by ECMO for congenital diaphragmatic hernia have survived.

A correlation of pulmonary hypoplasia, mean airway pressure, and survival in congenital diaphragmatic hernia treated with extracorporeal membrane oxygenation

Thirty infants with congenital diaphragmatic hernia (CDH) who required therapy within the first day of life were treated in our institution over the past 3 years. Eighteen of these infants were not treated with extracorporeal membrane oxygenation (ECMO). Survival in this group was 83%. Twelve infants were treated with ECMO. Seven (58%) were weaned from ECMO and ventilator support with six (50%) long-term survivors. Minimum preoperative alveolar-arterial oxygen gradient (AaDO2), maximum postoperative mean airway pressure (MAP), and pulmonary hypoplasia were evaluated. Bohn et al have prospectively shown that the relationship of PaCO2 to mechanical ventilatory requirements accurately predicted survival in a group of 58 infants with CDH in whom ECMO was not a therapeutic option. This criteria would predict nonsurvival in all 12 of our patients treated with ECMO, including the seven survivors. Differences between our ECMO and non-ECMO groups were statistically significant for all three criteria. All P values less than .05. Morphometric analysis of the lungs of all ECMO nonsurvivors revealed hypoplastic ipsilateral lungs by lung weight to body weight ratios and radial alveolar counts when compared with experimental and historical controls (P less than .05). The contralateral lung was hypoplastic in 80% of the nonsurvivors. There is a strong correlation between the maximum postoperative MAP and the degree of contralateral pulmonary hypoplasia (r = .03, P = .02). We conclude that the maximum postoperative MAP is an accurate predictor of survival in the treatment of CDH and can be correlated with the degree of pulmonary hypoplasia.(ABSTRACT TRUNCATED AT 250 WORDS)

Unilateral agenesis of the diaphragm

During a period of 4 1/2 years, 37 infants with congenital diaphragmatic hernia were treated. The overall survival rate was 68%. Survival depended more on cardiopulmonary function than the size of the diaphragmatic defect. There was little evidence that infants with agenesis of the diaphragm formed a special group with a poor prognosis, and four of the ten patients with unilateral agenesis survived. A Dacron prosthesis is recommended as a substitute for the missing diaphragm.

Extracorporeal membrane oxygenation following repair of congenital diaphragmatic hernias

From 1981 through 1986, 8 newborns with congenital diaphragmatic hernia required herniorrhaphy in the first 8 hours of life. Extracorporeal membrane oxygenation (ECMO) was employed in 7 after they met local criteria predictive of 95% mortality. These criteria were an alveolar-postductal arterial oxygen gradient greater than 600 mm Hg for 12 hours or hemodynamic instability. Four of these 7 patients had unremitting hypoxemia after herniorrhaphy (no "honeymoon" period), 3 of whom survived. One additional patient died, producing a mortality of 29%. ECMO used for 68 to 241 hours (mean, 163 hours) provided reliable oxygenation in all. Deaths resulted from disseminated intravascular coagulation and bleeding, and bleeding and pulmonary failure after ligation of a patent ductus arteriosus. Complications occurred in 6 patients and included bleeding (3), hernia recurrence (3), and air embolism (1). Follow-up ranging from 1 year to 6 years after discharge of the 5 survivors shows normal growth and development in 4. The reported mortality without ECMO following congenital diaphragmatic herniorrhaphy in the first 8 hours of life ranges between 60 and 80%. While bleeding may present problems, survival of newborns with refractory hypoxemia after diaphragmatic repair has improved with ECMO.

Chest size and symmetry in congenital diaphragmatic hernia

Infants with congenital diaphragmatic hernia have significantly increased chest circumferences. This implies that intrathoracic volumes are increased as well. Forces produced by the herniated abdominal viscera seem to provide the chief impetus for this change. Other factors may also contribute, for thoracic enlargement is asymmetric and not always ipsilateral to the hernia. The contribution of an enlarged chest to respiratory insufficiency, persistence of the fetal circulation, and hyperinflation is not fully understood, but may have relevance in evaluating new approaches to therapy.

