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

Predictors of extubation success: a population-based study of neonates below a gestational age of 26 weeks

OBJECTIVE

The aim of the study was to investigate first extubation attempts among extremely premature (EP) infants and to explore factors that may increase the quality of clinical judgement of extubation readiness.

DESIGN AND METHOD

A population-based study was conducted to explore first extubation attempts for EP infants born before a gestational age (GA) of 26 weeks in Norway between 1 January 2013 and 31 December 2018. Eligible infants were identified via the Norwegian Neonatal Network database. The primary outcome was successful extubation, defined as no reintubation within 72 hours after extubation.

RESULTS

Among 482 eligible infants, 316 first extubation attempts were identified. Overall, 173 (55%) infants were successfully extubated, whereas the first attempt failed in 143 (45%) infants. A total of 261 (83%) infants were extubated from conventional ventilation (CV), and 55 (17%) infants were extubated from high-frequency oscillatory ventilation (HFOV). In extubation from CV, pre-extubation fraction of inspired oxygen (FiO₂) ≤0.35, higher Apgar score, higher GA, female sex and higher postnatal age were important predictors of successful extubation. In extubation from HFOV, a pre-extubation FiO₂ level ≤0.35 was a relevant predictor of successful extubation.

CONCLUSIONS

The correct timing of extubation in EP infants is important. In this national cohort, 55% of the first extubation attempts were successful. Our results suggest that additional emphasis on oxygen requirement, sex and general condition at birth may further increase extubation success when clinicians are about to extubate EP infants for the first time.

Early Abnormalities in Gas Exchange in Infants with Congenital Diaphragmatic Hernia

OBJECTIVE

To determine how blood gas exchange is altered during the transition in the first hour of life in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

This was a prospective observational cohort study evaluating arterial blood gas (ABG) samples and ventilator support in 34 infants with CDH in the first hour of life. Infants were stratified into mild, moderate, and severe CDH. The first ABG was compared with the umbilical cord ABGs and response to intervention evaluated on subsequent ABGs among infants with different CDH severities.

RESULTS

Infants were intubated at a median of 120 seconds (range 50-240 seconds) and ABGs obtained at a median of 6 minutes (IQR 4, 8 minutes), 16 minutes (IQR 13.5, 22.5 minutes), and 60 minutes (IQR 56, 64 minutes). Compared with the cord ABG, first ABG mean partial pressure of carbon dioxide (PaCO₂) increased from 49.8 mm Hg to 82.1 mm Hg, mean base deficit decreased from -2.2 to -7.3, and mean pH from 7.298 to 7.060. With ventilator adjustments, second mean PaCO₂ decreased to 76.7 mm Hg and third mean PaCO₂ 48.5 mm Hg. When stratified, with all CDH severities PaCO₂ increased abruptly, remained elevated in moderate and severe CDH, and improved in all severities by 60 minutes after delivery.

CONCLUSIONS

Gas exchange is markedly altered in the first hour of life in infants with CDH with abrupt onset of acidemia and a mixed respiratory and metabolic acidosis. Early implementation of adequate cardiopulmonary support may contribute to more timely stabilization of gas exchange.

Congenital diaphragmatic hernia: a narrative review of controversies in neonatal management

The consequences of most hernias can be immediately corrected by surgical repair. However, this isn't always the case for children born with a congenital diaphragmatic hernia. The derangements in physiology encountered immediately after birth result from pulmonary hypoplasia and hypertension caused by herniation of abdominal contents into the chest early in lung development. This degree of physiologic compromise can vary from mild to severe. Postnatal management of these children remains controversial. Although heavily studied, multi-institutional randomized controlled trials are lacking to help determine what constitutes best practice. Additionally, the results of the many studies currently within the literature that have investigated differing aspect of care (i.e., inhaled nitric oxide, ventilator type, timing of repair, role of extracorporeal membrane oxygenation, etc.) are difficult to interpret due to the small numbers investigated, the varying degree of physiologic compromise, and the contrasting care that exists between institutions. The aim of this paper is to review areas of controversy in the care of these complex kids, mainly: the use of fraction of inspired oxygen, surfactant therapy, gentle ventilation, mode of ventilation, medical management of pulmonary hypertension (inhaled nitric oxide, sildenafil, milrinone, bosentan, prostaglandins), the utilization of extracorporeal membrane oxygenation, and the timing of surgical repair.

Computed tomography based measurements to evaluate lung density and lung growth after congenital diaphragmatic hernia

Emphysema-like-change of lung is one aspect of lung morbidity in children after congenital diaphragmatic hernia (CDH). This study aims to evaluate if the extent of reduced lung density can be quantified through pediatric chest CT examinations, if side differences are present and if emphysema-like tissue is more prominent after CDH than in controls. Thirty-seven chest CT scans of CDH patients (mean age 4.5 ± 4.0 years) were analyzed semi-automatically and compared to an age-matched control group. Emphysema-like-change was defined as areas of lung density lower than - 950 HU in percentage (low attenuating volume, LAV). A p-value lower than 0.05 was regarded as statistically significant. Hypoattenuating lung tissue was more frequently present in the ipsilateral lung than the contralateral side (LAV 12.6% vs. 5.7%; p < 0.0001). While neither ipsilateral nor contralateral lung volume differed between CDH and control (p > 0.05), LAV in ipsilateral (p = 0.0002), but not in contralateral lung (p = 0.54), was higher in CDH than control. It is feasible to quantify emphysema-like-change in pediatric patients after CDH. In the ipsilateral lung, low-density areas are much more frequently present both in comparison to contralateral and to controls. Especially the ratio of LAV ipsilateral/contralateral seems promising as a quantitative parameter in the follow-up after CDH.

Predicting lethal pulmonary hypoplasia in congenital diaphragmatic hernia (CDH): Institutional experience combined with CDH registry outcomes

BACKGROUND

The Severe Pulmonary Hypoplasia and Evaluation for Resuscitative Efforts (SPHERE) protocol was developed to attempt to identify CDH patients with likely lethal pulmonary hypoplasia. We present our experience with this protocol and utilize the CDH Registry to critically assess the protocol.

METHODS

SPHERE patients identified based on prenatal imaging (10/2009-1/2018) were offered ECMO if meeting postnatal physiologic criteria, while others received comfort measures. Within the CDH Registry, patients with suspected severe CDH were identified and separated into "passed" (lowest pCO2 ≤100) versus "failed" (lowest pCO2 >100) groups.

RESULTS

Of 23 SPHERE patients, 57% (13/23) passed criteria for ECMO and survival was 46% (6/13) in that cohort. Of 4912 patients in the CDH Registry, 265 met criteria. There was no difference in survival rates between those that "passed" (122/227; 54%) versus "failed" (18/38; 47%). However, the latter had longer ECMO runs and more required ventilator/ECMO support at 30 days. Amongst survivors, the "failed" group had longer hospital stays and more frequently required tube feeds at discharge.

CONCLUSIONS

The SPHERE protocol did not predict mortality in the CDH Registry. However, our data suggest resource utilization is significant when unable to reach pCO2 ≤100 despite resuscitation. Morbidity remains high in this group.

LEVEL OF EVIDENCE

Level III ANNOTATION OF CHANGES: Institutional Review Board Approval at University of Michigan (HUM00031524 and HUM00044010) TYPE OF STUDY: Retrospective Review.

