Patient preparation

1Copyright © 2011, 2003, 2000, 1994 by Mosby, Inc., an affiliate of Elsevier Inc.
Patient Preparation
All successful anesthetic procedures begin with
careful patient preparation.
Chapter 2

Role of the Veterinary Anesthetist
 Minimum patient database
 Proper patient fasting
 Preinduction patient care
 All supplies are available
 All equipment is in working order
 Preanesthetic medication

Communication is Important
 Makes clients feel more comfortable and less
anxious
 Clients are more confident in your work
 Good communication shows you care
 An informed client can better handle
unexpected results

Clients don’t care how much you
know, until they know how much you
care.

Minimum Patient Database (MPD)
 Patient history
 Physical examination and assessment
 Preanesthetic diagnostic workup

Confirm the Scheduled Procedure
 Verbally
 Prevents tragic accidents
 Anesthetizing the wrong patient
 Performing an unnecessary procedure
 Not performing a scheduled procedure

Confirm the Scheduled Procedure
(Cont’d)
 Know the specifics
 Exact location of tumors
 Exact location
 Owner’s wishes regarding cytology or histology
 Owner’s wishes regarding decisions during the
procedure

Patient History
 Information obtained from the client
 Know what questions to ask and how to ask
them
 Yes-no questions
 Leading questions

Patient History (Cont’d)
 In addition to information given freely,
determine the following:
 Information given freely
 Duration
 Severity or volume
 Frequency
 Appearance or character

Patient History—Signalment
 Species
 Species have unique responses to anesthetic
agents
 Horses and cats—opioids
 Dosing requirements
 Recovery—horses
 Anticholinergics avoided in ruminants
 Ventilation support—large animals
 Excess airway secretions—cats and ruminants
 Exotic animals are handled differently

Patient History—Signalment (Cont’d)
 Breed
 Differences in anatomy and physiology
 Sighthounds—sensitive to barbiturates
 Boxers and giant breeds—sensitive to
acepromazine
 Terriers—resistant to acepromazine
 Brachiocephalic dogs—difficult to intubate
 Draft horses—sensitive to sedatives

 Age
 Plays a factor in drug choice
• Neonates and pediatric patients
• Geriatric patients

 Sex and reproductive status
 Male or female
 Intact or neutered
 Used for breeding?
 Pregnant
 Stallions—acepromazine
 Pregnant cows and ewes—xylazine

Patient History—Medications
 Current or past
 May influence effect of anesthetic agents
 Sympathomimetics
 Tricyclic antidepressants
 Antibiotics
 Monoamine oxidase inhibitors
 Antihistamines

Patient History—Allergies/Drug
Reactions
 Record in the history to prevent future
administration
 Past adverse reactions to anesthetic agents
 Cats—prolonged ketamine recovery
 Dogs—behavioral change after acepromazine
sedation

Patient History—Preventive Care
 Vaccination—date and type
 Fecal analysis and parasite control
 Heartworm status—dogs
 FLV and FIV testing—cats
 Tetanus toxoid—horses

Patient History—Past/Current
Illnesses
 Preexisting disease
 Anorexia, vomiting, diarrhea, coughing,
sneezing, polyuria, polydipsia, tenesmus,
dysuria
 General signs of illness
 Stabilized prior to anesthesia
 Change in behavior
 CNS disorder
 Pain
 Systemic illness

Patient History—Past/Current Illnesses
(Cont’d)
 Exercise intolerance
 Heart disease
 Anemia
 Musculoskeletal pain
 Weakness
 A nonspecific sign
 Fainting or seizures
 Often difficult to differentiate
 Have different etiologies

Past History—Past/Current Illnesses
 Unexplained bleeding
 Bruising
 Blood in feces or urine
 Prolonged bleeding after injury
 Associated with coagulation disorders
 Increased risk of intra- and postoperative
hemorrhage

