26 – Small Animal Review Flashcards
Overview: Steps of Anesthesia
- Pre-anesthetic evaluation and patient preparation
- Pre-anesthetic medication
- Anesthetic induction
- Maintenance and monitoring
- Recovery
Pre-anesthetic evaluation and patient preparation
- Fully examination: age, temperament, breed
- Medical history
- Basic hematology
What to look at or do for older and sick patients in a pre-anesthetic evaluation?
- Complete blood count, serum chemistry, urinalysis
o On basis of physical exam and history - Radiograph thorax (trauma or respiratory problems)
- ECG, echocardiography
If you need to delay anesthesia, you will do that until
- Further assessment is performed
- Patient is stabilized
- Anesthetic risk is established
What do you need to communicate with you client prior to anesthesia?
- Anesthetic risk
- Set expectations
- Patient preparation starts at home!
What are some prehospital anxiety drugs (2 hours prior to drop off)?
- Trazadone
- Gabapentin
Patient preparation: food and water
- Allow free access to water
o Care with old animals and animals with increased fluid requirements - Recommend fasting before anesthesia
o Young animals: require SHORTER fasting times
What is the recommending fast time for 6-16 weeks and older than 16 weeks?
o 6-16 weeks: 4 hours
o Older than 16 weeks: 6-8 hrs
Anesthesia protocol: 5 things to consider
- Physical exam
- Age
- Temperament
- Surgical procedure
- Clinical setting
Anesthesia protocol: premedication, induction, maintenance, post operative pain management
- Premedication: Sedative + opioid
- Induction
- Maintenance: inhalant +/- opioid +/- local anesthetic
- Post operative pain management: NSAID, opioid
What are the aims of premedication?
- Sedation and anxiolysis (fear free)
- Facilitate animal handling
- Balanced anesthetic technique
- Analgesia
- Smooth and quiet recovery
Opioids for premedication:
- Hydromorphone
- Methadone
- Butorphanol
- Buprenorphine: slower onset time
What are the 3 sedatives you may combine with your opioids for premedication?
- Acepromazine
- Dexmedetomidine
o *Don’t co-administer with an anticholinergic (goes against the reflex bradycardia) - Midazolam
What are the 2 anticholinergics you may use for premedication?
- Atropine
- Glycopyrrolate
What is the standard premedication protocol for calm dogs?
- Acepromazine OR dexmedetomidine
- Hydromorphone
What is the standard premedication protocol for excited, agitated dogs?
- Acepromazine
- Dexmedetomidine
- Hydromorphone
- *if aggressive=add ketamine
What is the standard protocol for premedication in cats?
- Dexmedetomidine
o Range based on age and temperament of cat - Hydromorphone
Heavy sedation of cats: “kitty magic”
- Dexmedetomidine
- Ketamine
- Butorphanol
‘kitty magic’
- For more reliable sedation=use ketamine based protocol
- Provides general anesthesia for invasice short procedures
- Monitor paient!
- Provide life support!
What should you not use in young and healthy patients as a premedication?
- Midazolam
o Causes excitement!
o Could use flumazenil to reverse excitement but will NOT provide sedation - *use in animals with hypertrophic cardiomegaly
Which drugs would help you to achieve sedation in a young and healthy cat for a neuter if given midazolam and is excited?
- Dexmedetomidine (IM): may use a higher dose to override excitement
- Alfaxalone (IM): would need a higher dose
- Ketamine (IM): would need a very HIGH dose and it would last longer
o Can use for cat neuters but at lower doses (combination)
Equipment check for anesthetic induction
- Ensure ET tubes (3 sizes) and intubation aids are readily available
- Monitoring equipment
- Anesthesia machine
o Select appropriate breathing system
o Perform leak test
o Check: O2, inhalant, CO2 absorbent, waste scavenging
Patient preparation for anesthetic induction
- Venous access: catheter placement
- Stabilize hemodynamically instable patients
- Check HR, pulse quality and RR
- Connect monitoring equipment
- Pre-oxygenation (reduce risk of hypoxemia)
- Quiet environment
What can you use for induction of anesthesia in dogs and cats?
