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74 Cards in this Set
- Front
- Back
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Systems affected by Anaesthesia
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Cardiovascular
Respiratory Hepatic Renal |
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Definition of Hypoxia
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SpO2 <60mmHg
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Stages of Anaesthesia
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1. Voluntary Excitement
2. Involuntary Excitement 3. Surgical Anaesthesia 4. Bulbar Paralysis |
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Planes of Stage 3 Anaesthesia AND which one do we use for most surgical procedures?
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1. Light
2. Medium (most sx procedures) 3. Deep 4. Very deep |
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Eye positions during 4 planes of Sx anaesthesia
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Light - central constricted
Medium - ventromedial Deep - central constricted or dilated Very deep - central dilated |
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Why do we fast patients before anaesthesia?
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Decreased lower oesophageal sphincter tone and positioning of patient for sx may predisp to regurg. Oesophagitis, oesophageal stricture. Regurg may lead to aspiration due to impaired laryngeal function.
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How long prior to anaesthesia for dogs and cats do we remove food and water?
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Food 12 hours
Water - up until premed |
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Reasons for premedication
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Calms patient, easier handling
Decrease stress, smoother induction Better recovery Some: decrease resp secretions, prevent bradycardia, relax muscles Can decrease dose of more depressant agents Pre-emptive analgesia |
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"Families" of Premed agents
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Sedatives
Analgesics Dissociatives Anticholinergics Antihistamines |
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3 types of sedatives for Premed
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Phenothiazines
Benzodiazepines Alpha-2 agonists |
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Two types of analgesics for premed
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Opioids
NSAIDS |
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Drug name of phenothiazine for premed + 4 advantages of it
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Acepromazine
Sedative (dose dependent) Anti-emetic Antihistamine Anti-arrhythmic |
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Onset and duration of action of ACE
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Both long (5min onset w IV tho)
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CV effects of ACE
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Depresses CV system - alpha-1 antagonist BUT good anti-arrhythmic.
Peripheral vasodilation - decreased TPR - causes reflex tachycardia to maintain MAP |
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Resp effects of ACE
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Minor depression but also lower metabolic requirement
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5 Disadv of ACE
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Lowers seizure threshold
Slow metabolism No reversal No analgesia Vasodilation - hypothermia |
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7 Contraindications for ACE
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Young, Old, Sick (YOS)
Severe heart dz Liver dz Epilepsy Myelography |
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3 types of Benzodiazepines
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Diazepam
Midazolam Zolazepam |
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Difference btn Diazepam and (Midazolam & Zolazepam) and implication of this
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M and Z are both water soluble, so better absorption after IM or SQ administration
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Sedative effects of BZs
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Unpredictable in most spp.
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What type of receptors do BZs act on?
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GABA potentiators - anxiolytics
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Why do we use BZs?
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Anticonvulsants
Muscle relaxants |
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CV effects of BZs
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Minimal
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Resp effects of BZs
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Minimal
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BZ metabolism?
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By liver! Avoid in liver dz, prolonged action.
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Speed of IV administration of Diazepam?
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SLOW
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Is Diazepam reversible?
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Yes - flumazenil
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What do we use instead of ACE for young, old, CV disease, epilepsy or myelography?
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Diazepam
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Alpha-2 agonist most commonly used in smallies incl. trade name
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Medetomidine - Domitor
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Two main uses of Medetomidine
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Sedation for minor procedures
Restraint of Aggressive animals |
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Is Medetomidin reversible?
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Yes - Atimpamezole (Antisedan)
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How does Medetomidine work i.e. what is its mechanism of action?
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Stimulates presynapse so inhibits release of noradrenaline centrally
-sedation -analgesia -cardiopulmonary depression Stimulates postsynapse peripherally -peripheral vasoconstriction |
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Side effects of Domitor
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Emesis (cats)
Marked CV depression Arrhythmogenic Biphasic BP change Decreased resp rate and tidal volume |
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CV effects of Domitor
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Profound depression.
Biphasic BP change. Arrhythmogenic. Decreased HR |
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Resp effects of Domitor
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Decreased RR and TV
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4 Advantages of Medetomidine
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Profound sedation (dose dependent)
Excellent anticonvulsant Good muscle relaxation Good analgesia |
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Metabolism of Medetomidine
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Liver. Or reverse w antisedan (atipamezole)
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5 types of Opioids used for premeds
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Morphine
Methadone Meperidine Buprenorphine Butorphanol |
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3 classes of opioids (receptor-wise)
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Pure opioid agonists
Partial opioid agonists Opioid agonist-antagonists |
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Morphine contraindications
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If vomiting is contraindicated
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Morphine receptor function
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Pure opioid agonist at mu and kappa
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Onset and duration of morphine
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Onset 10-30 min
Duration 4-6 hours |
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CV effects of morphine
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Mild.
Vagal stimulation leads to bradycardia. |
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Resp effects of morphine
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Depressive
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What speed do we give morphine IV and why?
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Slowly because otherwise it can cause histamine release
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Is morphine reversible?
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Yes
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How does morphine wear off?
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Glucuronidation - mostly liver metabolism
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Side effects of morphine
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Vomiting
CRTZ Constipation Bradycardia Resp depression |
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Advantages of morphine
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Dose-dependent analgesia
Dose-dependent sedation in dogs Cheap! Moderate duration of action |
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Methadone side effects
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CRTZ
Constipation Bradycardia Resp depression i.e. same as morphine but no vomiting |
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Compare Meperidine to Morphine
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10% the potency of Morphine
No vomiting Faster onset, shorter duration No bradycardia Don't give IV in dogs |
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Drug name of Temgesic
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Buprenorphine
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Trade name of Buprenorphine
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Temgesic
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Buprenorphine receptor activity
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Partial Opioid Agonist
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Compare buprenorphine to morphine
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More potent than morphine
No vomiting Slower onset Shorter duration |
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Trade name of Butorphanol
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Butorphic
Torbugesic |
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Drug name in Butorphic
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Butorphanol
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Drug name in Torbugesic
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Butorphanol
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Compare Butorphanol to morphine
-potency -onset -duration |
More potent than morphine
Slower onset Shorter duration |
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What do we always use Ketamine with?
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A muscle relaxant (benzodiazepine or alpha-2 agonist
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Ketamine CV effects
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Stimulatory
Take care with pre-exisitn tachycardia or e.g. hyperthyroid cats |
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Ketamine resp effects
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Minimal
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How does Ketamine wear off?
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Liver metabolism
There is no reversal |
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What does Ketamine premed do to dogs?
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Causes excitement
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What does Ketamine premed do to cats?
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Dose-dependent sedation
Great for aggressive cats |
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What stage of anaesthesia is Ketamine most commonly used for?
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Induction (with Diazepam)
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Name two anticholinergics used in premeds?
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Atropine, Glycopyrrolate
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What class of drug is Atropine?
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Anticholinergic
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What class of drug is Glycopyrrolate?
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Anticholinergic
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What do we use Atropine for in premeds?
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Offset potential bradycardia caused by other agents or procedures
Decrease salivary and bronchial secretions in cats Decrease laryngospasm in cats |
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What are the actions of Atropine (and glycopyrrolate) on the nervous system?
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Sympathomimetic, Parasympatholytic
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Give 4 disadvantages of Atropine
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No sedation
No analgesia Arrhythmogenic Decrease GIT motility |
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Effects of Atropine on CV system
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Increases HR
Arrhythmogenic |
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Resp effects of Atropine
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Bronchodilation
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