Page 340 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

332 FLUID THERAPY

moderate volume expansion. Fluid administration is TABLE 14-1 Daily Water and Calorie
contraindicated in patients with predominantly cardio- Requirements for the
genic forms of shock.
Regardless of their underlying disease, severely Dog*
dehydrated patients can be in shock and require a resus- Body Total kcal/day
citation phase of fluid therapy before initiating the rehy- Weight (kg) or Water mL/day /kg /hr
dration phase. However, not all patients in shock are
dehydrated and thus may or may not require a rehydra- 1 132 132 6
tion phase of therapy. The rapidity and volume of loss 2 214 107 9
from both the intravascular and extravascular fluid 3 285 95 12
compartments in conjunction with the extent of any com- 4 348 87 15
pensatory response will determine whether the patient is 5 407 81 17
in shock or is dehydrated. 6 463 77 19
7 515 74 21
IS THE PATIENT 8 566 71 24
9
615
26
68
DEHYDRATED? 10 662 66 28
11 707 64 29
The need for a rehydration phase is dependent on the 12 752 63 31
underlying condition of the patient. For surgical patients, 13 795 61 33
there are additional indications for fluid therapy, such as 14 837 60 35
maintenance of venous access for emergencies and estab- 15 879 59 37
lishment of diuresis to maintain renal perfusion during 16 919 57 38
anesthesia (see Chapter 17). For medical patients, the 17 959 56 40
answer to this question depends on an assessment of 18 998 55 42
the animal’s state of hydration. The hydration status of 19 1037 55 43
20 1075 54 45
the animal is estimated by careful evaluation of the
21 1112 53 46
history, physical examination findings, and the results 22 1149 52 48
of a few simple laboratory tests. 7,11
23 1185 52 49
In its most narrow sense, dehydration refers to loss of 24 1221 51 51
pure water. However, the term dehydration usually is 25 1256 50 52
used to include hypotonic, isotonic, and hypertonic fluid 26 1291 50 54
losses. The type of dehydration is classified by the tonicity 27 1326 49 55
of the fluid remaining in the body (e.g., a hypotonic loss 28 1360 49 57
would result in hypertonic dehydration). Isotonic and 29 1394 48 58
hypotonic losses are most common in small animal prac- 30 1427 48 59
35 1590 45 66
tice. Isotonic fluid loss can result in volume depletion and
40 1746 44 73
nonosmotic stimulation of antidiuretic hormone (ADH)
45 1896 42 79
release, thus preventing effective excretion of consumed
50 2041 41 85
water and resulting in hypotonic dehydration. Types of 55 2182 40 91
dehydration are depicted in Figure 3-1 and are discussed 60 2319 39 97
in detail in Chapter 3. 70 2583 37 108
80 2836 35 118
FLUID BALANCE 90 3080 34 128
Normal sources of fluid input are water consumed in 100 3316 33 138
food, water that is drunk, and water produced in the body
as a result of metabolism. Nutrient oxidation produces From Haskins SC. A simple fluid therapy planning guide. Semin Vet Med
Surg (Small Anim) 1988;3:232.
approximately 0.1 g of water per kilocalorie of energy *132 kcal/kg 0.75 ; Nutritional requirements of the dog. Bethesda, Md:
released. 2 Maintenance water and electrolyte needs National Research Council, 1985.
parallel caloric expenditure, 20,22,23 and normal daily
losses of water and electrolytes include respiratory, fecal, Normally, cutaneous losses are unimportant in dogs
and urinary losses. Estimated daily caloric and water and cats because eccrine sweat glands are limited to the
requirements for dogs and cats are shown in foot pads and do not play an important role in thermo-
Tables 14-1 and 14-2 23 and in Figure 14-1. 20 Respiratory regulation in these species. Sympathetic stimulation as a
loss of fluid can be important in dogs because panting has result of heat stress in the cat may result in increased secre-
been adapted for thermoregulation in this species. tion of saliva, and a small volume of fluid may be lost by
Pyrexic patients also can lose fluid by this route. this route.