In Tetralogy of Fallot, which sign is commonly observed during a cyanotic spell (tet spell)?

• A. Murmur
• B. Cyanosis
• C. Tachypnea
• D. Bounding pulses

Answer: (C)

During a tet spell, the obstruction of the right ventricular outflow tract increases right-to-left shunting, which severely reduces pulmonary blood flow and causes hypoxemia. The body's natural response to low oxygen is to breathe faster, so tachypnea becomes a prominent sign. You’ll often see the child develop rapid, shallow breathing as the spell progresses. Cyanosis will be present and typically worsens, and the harsh murmur from RVOT obstruction can become softer during a spell due to reduced flow. Bounding pulses aren’t the characteristic finding here. Recognizing the rapid breathing in this context helps differentiate a tet spell and guides immediate measures like soothing the child, placing them in a knee-chest position to raise systemic vascular resistance, and providing supplemental oxygen to improve oxygen delivery.