EXIT-to-airway: Fundamentals, prenatal work-up, and technical aspects

Ex-utero intrapartum treatment (EXIT) is a delivery strategy developed to manage a variety of prenatally diagnosed conditions in the transition to newborn life. This procedure allows control and provides time for intervention in otherwise life-threatening malformations, such as congenital upper airway obstructions. EXIT-to-airway has changed the outcome of fetuses with these anomalies. The main purpose of this intervention is to improve the safety of establishing a reliable airway at birth. Maximal but controlled uterine relaxation to maintain feto-maternal perfusion and thus gas exchange, while keeping the fetal and maternal well-being are the paradigms of any type of EXIT. The most important aspect of fetal airway management is to consolidate a highly trained, well-coordinated, multidisciplinary team that is prepared for every contingency. A comprehensive prenatal assessment, including ultrasound, fetal echocardiogram, fetal MRI, and genetic testing is imperative for patient selection. Extensive preoperative planning, ad-hoc team meetings, and surgical simulations for challenging cases are critical strategies to achieve the best outcomes. This article outlines the prenatal work-up, decision making, technical aspects, and principles for a successful EXIT-to-airway procedure.

CHAOS: A fetal autopsy report

Congenital high airway obstruction syndrome (CHAOS) is a rare congenital malformation, which results from deficient recanalization of the upper airways. Laryngeal atresia is the most common cause, other etiologies being trachea atresia, laryngeal or tracheal webs, subglottic stenosis, obstructing laryngeal cysts, and laryngeal or tracheal agenesis. There is decreased clearance of the fluid produced by fetal lungs due to obstruction leading to increased intratracheal pressure and thereby secondary proliferative lung growth. The heart becomes compressed in the midline due to hyperexpansion of the lungs causing elevated intrathoracic pressure, decreased venous return, and fetal cardiac failure. This sequence causes ascites, placento-megaly, and eventually hydrops fetalis. We present a case of antenatal diagnosis of a fetus with CHAOS corroborated by fetal autopsy.

Prenatal diagnosis of laryngo-tracheo-esophageal anomalies in fetuses with congenital diaphragmatic hernia by ultrasound evaluation of the vocal cords and fetal laryngoesophagoscopy

BACKGROUND

To evaluate the incidence of laryngeal ultrasound (US) abnormalities in fetuses with congenital diaphragmatic hernia (CDH) and to assess the utility of fetal laryngoesophagoscopy for prenatal diagnosis of laryngo-tracheo-esophageal anomalies.

STUDY DESIGN

A cohort of CDH fetuses with laryngeal ultrasound abnormalities were selected for diagnostic fetal laringoesophagoscopy in a single fetal surgery center at Queretaro, Mexico.

RESULTS

During the study period, 210 CDH fetuses were evaluated. US examination of the vocal cords was successfully performed in all fetuses, and abnormal ultrasound findings were observed in four cases (1.9%). Fetal laringoesophagoscopy was successfully performed in all four cases at a median gestational age of 29.5 (range, 28.1-30.6) weeks. During fetal intervention, a laryngo-tracheo-esophageal cleft (TEC) extending from the larynx to the carina (type IV) was endoscopically visualized in three cases, and laryngeal atresia coexisting with TEC was confirmed in the remaining case. Fetal karyotype was normal in all cases, but abnormal chromosomal microarray analysis was reported in two cases (50%). All cases were delivered liveborn with severe respiratory failure presenting cardiac arrest and immediate neonatal death.

CONCLUSIONS

Laryngeal anomalies in CDH fetuses can be presumed by ultrasound evaluation of the vocal cords and confirmed by fetal laryngoesophagoscopy during pregnancy.

Congenital High Airway Obstruction Syndrome (CHAOS): No Intervention, No Survival-A Case Report and Literature Review

Congenital high airway obstruction syndrome (CHAOS) is complete or partial obstruction of the fetal upper airway. CHAOS is a rare and fatal condition if no perinatal intervention is done. Antenatal sonographic imaging has typical findings that can help in an early diagnosis, which is important in deciding elective termination of the pregnancy or successful planning of appropriate perinatal management.

