NBRC Registered Respiratory Therapist – Neonatal Pediatric Specialty (RRT-NPS) Practice Test

What is the normal range for cardiac index (CI)?

1.0-2.0 L/min/m2 2.5-5.0 L/min/m2 3.5-6.5 L/min/m2 0.5-1.5 L/min/m2

Correct Answer:

2.5-5.0 L/min/m2

Explanation:

Cardiac index shows how well the heart pumps relative to body size, calculated as CO divided by body surface area. The normal range is about 2.5 to 5.0 L/min per square meter. This normalization lets us compare heart performance across different ages and sizes. Values below 2.5 suggest inadequate perfusion or reduced cardiac output for the body's needs, while values above 5.0 indicate a hyperdynamic state or excessively high output. Exact cutoffs can vary with age and measurement method, but 2.5–5.0 is the commonly cited normal range.

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