Overview
This lecture explains central venous pressure (CVP), its physiological significance, normal values, clinical implications, and interventions for high or low CVP in critical care.
What is Central Venous Pressure (CVP)?
- Central venous pressure (CVP) measures the pressure at the cavo-atrial junction (where the superior/inferior vena cava meets the right atrium).
- CVP reflects pressure exerted by blood volume on the walls of the central veins.
- The measurement helps assess the volume of venous blood returning to the heart.
- Normal CVP range is 2–6 mmHg.
CVP and Cardiac Physiology
- The heart has four chambers: right/left atria and right/left ventricles.
- The superior and inferior vena cava return deoxygenated blood to the right atrium.
- CVP is directly related to preload, the volume/stretch in the ventricle before contraction.
Elevated CVP (CVP >6 mmHg)
- High CVP indicates fluid overload in the vascular system.
- Causes include congestive heart failure (CHF) where the heart cannot effectively eject blood.
- Symptoms may include third-spacing (e.g., pitting edema).
- Treatment includes diuretics like furosemide to remove excess fluid.
Low CVP (CVP <2 mmHg)
- Low CVP suggests hypovolemia (decreased circulating blood volume).
- Causes include hemorrhagic shock or GI bleeding leading to fluid loss.
- Results in decreased preload and poor return of blood to the right heart.
- Treatment involves fluid resuscitation (IV fluids, blood products, or albumin).
CVP in Critical Care
- CVP is used in intensive care to monitor patients’ fluid status, especially during significant fluid or medication administration.
- Monitoring CVP helps guide intervention for both fluid overload and depletion.
Key Terms & Definitions
- Central Venous Pressure (CVP) — the pressure in the central veins at the cavo-atrial junction.
- Preload — the volume of blood stretching the ventricle at the end of diastole (before contraction).
- Cavo-atrial junction — area where the superior/inferior vena cava meets the right atrium.
- Fluid overload — excess fluid volume in the body’s vasculature.
- Hypovolemia — reduced blood volume.
- Diuretic — medication that increases urine production to remove excess fluid.
- Albumin — plasma protein given to increase intravascular fluid volume.
Action Items / Next Steps
- Review normal CVP values and associated clinical implications.
- Study the relationship between CVP and cardiac preload.
- Understand interventions for abnormal CVP (diuretics for high CVP, fluids/blood for low CVP).