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Pharm Test 2 > SA pre-med and sedation > Flashcards

SA pre-med and sedation Flashcards

1
Q

Why pre-medicate?

A
  1. In preparation for general anesthesia
    >To provide sedation and pre-emptive analgesia
  2. Sedation but animal remains conscious in a situation for diagnostics or minor surgery
    >They can swallow and maintain airway and breathing on their own
    >Analgesia
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2
Q

when is monitoring important during sedation?

A
  • When drugs taking effect
  • During maximal sedation
  • Recovery phase
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3
Q

Advantages of pre-medication

A
  1. Facilitate safe handling
  2. Provide analgesia
    * Pre-emptive or before surgery
  3. Balanced general anesthetic approach
    * Lowers the dose of anesthetic induction drugs
    * Smooth induction & endotracheal intubation
    * Lowers the dose of inhalational anesthetics

§ 2 and 3 will minimize –ve CV and Resp effects

  1. Contributes to a smooth recovery
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4
Q

Disadvantages of Premedication

A

§ Cost
* Relative disadvantage because you save on
induction and inhalational anesthetic doses

§ Time delays
* Have to wait for onset of effects

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5
Q

Patient Considerations for Drug Selection

A
  1. Presenting complaint of animal
    * Duration of procedure/Sx
    * Sedation level required
  2. Signalment
    * Age; Breed; Personality
  3. Health status
    * CV, resp, liver, renal, endocrine, CNS
    § ASA status framework for drug choice
    * ASA I-V
    § Patients with higher ASA —-> higher risk
    * ASA I -normal to an ASA V-not expected to survive
  4. Level of pain
  5. Last time animal has eaten
    * Vomiting a concern?
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6
Q

drug classes used as pre-anesthetic sedatives in SA

A

1) anticholinergics
2) phenothiazines
3) alpha2 agonists
4) benzodiazepines
5) opioids
6) others, eg, ketamine, propofol, alfaxalone

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7
Q

common anticholiergics used as pre-anesthetic sedatives

A

Atropine, glycopyrrolate (IM, SC, IV)

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8
Q

common phenothiazines used as pre-anesthetic sedatives

A

Acepromazine (IM, SC, IV)

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9
Q

common alpha2-agonist used as pre-anesthetic sedatives

A

Dexmedetomidine, Medetomidine (IM or IV)

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10
Q

common benzodiaepines used as pre-anesthetic sedatives

A

Diazepam (IV only) - Midazolam (IM, SC, or IV)

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11
Q

common opioids used as pre-anesthetic sedatives

A
  • Mu-agonists – morphine, hydromorphone, fentanyl, oxymorphone (IV, IM or SC) or meperidine (not IV)
  • Kappa-agonists – butorphanol (IM, SC, IV)
  • Partial Mu-agonists – buprenorphine (IM, SC, IV)
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12
Q

what is neuroleptanalgesia? how do we achieve it and what are the advantages?

A

§ Sedation/tranquilization + Analgesia

  • Drugs from different classes given together
  • Offers better sedation
  • Provide added benefit of the other class
  • Lowered doses of each
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13
Q

some possible combinations to achieve neuroleptanalgeisa

A
  • Acepromazine + Opioid
  • Alpha2-agonist + Opioid
  • Benzodiazepine + Opioid
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14
Q

drugs that can be used for sedation when there is no IV access

A

§ Alfaxalone or Ketamine

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15
Q

signs of sedation: none, mild, moderate, profound

A

None:
Bright and alert - no sedation and/or patient is even more excitable - dysphoric (excited, anxious, difficult to restraint in lateral recumbency, very interactive and responsive, vocalizing, very reactive to noise or touch

Mild:
Calm - minimal sedation, quiet but still alert and aware of surroundings, can hold head up, mild resistance to restraint in lateral recumbency, moderate response to noise or touch

Moderate:
Moderate sedation - quiet, relaxed, minimal restraint required to position in lateral recumbency, mild response to noise or touch, but head is mainly down and relaxed

Profound:
Profound sedation - quiet, very relaxed, no restraint necessary in lateral recumbency, no response to noise or touch and head remains down.

