Small Animal Fluid Therapy, Acid-base and Electrolyte Disorders: A Color Handbook

192 Pages·2013·5.6 MB·English

by  Elisa M Mazzaferro

A Color Handbook
Small Animal Fluid,
Electrolyte and
Acid-base
Disorders
Elisa Mazzaferro,
MS, DVM, PhD,DACVECC
Cornell University Veterinary Specialists
Stamford, CT, USA
MANSON
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ISBN: 978-1-84076-167-2
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CONTENTS
3
Preface . . . . . . . . . . . . . . . .4 CHAPTER 3 CHAPTER 7
Abbreviations . . . . . . . . . . .5 Components of Parenteral nutrition
crystalloid fluids and
Introduction . . . . . . . . . . .120
potential complications
CHAPTER 1 of fluid therapy Parenteral nutrition . . . . . .122
Fluid compartments and Complications of parenteral
total body water Introduction . . . . . . . . . . . .48 nutrition . . . . . . . . . . .129
Constituents of crystalloid
Introduction . . . . . . . . . . . . .8 Conclusions . . . . . . . . . . .130
fluids . . . . . . . . . . . . . . .52
Fluid compartments and
Complications of intravenous
total body water . . . . . . . .8
fluid therapy . . . . . . . . . .57 CHAPTER 8
Fluid exchange between Shock: recognition,
compartments . . . . . . . . .9
pathophysiology,
CHAPTER 4
Osmolality . . . . . . . . . . . . .10 monitoring, and
Colloids
Dehydration versus treatment
hypovolemia . . . . . . . . . .11 Introduction . . . . . . . . . . . .66
Introduction . . . . . . . . . . .132
Response to hypovolemia . .12 Colloid characteristics . . . . .66
Hypovolemic shock . . . . . .132
Maintenance fluid Colloids . . . . . . . . . . . . . . .72
Cardiogenic shock . . . . . .138
requirements . . . . . . . . .14
Distributive shock . . . . . . .142
Sensible and insensible CHAPTER 5
fluid losses . . . . . . . . . . .16 Obstructive shock . . . . . . .144
Canine and feline blood
Fluid balance . . . . . . . . . . .16 banking and blood Care and ‘Rule of
Twenty’ . . . . . . . . . . . .145
Measurements of product administration
‘ins and outs’ . . . . . . . . .18
Introduction . . . . . . . . . . . .80
Rehydration . . . . . . . . . . . .19 CHAPTER 9
Economics of blood
Conclusions . . . . . . . . . . . .19 banking . . . . . . . . . . . . .80 Case examples for
fluid therapy
Selection of donors . . . . . . .81
CHAPTER 2 Case 1: Gunther . . . . . . . .152
Blood typing . . . . . . . . . . . .82
Techniques and Case 2: Casey . . . . . . . . . .154
Cross-match procedure . . . .86
complications of Case 3: Zeke . . . . . . . . . . .159
vascular access Blood collection . . . . . . . . .88
Case 4: Buster . . . . . . . . . .162
Blood components . . . . . . .90
Introduction . . . . . . . . . . . .22 Case 5: Lolita . . . . . . . . . .164
Transfusion therapy . . . . . . .97
Types of intravenous Case 6: Lucky . . . . . . . . . .166
catheters . . . . . . . . . . . .22
Case 7: Mango . . . . . . . . .169
Peripheral venous CHAPTER 6
Case 8: Jake . . . . . . . . . . .171
catheters . . . . . . . . . . . .27 Diagnosis and treatment
Central venous catheters . . .33 of electrolyte Case 9: Rocket . . . . . . . . .174
abnormalities
Intraosseous catheterization .38
Arterial catheterization . . . .40 Disorders of sodium . . . . .104 References . . . . . . . . .177
Vascular cutdown . . . . . . . .42 Disorders of chloride . . . . .108
Index . . . . . . . . . . . . .185
The three-syringe blood Disorders of potassium . . .110
sampling technique . . . .44 Disorders of calcium . . . . .113
Maintenance of the Disorders of phosphorus . .115
intravenous catheter . . . .44
Disorders of magnesium . .117
Complications associated
with intravenous
catheterization . . . . . . . .44
PREFACE
4
Fluid therapy is one of the most important well as potential complications of intravenous
aspects of therapy in both small and large catheterization. Next, the various types of crys-
animal medicine. It is also extremely contro- talloid and colloid fluids and how they behave
versial, in that there are many opinions as to within the body are described. Transfusion
how to provide fluid therapy in different medicine and electrolyte disorders are
disease states. The descriptions provided within discussed in the next two chapters, followed by
this text are meant to be used as guidelines that discussion of various forms of shock, resuscita-
this author follows when implementing fluid tion, and monitoring during shock states. The
and transfusion therapy. The text is divided into final chapter then describes clinical cases in
chapters that describe the physiologic fluid which the concepts described in the text can be
compartments within the body and how fluid applied in daily practice. It is my hope that the
travels from place to place within the body. The readers will find this text useful when treating
next chapter describes how to place and main- their own patients.