Prenatal sonographic appearance of laryngeal atresia: A case report

Detailed assessment of the larynx is not easy because of its complex structures and the associated technical difficulties. We performed sonography in multiple planes to assess the laryngeal anatomy and movements of a fetus with laryngeal atresia. The distended trachea ended abruptly with an echogenic non-structured larynx which showed shallow rapid "flutter-like" movements and up and down but not adduction- abduction movements during swallowing. Shadowing from the chin could be reduced by scanning through fluid in the oral cavity or between the transverse processes of vertebrae in a coronal plane.

A Technical Look at Fetoscopic Laser Ablation for Fetal Laryngeal Surgical Recanalization in Congenital High Airway Obstruction Syndrome

Background: Congenital high airway obstruction syndrome (CHAOS) is a rare condition characterized by complete obstruction of the upper fetal airways. Left untreated, it is uniformly fatal. Ex utero intrapartum treatment (EXIT) has been used to establish a surgical airway in affected fetuses during delivery. While this procedure benefits those fetuses that survive to delivery, high mortality in the prenatal period necessitates earlier innovative strategies. Herein, we report a novel technique for in utero intervention. Methods: A fetoscopic intervention was performed at 28 weeks on a 35-year-old G1P0 woman with fetal CHAOS from a laryngeal obstruction measuring 11 mm in length on prenatal imaging. Under ultrasound guidance, a 3.3-mm curved fetoscope was used to access the uterine cavity through a single subcentimeter maternal skin incision. The scope was driven through the fetal oral cavity and manipulated to attain a view of the vocal cords. A subglottic obstruction was observed. A 600-micron laser fiber was passed through the working channel of the scope and used to ablate the obstructed airway. Using the laser fiber and a guidewire, the ablated opening was traversed with the fetoscope to the level of the carina. Results: Postoperatively, the lungs became less hyperinflated. There was improvement in ascites and diaphragmatic eversion. At 31 1/7 weeks' gestation, the mother experienced preterm premature rupture of membranes with active labor and the fetus was delivered through EXIT to tracheostomy. The infant was managed on mechanical ventilation and is currently thriving at home with a tracheostomy at 2 years of age. Conclusion: Fetoscopy with laser ablation of the airway obstruction is an effective prenatal management strategy that offers the potential to alter the devastating natural course of CHAOS.

Injection bronchoplasty with carboxymethlycellulose with cystoscopy needle for neonatal persistent bronchopleural fistulae

OBJECTIVE

We describe the novel use of injectable carboxymethylcellulose to close a persistent bronchopleural fistula (BPF) in a neonate who underwent an ex utero intrapartum treatment (EXIT) after aborted fetoscopy.

METHODS

In this case, a patient with laryngeal atresia underwent fetoscopy that was halted after concern for instruments within the mediastinum, and thus ultimately required an EXIT to establish an airway. Bilateral pneumothoraces and eventually multiple BPF were identified that continued to persist despite multiple attempts at removal of chest tubes over a four-week period. We look at the role of endoscopy and a substance often used in the larynx to help close a persistent BPF.

RESULTS

At initial bronchoscopy, no BPF was identified, but at subsequent evaluation due to persistent pneumothorax, we used increased positive end expiratory pressure to help reveal the fistula. Given the bronchial location of the fistula, traditional laryngeal instruments could not be used, requiring the use of urologic cystoscopy needles to assist in accessing these challenging locations. At postoperative day 2 from the injection, the chest tube was removed and did not require replacement.

CONCLUSION

There are many methods to help treat BPF. The endoscopic injection of carboxymethylcellulose adds a technique to the pediatric otolaryngologist's armamentarium.