Prenatal diagnosis and management of some fetal intrathoracic abnormalities

Nine cases of fetal intrathoracic anomalies detected in utero and followed to birth are reviewed. There were 6 congenital diaphragmatic hernias (CDH), one congenital pleural effusion and two isolated cysts of the lung. All these conditions were potentially responsible for neonatal respiratory distress and received early intensive treatment after maternal transport and delivery had been arranged in a center with thoracic surgical facilities available. The risks of a delayed or missed diagnosis were thus avoided, especially for CDH. Despite intensive, traditional, respiratory support, started in the delivery room, mortality among prenatally detected cases of CDH was paradoxically high (83%), compared to mortality among 7 cases of CDH not detected in utero, referred in the same period to our Institution, and symptomatic within 6 h from birth (63%). With prenatal diagnosis the total number of CDH cases referred to a surgical center before birth increases. Many cases which would never have been treated in the past because of death before referral and treatment for severe pulmonary hypoplasia not compatible with life are thus observed and sometimes treated. Nevertheless, lung development continues to be a determining factor for survival even when intensive treatment at birth is available. Responsiveness to therapy is unpredictable before birth and proposed antenatal treatment is still far from being a realistic option. For the other three newborns, where a pleural effusion and pulmonary cysts were found, prenatal diagnosis helped to start appropriate treatment and to prevent neonatal hypoxia in two of them. In the third case, with an incommunicant, isolated pulmonary cyst, the outcome would have been favourable even without a prenatal diagnosis.

Improving survival in the treatment of congenital diaphragmatic hernia

Thirty-two infants were treated for congenital diaphragmatic hernia at our institution from 1979 to 1984. Eight were in no or minimal distress at birth and had operative intervention when they were more than 24 hours old; survival was 100%. The remaining 24 neonates required immediate intubation and ventilation followed by operation at less than 12 hours of age. Overall survival was 54%; survival was 31% (4 of 13 patients, Group 1) in the first three years of the series and 82% (9 of 11 patients, Group 2) in the last three years (p less than 0.001). Apgar score, gestational age, birth weight, and incidence of associated congenital heart disease were equal for the two groups (all, p greater than 0.05). The two groups also were examined with reference to alveolar-arterial oxygen differences P(A-a)O2 and mean airway pressure (MAP). The best preoperative P(A-a)O2 was greater than 600 mm Hg for 7 neonates in Group 1 and 6 in Group 2, and survival was 0% and 71%, respectively (p less than 0.001). Infants with a postoperative MAP of 13 cm H2O or greater had a higher mortality (100% in Group 1 and 50% in Group 2, p greater than 0.05). Our treatment protocol was studied to determine those methods related to improved survival. Sodium bicarbonate infusion was used earlier in Group 2 as a prophylaxis against persistent fetal circulation (PFC) (p greater than 0.05). The incidence of severe PFC dropped from 85 to 54% (p greater than 0.05). Higher ventilator rates rather than pressures were used to achieve equally effective ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)

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

Congenital diaphragmatic hernia continues to be a critical problem in neonatal surgery. Despite the apparent simplicity of the anatomic defect, the physiology is complex, and survival remains uncertain. Surgical success has been achieved, but we recognize that the barrier to survival is pulmonary parenchymal and vascular hypoplasia as well as the complex syndrome of persistent fetal circulation. In many ways the problem of diaphragmatic hernia is as much of an enigma to today's physician-scientist as it was to Bochdalek in the nineteenth century. The treatment of respiratory distress after repair of congenital diaphragmatic hernia has brought out the most creative and innovative efforts of pediatric surgeons in both the laboratory and the intensive care unit.

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.

"Balanced" thoracic drainage is the method of choice to control intrathoracic pressure following repair of diaphragmatic hernia

Respiratory failure from pulmonary hypoplasia continues to be the major cause of death in newborn infants with diaphragmatic hernia. Recent investigations have suggested that postnatally induced pulmonary injury can result from excessive positive or negative intrathoracic pressure and contribute to the respiratory deterioration. Therefore, the method of thoracic drainage on the side of the diaphragmatic hernia is critical in controlling and maintaining normal intrathoracic pressure in both intrathoracic spaces. No chest tube or an ipsilateral chest tube connected to water seal, can result in either excessive negative or positive intrathoracic pressure and, therefore, both methods should be avoided. Recently, we employed a "balanced" intrathoracic drainage system which maintains the ipsilateral intrathoracic pressure within the normal physiologic range of +2 to -8 cm H2O regardless of the degree of pulmonary hypoplasia, presence of an ipsilateral pulmonary air leak, straining by the infant, or mechanical ventilation. This system is simple, requires no suction apparatus, and is easily assembled with equipment readily available within the hospital. This technique has been utilized in 18 newborn infants with diaphragmatic hernia and pulmonary hypoplasia. There have been no complications which specifically could be related to the balanced drainage system.

