Question

The medical resident would now like to determine the patient's systemic vascular resistance index (SVRI). She asks you what values need to be measured in order to calculate the SVRI. You would respond that the following need to be measured:

1) Mean systemic arterial blood pressure, PAWP, cardiac output, and BSA.
2) Systemic arterial systolic and diastolic blood pressure, CVP, cardiac output, and BSA.
3) Systemic arterial systolic and diastolic blood pressure, PAWP, cardiac output, and BSA.
4) Mean systemic arterial blood pressure, CVP and cardiac index (CI).
5) Pulmonary arterial systolic and diastolic blood pressure, PAWP, and cardiac index (CI).

Answer 1

To determine the Systemic Vascular Resistance Index (SVRI), one must measure mean systemic arterial blood pressure, Pulmonary Artery Wedge Pressure (PAWP), cardiac output, and body surface area (BSA). The calculation uses mean arterial pressure and cardiac output adjusted for BSA (Cardiac Index). The formula for SVRI is: SVRI = ((MAP - CVP) × 80) / CI.

Step-by-step explanation:

To calculate the Systemic Vascular Resistance Index (SVRI), the correct values that need to be measured are:

1. Mean systemic arterial blood pressure
2. Pulmonary Artery Wedge Pressure (PAWP)
3. Cardiac Output (CO)
4. Body Surface Area (BSA)

It is important to understand that systemic arterial blood pressure is measured as a ratio of two numbers, expressed as systolic pressure over diastolic pressure. The systolic pressure is the higher value and reflects the arterial pressure during ventricular contraction. Mean arterial pressure (MAP) is derived from systolic and diastolic pressures and is used in the calculation of SVRI, which is a critical parameter in assessing the afterload of the heart.

The formula for calculating SVRI is as follows:

SVRI = ((MAP - CVP) × 80) / Cardiac Index (CI)

Where MAP is mean arterial pressure, CVP is central venous pressure, and CI is cardiac index which is cardiac output normalized for BSA.