24. Anesthesia and analgesia - USE THIS

What does Compressed Gas Association do?

Safe practice recommendations for storage & use

The manufacture of compressed gases, cylinders, and associated delivery systems are regulated by government agencies. Compressed Gas Association in the US/Canada and the European Industrial Gas Association cooperate closely with national authorities to set a manufacturing and safety standards.

Medical gases are treated as drugs and their composition, manufacturing, and identification are regulated.

The tank colors for nitrous oxide, carbon dioxide, nitrogen and oxygen are

nitrous oxide = blue

carbon dioxide = gray

nitrogen = black

oxygen = green

What is the granular materials in the absorbent canister made of? What compound is formed as CO2 is absorbed?

calcium hydroxide and water, with small amounts of potassium, sodium or barium hydroxide to speed up the uptake of CO2

CO2 is removed by an exothermic reaction with the formation of calcium carbonate

How to calculate Minute volume = total amount of gas delivered to patient in 1 minute

tidal volume X RR

Definition of Positive end expiratory pressure (PEEP)

maintains a controlled minimum pressure in the airways at the end of expiration, preventing collapse of the small airways during mechanical ventilation

highest pressure that can be generated during breathing cycle and can be preset by user on some ventilators

Maximum inspiratory pressure

Piston ventilator utilizes an electrically driven piston to deliver a preset volume to the breathing circuit. Maximum working pressure cannot be set, what is the potential risk of it?

BAROTRAUMA POTENTIAL

Straight laryngoscopes (Miller, Wisconsin) are for animals with _____ jaw

Absence of flange good for jaws that don't open wide - improves visibility

Which animal species is Macintosh LARYNGOSCOPES good for?

NHP

VGELS covers?

Supraglottic airway devices

Rabbits (size 1), cats (size 2), dogs/pigs (size 4)

Mask seal (for LMAs) inflated to 20 cm water

Difference between Vgels and LMA

LMAs have an inflatable cuff, vgels are designed to match anatomy of specific animal

Palpebral response is unreliable in accessing anesthesia depth in which animal species?

Rabbits may maintain even at deeper planes

Lost early with barbiturates, well maintained with ketamine

Which regulations oversee waste anesthetic gas?

1. National Institute for Occupational Safety & Health (NIOSH)

Oversee research, education & rule making as they relate to occupational illnesses

2. Occupational Safety & Health Administration (OSHA)

Provide investigative, enforcement & standard enacting responsibilities

What exposure concentration of nitrous oxide (N2O), halothane, and enflurane should be follow for a 8 hour workday

nitrous oxide (N2O), halothane, and enflurane of 50, 50, & 75 ppm for a normal 8 hour workday.

What can be used to sample air? (monitor waste anesthetic gas)

Infrared spectrophotometry*

If scavenge system is not available, rodent surgery can be performed when using _____?

Use hard ducted Class II, B2 BSC

Preferred injectable anesthetics agents in rodent?

Ketamine combinations, usually with xylazine or xylazine plus acepromazine: preferred anesthetic when the equipment for inhalant anesthesia is not available

Ketamine/xylazine combos: ocular lesions (KCS, irreversible corneal lesions, reversible cataracts)

Telazol or Barbituates (Pentobarbital, thiopental, inactin) have narrow safety window, not recommended

Atropine doesn't work in rat because?

rat has hepatic atropine esterase

What anatomy structure in guinea pigs makes them hard to be intubated?

Palatal Ostium - hystricomorphs

Can pedal reflex be used to assess anesthesia plane in guinea pigs?

Pedal reflex not reliable

IM anesthetic injections should be avoided in guinea pigs because?

self mutilation

What anesthetic injectables are recommended in guinea pigs?

Ket/xy is recommended (large margin of safety)

Telazol is not effective

What makes inhalant less desirable in guinea pigs?

Significant breath holding*

Do not use induction boxes, Breath-holding can result in a sudden deep breath of anesthetic gas followed by respiratory and/or cardiac arrest

Injectable recommended prior to inhalation anesthesia

What analgesic is recommended in guinea pigs?

Meloxicam provides good analgesia

Warnings:

Aspirin 🡪 ototoxic

Naproxen induced ulcerations (at high doses)

Naproxen induced GI ulceration can be prevented by misoprostil, but not famotidine

What anesthetic injectables are recommended in hamster? route to give?