Causes of death shortly after delivery and medical malpractice claims in congenital high airway obstruction syndrome: Review of the literature

Congenital High Airway Obstruction Syndrome is a rare pathology that may conduct the baby to death shortly after delivery. This outcome may cause emotional distress in the parents but it may also generate expensive medical malpractice claims about the reasons why the syndrome was not identified and/or correctly treated. The authors conducted a review of the cases in which Congenital High Airway Obstruction Syndrome caused death of the baby shortly after delivery. Then, they pointed out these ultrasonographic and anatomical reasons why the syndrome may be not identified and/or correctly treated: negative prenatal ultrasonography, recurrence of non-specific findings at prenatal ultrasonography, connection of respiratory and gastrointestinal tracts, tracheal agenesis or atresia, parent's refuse of post-partum therapeutic procedures, multiple malformations of the fetus/child. In conclusion, the authors highlighted that death shortly after delivery is usually caused by specific conditions that are not influenced by healthcare team's practice.

Fetoscopy-Assisted Percutaneous Decompression of the Distal Trachea and Lungs Reverses Hydrops Fetalis and Fetal Distress in a Fetus with Laryngeal Atresia

We present a case of prenatal hydrops secondary to congenital high airway obstruction syndrome (CHAOS) that was treated with fetoscopy-assisted needle decompression. A 22-year-old G3P2 woman presented after a 21-week ultrasound demonstrated CHAOS. The fetus developed hydrops at 25 weeks, characterized by abdominal ascites, pericardial effusion, and scalp edema. Fetal MRI showed complete obstruction of the glottis and subglottic airway, suggestive of laryngeal atresia. At 27 weeks, due to the progression of the hydrops, operative fetoscopy was proposed and performed. Fetal laryngoscopy confirmed fusion of the vocal cords and laryngeal atresia. The atretic segment was a solid cartilaginous block, preventing intubation. Using the fetoscope to stabilize the fetal head and neck, we performed ultrasound-guided percutaneous needle drainage of the cervical trachea through the anterior fetal neck. We removed 17 mL of viscous fluid from the lower trachea, resulting in immediate lung decompression. Two weeks later, ultrasound confirmed hydrops resolution. The patient was delivered and tracheostomy performed at 30 weeks via an ex utero intrapartum treatment (EXIT) procedure after progression of preterm labor. At 27 days of life, the infant was stable on minimal ventilator support. To our knowledge, this is the first successful report of an ultrasound-guided percutaneous tracheal decompression through the anterior neck of a fetus with CHAOS secondary to laryngeal atresia.

Congenital high airway obstruction syndrome (CHAOS): Natural history, prenatal management strategies, and outcomes at a single comprehensive fetal center

PURPOSE

Congenital high airway obstruction syndrome (CHAOS) is a devastating fetal condition of complete airway discontinuity resulting in significant hydrops and extreme lung hyperplasia. It is universally fatal with survival reported only in the rare spontaneous fistulization or EXIT intervention (Ex Utero Intrapartum Treatment). Even in these cases, mortality remains high, and current investigations are targeting prenatal interventions. This report describes our experience with management and fetal interventions for CHAOS, including laser laryngotomy.

METHODS

We retrospectively reviewed all patients diagnosed with CHAOS at a single academic institution between 2006 and 2017.

RESULTS

Fifteen patients were identified. Eight had obstruction at the trachea and seven at the larynx. In the laryngeal obstructions, three expired shortly after birth, and one survived after spontaneous fistulization and subsequent EXIT to tracheostomy. The remaining three underwent in-utero treatment with laser laryngotomy. One had preterm premature rupture of membranes (PPROM), delivered 3 days post-operatively, and died. Two underwent EXIT to tracheostomy with one surviving to discharge and is currently 2 years old.

CONCLUSION

Our study demonstrates the outcomes of a large series of patients diagnosed with CHAOS. While mortality remains high, options for fetal intervention are being explored to allow alterations in the prenatal natural history and improve postnatal outcomes.

TYPE OF STUDY

Retrospective Treatment Study.

LEVEL OF EVIDENCE

Level IV.

Antenatal Ultrasound Diagnosis of Congenital High Airway Obstruction Syndrome: A Case Report and Review of Literature

Congenital high airway obstruction syndrome (CHAOS) is a rare life-threatening fetal condition resulting from obstruction of the upper fetal airway which may be partial or complete. Prenatal diagnosis is crucial as it usually results in stillbirth or death after delivery if unrecognized. We report a case of CHAOS that was diagnosed prenatally due to characteristic ultrasound features. We also briefly review literature in light of current management options.

