anaesthesia crises

2/9/2021

1

Anaesthesia Crises

Dr. Erik Hofmeister

Outline

• Common problems • Crisis philosophy • Actual crises

Waking Up

• Anesthetic concentration too low • Not connected to circuit • Oxygen not on • Vaporizer not on

• Vaporizer empty

2/9/2021

hyperthermia, acidosis, endotoxemia

2

Approach to Waking Up

• Immobilize patient, prevent from chewing tube

• Re-anesthetize patient – Injectable, inhalant

• Is patient connected? Gasses on? Vaporizer full?

Waking Up Management

• Increase gas concentration – Increase O2 flow – Increase vaporizer setting – Increase ventilation – Avoid O2 flush valve!

• Balanced anesthetic technique – Add opioid, sedative

Tachycardia • Pain • Getting light • Hypercarbia • Hypoxemia • Drugs • Hypovolemia

Anemia, cardiac disease, arrhythmias, hypoglycemia,

2/9/2021

• Machine fault

3

Approach to Tachycardia

• Is the patient comfortable? Is it asleep? • Is the patient’s volume OK? • Is the patient on relevant drugs? • Is the patient hypercarbic/hypoxemic?

• Is it too high? Symptomatic treatment needed?

Tachycardia Treatment • Painful: hydromorphone 0.05mg/kg IV • Light: increase gas, diazepam 0.2mg/kg IV • Hypovolemic: Test bolus of 1 hour’s fluids • Drugs: stop CRIs and watch • Hypercarbia: ventilate • Hypoxemia: see hypoxemia • Symptomatic: B-blockers

– Esmolol, propranolol

Hypercarbia

• Ventilator error • User error • Endobronchial intubation • Increase metabolism

2/9/2021

4

Approach to Hypercarbia • Are the ventilator settings and inspiratory

pressure appropriate? • Is the patient’s chest moving normally? • Is the ventilator attached correctly? Are

there any leaks? • Is there good air flow on both sides of

chest? • Is patient hyperthermic, red, tachycardic,

or had an abrupt increase in ETCO2?

Hypocarbia

• Cardiac arrest • Ventilator error • User error • Hypothermia

• Machine fault • Nonrebreather

Approach to Hypocarbia

• BP/HR!!!!! • Are ventilator settings appropriate? Check

inspiratory pressure • Check monitor/machine

2/9/2021

– Aminophylline 5mg/kg

5

Hypoxemia

• Decrease inspired O2 • Hypoventilation • Right to left anatomic shunt • V/Q mismatch

• Diffusion impairment

Approach to Hypoxemia

• Obtain blood gas • Check machine • Is patient hypoventilating? If so, how

severely? • Did airway pressure or ventilator settings

change recently- change in compliance? • Surgeons doing anything funny?

Hypoxemia Treatment

• Make sure getting O2 • Increase tidal volume (peak inspiratory

pressure to 25-30 cm H2O if needed) • Change position (dorsal to lateral, tilt head

up, lateral to sternal) • Bronchodilators

2/9/2021

– Ephedrine 60 μg/kg

6

Hypotension

• Bradycardia • Poor venous return • Poor contractility • Vasodilation

Approach to Hypotension

• Is patient bradycardic? • Is patient volume depleted? • Does patient have drugs/disease which

would impact contractility or vasodilation? – Inhalants, endotoxemia, acepromazine,

thiopental, propofol, cardiac disease, lidocaine/bupivacaine OD, morphine IV, etc.

Hypotension Treatment

• Bradycardia – give atropine, glycopyrrolate • Volume depleted – give fluid bolus of 1

hour’s fluids • Poor contractility – give inotrope

– Dobutamine/dopamine 5μg/kg/min

2/9/2021

7

Vanished Doppler

• Doppler fault • Technical fault – slipped probe • User error • Cardiac arrest

• Closed pop-off valve

Approach to Vanished Pulse

• Patient alive? • Pop-off open? • Doppler on/volume up? • Probe correct position?

Bradycardia

• Drugs – NMBA reversal drugs, lidocaine, fentanyl,

medetomidine, inhalant OD, etc. • Disease • Hypothermia

2/9/2021

8

Approach to Bradycardia

• Is patient hypotensive? • Is bradycardia rapidly evolving? • Is HR really low?

• Treatment: atropine 0.02mg/kg IV or

glycopyrrolate 0.005mg/kg IV

Hypertension

• Pain • Getting light • Hypercarbia • Hypoxemia

• Drugs

Cardiac disease, arrhythmias, hypoglycemia, hyperthermia, acidosis, endotoxemia

Approach to Hypertension

• Ruleout per tachycardia • Is it too high? • Mechanical error?

