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35 Approach to the Patient in the Critical Care Setting 349

Prior to referral of critically ill patients, the treating cli- transducer) and indirect (Doppler and sphygmoma-
VetBooks.ir nician should call the intended receiving facility and nometer or oscilllometric measurements) options. A
good general goal is to maintain a mean arterial blood
speak to the specialist who will be taking control of the
case to ensure the transfer is made as safe and efficient as
>90 mmHg for optimal organ and tissue perfusion.
possible. All available medical records should be copied pressure >60 mmHg and a systolic blood pressure
and should accompany the pet in a hard copy format. Hypotension that is nonresponsive to fluid therapy
may indicate the presence of an underlying acid–base
or electrolyte disorder or the need to begin therapy
The “Rule of 20” with a vasoactive agent. Central venous pressure and
lactate monitoring can provide additional information
In addition to serial physical exams and frequent reeval- on the need for vasopressor therapy. While less com-
uation of the active problem list, there are a multitude of monly encountered clinically, monitoring for and
critical parameters that need to be evaluated at least treatment of hypertension are useful to prevent com-
daily in the critical patient. Developed by Rebecca Kirby, plications including retinal detachment, neurologic
a founding Diplomate of the American College of impairment, and end‐organ injury.
Veterinary Emergency and Critical Care, the “Rule of 20”
provides a comprehensive tool to guide the continuous Cardiac Function
evaluation and integration of a patient’s organ systems,
laboratory findings and treatment and many critical care Heart function should be evaluated not only by heart rate
specialists find it useful to refer to the “Rule of 20” on a and rhythm but also ability to effectively pump blood
daily basis with critically ill patients. Each element will forward through evaluation of peripheral limb tempera-
be discussed below, many of which will be covered in tures and capillary refill time. Electrocardiographically
detail in other chapters. confirmed arrhythmias should be treated if perfusion is
compromised. Echocardiography is helpful in identifying
underlying structural heart disease as well as visualizing
Fluid Balance cardiac filling and contractility. Additional treatments
Fluid therapy is a common treatment in critical patients directed at optimizing cardiac function, including IV
with a goal to reestablish and maintain hydration and to fluids, inotropic support or afterload reduction, should
ensure circulating volume is maintained. Often dehydra- be introduced as indicated.
tion and hypovolemia require rapid fluid replacement in
the form of boluses. After initial volume expansion and Albumin
rehydration, each patient’s “maintenance” fluid needs
will differ due to underlying conditions, ongoing losses, Albumin is a blood protein produced by the liver that
and variations in metabolism. Each patient will also have plays an essential role in a multitude of physiologic
a unique ability to tolerate administered fluids. The con- processes, including fluid balance, drug transport, tis-
sequences of overhydration or inappropriate fluid redis- sue healing, and coagulation. Synthetic colloids can be
tribution include pulmonary edema, peripheral edema, used to maintain fluid in the intravascular space but
and third spacing of fluids within body cavities. they do not substitute for albumin’s other roles in the
Assessment of response to administered fluids requires body and may be associated with acute kidney injury.
monitoring of many parameters, including mucous Albumin levels <2 g/dL have been associated with a
membrane color and moistness, skin turgor, heart rate, poor prognosis in critically ill patients and may indi-
and body weight. Each of these parameters should be cate the need for replacement with plasma (frozen or
assessed several times per day. Monitoring of blood fresh frozen) or canine albumin transfusions.
pressure and urine output can provide additional infor-
mation on a patient’s needs. Monitoring of central
venous pressures and changes in blood gas variables Oncotic Pull
(lactate, base deficit) are used for advanced monitoring Adequate oncotic pressure is required to maintain
of fluid therapy. appropriate intravascular volume and prevent inter-
stitial fluid loss that can propagate hypovolemia and
Blood Pressure and Perfusion edema formation. Oncotic pressure changes in direct
correlation with albumin concentration and can there-
There are many methods to monitor blood pressure, fore be augmented with administration of natural
including direct (via an arterial catheter and pressure colloids.