Page 355 - Feline Cardiology

370 Section L: Comorbidities

accepting of the importance of monitoring for signs of Specific management strategies for acute decompen-
congestive heart failure should the patient’s threshold for sation of cardiac or renal disease in a patient with dis-
intravascular volume expansion be exceeded; and both orders of both systems include the following (see also
the owner and the cat are tolerant of the treatments. Table 24.1):
Although 75–100 ml/cat can typically be administered q
24–72 hours (Polzin 2010) in cats that have chronic • Identify and address reversible causes (CHF: e.g.,
kidney disease but normal hearts, a more conservative recent sodium-rich dietary indiscretion, glucocorti-
volume is typically chosen when heart disease is present coid administration; uremia: e.g., pyelonephritis).
concurrently. For example, 50–75 ml can be administered Occasionally in cats with acute congestive heart failure,
q 24–48h if azotemia is substantial (e.g., serum creatinine the underlying cardiac lesion is noted to be minimally
>2.5 mg/dl [220 umol/l]), or q 48–72h if azotemia is less worse, if at all, compared to the previous evaluation,
severe. With IRIS stage 3 (serum creatinine = 2.9 − 5 mg/ especially echocardiographically. In such instances it
dl [255–440 umol/l], clinical signs usually present) and is important to ask the owner about the possibility of
stage 4 (serum creatinine >5 mg/dl [>440 umol/l], clini- acute precipitating factors such as acute salt ingestion,
cal signs essentially always present), subcutaneous fluid a stressful tachycardic event such as inter-cat conflict
therapy administered at home may produce clinical or being chased, or recent repositol corticosteroid
improvements that are more substantial. Therefore, the administration. Inquiring whether a treat was given by
benefit-to-risk ratio in such cases tilts further toward a relative or friend, a food scrap or other indiscretion
home fluid therapy. Such cats should not be receiving was found by the cat, or an extra meal was given by a
diuretics for heart disease, or if they are, the diuretic or neighbor, may identify a basis for a sudden but tran-
the parenteral fluid administration should be discontin- sient increase in intravascular volume due to ingestion
ued (depending on whether the kidney or heart disorder of greater-than-normal quantities of sodium. Failure
is producing the most severe clinical signs, respectively) to investigate this aspect of the patient’s history leads
and the other treatment decreased accordingly, because to the conclusion that heart failure was caused by
diuretics and parenteral fluids are mutually antagonistic worsening of the disease, and the clinician’s response
(see below). With advanced kidney disease patients, the likely is to prescribe a higher dosage of diuretics indef-
administration of subcutaneous fluids is a palliative initely, rather than for only 48–72 hours to offset the
measure that is undertaken only when signs of overt sodium/fluid excess caused by the dietary indiscre-
illness are present and is pursued only if an appreciable tion. Doing so would clearly not be in a cat’s interest
improvement in the cat’s quality of life is noted by owners if he/she has concurrent renal disease. The worsened
prognosis conveyed in this context is also not justified
as a result. In all cases, it is essential to discuss the diver-
Comorbidities gence of renal and cardiac pathophysiology, and signs of • With uremia, identifying acute-on-chronic processes
when heart failure was a temporary, sodium ingestion-
related aberration.
decompensation of either one, with the owner and to
obtain owner consent for instituting such treatment.
Chronic versus Acute Decompensation such as low-grade pyelonephritis is important.
Pyelonephritis can produce few or no overt clinical
Patients who present in an acute crisis (congestive signs and may not produce an active urine sediment;
heart failure or acute renal failure) may require in- urine culture is warranted periodically (e.g., q 4–12
hospital treatment for days, and the magnitude of months) in cats with chronic kidney disease
treatment is substantially different than that of outpa- because identifying a bacterial infection offers the
tient treatment once the patient is discharged. This possibility of successful treatment and improvement
important distinction means, for example, that much in renal function. The alternative, if pyelonephritis
higher dosages of diuretics may be used in-hospital is missed, can be deteriorating renal function and
for 1 or 2 days, despite azotemia, if such dosages allow the need for additional therapies such as parenteral
the patient to survive and recover rapidly from conges- fluids, which would preferably be avoided if possible
tive heart failure. Similarly, a cardiac patient with acute in any cat, particularly one with concurrent heart
worsening of chronic kidney disease may benefit from a disease.
short (24–48 hours) discontinuation of diuretics and/or • Assess patient for onset of gallop heart sound during
a course of intravenous fluid therapy to restore hydration fluid therapy, suggesting iatrogenic CHF. Use IV fluid
and in turn improve demeanor and appetite, even though type that matches needs (e.g., no replacement fluids
such treatment would not be continued long-term. The like lactated Ringer’s solution/0.9% NaCl when
use of these strategies requires ongoing monitoring to patient is euvolemic [well-hydrated], but rather use
identify early signs of decompensation (overshooting) maintenance fluids such as 0.45% NaCl in 2.5%
and identification of concurrent or complicating factors. dextrose). The importance of these concepts is