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16
Q

characteristics of the ideal premedication or sedative agent

A
  1. Provide reliable and consistent sedation & anxiolysis
  2. Minimal to no negative effects
  3. Provide analgesia
  4. Be Reversible
  5. Reduce the dose of other sedatives or anesthetics
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17
Q

two common anticholinergics

A

glycopyrrolate and atropine

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18
Q

effect of anticholinergics on Parasympathetic tone, and why they are given? effect on salivary secretions?

A

-Administered to reduce parasympathetic tone
-Vagal tone may be increased with opioids, endotracheal intubation, IV anesthetics or surgery
> Anticholinergics are given to maintain HR during anesthesia and surgery
-reduce salivary secretions

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19
Q

anticholinergics cardioresp effects on HR, CO, contractility, BP, RR?

A

HR: up up
CO: up
contractility: NC
BP: NC or up
RR: NC

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20
Q

anticholinergics are given with:
not given with:

A

Given with
* Opioid and acepromazine drug combinations
* Anticholinergics ARE NOT indicated with α2-agonists

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21
Q

most popular phenothiazine

A

acepromazine

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22
Q

acepromazine acts on what receptors, and how? What are the effects?

A

Dopamine (D2) receptor antagonist
-Gives sedation, anxiolysis, anti-emetic, reduces MAC, Anti-arrhythmic
-Calming effect even at lowered doses

Alpha1-antagonist
– vasodilation & may produce hypotension
>Especially in sick or dehydrated patient

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23
Q

higher doses of acepromazine correspond to? when would we give a high dose?

A

longer duration of action, but not necessarily higher sedation level
-not typically given, as generally combined with an opioid

24
Q

when do we give low doses of acepromazine

A

-Given for mild effects before or after surgery -In stable patients

25
Q

acepromazine cardioresp effects on HR, CO, contractility, BP, RR?

A

HR: down (or up)
CO: down (or up)
contractility: +/-
BP: down down down
RR: NC or down

26
Q

how does acepromazine effect body temp?

A

decrease

27
Q

when should we not administer acepromazine? ie what clinical signs.

A

shock or dehydration

28
Q

α2-agonists Mechanism of Action, and effects

A
  • Bind to α2-adrenergic receptors in the central nervous system
  • decrease NE and epinephrine levels
  • Sedation, analgesia, and muscle relaxation
29
Q

xylazone, romifidine, and dexmedetomidine act on what receptor, and how?

A

α2-agonists

30
Q

α2-agonists – Central Effects

A
  • Produce sedation centrally
    Presynaptic α2 – adrenoreceptor reduces release of epinephrine and norepinephrine
31
Q

how does using higher doses of dexmedetomidine change the effect of the drug?

A
  • Sedation level plateaus – using high doses outside of recommended range increase the duration of sedation and negative effects but does not increase sedation level
32
Q

what can we mix an alpha2 agonist with to ensure a stressed, anxious animal will have consistent sedation?

A

opioid, benzodiazepine

33
Q

effect of alpha2 agonist on inhaled anesthetic

A

-dramatic MAC reduction, inhalant sparing properties

34
Q

α2-agonists – Peripheral BP Effects

A
  • Biphasic blood pressure response - seen more with IV than IM administration

Pre-synaptic α2
* Reduces NE resulting in decrease BP
> Low doses used in people
> This effect predominates in people

Post-synaptic α1 and α2
* Causes contraction
* This effect predominates
> Doses used in veterinary medicine
> Difference in receptor subtype & #
> α2B

35
Q

α2-agonist - Dexmedetomidine cardiovascular effects (BP, HR, CO)

A

Increase in BP
* > dogs than cats
* Wanes over time and in combination with inhalants or other drugs that vasodilate
* As a sedative we DO NOT see clinical hypotension

Reduction in HR and associated bradyarrhythmias
* From the increase in BP
* And central sedation effects

Reduction in Cardiac output is from the reduction in HR
* Using anticholinergic in sedation phase is not indicated
* Treating HR with anticholinergic increases cardiac workload with period of worsened bradyarrhythmias without improving Cardiac output

