Page 397 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Monitoring Fluid Therapy and Complications of Fluid Therapy 387

TABLE 16-1 Physical Signs TABLE 16-3 Physical Findings
Associated with Associated with
Dehydration Inadequate Tissue
Perfusion
Percent
Dehydration Physical Signs Assessment Confounding Factors

<5 Not detectable Mucous Membranes
5-6 Mild loss of skin elasticity Pale pink Vasoconstriction caused by pain or
6-8 Definite loss of skin elasticity anxiety
May have dry mucous membranes Anemia
May have depressed globes within orbits Pale Volume loss overestimated because
8-10 Persistent skin tent with slow return because of vasoconstriction caused by
of loss of skin elasticity pain or anxiety
10-12 Persistent skin tent because of loss of skin Dark pink or red Vasodilatation and may be
Elasticity interpreted as normal volume
Depressed globes within orbits Hemoconcentration may be
Dry mucous membranes interpreted as normal volume
Signs of perfusion deficits (CRT >2 sec,
Capillary Refill Time
tachycardia)
12-15 Signs of shock <1 sec may be considered adequate
Death perfusion
Difficult to interpret if peripherally
vasoconstricted because of pain
Note: The association between % dehydration and circulatory compromise
must also be considered with rate of fluid loss. Chronic fluid loss may result or anxiety
in severe dehydration, but perfusion may be adequate; however, fluid loss
occurring acutely will result in circulatory collapse at an estimated lower
level of hydration. Therefore perfusion status cannot consistently be used to findings. We derive our therapeutic plan using mathemat-
assess hydration status. ical formulas based on an estimated percentage of intra-
CRT, capillary refill time.
vascular or tissue loss. Our assessment may not be
accurate, and therefore the volume of fluid given should
be titrated to the patient’s needs and the physiologic
TABLE 16-2 Confounding Factors of responses to the fluid administered. The extent and inva-
Physical Findings siveness of monitoring used to assess these responses are
Associated with dependent on the severity of illness and stability of the
patient, other therapies administered, the interrelation-
Dehydration
ship among variables affecting the hemodynamic profile
Assessment Confounding Factors (e.g., anemia and perfusion, CVP and mechanical venti-
lation), the availability of various monitoring devices,
Skin turgor (“tent”) Young animals with subcutaneous fat and the level of expertise of the clinician and support staff.
Obese animals with subcutaneous fat This latter point is very important because interpretation
Cachectic animals of an isolated result, especially when monitoring devices
Geriatric animals with loss of tissue are not frequently used, can complicate treatment
elasticity regimens.
Mucous membranes
Dry Panting, tachypnea, dyspnea ENDPOINTS OF FLUID
Moist Nauseated, vomiting, drinking RESUSCITATION
Position of the globe Cachexia
Perfusion status Affected by rate of fluid loss; chronic During administration of any fluid, basic monitoring
loss may not affect perfusion techniques should be performed, including heart rate
parameters until a large volume is lost (HR), respiratory rate (RR), pulse pressure, capillary refill
time (CRT), mucous membrane (MM) color, mentation,
and temperature and color of the distal limbs and digits.
MONITORING Although abnormalities in these parameters may not be
sensitive indicators of hypovolemia, 60 a general goal for
Assessment of the volume of fluid required to correct endpoints of resuscitation should be values within the
fluid deficits in all compartments cannot be accurately normal range for the size and species of animal with
derived. Therefore our therapy always is empirical and recovery to normal mentation and warm, pink digits.
based on history, physical examination, and laboratory Monitoring urine production with a goal of 0.5 to