tain intravenous and intraosseous catheters, as
ABBREVIATIONS
5
ACD acid–citrate–dextrose FIV feline immunodeficiency virus
ACT activated clotting time FP frozen plasma
ACTH adrenocorticotropic hormone GI gastrointestinal
ADH antidiuretic hormone HBOC hemoglobin-based oxygen carrier
ADP adenosine diphosphate ICP intracranial pressure
APTT activated partial thromboplastin IFA immunofluorescent assay
time MAP mean arterial pressure
ATP adenosine triphosphate MODS multiple organ dysfunction
COP colloid osmotic pressure syndrome
CPDA citrate–phosphate– PCR polymerase chain reaction
dextrose–adenine PCV packed cell volume
CPP cerebral perfusion pressure PN parenteral nutrition
CRI constant-rate infusion PPN partial parenteral nutrition
CRT capillary refill time pRBC packed red blood cell
CSF cerebrospinal fluid PT prothrombin time
CVP central venous pressure PTH parathyroid hormone
D5W 5% dextrose in water REE resting energy expenditure
DEA dog erythrocyte antigen RSAT rapid slide agglutination test
DIC disseminated intravascular SIADH syndrome of inappropriate ADH
coagulation secretion
DKA diabetic ketoacidosis SIRS systemic inflammatory response
DOCP desoxycorticosterone pivalate syndrome
ECG electrocardiogram TAT tube agglutination test
ELISA enzyme-linked immunoabsorbent TBW total body water
assay TPN total parenteral nutrition
FDP fibrin degradation product TS total solids
FeLV feline leukemia virus VAP vascular access port
FFP fresh frozen plasma VWf von Willebrand factor
FIP feline infectious peritonitis
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CHAPTER 1
7
Fluid
compartments and
total body water
• Introduction
• Fluid compartments and total body water
• Fluid exchange between compartments
• Osmolality
• Dehydration versus hypovolemia
• Response to hypovolemia
• Maintenance fluid requirements
• Sensible and insensible fluid losses
• Fluid balance
• Measurement of ‘ins and outs’
• Rehydration
• Conclusions
8 CHAPTER 1 Fluid compartments and total body water
INTRODUCTION Intracellular fluid is located within cells, and
contributes approximately two-thirds (66%) to
total body water. Extracellular fluid is that
In small animal medicine, it is now considered which is located outside of cells, and
to be the standard of care to administer contributes approximately one-third (33%) to
intravenous fluids to any patient that has a total body water. Extracellular fluid can be
condition that is associated with a lack of fluid further subdivided into the intravascular and
intake or with fluid loss. Some persons may interstitial compartments. The intravascular
think that the science and thought processes space contains fluid that is contained within
behind fluid administration are mysterious and blood vessels. It is through these vessels that
complex. However, fluid therapy can be plasma water, cellular components, proteins,
simplified a little by first providing information and various electrolytes flow. The interstitial
about fluid composition and compartments extravascular compartment is the space located
within the body, describing how fluid moves outside of the blood vessels. Of this,
from compartment to compartment, and how intravascular fluid contributes only 8–10% of
to recognize and treat fluid derangements, TBW, whereas interstitial fluid contributes 24%
including hypovolemia and various degrees of of TBW. A very small amount of fluid is known
dehydration. as transcellular fluid, and is located within the
gastrointestinal tract, joints, cartilage, and
cerebrospinal space.1 It has been estimated
FLUID COMPARTMENTS AND that total body water is approximately
TOTAL BODY WATER 534–660 mL/kg in a healthy dog.1 Total
intravascular fluid volume has been estimated
as 80–90mL/kg in dogs and cats. Of that, the
Water is essential for life. Without water, normal fluid component, or intravascular plasma
body functioning is impaired, and ultimately water volume, has been estimated to be
this can lead to death if therapeutic approximately 50 mL/kg in dogs, and
interventions are not implemented. A 45mL/kg in cats.1
discussion of intravenous fluid administration
would be incomplete without an understanding
of total body water (TBW) and fluid balance
between the various compartments within the
body.
