Experience with abdominal wall closure for patients with congenital diaphragmatic hernia repaired on ECMO

Surgical approaches to congenital diaphragmatic hernia

Surgical repair of the diaphragm is essential for survival in congenital diaphragmatic hernia (CDH). There are many considerations surrounding the operation - why the operation matters, optimal timing of repair and its relation to extracorporeal life support (ECLS) use, minimally invasive versus open approaches, and strategies for reconstruction. Surgery is both affected by, and affects, the physiology of these infants and is an important factor in determining long-term outcomes. Here we discuss the evidence and provide insight surrounding this complex decision making, technical pearls, and outcomes in repair of CDH.

Update on Management and Outcomes of Congenital Diaphragmatic Hernia

Infants with congenital diaphragmatic hernia (CDH) benefit from comprehensive multidisciplinary teams that have experience in caring for the unique and complex issues associated with CDH. Despite prenatal referral to specialized high-volume centers, advanced ventilation strategies and pulmonary hypertension management, and extracorporeal membrane oxygenation, mortality and morbidity remain high. These infants have unique and complex issues that begin in fetal and infant life, but persist through adulthood. Here we will review the literature and share our clinical care pathway for neonatal care and follow up. While many advances have occurred in the past few decades, our work is just beginning to continue to improve the mortality, but also importantly the morbidity of CDH.

Congenital diaphragmatic hernia repair analysis in relation to postoperative abdominal compartment syndrome and delayed abdominal closure

AIM

Limited abdominal space in congenital diaphragmatic hernia (CDH) might result in abdominal compartment syndrome (ACS) and require delayed abdominal closure (DAC). This study reviewed outcomes in pediatric ACS/DAC after CDH repair.

METHODS

Medline/PubMed, Scopus, Web of Science, Ovid and Lilacs databases were reviewed. Data from studies published in English/Spanish/Portuguese between 1990-2020 was collected. Results are presented as descriptive statistics.

RESULTS

Sixteen reports offered 118 children, 112 (94.9%) being neonates. There were six ACS (5.1%) and 112 DAC (94.9%). Regarding ACS, the diagnosis was made clinically (n = 4; 66.7%), using Doppler scans (n = 1; 16.7%) or bladder pressure measurement (n = 1; 16.7%). There was one (16.7%) lethal outcome. The rationale to perform DAC was not clearly stated, and measurement of abdominal pressure was not mentioned in all reports. Silo was the preferred approach in 36 children (32.1%), followed by skin closure only (n = 16; 14.3%), vacuum (n = 10; 8.9%), fascia patch and skin closure (n = 5; 4.5%), fascia patch and vacuum dressing (n = 1; 0.9%), fasciotomy (n = 1; 0.9%); with no DAC technique reported in 43 patients (38.4%). Complications after DAC were reported in nine children (8.1%). One DAC using vacuum dressing that was clinically diagnosed with ACS required silo placement. There were 19 (17%) lethal outcomes.

CONCLUSIONS

ACS/DAC after CDH repair are reported more frequently in neonates (112/118; 94.9%). There is no clear rationale stated behind the decision to perform DAC, with the silo being the preferred approach. Criteria need to be worked for DAC in CDH with large herniated content and small volume abdomen to prevent ACS.

What Exactly is Meant by "Loss of Domain" for Ventral Hernia? Systematic Review of Definitions

Large ventral hernias are a significant surgical challenge. "Loss of domain" (LOD) expresses the relationship between hernia and abdominal volume, and is used to predict operative difficulty and success. This systematic review assessed whether different definitions of LOD are used in the literature. The PubMed database was searched for articles reporting large hernia repairs that explicitly described LOD. Two reviewers screened citations and extracted data from selected articles, focusing on the definitions used for LOD, study demographics, study design, and reporting surgical specialty. One hundred and seven articles were identified, 93 full-texts examined, and 77 were included in the systematic review. Sixty-seven articles were from the primary literature, and 10 articles were from the secondary literature. Twenty-eight articles (36%) gave a written definition for loss of domain. These varied and divided into six broad groupings; four described the loss of the right of domain, six described abdominal strap muscle contraction, five described the "second abdomen", five describing large irreducible hernias. Six gave miscellaneous definitions. Two articles gave multiple definitions. Twenty articles (26%) gave volumetric definitions; eight used the Tanaka method [hernia sac volume (HSV)/abdominal cavity volume] and five used the Sabbagh method [(HSV)/total peritoneal volume]. The definitions used for loss of domain were not dependent on the reporting specialty. Our systematic review revealed that multiple definitions of loss of domain are being used. These vary and are not interchangeable. Expert consensus on this matter is necessary to standardise this important concept for hernia surgeons.