Management of CHAOS by intact cord resuscitation: case report and literature review

Background: Congenital high airway obstruction syndrome (CHAOS) is a near fatal condition, except when the ex utero intrapartum treatment (EXIT) procedure is performed as rescue. After antenatal diagnosis of the condition, counseling regarding prognosis and outcome needs to be provided.Case: We describe here a case with CHAOS due to isolated fetal laryngeal atresia, presented at our center at 33-week gestation. After counseling regarding the uncertain outcome, consent for elective caesarean was not given. Intact cord resuscitation (ICR) was done as a rescue by a well-coordinated team during delivery. Tracheostomy was performed successfully under local anesthesia within five minutes, while the cord was still attached to the placenta. The baby had supraglottic stenosis on CT scan. Reconstructive surgery is planned after 8 months. The literature review showed 24 reports of 28 cases with intrinsic airway obstruction managed by EXIT, laryngeal atresia was the most common cause (18/28). The outcome was poor in tracheal agenesis (1/4 survived) whereas those having laryngeal web or small communication (4/4 survived) had better outcome. Tracheal reconstruction was done in 3/28 cases only.Conclusions: The case emphasizes that ICR and tracheostomy during vaginal delivery can rescue the baby. The literature reviewed provided insight into the outcome of CHAOS cases in world literature.

Creating Order Out of Chaos - Role of Antenatal Ultrasound in Diagnosis

Background

Congenital high airway obstruction syndrome (CHAOS) is a rare fetal anomaly characterized by obstruction of the higher fetal airway. This could be either complete or incomplete and is more commonly seen at the subglottic level, resulting in a spectrum of characteristic secondary features.

Case Report

In this case study, we report two cases of CHAOS with one showing laryngeal atresia and the other, tracheal atresia. Both these cases showed characteristic findings on a detailed, meticulous USG examination which led to this diagnosis.

Conclusions

Early and accurate diagnosis offers a window of opportunity for parental counseling and management using procedures such as EXIT (ex-utero intrapartum procedure). Earlier, CHAOS was thought to be incompatible with life; however, with the advent of ex-utero intrapartum procedure, a few cases of post-natal survival have been noted in the literature. In this article, we emphasize the sonographic findings found in CHAOS. Early diagnosis offers an opportunity for a intrauterine fetal intervention in potentially lethal cases.

Airway compromise in the fetus and neonate: Prenatal assessment and perinatal management

The fetus with a potentially obstructed airway can be identified on routine antenatal imaging. These cases should be referred to fetal care centers, which have the necessary expertise to fully evaluate and manage these fetuses and neonates appropriately. Complete airway obstruction may result in fetal hydrops and intrauterine demise. If a newborn infant has a compromised airway at delivery, the inability to secure its airway quickly may result in a hypoxic cerebral insult or death. In the most severely affected cases, prenatal, perinatal, or postnatal surgical intervention may be necessary. The timing of such an intervention will depend on the exact cause of the airway obstruction, other associated findings and the anticipated difficulty in establishing an airway at delivery. Fetal ultrasound and magnetic resonance imaging can differentiate between intrinsic and extrinsic airway obstruction, which allows for the optimal planning and management of the delivery and neonatal resuscitation.

CHAOS: Prenatal imaging findings with post mortem contrast radiographic correlation

Congenital high airway obstruction syndrome is a rare fetal anomaly with characteristic constellation of prenatal findings on ultrasound and MRI. The typical triad of imaging features are enlarged and echogenic lungs, flattening or inversion of diaphragm and fetal hydrops. Early prenatal recognition of congenital high airway obstruction syndrome by ultrasound and/or MRI is mandatory for the appropriate perinatal management. We report a case of a male fetus with typical imaging findings of congenital high airway obstruction syndrome on ultrasound and MRI at 19 weeks of gestation. The role of contrast radiographs of fetal airways, including retrograde laryngogram, in confirming the postnatal diagnosis of this fetal condition is demonstrated. The prenatal imaging findings were correlated with contrast radiographs of upper airways, sonography of aborted fetus and fetal autopsy findings.

