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KEY CONCEPTS IN ACUTE PAIN MANAGEMENT SURGERY RESIDENTS Feb' 7, 2006

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Discuss key concepts of each modality. Always a COX-inhibitor before opioid ... 'Optimal' analgesia is often difficult to titrate ... – PowerPoint PPT presentation

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Title: KEY CONCEPTS IN ACUTE PAIN MANAGEMENT SURGERY RESIDENTS Feb' 7, 2006


1
KEY CONCEPTS IN ACUTE PAIN MANAGEMENT - SURGERY
RESIDENTS Feb. 7, 2006
  • John Penning MD FRCPC
  • Director Acute Pain Service

2
Objectives
  • General Key Concepts
  • The real cost of acute pain
  • Multi-modal analgesia
  • Discuss key concepts of each modality
  • Always a COX-inhibitor before opioid
  • Tylenol 3 has its limitations
  • Review principles discussed by case presentation
  • Opioid tolerance, conversion from IV to PO
  • When, how to use naloxone
  • Assessing the hypotensive epidural patient

3
Consequences of poorly managed acute
post-operative pain
  • The Patient suffers
  • CVS MI, dysrhythmias
  • Resp atelectasis, pneumonia
  • GI ileus, anastamosis failure
  • Endocrine stress hormones
  • Hypercoagulable state DVT, PE
  • Impaired immunological state
  • Infection, cancer, wound healing
  • Psychological
  • Anxiety, Depression, Fatigue
  • Chronic Post-surgery/trauma Pain

4
Consequences of poorly managed acute
post-operative pain
  • The Hospital
  • Increased costs
  • Poor staff morale
  • Reputation/Standing in the Community, Nationally
  • Accreditation
  • Litigation
  • The Healthcare professional
  • Morale
  • Complaints to College
  • Litigation

5
Benefits of Optimal Acute Post-Operative Pain
Management
  • The Hospital
  • Increased patient satisfaction
  • Increased staff morale
  • Compliance with national guidelines,
    accreditation criteria
  • Cost Savings
  • Earlier ambulation and enteral feeding
  • Decreased complications/ICU expenditures
  • Decreased Length of Stay

6
The New Challenges in Managing Acute Pain after
Surgery and Trauma
  • Patients/Society more aware of their rights to
    have good pain control
  • We are being held accountable
  • Pressure from hospital to minimize length of stay
  • Control pain, limit S/E and complications

7
The New Challenges in Managing Acute Pain after
Surgery and Trauma
  • The Opioid Tolerant Patient
  • The greatest change in practice/attitudes in the
    last 10 years is the now wide spread acceptance
    of the use of opioids for CHRONIC NON-MALIGNANT
    PAIN
  • Renders the usual standard box orders totally
    inadequate in these patients
  • Get an accurate Drug History

8
What is the Best Way to manage acute
post-operative pain?
  • FIRST, DO NO HARM
  • Therefore, the best way is a BALANCE

Effective Analgesic Modalities
Patient Safety
9
KEY POINTS
  • Emphasis is placed on the utilization of a
    multimodal analgesic approach to maximize
    analgesia while minimizing side-effects.
  • Transduction
  • Transmission
  • Modulation
  • Perception
  • There is as of yet no single silver bullet!!

10
Pain Pathways
11
Acute Pain Management Modalities
  • Cyclo-oxygenase inhibitors
  • Non-specific COX inhibitors(classical NSAIDs)
  • Selective COX-2 inhibitors, the coxibs
  • Acetaminophen is probably COX-3
  • Opioids
  • NMDA antagonists
  • Ketamine, dextromethorphan
  • Anti-convulsants
  • Gabapentin, Pregabalin
  • Local anesthetics

12
Tissue Trauma
Cell Membrane Phospholipids
Phospholipase
Arachidonic Acid
COX
Cyclo-oxygenase
Endoperoxides
Toxic Oxygen Radicals
Thromboxane
Prostacyclin
Prostaglandins
13
Case Problem Inadequate Analgesia with IV PCA
after Open Cholecystectomy
  • 45 yr. female c/o severe pain at rest and
    difficulty breathing due to incisional pain- 4
    hrs. post-op
  • IV PCA morphine 1mg bolus, 5 min. lock-out, no
    continuous infusion
  • 150 demands 28 good
  • has stopped using PCA because, it is making me
    sick(N/V) and its not working
  • received 25 mg gravol X 2 one hour ago which
    helped just a little with the N/V, but did make
    her quite groggy
  • Solution!
  • Continuous infusion? Increase bolus dose?

14
Case Problem Inadequate Analgesia with IV PCA
after Open Cholecystectomy
  • Problem Patient unable to attain required
    morphine blood level due to intolerable
    side-effects (N/V, sedation)
  • Solution
  • Administer NSAID
  • Toradol IV/IM, Naprosyn 500 mg PR Q12H and this
    may be changed to 250 mg PO TID with meals once
    eating
  • Control N/V
  • Maxeran/Stemetil, Ondansetron, Decadron
  • May need to consider changing opioid i.e. Demerol

15
Mortality From NSAID-Induced GI Complications vs
Other Diseases in US
Wolfe MM NEJM 1999 340 1888-99
16
Pennings Pessimistic Policy on Pain Pills
  • Pick your Poison Pursuant to Patient Profile
  • COX-inhibitors are potential killers
  • in the long run
  • Opioids are potential killers
  • in the short run

17
Analgesia with Opioids alone
  • The harder we push with single mode analgesia,
    the greater the degree of side-effects

Side-effects
Analgesia
18
Multi-modal Analgesia
  • With the multimodal analgesic approach there is
    additive or even synergistic analgesia, while the
    side-effects profiles are different and of small
    degree.

