Locoregional anesthesia (struc) Flashcards
Equine eye – motor nerve
- ? nerve block
- Used to prevent ? of the eyelid (blinking)
- Ophthalmic exam
- Nerve can be palpated or not palpated?
- Motor block only? – do not desensitize the eye
- Injection site
- Dorsal aspect of the ? arch OR -
- Depression caudal to the ?
Equine eye – motor nerve
- Auricolupalpebral nerve block
- Used to prevent closing of the eyelid (blinking)
- Ophthalmic exam
- Nerve can be palpated!
- Motor block only – do not desensitize the eye (so only prevents closing of the eyelids and if procedure done then horse WILL FEEL IT! as its only motor block and not sensory)
- Injection site
- Dorsal aspect of the zygomatic arch (Dr. Escobar prefers this one)
OR - Depression caudal to the mandible
Equine eye – sensory nerves
(refer to pic)
* A - ? nerve
- Majority of the ? eyelid
- Injection at ? ?
* B - ? nerve
* C – ? nerve SQ injection
* D – ? nerve
(among A, B, C and D which ones are associated w SQ injection?
- For standing enucleation, the following nerves will have to be blocked:
- All nerves previously mention which are 1. auricolopalpebral nerve 2. the four nerves above and 3. retrobulbar (nerves innervating the eyeball and present on back of eye)
(for the 4 nerves will do ? block, a fiiltration block around eye in subcut tissue not separately and just doing ring block which blocks all 4 nerves A, B, C, D; much safer to PERFORM SURGICAL PROCEDURE ON HORSE while its standing!! on small animals it works better, in horses when the anesthesia wears off they can fracture their legs etc.)
Equine eye – sensory nerves
(refer to pic)
* A - supraorbital nerve
- Majority of the upper eyelid
- Injection at supraorbital foramen
* B - lacrimal nerve
* C – infratrochlear nerve (SQ injection)
* D – zygomatic nerve
(among A, B, C and D which ones are associated w SQ injection? B, C and D
- For standing enucleation, the following nerves will have to be blocked:
- All nerves previously mention which are 1. auricolopalpebral nerve 2. the four nerves above and 3. retrobulbar (nerves innervating the eyeball and present on back of eye)
(for the 4 nerves will do RING block, a fiiltration block around eye in subcut tissue not separately and just doing ring block which blocks all 4 nerves A, B, C, D; much safer to PERFORM SURGICAL PROCEDURE ON HORSE while its standing!! in small animals it works better, in horses when the anesthesia wears off they can fracture their legs and much more unsafer etc.)
Equine dental
* Infraorbital nerve block
- Desensitize ipsilateral (so only one side) upper or lower? lip and ? (G)
- Desensitize teeth rostral to #st? ?, ? sinus, roof of ? cavity (H)
- Mental nerve block
- Desensitize lower or upper? lip (I)
- Desensitize only lower or upper? incisors or canines? (K)
Equine dental
* Infraorbital nerve block
- Desensitize ipsilateral (so only one side) upper lip and nose (G - refer to pics which show where exactly the injections are put into)
- Desensitize teeth rostral to 1st molar teeth, maxillary sinus, roof of nasal cavity (H)
- Mental nerve block
- Desensitize lower lip (I)
- Desensitize only lower incisors (K)
note: injecting given vertically associated with lip
and horizontal with teeth
Equine dental
- Inferior alveolar nerve block (and not “mandibular nerve!)
- Anesthesia of the ?
(if just incisors then use mental nerve).
Equine dental
* ? nerve block
- ? and ? cavity
Equine dental
- Inferior alveolar nerve block (and not “mandibular nerve!)
- Anesthesia of the mandible
(if just incisors then use mental nerve; EVEN dental is performed on horses standing).
Equine epidural
Caudal epidural
* Prevent loss of ? function
- Inserted between Co#?-Co#?
