Anesthetic Principles

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Anesthetic Principles
2014-04-19 11:26:56
VTHT Anesthesia Surgery

aspects and consideration for anesthesia
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  1. The means the loss of sensation
  2. This refers to the reversible state of unconsciousness, immobility, muscle relaxation and loss of sensation throughout entire body
    General anesthesia
  3. This refers to the specific stage of general anesthesia that allow procedures to be performed without pain or movement
    surgical anesthesia (stage 3 plane 2)
  4. This refers to a drug-induced CNS depression and drowsiness with mild analgesia
  5. This refers to a drug induced state of calm and unconcern without analgesia
  6. This refers to the stage of anesthesia where the patient is awake by may react unpredictably
    pre-narcosis : stage 1
  7. This refers to the stage of anesthesia where the patient loses consciousness but still has all reflexes
    narcosis : stage 2
  8. Which stage of anesthesia is a bite likely to occur?
    narcosis : stage 2
  9. This refers to the stage of anesthesia where the swallowing reflex is abolished and intubation can take place
    Unconsciouness : stage 3 plane 1
  10. This refers to the stage of anesthesia where most reflexes are abolished and surgical intervention can take place
    surgical : stage 3 plane 2
  11. This is a sub stage of unconsciousness where respirations fall below 12/min, blood press is less than 79 mmHg, capillary refill time > 2 second and under the tongue is gray with lowered oxygenation
    Stage 3 plane 3
  12. This is a sub stage of unconsciousness where cardiac and respiratory arrests begin, eyes fully dilate and remain fixed
    Stage 3 plane 4
  13. This refers to the stage of anesthesia where complete cessation of respiration and total circulatory collapse occur
    Death : stage 4
  14. An artificially induced sleep with marked analgesia although there is some visceral pain
  15. This refers to the loss of sensation in a small area of the body produced by injection of anesthetic agent in proximity of the area of interest
    local anesthetic
  16. This type of anesthesia is the loss of sensation in a limited area produce by an agent injected in close to nerves supplying that area
    Regional anesthesia
  17. 2 types of regional anesthesia
    • nerve blocks
    • epidurals
  18. This is involuntary state of rigidity with analgesia, amnesia and immobility caused by CNS stimulation rather than depression often associated with cyclohexamines
  19. This refers to a type of anesthesia produced by combining a tranquilizer and an opioid
    neuroleptanalgesic - Innovar-vet
  20. What to drugs make up Innovar-Vet
    • droperidol (tranq)
    • fentanyl (Duragesic patch) (opioid)
  21. This type of anesthesia refers to the use of a combination of drugs in smaller quantities that maximized benefits, minimizes adverse affects and produces the appropriate degree of anesthesia to the patient and procedure
    Balanced anesthesia
  22. How must the anesthetist approach each and every anesthetic procedure?
    They must take a genuine interest in the well-being of the patient by taking personal responsibility
  23. These life phases are the most critical for all surgery patients
    • Pediatric
    • Geriatric
  24. This refers to a patient that has reached 75% of its life expectancy for that breed
  25. This means to give a drug until the desired level of effect is attained rather than the entire recommended dosage
    dose to effect
  26. With the exception of mitral valve insufficiency patients what is generally advocated for geriatric patients?
    Intravenous fluids
  27. Due to geriatric reduced tolerance to hypotension and ability to concentrate urine what is usually advocated until the time of anesthesia?
