3 Preanesthetics Use Alone or in Combination2

8/14/2019 3 Preanesthetics Use Alone or in Combination2

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Pre-anesthetics: Use alone or in

Combination


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No safe anesthetics, only safe

anesthetists

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Options for Preanesthetic Medication or forTemporary Restraint and Sedation:

There are many useful optionsfor an infinite variety of clinicalsituations.

What are some of yourfavorites?

Balanced, multi-modal, andindividualized


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Lytic to parasympathetic nervous system Depress salivary and bronchial secretions

Induces pupillary dilation Increases heart rate - Dose dependent partial blockade of vagaltone Decreases gastric motility and secretions, e.g., ketamine

Prevents severe bradycardia from vagal stimulation, opioids

Avoid in patients with sinus tachycardia or PVCs


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Glycopyrrolate

Dosage-0.005-0.02 mg/kg IM,IV,SQ Decreases gastrointestinal mobility Increase in gastric pH Half-life = 4 hours Less likely to cause excess heart rates than atropine


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Acepromazine

Phenothiazine neuroleptic tranquilizer Neveruse label dose (1.1 mg/kg) UNSAFE! It is much safer to dilute bottle concentration of 10

mg/ml to 2 mg/ml

Never store near directsunlight


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Acepromazine

Dosage 0.01 0.1 mg/kg * Inc sensitivity in breeds with mutation in K9 MDR1

gene?

Total dose less than 2 mg * Use in patients with seizure history is NOT

recommended

*based on route of administration and

individual patient needs


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Expected benefits from the utilization of

minor tranquilizers

(i.e. Diazepam and Midazolam) Enhances the effects by binding to

benzodiazepine site on GABA receptors

Skeletal Muscle Relaxant Anticonvulsant Anxiolytic Sedative Hypnotic


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Diazepam

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Midazolam

(Versed, Hypnovel)

Water sol benzodiazepine Use alone - less than 0.5 mg/kg May be substituted for acepromazine or an

alpha-2 plus opioid as premedication

Useful for dysphoric patients post operative Not an analgesic but 0.1 mg/kg reduces

anesthetic requirements


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Currently Available Sedative/Hypnotics:

Xylaxine (Rompun) Yohimbine

Detomidine (Dormosedan) Medetomidine (Domitor)

Atipamezole(Antisedan)

Dexmedetomidine (Dexdomitor)


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Xylazine Medetomidine - Dexmedetomidine(!-2 : !-1affinity)

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Alpha2Agonists:use for sedation & analgesia


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Alpha2adrenergic receptor

agonists (*listed in order of clinical release)

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Indications for Clinical Procedures

# Non-invasive, mildly to moderately painful,procedures and examinations which require

restraint, sedation and analgesia in dogs and

cats

# Deep sedation and analgesia in dogs inconcomitant use with butorphanol for medical

and minor surgical procedures

# Premedication in dogs and catsbeforeinduction and maintenance of general

anaesthesia.

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Sample uses of multi-modal

Pre-anesthesia

# Dog: Typical demeanor" Dexmedetomidine; 1 5 "/kg IM" Morphine; 0.5 mg/kg IM" Atropine: #only at same time

# Dog: Fractious / Fearful" Dexmedetomidine 1.5 2 "/kg IM with opioid

# Cat:Typical demeanor" Dexmedetomidine; 5 10 "/kg IM" Morphine; 0.05 mg/kg IM

# Cat: Aggressive / Fearful Bad cats:" Ketamine; 2 5 mg/kg IM

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Antisedan (atipamezole hydrochloride)

Indicated for the reversal of the sedative and othereffects of Dexdomitor and Domitor

Potent alpha2antagonist that selectively andcompetitively inhibits the alpha2adrenoceptor

Longer elimination half-life than for dexmedetomidine Administered IM

in dogs, same dose volume as Dexdomitor 0,5 mg/ml but 1/5 volumeas Dexdomitor 0,1

in cats, half the dose volume as Dexdomitor 0,5 mg/ml but 1/10volume as Dexdomitor 0,1

