Tracheal agenesis: diagnosis and management

Neonatal Respiratory Distress and Airway Emergency: Report of Two Cases

We discuss two cases of congenital airway malformations seen in our neonatal intensive care unit (NICU). The aim is to report extremely rare events characterized by immediate respiratory distress after delivery and the impossibility to ventilate and intubate the airway. The first case is a male twin born at 34 weeks by emergency caesarean section. Immediately after delivery, the newborn was cyanotic and showed severe respiratory distress. Bag-valve-mask ventilation did not relieve the respiratory distress but allowed for temporary oxygenation during subsequent unsuccessful oral-tracheal intubation (OTI) attempts. Flexible laryngoscopy revealed complete subglottic obstruction. Postmortem analysis revealed a poly-malformative syndrome, unilateral multicystic renal dysplasia with a complete subglottic diaphragm, and a tracheo-esophageal fistula (TEF). The second case is a male patient that was vaginally born at 35 weeks. Antenatally, an ultrasound (US) arose suspicion for a VACTERL association (vertebral defects, anal atresia, TEF with esophageal atresia and radial or renal dysplasia, plus cardiovascular and limb defects) and a TEF, and thus, fetal magnetic resonance (MRI) was scheduled. Spontaneous labor started shortly thereafter, before imaging could be performed. Respiratory distress, cyanosis, and absence of an audible cry was observed immediately at delivery. Attempts at OTI were unsuccessful, whereas bag-valve-mask ventilation and esophageal intubation allowed for sufficient oxygenation. An emergency tracheostomy was attempted, although no trachea could be found on cervical exploration. Postmortem analysis revealed tracheal agenesis (TA), renal dysplasia, anal atresia, and a single umbilical artery. Clinicians need to be aware of congenital airway malformations and subsequent difficulties upon endotracheal intubation and must plan for multidisciplinary management of the airway at delivery, including emergency esophageal intubation and tracheostomy.

Tracheal Agenesis: Vertical Division of the Native Esophagus - A Novel Surgical Approach and Review of the Literature

INTRODUCTION

Tracheal agenesis (TA) is rare and usually fatal. Few survivors with concomitant tracheoesophageal fistulae (TEF) who underwent ligation of the distal esophagus with creation of a spit-fistula and neo-trachea from the proximal esophagus exist. We report a novel surgical technique whereby the esophagus is divided longitudinally to preserve a functional alimentation tract and a parallel neo-trachea. We review the literature of reported cases, including survivors beyond 12 months.

METHODS

Case report and literature review.

RESULTS

A female infant with prenatal polyhydramnios was born at 35 weeks gestation with immediate respiratory distress and absent cry. Oxygenation was maintained with a laryngeal mask airway. Despite a normal appearing larynx, she could not be intubated and emergent neck exploration disclosed no cervical trachea. The patient was placed on extra corporeal membranous oxygenation (ECMO), and later diagnosed with TA, Floyd Type I. Parental desire for reconstruction but refusal of a spit-fistula necessitated a novel procedure. The esophagus was divided longitudinally via a microstapler to preserve the original alimentary tract and create a parallel neo-trachea originating from the TEF and terminating as a cervical stoma. The healing process was complicated but the baby was ultimately discharged to home where she developed normally neurologically until succumbing one night to accidental decannulation at 16 months of age.

CONCLUSION

We describe a novel surgical approach to manage TA. This includes avoiding creation of a spit fistula and preserving the native esophagus. We then survey the literature, reporting the survivorship duration and operative management of 174 reported cases of TA.

EXIT (ex utero intrapartum treatment) in a growth restricted fetus with tracheal atresia

Congenital high airway obstruction syndrome (CHAOS) encompasses a heterogeneous group of pathologies leading to poor lung development and difficulty oxygenating the newborn after delivery. While previously uniformly fatal, the ex utero intrapartum therapy (EXIT) procedure has provided a method to treat these patients and provide an airway to potentiate survival. We present a patient diagnosed prenatally with CHAOS secondary to tracheal atresia complicated by severe intra-uterine growth restriction (IUGR) who was successfully delivered via an EXIT procedure at 33-weeks. Multidisciplinary care and planning is paramount.