2/9/2021

9

Hypertension Treatment

• Treat underlying disease/problem • Symptomatic treatment:

– Increase inhalant anesthesia setting – Administer acepromazine 0.05mg/kg IV

– Administer nitroglycerine or nitroprusside

Prolonged Recovery

• Drug OD • Hemorrhage • Cerebral ischemia • Hypoglycemia

• Liver disease • Renal disease • CNS disease • Young/old/thin/debilitated

Approach to Prolonged Recovery

• Was there profound hypotension during anesthesia? – Assess pupils, vision – Reverse drugs – Treat for cerebral edema- mannitol 0.5g/kg IV

• Check PCV/BG • Reverse drugs

– Naloxone 0.01mg/kg IV – Flumazenil 0.01 mg/kg IV

2/9/2021

10

Hypothermia

• Prolonged anesthesia • Abnormal heat production • Abnormal temperature regulation (CNS

disease, endotoxemia)

Approach to Hypothermia

• Concurrent problems? (bradycardia, hypotension, prolonged recovery) – Treat aggressively

• Prevention is easier that treatment

• Slow rewarming better than rapid • Warm air blower, radiant heat lamp, warm

water blanket, towels

Hyperthermia

• Heat stroke (exogenous heat- OD from forced air warming, heat lamp, surgery light)

• Febrile (disease-based) • Malignant hyperthermia

2/9/2021

11

ght not filled

Clerk estimated weight t engine had

ong brakes

Approach to Hyperthermia

• Concurrent abrupt increase in CO2/HR? – Malignant hyperthermia likely

• Turn off warming devices • Treat underlying disease • Active cooling if necessary (careful if

under GA)

Crises

Crises

Wei

La wr

s

Curve on Duffy St

2/9/2021

12

ght not filled

Clerk weighed ars t engine had

ong brakes

itten ntubated ithout uarded tube

T tube xchanged ith rigid stylet tten bronchi

agile

Iatrogenic Arrest

Anaesthetic Crises

• Inadvertent drug administration • Loss of airway • Iatrogenic cardiac arrest

– Closed pop-off valve • Profound or persistent hypotension • Biting animal

Wei

c

Curve on Duffy St

s

La wr

K i w g

E e w Ki

fr Tension pneumothorax not diagnosed

2/9/2021

13

Crisis Management

• DON’T PANIC • Get help • Figure out who’s in charge • Start to do what you can

Inadvertent Drug Admin

• Withdraw what you can • Precipitate if possible • Solution to pollution is dilution • Reversal of drugs if necessary/possible

– Naloxone 0.01mg/kg – Flumazenil 0.01mg/kg

– Doxapram? 1.25 mg/kg • Be honest with owner/team

Drug Overdose

• Step A: Determine problem exists • Step B: Determine how severe problem is • Step C: Drug reversible? • Step D: Supportive care

2/9/2021

14

Loss of Airway

• Give oxygen by other methods • Attempt orotracheal intubation

– Sylet, multiple lights, rigid ET tube • Needle tracheotomy • Wire stylet through trachea • Tracheotomy

Iatrogenic Cardiac Arrest

• CHECK MACHINE • Check syringes before injection • Be prepared • Begin CPCR efforts

– ABCDE • When in doubt, turn off gas

Profound Hypotension

• EARLY RECOGNITION • DON’T muddle with technology • Turn off gas • Administer fluids, inotropes, volume

expanders (hetastarch, hypertonic saline) • Correct underlying problems (acidosis,

hypocalcemia) • Tell surgeons to hurry it up

2/9/2021

15

Biting Animal

• Let animal go if possible – don’t get bit! • Get towel/rabies pole/squeeze cage • Sedate if possible according to disease • Protocols:

– Morphine 0.5mg/kg, diazepam 0.5mg/kg, ketamine 10mg/kg, atropine 0.02mg/kg

– Morphine 0.5mg/kg, medetomidine 20μg/kg

Crises Debriefing

• What happened? • How did it happen? • Why did it happen? • How do we prevent it from happening

again?

NOT: Whose fault?

Crisis Causes

• Rushing • Unskilled/unknowledgeable • Patient

2/9/2021

16

Summary

• Learn common differentials • Figure out what’s going on and why • Begin to treat appropriately • If no response- change treatments! (see

House MD)

Summary

• Crises occur as a synergy of events • Crises can be prevented or mitigated by

education, preparation, and slowing down • In a crisis, take a deep breath, get help,

figure out who’s in charge, and begin

Communicating Anesthesia Risk to Clients

Dr. Erik Hofmeister

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 2 Learning Objectives

• Participants will understand risk factors for anesthesia• Participants will know risk rate for adverse events• Participants will understand concerns clients have• Participants will be able to communicate with clients about the risk

of anesthesia

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 3 Outline

• Introductions• Literature review – anesthesia risk factors• Client concerns• Effectively allaying concerns• Clinical recommendations

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Introductions

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 5 Participant Poll

• What is your primary role/background?• Private practice veterinarian• Private practice technician• Specialty practice veterinarian• Specialty practice technician• Other

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Has a client expressed concern to you about anesthesia in the past month?