Perinatal Undernutrition, Metabolic Hormones, and Lung Development

Maternal and perinatal undernutrition affects the lung development of litters and it may produce long-lasting alterations in respiratory health. This can be demonstrated using animal models and epidemiological studies. During pregnancy, maternal diet controls lung development by direct and indirect mechanisms. For sure, food intake and caloric restriction directly influence the whole body maturation and the lung. In addition, the maternal food intake during pregnancy controls mother, placenta, and fetal endocrine systems that regulate nutrient uptake and distribution to the fetus and pulmonary tissue development. There are several hormones involved in metabolic regulations, which may play an essential role in lung development during pregnancy. This review focuses on the effect of metabolic hormones in lung development and in how undernutrition alters the hormonal environment during pregnancy to disrupt normal lung maturation. We explore the role of GLP-1, ghrelin, and leptin, and also retinoids and cholecalciferol as hormones synthetized from diet precursors. Finally, we also address how metabolic hormones altered during pregnancy may affect lung pathophysiology in the adulthood.

Comparison of early postnatal prediction models for survival in congenital diaphragmatic hernia

OBJECTIVE

To compare the PF-PCO₂ equation-partial pressure of arterial oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) minus partial pressure of carbon dioxide (PCO₂)-to three other tools for postnatal prediction of survival in infants with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

A retrospective analysis of 203 infants with CDH from 1 January 2003 to 30 June 2018. Area under the curve (AUC) analysis was performed for survival and secondary outcomes of survival without extracorporeal membrane oxygenation support (ECMO) and death despite ECMO. Predictive scores were calculated to determine cutoff for PF-PCO₂ score.

RESULTS

The PF-PCO₂ tool had the highest AUC (0.84 for survival, 0.92 for survival without ECMO, and 0.83 for death despite ECMO). PF-PCO₂ best predicted survival when >-60 and survival without ECMO when >+80. There was no optimal cutoff score for death despite ECMO.

CONCLUSION

The PF-PCO₂ tool best predicted postnatal survival in infants with CDH.

Lower Distending Pressure Improves Respiratory Mechanics in Congenital Diaphragmatic Hernia Complicated by Persistent Pulmonary Hypertension

OBJECTIVE

To investigate the effects of distending pressures on respiratory mechanics and pulmonary circulation in newborn infants with congenital diaphragmatic hernia (CDH) and persistent pulmonary hypertension (PPHN).

STUDY DESIGN

In total, 17 consecutive infants of ≥37 weeks of gestational age with CDH and PPHN were included in this prospective, randomized, crossover pilot study. Infants were assigned randomly to receive 2 or 5 cmH₂O of positive end-expiratory pressure (PEEP) for 1 hour in a crossover design. The difference between peak inspiratory pressure and PEEP was kept constant. Respiratory mechanics, lung function, and hemodynamic variables assessed by Doppler echocardiography were measured after each study period.

RESULTS

At 2 cmH₂O of PEEP, tidal volume and minute ventilation were greater (P < .05), and respiratory system compliance was 30% greater (P < .05) than at 5 cmH₂O. PaCO₂ and ventilation index were lower at 2 cmH₂O than at 5 cmH₂O (P < .05). Although preductal peripheral oxygen saturation was similar at both PEEP levels, postductal peripheral oxygen saturation was lower (median [range]: 81% [65-95] vs 91% [71-100]) and fraction of inspired oxygen was greater (35% [21-70] vs 25% [21-60]) at 5 cmH₂O. End-diastolic left ventricle diameter, left atrium/aortic root ratio, and pulmonary blood flow velocities in the left pulmonary artery were lower at 5 cmH₂O.

CONCLUSIONS

After surgical repair, lower distending pressures result in better respiratory mechanics in infants with mild-to-moderate CDH. We speculate that hypoplastic lungs in CDH are prone to overdistension, with poor tolerance to elevation of distending pressure.

Congenital diaphragmatic hernia: outcomes of neonates treated at Mayo Clinic with and without extracorporeal membrane oxygenation

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a rare anomaly with high mortality and long-term comorbid conditions.

AIMS

Our aim was to describe the presenting characteristics, treatment, and outcomes of consecutive patients with CDH treated at our institution.

METHODS

We performed a retrospective cohort study and identified consecutive neonates treated for CDH from 2001 to 2015 at our institution. For all patients identified, we reviewed hospital and postdischarge data for neonatal, disease, and treatment characteristics. We determined hospital survival overall and also according to the presence of prenatal diagnosis, liver herniation into the chest (liver up), and the use of extracorporeal membrane oxygenation (ECMO) in addition to surgery. We evaluated postdischarge chronic conditions in patients with at least one year of follow-up.

RESULTS

Thirty-eight neonates were admitted for treatment during the study period. In three who were in extremis, life support was withdrawn. The other 35 underwent surgical repair, of whom eight received ECMO. The overall survival was 79% (30/38). Survival for those who had surgical correction of CDH but did not need ECMO was 89% (24/27); it was 75% (6/8) for those who received ECMO and had surgery. Hospital survival was lower for liver-up vs liver-down CDH (61% [11/18] vs 95% [19/20]; odds ratio, 0.08; 95% CI, 0.01-0.77; P = 0.01). Among survivors, the median duration of hospitalization was 31 (interquartile range, 20-73) days. Major chronic pulmonary and gastrointestinal disorders, failure to thrive, and neurodevelopmental delays were the most noted comorbid conditions after discharge, and all were more prevalent in those who required ECMO.

CONCLUSION

The overall survival of neonates with CDH was 79%. Intrathoracic liver herniation was associated with more frequent use of ECMO and greater mortality. A substantial number of survivors, especially those who required ECMO, experienced chronic conditions after discharge.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

Role of admission gas exchange measurement in predicting congenital diaphragmatic hernia survival in the era of gentle ventilation

BACKGROUND/PURPOSE

Neonates with significant congenital diaphragmatic hernia (CDH) require cardiopulmonary support. Management has been characterized by progressive abandonment of hyperventilation. Ability to prognosticate outcomes using measures of ventilation and oxygenation with gentle ventilation remains unclear. We sought to determine whether assessment of gas exchange at the time of NICU admission is predictive of survival in this current era.

METHODS

Neonates with CDH admitted to a Children's Hospital from 1995 to 2006 were evaluated for demographics, blood gas (ABG) measurements and ventilator settings for the first 48hours, and discharge outcome.

RESULTS

One-hundred-and-nineteen CDH patients were admitted, 88 (74%) survived. Mean admission ABG pCO2 was higher in infants who died compared to survivors (86±48 versus 49±20, p≤0.001); positive predictive value (PPV) for mortality of pCO2≥80mmHg was 0.71. Mean first hour preductal oxygen saturation (preductalO2Sat) was lower in infants who died compared to survivors (81±17 versus 97±5, p<0.001); PPV for mortality of preductalO2Sat<85% was 0.82. Eleven patients met both pCO2 and preductalO2Sat criteria, and 10 (91%) died, PPV of 0.92. Within hours of admission, pCO2 and preductalO2Sat differences between survivors and nonsurvivors lost significance.

CONCLUSION

Admission pCO2 and preductalO2Sat may be useful in predicting survival in neonatal CDH. The differential in gas exchange between survivors and nonsurvivors loses significance with contemporary neonatal care.