Clinical presentation and airway management of tracheal atresia: A systematic review

OBJECTIVES

Tracheal atresia (TA) is a rare congenital condition that typically requires an unexpected and emergent resuscitation in the delivery room. The mortality rate associated is very high, with only a few long-term survival cases reported. We describe the findings of a systematic review on the clinical presentation and airway management of TA.

METHODS

Using the keywords "tracheal atresia", "tracheal agenesis" and "tracheal hypoplasia" a search through Embase and Pubmed databases was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Articles published from 1950 to 2015 in English, French, Italian, Portuguese and Spanish were included. Exclusion criteria were cases of stillborn, and unclear diagnosis or outcome.

RESULTS

149 cases of TA were identified after reviewing 1125 initial references. There was a male preponderance (65%), and associated malformations were described in 94.2% of patients. Prenatal ultrasound was abnormal in 56.3% of cases, with polyhydramnios being the most common finding. The most frequent type of TA was Faro Type C. 94 (41.3%) patients did not survive beyond the first 24 h of life. Only 13 (8.4%) patients survived more than three months of life, after undergoing a variety of surgical approaches.

CONCLUSION

This review, which to our knowledge is the largest one to date, confirms that TA is a rare malformation, occurs more frequently in males, and has a very high mortality rate. Depending on the presence and type of concomitant malformation, as well of the length of the remaining trachea, different surgical management options are described.

Characterization of a biologically derived rabbit tracheal scaffold

There is a clinical need to provide replacement tracheal tissue for the pediatric population affected by congenital defects, as current surgical solutions are not universally applicable. A potential solution is to use tissue engineered scaffold as the framework for regenerating autologous tissue. Rabbit trachea were used and different detergents (Triton x-100 and sodium deoxycholate) and enzymes (DNAse/RNAse) investigated to create a decellularization protocol. Each reagent was initially tested individually and the outcome used to design a combined protocol. At each stage the resultant scaffold was assessed histologically, molecularly for acellularity and matrix preservation. Immunogenicity of the final scaffold was assessed by implantation into a rat model for 4 weeks. Both enzymes and detergents were required to produce a completely acellular (DNA content 42.78 ng/mg) scaffold with preserved collagen and elastin however, GAG content were reduced (8.78 ± 1.35 vs. 5.5 ± 4.8). Following in vivo implantation the scaffold elicited minimal immune response and showed significant cellular infiltration and vasculogenesis. The luminal aspect of the implanted scaffold showed infiltration of host derived cells, which were positive for pan cytokeratin. It is possible to create biologically derived biocompatible scaffolds to address specific pediatric clinical problems. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2126-2135, 2017.

What can regenerative medicine offer for infants with laryngotracheal agenesis?

BACKGROUND

Laryngotracheal agenesis is a rare congenital disorder but has devastating consequences. Recent achievements in regenerative medicine have opened up new vistas in therapeutic strategies for these infants.

OBJECTIVE

To provide a state-of-the-art review concerning recent achievements in tissue engineering as applied to fetal airway reconstruction and to discuss the use of autologous human amniotic stem cells to prepare organs in advance for babies with laryngotracheal agenesis.

DATA SOURCES AND REVIEW METHODS

A structured search of the current literature (up to and including June 2011). The authors searched PubMed, EMBASE, CINAHL, Web of Science, BIOSIS Previews, Cambridge Scientific Abstracts, ICTRP, and additional sources for published and unpublished trials.

RESULTS

Over the past 15 years, progress has been made in advancing the boundaries of regenerative medicine from the laboratory to the clinical setting through translational research. Most experience has been gained with adult stem cells and synthetic materials or decellularized scaffolds. The optimal cell source for fetal tissue engineering remains to be determined, but a combination of decellularized scaffolds and amniotic fluid stem cells holds great promise for fetal tissue engineering.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Current treatment strategies for laryngotracheal agenesis are suboptimal, and fetal tissue engineering offers an alternative to conventional treatments. Use of human amniotic fluid stem cells for preparing autologous tissue-engineered organ constructs prenatally is an attractive concept. Although this approach is still in its experimental stages, further preclinical and clinical studies are encouraged to define its exact role in the pediatric laryngological setting.