• Yes• No

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Literature Review

• 1.7 in 1000 dogs• 2.4 in 1000 cats• ASA Status

• 0.5 in 1000 dogs vs. 13 in 1000 dogs• 1.1 in 1000 cats vs. 14 in 1000 cats

• Most commonly postoperative

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 8 Literature Review

• Cats• Emergency• Smaller size <2kg• Larger size >6kg• Intubated• IV fluids

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 9 Literature Review

• Dogs• Emergency procedure• No physical exam• Underweight• Anemia• (Xylazine)

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Literature Review

• Age?• Equivocal – some studies indicate yes, others no• May be due to concurrent illnesses captured by other variables (ASA)• Occult disease/conditions

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• What do clients express most concern with regards to anesthesia?• Death• Pain• Vomiting/nausea• “Unsettled”/behavioral• Drug reactions• Generalize/uninformed• Other

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 12 Client Concerns

• Death• Normal, healthy patients particularly unlikely• Unhealthy, emergency patients more likely (but still ~1 in 100)• If unexpected, can be most unsettling

• Pain• Clients assume patient will be comfortable• Some may worry about this in deciding whether to do a procedure or not• Postop pain often unwitnessed by client or misidentified

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Client Concerns

• Vomiting/nausea• Serious problem in human anesthesia – if client had surgical procedure, may

relate• If patient has a history of GI disease, may express concern

• Unsettled/behavioral• Worried about separation from owner• History of poor recovery from anesthesia• History of abnormal behavior after discharge

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Drug reactions• “Sensitive” to anesthesia• 2008: Breeds with a sensitivity to anesthesia that were mentioned by > 30%

of Web sites• A friend told them “x” or their breeder told them “y”• My concerns:

• Sighthounds with thiobarbiturates (no longer used)• Boxers with acepromazine• MDR1 mutation dogs with acepromazine or butorphanol• Brachycephalic breeds• History of a problem

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Generalized• “I just worry” or “I heard anesthesia is dangerous”• Asking questions may help improve understanding• Often worried because of unknown – providing information helpful

• Age• “I’ve heard it’s not safe to anesthetize old dogs.”• Share experience managing these cases• Evidence is not conclusive that this is true

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Allaying Concerns

• Be proactive• Explain your process for managing pain and monitoring patient• Sedation, analgesia, induction, monitoring, recovery

• Solicit questions• Consider “what questions do you have” vs. “do you have any questions?”• Can ask specifically about anesthesia, “what questions do you have about

anesthesia for Fluffy?”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 17 Allaying Concerns

• Unsolicited questions• May interrupt your ‘flow’• “I understand you have questions about anesthesia. Let’s discuss the rest of

Fluffy’s care and we will talk about that at the end.”

• What if you don’t have answer?• “That’s a good question. We don’t routinely give anti-nausea medications,

because we haven’t experienced that as a problem. I will talk to my colleagues and get back to you about this.”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Be attentive and listen• Reflective listening

• “I understand you’re worried about Fluffy’s pain.”• “So last time she went under anesthesia, she wasn’t right for 3 days.”

• Can ask for clarity• “What are you most worried about with Fluffy’s anesthesia?”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Allaying Concerns

• Validate, do not ‘blow off’• “I know how worried you are about Fluffy not making it through anesthesia. I

am not very worried, because she is a healthy dog and we have a technician dedicated to monitoring her throughout. Healthy dogs have a very low risk of death- only 1 in 2,000. If she has problems, we will know about them immediately and take steps to correct them.”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Validate• “I know how worried you are about Fluffy not making it through anesthesia.

It is concerning, because she has a serious disease and that makes anesthesia more challenging. With sick dogs, the chances are about 1 in 100. However, we have to proceed to try and make her better. We have a technician dedicated to monitoring her throughout. If she has problems, we will know about them immediately and take steps to correct them. Nonetheless, it is possible she will not make it despite our best efforts, but we will do everything we can for her.”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• More validation• “I understand the breeder said not to use ketamine with this line. We have

other drug options available, so will be able to avoid it. I will make a note in the chart.”

• “I understand the breeder said not to use ketamine with this line. Ketamine is a routine part of our protocol and it is the one we are most comfortable and familiar with. I feel it is best to maintain our typical routine, as that will be the safest for Fluffy. If she experiences any problems with it, we will manage them. We routinely use ketamine in Fluffy’s breed without problems.”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Allaying Concerns

• Be careful to avoid jargon – use lay terms• “Sedate” rather than “premedicate”• “Transition to anesthesia” or “knock out” rather than “induce”• “Manage pain” rather than “analgesia”• “Recover from anesthesia” rather than “extubate”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Client is being too demanding or difficult• Reflective listening• Validate concerns• Explain rationale for choices• Explain need for anesthesia• Decide how important the issue is

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________


• Check with client to see if explanation/discussion has met their expectations

• Can appeal to ‘higher power’• Clinic policies

• “I’m sorry the clinic policy is to not have clients present for the start or end of anesthesia.”

• Organizations• “Well the American Veterinary Dental College recommends animals be under general

anesthesia for cleanings, because that’s the only way to do a proper dental cleaning.”