Disorders of the Diaphragm

Pathologic processes that involve the central nervous system, phrenic nerve, neuromuscular junction, and skeletal muscle can impair diaphragm function. When these processes are of sufficient severity to cause diaphragm dysfunction, respiratory failure may be a consequence. This article reviews basic diaphragm anatomy and physiology and then discusses diagnostic and therapeutic approaches to disorders that result in unilateral or bilateral diaphragm dysfunction. This discussion provides a context in which disorders of the diaphragm and their implications on respiratory function can be better appreciated.

Delayed abdominal closure after congenital diaphragmatic hernia repair

PURPOSE

We present our experience with CDH patients who required delayed abdominal closure following CDH repair.

METHODS

A retrospective review of all CDH repairs from 2004 to 2014 was performed.

RESULTS

233 patients underwent CDH repair, of which 21 required delayed abdominal closure defined as the inability to close the abdominal fascia at the time of CDH repair. The incidence of delayed closure was higher in those undergoing CDH repair on ECMO vs. not on ECMO (40% [17/43] vs. 2% [4/190]; P<0.001). The abdominal wound was temporarily covered by skin only (n=2), skin+prosthetic mesh sutured to the fascia (n=3), preformed silo (n=9), or vacuum assisted closure (VAC®) device (n=7). The mean time to fascial closure was 14.5±7 and 6±3days for patients repaired on ECMO and not on ECMO, respectively. In patients repaired on ECMO, the "primary closure" and "delayed closure" groups were not different in prenatal predictors (liver up, lung-to-head ratio [LHR]), total days on ECMO, ECMO days prior to CDH repair, and survival. In patients repaired on ECMO, the "delayed closure" group had a significantly higher requirement for blood transfusions compared to the "primary closure" group (mean 87±35 vs. 62±27ml of packed RBCs per ECMO day; P=0.01).

CONCLUSION

Delayed abdominal closure was required in 40% of CDH repairs done on ECMO but was rarely required in CDH repairs performed off ECMO. Although associated with an increased need for blood transfusions, delayed closure following CDH repair on ECMO was not associated with increased mortality.

Capillary-like network formation by human amniotic fluid-derived stem cells within fibrin/poly(ethylene glycol) hydrogels

A major limitation in tissue engineering strategies for congenital birth defects is the inability to provide a significant source of oxygen, nutrient, and waste transport in an avascular scaffold. Successful vascularization requires a reliable method to generate vascular cells and a scaffold capable of supporting vessel formation. The broad potential for differentiation, high proliferation rates, and autologous availability for neonatal surgeries make amniotic fluid-derived stem cells (AFSC) well suited for regenerative medicine strategies. AFSC-derived endothelial cells (AFSC-EC) express key proteins and functional phenotypes associated with endothelial cells. Fibrin-based hydrogels were shown to stimulate AFSC-derived network formation in vitro but were limited by rapid degradation. Incorporation of poly(ethylene glycol) (PEG) provided mechanical stability (65%±9% weight retention vs. 0% for fibrin-only at day 14) while retaining key benefits of fibrin-based scaffolds-quick formation (10±3 s), biocompatibility (88%±5% viability), and vasculogenic stimulation. To determine the feasibility of AFSC-derived microvasculature, we compared AFSC-EC as a vascular cell source and AFSC as a perivascular cell source to established sources of these cell types-human umbilical vein endothelial cells (HUVEC) and mesenchymal stem cells (MSC), respectively. Cocultures were seeded at a 4:1 endothelial-to-perivascular cell ratio, and gels were incubated at 37°C for 2 weeks. Mechanical testing was performed using a stress-controlled rheometer (G'=95±10 Pa), and cell-seeded hydrogels were assessed based on morphology. Network formation was analyzed based on key parameters such as vessel thickness, length, and area, as well as the degree of branching. There was no statistical difference between individual cultures of AFSC-EC and HUVEC in regard to these parameters, suggesting the vasculogenic potential of AFSC-EC; however, the development of robust vessels required the presence of both an endothelial and a perivascular cell source and was seen in AFSC cocultures (70%±20% vessel length, 90%±10% vessel area, and 105%±10% vessel thickness compared to HUVEC/MSC). At a fixed seeding density, the coculture of AFSC with AFSC-EC resulted in a synergistic effect on network parameters similar to MSC (150% vessel length, 147% vessel area, 150% vessel thickness, and 155% branching). These results suggest that AFSC-EC and AFSC have significant vasculogenic and perivasculogenic potential, respectively, and are suited for in vivo evaluation.