A novel in vitro model to study alveologenesis

Many pediatric pulmonary diseases are associated with significant morbidity and mortality due to impairment of alveolar development. The lack of an appropriate in vitro model system limits the identification of therapies aimed at improving alveolarization. Herein, we characterize an ex vivo lung culture model that facilitates investigation of signaling pathways that influence alveolar septation. Postnatal Day 4 (P4) mouse pup lungs were inflated with 0.4% agarose, sliced, and cultured within a collagen matrix in medium that was optimized to support cell proliferation and promote septation. Lung slices were grown with and without 1D11, an active transforming growth factor-β-neutralizing antibody. After 4 days, the lung sections (designated P4 + 4) and noncultured lung sections were examined using quantitative morphometry to assess alveolar septation and immunohistochemistry to evaluate cell proliferation and differentiation. We observed that the P4 + 4 lung sections exhibited ex vivo alveolarization, as evidenced by an increase in septal density, thinning of septal walls, and a decrease in mean linear intercept comparable to P8, age-matched, uncultured lungs. Moreover, immunostaining showed ongoing cell proliferation and differentiation in cultured lungs that were similar to P8 controls. Cultured lungs exposed to 1D11 had a distinct phenotype of decreased septal density when compared with untreated P4 + 4 lungs, indicating the utility of investigating signaling in these lung slices. These results indicate that this novel lung culture system is optimized to permit the investigation of pathways involved in septation, and potentially the identification of therapeutic targets that enhance alveolarization.

A simplified formula using early blood gas analysis can predict survival outcomes and the requirements for extracorporeal membrane oxygenation in congenital diaphragmatic hernia

The aims of this study were to investigate whether early arterial blood gas analysis (ABGA) could define the severity of disease in infants with congenital diaphragmatic hernia (CDH). We conducted a retrospective study over a 21-yr period of infants diagnosed with CDH. Outcomes were defined as death before discharge, and extracorporeal membrane oxygenation requirements (ECMO) or death. A total 114 infants were included in this study. We investigated whether simplified prediction formula [PO2-PCO2] values at 0, 4, 8, and 12 hr after birth were associated with mortality, and ECMO or death. The area under curve (AUC) of receiver operating characteristic curve was used to determine the optimum ABGA values for predicting outcomes. The value of [PO2-PCO2] at birth was the best predictor of mortality (AUC 0.803, P < 0.001) and at 4 hr after birth was the most reliable predictor of ECMO or death (AUC 0.777, P < 0.001). The value of [PO2-PCO2] from ABGA early period after birth can reliably predict outcomes in infants with CDH.

Stability prior to surgery in Congenital Diaphragmatic Hernia: is it necessary?

BACKGROUND

Delaying surgery for infants with CDH until they achieve clinical stability is common practice. Stability, however, is inconsistently defined, and many infants fail to reach pre-established criteria. We sought to determine if infants undergoing surgery without meeting pre-established criteria could achieve meaningful survival.

METHODS

All infants in the CAPSNet database were analyzed (2005-2010). Patients undergoing operative repair were divided into two groups based on whether they met strict (FiO2<0.40, conventional ventilation, preductal saturation >92%, no inotropes or vasodilators), or lenient (FiO2 <0.60, conventional ventilation, preductal saturation >88%, no vasodilators) criteria. Univariate analyses were performed comparing characteristics of those who survived after surgery (N=273) with those who did not (N=21).

RESULTS

294 patients (85%) survived to surgery. Predictors of post-operative survival included prenatal liver position (p=0.003), preoperative oxygen requirements (p=0.008), preoperative inotropes (p<0.0001), and non-conventional ventilation (p=0.004). Infants meeting strict criteria had increased survival (99%; p<0.0001). Infants meeting lenient criteria constituted 70% of survivors. Nearly one-third of survivors met neither strict nor lenient criteria.

CONCLUSIONS

Infants with CDH can achieve good survival even when criteria for pre-operative stability are not met. We suggest that all infants should be repaired even if lenient criteria for ventilatory, inotrope, or vasodilator requirements are not achieved.

Is the time necessary to obtain preoperative stabilization a predictive index of outcome in neonatal congenital diaphragmatic hernia?

Background. The study aims to verify if the time of preoperative stabilization (≤24 or >24 hours) could be predictive for the severity of clinical condition among patients affected by congenital diaphragmatic hernia. Methods. 55 of the 73 patients enrolled in the study achieved presurgical stabilization and underwent surgical correction. Respiratory and hemodynamic indexes, postnatal scores, the need for advanced respiratory support, the length of HFOV, tracheal intubation, PICU, and hospital stay were compared between patients reaching stabilization in ≤24 or >24 hours. Results. Both groups had a 100% survival rate. Neonates stabilized in ≤24 hours are more regular in the postoperative period and had an easier intensive care path; those taking >24 hours showed more complications and their care path was longer and more complex. Conclusions. The length of preoperative stabilization does not affect mortality, but is a valid parameter to identify difficulties in survivors' clinical pathway.

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.

Antenatal sildenafil treatment attenuates pulmonary hypertension in experimental congenital diaphragmatic hernia

BACKGROUND

Lung hypoplasia and persistent pulmonary hypertension of the newborn limit survival in congenital diaphragmatic hernia (CDH). Unlike other diseases resulting in persistent pulmonary hypertension of the newborn, infants with CDH are refractory to inhaled nitric oxide (NO). Nitric oxide mediates pulmonary vasodilatation at birth in part via cyclic GMP production. Phosphodiesterase type 5 (PDE5) limits the effects of NO by inactivation of cyclic GMP. Because of the limited success in postnatal management of CDH, we hypothesized that antenatal PDE5 inhibition would attenuate pulmonary artery remodeling in experimental nitrofen-induced CDH.

METHODS AND RESULTS

Nitrofen administered at embryonic day 9.5 to pregnant rats resulted in a 60% incidence of CDH in the offspring and recapitulated features seen in human CDH, including structural abnormalities (lung hypoplasia, decreased pulmonary vascular density, pulmonary artery remodeling, right ventricular hypertrophy), and functional abnormalities (decreased pulmonary artery relaxation in response to the NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide). Antenatal sildenafil administered to the pregnant rat from embryonic day 11.5 to embryonic day 20.5 crossed the placenta, increased fetal lung cyclic GMP and decreased active PDE5 expression. Antenatal sildenafil improved lung structure, increased pulmonary vessel density, reduced right ventricular hypertrophy, and improved postnatal NO donor 2-(N,N-diethylamino)-diazenolate-2-oxide-induced pulmonary artery relaxation. This was associated with increased lung endothelial NO synthase and vascular endothelial growth factor protein expression. Antenatal sildenafil had no adverse effect on retinal structure/function and brain development.

CONCLUSIONS

Antenatal sildenafil improves pathological features of persistent pulmonary hypertension of the newborn in experimental CDH and does not alter the development of other PDE5-expressing organs. Given the high mortality/morbidity of CDH, the potential benefit of prenatal PDE5 inhibition in improving the outcome for infants with CDH warrants further studies.

Regulation of the Pulmonary Circulation in the Fetus and Newborn

During the development of the pulmonary vasculature in the fetus, many structural and functional changes occur to prepare the lung for the transition to air breathing. The development of the pulmonary circulation is genetically controlled by an array of mitogenic factors in a temporo-spatial order. With advancing gestation, pulmonary vessels acquire increased vasoreactivity. The fetal pulmonary vasculature is exposed to a low oxygen tension environment that promotes high intrinsic myogenic tone and high vasocontractility. At birth, a dramatic reduction in pulmonary arterial pressure and resistance occurs with an increase in oxygen tension and blood flow. The striking hemodynamic differences in the pulmonary circulation of the fetus and newborn are regulated by various factors and vasoactive agents. Among them, nitric oxide, endothelin-1, and prostaglandin I2 are mainly derived from endothelial cells and exert their effects via cGMP, cAMP, and Rho kinase signaling pathways. Alterations in these signaling pathways may lead to vascular remodeling, high vasocontractility, and persistent pulmonary hypertension of the newborn.

