VETS 238 Surgical Nursing and Anesthesia

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VETS 238Surgical Nursing and Anesthesia

• Spring 2006

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Welcome to Surgical Nursing and Anesthesia

• Dr. Bret Meckel
• Graduate of Texas AM College of Veterinary
  Medicine
• 8 years in private practice in Southern Oregon
• Three different small animal practices
• Primary vet for the Oregon Tiger Sanctuary
• Started teaching at Delhi in Spring 06

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Class 1

• Introductions
• Who are you?
• Name, where from, interests in veterinary
  medicine
• VETS238 Syllabus Lecture Outlines
• VETS239 Syllabus
• VETS239 Lab Guidelines
• VETS239 Lab Schedule
• Academic Integrity Policy
• Safety Release Form

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Any Questions?
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The Preanesthetic Period

• Read over notes and corresponding text for next
  class
• Be prepared!

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Quick Survey

• Currently working at a practice?
• LA vs SA?
• Anesthetics?
• Injectable
• Gas

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Preanesthesia

• What is it? What comes to mind?

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The Preanesthetic Period

• When?
• The period preceding induction of anesthesia
• Preanesthesia, induction, maintenance, recovery

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Preanesthesia (cont)

• Major functions of technician
• 1) Obtain information
• Preanesthetic forms, history, PE, Dx tests
• 2) Patient Care
• Fasting, iv catheter, walking
• 3) Administering drugs
• As directed by veterinarian

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Patient Evaluation/ Information Collection

• Remember Patients Vary Greatly
• So need to get standardized information
• minimum data base

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Minimum Data Base

• Paperwork
• Patient History
• Physical Examination
• Diagnostic Tests

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Paperwork/Information Collection

• Consent Forms
• Filled out/signed by owner
• anesthesia consent, DNR, IV/Bloodwork waiver
• Estimates
• No surprises

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Patient History

• Information from questions to owner
• Chief Complaint main problem (according to O)
• Whats wrong with ______ today?
• How used
• Observations
• Objective facts and information
• ie not urinating very much
• Interpretations
• Subjective adds evaluation to information
• ie dehydrated vs blocked?

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History Taking

• Not yes/no questions
• People avoid I dont know
• Not leading questions
• ie - drinking too much?
• Persist until adequate answer received
• Ie one cup of food per day
• Examples pg 3 VAA

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Physical Examination

• Signalment
• 1)Species and breedWhy Important?
• 2)Weight (possible complicating factor for
  anesthesia)
• 3)Age
• geriatric? Depends on breed
• 4)Sex with reproductive status (M/F S/N)
• ie prostate or pyometra
• 5)Disposition and Activity Level
• Helps determine drug choice, suture, e-collar

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Hands On Exam (read section in VAA)

• By body system
• Front to Back
• Back to Front
• Top to Bottom
• Key is to do it the SAME every time or youll
  miss things

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In Record by Body System

• Temperature, heart rate and respiratory rate
  (TPR)
• Auscultate the heart and lung and note any
  unusual characteristics and if necessary postpone
  the anesthesia until fully clear the questionable
  condition.
• Body condition obesity, cachexia, dehydration
• Cardiopulmonary system heart rate and rhythm,
  auscultate the characteristics, CRT, color of
  mucous membrane, exercise intolerance, coughing,
  dyspnea
• CNS and special senses temperament, seizure,
  coma, stupor, ataxia, vision and hearing
  impairment
• Gastrointestinal auscultate the gut sound,
  parasites, palpatition
• Hepatic icterus, abnormal bleeding
• Renal palpate kidneys and bladder,
  polyuria/polydipsia, oliguria
• Integument tumors and flea infestation
• Musculoskeletal fractures, deformity, and
  lameness

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Diagnostic Tests

• No Universal Guidelines
• Will depend on work place
• Clinic Policy vs Vet Decision

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CBC

• RBC / Hbg (O2 carrying capacity)
• Anemia
• PCV
• RBC
• Low means?
• TPP (TP) albumin immunoglobulins
• High vs Low?
• WBC differential
• Infection (bacterial or parasitic) or Leukemia

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Urinalysis (UA)

• Specific Gravity
• Concentration
• High vs low?
• Chemistries
• Protein/Glucose significance?
• Microscopic Exam (sediment)
• Crystals, RBC, WBC, casts

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Blood Chemistry Panel

• Checks Organ/ Hormone Function
• Liver
• Kidney
• Diabetes Screen
• Pancreas
• Electrolytes
• Ca,K,Na,Cl

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Blood Clotting Tests

• IN HOUSE
• Nail cut
• Buccal Bleeding
• ACT (Activated Clotting Time)
• TO LAB
• PT/PTT
• Especially consider in ?

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ECG

• Determines rate and rhythm of cardiac contractions

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Radiography

• Plain/Contrast Films, Ultrasound, CT, MRI
• If warranted
• HBC
• Possible Malignancy
• Otherwise called for in PE

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Misc. Tests

• Heartworm Test
• Blood Gases

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Procedure to be performed

• Length of time
• Catheter?
• Antibiotics
• Open GI Tract, Urinary Tract, Orthopedic
• Antibiotics!