Abdominal wall closure in neonates after congenital diaphragmatic hernia repair

PURPOSE

Repair of Congenital Diaphragmatic Hernia (CDH) abruptly increases intra-abdominal pressure. This study sought to characterize the incidence and significance of ACS and delayed fascial closure (DFC) after CDH repair.

METHODS

We reviewed the CAPSNet database from 2006 to 2011, identifying the subset of patients that developed ACS or required DFC. Prenatal and demographic information, operative and physiologic details, and outcomes were investigated.

RESULTS

Of 349 patients with CDH, 3 (0.8%) were diagnosed with ACS, while 43 patients (12%) had DFC at the time of CDH repair. Patients more often had right-sided defects (26% vs 13%, p=0.04) and trended toward requiring a patch repair (41% vs 31.2%, p=0.23) and having a liver lobe above the diaphragmatic rim (47% vs 32.7, p=0.09). Patients with ACS or DFC had increased length of stay (47.5 vs 33.9, p=0.01), days fasting (8.2 vs 5.8, p=0.01), days on parenteral nutrition (23.6 vs 15.5, p=0.003), and days on mechanical ventilation (16.3 vs 9.0, p=0.001).

CONCLUSIONS

While ACS in neonates after CDH repair is rare (<1%), DFC is required relatively commonly (>10%) and is associated with right-sided diaphragmatic hernias. Inability to close abdominal fascia is associated with increased morbidity. Clinicians caring for neonates with CDH should be facile with strategies to manage delayed abdominal fascia closure.

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.

Neonatal endosurgical congenital diaphragmatic hernia repair: a systematic review and meta-analysis

OBJECTIVE

To compare outcomes of open and endosurgical neonatal congenital diaphragmatic hernia (CDH) repairs.

BACKGROUND

Historically a surgical emergency, neonatal CDH repair is now deferred pending stabilization of characteristically labile cardiopulmonary physiology. Usually accomplished via laparotomy, surgical repair may acutely worsen lung function; conversely, by reducing the visceral hernia, surgery might improve it. Theoretically, endosurgical repair could minimize deleterious effects of surgery while garnering benefits from decompressing the CDH lung. As endosurgical repair gains popularity, it is important to investigate whether or not minimally-invasive neonatal CDH repair has benefits.

METHODS

We searched Medline, Embase, and Cochrane Trials databases for studies comparing open with endosurgical CDH repair. Non-neonatal series and reports without comparison groups were excluded. References from papers and conference proceedings were also hand searched. Meta-analysis used a fixed effects model and was reported in accordance with PRISMA.

RESULTS

We included 3 studies (1 unpublished; none randomized); all compared thoracoscopic and open CDH repair and together described 143 patients. All studies had limitations, including use of historical controls. Demographics, CDH sidedness, APGAR and associated anomaly prevalence were similar between groups. For endosurgical repair, recurrence was higher (RR: 3.2 [1.1, 9.3], P = 0.03) and operative time longer (WMD 50 minutes [32, 69], P < 0.00001). Survival and patch usage were not different between open and endosurgical groups.

CONCLUSIONS

Neonatal thoracoscopic CDH repair has greater recurrence rates and operative times but similar survival and patch usage compared with open surgery. A prospective registry for all such cases would guide development of trials (Stage 2b; IDEAL recommendations).

Salvaging the severe congenital diaphragmatic hernia patient: is a silo the solution?

BACKGROUND

Infants with severe congenital diaphragmatic hernia (CDH) requiring extracorporeal membrane oxygenation (ECMO) have a high morbidity and mortality. We hypothesized that placement of an abdominal wall silo and staged abdominal wall closure may reduce problems associated with decreased abdominal domain in CDH.

METHODS

We performed a retrospective review and identified 7 CDH patients requiring ECMO who had a silastic abdominal wall silo between 2003 and 2006. Variables analyzed included survival, ECMO duration, duration of silo, time to discharge, and long-term outcome.