Ket/Xyl and Telazol are considered safe and effective in Syrian hamster

All should be given IP d/t muscle necrosis when given IM

Use caution to avoid injecting testicles when doing IP injections!

What anesthetic injectables are recommended in gerbil?

Telazol and ketamine/medetomidine safe in Mongolian gerbils

Pentobarbital = profound hypothermia

Inhalant (iso or sevo) - safest and most reliable; may need lower concentrations of anesthetic gas compared to mice/rats

What is the volume for IM injections in rabbits?

Injections should be limited to 1.5 ml in NZW & 1.0 ml in Dwarf rabbits

Rabbits ears are very sensitive. What should be used for venipuncture?

Use EMLA (lidocaine-prilocaine) cream on the ear for venipuncture

EMLA cream needs ONE HOUR to be effective

Atropine is not effective because?

50% of rabbits have atropinesterase

but glycopyrrolate works

What side effect can benzocaine cause in rabbits?

methemoglobinemia

Detomidine should be avoided in rabbits because it can cause?

Causes myocardial necrosis and anorexia

use other alpha-2 agonists

Cholestyramine given post-operatively may reduce _____________

anti-microbial induced mortality

Cholestyramine- a bile acid sequestrant. It works by binding to bile acid in intestines. Once it attaches to the bile acid, it forms a complex and is removed from your body.

Avoid these antibiotics __________ because they can cause clostridial enterotoxemia

Amoxicillin, ampicillin, cephalothin, clindamycin, and lincomycin

What INJECTABLE ANESTHESIA are recommended in rabbits?

Ketamine/Xylazine

Low dose Ket/Dexmedetomidine

*Antisedan reversal with twice the volume*

Telazol - nephrotoxic - best to avoid

Propofol

Best choice for CRI, does cause apnea

What is the most reliable measure anesthesia depth in rabbits?

Pinna reflex

What is the recommended Preoperative Fasting period for Callitrichids (marmosets, tamarins) versus other NHPs?

Generally fasted at least 12 hours

Exception is Callitrichids (marmosets, tamarins) - fasted for only 4-6 hrs. to prevent hypoglycemia

What can be used prior to emergency surgery if fasting was not done?

histamine (H2) receptor antagonists (cimetidine, ranitidine) useful with emergency surgery or pregnant animals in which gastric emptying is delayed

KETAMINE can be used as a sole agent for chemical restraint in which species?

both OWP and NWP

Rapid return to consciousness!

Wide margin of safety

Bloodwork changes

Decreased leukocytes, lymphocytes, TP; Hg, Hct, BG

Bradycardia is especially important in NHPs because?

Neonatal cardiac output is heart rate dependent and bradycardia can be life threatening

Anticholinergics (atropine and glycopyrrolate) are not recommended for cardiac surgery because it can cause?

ventricular tachycardia and bigeminal patterns

What effect does Ketamine/Xylazine have on NHPs?

provides sedation, muscle relaxation and greater analgesia; does cause decreased MAP and HR

What effect does Ketamine/Medetomidine have on NHPs?

sedation, muscle relaxation and analgesia; in NWPs, no negative impact on appetite or return to feeding

What effect does Ketamine/Diazepam have on NHPs?

Provides muscle relaxation and anticonvulsant activity and maintains adequate immobilization; IM injection is painful with unreliable absorption

What effect does Ketamine/Midazolam have on NHPs?

better absorbed after IM injection; provides more anxiolytic sedation; shorter ½ life than diazepam

What effect does Telazol have on NHPs?

light to moderate anesthesia; greater potency allows smaller volume injections (good if using a dart gun); minimal cardiorespiratory effects; decreased body temps; does not significantly alter blood parameters

What effect does Alphaxolone have on NHPs?

Steroid anesthetic; Sole agent for anesthesia; reliable; smooth and rapid recovery

Species specific:

S. sciureus - resp depression and hypothermia

Erythrocebus – HR and RR decreased

What effect does Propofol have on NHPs?

