More or less CHAOS: case report and literature review suggesting the existence of a distinct subtype of congenital high airway obstruction syndrome

Abstract

Congenital obstruction of the upper airway (CHAOS) is CASE REPORTA 27-year-old woman, gravida 2, para 1, was referred to our institution at 31 weeks of gestation. Previous ultrasound findings at 17, 20 and 23 weeks were interpreted as suggestive of bilateral congenital cystic adenomatoid malformation (CAM) of the lung, Type III. Both lungs were hyperechoic, with the mediastinum shifted to the midline, diaphragm flattened, and the heart appearing compressed (Figures 1 and 2). In addition, an elongated hypoechoic structure in the posterior mediastinum was identified and thought to represent the fluid-filled esophagus (Figure 3). Polyhydramnios and a single umbilical artery were also detected. The patient underwent genetic counseling and amniocentesis, which revealed a normal male karyotype. Ultrafast fetal magnetic resonance imaging performed at 24 weeks showed a grossly normal fetal chest (sequences after balanced fast field-echo localizers consisted primarily of T2-weighted single-shot imaging with additional fast field-echo images).The initial ultrasound scan at our facility at 31 weeks revealed normal echogenicity of the lungs, and the previously described elongated hypoechoic structure in the posterior mediastinum was no longer detectable. Amniotic fluid volume was normal by 32 weeks of gestation, when pectus excavatum and right ventricular enlargement were also noted. Fetal echocardiography confirmed right ventricular enlargement and suspected pulmonary hypertension. A repeat ultrasound scan at 35 weeks yielded no additional relevant information. Biometry indicated appropriate fetal growth, with an estimated fetal weight at the 39th percentile for dates.The mother had no significant personal or family history. The current pregnancy was complicated by dietcontrolled gestational diabetes and late-onset gestational hypertension. She was admitted for labor induction at 38 weeks of gestation after spontaneous rupture of membranes. Ten hours after admission, a nonreassuring fetal heart rate pattern necessitated a primary low-transverse Cesarean delivery under lumbar epidural anesthesia. A liveborn male infant weighing 2655 g

Unanticipated Difficult Airway in a Neonate: Are we Prepared for this CHAOS?

“…Congenital high airway obstruction syndrome is characterised by a dilated trachea, hyperechoic lungs, flattened diaphragm, foetal ascites and polyhydramnios on the antenatal care scan (1). If diagnosed antenatally, these patients can undergo the Ex utero Intrapartum Treatment procedure, and the airway can be secured by either intubation or tracheostomy (3).…”

“…C ongenital high airway obstruction syndrome (CHAOS) is caused by defective canalisation of the upper airways around the 10 th week of gestation (1). Congenital subglottic stenosis is one of the aetiologies of CHAOS, with an incidence of <0.2% (2).…”

Evaluation of Fetal Vocal Cords to Select Candidates for Successful Fetoscopic Treatment of Congenital High Airway Obstruction Syndrome: Preliminary Case Series

“…Fetal surgery was performed at 21.2 weeks by means of a similar procedure to FETO for CDH [9]. Under maternal epidural and fetal intramuscular analgesia and immobilization as previously described, a 3-mm trocar was percutaneously introduced into the amniotic cavity and directed towards the mouth of the fetus.…”

“…Although laryngeal atresia seems to be the rule in CHAOS, airway obstruction may rarely be the consequence of an isolated stenosis, or even a membrane-like web [9]. In these fetuses, laryngeal anatomy is preserved and consequently deobstruction should lead to full recovery of normal lung development.…”

Fetal Bronchoscopy as a Useful Procedure in a Case with Prenatal Diagnosis of Congenital Microcystic Adenomatoid Malformation

“…Although previous reports have documented that in rare cases of fetal lung masses spontaneous lung decompression may occur with a progressive decrease in lung volumes and disappearance of diaphragmatic inversion [10], perinatal prognosis depends on the size of the mass, the degree of lung developmental impairment and the presence of cardiac dysfunction [11]. Thus, in the presence of hydrops or severe lung hypoplasia, fetal or neonatal mortality is as high as 100% with expectant management [4].…”