# A 6-month-old infant with a large ventricular septal defect (VSD) is admitted with signs of congestive heart failure. The infant weighs 5.5 kg and has been receiving digoxin 0.01 mg/kg/day divided into two doses. Which nursing intervention is the priority when caring for this infant? > source: MyMerci (mymerci.kr) > url: https://mymerci.kr/pages/nclex_q.php?qn_id=541956 > language: ko > subject: Child Health ## 문제 A 6-month-old infant with a large ventricular septal defect (VSD) is admitted with signs of congestive heart failure. The infant weighs 5.5 kg and has been receiving digoxin 0.01 mg/kg/day divided into two doses. Which nursing intervention is the priority when caring for this infant? ## 보기 1. Administer oxygen at 6 L/min via nasal cannula 2. Position the infant in Trendelenburg position to improve venous return 3. Monitor for signs of digoxin toxicity such as bradycardia or feeding intolerance **✔ 정답** 4. Encourage increased fluid intake to prevent dehydration from diuretic therapy **정답: 3** ## 해설 Infants on digoxin for CHF have a narrow therapeutic window and immature renal function, making toxicity monitoring the priority to prevent life-threatening complications. Other interventions are important but secondary. ## 심화 해설 Clinical Context and Priority Setting This infant presents with a large ventricular septal defect (VSD) and congestive heart failure (CHF), managed with digoxin. Digoxin has a notoriously narrow therapeutic index, meaning the difference between a therapeutic dose and a toxic dose is very small. In infants, pharmacokinetics are further complicated by variations in birth weight, gestational age, and renal function, making therapeutic drug monitoring and clinical assessment for toxicity a critical safety priority [2]. Why Monitoring for Digoxin Toxicity is the Priority The correct answer is to monitor for signs of digoxin toxicity, specifically bradycardia and feeding intolerance. These are often the earliest clinical indicators of toxicity in this population. A case study of a premature infant with a left-to-right shunt (similar pathophysiology to a VSD) demonstrated that the earliest sign of digoxin toxicity was junctional bradycardia, which occurred even before serum digoxin levels reached the classic toxic range [1]. This underscores the principle that clinical assessment takes precedence over a single laboratory value. The nurse at the bedside is in the prime position to detect a dropping heart rate or a change in feeding behavior before a life-threatening dysrhythmia develops. Analysis of Incorrect Options - Option 1: Administer oxygen at 6 L/min via nasal cannula. This is not a priority and could be harmful. High-flow oxygen can cause pulmonary vasodilation, which, in the setting of a large VSD, can actually increase left-to-right shunting and worsen pulmonary overcirculation and CHF symptoms. Oxygen should be used cautiously and only when indicated by documented hypoxemia. - Option 2: Position the infant in Trendelenburg position. This is contraindicated. The Trendelenburg position (head down) increases venous return to the right side of the heart and can elevate intracranial pressure. In a patient with a VSD and CHF, this increased preload would further overload the already volume-burdened right ventricle and lungs, exacerbating heart failure symptoms. The correct positioning to reduce work of breathing and cardiac workload is typically a semi-Fowler's position. - Option 4: Encourage increased fluid intake to prevent dehydration. This is inappropriate for a patient in CHF. Fluid management in heart failure focuses on restriction, not encouragement of intake. Diuretics are used to offload excess fluid volume causing pulmonary congestion. The nursing intervention is to carefully monitor strict intake and output and daily weights, not to push fluids. Pathophysiology and Clinical Application The rationale for digoxin use in a large VSD is to improve myocardial contractility. However, the same pathophysiology that necessitates its use also increases the risk of toxicity. The left-to-right shunt activates the renin-angiotensin-aldosterone system (RAAS) as