- Space palpated moving the tail up and down
- ? of resistance/ ? technique
( - cerebrospinal fluid present between pia mater and arachnoid membrane (gray area) &
- epidural space present in the brown space between the spinal canal (yellow ligament part of this) and dura mater;
so if u go v deep then will end up in subarachnoid space and extract cerebrospinal fluid which can be DISASTROUS for horses
in small animals, we don’t do this and use a lumbosacral epidural between L7 and S1;
- if u inject local anesthesia there then motor nerve paralysis and can’t move hind legs or anything caudal to the umbilicus, if done on horses then they go crazy and might try to kill themselves hence we do CAUDAL EPIDURAL on them
- when introducing a needle we feel a pop at the yellow ligament when trying to get epidural
- if needle still not there then put a drop of local anesthetic or ceiling in the hub of the needle and once in epidural space it, the local anesthetic will be aspirated bc of negative pressure - HOW U CONFIRM UR IN EPIDURAL SPACE; another way is “hanging drop technique”)
Equine epidural
Caudal epidural
* Prevent loss of motor function
- Inserted between Co1-Co2 (Co= coxygeal, no spine here) space (by moving tail up and down and using fingers to find space between the spinal process of the coxygeal vertebrae, then find larger space and introduce needle)
- Space palpated moving the tail up and down
- loss of resistance/ hanging drop technique
(hanging drop technique: basically there’s some syringes that come in the epidural catheter kits in which plunger has no resistance, so you just try to inject one metal of air into the epidural space after you feel that pop.
If there is resistance to the injection of air, you’re in the muscle. If there’s no resistance, if you’re in the epidural space!)
( - cerebrospinal fluid present between pia mater and arachnoid membrane (gray area) &
- epidural space present in the brown space between the spinal canal (yellow ligament part of this) and dura mater;
so if u go v deep then will end up in subarachnoid space and extract cerebrospinal fluid which can be DISASTROUS for horses
in small animals, we don’t do this and use a lumbosacral epidural between L7 and S1;
- if u inject local anesthesia there then motor nerve paralysis and can’t move hind legs or anything caudal to the umbilicus, if done on horses then they go crazy and might try to kill themselves hence we do CAUDAL EPIDURAL on them
- when introducing a needle we feel a pop at the yellow ligament when trying to get epidural
- if needle still not there then put a drop of local anesthetic or saline? in the hub of the needle and once in epidural space it, the local anesthetic will be aspirated bc of negative pressure - HOW U CONFIRM UR IN EPIDURAL SPACE; another way is “hanging drop technique”)
Equine epidural
Indications
* Tail, perineum, rectum or vulva procedures (2nd pic shows the area in which it is done which is the tail, peri..)
* Fetotomy, obstetric manipulations
* Hindlimb analgesia (do not use ? anesthetics)
(- in 1st pic, got too much lidocaine and fell on the floor, so avoid high amount which would reach L3 and 4 which are innervating hindlegs
- We can also use an epidural for a hind limb analgesia, so we can use an analgesic drug that doesn’t cause anesthesia; Anesthesia would be loss of motor function, loss of sensation, such as touching the skin, and not feel anything
- thus anesthesia causes loss of pain AND motor and sensory function
ANALGESIA (not anesthetic) just increases the threshold of pain; for this we can use a higher volume and we can even use an epidural catheter that I’m going to talk the next slide;
- Morphine, an analgesic, can last for 24 hrs if given in epidural space and it provides analgesia in the 4 limbs even if given only in tail; Morphine is so hydro soluble that dilutes in the CSF and pretty quickly diffuses to the cranial part of the body.)
Equine epidural
Indications
* Tail, perineum, rectum or vulva procedures (2nd pic shows the area in which it is done)
* Fetotomy, obstetric manipulations
* Hindlimb analgesia (do not use local anesthetics)
Equine epidural - drugs
Local anesthetics
* Volume important to limit ? spread of anesthetic
- Must avoid hind limb ? (motor blockage)
- Lidocaine #?% (6-8mL) in an adult horse is adequate for anus, ?, rectum, ?, vagina, ?, bladder
Alpha-2 agonists
* ?, ? (common)
* Causes local ? and systemic alpha-2 effects (sedation, 2nd degree AV block, ataxia, etc)
* Side effects can be reversed with IV ?
