Page 290 - Problem-Based Feline Medicine

282 PART 5 CAT WITH ACUTE ILLNESS

● Moderate hyperkalemia (6.5–8.0 mEq/L) should
it is best used in conjunction with insulin to min-
always be treated promptly.
imize exacerbation of hyperosmolality.
● Severe hyperkalemia (> 8.0 mEq/L) may be life-
– Enhance potassium secretion. Give furosemide
threatening and usually requires aggressive treat-
as discussed below. This may be used in the
ment. The higher the potassium level and the worse
management of mild hyperkalemia, or subse-
the clinical signs, the more rapid and aggressive
quent to emergency management of moderate to
should be the treatment. Treatments include:
severe hyperkalemia, but it will not act rapidly
– Dilution of potassium concentration by rapid
enough to correct hyperkalemia that is causing
infusion of intravenous fluids (60 ml/kg/h).
clinical signs, especially in the presence of olig-
Potassium-free solutions have the most dilu-
uria or anuria where the drug may not promote
tional effect. Saline is beneficial for this reason
urine production.
although it is acidifying. Note that life-threaten-
ing hyperkalemia in acute renal failure is most Diuretics.
likely to occur in anuric animals, which may not – If anuria or oliguria persists after fluid
tolerate a large fluid bolus. replacement, administer furosemide 2 mg/kg.
– Protect the heart against the membrane effects If diuresis does not occur within 30 minutes,
of hyperkalemia with 10% calcium gluconate, repeat once. Furosemide will not improve
0.5–1.0 ml/kg IV, over 5–15 minutes. This glomerular filtration rate, but diuresis may
should be given if there is a life-threatening reduce tubular blockage and tubular back-
arrhythmia. Monitor the ECG during therapy. leak, and a polyuric animal is easier to manage
– Translocate potassium from the blood into the than an oliguric one. If diuresis does occur, treat-
intracellular fluid. Usually only one of the fol- ment may be given two to three times a day if
lowing treatments is necessary. needed to maintain diuresis. Fluid requirements
– NaHCO , 0.5 mEq/kg IV over 5 minutes, fol- will be increased. Constant-rate infusions of
3
lowed by another 0.5 mEq/kg over the next furosemide have been used in the management
30–60 minutes. This treatment is best reserved of acute renal failure in dogs but there is limited
−
for cats with HCO or total CO < 12 mmol/L, experience with cats. Constant rate infusions of
3 2
if measurements are available. furosemide at 0.25 mg/kg/h have been used in
– Dextrose: Severe hyperkalemia or moderate the management of congestive heart failure in
hyperkalemia with clinical signs – give 50% dex- cats and may be considered in the management
trose, 1.0–2.0 ml/kg IV (ideally diluted 1:1 with of acute renal failure.
sterile water or saline), over 30–60 minutes. ● Osmotic diuretics.
Moderate hyperkalemia without clinical signs – – If furosemide fails to induce a diuresis, con-
add 5–10% dextrose to the fluids (100–200 ml sider using 10–20% dextrose as an osmotic
50% dextrose/L). Monitor blood glucose. Note diuretic, 25–50 ml/kg over 1–2 hours. Monitor
that dextrose may also serve as a diuretic. urine for glucosuria indicating adequate dosage.
– Insulin-dextrose: regular insulin 0.1–0.5 units/kg Diuresis should occur within 60 minutes of com-
IV followed by 2–4 ml of 50% dextrose/unit of pleting infusion. If diuresis results, the treatment
insulin given (ideally diluted 1:1 with sterile may be repeated every 8–12 hours.
water or saline) and then followed by adding – Mannitol may also be used as an osmotic
2.5% dextrose to the fluids (50 ml of 50% dex- diuretic at a dose of 0.25–0.5 g/kg over 10 min-
trose/L of fluids). Monitor blood glucose. Note utes. Diuresis should occur within 60 minutes of
that NaHCO and dextrose should be avoided if completing infusion. If diuresis results, the treat-
3
effective serum osmolality is > 330 mOsm/kg. ment may be repeated every 4–6 hours. Mannitol
(Effective osmolality is calculated as [1.86(Na + is a more potent osmotic agent than dextrose, but
+
+
K )] + glucose + 9, with all units in mmol/L.) If can only be eliminated by renal excretion, and
the cat is hyperosmolar and dehydrated, increase carries a higher risk of causing pulmonary
the fluid rate. If dextrose therapy is needed, then edema.