Predictors of survival in congenital diaphragmatic hernia patients requiring extracorporeal membrane oxygenation: CNMC 15-year experience

OBJECTIVE

To review outcomes of patients with congenital diaphragmatic hernia (CDH) requiring extracorporeal membrane oxygenation (ECMO) at a level IIIC neonatal intensive care unit and to determine if pre-ECMO respiratory status can help predict mortality.

STUDY DESIGN

A single-center retrospective chart review was conducted on all infants with CDH treated with ECMO in the past 15 years. Demographic and clinical information, including pre-ECMO ventilatory and blood gas data, was collected. Differences between survivors and non-survivors were evaluated using independent samples t-/Mann-Whitney U-and Fisher's exact/chi (2)-tests for continuous and categorical data, respectively. Cox regression analysis was performed to evaluate predictors of survival while controlling for covariates. Significant predictors were further explored with receiver operating characteristic (ROC) curve and Kaplan-Meier survival analysis.

RESULT

Overall survival of the population of 62 patients treated with ECMO was 50%. Survivor and non-survivors were similar in birth weight, gestational age, gender, race and Apgar scores. Approximately 80% of patients in both groups had a left-sided defect. Less than half of patients were prenatally diagnosed in either group. Patients in the non-survivor group had associated anomalies (42 vs 23% for survivors) but this was not statistically significant (P=0.303). Non-survivors were more likely to be put on ECMO earlier, stay on ECMO longer and be operated upon later. On pre-ECMO blood gas analyses, survivors had higher pH and PaO(2), and lower oxygenation index and PaCO(2) compared with non-survivors. After controlling for covariates, a lower minimum PaCO(2) and side of defect were the only independent predictors of survival. ROC curve for minimum pre-ECMO PaCO(2) had a significant area under the curve (0.72, P=0.003). Survival was 27% in babies unable to achieve a pre-ECMO PaCO(2) <60 mm Hg whereas no patients survived if their lowest pre-ECMO PaCO(2) was >70 mm Hg.

CONCLUSION

Minimum achievable pre-ECMO PaCO(2) is an independent predictor of survival in patients with CDH requiring ECMO life support. These data provide useful prognostic information for counseling families and may facilitate direction of care in extreme cases where the degree of pulmonary hypoplasia may be incompatible with life.

Preliminary observations of the use of high-frequency jet ventilation as rescue therapy in infants with congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Congenital diaphragmatic hernia (CDH) is associated with mortality of 10% to 50%. Several investigators have reported outcomes from centers using high-frequency oscillatory ventilation in their management of CDH, but there are no recent reports on use of high-frequency jet ventilation.

METHODS

During the study period from January 2001 until August 2007, infants with CDH who were cared for at Duke University Medical Center received high-frequency jet ventilation as a rescue mode of high-frequency ventilation. We compared actual survival with predicted survival for infants treated only with conventional ventilation vs those rescued with high-frequency jet ventilation after failing conventional ventilation.

RESULTS

Survival for the 16 infants that received high-frequency jet ventilation was predicted to be 63%; actual survival was 75%. Survival for the 15 infants that received only conventional ventilation was predicted to be 83%; actual survival was 87%. We observed no significant survival benefit for high-frequency jet ventilation, 8.0% (95 confidence interval, -22.0% to 38.1%; P = .59).

CONCLUSIONS

Although our sample size was small, we conclude with consideration of the absolute results, the degree of illness of the infants, and the biologic plausibility for the intervention that high-frequency jet ventilation is an acceptable rescue ventilation mode for infants with CDH.

CONTEMPORARY NEONATAL INTENSIVE CARE MANAGEMENT IN CONGENITAL DIAPHRAGMATIC HERNIA: DOES THIS OBVIATE THE NEED FOR FETAL THERAPY?

The management of congenital diaphragmatic hernia (CDH) in the newborn infant has changed radically since the first successful outcomes were reported 60 years ago. Then it seemed a surgical problem with a surgical solution – do an operation, remove the intestines and solid viscera from the thoracic cavity, repair the defect and allow the lung to expand. CDH in that era was regarded as the quintessential neonatal surgical emergency. The expectation was that urgent surgery would result in improvement in lung function and oxygenation. That approach persisted up to the 1980s when it was realized that the problem was far more complex and involved both an abnormal pulmonary vascular bed as well as pulmonary hypoplasia. The use of systemically delivered pulmonary vasodilator therapy, principally tolazoline, became a focus of interest in the 1980s with small case reports and case series suggesting improved survival. In the 1990s, based on studies that showed worsening thoracic compliance and gas exchange following surgical repair, deferred surgery and pre-operative stabilization became the standard of care. At the same time extracorporeal membrane oxygenation (ECMO) was increasingly used either as part of pre-operative stabilization or as a rescue therapy after repair. Other centres chose to use high frequency oscillatory ventilation (HFOV). Despite all these innovations the survival in live born infants with CDH did not improve to more than 50% in large series published from high volume centres. However, in the past 10 years there has been an appreciable improvement in survival to the extent that many centres are now reporting survival rates of greater than 80%. Probably the biggest impact on this improvement has been the recognition of the role that ventilation induced lung injury plays in mortality and the need for ECMO rescue. This has ushered in an era of a lung protective or “gentle ventilation” strategy which has been widely adopted as a standard approach. While there have been these radical changes in postnatal management attempts have been made to improve outcome with prenatal interventions, starting with prenatal repair, which was abandoned because of preterm labour. More recently there has been increasing experience in the use of balloon occlusion of the trachea as a prenatal intervention strategy with patients being selected based on prenatal predictors of poor outcome. This approach can only be justified if those predictors can be validated and the outcomes (death or serious long term morbidity) can be shown to be better than those currently achievable, namely 80% survival in high volume CDH centres rather than the 50–60% survival frequently quoted in historical papers.

Factors associated with survival in infants with congenital diaphragmatic hernia requiring extracorporeal membrane oxygenation: a report from the Congenital Diaphragmatic Hernia Study Group

OBJECTIVE

To identify factors associated with survival in patients with congenital diaphragmatic hernia (CDH) treated with extracorporeal membrane oxygenation (ECMO).

METHODS

We retrospectively analyzed the data on 3100 patients with CDH in the Congenital Diaphragmatic Hernia Study Group from 82 participating pediatric surgical centers (1995-2004). Covariates considered included prenatal and perinatal clinical information, specifics of surgical repair, and the duration of extracorporeal support.

RESULT

Nine hundred seven patients from the registry were identified as having been both managed with ECMO and undergone attempted surgical repair. The survival rate for the entire Congenital Diaphragmatic Hernia Study Group registry was 67% and 61% for those receiving ECMO in whom repair was attempted (P < .001). Among ECMO-treated children, survivors had a greater estimated gestational age (38 +/- 2 vs 37 +/- 2 weeks; P < .01), greater birth weights (3.2 +/- 0.5 vs 2.9 +/- 0.5 kg; P < .001), were less often prenatally diagnosed (53% vs 63%; P < .01), and were on ECMO for a shorter period of time (9 +/- 5 vs 12 +/- 5 days; P < .001). In logistic regression models, therapy-related variables, including the duration of ECMO, the nature of diaphragmatic repair, and the type of abdominal closure and certain comorbidities, particularly the presence of a concomitant severe cardiac abnormality, were independently associated with outcome.

CONCLUSION

Our model identifies a group of pre-surgical and postsurgical parameters that predict survival rate in patients with CDH on ECMO support. This model was derived from the retrospective data from a large database and will need to be prospectively tested.

