Perioperative Pain Flashcards
What affects the success of anesthesia?
- care of animals perioperatively —> reduce stress and anxiety
- use of multimodal techniques
- comfort of staff with agents and techniques
- minimization of down time (inhalant or deep conscious sedation)
- surgical speed, efficiency, technique, and tissue handling
Why are pain, inflammatory, and anxiety relief so important?
allows reduced general anestehsia usage (decreased MAC), which decreases perioperative mortality/morbidity
What are 7 immediate detrimental effects of acute pain?
- increased metabolic rate
- increased sympathetic tone
- increased cardiac workload
- diminished pulmonary function
- decreased GI blood flow
- increased platelet aggregation
- increased perioperative morbidity and mortality
What surgeon has an extensive bibliograpgy on perioperative medicine?
Henrik Kehlet —> reported incidence of patients with chronic pain states and associated surgical disease
What 2 effects does pain have on long-term outomes?
- general anesthesia and surgery activate endocrine state of catabolism - stress response
- tissue injury can result in profound effects on patient’s local healing and overall immune function (inflammation)
What are 7 delayed effects of uncontrolled pain? What do they result in?
- increased incidence of arrhythmias
- GI stress ulceration/translocation
- increased venous stasis = thromboembolism potential
- reduced organ function
- poor wound healing
- immunosuppression
- chronic pain states
increased long-term morbidity and mortality
What is pre-emptive analgesia? What are 2 results?
analgesics given prior to surgical procedure and continuing during maximal expected pain intensity
- less post-op meds required
- less total pain - post-op, chronic
What are 2 reasons that multimodal analgesia is recommended?
- allows for the use of lower doses of each individual drug
- fewer side effects postulated
What newer approach is used for perioperative pain?
- true premeds to address pain, inflammation, and stress
- common patient comfort
- defined anesthetic and surgical plan
- less reliance on induction and gas anesthesia
What 5 things does premedication provide?
- analgesia
- post operative nausea and vomiting prevention
- sedation
- anxiolysis
- muscle relaxation
(benefits must continue through “insult” - post-op meds still necessary!)
How are most premedications given?
- IM: quads
- IM and IV
- IV: obese patients
When is oral and transmucosal administration able to be used for premedication?
ORAL - with enough time for absorption (night prior)
TM - last resort or pre-hospital entrance for severe anxiety
How should the timing of giving premeds before induction be done? What is done for stressed animals?
- very anxious patients and most electives are given hours before induction
- brachycephalics, ill, fragile, neuro, and obese patients are given minutes before induction
crazy, anxious, aggressive = give premeds, then catheterize
(calmer patients can be catheterized first)
What is Recuvyra?
transdermal fentanyl solution given as a one-time premed for moderate surgical pain
(octyl salicylate and isopropanol allow for concentrations within stratum cornea)
Why are opioids a mandatory part of premedications? What 4 effects do they have?
best analgesics that are the first line for acute and severe pain regardless of ASA status
- cardiovascularly soothing
- respiratory pattern improvement (unless potent IV fentanyls used)
- improved post-op hemodynamics
- some sedation, depending on species
What are the best options for opioids as premedications?
- pure Mu agonists
- longer acting meds, like hydromorphone, morphine, and oxymorphone
What antiemetics are coupled with opioids? What 2 opioids is this not necessary for?
- neurokinin antoagnoist (Maropitant)
- Metclopramide
- Ondansetron
oxymorphone and methadone
What are 11 downfalls to opioid usage?
- no inflammatory or stress relief
- narcosis
- ileus
- nausea
- inappetence
- urinary retention
- carbon dioxide non-responsiveness
- mild bradycardia
- immunosuppression
- opioid hyperalgesia (monotherapy)
- tumor metastasis and angiogenesis
In what 3 ways can the downfalls of opioids be avoided?
- combine the with a solid sedative (Ace, Dex, Midaz)
- do not administer them too frequently or too long
- always give them with a steroid or NSAID (carprofen, meloxicam)
Why are alpha agonists commonly used in premedications? What is its most important effect?
- great sedatives, muscle relaxants, and analgesics
- potent compared to opioids
vasoactive - assists in hemostasis control and BP maintenance
What are 4 caveats to the use of alpha agonists in premedications?
- extremely potent - require mini or micro doses
- cardiovascularly evident with reduced CO
- reduced need for induction and inhalants
- require hemodynamic physiology primer
What are the 4 general classes of perioperative anti-inflammatories?
- steroids
- NSAIDs
- local anesthetics: Lidocaine, Bupivacaine
- physical medicine: light therapy, transcutaneous electrical nerve stimulation, cryotherapy
What is the mechanism of NSAIDs like? What 5 effects do they have?
decreases prostaglandin production
- anti-inflammatory
- analgesic
- antipyretic
- anti-neoplastic and anti-angiogenic
- non-dependence
What are 5 contraindications for the use of NSAIDs?
