Anesthesia 2

True

true

Acepromazine

Hypoglycemia

true

Fluid therapy, emergency drugs

Several minutes of 100% O2 before anesthetics increase time to hypoxia if airway is compromised

• Brachycephalic: upper airway syndrome (stenotic nares, elongated soft palate, everted saccules, redundant pharyngeal tissue, hypoplastic trachea.  Hard to visualize rima glottidis due to elongated soft palate, everted saccules and redundant pharyngeal tissue.
• cats: prone to laryngospasm, spray with lidocaine.  May not incubate in castration

Hook up to 100% O2

Apex beat or pulse

ensure ET tube is not past carina, only inflating one lung

• light: central eye position, present palpebral, jaw tone
• deep: central eye position, no palpebral, no jaw tone
• adequate: rotated eye position, no palpebral, some jaw tone

• pulse oximeter
• capnograph
• BC oscillometer or doppler
• ECG
• Thermometer

• Once coughing or swelling strongly at least twice in a short period. 
• Brachycephalic: only when chewing, gagging and/or strongly coughing.

respriatory rate and pattern.  Pulse ox on room air, take vital signs and assess pain

Pain vs emergence delirium.  Pain is ALERT and directed towards painful site.  Delirium is staring into space, not directed towards site.  If not sure, check for pain first.

• Hydrosoluble so peripheral only, no BBB
• NO SEDATION OR ANALGESIA
• muscle relaxants only - skeletal muscle, not smooth or cardiac.  PARALYSIS, cannot breathe or move in response to pain.
• Depolarizing (succinylcholine) or non-depolarizing (most, intermediate or long-acting)

• Nerve synthesizes ACh, impulse causes release into synaptic cleft, binds to nicotinic receptor on post, causes conformational change, leading to end-plate potential and muscle contraction. 
• ACh hydrolized by AChE, reduces ACh, receptor ion channels close.

• MOST
• bind to receptor to prevent interaction with ACh (competitive antagonists), so can be reversed by increasing ACh.  
• NOT hydrolyzed by AChE, so reversal depends on redistribution, metabolism, excretion (or reversal like edrophonium and neostigmine, inhibit AChE to increase ACh)
• intermediate: atracurium, vecuronium, rocuronium
• long: pancuronoium

• Edrophonium or neostigmine.  AChE inhibitors, allow ACh to build up in synaptic cleft to compete with NMBA.  
• Increases in ACh can cause CV complications so give with atropine or glycopyrrolate.
• Ceiling effect, DEEP block cannot be antagonized 
• ALSO sugammadex - SELECTIVE relaxant binding agent - binds SPECIFICALLY to rocuronium/vecuronium/pancuronium

• succinylcholine resembles ACh
• binds to receptor and generates an action potential - AGONIST
• contraction/fasciculation then paralysis, doesn't let go. Hydrolyzed in plasma by pseudocholinesterase NOT AChE, no antagonist
• Works in 30 seconds, faster than everything else.

• NECESSARY
• peripheral nerve stimulator
• Train of Four - twitch gets gradually less intense over time (fades).
• When drug wears off, all four twitches equal

• Presence of undetected weakness after anesthesia
• increases risk of aspiration, upper airway obstruction and hypoxia
• mild can't be easily detected.  Anesthetics and hypothermia also increase risks of residual paralysis

• Atracurium, cisatracurium
• can release histamine (tachycardia, hypotension, bronchospasm)
• extra-hepatic metabolism

• Vecuronium, rocuronium
• tend to be vagolytic
• hepatic metabolism
• renal excretion

• a spontaneous nonenzymatic chemical breakdown occurs at physiological pH and temperature
• how atracurium is broken down

• Hoffman elimination: a spontaneous nonenzymatic chemical breakdown occurs at physiological pH and temperature
• ester hydrolysis: by nonspecific esterases
• pharmacokinetics are independent of liver and renal function

• depress CV
• exacerbated

10 ml/kg/min

• measure of global balance between supply and demand of oxygen
• goes down when EITHER O2 demand increases or O2 supply decreases
• mixed venous oxygen content: ~15 ml/dl
• arterial oxygen content: ~20 ml/dl
• so the body uses 5mL of O2 from every 100mL of cardiac output