The long-term follow-up of patients with a congenital diaphragmatic hernia: a broad spectrum of morbidity

Congenital diaphragmatic hernia (CDH) is a life-threatening anomaly with a mortality rate of approximately 40-50%, depending on case selection. It has been suggested that new therapeutic modalities such as nitric oxide (NO), high frequency oxygenation (HFO) and extracorporal membrane oxygenation (ECMO) might decrease mortality associated with pulmonary hypertension and the sequelae of artificial ventilation. When these new therapies indeed prove to be beneficial, a larger number of children with severe forms of CDH might survive, resulting in an increase of CDH-associated complications and/or consequences. In follow-up studies of infants born with CDH, many complications including pulmonary damage, cardiovascular disease, gastro-intestinal disease, failure to thrive, neurocognitive defects and musculoskeletal abnormalities have been described. Long-term pulmonary morbidity in CDH consists of obstructive and restrictive lung function impairments due to altered lung structure and prolonged ventilatory support. CDH has also been associated with persistent pulmonary vascular abnormalities, resulting in pulmonary hypertension in the neonatal period. Long-term consequences of pulmonary hypertension are unknown. Gastro-esophageal reflux disease (GERD) is also an important contributor to overall morbidity, although the underlying mechanism has not been fully understood yet. In adult CDH survivors incidence of esophagitis is high and even Barrett's esophagus may ensue. Yet, in many CDH patients a clinical history compatible with GERD seems to be lacking, which may result in missing patients with pathologic reflux disease. Prolonged unrecognized GERD may eventually result in failure to thrive. This has been found in many young CDH patients, which may also be caused by insufficient intake due to oral aversion and increased caloric requirements due to pulmonary morbidity. Neurological outcome is determined by an increased risk of perinatal and neonatal hypoxemia in the first days of life of CDH patients. In patients treated with ECMO, the incidence of neurological deficits is even higher, probably reflecting more severe hypoxemia and the risk of ECMO associated complications. Many studies have addressed the substantial impact of the health problems described above, on the overall well-being of CDH patients, but most of them concentrate on the first years after repair and only a few studies focus on the health-related quality of life in CDH patients. Considering the scattered data indicating substantial morbidity in long-term survivors of CDH, follow-up studies that systematically assess long-term sequelae are mandatory. Based on such studies a more focused approach for routine follow-up programs may be established.

Management of congenital diaphragmatic hernia

PURPOSE OF REVIEW

To evaluate the impact of recent research on the management of congenital diaphragmatic hernia in the light of new theories on embryological development, earlier antenatal diagnosis, fetal and postnatal interventions together with advances in perinatal intensive care.

RECENT FINDINGS

The year 2007 provided in excess of 200 publications that address various aspects of congenital diaphragmatic hernia. The genetic basis and the causes of pulmonary hypoplasia at the molecular level are slowly being unravelled. Fetal MRI of lung volume, lung-head ratio, liver position and size of diaphragmatic defect have all been evaluated as early predictors of outcome and with a view to prenatal counselling. The impact of fetal interventions such as fetal endoluminal tracheal occlusion, the mode of delivery, the surgical techniques and agents for treating pulmonary hypertension were evaluated. The influence of associated anomalies and therapeutic interventions on the outcome and quality of life of survivors continue to be appraised.

SUMMARY

Deferred surgery after stabilization with gentle ventilation and reversal of pulmonary hypertension remain the cornerstones of management. Optimal presurgery and postsurgery ventilatory settings remain unproven. Continued improvement in neonatal intensive care raises the bar against which any intervention such as fetal endoluminal tracheal occlusion and extracorporeal membrane oxygenation will be judged.

NKCC-1 and ENaC are down-regulated in nitrofen-induced hypoplastic lungs with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is accompanied by pulmonary hypoplasia and pulmonary hypertension. Fetal lung growth is dependent on the secretion of lung liquid, which normally is absorbed at partus. The ion channel NKCC-1 is involved in this secretory process, but has recently also been reported to be implicated in absorption. CDH patients show a disturbed transition from secretion to absorption. alpha- and beta-ENaC are essential for lung liquid absorption. Common for all transcellular ion transport is the need for Na/K-ATPase as a primary driving force. The aim of the study was first to map the normal pulmonary expression of the above proteins during late gestation and secondly to see if the expression was affected in a CDH rat model. Pregnant Sprague-Dawley rat dams were given nitrofen on gestational day 9.5 to induce CDH. The fetuses were removed on gestational days E18 and E21. In addition, newborn rats were harvested postpartum on day P2. The fetuses were put into one of two groups: hypoplastic lungs without CDH (N-CDH) and hypoplastic lungs with CDH (N+CDH). The pulmonary expression of NKCC-1, alpha-/beta-ENaC and Na/K-ATPase was then analyzed using Western blot. We found that the protein levels of NKCC-1 on gestational days E18 and E21 were significantly lower among fetuses with N+CDH as well as N-CDH compared to controls. The expression of beta-ENaC was also significantly down-regulated in both the groups on E18 and E21. The protein levels of alpha-ENaC and Na/K-ATPase were not found to be significantly decreased, but both showed a tendency towards down-regulation. The marked down-regulation of NKCC-1 in fetal hypoplastic lungs with CDH indicates a possibly decreased lung liquid production. This may be one of the mechanisms behind the disturbed pulmonary development in CDH. We also show that beta-ENaC is down-regulated. Down-regulation of beta-ENaC may result in abnormal lung liquid absorption, which could be one of the mechanisms behind the respiratory distress seen in CDH patients postpartum.

Long-term follow up of infants with congenital diaphragmatic hernia

With improving treatment strategies for congenital diaphragmatic hernia (CDH) infants, an increase in survival of more severely affected patients can be expected. Consequently, more attention is now focused on long-term follow up of these patients. Many reports have emphasized associated morbidity, including pulmonary sequelae, neurodevelopmental deficits, gastrointestinal disorders, and other abnormalities. Therefore, survivors of CDH remain a complex patient population to care for throughout infancy and childhood, thus requiring long-term follow up. Much information has been provided from many centers regarding individual institutional improvements in overall survival. Few of these, however, have reported long-term follow up. The aim of this review is to describe the long-term outcome of survivors with CDH and to suggest a possible follow-up protocol for these patients.

Mechanical ventilation strategies in the management of congenital diaphragmatic hernia

Most infants with congenital diaphragmatic hernia (CDH) require respiratory support. The goal of this report is to present an overview of mechanical ventilation strategies in the management of infants with CDH. The anatomic and physiologic limitations in the lungs of infants with diaphragmatic hernia make decisions on the best strategy and use of mechanical ventilation challenging. We will briefly review lung development in infants with CDH, identifying factors that provide a basis for lung protection strategies. Background on the use of specific mechanical ventilation modes and the rationale for each are provided. Finally, we review mechanical ventilation practices described in published case series of successful CDH management, with a brief review of additional treatments, including inhaled nitric oxide and extracorporeal membrane oxygenation. Although details of a single specific best strategy for mechanical ventilation for CDH infants cannot be identified from current literature, a lung protection ventilation approach, regardless of the device used, appears to reduce mortality risk.