a compensatory mechanism. This can lead to hyperaldosteronism and severe hypokalemia, a state that massively potentiates digoxin's effects on the myocardium, triggering toxicity even when the serum digoxin level appears to be within a "normal" range [1]. Therefore, monitoring for clinical signs like a heart rate that drops below age-appropriate norms (e.g., < 90-110 bpm in an infant) or new-onset vomiting and poor feeding is the most direct and effective way to ensure patient safety.References (research sources) - [1]Junctional Bradycardia as Early Sign of Digoxin Toxicity in a Premature Infant with Congestive Heart Failure due to a Left to Right Shunt.Research articleDasgupta S, Aly AM, Jain SK. (2016) · DOI: 10.1055/s-0035-1567858 - [2]Predicting the serum digoxin concentrations of infants in the neonatal intensive care unit through an artificial neural network.Research articleYao SH, Tsai HT, Lin WL, Chen YC, Chou C, Lin HW. (2019) · DOI: 10.1186/s12887-019-1895-7 ## 임상 시나리오 Clinical Scenario A 6-month-old infant with a large ventricular septal defect (VSD) and congestive heart failure (CHF) is admitted. The infant weighs 5.5 kg and is receiving digoxin 0.01 mg/kg/day in two divided doses. Nursing Priority Guide - **Assess for Toxicity First:** Before each digoxin dose, check apical pulse for one full minute. Withhold if heart rate is below 90-100 bpm in infants and notify provider. - **Monitor Feeding:** Document intake, signs of fatigue during feeds, and any vomiting. Feeding intolerance is an early sign of digoxin toxicity in this age group. - **Fluid Management:** Do not encourage increased fluids. Infants with CHF are often on fluid restrictions to reduce cardiac workload. Strict intake and output monitoring is essential. - **Positioning:** Maintain semi-Fowler's or upright position to ease respiratory effort. Avoid Trendelenburg, which increases preload and worsens heart failure. - **Oxygen Therapy:** Use cautiously and only if ordered. High-flow oxygen can cause pulmonary vasodilation, increasing left-to-right shunting and exacerbating CHF in VSD. Key Safety Alert Digoxin has a narrow therapeutic index. Clinical signs of toxicity (bradycardia, vomiting) often precede elevated serum levels. Bedside assessment is the most critical safety intervention. ## 핵심 개념 - **Digoxin Toxicity** — A state of drug overdose due to digoxin's narrow therapeutic index, often presenting first in infants as bradycardia or feeding intolerance. - **Ventricular Septal Defect (VSD)** — A congenital heart defect characterized by an opening in the septum between the ventricles, causing left-to-right shunting and increased pulmonary blood flow. - **Narrow Therapeutic Index** — A small margin between a drug's effective dose and a toxic dose, requiring close monitoring of clinical signs and serum levels. - **Congestive Heart Failure (CHF)** — A condition where the heart cannot pump blood efficiently, leading to fluid buildup; in VSD, it results from volume overload due to the shunt. ## 같은 주제 문제 - [A 2-year-old toddler with a ventricular septal defect (VSD) is being assessed by the nurse…](https://mymerci.kr/pages/nclex_q.php?qn_id=541952) - [A 4-month-old infant with a ventricular septal defect (VSD) is brought to the pediatric cl…](https://mymerci.kr/pages/nclex_q.php?qn_id=541953) - [A 3-month-old infant with a ventricular septal defect (VSD) is brought to the pediatric cl…](https://mymerci.kr/pages/nclex_q.php?qn_id=541954) - [A 4-year-old child with tetralogy of Fallot is admitted to the pediatric unit with signs o…](https://mymerci.kr/pages/nclex_q.php?qn_id=541955) - [A 2-year-old toddler with a ventricular septal defect (VSD) is admitted to the pediatric u…](https://mymerci.kr/pages/nclex_q.php?qn_id=541957) - [A 6-month-old infant with a ventricular septal defect (VSD) is admitted to the pediatric u…](https://mymerci.kr/pages/nclex_q.php?qn_id=541958) - [A 6-month-old infant with tetralogy of Fallot is admitted to the pediatric unit with signs…](https://mymerci.kr/pages/nclex_q.php?qn_id=541959) --- More free questions: [기출문제](https://mymerci.kr/) _학습 참고용입니다. 실제 임상은 최신 지침과 소속 기관 프로토콜을 따르세요._