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Classification of Patient Physical Status

• Used w/ minimum data base to determine
  appropriate anesthetic protocol
• Classes I-V (see page 15 in VAA)
• Example
• 1 yr old hyper young lab class I
• Injectables w/ heavy sedation
• 10 yr old intact male blocked cat class V
• Mask down

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Selection of the Anesthetic Protocol

• Factors that affect selection of the anesthetic
  protocol (Other than the patients physical
  status)
• 1. Availability of equipment and facilities
• Anesthetic machine?
• 2. Familiarity with the agent and the anesthetic
  protocol
• Safest drug is the one youre used to
• 3. Nature of the procedure
• Painful? Long? Local?
• 4. Special patient circumstances
• Pregnant animal/ C-section
• 5. Cost of anesthetic agents
• Important but remember 2
• 6. Speed of induction and recovery
• Emergency? End of day?

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Preanesthetic Patient Care

• 1). Withholding food and water before anesthesia
• Why? Dont assume!
• Duration food 8 hr water 2hr?
• With GI procedures
• food 24 hours if possible water
  8hrs?
• Risks
• Dehydration anesthesia risk factor
• Hypogycemia esp. puppies/kittens
• anorexia delays healing/recovery

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Preanesthetic Patient Care

• 2) Correction of pre-existing problems
• correct if possible but weigh the risks
• ie UTI in blocked cat
• 3) Intravenous Catheter and Fluid Therapy
• nice to have started couple hours before
  surgery if possible
• 4) Other Care
• walking, antibiotics, other meds?

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About any drug we discuss

• You NEED to Know
• Class and MOA
• Common and Trade Name
• Common route(s)
• Indications (why we use)
• What effects it has (good and bad)
• Contraindications (when not to use)
• Reversal agent if applicable

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PREANESTHETIC AGENTS

• Reasons for use
• 1. to calm or sedate the patient
• 2. to reduce or eliminate possible adverse side
  effects
• 3. to reduce the amount of general anesthetic
  required
• 4. to decrease pain and discomfort
• BUT remember
• NO preanesthetic agent is entirely free of side
  effects
• NO single preanesthetic agent is safe for every
  animal
• ALL preanesthetic agents (except glycopyrrolate)
  cross the placenta

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ANTICHOLINERGICS (parasympatholytics
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• ATROPINE
• Caution
• LA vs SA concentrations
• Not in tachycardia or GI obstruction/constipation
• Mode of action
• Acts in parasympathetic component of autonomic
  nervous system
• Blocks receptors for the neurotransmitter
  acetylcholine at muscarinic receptors (heart, GI,
  bronchi, salivary glands, iris)
• Inhibits parasympathetic effects
  parasympatholytic

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Effects of atropine

• 1. Blocks stimulation of the vagal nerve
• Major parasympathetic innervation to heart
• Therefore increases HR
• 2. Reduces production of saliva
• 3. Reduces GI activity
• 4. Causes dilation of pupils
• 5. Reduces tear production
• 6. Promotes bronchodilation
• 7. May produce thick mucus within the
  airways

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Atropine toxicity

• Signs
• Dilated pupils, tremors, ataxia
• Due to excessive supression of parasympathetic
  response
• Tx Physostigmine
• Real problem?

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Use of atropine controversial!

• Needed with newer drugs?
• Potential for adverse side effects/toxicity
• Onset of action
• 15 min SQ/IM
• Within 1 min IV
• Duration of action
• 60-90 min practical?
• I like it in dogs but not in cats

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GLYCOPYRROLATE

• effects similar to atropine
• Advantages of glycopyrrolate
• Effects last 2-3X as long as atropine
• Less tachycardia
• More effective at supressing salivation
• Doesnt cross placental barrier
• BUT Atropine superior in bradycardic situation

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TRANQUILIZERS AND SEDATIVES

• Main reasons for use
• Calm animal for easier handling and induction
• Easier recovery for animal (ie ferals)
• Four classes of Tranquilizers/Sedatives
• Phenothiazines
• Benzodiazepines
• Alpha 2 Agonists
• Opioids

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PHENOTHIAZINES

• -promazines ACEPROMAZINE
• Effects of phenothiazines
• 1.) Sedation up to 24 hours
• 2.) Anti-emetic -- decreases nausea
• 3.) Anti-arrhythmic helpful with some
  anesthetics (halothane)
• 4.) Anti-histamine not in allergy testing
• 5.) Peripheral vasodilation not ideal in low
  blood pressure/shock
• 6.) Effects on personality can cause
  excitement
• Disadvantages of phenothiazines
• NO ANALGESIA
• NO REVERSING AGENTS
• LOWER SEIZURE THRESHOLDS
• MANUFACTURERS RECOMMENDED DOSES EXCESSIVE
• Decrease by 50 or risk hypotension