Pulmonary function and exercise testing in adult survivors of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is accompanied by pulmonary hypoplasia and structural abnormalities of the pulmonary vascular bed. It is unknown whether pulmonary function, exercise capacity, and gas exchange during exercise are impaired in adult CDH survivors. The objective of this study was to assess the long-term pulmonary function, exercise capacity, and gas exchange during exercise and relate these findings with quality of life. Of the 23 patients eligible for this study, 12 adult CDH survivors (mean age, 24.3 +/- 4.1 years) with high-risk CDH agreed to participate. Pulmonary function tests, diffusion capacity, and a cardiopulmonary exercise test (CPET) were performed. The FEV1 (mean z-score +/- SD; -1.30 +/- 1.37), FEF25-75% (-1.49 +/- 1.14), and the KCO (-1.03 +/- 1.24) were found to be lower in CDH survivors. The RV/TLC ratio (28.2% +/- 5.0%) was found to be higher. Despite these abnormalities, percent predicted work load (102% +/- 17.2%) and percent predicted maximal oxygen uptake (90.8% +/- 18.9%) were normal in most of the patients. The quality of life of CDH survivors, assessed with the SF-36 questionnaire, is comparable to the general population. Comparison of participants to non-participants did not reveal significant differences in clinical characteristics. In this first study assessing pulmonary function in adult survivors of CDH, mild airway obstruction was observed in most of the patients together with a slightly reduced diffusion capacity for CO. Exercise capacity and gas exchange parameters were normal in this group, indicating that patients do not have a physical impairment, as reflected by a normal quality of life of CDH patients.

Lung function in infants after repair of congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Congenital diaphragmatic hernia (CDH) is initially characterized by severe restrictive lung defect and low lung compliance, but survivors have relatively few abnormalities later in life. We studied the changes in lung growth and function in infants after the repair of CDH.

METHODS

Retrospective analysis of pulmonary function tests was performed during the first 24 months of life in 56 infants (33 male and 23 female) after repair of CDH. Lung function (functional residual capacity [FRC], respiratory system compliance [C(rs)] and resistance [R(rs)], and maximum expiratory flow rate at FRC [V'(maxFRC)]) were compared among 4 different ages (0-3, 4-6, 7-12, and 13-24 months).

RESULTS

All indices of lung function (mean +/- SD of z scores) were abnormal during the first 6 months of life but were almost normalized by 24 months (P < .0001): FRC, from -0.84 +/- 0.5 to 3.26 +/- 2.07; C(rs), from -0.87 +/- 0.4 to 1.84 +/- 1.75; R(rs), from 2.85 +/- 2.71 to -0.23 +/- 2.03, and V'(maxFRC), from -1.63 +/- 0.4 to -0.09 +/- 0.94. There was significant correlation (P < .001) between lung function and increase in age, height, and especially weight.

CONCLUSIONS

Lung growth and function gradually normalize between 6 and 24 months of life after repair of CDH.

Long-term follow-up of patients with high-risk congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Recent advances including prenatal diagnosis, high-frequency oscillatory ventilation, and nitric oxide inhalation therapy have gradually improved the survival of high-risk congenital diaphragmatic hernia. However, the factors affecting the long-term outcome of these patients have not been well established.

METHODS

Thirty-three children with ages 4.1 +/- 2.5 years underwent clinical examination including growth measurements, echocardiography, ventilation, and perfusion scintigraphy.

RESULTS

No late death was observed. Common complications were frequent respiratory tract infection (13 patients) and bowel obstruction (5 patients underwent surgery). Although frequent respiratory tract infection decreased with increasing age, patients with frequent respiratory tract infection had a decreased uptake of lung ventilation and perfusion scintigraphy on the affected side and had a decreased height for age and weight for height. No significant difference in lung ventilation and perfusion scintigraphy was observed between patients treated with and without extracorporeal membrane oxygenation, those requiring oxygen more than 1 month, and between those with and without prenatal diagnosis. Patients with a patch repair had decreased uptake on lung perfusion scintigraphy. Although frequent respiratory tract infection may be owing to hypoplasia of the ipsilateral lung, it may impair recovery of the hypoplastic lung.

CONCLUSION

These results indicate that monitoring for respiratory tract infection in addition to nutritional assessment should be required in the follow-up of patients with congenital diaphragmatic hernia at high risk.

Fetal tracheal occlusion in lambs with congenital diaphragmatic hernia: role of exogenous surfactant at birth

Fetal tracheal occlusion (TO) has been used to reverse the lung hypoplasia associated with congenital diaphragmatic hernia (CDH). However, TO has a detrimental effect on type II pneumocyte function and surfactant production. Previously, we have shown that in surgically created CDH lambs, TO improved markedly the response to resuscitation even though the lungs remain surfactant deficient. The goal of this investigation was to assess the effects of exogenous surfactant administered at birth to CDH lambs with or without fetal TO during 8 h of resuscitation. Lambs were divided into five groups: CDH, CDH+surfactant (SURF), CDH+TO, CDH+TO+SURF, and nonoperated controls. A left-sided CDH was created in fetal lambs at 80 d gestation. TO was performed at 108 d, and the lambs were delivered by hysterotomy at 136 d. Bovine lipid extract surfactant was administered before the first breath and again at 4 h of life. All CDH+SURF lambs, but only three of five CDH lambs, survived up to 8 h. When compared with the corresponding nonsurfactant-treated group, surfactant-treated CDH and CDH+TO lambs did not demonstrate improved alveolar-arterial oxygen gradients, pH, or Pco(2). In fact, in the CDH+TO group, surfactant treatment significantly worsened ventilation efficiency as measured by the ventilation efficiency index. The observed improvement in pulmonary compliance secondary to surfactant treatment was not significant. This investigation demonstrates that prophylactic surfactant treatment at birth does not improve gas exchange or ventilation efficiency in CDH lambs with or without TO.

Effect of lung hypoplasia on birth-related changes in the pulmonary circulation in sheep

Lung hypoplasia (LH) is a serious cause of neonatal compromise, but little is known of its functional effects on the pulmonary circulation. Our aim was to characterize birth-related changes in the pulmonary circulation of newborn lambs with LH and to compare them with alterations in respiratory function. LH was induced in six ovine fetuses by the creation of a tracheo-amniotic shunt as well as amniotic fluid drainage starting at 105.6+/-1.5 (mean+/-SEM) days of gestation (term approximately 147 d). At 139.9+/-0.3 d, fetuses were exteriorized under anesthesia to implant vascular catheters and an ultrasonic flow probe around the left pulmonary artery. The lambs then were delivered and ventilated for 2 h, during which systemic and pulmonary artery pressures, left pulmonary blood flow, and measures of respiratory function were recorded. At autopsy, lungs were weighed and volume was measured at 20 cm H2O. In LH lambs, lung weight was 25% lower and respiratory system compliance was 30% lower than in controls. Mean pulmonary blood flow in LH lambs was 42% lower and pulmonary vascular resistance was 138% higher than in controls. Morphometry showed that volume density of pulmonary arteries in LH was 30% lower than in controls. We conclude that, in this LH model, changes in ventilatory indices were proportional to the change in lung size, whereas changes in the pulmonary circulation were greater than the change in lung size and were associated with reduced density of pulmonary arteries. LH severely impairs normal adaptation of the pulmonary circulation in the perinatal period.

Survival of severe congenital diaphragmatic hernia has morbid consequences

BACKGROUND/PURPOSE

Fetal tracheal occlusion (TO) was developed in an attempt to enhance prenatal lung growth and improve survival in fetuses with severe congenital diaphragmatic hernia (CDH). We conducted a randomized, controlled clinical trial in 24 fetuses with severe left CDH (liver herniated into the thorax and low lung-to-head ratio) to compare survival after endoscopic fetal TO vs standard perinatal care (control) and prospectively followed up the 16 survivors (9 control, 7 TO) to compare neurodevelopmental, respiratory, surgical, growth, and nutritional outcomes.

METHODS

At 1 and 2 years old, subjects underwent evaluation consisting of medical and neurological history and physical, developmental testing, nutritional assessment, oxygen saturation and pulmonary function testing, chest radiograph, and echocardiogram. Growth and developmental measures were corrected for prematurity. Data were analyzed by Mann-Whitney rank sum test, Fisher's Exact test, and logistic and linear regression.

