Anesthesia- Special Techniques – Flashcards

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Define LOCAL anesthesia.
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-drug used on sensory neurons to *disrupt nerve impulse transmission* causing loss of sensation.
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When is LOCAL anesthesia indicated?
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-TRACTABLE animal -General anesthesia high risk or NOT available
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What are the *advantages of LOCAL* anesthesia?
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-LOW cardio *toxicity* -LOW *cost* -*P*ost-op *P*ain *C*ontrol fast -LOW Recovery Time
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MOA of LOCAL anesthetics?
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-Affect SENSORY NEURONS -Blocks *sodium channels* and prevents (generation of) electrical impulses (stops depolarization)
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List LOCAL anesthetics USED on SKIN & MM's.
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Lidocaine Procaine Bupivacaine
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List 2 LOCALS USED in *OPTHALMIC* exams.
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Tetracaine Proparacaine (Precious' eye)
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-USES of LOCALS in L.A.
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*NERVE BLOCKS* most common in L.A. -*LAMENESS* in HORSES -*BLOCKS for DEHORNING* cattle -*Paravertebral BLOCKS* in cattle -*C-section / OBSTETRICS* (they don't cross placenta!)
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MOA of a TOPICAL LOCAL anesthetic?
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Affect the *ANS*! -Affect neurons btwn *Brain, Blood vessels and Organs*
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List the Clinical applications for LOCALS(I think).
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*Lidocaine patches* *Ethyl Chloride* spray *MM* application *Splash BLOCK* *Bupivacaine* thru chest tube
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-Does *TOPICAL* application have a *Shorter or Longer* DOA than *INFILTRATION*? -*Less or More* Analgesia?
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*SHORTER DOA* *LESS* Analgesia
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MOA for LOCALS *by* INFILTRATION?
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Drug injected into tissues in proximity to TARGET NERVE
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What is one *FORM* of INFILTRATION?
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*Paravertebral anesthesia*- -for Standing Laparotomies as *alternative to L-Block*
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List 3 different *methods of INFILTRATION*.
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L- block NERVE block RING block
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Does *INFILTRATION provide Analgesia* for surgery?
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For surgery involving SUPERFICIAL tissues
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Outline the procedure for administering a *LOCAL by INFILTRATION*.
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1.) Surgical prep 2.) Small-gauge needle (20 or 25 gauge) (cont'd?- can't see it)
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Why is EPINEPHRINE added to LIDOCAINE *prior to injection*?
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-affects *Rate of Absorption*
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What are 2 things that affect DOA?
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1. Drug used 2. Rate of Absorption by local blood vessels
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List the *INFILTRATION techniques*.
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*Paravertebral anesthesia*- -For Standing Laparotomies as an *alternative to an L-Block* -LOCAL BLOCKS the Dorsal & Ventral branches of spinal nerves *T13 - L12*
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Define NERVE BLOCK.
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Injecting *LOCAL in proximity to a NERVE* to DESENSITIZE particular site
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What are the *advantages* of a NERVE BLOCK?
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-To DESENSITIZE particular site -*Decreases general anesthesia* needed -Provides Short-term Analgesia Post-Op
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*Nerve Blocks are commonly used* in what animals?
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-*LARGE animals*
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List some USES of Nerve Blocks.
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-*DENTAL Blocks* (Dogs/Cats) -Intercostal Nerve Blocks for *chest surgery* -*Limb amputations* -*Declaws*
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Define *LINE BLOCK*.
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*LINE of LOCAL* placed betwn *TARGET AREA and SPINAL CORD*
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Define *RING BLOCK*. -When is this USED?
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*LINE of LOCAL* that *completely ENCIRCLES* an area -USED in *FOOD animal and EQUINE Sx* - Tx *Teat or wound* (Sx/repair)
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Define L-BLOCK.
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-*Line Block for LAPAROTOMY Sx* in RUMINANTS
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Define *Intraarticular* INFILTRATION.
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LOCALS injected directly into JOINT
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Define REGIONAL anesthesia.
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LOCAL injected into a *NERVE PLEXUS* or proximal to SPINAL CORD (affects larger area like an entire limb)
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-Define *Paravertebral anesthesia*. -What spp?
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For Standing LAPAROTOMIES as an *alternative to an L-Block* *RUMINANTS ONLY*
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Define *Epidural anesthesia*. What does it affect?
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A *REGIONAL BLOCK of SENSATION and MOTOR control* of rear, abdomen, pelvis, tail, pelvic limbs and perineum
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When could an EPIDURAL be USED?
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TAIL amputation ANAL SAC removal PERIANAL surgery Urethrostomies
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What determines the drug USED in an EPIDURAL?
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The *PROCEDURE*
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List the drugs USED in an EPIDURAL.
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-*2% Lidocaine or 0.5% Bupivicaine* -- LOCAL -*OPIOID (Morphine)*-- POST-OP Pain control -*OPIOID & LOCAL mixture* -- Anesthesia, Analgesia -*OPIOID & ALPHA2-AGONIST mixture*-- Epidural in Horses and Cattle
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*Where is an EPIDURAL* administered?
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Epidural space btwn *Spinal Cord and Vertebrae* -*Dogs*: btwn the *last Lumbar Vertebra (L7) and the Sacrum*
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-Define *Bier Block*. -What drug is USED?
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*IV REGIONAL anesthesia* -Lidocaine ONLY
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What does a *Bier Block* provide?
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Short-term *LOCAL to a LIMB*
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-Outline the procedure for a BIER BLOCK. -How long do the effects last?
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-*Tourniquet* applied to *PROXIMAL superficial vein* -*Lidocaine* injected into *DISTAL superficial vein* -Lasts *< 1 hour*
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What is the benefit of *Systemic Constant Rate Infusion* of Lidocaine?
