Congenital diaphragmatic hernia: predictors of severity in the ECMO era

Experimental fetal tracheal ligation prevents the pulmonary hypoplasia associated with fetal nephrectomy: possible application for congenital diaphragmatic hernia

Pulmonary hypoplasia has a definite clinical impact in a variety of congenital diseases such as renal dysplasia and congenital diaphragmatic hernia. These diseases have in common inadequate growth and development of fetal lungs. Previous reports have demonstrated increased lung growth with in utero tracheal ligation. The purpose of this study was to determine if lung growth can be accelerated in the setting of experimental pulmonary hypoplasia. Ninety-five-day gestation fetal sheep were divided into four experimental groups: nephrectomy, nephrectomy with tracheal ligation, tracheal ligation alone, and sham-operated control animals. Animals were delivered near term and their lungs inflation fixed at 25 cm H2O. Total alveolar number (Alv#), total alveolar surface area (AlvSA), and lung volume to body weight ratios (LV:BW) were determined for apical and basilar segments of each animal and then averaged. Total lung DNA and protein content were also analyzed. The nephrectomy group had smaller lungs than control animals with decreased Alv#, AlvSA, and LV:BW. In contrast, nephrectomy with tracheal ligation produced large lungs which had increased Alv#, AlvSA, and LV:BW when compared with both the nephrectomy and the control group (P < .01). Total lung DNA and protein concentrations were both markedly elevated in the tracheally obstructed groups. However, the DNA/protein ratios remained constant in all four groups, suggesting that lung growth had occurred through cell multiplication. Photomicrographs of the lung demonstrated a histologically immature appearance in the nephrectomy group and a histologically mature appearance in the tracheally obstructed groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Correction of congenital diaphragmatic hernia in utero: VI. Hard-earned lessons

Extensive experimental work suggests that repair of congenital diaphragmatic hernia (CDH) in utero may salvage severely affected fetuses who otherwise have a high expected mortality despite optimal postnatal care including extracorporeal membrane oxygenation (ECMO). We have reported that repair of CDH in utero is physiologically sound and safe for the mother, but technically difficult especially when the liver is herniated into the fetal chest. In the 3 years since our last report (1989 to 1991), 61 additional patients were referred for consideration of in utero repair. Fetal repair was attempted in 14 with severe isolated left CDH diagnosed before 24 weeks gestation. Five fetuses died intraoperatively, from technical problems related to reduction of incarcerated liver and uterine contractions--problems which have subsequently been surmounted. Nine patients were successfully repaired. Four babies survived, two delivered prematurely and died, and three died in utero within 48 hours of repair. Intraoperative technical problems have been overcome; the factors limiting successful outcome are postoperative physiologic management of the maternal-fetal unit and effective tocolysis to control preterm labor.

Intratracheal pulmonary ventilation and congenital diaphragmatic hernia: a report of two cases

Previous studies from our institution have shown that neonates with congenital diaphragmatic hernia (CDH), whose best postductal PaO2 (BPDPO2) was less than 100 mm Hg while on maximal conventional mechanical ventilation (CMV), had a mortality exceeding 90%. When combined with extracorporeal membrane oxygenation (ECMO), the mortality rose to 100% in those infants who developed hypercarbia following decannulation. Historically, those patients have required increasing ventilator support, leading to iatrogenic lung damage, and eventual death. Intratracheal pulmonary ventilation (ITPV) using the reverse thrust catheter (RTC) developed by Kolobow incorporates a continuous flow of humidified gas through a reverse Venturi catheter positioned at the distal end of the endotracheal tube. In animal studies, ITPV was shown to result in a reduced physiological dead-space (VD), to facilitate expiration, and to enhance CO2 elimination. In our current study, we have applied ITPV in two neonates with CDH who could not be weaned from ECMO because of uncontrollable hypercapnia, and who met above criteria for 100% mortality. In both cases, ITPV restored normal PaCO2 at low peak inspiratory pressure (PIP) with a substantial decrease in VD. We believe ITPV is suited to ventilating newborns with CDH in whom barotrauma is known to be common. Beyond its present use, ITPV may be useful to ventilate children with other forms of respiratory failure, and should be so considered along with other now available methods of mechanical pulmonary ventilation.