Equine epidural - drugs
Local anesthetics
* Volume important to limit cranial spread of anesthetic (to avoid horses falling down e.g. horses not able to stand upright due to high amount of lidocaine (2% lidocaine, more than that cause ataxia, loss of motor function) that went into L3 and 4 which innervates hindlimbs)
- Must avoid hind limb ataxia (motor blockage)
- Lidocaine 2% (6-8mL) in an adult horse is adequate for anus, perineum, rectum, vulva, vagina, urethra, bladder
Alpha-2 agonists
* xylazine, detomidine (common)
* Causes local analgesia and systemic alpha-2 effects (sedation, 2nd degree AV block, ataxia, etc)
* Side effects can be reversed with IV antagonist
(only until L7 and until S3 in dogs
whereas L6 and S5 in horse and small ruminants (pic shows needle going in between L6 and S1
- not going to do the needle thing between L6 and S1 as seen in pic in adult horses and cows and ONLY in small ruminants so if they lose control in hindlimbs we can control that but NOT in adult animals
- the needles on the right show the caudal epidural between 1st and 2nd coxygeal vertebrae )
Equine epidural - drugs
Morphine
* Provides ?
* No risk of ? or ? blockade
* Hind limb trauma, surgery, severe ?
* Side effects: urticaria, ileus
* Often administered through epidural ? for longer- term (days) analgesia
Equine epidural - drugs
Morphine
* Provides analgesia
* No risk of ataxia or motor blockade
* Hind limb trauma, surgery, severe laminitis - only morphine epidural can be given just for analgesia, even if it’s thoracic limbs, you can provide analgesia for thoracic limbs with morphine too!
- Side effects: urticaria, ileus (decrease in GI activity) - these are common w IV route
- Often administered through epidural catheter for longer-term
(several days) analgesia (- if giving only morphine, poking epidural space can cause fibrosis, pain, inflammation etc.)
(only morphine can be given for analgesia; more side effects observed when given through IV and lesser when injecting into epidural space
- when placing an epidural catheter, you can place the tip of the or the tip of the catheter a little bit more cranial, helps with the cranial spread of the drug
- in the case of morphine, only!
you can give lidocaine with an epidural catheter.)
Equine epidural
- Epidural catheter
- Inserted between Co#?-Co#? (coxygeal) space
- Do not use ? anesthetics which can cause ? block
- Analgesia through catheter lasts for ? days
- If advanced to LS space – analgesia for hind limbs (if want the hindlimbs L3 and 4, then can place needle lil more cranially)
- ? + morphine – excellent analgesia
Equine epidural
- Epidural catheter
- Inserted between Co#1-Co#2 (coxygeal) space
- Do not use local anesthetics which can cause motor block
- Analgesia for multiple days
- If advanced to LS space – analgesia for hind limbs
- alpha 2 agonist (can cause ataxia tho) + morphine – excellent analgesia
- Dr. Escobar would only stick to morphine tho cuz of ataxia
- need goes in and comes out laterally and not in front; so first putting needle in which is blunt in the front and then put catheter, catheter leaves through the lateral part of needle and then needle is taken out
- can use loss of resistance technique to ensure in epidural space
- SUTURE and BANDAGE the site as u don’t want ‘em to remove it from their back.
Intratesticular block
Anesthesia for castration
* Horses, ruminants, swine
Under GA or sedation
Lidocaine volume
* Horses – #? mL
* Small ruminants #? mL
Quickly diffuses into the spermatic cord
Intratesticular block
Anesthesia for castration
* horses, ruminants, swine
Under GA or sedation
Lidocaine volume
* Horses – 20 mL
* Small ruminants 2-5 mL
(rsn why lidocaine is preferred against others are due to its rapid effect, other could take 20 mins)
Quickly diffuses into the spermatic cord
(if animal not under general anesthesia and just sedation then you also have to perform an infiltration block on the skin here (pic) Because they’re going to have to cut the skin first and then remove the tactical.
- in this case giving local anesthesia intratesticular-ly but the local anesthetic will diffuse dorsally to this spermatic cord, so we ligate the spermatic cord and the anesthetic will diffuse the spermatic cord)
Ruminant eye
- ? block (A): enucleation
- ? block (B): examination of the eye
Ruminant eye
- retrobulbar block (A): enucleation
- auriculopalpebral block (B): examination of the eye
(retrobulbar: bend the needle so it goes around the eye of patient but the risk of perforating the eye globe so only perform this nerve block ONLY if removing the eye and not for e.g. cataract Sx
for ruminants, we will perform the auriculopalpebral block, just as in horses the retrobulbar nerve and all those other 4 nerves,
Going to see those two needles, they’re going around the eye here, so just an infiltration block for the supraorbital zygomatic, infratrochlear nerve and lacrimal nerves)
Ruminant dehorning
Cattle
* Cornual branch of ?-? nerve (D)
* Very ? procedure especially in adults
Ruminant dehorning
Cattle
* Cornual branch of zygomatico-temporal nerve (D)
* Very painful procedure especially in adults
(The midpoint between the lateral (near the horn) of the eye here and the horn, feel a depression into which the injection will be given
painful to remove horn! so in addition to blocking the nerve, I perform a “ring block” around the horn
So it’s just a subcutaneous infiltration around the horn just to make sure if I didn’t block the nerve properly, I’m providing enough anesthesia)
Ruminant dehorning
Goats (have 2 nerves instead of 1)
* Cornual branch of ? nerve (1)
* Cornual branch of ? nerve (2)
- ALWAYS have to perform a ? block around the horn (commonly performed)
(can’t block nerve #1 or #2? thus need to perform a ?)