Strangulated congenital diaphragmatic hernia in infants

Two previously healthy children, 7 and 12 months old, respectively, presented with respiratory distress and severe sepsis. Chest x-rays were suggestive of inflammatory disease of the left lung. At operation, necrotic bowel was found to be herniated through a left congenital posterolateral diaphragmatic hernia. These patients illustrate the difficulty in establishing the diagnosis of strangulated congenital diaphragmatic hernia and the grave consequences when operation is delayed.

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.

Alveolar-arterial oxygen gradients versus the Neonatal Pulmonary Insufficiency Index for prediction of mortality in ECMO candidates

Current selection criteria necessary for intelligent application of extracorporeal membrane oxygenation (ECMO) in hypoxic neonates remains controversial. Both the Neonatal Pulmonary Insufficiency Index (NPII) and serial alveolar-arterial oxygenation gradient measurements (A-a)Do2 have been recommended. Accordingly, an analysis of 50 consecutive severely hypoxic neonates was undertaken to assess the predictive value of (A-a)Do2 determinations and NPII in discriminating survivors from non-survivors. These infants with meconium aspiration syndrome (MAS), congenital diaphragmatic hernia (CDH), or persistent pulmonary hypertension of the newborn (PPHN) required maximum mechanical ventilation for hypoxia. Pharmacologic manipulation of pulmonary vascular resistance was attempted in 83%. If postductal (A-a)Do2 remained greater than or equal to 620 torr despite 12 hours of maximum medical therapy, mortality was 100%; however, 35% of nonsurvivors were unfortunately excluded. (A-a)Do2 greater than or equal to 600 torr for 12 hours demonstrated 93.8% mortality, and only 12% of all mortalities were thus excluded. Among nonsurvivors successfully hyperventilated, the NPII could not predict mortality. Ideal selection criteria must exclude those who would otherwise survive without ECMO, yet allow early accurate identification of the neonate certain to die. It would appear that serial (A-a)Do2 determinations best permit this identification and thus orderly application of ECMO.

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.

The advantages of reconstruction of the dome of the diaphragm in congenital posterolateral diaphragmatic defects

Repair of a congenital posterolateral diaphragmatic defect (CPLDD) by direct suture results in a flat drum-head diaphragm, which has very little function. Other harmful effects of such a repair include enlargement of the thoracic cavity, resulting in more overexpansion of the hypoplastic lungs which may contribute to pulmonary vascular obstruction, and decrease in volume of the abdominal cavity, making closure of the laparotomy difficult. Reconstruction of a diaphragmatic dome would result in a more functional diaphragm and would prevent the above complications. This was substantiated in a series of 10 babies, all severely symptomatic from birth and treated according to the proposed technique. Eight babies survived, the two deaths occurring 36 hours and 3 months after surgery, in babies with severe cardiac anomalies. It is concluded that reconstruction of the dome of the diaphragm in patients with a CPLDD is well tolerated and may result in an increased survival.

The "critical" neonate with diaphragmatic hernia: a 21-year perspective

We have seen a modest improvement in the survival of a homogeneous group of critically ill newborns with congenital diaphragmatic hernia since 1979. Twenty-seven "critical" infants have been treated who developed respiratory distress shortly after birth, required urgent resuscitation, and could not be stabilized before operation. Two died with other anomalies that appeared incompatible with prolonged survival. Ten of the 27 lived. This survival contrasts with that of only two of 17 similarly affected babies treated from 1962 to 1978. In addition, there has been no operative mortality outside of this "critical" group since 1979; whereas six noncritical babies died between 1967 to 1978. Our current therapeutic plan includes the early establishment of a respiratory alkalosis and vasodilator therapy before or during transport. Postoperatively we have attempted to maintain the baby's arterial pH greater than 7.5, Pco2 less than 25 to 30 and the PO2 approximately 150 torr. The most effective ventilatory parameters have been a rate of 130, PEEP of 5 and an inspiratory:expiratory ratio of 1:1. Peak airway pressures are kept as low as possible. Pharmacologic and ventilator therapy are weaned slowly, and intensive support has been required for at least 48 hours in each baby. Retained secretions and atelectasis of the hypoplastic lung persisted for two to several weeks postoperatively. Two babies that are one year or older still appear to have severely hypoplastic lungs on chest x-ray. M-mode echocardiography has been used to measure ventricular ejection periods. The right ventricular systolic time interval correlates with the degree of pulmonary hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Creation and repair of diaphragmatic hernia in the fetal lamb: lung development and morphology

