Preload

Increased

Normal CVP: 4-10 mm Hg

Decreased

Normal CVP: 4-10 mm Hg
Mechanism / Effect
  • Myocardial muscle fiber undergoes increased “stretch” which leads:
    • Increased ventricular blood volume
    • Increased stroke volume
    • Increased cardiac output
    • Increased ventricular work
  • Overstretched myocardial muscle fibers leads to:
    • Decreased force of contraction
    • Decreased stroke volume
    • Heart failure (Frank-Starling phenomenon)
Causes
  • Decreased fluid excretion (renal failure)
  • Fluid administration (fluid overload)
  • Ineffective cardiac pumping (right & left heart failure)
  • Aortic insufficiency (aortic stenosis / aortic prolapse)
  • Vasoconstriction (alpha stimulation
  • Inotropic medication
  • Pregnancy
Treatment
  • Correct condition causing fluid volume retention / overload
  • Vasodilation
  • Diuretics
    • Furosemide
    • Bumetanide
    • Mannitol (osmotic)
    • Spironolactone (K+ sparing)
    • Chlorothiazide
    • Hydrochlorothiazide
    • Metalazone
    • Edecrin
  • Continuous renal replacement therapy (CRRT) for fluid overload with renal failure (removes 50-100 ml/hr + waste)
Mechanism / Effect
  • Myocardial muscle fiber undergoes decreased stretch from decreased circulating blood volume leading to:
    • Decreased stroke volume
    • Decreased cardiac output
    • Vascular volume depletion
    • Hypotension
    • Cardiovascular collapse
Causes
  • Vascular volume loss
    • Hemorrhage
    • Diarrhea
    • Vomiting
    • Burns (weeping through burns due to no protective layer)
    • Edema (3rd spacing)
  • Vasodilation
    • Medications
    • Septic shock
  • Loss of atrial kick
Treatment
  • Correct condition causing fluid volume loss
  • Volume expansion
    • Normal Saline
    • Lactated Ringers
    • Albumin
    • Plasma
    • RBC’s
  • Vasoconstrictors (only a temporary fix, fluid replacement is still needed)
    • Epinephrine
    • Norepinephrine
    • High dose dopamine