Anesthesia: Regional Anesthesia/Analgesia Techniques – Flashcards
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We should not use benzocaine and prilocaine in which species?
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Cats, ferrets, and other exotic animals
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Why should benzocaine and prilocaine not be used in cats, ferrets, and other exotic animals?
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It causes Methemoglobinemia
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Why should we never inject Bupivacaine intravascularly?
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It can cause cardiotoxicity
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____________ are more sensitive to CNS toxicity of lidocaine than other species
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Horses
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List the techniques that we normally use for regional/local anesthesia
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Blind (traditional) Peripheral nerve stimulator guided Ultrasound guided U/S and PNS guided
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Proparacaine and tetracaine are both
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Topical anesthetic drops
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List the types of infiltration anesthesia
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Linear infiltration Filed block Continuous infiltration anesthesia
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What is a filed block?
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Linear infiltration + deposition into deeper tissues
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Continuous infiltration anesthesia
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Uncommon in vet med Fenestrated catheter + infusion pump "Pain Buster Soaker system"
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Infiltration Anesthesia: Pros
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Simple, easy, quick No anatomical knowledge required
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Infiltration Anesthesia: Cons
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High volume to inject Easier to overdose Limited area to be anesthetized Surface tissue only "Patchy" anesthetized area
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When should we consider using infiltration anesthesia
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Catheter placement Minor and localized cutaneous surgery Wound infusion catheter
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When should we not consider using infiltration anesthesia
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Major procedures Large surface area: likely becomes overdose Deeper layer
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What volume of anesthetic should we inject for Infraorbital, Mandibular, Mental, Major palatine blocks for dogs?
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0.1-1.0 ml per site
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What volume of anesthetic should we inject for Infraorbital, Mandibular, Mental, Major palatine blocks for cats?
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0.1-0.2 ml per site
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What volume of anesthetic should we inject for Infraorbital, Mandibular, Mental, Major palatine blocks for horses?
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5 ml per site
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A infraorbital nerve block is injected where?
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Infraorbital foramen
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A mandibular nerve block is injected where?
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Mandibular foramen
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A mental nerve block is injected where?
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Mental foramen
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A major palatine nerve block is injected where?
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Major palatine foramen
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Infraorbital nerve block can be use for _______________?
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Ipsilateral premolar, canine, incisor teeth and associated soft tissues, upper lip, nose
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Mandibular nerve block can be use for ______________?
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Ipsilateral molars, premolars, canine, incisors, skin, mucosa of chin, lower lip
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Mental nerve block can be use for _______________?
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Ipsilateral lower lip
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Major palatine nerve block can be use for _______________?
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Bone and soft tissue of ipsilateral hard palate
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Auriculopalpebral nerve blocks the _______________ nerve
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Facial
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When is the auriculopalpebral nerve block used
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Common in horses Useful for examination of the eye, especially one with pain Akinesia of upper eyelid +/- lower eyelid Some palpebral function remains intact
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Where is a retrobulbar block injected?
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Injection into the muscle cone of the eye
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Which nerves does the retrobulbar block?
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CN II-VI
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Where is a inferior-temporal palpebral RBB injected?
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Midway b/w lateral canthus and the middle of lower eyelid
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Splash blocks are often used after which procedure?
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After enucleation
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Are retrobulbar blocks (RBB), Inferior-temporal palpebral RBB, Splash blocks used in small animal or large animal?
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Small animal
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Is the orbital fossa approach to a retrobulbar blocks used in small animal or large animal?
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Large animal
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Four-point block: for enucleation is made at ____________ (Hint: think of the clock)
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12, 2 or 4, 6, 8 or 10 o'clock
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When doing a four-point block for enucleation why should we avoid 3 or 9 o'clock
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You risk hitting the blood supply
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Why should we be careful when doing a four-point block for enucleation at 6 o'clock
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You are close to the optic nerve To be safe, direct slightly medially
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True or False: a four-point block for enucleation creates analgesia and akinesia of the eye
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True
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Possible complications of a four-point block for enucleation
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Intrathecal injection (brainstem anesthesia): respiratory arrest Peribulbar/retrobulbar hemorrhage Globe perforation Nerve damage Pressure behind the globe: oculocardiac reflex
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If you want to block feeling to the horn and surrounding skin and ear in the cow, which block should you use?
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Cornual br. inject halfway b/w lateral canthus & the horn
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Which nerve does the cornual block block?
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Zygomaticotemporal n. Also the ophthalmic n. and trigeminal n.
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If you want to block feeling to the horn and surrounding skin and ear in the goat, which blocks should you use?