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BENZODIAZEPINES

• -ams examples diazepam (valium),
  zolazepam (in telazol)
• MOA cause release of nuerotransmitter GABA in
  brain
• Effects of benzodiazepines
• 1. Reduces anxiety (little sedation)
• 2. Skeletal muscle relaxant (counter acts
  ketamine)
• 3. ANTICONVULSANT increases seizure threshold
• 4. Minimal adverse effects
• except in liver disease and neonates?? (poor
  metabolism )
• 5. appetite stimulant/cats 0.05 cc IV valium
  magic
• 6. modify behavior (inappropriate urination)
• BUT NO ANALGESIA
  ADDICTIVE(paperwork)

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Use of benzodiazepines

• Diazepam ( Valium )
  IV slowly (or IM)
• NOT water soluble (precipitates w
  other drugs)
• Soluble in plastics
  
• light-sensitive
• controlled substance
• Commonly used in combination with drugs that
  induce anesthesia
• 2. Midazolam ( Versed )
• Advantages
• water soluble
• less irritating

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ALPHA 2 AGONISTS (receptor in brain)
(engage these receptors)

• thiazine derivatives
• examples xylazine (rompun, anased),
  medetomidine (Domitor)
• widely used in SA and LA potent
  sedatives not controlled substances
• fast onset predictable results
  reversible ANALGESIA
• yohimbine (antisedan)
• Mode of action bind to receptors on
  sympathetic nerves in brain and spinal cord
• stimulate these alpha 2 adrenoreceptors (result
  is decrease in norepinephrine)
• yielding muscle relaxation
  sedation analgesia (short 20min)
• metabolized in the liver, metabolites excreted
  in the urine
• BUT similar receptors in the heart and blood
  vessels gtgtgtgt side effects
• decrease HR, decrease BP

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Use of alpha 2 agonists

• Xylazine SA solution 2 LA solution
  10 mgs/mL
• used alone or in combination IM or IV
• 2. Medetomidine ( Domitor ) 1mg/mL
  approved for use in dogs only
• commonly used in combinations
  medetomidine(10ug/kg) butorphanol(0.2mg/kg)
  mixed and given IM

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Alpha Agonists ADVERSE EFFECTS

• significant, frightening, check your own pulse
• 1. BRADYCARDIA decreases cardiac output
  second degree heart block
• sensitizes the heart to epinephrine gtgtgtgt
  cardiac arrhythmias
• Prevention Anticholenergics Treatment
  Yohimbine/ Atipamazole(5X dose)
• 2. Respiratory effects vary among animals
  respiratory depression to no ill effects??
• BLUE! d/t low bloodflow not hypoxia??
• 3. Vomiting 50 dogs 90 cats
  (less w/ metotomidine)
• 4. Depress GI activity gtgtgtgt GI stasis
  Beware of bloat (giant breeds)
• 5. Temporary behavior and personality changes
• 6. Reduce secretion of insulingtgtgtgtgttransient
  hyperglycemiagtgtgtgturination
• Use of Reversing Agents (have drawn up)
• yohimbine for xylazine (IV)
  atipamezole ( Antisedan ) for
  medetomidine (IM)
• may need to give an analgesic
  if reversed

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OPIOIDS

• aka narcotics or opiates (natural)
• Versatile-- can be used for
• preanesthesia, induction, analgesia
  (excellent)
• Very safe Wide safety margins
• Mode of action four types of opioid
  receptors throughout body
• Opioid agents differ in their action at each of
  these types of receptors
• agonist antagonist
  mixed
• pure agonists pure antagonists
  agonist/antagonist
• Morphine naloxone
  butorphanol
• fentanyl reversal agent
• oxymorphine

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OPIOIDs (cont)

• Effects
• 1. CNS effects may cause CNS depression or
  excitement
• dogs usually depression, high doses gtgtgtgt
  narcosis
• cats may show bizarre responses i.e.,
  excitement, anxiety
• 2. Analgesia the most effective analgesics,
  especially pure agonists (morphine)
• Method of use Opioid agents
• Common components of preanesthetic protocols
  (butorphanol)
• mixed with a tranquilizer and/or an
  anticholinergic
• Used to prevent and treat postoperative pain
• Neuroleptanalgesia profound sedation and
  analgesia, for minor surgery
• produced by doses of opioid (at a high dose)
  plus a tranquilizer

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OPIOIDS Adverse effects

• 1. Respiratory depression gtgtgtgt decreases
  respiratory rate and tidal volume
• 2. GI function initially, increased
  peristalsis then, GI stasis gtgtgt constipation
• 3. Addiction physical dependence
  (controlled drugs PAPERWORK)
• 4. Drug interactions in patients on
  selegiline FATAL
• Reversibility can reverse the effects,
  esp. of pure agonists w/ antagonists
• Naloxone is preferred reversal agent, causes
  least respiratory depression
• Molecules of reversing agents bind to the opioid
  receptor sites
• act as blocking agents or displace molecules
  of pure agonists
• but, reversal of analgesia also occurs
• Disadvantage , not routinely necessary
  except in emergencies??

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