RESULTS

Infants with TO were significantly more premature at birth (control vs TO, 37.4 +/- 1.0 vs 31.1 +/- 1.7 weeks; P < .01). Growth failure ( z score for weight <2 SDs below mean) was severe in both groups at 1 year of age (control vs TO, 56% vs 86%; P = .31). There was considerable catch-up growth by age 2 years (growth failure: control vs TO, 22% vs 33%; P = .19). There were no differences in other growth parameters. There were also no differences in neurodevelopmental outcome at 1 and 2 years. Supplemental oxygen at hospital discharge was a significant predictor of worse neurodevelopmental outcome at 1 and 2 years old (P = .05 and P = .02, respectively). Hearing loss requiring amplification has been diagnosed in 44% of the group (control vs TO, 44% vs 43%; P = 1.0).

CONCLUSIONS

In this group of infants with severe CDH, there were no differences in outcome at 2 years old despite significant prematurity in the TO group. Oxygen supplementation at hospital discharge identified the most vulnerable group with respect to neurodevelopmental outcome, but all infants had significant growth failure, and hearing impairment is a substantial problem in this population. Severe CDH carries significant risk of chronic morbidity.

Infant pulmonary function in a randomized trial of fetal tracheal occlusion for severe congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) carries a high mortality risk secondary to pulmonary hypoplasia and respiratory failure. In experimental animals, fetal tracheal occlusion (TO) induces lung growth and morphologic maturation. We measured indicators of pulmonary function in 20 infants who were enrolled in a randomized trial of fetal TO as treatment for severe CDH [nine with conventional treatment (controls); 11 with TO]. We hypothesized that TO would improve lung function. At birth, the TO group had a lower mean gestational age (30.8 +/- 2.0 versus 37.4 +/- 1.0 wk; p=0.0002). All infants required assisted ventilation. Mortality did not differ between groups (64 versus 78%, TO and control, respectively; p=0.64). We measured respiratory mechanics at four study points: 1) first 24 h, 2) before CDH operative repair (5.9 +/- 2.2 d), 3) immediately after repair (7.0 +/- 2.2 d), and 4) before elective extubation (32.5 +/- 16.1 d). We calculated perioperative oxygenation index and alveolar-arterial oxygen difference to assess efficiency of pulmonary gas exchange. Data were analyzed by univariate and repeated measures techniques. Respiratory system compliance (Crs) was low. The rate of increase in Crs over the four study points was greater in the TO group than in control subjects. Crs in the TO group was significantly greater at study 2 (0.28 +/- 0.12 versus 0.17 +/- 0.04 mL.cm H2O(-1).kg(-1); p=0.02) and study 4 (0.93 +/- 0.45 versus 0.51 +/- 0.16 mL.cmH2O(-1).kg(-1); p=0.02). oxygenation index did not differ between groups, but alveolar-arterial oxygen difference was lower in the TO infants. We conclude that fetal TO for severe CDH results in modest improvements in neonatal pulmonary function that are of questionable clinical significance.

Extralobar sequestration with congenital diaphragmatic hernia: a complicated case study

This article presents a case study of an infant (JG) with an antenatal diagnosis of a left diaphragmatic hernia and an extralobar sequestration of his right lung, which was noted postnatally. JG's course was complicated by persistent pulmonary hypertension of the newborn (PPHN) and suspected pulmonary hypoplasia, and he required support with extracorporeal life support (ECLS). JG's case was unusual in his presentation of extreme PPHN that was unresponsive to inhaled nitric oxide and ECLS. His PPHN was nearly intractable, requiring treatment with vasodilators combined with intravenous sildenafil, which had never been tried in our institution before this case. The article concludes with a discussion of the etiology, diagnosis, and management of congenital diaphragmatic hernia and extralobar sequestration, singly and in combination.

Respiratory characteristics of infants with pulmonary hypoplasia syndrome following preterm rupture of membranes: a preliminary study for establishing clinical diagnostic criteria

BACKGROUND

At present, the diagnosis of pulmonary hypoplasia is based on postmortem findings, and there are no clear clinical diagnostic criteria to facilitate its identification and management.

AIM

To characterise the respiratory status of pulmonary hypoplasia syndrome (PHS) following preterm rupture of membranes so as to establish its clinical diagnostic criteria.

STUDY DESIGN

Retrospective comparison of respiratory characteristics of six typical PHS infants with six wet lung syndrome (WLS) infants who served as controls.

SUBJECTS

The PHS and WLS infants were selected from 1094 patients admitted to a tertiary care neonatal unit over a 6-year period, with criteria based on perinatal history, respiratory signs, X-ray and laboratory findings, and ventilator settings.

OUTCOME MEASURES

The compared variables were lung volume index (LVI) calculated from lung dimensions on chest X-ray, ventilatory index (VI), ventilatory efficiency index (VEI), response to artificial surfactant treatment, and ventilation days.

RESULTS

In PHS compared to WLS infants, LVI was lower (4.5 +/- 0.5 vs. 9.5 +/- 1.5; p < 0.01), VI was higher (0.108 +/- 0.030 vs. 0.022 +/- 0.005; p < 0.05), and VEI was lower (0.083 +/- 0.012 vs. 0.258 +/- 0.052; p < 0.01) (mean +/- S.E.). Artificial surfactant was given to four PHS infants, but none of them showed respiratory improvement. Ventilation days were 11-79 in three surviving PHS infants and 2-14 in WLS infants.

CONCLUSIONS

In this preliminary study, low LVI (< 6.5) and VEI (< 0.15) were the most useful indicators of PHS.

Neonatal anesthesia

The physiology of the preterm and term neonate is characterized by a high metabolic rate, limited pulmonary, cardiac and thermoregulatory reserve, and decreased renal function. Multisystem immaturity creates important developmental differences in drug handling and response when compared to the older child or adult. Neonatal anesthetic management requires an understanding of the pharmacophysiologic limitations of the neonate as well as the pathophysiology of coexisting surgical disease. This review addresses the pertinent aspects of neonatal physiology and pharmacology, general considerations in the anesthetic care of surgical neonates, and concludes with a brief review of the anesthetic management of neonates with necrotizing enterocolitis, diaphragmatic hernia, and tracheoesophageal fistula.

Cardiopulmonary anatomy and function in long-term survivors of mild to moderate congenital diaphragmatic hernia

BACKGROUND/PURPOSE

In the last decades, several studies regarding cardiopulmonary sequelae in survivors of congenital diaphragmatic hernia (CDH) have been published, but results often are conflicting, and controversies still exist. The aim of this study was to assess cardiopulmonary anatomic and functional outcome in a group of long-term survivors of CDH of mild to moderate degree.

METHODS

Twenty-four children aged 8.15 +/- 2.80 years underwent clinical examination with growth assessment, chest radiographs, echocardiography, pulmonary perfusion scintigraphy, static lung volumes measurement, and spirometry.

RESULTS

Mean Z scores of weight for age and height for age were within normal values. Echocardiography showed normal anatomy and function in all but 3 patients with isolated CDH, in whom minor alterations were detected. Mean perfusion to the affected side was significantly lower (45.16 +/- 5.30%; P <.0001) but still within normal range. Four children showed a substantial impairment of perfusion to the hernia side. The mean spirometric values and pulmonary volumes were normal. However, a mild restrictive pattern was evident in 6 children (27.3%), an obstructive pattern in 3 (13.6%), and a mixed obstructive and restrictive impairment in 1.