A large animal model of the fetal tracheal stenosis/atresia spectrum

BACKGROUND

Treatment of congenital tracheal stenosis/atresia remains essentially unresolved. Previous models of this disease entity have been restricted to rodents and the chick. We sought to establish the principles of a large, surgical animal model of this spectrum of fetal anomalies.

METHODS

Fetal lambs (n = 8) underwent open surgery at 90-112 days gestation. Their cervical tracheas were encircled by a biocompatible polytetrafluoroethylene wrap, so as to extrinsically restrict their external diameter by 25%. Survivors (n = 7) were killed at different time points post-operatively before term. The manipulated tracheal segments were compared with their respective proximal portions (controls). Analyses included morphometry, histology and quantitative extracellular matrix measurements.

RESULTS

At necropsy, the typical gross appearance of tracheal stenosis/atresia was present in all manipulated tracheal segments. Histological findings included the virtual disappearance of the membranous portion of the trachea, along with infolding, fragmentation, and/or posterior fusion of cartilaginous rings, often with disappearance of the airway mucosa. There were significant decreases in diameter (P < 0.001) and total collagen levels (P = 0.005) on the manipulated trachea compared with the control portions. No significant differences were observed in overall elastin or glycosaminoglycan contents. A significant time-dependent increase in elastin was noted on the control, but not the experimental side.

CONCLUSIONS

In a surgical ovine model, controlled extrinsic compression of the fetal trachea leads to morphological and biochemical findings compatible with the congenital tracheal stenosis/atresia spectrum. This simple and easily reproducible prenatal model can be instrumental in the development of emerging therapies for these congenital anomalies.

Fetal tissue engineering

Attempts at harnessing the prospective benefits of the therapeutic use of fetal cells or tissues date many decades before the modern era of transplantation. The first reported transplantation of human fetal tissue took place in 1922. Fetal cells or tissues also have been used as helpful investigational tools since the 1930s. Still, it was only in the last three decades that fetal tissue transplantation in people has started to lead to favorable outcomes, yet by and large anecdotally. This article offers an outlook on a relatively new dimension in fetal cell-based therapies, namely the engineering of tissues in the laboratory, along with its prospective applications.

Tracheal agenesis - a report of two cases

Tracheal agenesis is a rare and in most cases lethal anomaly. It may be suspected because of lack of audible crying, and is often diagnosed right after birth with water soluble contrast medium injected into the oesophagus. We report two cases which were identified at our institution in the last 10 years. Imaging studies and medical records were reviewed in both cases. Patient number one was studied with a single slice computed tomography, patient number two with multislice detector computed tomography (MDCT) with 64 rows. The advantage of MDCT in demonstrating the rare condition of tracheal agenesis and with the same examination showing other coexisting anomalies is discussed.

CONCLUSION

MDCT with 64 rows is an excellent diagnostic tool in diagnosing tracheal agenesis and showing other coexisting anomalies at the same time.

Tracheal agenesis - a report of two cases

Tracheal agenesis is a rare and in most cases lethal anomaly. It may be suspected because of lack of audible crying, and is often diagnosed right after birth with water soluble contrast medium injected into the oesophagus. We report two cases which were identified at our institution in the last 10 years. Imaging studies and medical records were reviewed in both cases. Patient number one was studied with a single slice computed tomography, patient number two with multislice detector computed tomography (MDCT) with 64 rows. The advantage of MDCT in demonstrating the rare condition of tracheal agenesis and with the same examination showing other coexisting anomalies is discussed.

CONCLUSION

MDCT with 64 rows is an excellent diagnostic tool in diagnosing tracheal agenesis and showing other coexisting anomalies at the same time.

Prenatal diagnosis and postnatal management of congenital laryngeal atresia in a preterm infant

Laryngeal atresia is a rare congenital cause of high airway obstruction that can lead to death if not correctly recognized and treated at birth. Postnatal management is difficult and the prognosis is often poor. We report a case of prenatal diagnosis of laryngeal atresia in a fetus that was delivered preterm at 29 weeks of gestation. Tracheotomy was performed as an ex utero intrapartum treatment (EXIT) to guarantee patent airway, and laryngotracheoplasty was performed at 22 months of corrected age. A favorable ventilatory and neurodevelopmental outcome was observed at 33 months of age.

