Anesthesia of the Dog & Cat Flashcards
What are the 5 steps of anesthesia?
- pre-anesthetic evaluation & patient preparation
- pre-anesthetic medication
- anesthetic induction
- maintenance & monitoring
- recovery
What does patient assessment entail?
- full physical exam
- medical history
- basic hematology
What should you take into consideration in a full physical exam while assessing a patient for anesthesia?
- age
- temperament (pre-hospital: gabapentin, trazadone…)
- breed (brachycephalic, greyhounds…)
What should you take into consideration in a medical history while assessing a patient for anesthesia?
- past problems, previous adverse drug responses
- anesthetic events
- present problems - medication
What should you take into consideration in basic hematology while assessing a patient for anesthesia?
PCV, TP, BUN, Gluc
What assessment & diagnostic tests should you do when assessing an older/sick patient for anesthesia?
- CBC, serum chemistry, u/a advisable (in older or ill patients or on the basis of the physical exam & history)
- radiograph thorax (trauma, respiratory problems)
- ECG, echocardiography (murmurs, arrhythmias)
With older or sick patients when should you delay anesthesia until?
- further assessment is performed
- patient is stabilized
- anesthetic risk is established
What should you communicate to a client prior to anesthesia?
- anesthetic risk
- set expectations
- patient preparation starts at home
What are prehospital anxiety drugs & how are they given?
- trazadone & gabapentin
- PO, 2 hours prior to drop off
What are the categories in the ASA physical status classification?
- ASA 1: normal healthy patient
- ASA 2: mild systemic disease - no functional limitations
- ASA 3: severe systemic disease - definite functional limitation
- ASA 4: severe systemic disease that is a constant threat to life
- ASA 5: moribund, not expected to survive w/o operation
What are the rules for food & water prior to anesthesia?
- allow free access to water (esp in older animals & those w/ increased fluid requirements)
- recommend fasting before anesthesia (young animals require shorter fasting times - hypoglycemia; 6-16 wks: 4 hrs; older than 16 wks: 6-8 hrs)
What information is important for anesthesia protocol?
- physical exam
- age
- temperament
- surgical procedure
- clinical setting
What 4 types of drugs should be included in an anesthetic protocol?
- premed: sedative + opioid
- induction
- maintenance: inhalant +/- opioid +/- local anesthetic
- post operative pain management: NSAID, opioid
What are the aims of premedication?
- sedation & anxiolysis (fear free)
- facilitate animal handling
- balanced anesthetic technique
- analgesia
- smooth & quiet recovery
What can you use for a premedication?
Opioid (hydromorphone, methadone, butorphanol, buprenorphine) + sedative (acepromazine, dexmedetomidine, midazolam) +/- anticholinergic (atropine, glycopyrrolate)
- do not co-administer an anticholinergic w/ dexmedetomidine
What is the premedication protocol for calm dogs (ASA 1-2)?
- Acepromazine + hydromorphone
OR - dexmedetomidine + hydromorphone
What is the premedication protocol for excited, agitated dogs (ASA 1-2)?
- acepromazine + dexmedetomidine + hydromorphone
What is the premedication protocol for aggressive dogs (ASA 1-2)?
- acepromazine + dexmedetomidine + hydromorphone + ketamine
What is the premedication protocol for cats (ASA 1-2)?
dexmedetomidine + hydromorphone
What do you use for the heavy sedation of cats?
- Kitty magic (Dexmedetomidine + ketamine + butorphanol (opioid))
- dexmedetomidine + midazolam + butorphanol
- alfaxalone + butorphanol + midazolam
What should you remember about heavy sedation (kitty magic) of cats?
- for more reliable sedation used a ketamine-based protocol
- provides general anesthesia for invasive short procedures
- monitor patient!
- provide life support
Karl, 6 m male DSH was given Midazolam, Butorphanol, Isoflurane as needed, & lidocaine intra-testicular block for castration. What is wrong here?
- midazolam can cause excitement in young, healthy animals
- on these meds Karl is excited, hyperactive, & unrestrainable
young cat given midazolam + butorphanol causing excitement & o will be back in 2 hours to pick him up, which drug can we use to sedate him? a) reverse midazolam w/ flumazenil b) dexmedetomidine c) ketamine d) alfaxalone e) acepromazine ?
topped up w/ dexmedetomidine & then place catheter to proceed w/ induction
a) will get rid of side effect but he will not be sedated enough to perform neuter
c) would need high dose of ketamine to override midazolam & this is heavy sedation for such a quick procedure
d) again would need a higher dose
e) not a great sedative in cats & takes 1/2 hr to work
What is on the pre-induction part of the anesthetic safety checklist?
- patient NAME, owner CONSENT & PROCEDURE confirmed
- IV CANNULA placed & patent
- AIRWAY EQUIPMENT available & functioning
- ET CUFFS checked
- ANESTHETIC MACHINE checked today
- adequate OXYGEN for proposed procedure
- BREATHING SYSTEM connected, leak free, & APL VALVE OPEN
- person assigned to MONITOR patient
- RISKS identified & COMMUNICATED
- EMERGENCY INTERVENTIONS available
What is on the pre-procedure - time out part of the anesthetic safety checklist?