    Give access to water
  28. This means less than 2 weeks old
  29. This means between 2-8 weeks old
  30. At what ages do veterinarian commonly consider neonatal and pediatric?
    • neonatal: less than 3 months
    • pediatric: before the animal reaches puberty
  31. Considerations to aid the anesthetist
    • 1. Availability of equipment and facilities
    • 2. Familiarity with anesthetic agent
    • 3. Knowledge of procedure required
    • 4. Individual Patient Problems
    • 5. Cost of procedure
    • 6. Speed of surgeon
  32. What are the 3 general areas of breed considerations?
    • 1. Anatomical differences
    • 2. Variable responses regarding barbiturates
    • 3. Propensity of heat loss/gain
  33. Generally which dog breeds experience heat loss?
    toy breeds
  34. Generally which dog breeds experience heat gain?
    large fatty breeds
  35. What condition can arise regarding body temperature and the administration of sevo/isoflurane?
    Malignant hyperthermia
  36. Why is pre-operative fasting not recommended for neonatal patients?
    Hypoglycemia and dehydration are highly likely to occur
  37. Which crystalloid may be used instead of LRS in a neonatal patient?
    Dextrose 5% in water
  38. Why is it important especially with neonates to get an accurate weight before surgery?
    To calculate anesthetic doses correctly since the have a very narrow margin of error
  39. Why should injectable pre-anesthetics like acetylpromazine, xylazine or barbiturates be avoided in neonatal patients?
    Due to immature liver they are inefficient in metabolizing these drugs
  40. What is the preferred method of anesthetizing neonatal patients?
    Use of a mask to "gas down" the patient with inhalant anesthetics like sevo/isoflurane
  41. This term describes an animal that is 1/2 again over their optimal weight
    Grossly obese
  42. Patient Preparation steps:
    • 1. Preliminary General Examination
    • 2. Efforts made to correct any concurrent illness several days ahead
    • 3. Fast patient for 8-12 hours (water ok until anesthesia induction)
    • 4. Check all anesthesia and surgery equipment
    • 5. Ensure indwelling catheter is in place, patent and fluids are flowing
  43. Catheter benefits:
    • 1. Fluid administration during surgery
    • 2. Rapid administration of emergency drugs
    • 3. Multiple syringe drug administration
    • 4. Protects against perivascular irritation from highly alkaline drugs
    • 5. Prolonged administration of antibiotics/analgesic
  44. This type of catheter is primarily used in equine medicine that involves administering fluids through the jugular vein.
    Through the needle
  45. This type of catheter uses a long thin needle to insert it into the vein more commonly used with small animal practices.
    Over the needle
  46. This is the term for the long thin needle in a catheter
  47. Maintenance fluid rate for canines over 20lbs
  48. Maintenance fluid rate for canines 20lbs and under and felines
  49. Surgery fluid rate
  50. Shock fluid rate for canines
  51. Shock fluid rate for felines
  52. Rapid rehydration rate for canines
    20mL/# for the 1st hour then lower to maintenance rate
  53. Rapid rehydration rate for felines
    10mL/# for the 1st hour then lower to maintenance rate
  54. This type of fluid is commonly used during a state of acidosis (95% of shock patients)
    Lactated Ringers Solution
  55. This type of fluid is primarily used with vomiting and diarrhea cases
    0.9% Normal Saline

    note: replaces Na+(diarrhea) and CL-(vomiting) that is lost
  56. This type of fluid is primarily used in equine medicine during a state of alkalosis
    Ringers solution (is acidic)
  57. This is a blood substitute made from bovine hemoglobin that does not require blood typing
  58. Classes of drugs commonly used as pre-anesthetics
    • 1. Alpha-2 agonists
    • 2. Cyclohexamines
    • 3. Opioids
    • 4. Anticholinergics
    • 5. Tranquilizers
  59. Reasons for Pre-anesthetic use:
    • 1. Reduce the amount of general anesthetic required to induce anesthesia
    • 2. Calm or sedate excited/vicious animal
    • 3. Reduce side effects from general anesthetic use
    • 4. Decrease post operative pain/discomfort
  60. List Anticholinergic drugs:
    • Diethyl ether - no longer used
    • Atropine
    • Glycopyrrolate (Robinul)