Ruminant dehorning
Goats (have 2 nerves instead of 1)
* Cornual branch of zygomaticotemporal nerve (1)
* Cornual branch of infratrochlear nerve (2)
- ALWAYS have to perform a **ring block around the horn (commonly performed)
(impossible to block (infratrochlear nerve) #2, thus need to perform a RING BLOCK)
Ruminant flank laparotomy
2 ways to perform a block of the flank wall (See ans. for more elaboration)
Line block (infiltration)
* Block SQ and ? layers
* LA injected along the ? line
Inverted L block (infiltration)
* Injection ? from the incision site
* ? aspect of the last rib
* ? aspect of the lumbar vertebrae transverse processes
(refer to pic in answer for more info.)
Ruminant flank laparotomy
(- most of the time we perform laparotomy with the animals standing)
- if the horse has colic we put them under general anesthesia and we put horse on the table and we open the abdomen, for a ruminant MOST ANIMALS SURGERY DONE STANDING!!
- thus incision site (in pic: close to top L2) is going to be in the flank
- T13, L1 & L2 those are the nerves that will innervate flank wall so u need to block those nerves!
- L3 and 4 innervating the hind legs as seen in pic! so don’t block those as then cow will fall down)
2 ways to perform a block of the flank wall
Line block (infiltration)
* Block SQ and muscular layers
* LA injected along the incision line
(a knee filtration of my local anesthetic in the subcutaneous tissue in the side of the in the side of the incision i.e., line near top L2
And I’m going to block the muscles. There are three muscles there. So introduce the needle a little bit deeper and block the muscles in the incision site - easy way.)
Inverted L block (infiltration)
* Injection remote/away from the incision site
* caudal aspect of the last rib (see pic)
* ventral aspect of the lumbar vertebrae transverse processes
(inverted L here in the picture? So it’s basically another infiltration block, but a way of the incision site.
So it’s BETTER for the surgeons. There’s not going to be like that tissue that looks like edema, but is actually local anesthetic.
When the surgeons cutting the incision site, they’re going to have a clean incision site because they’re blocking away from from that site.
THUS when doing inverted L block, u don’t allow T13, L1 and L2 to reach incision site!
will have to poke the skin multiple times, smaller needle better as big needles going in w/o anesthesia would hurt!)
Ruminant flank laparotomy
Proximal paravertebral (para: adjacent to) block
* Dorsal and ventral branches of T13, L1 and L2/ inclusion of L? provides better
anesthesia
- Injection site 3-5 cm from dorsal ?, majority of drug deposited at DORSAL or VENTRAL? aspect
Signs of blockage:
* ?
* ? skin temperature
* Absent reaction to ?
(how we’re going to block them, we’re going to introduce the needle between the transverse process of T13 and L1
L1 L2, l2 L3, L3 L4
So we’re basically introducing the needle between those transverse process to block those nerves)
blanks:
L3
from dorsal midline; drug deposited at ventral aspect
signs of blockage
- spinal scoliosis
(if the left side is downwards and the right side same then the side blocked would be “r”ight side as right side would be “r”elaxed and the left side’s muscle would be contracted) - Increased skin temperature (will cause vasodilation, touch the area and feel that temp. is increased
- Absent reaction to pin-prick
Ruminant flank laparotomy
Distal paravertebral block
* Dorsal and ventral branches of T13, L1 and L?
* Dorsal and ? to transverse processes of L1, L2, and L?
* Majority of drug injected dorsal or ventral to process?