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Clinical Recommendations

• Proactively engage clients about anesthesia• Validate feelings/concerns• Provide information• Call local anesthesiologist for backup

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 26 Learning Objectives

• Participants will understand risk factors for anesthesia• Participants will know risk rate for adverse events• Participants will understand concerns clients have• Participants will be able to communicate with clients about the risk

of anesthesia

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

Slide 27 Summary

• Participants will understand risk factors for anesthesia• Sick, emergency, small, +/- old

• Participants will know risk rate for adverse events• 1:2000 healthy, 1:100 sick

• Participants will understand concerns clients have• Death, pain, nausea, behavior, drug reactions, generalized

• Participants will be able to communicate with clients about the riskof anesthesia

• Validate, explain

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

___________________________________

2/9/2021

1

Medical Error Dr. Erik Hofmeister

Outline

• Why errors occur • Types of errors • Strategies to minimize errors

Learning Objectives

• Understand why people make errors • Describe strategies to minimize error • Describe how to handle errors

2/9/2021

2

Why Do Errors Occur?

• To: 22333

• Text: 10257 “your text here”

Why Errors Occur

• We are not rational actors • Placebo effect • Financial motivation • Endowment effect • Cognitive biases • Expectations – vinegar in beer

• Excellent at pattern recognition

Caveat

2/9/2021

3

Et by Lion?

• On savannah, hear a rustle in the grass • Is it a lion? • Is it the wind? • Do you run? • Do you hang out?

Et by Lion

Lion Wind

Run Survive Survive

Hang Out Die Survive

Et by Snake?

• On savannah, see a funny object • Is it a snake? • Is it a stick? • Do you run? • Do you hang out?

2/9/2021

4

Et by Snake

Snake Stick

Run Survive Survive

Hang Out Die Survive

Pattern Recognition Problem

• More likely to see and remember ‘hits’ and forget ‘misses’ • Evolved to find patterns whether meaningful or not

Ca y u rea t is?

2/9/2021

5

You a e not r adin g th s

Pattern Recognition Problem

• Rely on pattern recognition • What if you have never

seen the pattern before? • Lidocaine OD • Bird hyperthermia

Types of Errors

• What type of error do you worry about the most?

2/9/2021

Types of Errors

6

• Accidents • Unintended Actions

• Slips • Lapses

• Intended Actions • Mistakes

Types of Errors

Types of Errors

2/9/2021

Types of Errors

7

• Active Errors

• Giving wrong drug to patient

• Latent Errors • Drug vials of the same color

Types of Error

• System Accident • Highly complex • Tightly coupled • Cascading failures • Opaqueness

Types of Error

• Swiss Cheese Model • Complex systems have redundancy • Series of problems required for catastrophe • Organizational influences • Supervision • Preconditions • Specific acts

2/9/2021

8

itten ntubated ithout uarded tube

T tube xchanged ith rigid stylet ten bronchi

agile

Types of Error

Types of Error

Types of Error

K i w E g e

Kit w fr

Tension pneumothorax not diagnosed

2/9/2021

9

Types of Error

• Analysis of 13 anesthetic CPA events • Patient = 14

• Looking over the shoulder of the surgeon, I could see one small area of pulmonary tissue that looked like it was normal - it was about the size of a quarter.

• Human = 12 • May have been preventable if more thorough monitoring peri-induction (i.e. ECG) • Took 2 hours of anesthesia time to cutdown to femoral, then went to CT to look for

aberrant coronary vessel, which he had. Then back to IR for balloon. Took long time… • Procedural = 4

• When they removed the bone due to necrosis of esophagus there was a large tear. • Drugs = 1 • Equipment = 1

Types of Error

• Insurance Claims • Cognitive limitations = 51% • Owner contribution to error = 15% • Lack of technical knowledge or skill = 14% • Productivity = 7% • Failure of communication = 5% • Failure of leadership = 4% • Veterinary specific = 4% • Negligence = <1%

Oxtoby C, Ferguson E, White K, Mossop L. We need to talk about error: causes and types of error in veterinary practice. Vet Rec. 2015 Oct 31;177(17):438.

Types of Error

• Spay operations (n=128) • Retained surgical items (n=76) • Hemorrhage (n=67)

2/9/2021

Strategies to Minimize Error

10

• What are strategies to minimize error?

• To: 22333



• First step is to identify/quantify error • Institution specific • Systems errors commonly contribute/cause problems

• Second step is to learn from error • M&M rounds • Voluntary reporting • Non-punitive environment • Confidentiality


• Critical Incident Technique • Qualitative analysis of what occurred • Useful for describing steps in detail for future remediation

• Root Cause Analysis • Continue to ask “why” until root cause is found

2/9/2021


11

• Changing habits: “We’ve always done it this way” • Accept that errors can and will occur • Contingency plans for anticipated problems • Prepared to seek more qualified assistance • Do not let professional courtesy inhibit checking colleague’s

knowledge (pilot ice on wing example) • Training


• Safety culture • Open • Just • Reporting • Learning • Informed • Flexible and resilient


• Cognitive Forcing • Rule of Three • Checklists • Mnemonics • Structured communication (SBAR)

• Systems walk

2/9/2021


12

• What happened? • How did it happen? • Why did it happen? • How do we prevent it from happening again?

NOT: Whose fault?


• Process • Focus on system, not ‘sharp’ end • Buy in – belief in improvement

Why Do Errors Occur?