  61. These causes of vagal bradycardia are the reason why anticholinergics are given
    • Manipulation of the eye
    • Traction of deep visceral organs
    • Direct vagal stimulation
    • Endotracheal intubation
  62. Effects of Atropine
    • 1. Increased heart rate
    • 2. Decreased saliva/respiratory secretions and intestinal motility
    • 3. Bronchodilation
    • 4. Mydriasis
  63. Manufacturers of atropine sulfate
    • Atoject - Vetus Animal Health
    • Atropine - Butler Company
  64. What is Atropine derived from?
    Atropa belladonna
  65. Atropine specific mode of action
    Competitive antagonist of muscarinic cholinergic receptors
  66. Species Atropine is approved for:
    • Dogs
    • Cats
    • Cattle
    • Horses
    • Sheep
    • Swine
  67. Advantages of Glycopyrrolate over Atropine
    • 1. No CNS effect/Does not cross blood-brain barrier
    • 2. Longer vagal blocking activity
    • 3. More pronounce antisialagoue
    • 4. Less tachycardia/arrythmias
    • 5. Longer half life
  68. This refers to the time it takes for the concentration of a drug in the blood to decrease by one-half.
  69. Glycopyrrolate dose strength
  70. Glycopyrrolate dosage
    0.005 - 0.010 mg/kg IV
  71. What is the disadvantage of glycopyrrolate
    Higer cost
  72. Atropine dosages
    • Dog/Cat/Horse: 0.01-0.02mg/kg IV
    • Cattle: 0.02-0.04mg/kg IV
  73. Manufacturers of Glycopyrrolate
    Robinul - Baxter Healthcare Corp.
  74. Species Glycopyrrolate is approved for:
    • Dogs
    • Cats
  75. Glycopyrrolate is what type of compound?
    Quaternary Ammonia Compound
  76. Specific method of action of Glycopyrrolate
    Muscarinic receptor antagonist
  77. What is the anticholinergic of choice for lagomorphs?
  78. The routine use of glycopyrrolate in horses can produce which conditions
    Ileus and colic
  79. Of the many reasons of choosing glycopyrrolate over atropine, these two are considered primary:
    • 1. longer acting
    • 2. safer on to use in animals with preexisting heart condition d/t less tendency towards cardiac arrhythmias/tachycardia
  80. This class of drugs produce a calm and unconcerned state but do not provide analgesia
  81. What is the primary disadvantage to tranquilizers?
    circulatory hypotension
  82. Phenothiazine traquilizer effects:
    • Lengthens the effect of general anesthetics and reduces the amount necessary
    • Antiemetic
    • Antihistamine
    • Antidysrrhythmic
    • Alpha 2 antagonist
    • Prolongs and ensure mild recovery when used with sedatives and hypnotics
  83. Onset of effect for Acetylpromazine
    • IM: 10-15 minutes
    • Oral: 1 hour
  84. Duration of Acetylpromazine
    • Generally 4-8 hrs
    • Geriatrics/hepatic dysfunction: up to 48 hrs
    • Cattle: 82 hrs
  85. Manufacturers of Acetylpromazine maleate
    • PromAce: Ft. Dodge
    • Aceproject: Vetus Animal Health
  86. Species Acetylpromazine approved:
    • Dogs
    • Cats
    • Horses - not intended for food
  87. Adverse affects of Acetylpromazine
    • Peripheral Vasodilation (hypotension)
    • Reduces seizure threshold
    • Splenic engorgement by sequestration of RBCs (drops HCT by 50%)
    • Priapism in stallions (penile prolapse)
    • Can inhibit temperature regulation
  88. The main difference between a sedative and a tranquilizer:
    Sedatives provide analgesia
  89. Thiazine Derivatives/Alpha-2 agonists:
    • Xylazine(Rompun/AnaSed)
    • Detomidine(Dormosedan)
    • Medetomidine(Dormitor)
    • Dexmedetomidine(DexDormitor)
    • Romifidine(Sedivet)
  90. General Sedative side effects:
    • Repiratory Depression
    • Bradycardia and hypotensive heart block
    • Rumenal Tympany
    • Hepato and Nephrotoxic
  91. Xylazine side effects:
    • Vomiting in cats (90%) and dogs (50%)
    • Reduces secretion of insulin causing transient hyperglycemia
    • Decreases minimum alveolar concentration & other requirements for other anesthetics
  92. Alpha-2 agonist method of action:
    Stimulate Alpha 2 adrenergic receptors of the brain and spinal cord to decrease the level of nor-epinephrine resulting in sedation/analgesia/muscle relaxation
  93. This drug is considered the prototypical Alpha-2 agonist
  94. In 1962 Xylazine was first synthesized for what purpose?
    Anti-hypertensive in humans
  95. What species of animal was Xylazine first used in Europe?
  96. Manufacturers of Xylazine
    • Sedazine - Ft Dodge
    • Rompun - Bayer
    • AnaSed - Lloyd Inc.
