How Are Breathing Problems Evaluated in Trisomy 18?

In babies with trisomy 18, breathing difficulty can be caused by the brain (central apnea), the physical airway (obstruction), the lungs, the heart, swallowing problems (aspiration), or an acute illness like an infection. Because these issues often overlap, doctors use a combination of physical observation, oxygen and carbon-dioxide monitoring, sleep studies, airway endoscopy, chest X-rays, and echocardiograms to pinpoint the most likely contributors. Identifying the root cause is critical for tailoring treatment to your child’s specific needs and aligning care with your family’s overall goals, whether that means intensive intervention or focusing on your baby’s comfort.

Warning Signs and Emergency Action

Severe breathing trouble is a medical emergency. Respiratory failure and apnea are leading causes of infant mortality in trisomy 18 ^[1]. If your baby experiences severe difficulty breathing (such as grunting, flaring nostrils, or chest retractions), prolonged pauses in breathing, turns blue or gray (cyanosis), or becomes limp or unresponsive, you must act immediately.

• Follow your child’s individualized emergency care plan.
• Call emergency services for severe distress, persistent cyanosis, or unresponsiveness, unless your documented care plan explicitly directs a comfort-focused response.
• Do not attempt to use treatments like supplemental oxygen, high-flow nasal cannula therapy, or positive-pressure ventilation (such as CPAP or bag-mask ventilation) unless they have been specifically prescribed for your baby and you have been trained to use them ^[2][3].

Understanding the Causes

Central Apnea, Seizures, and Acute Illness

Apnea is a pause in breathing. In central apnea, the brain temporarily stops sending signals to the breathing muscles. Apnea is common in newborns with trisomy 18, often beginning within the first few days of life ^[2]. However, any new or worsening apnea must be evaluated for acute, reversible causes like infection (sepsis), low blood sugar, or temperature instability.

Rarely, breathing pauses are caused by hidden seizures (epileptic apnea). If doctors suspect this, they may use a continuous or video electroencephalogram (EEG) to monitor brain waves; if seizures are confirmed, anti-seizure medications can treat the seizure-related apnea and stabilize oxygen levels ^[4].

Airway Obstruction

Babies with trisomy 18 often have physical features that can block the upper airway, such as a small jaw (micrognathia), a tongue that falls back in the throat (glossoptosis), or low muscle tone (hypotonia) ^[5]. They may also have soft, floppy airway tissue that narrows during breathing, such as laryngomalacia or tracheomalacia ^[6]. Warning signs of an airway problem include snoring, noisy breathing, or struggling to breathe while sleeping (sleep-disordered breathing) ^[5].

Heart Failure and Lung Disease

Congenital heart defects, such as a hole between the heart’s lower chambers (ventricular septal defect or VSD), are frequent in trisomy 18 ^[7]. Depending on the size of the defect, it can cause excessive blood flow to the lungs, leading to heart failure and high blood pressure in the lungs (pulmonary hypertension) ^[8][9]. Some babies with cyanotic heart defects naturally have a lower baseline oxygen level. Warning signs of heart failure include fast breathing, sweating or tiring with feeds, poor weight gain, and fewer wet diapers ^[8].

Swallowing Issues and Aspiration

Feeding difficulties and swallowing dysfunction (dysphagia) are widespread in trisomy 18 ^[6][10]. When a baby has trouble swallowing, milk, saliva, or stomach acid (from acid reflux) can enter the lungs—a process called aspiration. This can cause recurrent lung infections or pneumonia ^[11]. Importantly, aspiration can be silent, meaning the baby may not cough or choke when it happens. Never change your baby’s feeding position, formula thickness, or feeding method without consulting your care team.

How Doctors Evaluate Breathing Issues

Not every baby will need every test; clinicians select tests based on the urgency, the symptoms, and the family’s goals of care.

• Observation and Monitoring: Doctors monitor oxygen levels using a pulse oximeter (a sensor on the finger or toe) and carbon dioxide levels using specialized monitors to evaluate breathing effectiveness ^[3]. At home, prescribed monitors can be helpful, but they can give false alarms and do not replace observing your baby directly.
• Airway and Sleep Evaluation: An Ear, Nose, and Throat (ENT) specialist may perform an airway endoscopy (using a tiny camera to look inside the throat and windpipe) to check for physical blockages or floppy cartilage ^[12]. A sleep study (polysomnography) measures breathing, oxygen, heart rate, and brain activity overnight to determine if breathing pauses are central or obstructive ^[5].
• Imaging and Heart Tests: A chest X-ray (radiography) can show an enlarged heart or fluid and infection in the lungs ^[8][13]. An ultrasound of the heart (echocardiography) checks for structural heart defects and evaluates heart function ^[8].
• Feeding Assessment: If aspiration is suspected, a feeding specialist or speech-language pathologist will observe a feed. If clinically appropriate, they may perform a specialized swallow study (such as a videofluoroscopy) to see exactly where the liquid goes ^[6].