• To: 22333


2/9/2021

13

Learning Objectives

• Understand why people make errors • Describe strategies to minimize error • Describe how to handle errors

Conclusion

• Error is intrinsic in human activity • Complex systems make it more likely • Need to learn from errors and take systematic steps to improve

8 0

6 0

4 0

2 0

0

In c

id e

n

2/9/2021

• Implementation

1

Newer Anesthetic Drugs

Dr. Erik Hofmeister

Purpose

• Thinking of trying new drug • Clinicians already using them

– Optimization – Should be using them?

• See what’s on horizon for future

Outline

• Dexmedetomidine • Buprenorphine/Simbadol • Propofol/Propofol 28

• Alfaxalone • Etomidate • Sevoflurane • Nocita

2/9/2021

Dexmedetomidine

• Moderate respiratory depression

2

• Medetomidine introduced late 90s • Used primarily in dogs/cats • Patent was set to expire • Pfizer switched to dexmedetomidine

• Generic medetomidine variably available

Dexmedetomidine

• Agonizes presynaptic α2 receptor • Inhibits release of norepi • Decreases sympathetic outflow in CNS and

periphery • α2:α1 selectivity

– xylazine 160:1

– detomidine 260:1 – Dex/medetomidine 1260:1

Dexmedetomidine

• Profound CV effects – vasoconstriction = increase SVR, increase

afterload – Negative inotrope = decrease contractility – Decrease CO 30-50%

• Reflex bradycardia • Arrhythmogenic

2/9/2021

Dexmedetomidine

– Patients who can’t tolerate opioids

3

• Somewhat expensive – Small volume

• Moderate therapeutic index • Arousable aggression

– Use opioid

• Emesis, ileus

• Depresses insulin release = hyperglycemia

Dexmedetomidine

• Resedation after reversal? • Duration shorter than medetomidine

– 45 min vs. 60-90 min

• Sedative effects not as profound as med?

Dexmedetomidine

• Excellent sedation – Good for young, energetic patients

• Reversible – Good for short out-patient procedures

• Excellent analgesia – Patients still painful after opioids

2/9/2021

4

Dexmedetomidine

• Use – 5-10 mcg/kg IM or IV

• Summary – Profound CV effects – bradycardia OK – Great sedation/analgesia – Reversible

– Somewhat expensive – Good for healthy outpatients

Buprenorphine

• Recent research in benefits/uses • Used in human medicine in opioid addicts • Partial mu-agonist opioid

– Morphine/fentanyl pure mu-agonist

– Ceiling effect – not best for very painful patients – Binds mu receptor very tightly

– Kicks morphine/fentanyl off

Buprenorphine

• Sedation with higher doses • No real side effects

– No panting, emesis, etc.

• Presently very expensive

2/9/2021

5

Buprenorphine

• Good analgesia – Not as profound as morphine/fentanyl – Better than butorphanol

• Long lasting – 4-8 hours – Longest opioid

– Extended release formulation (Simbadol)

• Controlled class III

– Minimal risk of abuse (dispensing out)

Buprenorphine

• Transmucosal absorption in cats – Good absoprtion from mouth – Easy administration for clients – Can cause some salivation

• Maybe transmucosal in dogs – Make sure get in cheek

– Ingestion not very effective

Buprenorphine

• Use – 0.01 mg/kg SQ/IM/transmucosal/IV – Q4-8h

• Summary – Decent analgesia (OK spay/neuter/wounds) – Relatively inexpensive – Long-lasting – No significant side effects

2/9/2021

6

Simbadol

• Higher concentration (1.8 vs. 0.3 mg/mL) • Higher dose (0.24 vs. 0.02 mg/kg) • Duration ~72 hours

Propofol

• Non-barbiturate anesthetic • Used since 1990s • Effects at GABA, same as Thiopental • No analgesia – need something else

• Hypotension – Vasodilation – Decrease contractility – Not good for CV compromised patients

Propofol

• Respiratory depression – Hypoventilation (increase CO2) – Apnea- need to be ready to intubate

• Oxidative damage with repeat dosing in cats? – Evidence equivocal

• Sometimes painful given IV

– Esp. old catheter

2/9/2021

Propofol

7

• Lipid-soluble – Requires lipid vehicle – Soy-lecithin (white) – Promotes bacterial growth – Should be discarded after being open 6 hours – Refrigerated storage? – Propofol 28 contains benzyl alcohol

• OK for induction • Not OK repeated inductions/CRI in cats

Propofol

• Controlled substance varies • Requires IV access

– Does not cause extravascular necrosis

• Can cause myoclonus – Not a seizure, ride it out

• Relatively narrow TI

– Can overdose

Propofol

• Relatively expensive – Discarded in a day – depends on caseload

• Propofol28 can keep for 28 days

– More expensive than ket/val – Not as expensive as Telazol – Changeover up to caseload

• Rec. full changeover

2/9/2021

Propofol

8

• Rapidly metabolized – Primary indication – Smooth, rapid recovery – Liver dz, bulldogs, short procedures, neonates – Can be used as CRI or repeat boluses

• Use

Propofol

– Induction 4 mg/kg – CRI 12-24 mg/kg/hr

• Summary – CV depression – Apnea – Expensive – Rapid/smooth recovery – Choice depends on caseload

• I prefer ket/val

Alfaxalone

• Steroid anesthetic • Part of Saffan/Althesin in 70s/80s

– Anaphylactoid reactions in cats from carrier – Largely removed from veterinary market

• Now reformulated – Different carrier

– Alfaxalone only (no alfadalone) – NO anaphylactic reactions

• Available in the US

2/9/2021

Alfaxalone

9

• Been used in Australia/NZ for while • Controlled in the US • Some CV depression

– May not be as much as propofol

– Clinical doses seems minimal

• Moderate resp depression

– Some apnea

Alfaxalone

• Cost expensive – Comparable with propofol?

