Locoregional - VetPrep.pdf

Locoregional anesthesia techniques for large animals Dr. André Escobar, DVM, Ms, PhD, DACVAA Assistant Professor of Anesthesiology Equine eye – motor nerve Auriculopalpebral nerve block Used to prevent closure of the eyelid (blinking) Ophthalmic exam Nerve can be palpated Motor block only – do not d...

Locoregional anesthesia techniques for large animals Dr. André Escobar, DVM, Ms, PhD, DACVAA Assistant Professor of Anesthesiology Equine eye – motor nerve Auriculopalpebral nerve block Used to prevent closure of the eyelid (blinking) Ophthalmic exam Nerve can be palpated Motor block only – do not desensitize the eye Injection site Dorsal aspect of the zygomatic arch OR Depression caudal to the mandible Lumb and Jones 2015 Equine eye – sensory nerves A - Supraorbital nerve Majority of the upper eyelid Injection at supraorbital foramen B - Lacrimal nerve C – Infratrochlear nerve D – Zygomatic nerve SQ injection Standing enucleation All nerves previously mention + retrobulbar Lumb and Jones 2015 Equine dental Infraorbital nerve block Desensitize ipsilateral upper lip and nose (G) Desensitize teeth rostral to 1st molar, maxillary sinus, roof of nasal cavity (H) Mental nerve block Desensitize lower lip (I) Desensitize lower incisors (K) Lumb and Jones 2015 Equine dental Inferior alveolar nerve block Anesthesia of the mandible https://academyofequinedentistry.wordpress.com Equine dental Maxillary nerve block Maxilla and sinus cavity https://academyofequinedentistry.wordpress.com Equine epidural Caudal epidural Prevent loss of motor function Inserted between Co1-Co2 space Space palpated moving the tail up and down Loss of resistance/ hanging drop technique Equine epidural Indications Tail, perineum, rectum or vulva procedures Fetotomy, obstetric manipulations Hindlimb analgesia (do not use local anesthetics) Equine epidural - drugs Morphine Provides analgesia No risk of weakness or motor blockade Hind limb trauma, surgery, severe laminitis Side effects: urticaria, ileus Often administered through epidural catheter for longer- term (days) analgesia Equine epidural Epidural catheter Inserted between Co1-Co2 space Do not use local anesthetics – motor block Analgesia for multiple days If advanced to LS space – analgesia for hind limbs Alpha-2 agonist + morphine – excellent analgesia Duque 2007 Intratesticular block Anesthesia for castration Horses, ruminants, swine Under GA or sedation Lidocaine volume Horses – 20 mL Small ruminants 2-5 mL Quickly diffuses into the spermatic cord Lumb and Jones 2015 Ruminant eye Retrobulbar block (A) – enucleation Auriculopalpebral block (B) – examination of the eye Ruminant dehorning Cattle Cornual branch of zygomaticotemporal nerve (D) Very painful procedure specially in adults Ruminant dehorning Goats Cornual branch of zygomaticotemporal nerve (1) Cornual branch of infratrochlear nerve (2) A ring block around the horn is commonly performed Lumb and Jones 2015 Ruminant flank laparotomy Line block (infiltration) Block SQ and muscular layers LA injected along the incision line Inverted L block (infiltration) Injection remote from incision site Caudal aspect of the last rib Ventral aspect of the lumbar vertebrae transverse processes Ruminant flank laparotomy Proximal paravertebral block Dorsal and ventral branches of T13, L1 and L2/ inclusion of L3 provides better anesthesia Injection site 3-5 cm from dorsal midline, majority of drug deposited at VENTRAL aspect Signs of blockage: Spinal scoliosis Increased skin temperature Absent reaction to pinprick Lumb and Jones 2015 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 Majority of drug injected ventral to process Lumb and Jones 2015 Ruminant caudal epidural Indications: obstetric manipulations and surgical procedures for tail, perineum, anus, rectum, vulva, vagina, prepuce, scrotum Commonly and easily performed Injection between S5-Co1 or Co1-Co2 space (A) Drugs: local anesthetics, alpha-2 agonists, morphine Lumb and Jones 2015 Ruminant lumbosacral epidural Used in immature cattle, small ruminants, camelids, and pigs (caudal epidural preferred for adult cattle) Will induce loss of motor function Injection between L6-S1 Similar technique as for dogs Lumb and Jones 2015 Anesthesia of the teats To treat teat lacerations, remove polyps, others Techniques Ring block (A) Inject distal to the tourniquet Inverted 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 distal to the tourniquet Lumb and Jones 2015 Anesthesia of the udder Paravertebral block of L1- L3 (1-4) Cranial aspect of udder and teats Pudendal block (5) Caudal aspect of teats and udder Lumb and Jones 2015 Intravenous regional anesthesia (“Bier block”) Foot is a common site of injury or disease Similar than small animals