A Series of Congenital High Airway Obstruction Syndrome - Classic Imaging Findings

Congenital high airway obstruction syndrome (CHAOS) is a very rare entity with very poor prognosis in which upper airway is intrinsically obstructed, the most common reason being laryngeal atresia. In summary prenatal early diagnosis of patients with CHAOS is necessary so that perinatal management can be undertaken successfully or elective termination of pregnancy can be undertaken. The fetoscopic approach may be a life saving modality in a subset of CHAOS patients. Involving a multidisciplinary team comprising of paediatricians, radiologists, obstetricians and anaesthesiologists increases the efficiency of management.

Congenital lung lesions: Prenatal diagnosis and intervention

Congenital lung lesions are common sonographic findings in pregnancy, usually detected at the routine 20 weeks scan. The most common is cystic adenomatous malformation of the lung (CCAM). This usually causes few prenatal problems; however, fetal hydrops occurs in about 5%. Prenatal intervention for these is possible in many to allow survival to birth. Bronchoplumonary sequestration (BPS), with an aberrant "feeder" vessel arising from the aorta may co-exist but is detectable as a separate entity by visualization of this vessel. Symptomatic or curative prenatal intervention is again possible in the few severe cases where hydrops or pleural effusions develop. Pleural effusions may be due to a primary leak usually of chylous fluid: prenatal thoracoamniotic shunting may prevent pulmonary hyoplasia or cure the consequent fetal hydrops. More often, however, effusions are a consequence of an underlying abnormality, including many structural or chromosomal abnormalities that may also cause co-existing fetal hydrops. Congenital high airway obstruction (CHAOS) is commonly fatal but cases potentially amenable to prenatal intervention or to immediate perinatal management may be identified using ultrasound or MRI.

Experimental Evaluation of Tracheo-Amniotic Shunting for Induced Congenital High Airway Obstruction in a Sheep Model

Objective: To evaluate the feasibility of tracheo-amniotic shunting in a sheep model for congenital high airway obstruction syndrome. Material and Methods: High airway obstruction was induced around day 95 (term = 145 days) in 10 lamb fetuses by tracheal clipping. Five days later, ultrasound-guided tracheoamniotic shunting was done using either the Harrison double-pigtail bladder stent (HS) or a double-basket device (BS). Caesarean section (CS) was done around day 110. At each time point, the cardiothoracic index (CTI) was measured. Lung-to-body weight ratio (LBWR) was calculated at fetal necropsy. The primary endpoint was successful shunting defined as anatomically correct placement and functional airway decompression; the secondary endpoint was survival until CS. Results: Two sheep aborted 3 fetuses after tracheal occlusion. Overall, the median CTI at CS was significantly smaller compared to baseline [0.52 (interquartile range, IQR: 0.52-0.54) vs. 0.58 (IQR: 0.54-0.63); p = 0.01]. In the HS group (n = 4), none of the shunts were correctly positioned. In the BS group (n = 3), there was 1 correct shunt placement; however, this fetus was stillborn. Median LBWR suggested pulmonary overgrowth [0.10 (IQR: 0.08-0.11)]. Conclusion: In our hands, using this model with a long and mobile neck and relative oligohydramnios, tracheoamniotic shunting for airway obstruction has a high failure rate. If further pursued, alternative techniques or different models should be considered.

Treatment of a Fetal Tracheal Obstruction by Fetoscopy and Laser

We report below a case of in utero tracheoscopy with laser collapse of a bronchogenic cyst obstructing the fetal trachea. The patient was referred for ultrasonography at 24 weeks of gestation because of fetal hydrops. Tracheoscopy was performed via fetoscopic approach using a single trocar under local anesthesia with lidocaine and ultrasound guidance. This revealed an image suggestive of a cyst obstructing the middle third at the anterior base of the trachea. Coagulation using a diode laser enabled us to collapse this fluid-filled cyst with three 10-watt bursts (3 times 3 s) and to visualize a completely unobstructed tracheobronchial tree with significant pulmonary fluid reflux on removal of the obstacle. The fetal condition improved markedly within 48 h after the procedure. To the best of our knowledge, this is the first described case of in utero treatment of a tracheal obstruction by tracheoscopy and laser. In severe cases of obstruction of the fetal airways, whether the obstacle is situated in a high or low position, fetal endoscopy is of diagnostic and potentially therapeutic utility.