    • gen. Xylazine - Butler
    • X-ject E & SA - Vetus Animal Health
  97. Reversal agent for Xylazine
    Yohimbine (Yobine)
  98. Xylazine dose strengths
    • 20mg/mL (sm. animal/Cattle)
    • 100mg/mL (horses)
  99. Xylazine dosage
    0.25mL/20lb IV canine only
  100. Advantage of detomidine over xylazine
    2x the half life
  101. Detomidine should not be given to horses with which conditions?
    • 1. Renal disease
    • 2. Respiratory disease
    • 3. Colic pain
    • 4. Endotoxic shock
  102. This thiazine derivative has a higher than normal degree of selectivity for Alpha-2 binding sites
    Dexmedetomidine (DexDormitor) - Pfizer
  103. Dexmedetomidine onset times:
    • IV - 5 minutes
    • IM - 10 to 15 minutes
  104. Reversal Agent for Dexmedetomidine
    Atipamazole (Antisedan) - Pfizer
  105. Drugs in the Benzodiazepine class:
    • Diazepam (Valium) - human  C-IV
    • Zolazepam (only with Tiletamine in Telazol) C-III
    • Midazolam (Versed) - human C-IV
    • Lorazepam (Ativan) - human
  106. Benzodiazepine method of action
    Stimulates the release of gamma-aminobutyric acid (GABA) mainly but also some glycine to inhibit neurotransmission in the brain and spinal cord
  107. Diazepam common uses:
    • 1. Antianxiety - calming
    • 2. Skeletal muscle relaxation
    • 3. Anticonvulsant
    • 4. Relatively safe with patients with cardiac/respiratory issues
  108. Why is diazepam not drawn up ahead of time nor mixed with most drugs?
    It will absorb into plastic and is physically incompatible with most drugs because if its water insolubility
  109. What other considerations are there when handling/using diazepam?
    • 1. It is light sensitive
    • 2. Will cause cardiac arrhythmia if given rapidly
  110. What is the only benzodiazepine approved for cats and dogs?
    Zolazepam in Telazol
  111. Why is Telazol painful upon injection?
    low pH (2.2-2.8)
  112. Diazepam dosages
    • Dogs/cats - 0.1-0.2mg/kg IV
    • Horses - 0.01-0.03mg/kg IV
  113. Why must the corneas be protected from light and lubricated when Telazol is given?
    The cyclohexamine tiletamine will cause the eyes to remain open
  114. Advantages of midazolam over diazepam
    • 1. water soluble - can be mixed with other pre-anesthetics
    • 2. less tissue irritation
    • 3. quick onset - 3 min
  115. Drugs in the Opioid Class:
    • Morphine sulfate
    • Meperidine HCL (Demerol)
    • Pentazocine (Talwin)
    • Oxymorphone (Numorphan)
    • Hydromorphone (Dilaudid)
    • Butorphanol (Torbutrol,Torbugesic)
    • Fentanyl (Duragesic)
  116. Name the 5 opioid receptors:
    • Mu
    • Kappa
    • Sigma
    • Delta
    • Epsilon
  117. Opioid benefits:
    • 1. CNS receptors are stimulated (pure agonist) or blocked (mixed/antagonist)
    • 2. superior analgesia
    • 3. Do not cross blood-brain barrier
    • 4. Reversible
  118. The three most common opioid analgesics in veterinary medicine:
    • Fentanyl
    • Burtophanol
    • Hydro/Oxymorphone
  119. Opioid Adverse effects:
    • 1. Profound respiratory depression
    • 2. Bradycardia
    • 3. Increased intestinal peristalsis followed by stasis
    • 4. Physical dependence
  120. Which opioid is primarily a human drug but useful in cats at low dosages?
    Meperidine HCL (Demerol)
  121. Which opioid was replaced by Banamine for colic in horses?
    Pentazocine (Talwin)
  122. This opioid is no longer available in the US.
    Oxymorphone (Numorphan)
  123. This opioid replaced Oxymorphone
    Hydromorphone (Dilaudid)