Congenital diaphragmatic hernia in an era of delayed repair after medical and/or extracorporeal membrane oxygenation stabilization: a prognostic and management classification

In November 1987 we began to practice delayed repair of acutely symptomatic congenital diaphragmatic hernia (CDH) following medical and/or extracorporeal membrane oxygenation (ECMO) stabilization. We reviewed 23 consecutive patients with CDH symptomatic at birth treated over the ensuing 2 1/2 years. The mean age at admission, age at repair, and interval from admission to repair were 4.9, 37.0, and 32.6 hours, respectively. Overall survival was 52% (12/23). ECMO was used in 14 patients with 7 survivors (50%); 4 of these patients underwent repair prior to ECMO and 10 while on ECMO. The patients were retrospectively grouped into three classes based on postductal arterial blood gas (ABG) response to conventional medical management: class A (n = 8), able to achieve and sustain adequate oxygenation (PO2 greater than 60 mm Hg) and hyperventilation (PCO2 less than 40 mm Hg); class B (n = 10), unable to sustain adequate oxygenation (PO2 less than 60 mm Hg) but able to be hyperventilated (PCO2 less than 40 mm Hg); and class C (n = 5), unable to be oxygenated (PO2 less than 60 mm Hg) or hyperventilated (PCO2 greater than 40 mm Hg). The interval from admission to repair was 13.6, 53.5, and 25.4 hours for classes A, B, and C, respectively. Two class A (25%), nine class B (90%), and three class C patients (60%) were placed on ECMO. Survival rates were 88%, 50%, and 0% for classes A, B, and C, respectively. We propose the following management protocol. Class A patients are stable and can be repaired at any convenient point after admission without prerepair ECMO; few will need it afterward.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary growth and remodeling in infants with high-risk congenital diaphragmatic hernia

Infants born with congenital diaphragmatic hernia (CDH) have pulmonary hypoplasia, but the pattern of postnatal growth in these lungs has not been documented. The lungs of 21 children dying with CDH were analyzed to determine how the pulmonary morphology changed with age. The patients were stratified into three age groups for ANOVA analysis (less than 8 days, 8 to 21 days, greater than 21 days). Morphometric techniques previously described were used. Lung volume and weight as well as pulmonary artery length and diameter increased with age (P = .04), whereas the number of airway generations was similar for each group. Radial alveolar number also increased, particularly in the contralateral lung (P = .02). The percentage of intraacinar artery muscularization decreased with age (P = .02), while larger intraacinar arteries showed a nonmuscular structure, again particularly in the contralateral lung (P = .004). It is concluded that: (1) significant lung growth does occur postnatally at the alveolar level after CDH repair; and (2) there is postnatal vascular remodelling resulting in larger and less muscular arteries. These changes should contribute to a decrease in pulmonary arterial hypertension over time. However, the time period over which these changes occur exceeds the current limitations of invasive support measures such as extracorporeal membrane oxygenation. Elucidation of the factors responsible for this growth could result in new therapeutic strategies to enhance or accelerate postnatal pulmonary development in infants with CDH.

Delayed repair and preoperative ECMO does not improve survival in high-risk congenital diaphragmatic hernia

It has been suggested that delayed repair with preoperative stabilization might improve survival in high-risk (symptomatic within 6 hours of birth) congenital diaphragmatic hernia (CDH). This study compares the results of immediate operation versus delayed repair using extracorporeal membrane oxygenation (ECMO) when necessary. Since we first used ECMO in 1984, 101 high-risk CDH infants have been treated. Prior to 1987, we used immediate repair and postoperative ECMO if necessary. Between 1987 and 1990 we combined delayed operation (24 to 36 hours) with preoperative ECMO as necessary. No infant in this series was excluded from ECMO therapy unless absolute contraindications existed (prematurity, intracranial hemorrhage, or other major anomalies). Fifty-five patients received immediate operation and 46 had delayed repair. The two groups were comparable populations based on gestational age, birth weight, age at onset of symptoms, Apgar scores, best postductal PO2 (BPDPO2), and frequency of antenatal diagnosis. There was no statistically significant difference in overall survival between the two groups. Differences in survival among subpopulations (BPDPO2 greater than 100 or less than 100, antenatal diagnosis, inborn v outborn) also are not significant. The requirement for ECMO was similar in both groups. Survivors in the delayed repair group were ventilated longer and on ECMO longer, but had fewer late deaths (greater than 21 days) and fewer pulmonary sequelae (O2 dependency at discharge) than infants in the immediate repair group (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)