• oxygen delivery = cardiac output x oxygen content of arterial blood
• DO2 = Q x CO2
• Cardiac Output = Q = stroke volume x heart rate

oxygen on hemoglobin + oxygen in simple solution

• sigmoid curve designed to pick up large volume of oxygen in lung and unload it in tissues with a small drop in PaO2
• very little PO2 in plasma (linear relationship, not sigmoid).  Breathing 100% O2 increases by a TON, to become ~30% of body's needs, so this helps anemic patients a LOT

• Ohm's Law for DC current
• current = voltage/resistance
• cardiac output = pressure drop / vascular resistance (so CO proportional to systmeic arterial pressure unless there are vasoconstrictors)

• High myocardial O2 demand
• often restricted outflow tract (high resistance to flow around aortic valve
• poor pump function
• increasing HR doesn't allow time for ventricular filling

• big globular heart on radiographs
• pericardium full of exudate/transudate (no compliance)
• ventricles can't fill
• atria can't "kick"
• stroke volume low
• aspirate the pericardial sac!

• ~14/min
• 10-15 mL/kg
• Vd/Vt ~ 60%, more than HALF is dead space!
• enough pressure on inspiration to collapse airways or cause pulmonary edema, so lungs collapse under anesthesia due to position and lack of tone, and reopening is hard
• V/Q mismatch more common in horses than others

• HR 30-45
• ABP 130/90 (100)
• MAP <70 causes rhabdomyolysis
• I-II AV blocks are common, AF most common arrhythmia
• anesthetics cause hypotension due to vasodilation and poor contractility

• 14g catheter in L jug
• rinse mouth - they pack like chipmunks
• >12h fasting to increase functional residual capacity and decreases tympanism (otherwise they FERMENT under anesthesia and bloat, can't breathe
• careful if using K-Pen as abx, K too fast causes bradycardia and hypotension

• alpha-2: xylazine (least specific), detomidine, romifidine, dexmedetomidine (most specific).  CV effects less severe than dogs/cats, so most common sedatives for equine.  Stay standing.
• phenothiazines: acepromazine, ataxia but stay up, alpha-1 blockade may cause hypotension, non-reversible, priaprism
• Benzodiazepines: diazepam, midazolam, not great sedatives and can cause excitation, good in neonates or with ketamine. 
• opioids: combined to augment sedation, but constipation.  Morphine good analgesic but colic/excitation.  Torb is shorter and more mild, but fewer effects
• USE XYLAZINE

• IV always through catheter!  Can mask but only really for foals or research
• Dissociatives: ketamine, usu with benzos.  "slow", CV stability, moderate resp depressino, analgesia, but causes muscle rigidity
• Inhalational: Iso most common, more hypotension than dog/cat.  Usu add something to decrease MAC (ketamine, lidocaine, detomidine)
• often SEVERE hypoventilation and lots of atelectasis so we use IPPV

• guaifenesin (sometimes midaz), ketamine and xylazine
• enough for short, not-complex procedures, used in field conditions

• ruminant DA, C-section etc
• block down T13/L1, across top to L4 
• Takes a while to work and peritoneum may not get enough at first?
• Lidocaine usually, SQ tunnel then three layers

• rumenotomy, DA, C-section
• Proximal paravertebral nerve block: just lateral to vertebral dorsal spinous processes of T13, L1, L2
• Distal paravertebral block: Dorsal and ventral to lateral vertebral processes

• for amputation of a digit, don't use a ring block
• tourniquet then inject into radial vein, palmar metacarpal vein and/or dorsal metacarpal vein, lateral saphenous for hind.

midway between canthus of eye and horn, gets auriculopalpebral and cornual branch of the zygomaticotemporal.  May also put some in medial canthus of eye (infraorbital)

• DILUTE LIDOCAINE, more sensitive (doesn't last as long), get twitchy and neurological
• inject midway between lateral canthus and ear (zygomaticotemporal) PLUS infratrochlear

• peri- and intra-vaginal procedures
• between 1st and 2nd coccigeal vertebrae with Tuohy needle