Ruminant flank laparotomy
Distal paravertebral block
* Dorsal and ventral branches of T13, L1 and L2
* Dorsal and ventral to transverse processes of L1, L2, and L4 (NOT L3!!) - as the nerve of L2 passes through L3 and in L3, L2’s nerve is away from the dorsal and ventral part of L3’s TRANSVERSE process (needs to be at transverse process to be blocked?) however in L4, L2’s nerve is lateralized meaning it is present on the d. and v. of its TRANSVERSE process)
- Majority of drug injected ventral to process
Ruminant caudal epidural
- Indications: obstetric manipulations and surgical procedures for ?, perineum, anus, rectum, ?, vagina, ?, scrotum
- Commonly and easily performed
- Injection between S#?-Co#? or Co#?-Co#? space (A)
- Drugs: local ?, ?, ?
Ruminant caudal epidural
- Indications: obstetric manipulations and surgical procedures for tail, perineum, anus, rectum, vulva, vagina, prepuce, and scrotum (- kinda the same as others as its caudal epidural, recall that picture showing the same site - near rear end)
- Commonly and easily performed
- Injection between S5-Co1 or Co1-Co2 space (A)
- Drugs: local anesthetics, alpha-2 agonists, morphine
(picture: this is just a picture of what I was talking about, moving the tail up and down with your index finger, trying to find the position;
Once you introduce your needle through the skin you can put the drop of the local anesthetic here in the hub of the needle and keep introducing your needle until you feel that pop.
The local anesthetic is aspirated so that to the epidural space and you can connect your strange aspirate.
Make sure you’re not in a blood vessel and inject very slowly over a minute or two your local anesthetic.)
Anesthesia of the teats
To treat teat ?, remove ?, others
Techniques
* ? block (A)
Inject distal to the ?
- Inverted letter? block (B)
Inject distal or proxial? to the tourniquet - Teat cistern infusion (C)
Anesthesia of the ? membranes - ? regional anesthesia of the teat (D)
Inject lidocaine IV distal to the tourniquet (a device for stopping the flow of blood like a tight bandage)
(If I place a tourniquet in my leg, in my arm and inject my local anesthetic, I.V., everything distal to the tournequet wound anesthetize including bone.)
laceration = deep cut
Anesthesia of the teats
To treat teat lacerations, remove polyps, others
Techniques
* RING block (A)
Inject distal to the tournequet
- Inverted letter V block (B)
Inject distal to the tourniquet - Teat cistern infusion (C)
Anesthesia of the mucous membranes - IV regional anesthesia of the teat (D)
Inject lidocaine IV distal to the tourniquet (a device for stopping the flow of blood like a tight bandage)
Anesthesia of the UDDER (dictionary: the mammary gland of female cattle, sheep, goats, horses, and related animals, having two or more teats (nipple) and hanging between the hind legs of the animal)
Paravertebral block of L#?- L#? (1-4)
* cranial or caudal? aspect of udder and teats
Pudendal block (5) (done around the anus of animals; will not be discussed in this class
* cranial or caudal? aspect of teats and udder
Paravertebral block of L1- L3 (1-4)
* cranial aspect of udder and teats
Pudendal block (5) (done around the anus of animals; will not be discussed in this class
* caudal aspect of teats and udder
Intravenous regional anesthesia (“Bier block”)
- ? is a common site of injury or disease
- Similar than small animals
(what is the most amount of time you should leave the tourniquet on for?)
Intravenous regional anesthesia (“Bier block”)
- foot is a common site of injury or disease - like foot abscess
- Similar than small animals
online: The Bier block for distal limb analgesia is worthy of note. In this method, a tight tourniquet is placed above the carpus or hock, if possible, after expelling blood distally by use of an Esmarch’s bandage. Then local anesthetic, usually lidocaine, is injected into any vein that can be found distal to the tourniquet.
(what is the most amount of time you should leave the tourniquet on for = Dr. Escobar: 40 mins (as it hurts more than that; literature = 90 mins; can also use a blood pressure cuff instead of the tourniquet in pic)
You’re going to get a blood vessel and inject a local anesthetic I.V. And especially for abscesses, an abscess.
Even if you perform an infiltration block all around, you’re not going to be able to block because of the inflammation.
So that’s actually a very efficient way to block everything that is distant from the tourniquet, including the abscess, because if you try to inject again,
infiltrate the abscess, it’s not going to do anything because of the inflammation
So that’s that’s very much used in ruminants, but it can also be used in dogs and other species.)
