Fluid Therapy for Heart Failure (Box 44.12)
K. Gary Magdesian
The cardiac patient represents a unique challenge to fluid therapy. Volume expansion poses significant risk to the horse with heart failure by raising venous pressures (edema risk) and potentiating sodium retention.
Administration of sodium-containing fluids can lead to or compound edema and body cavity effusions. Despite these risks, patients with heart failure sometimes require fluid therapy, such as when they develop anorexia, renal failure, or diarrhea. Monitoring of CVP should be performed in these patients at a referral center in order to aid in prevention of edema. Initial fluid therapy should consist of conservative rates, with frequent reassessment of the effects of fluids on the patient. Continuous, slow administration of fluids, rather than boluses, should be used to avoid rapid swings in CVP. Any rise in CVP should be avoided in horses with heart failure.The choice of fluid depends largely on concerns over sodium retention in the patient with heart failure. Fluids with lower sodium content may be preferable for maintenance fluid therapy, such as maintenance fluids (0.45% NaCl/2.5% dextrose, Plasma- Lyte 56, or combinations of isotonic replacement fluids mixed with sterile water in a 1 : 1 ratio). As soon as the patient is able to drink water, the intravenous fluids should be discontinued.
Because of sodium retention in heart failure, these horses are often treated with diuretics such as furosemide, which aid in minimizing edema formation.1 A fine balance between fluid therapy and diuretics is required.
■ BOX 44.12
Fluid Guidelines for Heart Failure