Laser Ablation of Posterior Urethral Valves by Fetal Cystoscopy

Objective: To report the results of fetal cystoscopic laser ablation of posterior urethral valves (PUV) in a consecutive series in two referral centers. Methods: Twenty pregnant women with a presumptive isolated PUV were treated with fetal cystoscopy under local anesthesia. Identification and fulguration of the PUV by one or several firing-contacts with diode laser were attempted. Perinatal and long-term outcomes were prospectively recorded. Results: The median gestational age at procedure was 18.1 weeks (range 15.0-25.6), and median operation time was 24 min (range 15-40). Access to the urethra was achieved in 19/20 (95%) cases, and postoperative, normalization of bladder size and amniotic fluid was observed in 16/20 (80%). Overall, there were 9 (45%) terminations of pregnancy and 11 women (55%) delivered a liveborn baby at a mean gestational age of 37.3 (29.1-40.2) weeks. No infants developed pulmonary hypoplasia and all were alive at 15-110 months. Eight (40% of all fetuses, 72.7% of newborns) had normal renal function and 3 (27.3%) had renal failure awaiting renal transplantation. Conclusion: Fetoscopic laser ablation for PUV can achieve bladder decompression and amniotic fluid normalization with a single procedure in selected cases with anyhydramnios. There is still a significant risk of progression to renal failure pre or postnatally.

Postmortem magnetic resonance appearances of congenital high airway obstruction syndrome

BACKGROUND

Congenital high airway obstruction syndrome (CHAOS) is a rare life-threatening condition characterised by complete or near-complete developmental obstruction of the foetal airway. Although antenatal imaging findings have been described, the postmortem MRI findings have not been reported.

OBJECTIVE

To present postmortem MRI features of CHAOS.

MATERIALS AND METHODS

We retrospectively reviewed our hospital pathology and imaging databases for cases of CHAOS over a 2-year period.

RESULTS

We identified two cases of CHAOS. In both cases, postmortem plain radiographs demonstrated gross abdominal distension with distortion and splaying of the rib cage. Both foetuses had characteristic postmortem MRI findings including large-volume fluid-filled lungs on T2-weighted imaging, diaphragmatic eversion, fluid-filled airway dilatation below the level of obstruction, centrally positioned and compressed heart, and massive ascites. One foetus had an associated limb abnormality.

CONCLUSION

Postmortem MRI in foetuses suspected of having CHAOS allows confirmation of the diagnosis, determination of the anatomical level of the atresia or stenosis, and identification of associated abnormalities without the need for invasive autopsy.

Fetal Endoscopic Tracheal Intubation: A New Fetoscopic Procedure to Ensure Extrauterine Tracheal Permeability in a Case with Congenital Cervical Teratoma

Congenital neck masses are associated with high perinatal mortality and morbidity secondary to airway obstruction due to a mass effect of the tumor with subsequent neonatal asphyxia and/or neonatal death. Currently, the only technique designed to establish a secure neonatal airway is the ex utero intrapartum treatment (EXIT) procedure, which involves neonatal tracheal intubation while fetal oxygenation is maintained by the uteroplacental circulation in a partial fetal delivery under maternal general anesthesia. We present a case with a giant cervical teratoma and huge displacement and compression of the fetal trachea that was treated successfully at 35 weeks of gestation with a novel fetoscopic procedure to ensure extrauterine tracheal permeability by means of a fetal endoscopic tracheal intubation (FETI) before delivery. The procedure consisted of a percutaneous fetal tracheoscopy under maternal epidural anesthesia using an 11-Fr exchange catheter covering the fetoscope that allowed a conduit to introduce a 3.0-mm intrauterine orotracheal cannula under ultrasound guidance. After FETI, a conventional cesarean section was performed uneventfully with no need for an EXIT procedure. This report is the first to illustrate that in cases with large neck tumors involving fetal airways, FETI is feasible and could potentially replace an EXIT procedure by allowing prenatal airway control.