Definition

Hypoxic spells refer to a condition where a child's skin becomes slightly blue for a brief period. This condition is also known by other terms, such as tet spell, hypercyanotic spell, cyanotic spell, or paroxysmal dyspnea. The bluish color of the skin occurs due to a rapid drop in oxygen levels in the blood (hypoxia), caused by decreased blood flow to the lungs. This condition usually lasts less than a minute. Hypoxic spells are most commonly seen in children under 2 years old (especially between 2 and 4 months), typically after waking in the morning or after crying, and are very rare in adults. In some cases, hypoxic spells can resolve on their own without any intervention (self-limiting).

Hypoxic spells are usually caused by an underlying congenital heart disease, most commonly Tetralogy of Fallot (hence also referred to as Tet Spells). Tetralogy of Fallot is a relatively rare congenital heart defect involving a combination of four heart abnormalities: a large ventricular septal defect (a hole in the wall separating the left and right ventricles), obstruction of the pulmonary valve (the valve between the right ventricle and the pulmonary artery), right ventricular hypertrophy (enlargement of the right ventricle), and an overriding aorta (a shift in the position of the aorta).

Causes

Hypoxic spells occur when blood flow to the lungs suddenly decreases, resulting in less oxygen in the blood. Oxygen-rich blood appears bright red, while blood with lower oxygen levels looks darker and bluish. This low oxygen blood causes the skin to turn blue. The exact mechanism of the sudden decrease in blood flow to the lungs during a hypoxic spell is not well understood. However, several triggers are believed to cause this reduction in blood flow, including:

• Crying
• Bowel movements
• Waking from sleep
• Breastfeeding or bottle-feeding
• Fever
• Bathing
• Stress or anxiety
• Dehydration
• Rapid heart rate
• Use of certain medications, such as ACE inhibitors

Risk Factor

The main risk factor for hypoxic spells is having an underlying congenital heart disease, most commonly Tetralogy of Fallot. Several factors can increase the risk of your baby developing Tetralogy of Fallot, including:

• History of viral infections during pregnancy, such as Rubella (German measles)
• Alcohol consumption during pregnancy
• Poor nutrition during pregnancy
• Maternal age over 40
• Family history of Tetralogy of Fallot
• The presence of Down syndrome or DiGeorge syndrome in the baby

In addition to Tetralogy of Fallot, the risk of hypoxic spells can also increase with other heart defects, such as:

• Double-outlet right ventricle with pulmonary valve stenosis (both the aorta and pulmonary artery emerge from the right ventricle)
• Pulmonary valve atresia with a ventricular septal defect (absence of the pulmonary valve along with a heart defect)
• Tricuspid atresia with pulmonary stenosis (absence of the tricuspid valve along with a defect in the pulmonary artery)
• Transposition of the great arteries with ventricular septal defect and pulmonary stenosis (congenital heart defect where the aorta and pulmonary arteries are swapped in position)

Symptoms

Symptoms of hypoxic spells may include:

• Rapid and deep breathing
• Bluish discoloration, especially around the lips, mouth, face, and nails (cyanosis)
• Fussiness, restlessness, or discomfort
• Prolonged crying
• Fainting
• Decreased intensity or absence of heart murmurs

Diagnosis

Hypoxic spells are a medical emergency requiring immediate attention. A doctor may conduct a full examination once the child's condition has stabilized after receiving first aid. Hypoxic spells are often easily recognized by their clinical appearance.

To diagnose hypoxic spells, a doctor will ask about symptoms and any history of congenital heart disease, as well as the baby's condition at birth (whether the baby cried immediately or appeared blue). The doctor will perform a thorough physical examination, checking for blue discoloration and listening to the heart using a stethoscope. Additional tests may be recommended to diagnose any underlying heart defects, most commonly Tetralogy of Fallot, including:

• Pulse oximetry to measure oxygen levels in the blood using a small sensor placed on the finger or toe.
• Echocardiogram to create images of the heart using sound waves, showing the structure, location, and function of the heart, chambers, valves, and arteries.
• Electrocardiogram (ECG) to record the heart’s electrical activity during contractions, helping to detect heart enlargement or abnormal rhythms (arrhythmias).
• Chest X-ray to view the structure of the heart and lungs. A typical sign of Tetralogy of Fallot on an X-ray is a boot-shaped heart due to right ventricular enlargement.
• Cardiac catheterization to evaluate heart structure and plan for surgery. During this procedure, a thin flexible tube (catheter) is inserted into a blood vessel, usually in the groin, and guided to the heart. A dye may also be used to visualize the heart structures more clearly on X-rays, and the doctor can measure pressure and oxygen levels in the heart and blood vessels.

Management

Hypoxic spells require immediate treatment to prevent complications. Although the condition may seem frightening for both children and parents, it usually lasts less than a minute. If your child shows signs of a hypoxic spell, you can take the following steps:

• Stay calm and do not panic.
• Turn your child onto their side or back.
• Bring their knees up to their chest (knee-chest position).
• Some children may instinctively squat during a hypoxic spell, which also helps achieve the knee-chest position.
• Calm your child by touching or holding them.
• Make sure you can see your child’s face to monitor changes in skin color, alertness, and the duration of the episode.

If these initial steps do not help, a doctor may administer medications, intravenous fluids, or even surgery. In addition to managing hypoxic spells, the underlying congenital heart disease should also be treated.

Complications

If not treated promptly, hypoxic spells can lead to complications such as paralysis, seizures, neurological problems, and even death.

Prevention

There is no known way to completely prevent hypoxic spells, but managing the underlying congenital heart disease can reduce the risk. It is also recommended to avoid conditions that may trigger a hypoxic spell.

When to See a Doctor?

If your child experiences a hypoxic spell, take the initial steps for treatment. If there is no improvement, take your child to the emergency department immediately for further assistance.