Page 342 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

334 FLUID THERAPY

consumption, gastrointestinal losses (e.g., vomiting, diar- chloride, sodium, and potassium ions and development
rhea), urinary losses (i.e., polyuria), and traumatic losses of metabolic acidosis) (Table 14-3).
(e.g., blood loss, extensive burns) should be obtained
from the owner. Excessive insensible water losses (e.g., PHYSICAL EXAMINATION
increased panting, pyrexia) and third-space losses may The physical findings associated with fluid losses of 5% to
be determined from the history and physical examination. 15% of body weight vary from no clinically detectable
In addition, the clinician’s knowledge of the suspected changes (5%) to signs of hypovolemic shock and
disease can aid in predicting the composition of the fluid impending death (15%) (Table 14-4). 7,11,20 The clinician
lost (e.g., vomiting caused by pyloric obstruction leads to may estimate the hydration deficit by evaluating skin tur-
loss of hydrogen, chloride, potassium, and sodium ions gor or pliability, the moistness of the mucous membranes,
and development of metabolic alkalosis, whereas small the position of the eyes in their orbits, heart rate, charac-
bowel diarrhea typically leads to loss of bicarbonate, ter of peripheral pulses, capillary refill time, and extent of

TABLE 14-3 Potential Fluid, Electrolyte, and Acid-Base Disturbances in Various
Diseases and Suggested Crystalloid Solutions
Type of Electrolyte Acid-Base
Abnormality Dehydration Balance Status Fluid Therapy

Simple dehydration, Hypertonic — — Half strength or balanced
stress, exercise electrolyte solution; 5%
dextrose solution
þ
Heat stroke Hypertonic K variable, Metabolic acidosis Half strength electrolyte
þ
Na variable solution followed by balanced
electrolyte solution
Anorexia Isotonic Kþ loss Mild metabolic Balanced electrolyte solution;
acidosis KCl
þ
Starvation Isotonic K loss Mild metabolic Half strength or balanced
acidosis electrolyte solution; KCl;
calories
þ
þ
Vomiting Isotonic or hypertonic Na ,K , and Cl Metabolic alkalosis; Ringer’s solution; 0.9% saline
loss metabolic acidosis with KCl supplementation
chronically
þ
þ
Diarrhea Isotonic or hypertonic Na loss, K loss Metabolic acidosis Balanced electrolyte solution;
chronically HCO 3 ; KCl (if chronic)

Diabetes mellitus Hypertonic K loss Metabolic acidosis Balanced electrolyte solutions;
þ
KCl
þ
Hyperadrenocorticism Isotonic K loss Occasionally mild Balanced electrolyte solutions;
metabolic alkalosis KCl
þ
Hypoadrenocorticism Isotonic or hypertonic Na loss, K þ Metabolic acidosis 0.9% saline followed by balanced
Retention electrolyte solutions
þ
Urethral obstruction Isotonic or hypertonic K retention; Metabolic acidosis 0.9% saline followed by balanced
þ
Na ,Cl electrolyte solutions; KCl
variable postobstruction
þ
Acute renal failure Isotonic or hypertonic K retention; Metabolic acidosis Balanced electrolyte solutions
(with vomiting) Na ,Cl
þ
variable
Chronic renal failure Isotonic or hypertonic Na ,K ,Cl Metabolic acidosis Balanced electrolyte solutions
þ
þ
(with vomiting) variable
Congestive heart Plethoric (Na ,H 2 O Na retention (but Metabolic acidosis 5% dextrose solution
þ
failure retention early; dilutional (chronically)
hypotonic chronically) hyponatremia)
Hemorrhagic shock Isotonic Metabolic acidosis Balanced electrolyte solutions;
blood
Endotoxic shock Isotonic Metabolic acidosis Balanced electrolyte solutions;
0.9% saline
From Muir WW, DiBartola SP. Fluid therapy. In: Kirk RW, editor. Current veterinary therapy VIII. Philadelphia: WB Saunders, 1983: 31.