- bronchospasm
- coagulopathy
- late-term pegnancies
- hepatic and renal failure
- severe GI disease
Why are steroids/NSAIDs used in premedications?
inflammation is a structural and functional disease tht quickly escalates by existing problems and opioids/alpha agonists do not treat it (opioids add to it!)
What are the 2 rationales for NSAID usage preoperatively? What additional effect does Carprofen have?
- able to be combined with other agents to produce better pain control
- have a profound effect on reduction of inflammation post-surgically
MAC sparing effect
How is Acetaminophen used in premeds? In what 2 ways does it compare to NSAIDs? What is required?
good analgesic and antipyretic in dogs (TOXIC IN CATS)
- not an anti-inflammatory
- does not cause GI ulceration, renal disease, or platelet dysfunction
proper glutathione for hepatic function
In what 6 situations are steroids used over NSAIDs?
- brachycephalics
- disc disease
- laryngeal surgery
- CNS surgery
- endotoxemia
- renal disease
(Prednisone, Prednisolone)
How does transdermal Lidocaine work? In what 2 situations is it extremely helpful?
topical Lidocaine able to penetrate intact skin
- superficial applications
- canine stifle injury if effusion is significant
Other than a locoregional block, what effect does Lidocaine have?
increases wound healing
- potent anti-microbial
- reduces local inflammation
- reduces ischemia-reperfusion injury
What are 6 caveats to CRIs?
- try to reduce amount of morphine post 6 hours
- lidocaine can result in inappetence and nausea
- a little dexmed makes a big difference
- ketamine encourages better cardiac output
- switch it up every 12-24 hours
- have post-op rates 25-30% of intraop rates
What types of medications are used as rescues? What are 6 examples? How should anesthesia machine settings be altered?
analgesics
- opioid used in premed
- Fentanyl
- Ketamine
- Dexmedetomidine
- Lidocaine
- Propofol
turn up oxygen flow rate and mildly increase vaporizer
What immediate and first 24 hour analgesia are recommended?
IMMEDIATE - microdose Dexmedetomidine, opioids
FIRST 24 HOURS - repeat opioids q 6-12 hours, couple it with Acepromazine and Dexmedetomidine half IV and half IM
When can patients be transitioned to oral medications following surgery? What are some examples?
once eating
- Oxycodone
- NSAIDs
- steroids
- Trazadone
- Gabapentin
- muscle relaxants
Why is Tramadol carefully used perioperatively?
literature suggests it has sufficient analgesic effects, but it seems in practice that may not have enough effect by itself or at all
Pure mu receptor opioids provide excellent acute pain relief regardless of signalment and problem list and they can also cause:
a. urination
b. absolute sedation
c. hypothermia
d. reduced emesis
e. bradycardia
E
All of the following are considered “rescues” for intraoperative pain except:
a. Ketamine 0.5-1 mg/kg
b. Hydromorphone 0.02-0.05 mg/kg
c. Fentanyl 2-5 mcg/kg
d. Thiopental 10 mg/kg IV
e. Lidocaine 2-3 mg/kg
D
Midazolam is practically a poor sedative but its safety is linked to all of the following except:
a. no effect on golgi tendon activity
b. no effect on systemic vascular resistance
c. no effect on cerebral blood flow
d. no effect on cardiac output
e. no effect on CNS neuronal activity
A
Which of the following is a similar analgesic mechanism between opioids and alpha two agonists?
a. act at beta receptors in tiny blood vessels
b. noth work on the mu opioid receptor
c. increase sodium grdients
d. act at same G protein synergistically
e. intersct with Ach receptor
D
All of the following are differentials for intraoperative tachypnea except:
a. too deep inhalant plane
b. hypercapnia
c. having to urinate
d. legs pulled too tightly in an older dog restrained on the surgery table
e. pain
A
Which of the following should not be added to an epidural?
a. Morphine
b. Bupivicaine
c. Lidocaine
d. saline
e. Cefazolin
E
True or false: Transdermal fentanyl can be used for premedication in cats.
True
All of the following except one are consequences of inadequate pain control:
a. decreased cardiac work
b. increased platelet aggregation
c. decreased GI blood flow
d. increased sympathetic vascular tone
e. diminished pulmonary function
A
Serotonin syndrome can be a consequence of prescribing tramadol when an animal is currently on all of the following drugs except:
a. Metclopramide
b. Clavamox
c. Amitriptyline
d. Ondansetron
e. Fentanyl
B
Premedication is used for all of the following except:
a. anxiolysis
b. provide preoperative and intraoperative sedation
c. muscle relaxation
d. limitation of appetite
e. analgesia
D