Fetal tracheal reconstruction with cartilaginous grafts engineered from mesenchymal amniocytes

BACKGROUND/PURPOSE

This study was aimed at determining whether cartilaginous grafts engineered from mesenchymal cells normally present in the amniotic fluid could be used in fetal tracheal repair.

METHODS

Ovine mesenchymal amniocytes were expanded in culture, labeled with green fluorescent protein, and seeded onto biodegradable scaffold tubes maintained in chondrogenic medium. After chondrogenic differentiation of the constructs was confirmed, they were used to repair either partial or full circumferential tracheal defects in allogeneic fetal lambs (n = 7). Newborns were evaluated for signs of airway compromise. Implants were harvested over a 10-day period postnatally for multiple analyses.

RESULTS

All 5 lambs that survived to term were able to breathe spontaneously at birth, 4 (80%) of them without stridor. However, variable degrees of stridor developed over time in all but one animal. Mild-to-moderate tracheal stenosis was present in all specimens. Histologically, grafts contained green fluorescent protein-positive cells, were lined with pseudostratified columnar epithelium, and remodeled into a predominantly fibrous cartilage pattern. Implants showed no significant changes in glycosaminoglycans, collagen, and elastin content at harvest.

CONCLUSIONS

Engineered cartilaginous grafts derived from mesenchymal amniocytes may become a viable alternative for tracheal repair. The amniotic fluid can be a practical cell source for engineered tracheal reconstruction.

Agenesis of the trachea: phenotypic expression of a rare cause of fatal neonatal respiratory insufficiency in six patients

Tracheal agenesis is a rare congenital malformation, which is usually fatal in the newborn period. Its incidence is approximately 1 in 50,000 births. Presentation is with respiratory insufficiency and no audible cry. Other anomalies are found in most cases. Six cases of tracheal agenesis were seen in our hospital since 1988. Their medical records were reviewed. Three of our cases classify as Floyd's type III, two as Floyd's type II and one as Floyd's type I. Associated anomalies were found in five cases. The classification of tracheal agenesis, associated anomalies and potential therapeutic options are discussed.

Congenital airway abnormalities in neonates

Airway malformations such as laryngeal atresia, tracheal agenesis and subglottic stenosis are rare and present at birth with significant respiratory distress with or without stridor. There may be an initial improvement on bag and mask ventilation. Repeated attempts at intubation are met with failure. The related embryology and clinical aspect of airway malformations have been discussed. The prognosis in tracheal agenesis is universally fatal but cases with laryngeal atresia and subglottic stenosis may be saved with prompt tracheostomy and later surgical reconstruction.

Fetal tissue engineering: in utero tracheal augmentation in an ovine model

BACKGROUND/PURPOSE

This study was aimed at comparing fetal tissue engineering with autologous free grafting in an ovine model of in utero tracheal repair.

METHODS

Chondrocytes were isolated from both elastic and hyaline cartilage specimens harvested from fetal lambs and expanded in vitro. Cells were seeded dynamically onto biodegradable scaffolds, which then were maintained in a rotating bioreactor for 6 to 8 weeks. Constructs subsequently were implanted into fetal tracheas (n = 15), in a heterologous fashion (group I). In group II, fetuses (n = 5) received autologous free grafts of elastic cartilage harvested from the ear as tracheal implants. In vivo specimens were harvested for histologic analysis at different time-points postimplantation.

RESULTS

In the 12 of 15 surviving fetuses of group I, all constructs were found to resemble normal hyaline cartilage, engraft well despite their heterologous origin, and display time-dependent epithelialization derived from the native trachea. All autologous free grafts were engrafted and epithelialized at birth, retaining histologic characteristics of elastic cartilage, but were more deformed than engineered constructs. Of the lambs allowed to reach term, 5 of 5 in the engineered group and 4 of 5 in the free graft group could breathe spontaneously.

CONCLUSIONS

(1) Tissue-engineered cartilage, as well as autologous free grafts, can be implanted successfully into the fetal trachea, resulting in engraftment and function. (2) Engineered cartilage provides enhanced structural support after implantation into the fetal trachea when compared with free grafts. Prenatal tracheoplasty may prove useful for the treatment of severe congenital tracheal malformations.