36
Q

α2-agonists - Dexmedetomidine disadvantages

A

the cardiovascular effects

37
Q

α2-agonists - Dexmedetomidine advantages

A
  1. Analgesia and sedation
  2. Injectable and inhalant sparing properties
  3. Reversible
  4. Not scheduled
38
Q

dexmedetomidine cardioresp effects (HR, CO, contractility, BP, RR)

A

HR: down down down, bradyarrhythmias
CO: down down, due to low HR
Contractility: NC
BP: up up up up when IV, species variation
RR: slight down

39
Q

dexmedetomidine effect on temp, vomiting, urinary volume, endocrine, alalgesia

A

temp: NC or down
vomiting: possible
urinary: volume up
endocrine: hyperglycemia
analgesia: +++

40
Q

Benzodiazepines – Diazepam & Midazolam disadvantages

A
  • Unreliable or poor sedation alone
    > Unless sick or older small animal
  • Scheduled – records required
  • Potential for abuse
  • NOT an analgesic
41
Q

Benzodiazepines – Diazepam & Midazolam advantages

A
  • Minimal negative cardio-respiratory effects
  • Reversible - flumazenil
42
Q

bensodiazepnies cardioresp effects (HR, CO, contractility, BP, RR)

A

Minimal negative cardio-respiratory effects

43
Q

use of opioids for sedation: what animals are they good for? what can they be combined with to increase efficacy? what animal are they not great for?

A

Opioids provide mild sedation
* Even in healthy or young dogs
* Better sedation when administered with sedative
> Acepromazine or α2 - agonist
* Healthy cats – poor sedation alone

  • Sick animals better sedative effects
    > Opioid alone gives very good sedation in ASA 3-4 patients
    > Additional strong sedative such as acepromazine or dexmedetomidine is not required
44
Q

opioids advantages

A
  1. Effective Analgesia with sedation
  2. Minimal CV depression
  3. Reversible
  4. Relatively inexpensive
45
Q

opioids disadvantages

A
  1. Scheduled / require records
  2. Potential for abuse (staff)
  3. Side effects
46
Q

opioid side effects

A
  • Dysphoria, panting
  • Respiratory depression in sick or high doses
    > pure mu-agonists only more common as CRI
  • Nausea, vomiting, defecation
  • Inability to ambulate
  • Ileus (rare SA, problem in equine)
  • Hyperthermia in cats with general anesthesia
47
Q

opioid cardioresp effects (HR, CO, contractility, BP, RR)

A

HR: down, > mu-agonists
CO: NC or down
contractility: NC
BP: NC to mild down
RR: down down, panting

48
Q

opioid effects on temp, vomiting, antitussive, analgesia

A

temp: down, or up in cats
vomiting: ++ mu-agonists - hydromorphone/morphine
anti-tussive: ++
analgesia: ++++

49
Q

when is resp depression most pronounced with opioids?

A

high doses or CRI’s - thoracic disease, very young or old, in combination with inhalant or general anesthetics

50
Q

resp depression from opioids leads to what? why?

A

Hypoventilation
* An increase in PaCO2 – carbon dioxide levels in the blood
* Not a reason to withhold in a sick or painful patient, but need to monitor
* The sicker the patient more monitoring required related to ventilation especially when with GA

51
Q

what drugs are given as sedatives if:
1. Included after when the original sedation doesn’t work
2. Initially in a very aggressive/scared animal
3. In cases where more immobility deemed necessary
* Benefit is short duration immobility
* Cardio-respiratory depression dose related

A

ketamine, propofol, alfaxalone

52
Q

ketamine advantages

A
  • ADV: can use in cats and dogs, small volumes
53
Q

ketamine disadvantages

A

Ketamine behavioural effects in recovery, rough recoveries possible, no reversal, not ideal in CKD or HCM

54
Q

propofol advantages

A
  • ADV: short duration; rapid metabolism even liver dz; cats and dogs
55
Q

propofol disadvantages

A
  • DISADV: Need IV; Cannot start with this protocol if animal aggressive
56
Q

alfaxalone advantages

A
  • ADV: IM route possible – NOT contraindicated in sick patients with renal or cardiac disease

Pharm Test 2 (16 decks)

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