Left-sided diaphragmatic hernias were created in 26 lambs at about 78 days' gestation and repaired at 106 to 124 days' gestation. Nine of these lambs were delivered at term and lived much longer than the nonrepaired lambs delivered at term. The normal development of the fetal lamb lung is compared and contrasted with the development of the lung after creation of a diaphragmatic hernia and also with the changes in morphology resulting from in-utero repair. Creation of a diaphragmatic hernia resulted in marked delay in the development of alveoli and at term the lung had small, thick-walled terminal air-spaces with few capillaries and no true alveoli when compared with the thin-walled alveoli in normal lungs. Another striking feature was an apparent increase in the frequency of type II alveolar cells in diaphragmatic hernia lungs. In-utero repair of the diaphragmatic hernia resulted in a more normal appearance with true alveoli developing by term, although capillaries appeared to be less numerous and type II cells more numerous than in normal lungs. Surprisingly, there appears to be little difference between the left and right lungs in lambs with diaphragmatic hernia.

Lethal nonpulmonary anomalies associated with congenital diaphragmatic hernia: implications for early intrauterine surgery

Recently, interest has been expressed in the correction of diaphragmatic hernia in utero as a solution to the problem of high mortality from this condition. Before such a procedure can be adopted in the human, studies aimed at establishing the contribution such advanced techniques would make in reducing mortality are required. Between 1973 and 1982, there were 36 cases of congenital diaphragmatic hernia among 75,512 births--an incidence of 1 in 2097 births. there were 11 (31%) stillbirths and 25 (69%) livebirths. the liveborn patients were divided into two groups: group A included 15 patients who died prior to transfer to the referral center; group B included ten neonates who arrived at the referral center and were operated upon. Twenty (56%) cases of diaphragmatic hernia (11 stillbirths and 9 liveborns who did not live long enough to be transferred to the referral center) were found to have lethal nonpulmonary associated anomalies at autopsy. In view of the high association of lethal anomalies it appears that fetal surgery would have a limited role in reducing mortality in congenital diaphragmatic hernia.

Iatrogenic pneumothorax and mortality in congenital diaphragmatic hernia

In a review of 22 infants who underwent surgical repair of congenital diaphragmatic hernias, it was noted that one of the most common factors correlating with death was perioperative tension pneumothorax. Each of the seven infants who died developed an iatrogenic pneumothorax with air leak due to face-mask or endotracheal ventilation with pressures in excess of 34 cm H2O, or to thoracentesis. Only two infants with tension pneumothorax survived. Infants who developed tension pneumothorax experienced severe respiratory distress at an earlier age and required more vigorous resuscitative measures than those infants without an air leak.

Reversion to fetal circulation in congenital diaphragmatic hernia: a preventable postoperative complication

A review of 26 patients with congenital diaphragmatic hernia, diagnosed in the first 24 hours of life, supports the hypothesis that the postoperative fetal circulation syndrome is an iatrogenic complication, due to the rapid expansion of both lungs, when they are severely hypoplastic. This complication is preventable, when no aspiration of air from the chest cavity is done, and when no tube attached to an underwater seal is inserted. When assisted ventilation is necessary, small volumes at a rapid rate allows satisfactory gaseous exchanges, without pulmonary overinflation.

Management of neonatal posterolateral diaphragmatic hernia

From March 1978 to April 1982 13 neonates with a left posterolateral diaphragmatic hernia were seen in respiratory distress within 12 hours of birth. Each had severe acidosis and hypoxia. They were immediately intubated and ventilated. Arterial and central venous lines were inserted, the acidosis was partially corrected, and a dopamine infusion of 4-8 micrograms/kg/min was begun immediately. Continuous monitoring of arterial and venous pressures, core and skin temperatures, blood gases, and pH was instituted. Diaphragmatic defects were repaired by direct suture in nine neonates and by Gore-Tex patches in four. The left lung in all patients was hypoplastic. Ventilation and inotropic support were continued for four to five days after operation and close control of acid-base balance was maintained. All but one survive and are doing well. We consider the key to survival to be management of the dangerous combination of acidosis (by enhancing peripheral and renal perfusion with dopamine) and hypoxia (by prolonged assisted ventilation).

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.