Other Considerations
 Written estimate
 Signed consent form
 Legally necessary
 Informs of risks
 Standard forms are available
 Owner’s daytime phone number
 Permission to perform CPCR
 Lists extralabel drugs used

Physical Examination (PE) vs.
Physical Assessment (PA)
 PE
 Performed by a veterinarian
 To determine diagnosis and treatment planning
 PA
 Performed by a veterinary technician
 To provide patient care, respond to patient needs,
detect changes in patient condition
 PE and PA
 Both necessary and important to ensure high
quality of patient care

Physical Examination/Physical
Assessment
 Examine the entire patient
 Use a consistent technique
 Head to tail
 Organ system
 Cardiovascular, nervous, and pulmonary
systems are most affected by anesthetic
agents

Patient Identification
 Cage tags
 Patient identification collars
 Document external characteristics in medical
record
 Species and breed
 Size
 Hair coat length
 Color

Body Weight
 Must be accurate for proper dosing
 <5 kg use a pediatric scale
 <1 kg use a gram scale
 Horses—estimated weight
body weight (kg) = heart girth (cm)2 × length (cm)
11880
 Weigh animals immediately before anesthetic
procedure
 Compare current weight with previously recorded
weight

Body Condition Score
 Assessment of patient weight to the ideal
weight
 A numeric assessment
 1-9 scale
• 4-5 in dogs or 5 in cats is the ideal weight
• 1 is extreme cachexia; 9 is extreme obesity
 1-5 scale
• 3 is the ideal weight
• 1 is extreme cachexia; 5 is extreme obesity
 Body condition influences patient
management

Hydration Assessment
 Skin turgor
 Placement of eye in orbit
 Mucous membrane color, refill time, moisture level
 Heart rate and pulse strength
 Correct hydration abnormalities prior to anesthesia
 Young and obese patients appear more hydrated
 Old and cachectic patients appear less hydrated
 Panting dries the mucous membranes

Level of Consciousness (LOC)
 To assess brain function
 Patient’s responsiveness to stimuli
 Healthy patients: alert, responsive, bright or
quiet
 Lethargic (lethargy)
 Obtunded (obtundity)
 Stuporous (stupor)
 Comatose (coma)

Pain Score
 Assess patient’s level of pain
 To help select preanesthetic and anesthetic
agents

Body Temperature
 Use a rectal thermometer
 Elevated = inflammation
 Decreased = numerous systemic disorders

General Condition
 Visual examination from a distance
 Gait
 Temperament
 Anxious or excited? Or ill?
 Activity level
 Exercise intolerance
 Weakness
 Will affect choice of anesthetic agents and
methods of administration

Exterior Surfaces
 Hair coat
 Skin
 Part the hair and look at the skin
 Lymph nodes and mammary glands
 Visual and manual examination
 Body openings
 Odors and discharges
 Eyes, ears, nose, oral cavity (throat)
 EENT

Pupillary Light Reflex (PLR)
 Normal—pupils are the same
size
 Direct reflex
 Consensual reflex

Cardiovascular System Examination
—Heart Rate
 Measured as beats per minute (bpm)
 Auscultation of left chest wall
 Large animal patients vs. small animal
patients
 Obese animals, panting dogs, purring cats
 Pediatric patients
 Exercise or stress of handling

—Heart Rhythm
 Evaluation of the heart rate
 Normal sinus rhythm (NSR)
 Dogs, cats, rodents, ferrets, rabbits, horses,
ruminants
 No rhythm irregularities
 Sinus arrhythmia (SA)
 Dogs, horses, ruminants
 Heart rate is affected by respiration

—Heart Rhythm (Cont’d)
 First degree atrioventricular (A-V) heart block
 Delayed conduction through the A-V node
 Detected only on ECG tracing
 Second degree A-V heart block
 Periodic block of conduction through the A-V node
 Results in skipped heartbeats