Water is a major contributor to an animal’s
1
body weight. An understanding of electrolyte
and protein composition within the body is
r
essential to help maintain homeostasis and to ula Interstitial (23%)
use the variety of fluids that are available to %ell
3c
treat specific abnormalities. Approximately 60% 3a
of a healthy animal’s total body weight is water. xtr Intravascular (10%)
e
This value can change slightly depending on
age, lean body mass, degree of leanness or
obesity, and gender. For example, neonatal
r
a
puppies and kittens have a relatively higher ul
pAedricpeonstea gteis souf ew caotenrt ainin tsh meior rbeo wdiaetse trh tahna nad duoltess. 66%acell Intracellular (66%)
r
muscle, and can contribute to a larger nt
i
percentage of water in obese animals.
Water is located in separate yet intertwined
compartments within the body. Conceptually,
the body can be divided into the intracellular
and extracellular compartments (1). 1 Diagram of body water compartments.
Fluid exchange between compartments 9
FLUID EXCHANGE BETWEEN where kf=the filtration coefficient (varies from
COMPARTMENTS tissue to tissue within the body); P and P is
c i
the hydrostatic pressure within the capillary
(P) and interstitial space (P), σis the pore size
c i
Total body water is in a constant state of flux of the capillary membrane and πdescribes the
between the various compartments within the colloid effect of protein, such as albumin, in
body. The rate of fluid exchange largely the capillary (π) and the interstitium (π).
c i
depends on the forces that favor fluid retention Finally, Q describes the rate of lymph flow
lymph
within a compartment versus the forces that from the interstitium.2
favor fluid movement or filtration from a When hydrostatic forces exceed colloid
compartment. The colloid osmotic pressure osmotic forces, fluid will leave one
(COP) of a compartment is dictated by the compartment and go to the other (2).
concentration of protein within that space. Conversely, a relative increase in colloid
Albumin is a protein which contributes osmotic forces within a compartment can
approximately 80% to COP. Hydrostatic retain fluid within, or draw fluid into, the
pressure is the pressure generated by the compartment. Flow of fluid from a
force of fluid within a compartment. The compartment will increase the colloid osmotic
COP influences fluid retention within a pressure of that compartment, and then will
compartment, while the hydrostatic pressure increase the hydrostatic pressure of the
influences fluid movement from the compartment into which it moves. A more
compartment. detailed explanation of a protein’s effect on
Starling’s equation predicts fluid flux fluid flux within the body will be given in
between compartments in the body (2).2The Chapter 4.
equation is as follows:
V=[kf (P −P) −σ(π −π )] − Q
c i c if lymph
2 Diagram to
2
illustrate Starling’s
Cells in tissue equation of fluid
fluxbetween
compartments in the
body.P:hydrostatic
c
∏ pressure within
P ∏c Interstitial fluid c Pi thecapillary;
i
P:hydrostatic
i
pressure within the
P P
c ∏i Vessel ∏i c iπn:ttehres tcitoialllo sipda ecfefe;ct
ofprotein,such as
albumin,in the
capillary (π) and the
c
Filtration out Absorption in interstitium (π).2
i