• lumbosacral space
• In goats, spinal cord can extend longer so be careful

• ring block
• testicles: line block under skin and rest into testes

• xylazine: most common in cattle - more sensitive than horses.  Sheep more than cattle, goats more than sheep.  SHEEP - pulmonary edema and hypoxemia, increased diffusion limitation
• benzodiazepines: midaz/diaz with induction agents, can be used with butorphanol for sedation.  OFTEN with torb in sheep

• serious complications, so fast adult cattle 18-24h, water 6-8h.
• fast small ruminants 6-12h, off water 2-3 hours
• neonates miss one feed, they're essentially monogastric
• don't use parasympatholytics, make saliva viscous

• cast with casting rope first
• IV induction with ketamine (usu + diazepam), propofol ($$$), guaiafenesin
• intubate cow with gag and arm, physically palpate larynx.  Small ruminants ET like dogs but LONG laryngoscope blade. 
• Wash out mouth before extubation because they DID regurg

• spasm when you remove the tube, you have to just re-anesthetize and re-tube
• Stop breathing sometimes.  
• Hard to get catheter in jug because of thick skin, no good veins in limbs.

no handles, can't get at veins for injection, screaming!  Weird trachea hard to work with, blind diverticulum in larynx, oval cricoid very narrow, malignant hyperthermia

• oral diazepam in palatable vehicle
• can use acepromazine or azaperone

• injectable anesthetics IM
• Telazole: low volume and high therapeutic index, but very long recovery
• Alpha2 + ketamine + opiate: most reliable
• use these as chemical restraint then put a catheter in the ear vein, top with ketamine or propofol

• Rare, genetic, mostly bred out
• first sign is front legs extending and claws separating.  
• Temperature increases, resp rate increases, struggle, lactic acidosis, arrhythmias and death
• discuss with owner FIRST

Maintain homeostasis,airwayandanalgesia

understandphysiology and pathophysiology

• increased abdominal return: decreases venous return, reduces FRC (pressure on aorta and VC, weight doesn't let chest expand), increases risk of hypoxia
• dilutional anemia
• risk of hemorrhage (hyperperfused uterus)
• progesterone decreases MAC (easier to OD)
• lowers vascular resistance (prone to hypotension - progesterone increases to make it easier to perfuse uterus)

• Mannitol to draw fluid from cranium, decrease ICP
• ICP increased by: vomiting, coughing, increased CVP, hypercarbia, hypoxemia, inhalational anesthetics, ketamine, severe hypertension
• swings in BP cause swings in ICP
• maintain MAP over 80mmHg (phenylephrine) to ensure blood can GET into cranium against pressure

• secondary to ICP, arterial BP increases then reflex bradycardia.  Sudden hypertension and bradycardia in surgery means ICP IS INCREASING
• Pressure that goes into brain depends on MAP and ICP, so keep MAP high

• Hyperglycemia: increases density of blood (thicker), diuretic causing PUPD, both can cause dehydration
• iatrogenic hypoglycemia: too much insulin without eating.  NO symptoms show under anesthesia
• SLOW gastric emptying time: increases risk of regurgitation and aspiration
• cardiac autonomic neuropathy: may not respond/compensate as well
• potential renal disease: long-term diabetes due to hyperglycemia = tubular necrosis
• DKA: no insulin = no glucose = fat for energy = ketones = acidosis
• FASTING: early sx, fast overnight.  Late, feed a wet meal with motilin in the morning.  Measure and decide on insulin.  
• Repeated BG and acid-base monitoring throughout sx.

• painful!  
• Peritoneal fluid = compression = hypoxia
• vomiting = aspiration, acid/base
• vasodilation!  So decreased renal perfusion and dehydration/hypovolemia
• sedation/pain control without emesis (opioids, supplement with O2), quick induction to prevent aspiration, low MAC or TIVA to minimize vasodilation
• optimize pre-surgery

method of inducing and maintaining general anesthesia exclusively by intravenously administered drugs

• pros: superior recovery profile, portable delivery system, less OR pollution
• cons: expensive, best drugs/delivery systems not always available, no reliable technique for monitoring plasma concentration

there isn't one

new method of TIVA administration, aims for a target blood concentration - does the math for you, starts with higher dose and titrates down.  Doesn't MEASURE, just based on math.