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Cornual br of zygomaticotemporal nerve (A) AND cornual br of infratrochlear nerve (B) Halfway b/w medial canthus & medial base of the horn
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Brachial plexus (C6-T1) block: Anesthetized area
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Within or distal to the elbow
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Brachial plexus (C6-T1) block: Injection site
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Medial to scapulohumeral joint, direct a needle parallel to vertebral column toward costochondral junction
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Brachial plexus (C6-T1) block: Particular complications
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Pneumothorax Phrenic nerve blockade: hemidiaphragmatic paresis Horner's syndrome (likely temporally)
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Which nerves are block with a RUMM block
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Radial, ulnar, median, musculocutaneous
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RUMM block: Injection sites
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Lateral (R) and medial (UMM) of mid-humerus
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RUMM block: Advantages over traditional BPB
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Easy to perform Less complication
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The "Declaw" block 3-point block or ring block blocks which nerves
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Radial, dorsal and palmar, ulnar, median
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Intercostal block: indications
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Great for lateral thoracotomy, chest tube placement
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Intercostal block: injection sites
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2 adjacent intercostal spaces both cranial and caudal to the incision/injury site
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Intercostal block: Complications
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Pneumonia
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What block should we use for a laparotomy (Ruminants)
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Line block: small area to be anesthetized Inverted-7 or L block
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True or False: an inverted-7 or L block provides complete analgesia
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False, provides incomplete analgesia
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Proximal paravertebral block anesthetizes which nerves
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Desensitization of T13, L1 & L2
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Proximal paravertebral block: Landmark
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L2 transverse process Perpendicular insertion at 5-10 cm lateral to the midline Cranial aspect of the transverse process of L1, L2 and L3
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Distal paravertebral block anesthetizes which nerves
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T13, L1 & L2
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Distal paravertebral block: Landmark
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L2 transverse process Horizontal insertion distal end of L1, L2 & L4 transverse processes
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Epidural (SA): Injection site
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Lumbosacral space (L7-S1)
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Which areas are desensitized by an epidural?
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Caudal abdomen Pelvis Hind limbs Perineal area *Cranial abdomen and thoracic cavity with larger volume
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Epidural: Injection site
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End of spinal cord: species-dependent og: L5-L7, cat: L6-sacrum
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Epidural: what type of needle should we use?
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Spinal needle, Tuohy needle
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Epidural: Landmarks
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Iliac wings (thumb and middle finger) L7 dorsal spinous process (index finger)
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How do you know you are in "epidural" space?
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"Pop" sensation: flavum ligament Loss of resistance: epidural space has negative pressure Hanging drop: saline meniscus Test injection of saline
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Epidural: ________________ is the major factor for how far the drug will travel cranially!!
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Volume
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Epidural: If the needle tip is in subarachnoid space, decrease the injection volume to _____________________
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1/3 or 1/4
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Epidural: what drugs do we typically use?
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Morphine Bupivacaine
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Epidural: which drug is fast onset and short duration
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Bupivacaine
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Epidural: how fast is the onset for Bupivicaine
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10-15 minutes
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Epidural: how long is the duration for Bupivicaine
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2-4 hrs
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Epidural: how long does it take for morphine to take effect?
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Up to an hour
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Epidural: how long does morphine last?
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12-24 hr
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True or false: morphine and bupivicaine can have a synergistic effect.
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True
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Epidural: side effects
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Paralysis: pelvic limbs High volume/speed can block breathing muscles!! Sympathetic block: cardiovascular collapse *Sympathetic system: thoracolumber Morphine Pruritus, urinary retention (rare)
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Epidural: contraindications
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Skin infection, neoplasia at the injection site Bleeding disorder Uncorrected hypovolemia Sepsis, bacteremia
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Caudal Epidural (LA): Injection site
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First coccygeal interspace (Co1-Co2) First obvious midline depression caudal to the sacrum Can be sacrococcygeal (S5-Co1) in ruminants
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Caudal Epidural (LA): Area to be desensitized
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Tail, perineum, anus, rectum, vulva, vagina, prepuce, skin and scrotum
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Intratesticular Block: onset in horses
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Horses: ~10 min for distribution into spermatic cord
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True or False: intratesticular blocks and spermatic Cord infiltration do not block sensation to the skin
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True
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Spermatic Cord Infiltration: Desensitization of the ___________________
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Spermatic cords and testicles
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If we want to desensitize the testicles of a sheep or goat, which block should we do? (my interpreation)
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Combination of infiltration block in the scrotum and the spermatic cords Good rule of thumb for ruminants always calculate per kg dose for local anesthetics