RESULTS

Predicted mean survival for the entire cohort using the published CDH Study Group equation was 47% (range, 9%-86%). All 7 patients (100%) survived. Extracorporeal membrane oxygenation duration averaged 15 days (range, 5-19 days). Four of the patients (58%) were repaired with a silo on ECMO, and 3 (42%) had their repair after ECMO. The abdominal wall defect was closed at a mean of 21 days (range, 4-41 days). Hospital stay after silo placement averaged 54 days (range, 20-170 days) with no infections or wound complications.

CONCLUSIONS

Abdominal wall silo placement in infants with CDH requiring ECMO appears to be an effective strategy for decreased abdominal domain. Further studies are warranted to determine the efficacy of such a strategy for these high-risk CDH patients.

Surgical management of neonates with congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is one of the most challenging and complex pediatric abnormalities to manage, both medically and surgically. The care of these neonates has seen significant evolution, from previous aggressive ventilation and emergent operation to current permissive hypercapnea, physiologic stabilization, and elective surgical repair, all in less than two decades. These changes have led to many centers reporting survival rates near 80%, a dramatic improvement from the 50% survival reported in the 1970s. This review covers the current principles guiding the surgical management of CDH in the neonate, including preoperative stabilization, operative timing, extracorporeal membrane oxygenation, surgical approach, and management of recurrence. Although many clinical challenges remain, multi-institutional collaboration and ongoing research efforts will hopefully improve the clinical care of these patients.

Implantation of a cone-shaped double-fixed patch increases abdominal space and prevents recurrence of large defects in congenital diaphragmatic hernia

BACKGROUND

Large defects in patients with congenital diaphragmatic hernia (CDH) are frequently closed with a polytetrafluoroethylene patch (PTFE). Intraoperative problems include lack of abdominal domain for the reduction of organs and closure of the abdominal wall. Main surgical postoperative complication is the recurrence of the hernia. We suggest a new and easy method of patch implantation, improving these problems, and report first follow-up results.

METHODS

In our clinic, 103 children with CDH were treated, and 87 children underwent reconstruction of the diaphragm in the 5 years between 1998 and 2002. In 52 patients, a patch implantation had to be performed. We have been optimizing our complete pediatric and surgical procedure and present a new standardized technique of preparation and implantation of a PTFE patch. The flat patch is folded to a 90 degrees cone. The cone is fixed in its form with few single stitches. It is implanted with an overlapping border of 1 cm circumferentially. The border is separately fixed with absorbable single stitches to keep from rolling up. The rough side of the patch points toward the rim of the diaphragm to enable ingrowth of the connective tissue. In a 1-year follow-up study, the recurrences in the 3 following groups of PTFE patches were studied: conventional implantation (simple patch without overlapping border), patch with separately fixed overlapping border, and cone-shaped patch with overlapping separately fixed border.

RESULTS

Thirty-three patients were included in the study. After conventional PTFE-patch implantation, 6 (46%) of 13 patients developed reherniation. After PTFE-patch implantation with separately fixed overlapping border, 1 (11%) of 9 patients had a recurrent hernia. In the group with the PTFE-cone implantation, 1 (9%) of 11 patients developed a recurrence. Meanwhile, another 20 CDH patients received implantation of a cone-shaped patch, and no further recurrence occurred up to now. With the additional space (20 mL) provided by the cone-shaped patch, the closure of the abdomen was easier, and the fundus had intraoperatively a physiological position.

CONCLUSION

This optimized patch implantation technique in large diaphragmatic defects offers considerable advantages especially regarding recurrence of the hernia and closure of the abdomen, which are currently the most challenging surgical problems. 1. The cone-shaped 3-dimensional patch increases abdominal capacity. 2. Redundant chest capacity is reduced, and the reconstructed diaphragm shows a physiological shape. 3. The dome of the patch allows a physiological position of the gastric fundus and a normal Hiss angle, thus preventing gastroesophageal reflux. 4. Additional safety of the implantation is achieved by separate fixation of the overlapping border of the cone, preventing recurrence.

The amniotic fluid as a source of cells for fetal tissue engineering

PURPOSE

This study was aimed at determining whether fetal tissue constructs can be engineered from cells normally found in the amniotic fluid.