• No analgesia • Recovery can be suboptimal

Alfaxalone • Can be given IM

– Truculent patients – Reptiles

• Rapidly metabolized – Similar to propofol

• Not as rapid recovery

– Can be given repeatedly

• Not labelled for stored use • Maybe better c-sections?

2/9/2021

Alfaxalone

10

• Use – 2-3 mg/kg IV or IM with premed

• Summary – Minimal CV depression – Some resp depression – Cost expensive – Controlled – Can be given IM – Relatively rapid/smooth induction/recovery

Etomidate

• Non-steroid non-barbiturate anesthetic • Affects GABA as per thio and propofol • Used in human medicine since 80s • Universities stock and some clinics acquiring

Etomidate

• No analgesia • Myoclonus

– Unpleasant inductions – Include diazepam or midazolam

• Adrenocortical suppression – Esp. doses above typical induction – Lasts for 8+ hours – Bad esp. in septic patients

2/9/2021

Etomidate

11

• Expensive – Cost per mL more than propofol – Volume is greater, esp. for large dogs – Smaller dogs may be OK – Can be kept over time

Etomidate

• No CV effects – Good for heart patients

• Decrease ICP – Good for head trauma

• No respiratory effects • Wide therapeutic index

– No CV effects so hard to overdose

Etomidate

• Not controlled • Rapidly metabolized

– Can give repeat boluses – However, be careful adrenal suppression

• Must be given IV

2/9/2021

Etomidate

12

• Use – 0.5-1.5 mg/kg – Over 3mg/kg adrenocorticol suppression

• Summary – No CV/resp depression – Rough inductions

– Expensive – Drug of choice for cardiac disease

Sevoflurane

• Originally synthesized 1971 • Used for long time in Japan • Relatively recently used in animals in US • Owned and promoted by Abbott

– Generic is now available

Sevoflurane

• Primary differences from isoflurane – Solubility – MAC – Side-effects – Cost

2/9/2021

Sevoflurane

13

• Solubility – Less soluble equals faster change in plasma

concentration – Theoretical faster induction/recovery – Solubility difference is definite

• Halothane 2.5 • Isoflurane 1.33 • Sevoflurane 0.65

Sevoflurane

• Solubility – Induction/Recovery Time

• Without premed 13 vs. 10 min extubation dogs • With premed 11.3 vs. 10.5 • Induction no significant difference

– Recovery quality • No significant differentce immediate post-op • Difference later?

Sevoflurane

• MAC – Iso 1.3 – Sevo 2.1 – So, change vaporizer 0.25%

• 0.19 x MAC Iso • 0.12 x MAC Sevo

– Titrate to effect easier

2/9/2021

Sevoflurane

14

• Side-effects – Hypothermia as per isoflurane – Increased ICP as per isoflurane – Waste gasses similar effect – Slightly higher metabolism for Sevo

• Less ideal in liver patients

Sevoflurane

• Side-effects – No difference resp dep. – No difference CV dep. – Byproduct of sevo conceivably nephrotoxic

• No clinical evidence

– Essentially no difference from Iso

Sevoflurane

MAC vs. MAP 110 100

Sevo Hal Iso

90 80 70 60

1.0 1.5

MAC 2.0

MA

2/9/2021

15

Sevoflurane

Sevoflurane

• Cost – Expensive to manufacture – Vaporizers maybe included in contract with Abbott – 14x cost of iso – Generic available cheaper but still expensive

• Less noxious

Sevoflurane

• Use – Vaporizer max 8% – Setting 3-4% typical

• Summary – No difference recovery times or postop quality – Maybe difference long-term recovery?

– No difference side-effects • NO SAFER!

– Significantly greater cost

MAC vs CO2

60 50

Sevo Hal Iso

40 30

1.0 1.5

MAC 2.0

PaC

O2

2/9/2021

16

Nocita

• Liposome-encapsulated bupivacaine • Sustained release of local anesthetic • Equal to epidural analgesia for stifle surgery • Injected into peri-wound tissue

• Fairly expensive • Other uses unsure

– Dentals seemed to do a little better day 1-2 postop

Implementation

• Dexmedetomidine – Healthy dogs needing heavy sedation – Use bottle dose or my dose – Don’t be afraid of bradycardia – Profound sedation/analgesia

• Don’t OD induction • Don’t OD inhalant

– Make sure to charge appropriately

Implementation

• Buprenorphine – Easy – Replace current analgesic – May need to increase charge – Educate clients for transmucosal absoprtion

2/9/2021

Implementation

17

• Propofol – Doing a lot of bulldogs, neonates – Titrate to effect – Will need to increase charge relative to ket/val

• Propofol 28 – No more discarding!