—Murmurs
 Listen over each valve
 Cranial-most aspect of left axilla—PDA
 Caused by blood flow turbulence
 May result in increased patient anesthetic risk

—Pulse
 Pulse palpation points
 Dogs and cats—femoral artery
 Large animals—facial artery, ventral tail artery, or
auricular artery
 Pulse deficit
 Blood pressure estimate

Cardiovascular System
Examination—Mucous Membrane Color
 Mucous membrane color
 Gingiva at base of tooth
 Alternate sites
 Pale or cyanotic membranes
 Capillary refill time (CRT)
 Normal = <2 seconds
 Prolonged refill time

Respiratory System Examination—
Breath Rate
 Measured in breaths per minute (bpm)
 Evaluated visually
 Inversely proportional to body size

Breathing Character
 Effort
 Dyspnea and cyanosis
 Relative length of inhalation and exhalation
 Regularity of inhalation and exhalation
 Inhale – exhale – rest – inhale –exhale –rest

Lung Auscultation
 Four quadrants
 Discontinuous sounds
 Continuous sounds

Abdominal Palpation and
Auscultation
 Normal is soft and not painful
 Firm or painful structures
 Abdominal distention
 Borborygmus—large animals
 Rumen contraction—ruminants

Preanesthetic Diagnostic Workup
 No one standardized diagnostic workup fits
every patient to be anesthetized
 Geriatric patient workup
 Elective surgery patient workup
 Sick patient workup
 Workup based on age, history, and physical
examination
 Workup based on financial considerations
 Completed after the patient history has been
taken and the physical examination has been
performed

Preanesthetic Diagnostic Tests
and Procedures
 Complete blood count (CBC)
 Urinalysis
 Blood chemistry
 Blood coagulation screens
 Electrocardiogram (ECG)
 Radiography
 Other tests as deemed necessary

Physical Status Classification
 Classification is based on an evaluation of the
Minimum Patient Database
 Rates patient anesthetic risk
 American Society of Anesthesiologists
 Class P1 = minimal anesthetic risk
 Class P5 = extreme anesthetic risk
 Classes P1 and P2 use standard anesthetic
protocol
 Classes P3 to P5 need special protocols and
stabilization

Anesthetic Protocols
 Established by the veterinarian
 Factors considered
 Facilities and equipment
 Familiarity with anesthetic agents
 Nature of the procedure
 Circumstances specific to a procedure
 Cost
 Urgency

Preinduction Patient Care
 Withholding food
 Complications
• Esophageal reflux, vomiting, regurgitation, pulmonary
aspiration, pneumonia
 if the patient is not fasted, one of several actions
must be taken.
 Preanesthetic with antiemetic properties
 Patient stabilization
 Sick patients
 Patients with concurrent conditions
 Reduces anesthetic risk

Intravenous (IV) Catheterization
 Reasons for placing an IV catheter
 Fluid administration
 Rapid IV access in an emergency
 Constant rate infusion (CRI) of drugs or anesthetic
agents
 Administration of vesicants
 Sequential administration of incompatible drugs

Intravenous Catheters
 Through-the-needle
 Over-the-needle
 Most commonly used
 16-24 gauge, 3/4- to 2-inch catheter (small
animals)
 12-16 gauge, 5¼-inch catheter (large animals)

IV Catheter Placement and
Maintenance
 Length
 Size
 Location
 Administration set with injection port
 Free-flowing fluids
 Minimal patient and catheter movement
 Slow administration
 Saline flush

Placing an IV Catheter in a Small
Animal Patient
Equipment

Animal Patient (Cont’d)
Clip area over the vein
Prepare the area using an aseptic technique
Place tape over the catheter hub
Hold off the vein, tense the skin, and position the catheter

Animal Patient (Cont’d)
Advance the catheter
assembly through the skin
Advance it further to firmly
seat in the vein
Advance the catheter over
the end of the needle
Remove the needle
Apply pressure