- Propofol
- Alfaxalone
- Diazepam or ketamine
- Mask/chamber induction: isoflurane or sevoflurane=MOVE AWAY FROM IT
- *administer toe effect
What are the ABCs of anesthesia induction?
- Airway
- Breathing
- Circulation
- Depth
- Equipment
- Fluids
A-airway establishment (intubation)
- Endotracheal intubation
- Securing the ETT
- Inflation of ETT cuff
- Confirmation of ET intubation
Endotracheal intubation
- Check prior to use
- ET for patency and cuff for leaks
- ‘Murphy Eye’
- Have multiple sizes available
- Laryngoscope, kling, cuff syring
- *Pre-measure ET tube length (incisor teeth to thoracic inlet!)
What is the intubation technique for a dog?
- Can be performed in STERNAL, lateral or dorsal
- Apply slight coating of lube (improves cuff’s ability to seal)
- Open dog’s mouth, pull tongue forward gently
- Straighten head and neck, extend tongue
- Put tip of laryngoscope blade on base of tongue (lower the epiglottis), NOT on epiglottis
- Insert ET tube under visualization (with dominant hand)
- Inflate cuff and check for leaks
o *avoid over inflation of ET-tube cuff - Secure tube
Intubation of cat
- More difficult than dog
o Small oropharynx=prone to laryngospasm - Local anesthetic (lidocaine) useful to prevent laryngospasm
o Lidocaine spray: metered dose 12mg
o Lidocaine neat 2% (for smaller patients, 2mg per 0.1ml) - Size 3-4 should work
How can you confirm ET intubation?
- Direct visualization (use laryngoscope)
- Rebreathing bag
- Chest excursions
- Palpation of ONE trachea below the larynx (if in esophagus=feel 2)
- Capnograph
- *GOLD STANDARD: auscultation of both sides of animal’s chest during manual ventilation
B – breathing
- Auscultation for bilateral lung sounds while manually ventilating
- Check for spontaneous ventilation
o If not=assist
C – circulation
- Stethoscope over heart for heart beat
- BOTH SIDES
D – depth and drugs
- Check depth of anesthesia
o Eye position
o Palpebral reflex
o Jaw tone - *based on patient’s depth=turn on vaporizer
E – equipment
- Apply monitoring equipment
- Doppler first: audible signal
- Monitor BP
- Assess patient
- Adjust vaporizer setting
F – fluids
- Correction of normal ongoing fluid losses
- Support of CV function
- Countering of potential negative physiologic effects
- Maintaining patent IV catheter
What are the new fluid guidelines during anesthesia for dogs and cats?
- Cats: 3ml/kg/hr
- Dogs: 5ml/kg/hr
Recovery: Postoperative period
- *Critical phase of anesthesia
- 47% (dogs) and 60% (cats) of all anesthetic related deaths within first 3 hrs of recovery
- Continue monitoring and patient support
- *still have the effects, but no more O2
Exudation in small animals
- After dental surgery: check oral cavity for fluid
- Don’t untie tube until patient has reached final recovery spot!
- ET-tube cuff should NOT be deflated until just before extubation
Dogs extubation
- On return of swallowing reflex
Cats extubation
- Need to be extubated sooner
o On return of good palpebral reflex and ear flick reflex - Prone to laryngospasm or laryngeal edema
What is the optimal recovery time?
- Within 10-30mins of end of anesthesia
- *patients should be CLOSELY observed until they are:
o ALERT
o NORMOTHERMIC
o AMBULATORY
What are some common complications of recovery?
- Emergence delirium
- Dysphoria
- Pain
- Delayed recovery
Recovery: ensure patients comfort
- Environmental stress (noise, bright lights)
- Hypothermia
- Urinary bladder distension
- Pain assessment and adequate pain management
What is some supportive care during recovery?
- Oxygen
- Fluids
- Heating
- Eye ointment
