Noninvasively estimate RAP from IVC diameter and collapsibility. Which statement correctly describes the typical cutoffs?

• A. RAP is estimated from IVC diameter alone, ignoring collapsibility.
• B. IVC ≤ 2.1 cm with >50% collapse → RAP 0–5 mmHg; IVC > 2.1 cm with <50% collapse → RAP 10–20 mmHg; intermediate 5–10 mmHg.
• C. RAP cannot be estimated noninvasively.
• D. IVC diameter alone determines RAP.

Answer: (B)