METHODS

A subpopulation of morphologically distinct cells was isolated mechanically from the amniotic fluid of pregnant ewes (n = 5) and expanded selectively. Its lineage was determined by immunofluorescent staining against multiple intermediate filaments and surface antigens. Proliferation rates were determined by both oxidation and total DNA assays and compared with immunocytochemically identical adult and fetal sheep cells. Statistical analysis was by analysis of variance for repeated measures (ANOVA). After expansion, the amniocytes were seeded onto a polyglycolic acid polymer/poly-4-hydroxybutyrate scaffold. The resulting construct was analyzed by both optical and scanning electron microscopy.

RESULTS

The immunocytochemical profile of expanded amniocytes was consistent with a mesenchymal, fibroblast/myofibroblast cell lineage. These cells proliferated significantly faster than comparable fetal and adult cells in culture. Amniocyte construct analysis showed dense, confluent layers of cells firmly attached to the scaffold, with no evidence of cell death.

CONCLUSIONS

(1) Subpopulations of fetal mesenchymal cells can be isolated consistently from the amniotic fluid. (2) Mesenchymal amniocytes proliferate more rapidly in vitro than comparable fetal and adult cells. (3) Mesenchymal amniocytes attach firmly to polyglycolic acid polymer. The amniotic fluid can be a reliable and practical source of cells for the engineering of select fetal tissue constructs.

Surgical embryology and anatomy of the diaphragm with surgical applications

This article reviews the development, surgical anatomy, and teratology of the diaphragm, and discusses the diagnostic procedures, surgical therapy, and prognosis of congenital disturbances. Special attention is paid to the traumatic rupture of the diaphragm, concerning incidence, cause, diagnosis, prognosis, and surgical repair.

Current surgical management of congenital diaphragmatic hernia: a report from the Congenital Diaphragmatic Hernia Study Group

BACKGROUND

Repair of congenital diaphragmatic hernia (CDH) has changed from an emergent procedure to a delayed procedure in the last decade. Many other aspects of management have also evolved since the first successful repair. However, most reports are from single institutions. The lack of a large multicenter database has hampered progress in the management of congenital diaphragmatic hernia (CDH) and makes determination of the current standard difficult.

METHODS

The CDH study group was formed in 1995 to collect data from multiple institutions in North America, Europe, and Australia. Participating centers completed a registry form on all live-born infants with CDH during 1995 and 1996. Demographic information, data about surgical management, and outcome were collected for all patients.

RESULTS

Sixty-two centers participated, with 461 patients entered. Overall survival was 280 of 442 patients (63%) where survival was recorded. The defect was left-sided in 78%, right-sided in 21%, and bilateral in 1%. A subcostal approach was used in 91% of patients, with pleural drainage used in 76%. A patch of some kind was used in just over half (51%) of the patients, with polytetrafluoroethylene being the most commonly used material (81%) in those patients with a patch. The mean surgical time was 102 minutes, with an average blood loss of 14 mL (range, 0 to 500 mL). The overwhelming majority of patients underwent repair between 6:00 AM and 6:00 PM (289 of 329, 88%). Nineteen percent of patients had surgical repair on extracorporeal membrane oxygenation (ECMO) at a mean time of 170 hours into the ECMO course (range, 10 to 593 hours). The mean age at surgery in patients not treated with ECMO was 73 hours (range, 1 to 445 hours).

CONCLUSIONS

The multicenter nature of this report makes it a snapshot of current management. The data would indicate that prosthetic patching of the defect has become common, that after-hours repair is infrequent, and that delayed surgical repair has become the preferred approach in many centers. Furthermore, the mean survival rate of 63% indicates that despite decades of individual effort, the CDH problem is far from solved. This highlights the need for a centralized database and cooperative multicenter studies in the future.

[Thoracic reconstruction with polytetrafluoroethylene prosthesis]

Thoracic wall resections are performed to treat a wide variety of conditions. Reconstruction techniques have varied considerably since the introduction of synthetic prosthesis, the most recent of which are made of polytetrafluoroethylene (PTFE, or Gore-Tex). We describe our department's experience with PTFE prosthesis. PTFE was used in 21 patients treated for various diseases. Thirteen reconstructions were of the thoracic wall, 4 were of the diaphragm and 4 of the pericardium. Three of the 13 thoracic wall reconstructions involved bilateral myoplasty of the pectoralis major, 2 involved omentoplasty and 1 required use of a wide musculocutaneous flap. Complications included pneumonia in 2 cases and 1 seroma with chronic cutaneous fistula that required removal of the prosthesis after 9 months. Two patients died, 1 after 19 days and the other after 9 months, both as a result of causes unrelated to reconstruction. Follow-up of these patients ranged from 3 to 54 months. We recommend the prosthetic use of PTFE for thoracic wall reconstruction, along with plasty or musculocutaneous flaps when necessary.