Animal
Attach T-port, cap, or set line to
the catheter hub
Secure the catheter with
tape
Flush the catheter with
saline
Twist the tape into a “bow-tie”

Animal (Cont’d)
Crisscross the tape under
and around the catheter
hub
Apply ointment to plastic
strip

Animal (Cont’d)
Apply the plastic strip over
the site of insertion
Secure the catheter with
tape

Animal (Cont’d)
Create a tension loop with tape

Giving an IV Injection Through an IV
Administration Set Port
Prepare medication or induction agent
Cleanse injection port with alcohol

Administration Set Port (Cont’d)
Insert the needle in the injection port
Pinch off the administration set line

Give medication at an appropriate rate

Release administration set line

Fluid Administration

Composition of Body Fluids
 Water
 Intracellular (ICF)
 Extracellular (ECF)
• Vascular
• Interstitial
 Other elements
(solutes)

Blood Volume
 Plasma is 5% of body weight
 Blood volume
 8-9% of body weight—dogs and large animals
 6-7% of body weight—cats
 Calculating blood volume
 Dogs and large animals = 90 mL/kg lean body
weight
 Cats = 60 mL/kg lean body weight

Solutes
 Ions—small molecular weight and electrically
charged
 Electrolytes
• Cations—positive charge
• Anions—negative charge
 colloids—large molecular weight plasma
proteins
 Small nonionic particles

Important Electrolytes
 Cations
 Sodium (Na+
)
 Potassium (K+
)
 Magnesium (Mg2+
)
 Calcium (Ca2+
)
 Anions
 Chloride (Cl−
)
 Bicarbonate (HCO3
−
)
 Phosphates (HPO4
2−
and H2PO4
−
)
 Proteins

Homeostasis
 A constant state within the body created and
maintained by normal physiologic processes
 Water and solute movement
 Passive diffusion
 Active transport
 Composition of fluid compartments varies
normally
 ICF: K+
, Mg2+
, protein, and phosphate
 ECF: Na+
, Cl−
, HCO3
−

Principles of Water and Solute
Balance
 In any given compartment, positively and
negatively charged particle numbers must be
equal.
 Solute concentration (osmolarity) in any fluid
compartment must be 300 mOms/L.
 Solutes must provide osmotic pressure to pull
water into a compartment.
 Small solutes (ions) pass freely into and out
of the intravascular space from the interstitial
space. Water follows to create equilibrium.

Principles of Water and Solute
Balance (Cont’d)
 One-third of IV fluids administered will stay in
the intravascular space. Two-thirds will diffuse
into the interstitial space.
 Colloids don’t pass freely through the vascular
endothelium.
 The presence of colloids in the intravascular space
draws water into the space creating osmotic or
oncotic pressure.
 Some solute concentrations (Ca2+
, K+
) must be kept
within a narrow range to maintain normal heart
and muscle function.

Fluid Loss and General Anesthesia
 Dehydration, anorexia, general disease
condition
 Depletes ECF
 Administer fluids with a solute profile similar to
ECF
 Perioperative hemorrhage
 Loss from intravascular space
 Administer fluids with a solute profile similar to
ECF
 Administer hypertonic saline or colloid solutions

Fluid Loss and General Anesthesia
(Cont’d)
 Significant perioperative hemorrhage
 Loss of blood constituents, water, electrolytes
 Administer blood products
 Low albumin
 Administer blood plasma or colloid solutions

Intravenous Fluids
 Composition varies
 One or more electrolytes
 Dextrose
 Buffers
 Colloids
 Classification
 Crystalloid
 Colloid

Crystalloid Intravenous Fluids
 Water and small-molecular-weight solutes
 May contain dextrose and/or buffers
 Often used in anesthetized patients

(Cont’d)
 Isotonic, polyionic replacement solutions
 Similar to ECF
 Lactated Ringer’s solution (LR)
 Normosol-R (NR)
 Plasma-Lyte A and R (PA and PR)
 Isolyte S (IS)
 LR and PR contain calcium and cannot be
administered with blood products

