Page 395 - Clinical Small Animal Internal Medicine

36 Fluid Therapy 363

Albumin Replacement Constant Rate Infusions
VetBooks.ir In critically ill veterinary patients, it may become neces- In addition to their uses in volume expansion and the

correction of dehydration, intravenous fluids are often
sary to address albumin deficiency due to ongoing
albumin loss (e.g., protein‐losing nephropathy, septic used as carriers for drugs that are best administered by
peritonitis) or decreased albumin production (e.g., acute constant rate infusion (CRI). Examples include vasopres-
phase response, liver failure). The majority of total body sors, some inotropes, and some vasodilators. Also, CRIs
albumin actually resides within the interstitial space so for the administration of anesthetics and analgesics are
correction of an albumin deficit can be difficult to commonplace. Before starting a CRI, the compatibility of
achieve using albumin‐containing products such as fresh the drug and carrier fluid must be determined. In most
frozen plasma. Existing interstitial albumin deficits must instances, 0.9% NaCl or 5% dextrose in water are accept-
be replaced before improvement of plasma albumin con- able choices.
centrations will be seen. Constant rate infusions are dosed based on both
Albumin concentrate is administered as either a 5% weight and time. For example, a CRI of dopamine might
solution or a 25% solution. The 5% solution of human be started at a dose of 5 μg/kg/min. This dose of drug is
serum albumin (HSA) has a COP of about 20 mmHg and then administered in a specific volume of fluid. The vol-
an albumin concentration approximately equal to plasma ume of fluid administered is determined based on the
while the 25% solution has a much higher COP of about patient’s body weight and fluid status, and the concentra-
70 mmHg and an albumin concentration five times that tion of drug that requires delivery. To calculate a CRI, the
of plasma. In veterinary medicine, both 5% and 25% HSA following information must be known.
have been administered for albumin replacement in Patient weight (kg).
both dogs and cats. Studies have shown both acute and ● Drug dose (5 μg/kg/min, for example).
delayed hypersensitivity reactions in dogs. The incidence ● Starting rate of fluid administration (5 mL/h, for
of these reactions appears lower in critically ill patients ● example).
but the studies that have investigated the use of these Concentration of the drug administered.
solutions have been limited. In patients with significant ● Total volume of carrier fluid to be supplemented.
albumin deficits, the volume of plasma that would need ●
to be administered to effect change in serum albumin To be precise, when formulating a CRI, an equivalent
often precludes its use as an effective therapy. For this volume of carrier fluid should be removed and replaced
reason, concentrated albumin products such as 25% by the drug being delivered. For examples of CRI formu-
HSA or canine lyophilized albumin (a canine albumin lation, the reader is referred to supplemental materials
product has been introduced to the US market but little available online.
has yet been published regarding its use) are more effec-
tive in correcting albumin deficits. When correcting
albumin, the following equation can be employed: Monitoring of Fluid Therapy

Albumin deficit grams 10 One of the great challenges of fluid therapy is to meet the
[ desired albuming/dL patient allbumin g/dL ] patient’s ongoing requirements and replace deficits with-
body weight kg . 03 out overloading the body’s ability to cope with the
volume. An understanding of the behavior of fluids
within the body as well as body fluid compartment
As an example, to increase the albumin in a 10 kg dog dynamics helps to avoid complications. When attempt-
from 1.5 to 2.0 g/dL:
ing to assess the adequacy of fluid therapy, various
parameters can be monitored.
.
Albumin deficit 10 20 15 10 03 15 grams Perfusion parameters such as heart rate, respiratory
.
.
rate, capillary refill time, and pulse quality are valuable in
Assuming an albumin concentration of 5 g/dL of canine determining the need for rapid volume expansion but
plasma, this patient would require approximately 300 mL they do not provide information regarding the correc-
of plasma (identical volume to 5% HSA). By contrast, this tion of dehydration. Perfusion parameters can be normal
patient would require 60 mL of 25% HSA. Given the cur- in the dehydrated animal, although the profoundly dehy-
rent costs of HSA versus canine plasma, this could result drated animal will exhibit signs of hypovolemia.
in a significant saving to the client. The recommended Patients should be weighed at least once daily to track
dose for the lyophilized canine albumin product has alterations in fluid balance, keeping in mind that 1 L of
been reported to be 800–884 mg/kg IV. water is effectively equivalent to 1 kg of weight. The