What does SVV mean?
stroke volume variation
in most patients this estimates LVEDP thus is an indicator of LVEDV (preload of the left ventricle) normally 6-12mmHg (1-5mmHg less than the pulmonary artery diastolic pressure) PCWP >18 mmHg in the context of normal oncotic pressure suggests left heart failure.
Parameter Normal value Cardiac Output (CO) 4-8 L/min Central Venous Pressure (CVP) (also known as Right Atrial Pressure (RA)) 2-6 mmHg Pulmonary Artery Pressure (PA) Systolic 20-30 mmHg (PAS) Diastolic 8-12 mmHg (PAD) Mean 25 mmHg (PAM) Pulmonary Capillary Wedge Pressure (PWCP) 4-12 mmHg
- Pulmonary hypertension is often caused by increased pulmonary vascular resistance. Pulmonary hypertension can also result from increases in pulmonary venous pressure and pulmonary blood volume secondary to left ventricular failure or mitral or aortic valve disease.
- Pulmonary blood pressure is normally a lot lower than systemic blood pressure. Normal pulmonary artery pressure is 8-20 mm Hg at rest. If the pressure in the pulmonary artery is greater than 25 mm Hg at rest or 30 mmHg during physical activity, it is abnormally high and is called pulmonary hypertension.
Stroke volume is determined by preload, contractility, and afterload. The normal range for cardiac output is about 4 to 8 L/min, but it can vary depending on the body's metabolic needs. Cardiac output is important because it predicts oxygen delivery to cells.
- Stroke volume is determined by preload, contractility, and afterload. The normal range for cardiac output is about 4 to 8 L/min, but it can vary depending on the body's metabolic needs. Cardiac output is important because it predicts oxygen delivery to cells.
- The central venous pressure (CVP) is the pressure measured in the central veins close to the heart. It indicates mean right atrial pressure and is frequently used as an estimate of right ventricular preload. The CVP does not measure blood volume directly, although it is often used to estimate this.
- The amount of blood put out by the left ventricle of the heart in one contraction is called the stroke volume. The stroke volume and the heart rate determine the cardiac output. A normal adult has a cardiac output of 4.7 liters (5 quarts) of blood per minute.
SvO2: mixed venous saturation SaO2: arterial oxygen saturation VO2: oxygen consumption Hg: hemoglobin. Q: cardiac output. From this equation, one can see that SvO2 varies directly with SaO2, Hg, cardiac output and inversely with VO2. The normal SvO2 is 65-75%, which denotes tissue oxygen extraction to be 25-35%.
- Normal values of mixed venous oxygen saturation (SvO2) are 60 - 80%. Central venous oxygen saturation (ScvO2) values represent regional venous saturations with a normal value of ~70%. ScvO2 usually measures slightly higher than SvO2 as it has not mixed with the venous blood from the coronary sinus.
- By the time the blood reaches the pulmonary artery, all venous blood has "mixed" to reflect the average amount of oxygen remaining after all tissues in the body have removed oxygen from the hemoglobin. The mixed venous sample also captures the blood before it is re-oxygenated in the pulmonary capillary.
- Normal mixed venous oxygen tension (PvO2) is approximately 40 mmHg, representing the balance between oxygen consumption and oxygen delivery. A true PvO2 measurement must come from a mixed venous blood sample containing venous drainage from the SVC, IVC, and the heart.
Updated: 4th October 2019