Canonical: https://echosuite.app/guides/rap/ # Right atrial pressure assessment: IVC and hepatic vein flow Review IVC and hepatic-flow inputs in EchoSuite’s right atrial pressure tool, with acquisition guidance and supporting reference context. Created by [Mohammed Kamareddine, MD](https://echosuite.app/about/) · [Sources & educational scope](https://echosuite.app/about/) [Open interactive calculator →](https://echosuite.app/calculators/#rap) ## Method RAP category from IVC diameter and inspiratory collapse Use the measurement units shown below. Some fields apply only to a selected method or condition; follow the interactive tool’s method choices. The interactive tool keeps missing measurements incomplete and provides its method-specific results and reference context. ## Measurements and acquisition ### Measurement Enter the measured value in the displayed unit - IVC estimate - Measured collapse - Hepatic S / D - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### IVC diameter cm Subcostal long axis · M-mode or 2D - From subcostal IVC long axis, measure end-expiratory diameter 0.5–3.0 cm proximal to the right-atrial ostium. - Keep the calipers perpendicular to the IVC and observe variation with both a sniff and quiet respiration. - Record whether inspiratory collapse is at least 50%; do not use collapse alone during positive-pressure ventilation. ### Collapse with sniff Subcostal long axis · M-mode or 2D - At least 50% - Less than 50% - From subcostal IVC long axis, measure end-expiratory diameter 0.5–3.0 cm proximal to the right-atrial ostium. - Keep the calipers perpendicular to the IVC and observe variation with both a sniff and quiet respiration. - Record whether inspiratory collapse is at least 50%; do not use collapse alone during positive-pressure ventilation. ### End-expiratory maximum cm Enter the measured value in the displayed unit - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Sniff minimum cm Enter the measured value in the displayed unit - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Same site and plane Enter the measured value in the displayed unit - Both walls tracked - Out-of-plane / uncertain - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Peak forward S cm/s Enter the measured value in the displayed unit - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Peak forward D cm/s Enter the measured value in the displayed unit - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Usable forward peaks Enter the measured value in the displayed unit - Yes - Systolic reversal - Uncertain / limited - Confirm the variable matches the selected formula. - Use the unit displayed beside the field. - Keep measurements from the same representative hemodynamic state. ### Ventilation Subcostal long axis · M-mode or 2D - Spontaneous breathing - Positive-pressure ventilation - From subcostal IVC long axis, measure end-expiratory diameter 0.5–3.0 cm proximal to the right-atrial ostium. - Keep the calipers perpendicular to the IVC and observe variation with both a sniff and quiet respiration. - Record whether inspiratory collapse is at least 50%; do not use collapse alone during positive-pressure ventilation. ### Secondary evidence when discordant Subcostal long axis · M-mode or 2D - None present - One or more present - Unavailable / uncertain - From subcostal IVC long axis, measure end-expiratory diameter 0.5–3.0 cm proximal to the right-atrial ostium. - Keep the calipers perpendicular to the IVC and observe variation with both a sniff and quiet respiration. - Record whether inspiratory collapse is at least 50%; do not use collapse alone during positive-pressure ventilation. ### Marked venous signs with IVC >2.5 cm Subcostal long axis · M-mode or 2D - No - Yes - From subcostal IVC long axis, measure end-expiratory diameter 0.5–3.0 cm proximal to the right-atrial ostium. - Keep the calipers perpendicular to the IVC and observe variation with both a sniff and quiet respiration. - Record whether inspiratory collapse is at least 50%; do not use collapse alone during positive-pressure ventilation. ## Sources and method context American Society of Echocardiography · 2025 · Guidelines for the Echocardiographic Assessment of the Right Heart in Adults and Special Considerations in Pulmonary Hypertension · RAP section and Figure 3 · PDF pp. 19–20 and 23 [Primary reference](https://www.asecho.org/wp-content/uploads/2026/08/ASE-Right-Heart-Guidelines-May-2025.pdf) - Primary IVC branches · RAP section and Table 4 · PDF pp. 19–20 End-expiratory IVC measurement, the 2.1-cm and 50% branches, and discrete 3, 8, 15, or selected 20-mmHg estimates. - Discordant findings and caveats · RAP section · PDF p. 19 Secondary-index resolution, positive-pressure ventilation limitations, and caveats for athletes, pregnancy, and inadequate sniff. Catalogue review status: Exact guideline locator mapped · clinical sign-off pending These pages describe the educational tool. 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