Prenatal diagnosis of congenital diaphragmatic hernia and pulmonary hypoplasia and therapeutic strategy

The outcome of fetuses with congenital diaphragmatic hernia (CDH) has been reported to be fatal when pulmonary hypoplasia (PH) is severe. As an indicator of PH, we attempted to measure the lung-thorax transverse area ratio (L/T) using ultrasonic echography. Immediate postnatal surgery was performed using high-frequency oscillatory ventilation (HFOV) and sometimes followed by extracorporeal membrane oxygenation (ECMO). Eighteen fetuses were treated and 14 survived. L/T correlated well with the best preductal arterial blood gas data before surgical reduction during manual ventilation and HFOV, while preductal PO2 and alveolar-arterial oxygen differences from patients managed with HFOV were better than those in patients with manual ventilation. Although L/T also correlated with the duration of O2 therapy and hospitalization in survivors without major anomalies, there was no significant difference between L/T in survivors and nonsurvivors. Because delayed institution of ECMO and complications related to ECMO management seemed to be a major cause of death in non-survivors, the unsalvageable L/T due to PH was estimated to be below 0.06 for HFOV and below 0.1 for conventional ventilation based on the correlation between L/T and preductal P02. These results suggest that L/T is a useful indicator of PH in patients with CDH and also that HFOV is advantageous in treating CDH with PH. The advantage of prenatal diagnosis in predicting unsalvageable L/Ts, should be considered in the therapeutic strategy.

Prenatal glucocorticoid therapy reverses pulmonary immaturity in congenital diaphragmatic hernia in fetal sheep

OBJECTIVE

To assess the feasibility of conducting clinical trials of prenatal steroid therapy for congenital diaphragmatic hernia (CDH) in humans, the authors tested whether prenatal glucocorticoid, currently the standard treatment to minimize respiratory distress syndrome in premature infants, might improve the pulmonary immaturity in severe CDH in a large animal model.

SUMMARY BACKGROUND DATA

The authors have used the nitrofen-induced rat model of CDH, which demonstrates immature lungs by biochemical, morphometric, and molecular biologic criteria. They also have shown that the lethally immature lungs of the full-term CDH rats can be improved by biochemical, morphometric, physiologic, and molecular criteria by treating the mothers with parenteral steroids at doses extrapolated from the current therapy used to accelerate lung development of premature human babies.

METHODS

During a 3-year period in 88 fetal sheep, 1) left-sided diaphragmatic hernias were created surgically at varying gestational ages (day 78-90; term = 142-145 days) and size to maximize severity (n = 45), 2) placement and design of indwelling fetal intravenous catheters were optimized (n = 13), and 3) timing and dosage of cortisol administration were determined (n = 17). As a result, diaphragmatic hernias were created on day 80, intravenous catheters were placed on day 120, and twice-daily intravenous cortisol injections (n = 8) or saline as the control (n = 5) were administered (days 133-135). Lambs were delivered on day 136 via cesarean section to avoid steroid-induced abortion; vascular access was obtained, and the fetuses were ventilated at standard settings. Physiologic data were collected, and lungs were harvested for biochemical and histologic analysis.

RESULTS

Significant improvements were measured in postductal arterial oxygen pressure ([PaO2] 38 +/- 6 mmHg after cortisol therapy compared with 20 +/- 3 mmHg for saline controls; p = 0.002) and in dynamic compliance (0.42 +/- 0.05 mL/cm H2O vs. 0.29 +/- 0.01 mL/cm H2O; p = 0.01). Lung glycogen levels in the right lung of the cortisol group were significantly better than controls (4.6 +/- 0.3 mg/g lung vs. 6.8 +/- 0.4 mg/g; p = 0.002), as were protein/DNA levels (8.3 +/- 0.9 mg/mg vs. 14.5 +/- mg/mg; p < 0.05). Striking morphologic maturation of airway architecture was observed in the treated lungs.

CONCLUSIONS

Prenatal glucocorticoids correct the pulmonary immaturity of fetal sheep with CDH by physiologic, biochemical, and histologic criteria. These data, combined with previous small animal studies, have prompted the authors to initiate a prospective phase I/II clinical trial to examine the efficacy of prenatal glucocorticoids to improve the maturation of hypoplastic lungs associated with CDH.