CONCLUSIONS

Hypoplastic lungs of mild to moderate CDH survivors continue to cause pulmonary morbidity in some children many years after the correction of the defect. In particular, lung perfusion appears to be impaired in 20% of the patients and pulmonary function in 45%, without any significant cardiac or developmental sequelae. The negative correlation between FEV1 and duration of ventilation at presentation (r = -0.49; P =.026) may be caused by the consequences of lung hypoplasia, but initial ventilatory management may contribute to increased pulmonary morbidity. Relationship between perfusion and FEF25-75 (r = 0.61; p = 0.004) could reflect an equivalent degree of reduction in the caliber of distal airways and pulmonary vascular tree.

Long-term outcome following extracorporeal membrane oxygenation for congenital diaphragmatic hernia: the UK experience

OBJECTIVE

We evaluated the long-term outcome of neonates receiving extracorporeal membrane oxygenation (ECMO) for congenital diaphragmatic hernia (CDH). Study design A retrospective review of all 73 neonates with CDH supported with ECMO in the United Kingdom between 1991 and 2000, with follow-up to January 2003. Information was from hospital charts and from communication with family doctors and pediatricians. Median follow-up period for survivors was 67 months.

RESULTS

46 infants (63%) were weaned from ECMO, 42 (58%) survived to hospital discharge, and 27 (37%) survived to age 1 year or more. A higher birth weight, higher 5-minute Apgar score, and postnatal diagnosis were "pre-ECMO" predictors of long-term survival. Comorbidity was common in long-term survivors: 13 (48%) had respiratory symptoms, 16(59%) had gastrointestinal problems, and 6 (19%) had severe neurodevelopmental problems. Only 7 children were free of significant neurodevelopmental deficit and required no further medical or surgical intervention.

CONCLUSION

Using the current referral criteria, ECMO can be used to support the sickest neonates with CDH. However, there is significant mortality in the first year of life, and long-term physical and neurodevelopmental morbidity remains in the majority of survivors.

Congenital diaphragmatic hernia: advances in prenatal therapy

Despite intensive clinical and experimental efforts, mortality from CDH remains high. More than two decades of research in multiple centers has led to a better understanding of the pathophysiology, prognosis, and treatment options for fetuses that have CDH. It now appears that fetuses that have prenatally diagnosed CDH can be stratified into high- and low-risk groups based upon sonographic parameters. Fetuses that do not have liver herniation into the chest that have a favorable LHR have an excellent chance of survival with postnatal therapy. Prenatal diagnosis allows the time and place of delivery to be planned in advance so these infants can be treated in a tertiary care nursery that has maximal medical and surgical therapy. Fetuses that have liver herniation into the chest and an unfavorable LHR have a grim prognosis. These fetuses might benefit from in utero intervention. There is no role for open fetal repair of the diaphragmatic detect; however, fetoscopic temporary tracheal occlusion might improve lung growth and development and might decrease morbidity and mortality in these infants. The FETENDO strategy appears to work, and for the first time it offers hope to the fetus that has high-risk CDH, but its efficacy must be proven in a proper randomized, controlled trial.

Fetal pulmonary artery diameters and their association with lung hypoplasia and postnatal outcome in congenital diaphragmatic hernia

OBJECTIVE

We hypothesized that fetal branch pulmonary artery (PA) diameters indirectly reflect lung mass and are associated with postnatal outcome in cases of isolated congenital diaphragmatic hernia (CDH).

STUDY DESIGN

We retrospectively reviewed echocardiograms of fetuses with CDH, measuring branch PA diameters and other echocardiographic parameters. Antenatal parameters were correlated with postmortem lung weights in 5 fetuses after pregnancy termination. Fetal echocardiographic measures were correlated with outcome variables in 29 live-born infants with CDH to identify antenatal indices associated with postnatal death and respiratory morbidity.

RESULTS

Antenatal branch PA size correlated with postmortem lung weights from 5 terminated fetuses (r = 0.87). In 26 cases of left CDH in which the fetus continued to term, the ipsilateral branch PA diameter was significantly smaller than the contralateral branch PA diameter at presentation (P <.001). In these fetuses, a larger contralateral PA diameter was associated with worse postnatal survival (P =.049). Among survivors with left CDH, the main PA z score and the discrepancy between right and left PA diameters correlated positively with duration of supplemental oxygen requirement (P =.019 and P =.022, respectively) and ventilation (P =.036 and P =.012, respectively). Serial antenatal studies in 8 of 10 cases revealed progressive ipsilateral PA hypoplasia.

CONCLUSION

Antenatal branch PA size correlates with postmortem lung weight. A larger contralateral PA, and significant branch PA discrepancy and larger main PA diameter, best correlate with postnatal death and respiratory morbidity, respectively. Progressive ipsilateral PA hypoplasia suggests progressive in utero lung hypoplasia in cases of CDH.

Down-regulation of regulatory proteins for differentiation and proliferation in murine fetal hypoplastic lungs: altered mesenchymal-epithelial interactions

We compared proliferation (growth) and differentiation (development) related proteins in normal and hypoplastic fetal murine lungs. The hypoplastic lungs were created in CD-1 fetal mice by nitrofen exposure (25 mg per pregnant mouse given intragastrically on gestational day 8 [Gd8]), as published earlier. The lungs were harvested at Gd14, 16, 19 and from neonates. Immunoblot analyses were carried out for transcription factors (oncogenic proteins, nuclear receptor, and transmembrane receptor proteins) in severely hypoplastic murine fetal lungs with coexistent diaphragmatic hernia, and results were compared with those derived from normal lungs of equivalent age. These proteins have proposed roles in the regulation of proliferation and differentiation processes of fetal lungs. We have shown that the product of the oncogene c-myc was reduced in hypoplastic lungs at all stages of gestation, whereas c-Fos protein levels were variable. These proteins are known to regulate transcription of various developmental proteins, such as those responsible for proliferation and differentiation. Further, the nuclear transcription factors thyroid transcription factor-1 (TITF-1) and glucocorticoid receptor (GR) were reduced, and thyroid hormone receptor (TR) and retinoic acid receptors (RARs) were inhibited in severely hypoplastic lungs compared to normal lungs of equivalent gestational stage, except in neonatal lungs, where signals for RARs were seen. TITF-1 is known to localize in bronchial epithelial cells in developing lungs. It is restricted to type II pneumocytes with gestational development in the normal lungs and regulates surfactant proteins. Earlier, we have reported that surfactant proteins are reduced in hypoplastic lungs. In the current study, reduced GR and TITF-1 proteins may play a role in reducing surfactant proteins in the hypoplastic lungs. The significant inhibition in TR and RARalpha in the severely hypoplastic lungs reflects on affected epithelial cell maturation and alveolar formation, respectively. Altered RARbeta levels correlate with affected lung growth and branching morphogenesis of nitrofen-exposed lungs. A transmembrane receptor protein EGFR was reduced in hypoplastic lungs, suggesting the involvement of altered mesenchymal-epithelial signal transduction pathways. We conclude (1) Our data suggest altered levels of various nuclear transcription factors in the murine fetal hypoplastic lungs; (2) Reduced levels TITF-1 protein in hypoplastic lungs may have caused the functional immaturity of distal lung, immature airways and thus may affect overall differentiation of lungs. These results correlated with low levels of surfactant proteins in these lungs; (3) TR and RAR inhibition indicate their roles through reduced or retarded proliferation and differentiation processes in the severely hypoplastic lungs; (4) GR down-regulation in developing fetal murine hypoplastic lungs indicate delayed development, and GR up-regulation in affected neonates may be induced by stress/stretch caused at birth due to air-breathing; (5) Down- regulation of EGFR indicate altered mesenchymal-epithelial interactions and possible influence on lung proliferation and differentiation.