  124. Which form of butorphanol is used in dogs as an antitussive?
    Torbutrol (0.5mg/mL)
  125. Which form f butorphanol is used in primarily in large animals?
    Torbugesic (10mg/mL)
  126. This refers to the combination of an opioid and a tranquilizer
  127. Name a commercially available neuroleptanalgesic and its constituents
    • Innovar-Vet
    • droperidol - tranquilizer
    • fentanyl - opioid
  128. Nickname for Malignant Hyperthermia
    Porcine Stress Syndrome
  129. As a result of Malignant Hyperthermia control of which mineral regulation is lost at the level of the skeletal sarcoplasic reticulum?
  130. What breed of dog does Malignant Hyperthermia occur in mostly?
  131. What breed of horse does Malignant Hyperthermia occur in mostly?
  132. This is the muscle relaxant used to pretreat animals to prevent Malignant Hyperthermia
    Dantrolene sodium (Dantrim)
  133. What type of gene is associated with Malignant Hyperthermia?
    Autosomal dominant
  134. This refers to the process by which an animal loses consciousness and enters surgical anesthesia
    Anesthetic induction
  135. What is the main goal of anesthetic induction?
    To take the patient from consciousness to Stage 3, plane 2 smoothly and rapidly in order to place an endo-tracheal tube
  136. List the injectable anesthetic by class (or drug if no class exists):
    • Barbiturates
    • Cyclohexamine/Hypnotic/Dissociative
    • Neuroleptanalgesics
    • Propofol
    • Etomidate
  137. List the inhalant anesthetics
    • Diethyl ether
    • Methoxyflurane
    • Nitrous Oxide
    • Halothane
    • Isoflurane
    • Sevoflurane
  138. Outline the phases of General Anesthesia
    • 1. Pre-anesthetic Phase
    •     a. Minimum Patient Database
    •     b. Fasted 8-12 hours
    •     c. Administer Pre-anesthetic drugs
    •     d. Administer Basal Anesthetic
    • 2. Induction Phase (Stg 3, pln 2)
    • 3. Maintenance Phase (maint of Stg3, pln 2 not motion)
    • 4. Recovery Phase (RVT solely responsible for patient's life)
  139. Steps for General Anesthesia Safety
    • 1. Know your drugs before administration
    •     a. how is drug eliminated
    •     b. which cross blood-brain barrier
    •     c. reversal agents available
    • 2. Preanesthetics to:
    •     a. reduce secretions and prevent bradycardia
    •     b. reduce amount of gen. anesthesia to speed induction/recovery
    • 3. Double check dosages with DrY/Denise/Kathleen
    • 4. Give basal to effect
  140. Pupil size in terms of anesthetic depth (not on anticholinergics)
    • Stage 1 - normal
    • Stage 2 - smaller diameter
    • Stage 3 - smaller still
    •     plane 1 - Same as stage 3
    •     plane 2 - same as stage 1
    •     plane 3 - Pupils start dilation
    •     plane 4 - Dilation continues
    • Stage 4 - complete dilation and fixed
  141. Procedure that constitute "no pain" requiring only moderate sedation with small analgesia
    • Physical examination
    • Radiography
    • Suture removal
    • Bandage change
    • Cast application
    • Nail trim
    • Grooming
  142. What is considered a minor pain level?
    Heavy sedation with analgesia or short anesthesia
  143. What procedures constitute minor pain?
    • Suturing
    • Debridement
    • Urinary catheterization
    • Dental cleaning
    • Ear treatment
    • Abscess lancing
    • Cutaneous growth removal
  144. What is considered a moderate pain level?
    • Needs pre-anesthetics
    • General Anesthesia
    • Possible post-op pain management
  145. What procedures are considered moderate pain level?
    • Ovariohysterectomy
    • Orchidectomy
    • Onychectomy
    • Cystotomy
    • Dental Extraction
    • Cutaneous Mass
  146. What is considered a severe pain level?
    • Analgesic premedication
    • General Anesthesia
    • Post-op pain management essential
  147. What procedures constitute severe pain level?
    • Fracture repair
    • cruciate ligament repair
    • Thoracotomy
    • Laminectomy
    • Amputation
    • Ear canal ablation
  148. List drugs in Cyclohexamine class:
    • Phencyclidine (C-I) "Angel Dust, PCP"
    • Ketamine (Ketaset, Vetalar, Vetamine, Ketaject)
    • Tiletamine - only as a component of Telazol
  149. Cyclohexamine effects:
    • Good somatic analgesia but not visceral
    • Induces catalepsy but is temporary
    • Lowers seizure threshold
    • Can be given orally to fractious animals
  150. Cyclohexamine recovery times:
    • Horses IV: 20-30 min
    • Dogs IV: 2-24 hours
    • Cats IM: 3-6 hours
  151. Two reasons why barbiturates are still used today.
    • 1. easy to administer
    • 2. inexpensive
  152. What are the 2 major drawbacks of barbiturates?
    • 1. Highly alkaline - will cause tissue necrosis down to the bone
    • 2. Short period of apnea
  153. How do barbiturates cause apnea and what drug was developed because of it?
    • 1. Causes a decreased response of the CO2 receptors in the Aortic arch and Carotid sinus
    • 2. Doxapram was developed to make the receptors more sensitive to CO2
  154. This is the term given to drugs like Doxapram that make receptors in the aortic arch and carotid sinus more sensitive to CO2
  155. Two ways in which barbiturates are classified
    • 1. By the length of their action
    • 2. By their side chain
  156. List the barbiturates according to their length of action.
    • Ultra short acting: 10 minutes
    •      Thiamylal sodium (Biothal)
    •      Thiopental sodium (Pentothal)
    •      Methohexital (Brevane)
    • Short acting: 45 min - 1hr
    •      Pentobarbital
    • Long acting: 6-7 hrs to 24 hrs
    •      Phenobarbital
  157. List the barbiturates according to their side chain
    • Oxybarbiturates (oxygen)
    •      Pentobarbital
    •      Phenobarbital
    • Thiobarbiturates (sulfur)
    •      Thiamylal sodium (Biothal)
    •      Thiopental sodium (Pentothal)
    •      Methohexital (Brevane)
  158. This term refers to a drug that has been around so long that it no longer has a proprietary name
  159. All opioids are reversible by these two drugs:
    • Naloxone (Narcan)
    • Nalorphine (partial antagonist)
  160. This opioid is used exclusively by zoos and wildlife parks and is considered the most concentrated of the opioids
    Etorphine (M-99)
  161. Advantages of propofol
    • Ideal for short procedures without gas
    • Easy induction and transition to gas
    • Safe for sighthounds and geriatrics
    • Minimal effect on cardio and respiratory systems
    • Full standing recovery in 20 minutes
    • Repeat doses will not increase recovery time
  162. Disadvantages of propofol
    • Cost
    • Rapid administration can cause cardiopulmonary depression
    • Because it is an emulsion, vials are single use to prevent bacterial contamination
    • Injections need to be titrated to patient's response
    • May induce myoclonus
  163. Propofol dosage
  164. Manufacturers of Propofol
    • PropoFlo - Abbott Laboratories
    • Propofol - Baxter
    • Rapinovet - Schering-Plough
  165. Species approved for Propofol
    • Dogs
    • Cats
  166. This is a brief involuntary twitching of a muscle or muscle group often seen with propofol use.
  167. This is a condition in cats repeatedly dosed with propofol.
    Heinz bodies - hemoglobin precipitates out of the red blood cell
  168. These two chemicals are produced by the body that stimulate the opioid receptors.
    • Endorphins
    • Enkephalins
  169. These 4 drugs stimulate all 4 opioid receptors
    • Morphine sulfate
    • Meperidine (Demerol)
    • Fentanyl (Duragesic)
    • Hydromorphone (Dilaudid)
  170. This opioid is considered a pure antagonist thus the reversal agent that acts on all opioid receptors
    Naloxone (Narcan)
  171. This opioid receptor is more known for producing euphoria and hallucinations (dysphoria) when stimulated
  172. These two opioid receptors both produce sedation, analgesia and respiratory depression when stimulated.
    • Mu
    • Kappa
  173. This opioid receptor is more known for producing motor dysfunction as well as analgesia.