Rapid clearance; can cause apnea (if rapid); good for short procedures; can be used for induction, with boluses or CRI

Species specific:

Rhesus - decreased HR, BP

Cynos - increased in HR

What is a Swan-Ganz catheter used for?

cardiac function, preload volume status, responses to therapeutic interventions; important for major CV surgeries

Is blood type matching essential prior to blood transfusion in Papio spp?

Initial blood transfusion in macaques in Papio spp. do not normally cause acute transfusion rxn because preformed isoantibodies to erythrocyte antigens are absent

Phenylephrine can be used to treat? bradycardia?

- drug of choice to treat isoflurane-induced hypotension; if bradycardia occurs too, add ephedrine

Post-operative myometrial contractions can occur in pregnant NHPs, what can be used to reduce post-op myometrial contractions?

CRI of buprenorphine, single injection of epidural morphine, and CRI of morphine reduces post-op myometrial contractions

What is Tuohy needle used for?

Epidural administration

Needle placed at lower lumbar interspace using the loss of resistance technique

What effect does Acepromazine have on swine?

sedation; may be contraindicated for CV studies

What effect does Diazepam, midazolam have on swine?

good hypnosis and sedation; hypothermia

What effect does Alpha-2s (xylazine, medetomidine) have on swine?

not effective sedatives used alone; xylazine produces hypotension and 1-3o heart block (not satisfactory alone)

What effect does Anticholinergics have on swine?

routine use not necessary unless HR <60bpm; sinus tach can result from indiscriminate use

What effect does Ketamine have on swine?

most commonly used; immobilization with minimal CV depression, poor muscle relaxation

What effect does Telazol have on swine?

short immobilization, produces hypothermia and cardiodepression; can combine with other drugs; not recommended for cardiopulmonary or renal compromised animals

How often should extended-release buprenorphine produce used in pigs?

pigs do NOT need it every 3 days 🡪 prefers every 4-5 days

What EKG abnormality is considered normal in pigs?

Prolonged Q-T interval is normal (may appear abnormal if not used to it)

What can be used to assess anesthesia depth in swine? what is not reliable?

Jaw tone, absence of pedal reflex in response to painful stimuli and a stable HR

Ocular reflexes are not reliable in swine

When pigs are exposed to halothane, what is a common cause of death? predisposed breeds?

MALIGNANT HYPERTHERMIA (PORCINE STRESS SYNDROME)

A genetic condition occurring in Landrace, Yorkshire and Pietrain breeds, but not in mini swine.

autosomal recessive gene (Hal genotype).

ryanodine receptor gene (ryr-1 locus) is the probable site.

uncontrolled increases in intracellular calcium.

What is the first sign of malignant hyperthermia in swine?

1st cardinal sign- increase in end tidal CO2

concurrent tachycardia and tachypnea plus and sometimes an increase in temp.

What can be used to treat malignant hyperthermia in swine?

Dantrolene is the drug of choice (decreases release of calcium from the SR and reverses episode)

Albino and white headed ferrets should be avoided for _______and ______ studies because?

have deficit in vision/hearing

What kind of arrhythmias are common in ferrets?

Arrhythmias common; second & third degree heart block

Isoflurane and ket/xyl can cause enlargement of which organ in ferrets?

Splenomegaly; Sequestration of RBC and alteration of blood parameters

What should be taken in caution when doing blood transfusion in ferrets?

No blood groups = allows for multiple transfusions without cross matching

What sedation agents are commonly used in ferrets?

Acepromazine and a2-agonist

Can ferrets be placed inside a chamber for induction?

violent struggling and digging behaviors - avoid

Diazepam and Midazolam are not recommended as sole agent in ferrets why?

- large volume IM, can cause transient lameness; not recommended as sole agents due to dysphoria, restlessness

Telazol is not recommended as sole agent in ferrets why?

Excellent immobilization; not recommended as sole agent due to rough recovery

Rapid induction and small volume

Use combinations: ket/xy, dexmedetomidine/butorphanol

What effect does Xylazine have on ferrets?

cause hypotension, heart block and ventricular arrhythmias

Morphine dose lower than 0.5mg/kg induce ______ in ferrets

vomiting

NSAIDs used with caution in ferrets because?

ferrets are deficient in glucuronidation pathway and may metabolize slowly

so are cats

Hypothermia can be used as a mean of anesthesia for ferret under _____?

up to 5 days age