Reversal of Dexdomitor within 5 to 15 minutes Side effects are rare:

vomiting, hypersalivation, diarrhea, muscle tremors, and excitation

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Opiate or Opioid

Opiate: Any drug derivedfrom opium, e.g. morphine

Opioid: Any syntheticnarcotic with opiate-like

activity, but is not derivedfrom opium, e.g. fentanyl


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Morphine

" First opioid used in animal painmanagement

" Opioid, is the Gold Standard, towhich all other opioids are compared

" Dosage:dog: 0.2 0.5 mg/kg

cat: 0.02 0.1 mg/kg

"Potent analgesic properties: dosagedepends on route of administration,pain level and responses


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Morphine Demerol Oxymorphone Hydromorphone Fentanyl Sufentanil Remifentanil Butorphanol Buprenorphine Tramadol Naloxone (antagonist)


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Mu Opioid Agonists Continued

# Hydromorphone:* Dosage:"Dogs: 0.1-0.2 mg/kg IM,IV,SQ"Cats: 0.05- 0.1 mg/kg IM,IV,SQ

# Oxymorphone:* Dosage:"Dogs: 0.05-0.1 mg/kg IM,IV,SQ"Cats: 0.025-0.05 mg/kg IM,IV,SQ

*Provides moderate to profound analgesia lasting 2-4hours (Hydromorphone) and 3-4 hours (Oxymorphone)


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Transdermal Opioid Pre-anesthesia

The fentanyl patch$effective but not officially approved for veterinaryusage in many countries. Available in four sizes releasing fentanyl at

25, 50, 75, and 100 micrograms/hour. Apply 8 to 12 hours prior to

anesthesia.

Dosages# Cats: 25-50 mcg/hour patch# Dogs: 3-10 kg25/hour patch

" 10-20 kg-50/hour patch" 20-30 kg-75/hour patch" 30 kg100/hour patch


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Transdermal Fentanyl Guidelines

Must be in contact with skin foreffective usage in dogs or cats

Absorption is slow: allow 8-12 hours fordesired analgesia

Duration is up to 72 hours Caution: Keep away from children and

avoid accidental human exposure


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Opioids by Constant Rate Infusion

Fentanyl in dogs and cats (IV administration)

" Dogs: loading dose (0.002 mg/kg) followed by 0.001-0.006 mg/kg/hour

" Cats: loading dose (0.001-0.002 mg/kg) followed by 0.001-0.004 mg/kg/hour

Sufentanil in both dogs and cats (IV administration)

" Loading dose(0.002-0.005 mg/kg) followed by 0.0001-0.0002 mg/kg/hour

* Adjust dosages for each patient needs and responses


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Tramadol Activity

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Tramadol Dosage and Duration

Dogs

# 0.1-0.2 mg/kg IM or IV# 1-10 mg/kg orally based on

level of pain

# Duration, 2-4 hours

Cats

# 0.05-0.1 mg/kg IM or IV# 1-2 mg/kg orally based on

level of pain

# Duration , 2-4 hours


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Opioid Agonist Side Effects

Excessive CNS depression Respiratory depression Cardio vascular depression CNS excitement / delirium Vocalization

Treat as symptoms indicate

Excessive dose

May need oxygen

Reduced rate and output

Agent specific ?

Individual response, may needadjunct tranquillizer

May reverse with antagonist if

adverse effects persist


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Opioid Agonists/antagonists

! Usage alone or in combination with tranquilizers orsedatives is increasing in clinical practice

Buprenorphine Butorphanol


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Currently Available Agonist-Antagonists

* Marketed in Europe as Butomidor ** Marketed in Europe as Bupaq

Pentazocine Naloxone (antagonist)Nalbuphine

Buprenorphine **Butorphanol*


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Buprenorphine HCl

Approved in Europe as Bupaq vet 0.3mg/mlsolution for injection

Indications:# Dogs: Post-operative analgesia

"Potentiation of the sedation effects of centrallyacting agents

# Cats: Post operative analgesia


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Buprenorphine Duration

As sole medication:"Mild sedation -15 minutes post injection"Analgesia - 30 minutes post injection"Peak effect 1-1.5 hours"Expected duration- up to 6-8 hours

In combination with other analgesics, sedatives oranesthetics.. adjust dosages due to synergistic

effects on duration and patient responses


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Butorphanol Tartrate ,10mg/ml*

Marketed in Europe as Butomidor

# Indications: Horse"As a short term analgesic"As a sedative and pre-anesthetic

(combine with an alpha2agonist)

# Indications: Dogs and Cats"As an analgesic"As a sedative"As a pre-anesthetic and part of the

anesthetic protocol


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Butorphanol Dosages:

Route of Administration in Cats

# As an analgesic:" 15 minutes prior to anesthetic recovery:" 0.4mg/kg SQ or 0.1 mg/kg IV

# As a sedative/analgesic:" Butorphanol, 0.4 mg/kg SQ plus" Medetomidine , 0.05 mg/kg SQ

# As a pre-anesthetic:" Butorphanol, 0.1 mg/kg IV plus" Medetomidine, 0.04 mg/kg IV which may be followed with

ketamine, average dose of 1.5 mg/kg IV. Dose to desired effect!