- patient NAME & PROCEDURE confirmed
- DEPTH of anesthesia appropriate
- SAFETY CONCERNS COMMUNICATED
What is on the recovery part of the anesthetic safety checklist?
- SAFETY CONCERNS COMMUNICATED (airway, breathing, circulation (fluid balance), body temperature, & pain)
- ASSESSMENT & INTERVENTION PLAN confirmed
- ANALGESIC PLAN confirmed
- person assigned to MONITOR patient
What is included in the equipment check prior to anesthetic induction?
- ensure ET tubes/intubation aids are readily available
- monitoring equipment
- anesthesia machine (select appropriate breathing system, perform leak test, check: oxygen, inhalant, CO2 absorbent, waste scavenging)
How do you prepare a patient for anesthetic induction?
- venous access - catheter placement
- stabilize hemodynamically instable patients
- check HR, pulse quality, & respiratory rate
- connect monitoring equipment (appropriate for disease condition)
- pre-oxygenation: reduces risk of hypoxemia
- quiet enviro
How do you induce anesthesia in a dog and drugs used?
- propofol, alfaxalone, ketamine/diazepam
- administer to effect
What do we not want to do to induce anesthesia in dogs anymore?
mask induction w/ isoflurane or sevoflurane
How do you induce anesthesia in a cat and drugs used?
- propofol, alfaxalone, ketamine/diazepam
- administer to effect
What do we not want to do to induce anesthesia in cats anymore?
mask/chamber induction w/ isoflurane or sevoflurane
What are the ABCs of Anesthesia Induction?
- Airway (intubation, secure tube, inflate cuff)
- Breathing (auscultation for bilateral lung sounds while manually ventilating, check for spontaneous ventilation)
- Circulation (auscultation of heartbeat)
- Depth & Drugs (assess depth of anesthesia, turn on vaporizer)
- Equipment (blood pressure, eye lube very last on list (lube prior to induction))
- Fluids
What should you check on an ET tube prior to use?
- check tube for patency
- check cuff for leaks
What should you remember about ET tube intubation?
- have multiple ET tube sizes available
- laryngoscope, tie, cuff syringe
- pre-measure ET tube length (incisor teeth to thoracic inlet)
What is the technique to intubate a dog?
- can be performed in sternal, lateral, or dorsal
- apply slight coating of lube (improves cuff’s ability to seal)
- open the dog’s mouth, pull tongue forward gently
- straighten head & neck, extend tongue
- put tip of laryngoscope blade on base of tongue, NOT on epiglottis
- insert ET tube under visualization
- inflate cuff while checking for leaks
- secure tube
How do you intubate a cat?
- more difficult than dog: small oropharynx & prone to laryngospasm
- local anesthetic (lidocaine) useful to prevent laryngospasm (lidocaine spray or lidocaine neat 2%)
How do you confirm endotracheal intubation?
- direct visualization (use laryngoscope)
- rebreathing bag
- chest excursions
- palpation of ONE trachea below the larynx
- capnograph
- GOLD STANDARD: auscultation of both sides of the animal’s chest during manual ventilation
What does A stand for in the ABCs of anesthesia induction?
Airway establishment
- intubation
- securing the ET tube
- inflation of the ET tube cuff
- confirmation of endotracheal intubation
What does D stand for in the ABCs of anesthesia induction?
Depth & Drugs
- check depth of anesthesia (eye position, palpebral reflex, jaw tone)
- based on patient’s depth, turn on vaporizer
What does E stand for in the ABCs of anesthesia induction?
Equipment
- apply monitoring equipment
- doppler 1st: audible signal
- monitor blood pressure
- assess patient
- adjust vaporizer setting
What does F stand for in the ABCs of anesthesia induction?
Fluids
- correction of normal ongoing fluid losses
- support of cardiovascular function
- countering of potential negative physiologic effects
- maintaining patent IV catheter
What fluid rate should be used during anesthesia?
New guidelines:
- Cats: 3 mL/kg/hr
- Dogs: 5 mL/kg/hr
old way of 10 mL/kg/hr is NOT evidence based
What is important about the recovery/postoperative period?
- CRITICAL PHASE OF ANESTHESIA
- 47% (dogs) & 60% (cats) of all anesthetic related deaths are w/in 1st 3 hours of recovery
- continued monitoring & patient support is important
What should you remember about extubation in small animals?
- after dental surgery check the oral cavity for fluid
- dont untie the tube until patient has reached the final recovery spot
- ET-tube cuff should not be deflated until just before extubation
When do you extubate dogs?
on return of swallowing reflex
When do you extubate cats?
- cats need to be extubated sooner than dogs
- on return of good palpebral reflex or ear flick reflex
- prone to laryngospasm or laryngeal edema
What is the optimal recovery time?
w/in 10 to 30 mins of the end of the anesthesia
What are common complications during anesthetic recovery?
- emergence delirium
- dysphoria
- pain
- delayed recovery
During recovery, when should patients be closely observed until?
until they are alert, normothermic, & ambulatory
How can you ensure patient comfort during anesthetic recovery?
- limit environmental stress (noise, bright lights)
- prevent hypothermia
- prevent urinary bladder distension
- assess pain & provide adequate pain management
How can you provide supportive care during anesthetic recovery?
- oxygen
- fluids
- heating
- eye lube