(Cont’d)
 Isotonic, polyionic maintenance solutions
 For use over a longer time
 Contain less sodium and chloride
 Contain more potassium
 Contain lower concentrations of buffer
 Contain dextrose
 Normosol-M in 5% dextrose (NM5)
 Plasma-Lyte 56 in 5% dextrose (PL5)

(Cont’d)
 Normal saline (NS)
 Physiologic saline, 0.9% saline, or sodium chloride
0.9%
 Contains only sodium and chloride dissolved in
water
 Sometimes used instead of isotonic, polyionic
replacement crystalloid solution
 Used to bathe tissues during surgery
 Used to flush the IV catheter
 Used to flush body cavities

(Cont’d)
 Hypertonic saline solutions
 3%, 5%, 7%, or 23.4% solutions
 Administered with isotonic crystalloid fluids
 Used to treat acute shock

(Cont’d)
 Dextrose solutions
 5% dextrose in water (D5W) or 2.5% dextrose
 May be found in some maintenance polyionic
solutions
 Used to support blood sugar levels
 D5W is used to replace fluid loss due to
dehydration or heat stroke

Colloid Solutions
 Contain large-molecular-weight solutes
 Used to support blood volumes and blood
pressure
 Synthetic colloid solutions
 Hetastarch
 Stay primarily in intravascular space
 Blood products
 Plasma and whole blood
 Hemoglobin-based oxygen carriers
 Human or bovine hemoglobin
 No need for crossmatch

Fluid Selection
 Healthy animal undergoing routine surgery
 Isotonic, polyionic, replacement fluids
 Sick patients
 PCV =>20, TP =>3.5 g/dL
 Isotonic, polyionic replacement fluids

Administration Rate
 During routine anesthesia and surgery
 10 mL/kg/hr during the first hour
 5 mL/kg/hr during remainder of the procedure

Fluid Administration Rate—Isotonic
Crystalloids
 Excessive hemorrhage or hypotension
 40 mL/kg/hr (dogs and large animals)
 20 mL/kg/hr (cats)
 Shock
 90 mL/kg/hr as rapidly as possibly (dogs and large
animals)
 55 mL/kg/hr as rapidly as possible (cats)
 Shock and blood loss (large and small animals)
 7% hypertonic saline
 3-4 mL/kg slowly over 5 minutes
 Followed by isotonic crystalloid solution

Fluid Administration Rate—Colloids
 10-20 mL/kg/day (dogs and large animals)
 5-10 mL/kg/day (cats)
 Monitor to prevent overload, coagulation
disorders, and allergies
 Administer as a slow bolus
 Over 15-60 minutes (dogs and large animals)
 Over 30-60 minutes (cats)

Adverse Effects of Fluid
Administration
 Volume overload
 Pulmonary or cerebral edema
 Use slower infusion rate
 Overhydration
 Ocular and nasal discharge
 Chemosis
 Subcutaneous edema
 Increased lung sounds
 Increased respiratory rate and dyspnea
 Coughing and restlessness if patient is awake
 Hemodilution

Fluid Administration
Infusion pump Tape scale to monitor rate

Fluid Administrations (Cont’d)
Burette for small-volume use

Definitions
 Prescribed rate
 Infusion rate
 Delivery rate
 Drip rate
 Infusion time
 Infusion volume
 Conversion factors

Infusion Sets
Macrodrip set chamber
(15 gtt/mL)
Microdrip set chamber
(60 gtt/mL)

Fluid Administration Rate
 Infusion rate
 Use patient weight and prescribed rate
 Drip rate
 Use infusion rate, delivery rate, conversion factors

Preanesthetic/Preoperative
Medications
 Antibiotics
 Preemptive analgesia
 Antiemetics
 Anticonvulsants
 Antiinflammatory drugs

Patient preparation

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