Survival in neonatal congenital hernia without extracorporeal membrane oxygenation support

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.

Congenital Diaphragmatic Hernia Repair on Extracorporeal Life Support: A Decade of Lessons Learned

Congenital diaphragmatic hernia (CDH) is a vexing anomaly that manifests with variable pulmonary compromise in neonates. More than one-third of neonates with CDH require extracorporeal membrane oxygenation (ECMO) for refractory pulmonary hypertension (PHN). To assess the outcome of neonates having CDH repair on ECMO, we reviewed our experience for babies treated between 1992 and 2003. Of 97 neonates with CDH, 40 required ECMO, and 30 were repaired on bypass. Eighteen were supported by veno-venous bypass (VV) and 12 by veno-arterial bypass (VA). While on ECMO, transfusion requirements increased twofold postoperatively (15 to 33 cc · kg-1 · day-1, P = 0.03) and then significantly decreased after decannulation (1.5 cc · kg-1 · day-1, P < 0.01). Non-intracranial hemorrhage occurred in 7 (23%) infants and intracranial hemorrhage in 3 (10%). Twelve (40%) infants died; one (3%) on ECMO secondary to refractory PHN. The mean length of stay for the 18 (60%) survivors was 48 days. Comparisons between survivors and nonsurvivors showed a significantly increased mortality for infants placed on VA bypass ( P < 0.01). However, no other variable was predictive of survival. We conclude that CDH repair on ECMO is technically feasible, shows similar survival to the Extracorporeal Life Support Organization (ELSO) registry, and is associated with few bleeding complications.

A statistical model to predict nonsurvival in congenital diaphragmatic hernia

OBJECTIVE

To develop a predictive model using echocardiographic indices to identify nonsurvivors from survivors in preoperative patients with congenital diaphragmatic hernia (CDH).

STUDY DESIGN

Eight cases of CDH, with a mortality rate of 38%, underwent echocardiographic study before surgical repair. Left ventricular mass (LVMASS) using the area-length method of Wyatt et al. and fractional shortening (FS) by M-mode measurements were determined.

RESULTS

We identified a nonlinear nonoverlapping distribution that predicted nonsurvivors from survivors, p=0.04. Multiple regression analysis demonstrated the quantity (LVMASS x FS)(1/2) to be correlated with nonsurvival with a coefficient of determination r(2)=0.55. Comparison of the means of the quantity (LVMASS x FS)(1/2) for the two groups suggested two distinct populations, p=0.04.

CONCLUSION

The mathematical quantity (LVMASS x FS)(1/2) calculated from echocardiographic measurements obtained preoperatively in babies with CDH may predict nonsurvival despite maximal intervention.

Congenital diaphragmatic hernia: a meta-analysis of mortality factors

PURPOSE

The aim of this study was to review all available studies reported in the English-language literature from 1975 through 1998, and by meta-analysis assess the importance of prenatal diagnosis, associated malformations, side of hernia, timing of surgery, and study population on mortality rates in patients with congenital diaphragmatic hernia (CDH).

METHODS

One-hundred-two studies were identified, and 51 studies (2,980 patients) fulfilled the prespecified inclusion criteria. Studies were grouped according to study population into: (I) fetuses diagnosed prenatally; (II) neonates admitted to a treatment center; and (III) population-based studies.

RESULTS

Pooled total mortality rate was significantly higher in category I than in category III (75.6% v 58.2%, P < .001). Pooled hidden postnatal mortality rate (deaths before admittance to a treatment center) in population-based studies was 34.9%. Prenatally diagnosed patients in both category II and III had significantly higher mortality rates than those diagnosed postnatally. Mortality rates were significantly higher among CDH infants with associated major malformations compared with isolated CDH in all 3 categories. An increased mortality rate in right-sided CDH was found in category II and III.

CONCLUSIONS

Prenatal diagnosis of CDH, presence of associated major malformations, and the study population have a major influence on mortality rate. The very high mortality rate in studies of fetuses with a prenatal diagnosis of CDH should be taken into account in prenatal counselling.

Does extracorporeal membrane oxygenation improve survival in neonates with congenital diaphragmatic hernia? The Congenital Diaphragmatic Hernia Study Group

BACKGROUND/PURPOSE

The benefit of extracorporeal membrane oxygenation (ECMO) in improving survival of neonates with congenital diaphragmatic hernia (CDH) has never been clearly demonstrated. This may be due to comparisons made between treatment groups of unequal illness severity and the low statistical power of analyses from previous studies. The authors analyzed the data from the multicenter CDH registry to determine if ECMO improves survival in CDH neonates with a high risk of mortality.

METHODS

A total of 730 neonates were enrolled in the CDH Registry from January 1995 to November 1997. Of these, 632 neonates had a complete data set and were eligible for ECMO by the weight criterion of greater than 2.0 kg. Multivariate logistic regression analysis was used to assess mortality risk for each neonate based on previously validated independent predictors of survival: birth weight and 5-minute Apgar. Five quintile groups were defined based on increasing predictive mortality risk. Multivariate logistic regression and chi2 analyses with birth weight, Apgar score at 5 minutes, and predictive mortality risk as covariates were then performed to assess survival benefit of ECMO compared with conventional therapy alone. Patient survival rate was defined as survival to discharge from hospital.

RESULTS

When analyzing all 632 neonates, ECMO neonates (n = 289) had a decidedly lower survival rate (52.9% v 77.3%, P< .001) than non-ECMO neonates (n = 343) without standardizing for the degree of illness. However, when taking into account the patients' predictive mortality risk, ECMO was associated with improved survival in the neonates with mortality risk < or = 80% (P < .05). Furthermore, ECMO was shown to be a positive independent predictor of survival when accounting for the covariates of birth weight, 5-minute Apgar, and mortality risk (P < .05).

CONCLUSIONS

ECMO significantly improves survival rates for those CDH neonates with a predictive mortality risk > or = 80%. Generally, the more critically ill the patient with CDH, the more marked the survival benefit obtained.

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

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