– May need to increase pricing but hopefully not

Implementation

• Alfaxalone – Intractable patients, reptiles – Sick patients – Client charge should be appropriate

Implementation

• Etomidate – Very sick patients – Cardiac patients – Small patients not too expensive – Induction rougher – Charge appropriate

2/9/2021

Implementation

18

• Sevoflurane – Picky clients – Edge over other guy – Higher vaporizer setting than iso – Need to adjust charging

Conclusion

• New drugs sometimes good • Sometimes marketing ploy • Newer not always better • Friendly local anesthesiologist can help!

2/9/2021

1

Pain Management Alternatives

Dr. Erik Hofmeister

Outline

• General Principles • NSAIDs • Oral Opioids • Gabapentin

• Amantadine • Physical • Integrative

General Principles

• Alternatives necessary – Refractory acute, severe pain (surgery, trauma) – Patient intolerant to traditional drugs – Hit variety of pathways – synergy – Chronic, burning pain poorly responsive to

traditional drugs – Difficult client situations

2/9/2021

General Principles

– Loss of enjoyment of activities

2

• Chronic pain – Usually outpatient – Long-standing, established pain – Underlying disease not treatable – Strong drugs not available – Pain mild to severe – Client administration consideration

– Treatment success frustrating – Try many different treatments

General Principles

• Individual responses may be due to – Genetic differences in receptors – Difference in metabolism – Different disease states

• Individualized patient care important – Incorporate client needs/values – Discuss goals/objectives – Make sure reality is discussed (similar to seizures)

General Principles

• Human pain experience – Significant psychological/emotional component – Cognitive-behavioral therapy highly effective – Animals don’t have pain hangups/fears – Difficult to relate animal and human pain

• Chronic animal pain – Suffering – Immobility

2/9/2021

NSAIDs

3

• Historically caused significant probs – Esp GI

• Newer drugs dramatically safer • Explosion of products available

– Significant market – Difficult to pick out stellar performers

– Sometimes overly excited promotion (Vioxx)

NSAIDs

• Older-style drugs – Ketoprofen: significant GI hemorrhage, not

recommended (Banfield) – Buffered aspirin (Ascriptin): works fine for some

patients; GI effects limit – Flunixin meglamine (Banamine): not usually used

in dogs/cats; GI, kidney problems – Aspirin: GI effects – In general, not necessary in today’s market

NSAIDs

• Newer drugs – More selective for COX 2 – Cox2 responsible for inflammation – Cox1 responsible for side-effects, esp. GI – More Cox2 selective should be better! – …however, not so simple – NOT safe enough to mix – NEVER mix with steroids

2/9/2021

NSAIDs

4

• Carprofen (Rimadyl) – Large number of studies – Proven safety in variety of situations – Rare liver complications (warrant monitoring?) – Safe in cats (off-label) – As effective as butorphanol for surgical pain – Good for chronic pain – Chewable tablets

– Injectable form available

NSAIDs

• Deracoxib (Deramaxx) – Coxib class even more Cox2 specific – Not recommended for cats – High doses CAN cause GI effects – Difficult dosing small dogs – Rare deaths associated with use

NSAIDs

• Etodolac (EtoGesic) – Similar to carprofen – Not as much evidence – Generally well tolerated – Can have GI effects – Dosing can be difficult

2/9/2021

NSAIDs

5

• Meloxicam (Metacam) – Related to piroxicam – Only one approved in cats – However, can cause renal damage (esp. longer

use) – Good evidence of safety in variety of settings – Easy to dose esp. smaller patients – Injectable form available

NSAIDs

• Tepoxalin (Zubrin) – Inhibits lipoxygenase as well as Cox – Dual inhibitor of arachadonic acid – Licensed for use in dogs and cats – Unknown effects of anesthesia – Dissolvable tablet – GI side-effects most common

NSAIDs

• Individualized response – Some dogs do great with some drugs – Some don’t tolerate side effects – May need to change if no success – Wash-out period recommended (7 days) – Don’t give up!

• First line against chronic pain • Can be very effective

2/9/2021

Oral Opioids

6

• Classic rationale for lack of use – Poorly absorbed – Ileus – Dysphoria – Client diversion – Inappropriate/insufficient metabolism (codeine) – Perceived ineffectiveness

Oral Opioids

• Advantages – Good for mod-severe pain – Easy to administer – Relatively inexpensive

• Disadvantages – Can cause GI upset – Can cause dysphoria (unlikely) – Client diversion

Oral Opioids

• Codeine – Mild opioid – Not as divertible as morphine – Often marketed with NSAID- be careful! – Physical dependence develops – Maybe best reserved for severe/cancer pain – Cats metabolism maybe not same as dog – 1-2 mg/kg PO q6-8h

