What are normal hemodynamic values, and what do CVP, PA pressures, cardiac output and SVR tell you?

What are normal hemodynamic values?

Normal hemodynamic values are reference ranges, not targets. The table below shows commonly published adult ranges used for teaching. These are typical published adult reference figures used for teaching, not orders; confirm every value against your facility's approved references.

Institutions differ, and the number that matters most is always this patient's trend against this patient's own baseline. A single value in isolation tells you far less than the direction it is moving.

Every number on the screen should also be read alongside urine output, lactate, mentation and skin perfusion, never alone.

What does CVP tell you?

CVP, also listed as right atrial pressure (RAP), is one of your preload (filling pressure) numbers. A high CVP suggests volume overload, right ventricular failure, tamponade, pulmonary embolism or high PEEP. A low CVP suggests hypovolemia or vasodilation.

CVP becomes most useful when you compare it with the wedge pressure. A CVP that is disproportionately high relative to the PAOP is one of the classic signs of right ventricular failure, the pattern people miss.

Findings that point toward RV failure include:

• High CVP with a low or normal wedge and low cardiac output
• Elevated PVR
• Hypotension that worsens with volume loading
• Distended neck veins with clear lungs
• Poor response to inotropes aimed only at the left ventricle

RV failure is not treated the same way as LV failure. It is common after inferior MI, in pulmonary hypertension and after cardiac surgery, and these patients can get worse with aggressive fluid, so this pattern is worth raising with the provider early.

What do PA pressures and the wedge pressure tell you?

Pulmonary artery pressures and the wedge (PAOP) are measured through a pulmonary artery (Swan-Ganz) catheter; together with CVP, the wedge is one of your preload (filling pressure) numbers. They are measured through a pulmonary artery (Swan-Ganz) catheter.

• PA systolic: high values suggest pulmonary hypertension, LV failure or hypoxia; low values suggest hypovolemia.
• PA diastolic: high values suggest LV failure or volume overload; low values suggest hypovolemia.
• Mean PAP: a high value suggests pulmonary hypertension.
• PAOP / wedge: high values suggest LV failure, mitral disease or volume overload; low values suggest hypovolemia.

Together, CVP and the wedge are your preload numbers. When both are high with a low cardiac index and a high SVR, the picture is pump failure. When both are low with a low index and high SVR, the problem is usually not enough volume.

The balloon only goes up long enough to get the measurement. Prolonged wedging risks pulmonary artery rupture and infarction, so allow passive deflation and confirm the PA waveform returns. A spontaneously wedged tracing is an emergency finding: the catheter has migrated and the physician needs to know immediately.

What do cardiac output and cardiac index tell you?

Cardiac output tells you how much blood the heart moves each minute, and cardiac index tells you the same thing corrected for body size. Cardiac index (CI = CO ÷ BSA) is the more honest number and the one that drives decisions.

Cardiac output equals heart rate times stroke volume (CO = HR × SV). Only two levers exist, and everything you titrate moves one of them. Stroke volume in turn depends on preload, afterload and contractility, and every vasoactive drug acts on one of those three.

A high cardiac output or index suggests sepsis or another hyperdynamic state. A low one suggests a low output state such as cardiogenic shock or hypovolemia.

Mixed venous oxygen saturation (SvO2) adds context: it reflects oxygen supply versus demand, and a falling SvO2 often changes before blood pressure does. A low SvO2 points toward low output, anemia, hypoxemia or increased demand.

What does SVR tell you, and why can blood pressure mislead you?

SVR (systemic vascular resistance) tells you how constricted or dilated the systemic vessels are. A high SVR suggests vasoconstriction, cardiogenic shock or hypovolemia. A low SVR suggests sepsis, vasodilation or anaphylaxis.

SVR matters because mean arterial pressure is roughly cardiac output times SVR (MAP ≈ CO × SVR). Blood pressure is a product of flow and resistance, so a patient can be profoundly under-perfused with a completely acceptable blood pressure because resistance is carrying the number.

That is why an adequate MAP with a low cardiac index and a rising lactate means flow failure hidden by resistance. Cardiac index, lactate, urine output, mentation and SvO2 tell you about flow. Learn to distrust an isolated MAP.

SVR also separates the shock states. Hypovolemic, cardiogenic and obstructive shock tend to show a high SVR with low output, while early septic (distributive) shock shows a low SVR with a high or normal output. Obstructive shock (tamponade, massive PE, tension pneumothorax) can look cardiogenic, and the difference matters because the treatment is mechanical, not pharmacologic.

How do you make sure hemodynamic numbers are accurate?

Level and zero before you believe any number. The transducer is leveled to the phlebostatic axis and zeroed to atmosphere, and it needs re-leveling with every position change. A transducer that has drifted with the head of the bed is the most common source of false hemodynamic data in the ICU.

1. Read at end-expiration, where intrathoracic pressure has the smallest influence.
2. Read from the graphic waveform, not the digital number, whenever the two disagree.
3. Use a square-wave test to confirm the system is neither over- nor underdamped.

An overdamped arterial tracing underestimates systolic pressure and looks blunted, often from air, clot, a kink or a loose connection. An underdamped tracing overestimates systolic pressure with an exaggerated overshoot, often from tubing that is too long or excess stopcocks.

When you present on rounds, state the pattern rather than the parade of numbers. "Filling pressures are up, index is down, SVR is high, lactate is climbing, this looks cardiogenic" is a clinical assessment that gets you taken seriously.

The full reference, built for the pocket

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This article is educational reference material for licensed clinicians and students, drawn from a Cardiac Nurse Playbooks guide. It is not medical advice, not a protocol, and not a substitute for your facility's policies, physician orders, device manufacturer instructions for use, or current drug references. Any values shown are typical published reference figures; verify every dose, setting and parameter against your facility's approved sources. When this and your unit policy disagree, your unit policy wins.