• propofol (NO repeated 3 days in cats or heinz body anemia, maybe motor activity in dogs?)
• fentanyl
• dexmedetomidine
• detomidine-guaiphenein-ketamine

true

Decreases rate of dissociation of GABA from GABA-A receptors

Rapid redistribution to other tissues like fat and rapid metabolism (liver, lungs)

Decreases cerebral metabolic rate for O2, cerebral blood flow and intracranial pressure

Decreased myocardial contractility and vasodilation = hypotension, blunts baroreceptor reflex

true

decrease

Oxidative injury to RBC = Heinz body anemia

NMDA

True - ketamine

Excreted unchanged by kidneys mostly

Seizures, increased cerebral blood flow and intracranial pressure, emergence delirium/hallucinations

Indirect CV stimulation, direct myocardial depression

Don't depress ventilation as much as protocol, bronchodilator, pharyngeal/laryngeal reflexes maintained

Enhances affinity of GABA for GABA-A (no analgesic)

Hydrolysis by hepatic microsomes like enzymes and plasma set erases, excreted in urine and bile

• IV induction of general anesthesia
• especially good for CV patients (also renal, hepatic, hypovolemic)

True

Adrenocortical suppression

Alfaxalone

Enhances GABA-mediated neurodepression (like propofol, etomidate, etc)

Hepatic glucuronidation, then kidney

False, slower

true

Decrease dissociation of GABA and open Cl- channel.  No analgesic

False, decrease

• CV: vasodilation, myocardial depression, arrhythmias
• Resp: dose-dependent depression

Tissue sloughing

• Minimally metabolized so decrease liver burden, don't have to inject
• no rapid control of airway, stressful, excitement phase if not premed, can vomit/regurgitate and we don't have airway control

Moribund (extreme CV stability)

no, possibly a short fast for a GI surgery, etc.  Fasting could be detrimental in some species (rabbits, guinea pigs)

true - rabbits, guinea pigs

true

FALSE, dehydration and hypoglycemia

true

true

• ferrets: scruffing, wrapping in towel, muzzle
• rabbits: scruffing, wrapping in towel, restrain pelvic limbs to prevent vertebral column fracture
• rodents: scruffing, cupping in hands, tapered plastic film tubes with breathing hole, purpose-build restrainers

true, cranial vena cava

superficial temporal vein and retroorbital venous plexus

atropinases

nonrebreathing

• epiglottis dorsal to soft palate
• mouth doesn't open widely
• larynx caudal and ventral to angle of mandible
• butterfly-shaped epiglottis

• blind while listening for airflow and looking for condensation
• blind with capnograph
• visual with or without guide tube
• retrograde
• nasotracheal

palatal ostium (fusion of soft palate to base of tongue)

• otoscope and guide tube
• fiberoptic endoscope

V-gel (laryngeal cup)

buprenorphine

porphyrin

• reduced activity
• altered posture or gait
• arched back, short stride
• decreased urination and defecation
• hide in corners
• reduced grooming
• porphyrin staining
• change in temperment
• vocalizations
• reduced eating/drinking and weight loss/dehydration
• increase in HR, change in RR, shock

• may have no history, PE, diagnostics
• few protocols for many species
• stressful induction
• environmental hazards
• difficult to provide supportive care and monitoring
• limited knowledge of physiology and pharmacology

• physical trauma
• zoonotic disease
• danger from other animals in area/herd
• immobilization drugs
• capture technique (helicopters)
• environmental hazards

• communicate
• understand the target species
• be familiar with your environment
• know location of emergency medical services
• wear PPE
• handle drugs carefully and with a buddy
• have antagonists available
• only experienced people should handle delivery equipment

• time of year and day
• weather/climate
• terrain
• equipment
• capture technique (physical, chemical, both)
• target vs non-target animals

• rapid onset
• high margin of safety
• handler safety
• small volume
• produces hypnosis
• reversibility
• versatility
• stability

41 (=105.8F)

• avoid capture in hot ambient temps, avoid stress or prolonged pursuit, minimize physical restraint, protect from sun
• aggressive cooling, pharmacological antagonism, oxygen supplementation

• position in sternal recumbancy with neck extended or elevate cranial end of body
• pass orogastric tube
• trocarize (sterile!)
• pharmacological antagonism

exertional rhabdomyolysis

ungulates

sympathetic nervous system

true