2/9/2021

– Do not give with psychoactive medications

7

Oral Opioids

• Morphine – Highly effective analgesic – Can cause GI problems regularly (constipation) – Easily diverted – Bioavailability relatively low – Good for severe/cancer pain – Inexpensive – Can be used in cats

– 0.5-2 mg/kg PO q6h

Oral Opioids

• Buprenorphine – Technically transmucosal – Easily administered cats – Dogs TM absorption also OK – put in side of

mouth; large volume – Highly effective, minimal side effects – Not easily diverted – Administer 0.01-0.02 mg/kg PO q8h

Oral Opioids

• Tramadol – Mild opioid effects – Other effects: serotonin, norepinephrine, NMDA – OK for mod-severe pain – Dosing in dogs 2+ mg/kg PO – Dosing interval: q6h – Can be used in cats – GI effects (constipation, vomiting) most common

2/9/2021

Oral Opioids

8

• Use – NSAIDs insufficient – NSAID side-effects too problematic

• Carry own side-effects

• Consider diversion potential • Very good analgesics • Relatively inexpensive

Gabapentin

• GABA analog – Synthesized to be similar to GABA – However, does not act at GABA – Maybe affects synaptic formation

• Anti-seizure original use

Gabapentin

• Neuropathic pain analgesic – Unknown mechanism of action

• Not controlled – However, some psychotropic effects

• Xylitol sweetener in human compoundings – Do not use for dogs

• Fairly expensive, esp. for large dogs

2/9/2021

9

Gabapentin

• In people, a third of patients with some conditions respond

• One study dogs – No significant benefit amputation cases

• Anecdotal evidence beneficial in chronic pain • Maybe useful in some patients

• Adverse effects – Sedation, dizziness, edema (in people)

Gabapentin

• Clinical Use – 2-10 mg/kg PO q12h – Long-term treatment maybe necessary to see

effect – Probably most useful neuropathic pain – Maybe useful other chronic pain – Worth trying if client has patience

Amantadine

• Originally designed as anti-influenza drug • Weak NMDA antagonist

– Dopamine and norepinephrine effects – Decreases central sensitization – However, sensitization has often already occurred

• Equivocal analgesia in people

2/9/2021

10

Amantadine

• Improves client-perceived analgesia in chronic arthritis

• Unknown other disease states • Minimal side effects • Dose 2-5 mg/kg PO q24h x3+ weeks

– Maybe can wean off over time • Not expensive • Useful in refractory cases and when not much

else to do

Physical

• Nearby mechanoreceptors – Cross-react with nociceptors

– Low-level stimuli of nociceptors • Influence signal processing in spinal cord

• Gating of some signals may be occurring – Stimulating other neurons may result in decrease

firing of nociceptors

Physical

• Increased blood flow improves healing • Increased activity improves ROM and

decreases stiffness • Give patient something to ‘do’ • Client-oriented benefits

2/9/2021

• Chiropracty

11

Physical

• Massage – Non-painful inputs

• Physical therapy – Improve ROM and return to function

• No real evidence in animals yet – Certified canine rehabilitation

– Cats may not tolerate well • In people, very important field

Integrative

• Techniques that may work – However, mechanism unknown – Placebo effect – Not generally well accepted – May have role in some clinics and with some

clients

Integrative

• Magnetism • Transcutaneouos electrical nerve stimulation

(TENS) • Ultrasound • “Cold” laser • Acupuncture

2/9/2021

Integrative

12

• Magnetism – Core followers/believers – No scientific evidence in people or animals – Manipulate magnetic fields to achieve effects – Change energy flow in patient – Inexpensive – No side-effects

Integrative

• TENS – Similar mechanism to physical methods – Evidence in people for pain relief for post-op,

arthritis, musculoskeletal – Maybe beneficial neuropathic pain – Devices cost money – No significant adverse effects

Integrative

• Ultrasound – Used in human PT – Heats deeper tissues – Decrease muscle spasm – Increase healing/decrease scarring – No evidence yet – Units can be costly

2/9/2021

• Chiropracty

11

– No significant side-effects

2/9/2021

Integrative

14

Integrative

• Cold laser – Photons from laser cause cellular effects – Increase healing, decrease pain sensation – Useful mostly for superficial pain – Laser light superior to normal light? Better

penetration? – No good evidence – Units variable in expense – No real side-effects

Integrative

• Acupuncture – Stimulation of sites similar to gate-control theory – May increase endorphins – Some patients benefit – Some patients do not – Evidence generally positive – Not expensive – Certifying bodies

– No side effects

Integrative

• Chiropracty – Physical manipulation – Similar to massage/PT – Emphasis on musculoskeletal system – Unknown/unproven mechanism – Effectiveness highly debated – Evidence all over – No real side effects

2/9/2021

– Cost depends on provider

13

• Some patients benefit, some do not – Similar to NSAIDs….

• Some clients benefit • Maybe useful to consider in practice • No side-effects (except cost…) • Maybe all placebo • Can’t hurt, might help

Conclusion

• Pain management complex • Variety of options exist

– Esp. chronic pain – Generally: no single best strategy

• Discussion with clients key – Setting expectations

• Willingness to try variety – Similar to internal medicine cases…

anaesthesia crises

Documents