# A 2-year-old toddler with tetralogy of Fallot is brought to the emergency department with a history of cyanotic spells. The child is currently calm but has clubbing of fingers and toes. What is the most likely finding on physical exam?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=541972  
> language: ko  
> subject: Child Health

## 문제

A 2-year-old toddler with tetralogy of Fallot is brought to the emergency department with a history of cyanotic spells. The child is currently calm but has clubbing of fingers and toes. What is the most likely finding on physical exam?

## 보기

1. Systolic ejection murmur at the left upper sternal border **✔ 정답**
2. Place the infant in a supine position with legs elevated
3. Place the infant in knee-chest position to increase systemic vascular resistance
4. Right ventricular heave

**정답: 1**

## 해설

Clubbing indicates chronic hypoxia. In a calm toddler with tetralogy of Fallot, the most likely physical exam finding is a systolic ejection murmur at the left upper sternal border due to pulmonary stenosis. Other options are less specific or not typical.

## 심화 해설

Clinical Judgment
This question asks about the priority nursing intervention during a life-threatening hypercyanotic spell ("Tet Spell") in an infant with Tetralogy of Fallot. The key judgment point is the pathophysiology of the spell and the method for immediate hemodynamic improvement. The spell occurs when worsening pulmonary stenosis drastically reduces pulmonary blood flow and increases right-to-left shunting through the ventricular septal defect, causing severe hypoxemia. The most critical action is to increase systemic vascular resistance (SVR) to promote blood flow through the pulmonary artery. The knee-chest position, which involves bending the knees up toward the chest, is the quickest and most effective way to increase peripheral vascular resistance. This position is the first-line intervention that can be performed immediately without medication or complex equipment.

Memory Tip: **T**et Spell = **T**uck (knees to chest). Remember "**K**nee to **C**hest for **C**yanosis **C**ontrol."

KR vs US: In Korea, the 'knee-chest position' is also called the 'squatting position,' and the basic principle is the same. In the US NGN, questions frequently emphasize the priority of immediate, non-pharmacological interventions based on this physiological principle.

## 임상 시나리오

Clinical Practice Guide
1.  Cyanotic Spell Management Protocol: Knee-chest position → Provide supplemental oxygen → Sedation (morphine) → Beta-blocker (propranolol) → Administer sympathomimetic agent (phenylephrine) if needed → Prepare for surgical treatment.
2.  Parent Education: It is important to teach them to recognize early signs of a spell (irritability, crying, worsening cyanosis, respiratory distress) and to assume the knee-chest position at home.

Caution: In SATA (Select All That Apply) questions asking for "all interventions to perform immediately during a cyanotic spell," the knee-chest position, oxygen provision, and sedation are included, but 'prepare for immediate endotracheal intubation' can be a trap as it is a step after initial interventions fail. Also, the 'supine position with legs raised' is absolutely contraindicated as it can lower SVR.

## 핵심 개념

- **Tetralogy of Fallot** — Tetralogy of Fallot. A cyanotic congenital heart disease that combines four cardiac anomalies (ventricular septal defect, pulmonary stenosis, right ventricular hypertrophy, overriding aorta).
- **Hypercyanotic Spell (Tet Spell)** — Life-threatening acute cyanotic episodes in patients with tetralogy of Fallot. These are caused by a sudden decrease in pulmonary blood flow, leading to severe hypoxemia.
- **Knee-Chest Position** — Knee-chest position. An emergency posture where the infant's knees are bent and brought toward the chest to increase systemic vascular resistance and promote blood flow through the pulmonary artery.
- **Systemic Vascular Resistance** — Systemic vascular resistance. The resistance of peripheral blood vessels that the left ventricle must overcome to eject blood. During a Tet spell, increasing SVR increases pulmonary blood flow.
- **Right-to-Left Shunt** — Right-to-left shunt. Abnormal blood flow where deoxygenated venous blood flows toward the left heart (arterial blood). It is the main pathophysiology of Tetralogy of Fallot, causing cyanosis.

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