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Opioid /Alpha2AgonistsAdvantages

Reversible

Many combinations in useProvide profound sedation and analgesia

Significantly reduce anesthetic dose requirements


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Opioid Agonists/Alpha2AgonistsSide Effects

Bradycardia

Reduced perfusion

Respiratory depressionReduced oxygen saturation


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Opioid Agonist-antagonist/Alpha2 agonists

# Provides desirable sedation and analgesia# Opioid duration prolonged by alpha2agonist# Alpha2cardiovascular side effects reduced by the opioid# Reduced dosages of each drug


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Pre-anesthesia in the Difficult / Mean

Patient


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WARNING

Avoid in patients with respiratorycompromise, HCM!!!, seizure history,

increased IOP and ICP

Anger Management in AggressivePatients

Ketamine or Telazol Combinations With Alpha2Agonists AndOr Opioids

Advantages# May be administered SQ or IM# Safety factors to patients as well as

personnel# Physiologic stability# Recovery within 2 hours, but

occasionally delayed

B l d A l i


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Balanced Analgesia

Multi-Modal Analgesia Similar to "balanced anesthesia Combination of complimentary methods or drug classes Maximize effectiveness and minimize side effects of each

drug = balanced


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Acepromazine & OpioidAce at 0.025 mg/lb (0.05 mg/kg), max 1.0 mg, IM, or IV

Hydromorphone at 0.05 mg/lb (0.1 mg/kg) IM, or IV

# Substantial and reliable# Not recommended for older or

compromised patients

# Prolonged effect (+++)# Return to Cognitive recovery

often requires 4-6 hrs. +# Optional anticholinergics# Alternative opioids$


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Controversies with Perioperative Drugs

# Tranquilizer Acepromazine" Evidence of increased risk with

seizure history no

" Breeds questionable?# Anticholinergic Atropine

" Pre-emptive - indications?" Indiscriminant use no" With alpha2agonists - questionable?

Controversies in Use of Pre-anesthetics;


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Controversies in Use of Pre anesthetics;

When to use atropine

Originally used to prevent bradycardia and excessive salivation during morphine/diethyl ether anesthesia

Currently used to prevent bradycardia

Is it needed with currently used pre-anesthetics? Is it needed with new inhalant anesthetics?

Conclusion !$Should be based on individual patient needs


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Use of Atropine with Alpha 2Agonists

# Helps maintain higher heart rates# Prolongs hypertension# Increases myocardial oxygen demands# Increase in cardiac arrhythmias following IV administration

during alpha2sedation

# Not routinely recommended


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Additional Controversies

# Analgesics are not needed during general anesthesia# Most anesthetics have inadequate analgesic properties

when used alone but$Anesthetic/analgesic combinationsprovide desirable perioperative pain management


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Controversies Continuing

# Alpha2Agonists are anesthetics at high

doses?

" High doses prolong sedation analgesia,side effects and recovery times

# Ketamine has excellent anesthetic andanalgesic properties when used alone? (this

is not proven)

# Ketamine provides somatic analgesia butinadequate visceral analgesia?

" Ketamine in combination with pre-anesthetics are very useful clinical

protocols


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Patient Preparation

# Equipment check list* Oxygen Supply

* CO2absorbent

* ET tube and mask

* Breathing system

* Inhalant anesthetic

* Scavenging system

* Electronic monitoring

# IV catheter and fluids

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Maintaining Anesthesia

# Many options including:"Multiple IV injections or constant

rate infusions of injectableanesthetics

"Inhalant anesthetics ( isoflurane orsevoflurane)

"Concurrent usage of local orregional nerve blocks

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Documents

3 Preanesthetics Use Alone or in Combination2