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*LESS anesthesia or analgesia* required
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What are the *Adv. Effects* of LOCALS?
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-LOSS of *motor neuron function* -LOSS of *nerve function* w/ DIRECT injection -*Paresthesia* during Recovery -*Allergic rx* --from rash or hives to anaphylactic shock
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List the 3 different types of VENTILATION.
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*"PAC"* *Positive-Pressure* Ventilation (PPV) *Assisted* Ventilation *Controlled* Ventilation
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Define *Assisted ventilation*.
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-Anesthetist delivers an *INCREASED VOLUME of air or Oxygen/Anesthetic* to patient -*PATIENT INITIATES inspiration*
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Define *Controlled ventilation*.
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-Anesthetist delivers *ALL AIR REQUIRED* by the patient -*ANESTHETIST CONTROLS* Resp Rate and Volume & Pressure of gas
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Define *Normal ventilation*.
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Physical *movement of air into and out of the lungs and upper respiratory* passageways
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Outline the *Active Phase* of Normal ventilation.
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*INHALATION* -*Increased PaCO detected* by Respiratory center in the Brain -*Thoracic muscle movement* causes thoracic cavity to expand -Air is pulled into the breathing passages and goes to the alveoli
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Outline the *Passive Phase* of Normal ventilation.
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*EXHALATION* -*No active muscle movement* -PaCO begins to rise until respiratory center starts inhalation again -*2x's as long* as inspiration -Normal tidal volume = *10-15 mL/kg*
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How does Ventilation in *anesthetized animals* differ from an *awake animal*?
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*REDUCED amount of air* entering and leaving the lungs
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How do *tranquilizers and general anesthetics* affect ventilation?
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-*DECREASE responsiveness of breathing center to CO2 levels so inhalation doesn't occur as often*; (why CO2 is important in breathing!) -*Relax intercostals muscles and diaphragm* so the chest doesn't fully expand (Vt is reduced)
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List *3 MAJOR PROBLEMS associated with ventilation of anestheized animals*.
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HYPERCARBIA HYPOXEMIA ATELECTASIS
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Define HYPERCARBIA.
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Breakdown of *CO2 → Bicarbonate ions and H+ ions* -can lead to *respiratory acidosis*
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Define HYPOXEMIA.
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LESS Oxygen entering the lungs to be absorbed into blood
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Define ATELECTASIS.
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DECREASED Vt so *alveoli don't fully expand on inhalation*, which can lead to *collapse of the alveoli* in some sections of the lung
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Outline *Positive Pressure Ventilation*.
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-Pt. *intubated and connected to anesthetic machine -*Manual ventilation or bagging* (bags patient every *2-5 minutes*) -Pt. *REQUIRES bagging*
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Outline *Manual Ventilation*.
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-*Lungs are filled* with oxygen by pressure of gas entering airways -Anesthetist *squeezes reservoir bag* -*Pop-off valve* is fully or partially CLOSED -Passive Exhalation occurs when Positive Pressure STOPS and pop-off valve is OPENED -- *allows lungs to empty* -Bag *1-2 breaths every 2-5 minutes* (sighs) -Bag squeezed for 1-1.5 seconds (INHALATION time) Pressure manometer reading: *<20 cm HO* (small animals); Pressure manometer reading: *<40 cm HO* (L.A.) (right)?????????????
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Outline *Mechanical Ventilation*.
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Lungs are filled with oxygen by pressure of gas from a ventilator
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List the risks of CONTROLLED ventilation.
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-Ruptured alveoli -Decreased cardiac output -Respiratory alkalosis -Ventilator delivers more inhalant anesthetic to patient -Anesthetist monitoring
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Define Neuromuscular BLOCKING agents.
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*Muscle-paralyzing* agents
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What *surgical procedures* are Neuromuscular BLOCKERS USED for?
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-*LIMITED USE in Vet Med*- -*Orthopedic & Ophthalmic* sx -*C- section*
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What is the *MOA of a depolarizing* NM BLOCKING agent?
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*Interrupt normal impulse transmission* from motor neuron to muscle synapse
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List *1 depolarizing NM BLOCKING agent*.
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*Succinylcholine*
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-Does *Succinlycholine* have a Short or Long DOA? -What procedure is it USED for?
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*SHORT* DOA -*RAPID intubation*
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What is the *MOA of a NONdepolarizing* NM BLOCKING agent?
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(The *SAME*?) Interrupt normal impulse transmission from motor neuron to muscle synapse - Block receptors at end plates - No initial surge of activity
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List *NONdepolarizing* NM BLOCKING agents.
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Gallamine Pancuron*ium* Atracur*ium* Besylate
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What may *affect potency* of NM BLOCKING agents?
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Use with OTHER drugs
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How are NM BLOCKING agents administered?
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*SLOW IV* injection
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How *fast are the effects seen* from NM BLOCKING agents and what is the *DOA*?
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-Effect seen *within 2 minutes* -Lasts *10-30 minutes*
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What may be *difficult to assess* in NM BLOCKING agents ?
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Anesthetic depth
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What is a *Reversal agent* of NONdepolarizing NM BLOCKING agents?
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*Anticholinesterase* agent
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List 3 *Anticholinesterase agents.*
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Pyridostig*mine* Neostig*mine* (Reversals for *NONdepolarizing* NM BLOCKERS) (ANTI--antagonist!)
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--What should the patient be *pretreated with to prevent adverse effects*?
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-Atropine or Glycopyrrolate What type of drugs are these?
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Do Depolarizing agents have a *REVERSAL*?
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NO
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