Side-effects
Analgesia
19
Case Problem Severe Respiratory Depression
after Toradol?
  • Healthy 34 yr. patient c/o severe incisional pain
    in PACU after ovarian cystecomy
  • Received 200 ?g fentanyl with induction and 10 mg
    morphine during case
  • PCA morphine started in PACU, plus nurse
    supplements totaled 26 mg in 90 minutes
  • Still c/o pain, 30 mg Toradol IM given with some
    relief after 15 minutes, so patient sent to ward
  • 60 minutes later found unresponsive, cyanotic, RR
    4/min.

20
Case Problem Severe Respiratory Depression
after Toradol?
  • Pharmacodynamic drug interaction between morphine
    and NSAID
  • morphines respiratory depressant effect opposed
    by the stimulatory effects of pain, busy PACU
    environment
  • NSAID decreases pain, morphines effect
    unappossed
  • Gain control of acute pain with fast onset, short
    acting opioid(fentanyl)
  • Add NSAID adjunct early
  • Monitor closely for sedation and respiratory
    depression after pain is alleviated by any means

21
The problem with the Little Pain Little Gun,
Big Pain Big Gun Approach
  • With opioids analgesic efficacy is limited by
    side-effects
  • Optimal analgesia is often difficult to
    titrate
  • 10 fold variability in opioid doseresponse for
    analgesia
  • A dose of opioid that is inadequate for patient A
    can lead to significant S/E or even death in
    patient B.
  • Many patient factors add to the difficulty
  • Opioid tolerance, anxiety, obstructive sleep
    apnea, sleep deprivation, concomitantly
    administered sedative drugs

22
The rationale for COX-Inhibitors in acute pain
management
  • The problem with the Little Pain Little Gun,
    Big Pain Big Gun Approach
  • Patient Safety!! If the Big Gun is failing due
    to dose limiting sedation/respiratory depression,
    the addition at that time of the Little Gun may
    kill the patient.

23
NSAID and Acetaminophen
  • CONCEPT 1
  • The foundation of all acute pain Rx protocols.
  • First on last off
  • sole agent in mild /moderate pain
  • Analgesic efficacy is limited inherently
  • In contrast, with opioids efficacy is limited by
    S/E
  • adjunctive analgesic for patients requiring
    opioids
  • opioid sparing effect 30-60

24
The rationale for pre-operative administration
  • The benefits of Pre-emptive Analgesia
  • Goal prevent the establishment of peripheral
    and central sensitization (wind-up), conditions
    that lead to an augmented response to pain
    stimuli
  • i.e. prevention of hyper-algesic state
  • Requirements the analgesic must be
    pharmacologically active at the time of surgical
    incision and its activity must be maintained
    peri-operatively. ( gt 1 hr. pre-op for PO/PR
    NSAIDs)

25
The rationale for pre-operative administration
  • Pre-emptive Analgesic effect of Rofecoxib after
    Ambulatory Arthroscopic Knee Surgery. Scott S.
    Reuben et al. Anesth Analg 200294 55-9.
  • Showed that 50 mg of rofecoxib PO one hour before
    surgery is better than 50 mg PO upon completion
    of surgery. VAS at 24 hours
  • Control Rest 3.5
    Movement 4.0
  • Post-incision Rest 2.3 Movement
    3.1
  • Pre-incision Rest 1.8 Movement
    2.4

26
Cyclo-oxygenase inhibitors
Acetaminophen
Naproxen

Celecoxib

Ketorolac
Rofecoxib
27
Cell Membrane Phospholipids
Phospholipase
Arachidonic Acid
COX-2
COX-1
Prostaglandins
Prostaglandins
Acute Pain
Gastric Protection
Inflammation
Platelet Hemostasis
Fever
Renal Function
28
Why a COX-2 inhibitor?
  • Equivalent analgesic efficacy with non-selective
    COX-inhibitors
  • No effects on platelets!
  • Better GI tolerability
  • Less dyspepsia, less N/V

29
Cyclo-oxygenase inhibitors
  • The

  • CAMPAIGN

"COX-2 FOR U"
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COX-2 for U?
  • COX-2 blockers, like Celebrex may not be suitable
    for patients at risk for thrombotic complications
    peri-operatively
  • We need an other campaign slogan?

32
Cyclo-oxygenase inhibitors
  • The

  • CAMPAIGN

"Block the COX"
33
Two hours before surgery associated with post-op
pain
  • Celecoxib 400 mg PO
  • Healthy patients
  • Naproxen 500 mg PO
  • Patients at risk for thrombotic complications
  • Acetaminophen 1000 mg PO
  • Contra-indications to NSAID

34
36 yr. Open Cholecystectomy patient experiencing
difficulty weaning from IV PCA
  • Endometriosis, fibromyalgia and chronic low back
    pain- has been on Tylenol 3 for several years-
    functions well and stable usage of 8-10/day
  • Day 3 post-op Tylenol 3, 2 tabs Q4h started and
    IV PCA D/C
  • Patient c/o severe pain, not able to go home

35
36 yr. Open Cholecystectomy patient experiencing
difficulty weaning from IV PCA
  • A better way?
  • Celecoxib 400 mg PO gt 2 hours pre-op, after
    Naproxen 500 mg PR Q12H to 250 mg PO TID
  • On day 2, when patient is tolerating diet, review
    the 24 hour consumption of IV PCA morphine
  • Multiply the total by 2(for conservative IV to PO
    conversion) and divide by 6 to derive the Q4H PO
    morphine dose
  • 90 mg IV X 2 180 mg, 180 mg/6 30 mg PO Q4H
  • Order the PO morphine straight, plus an
    additional half dose for breakthrough pain, prn
  • Permit 6 hours overlap between IV PCA and PO

36
The Opioids
  • We have to stop trying to put every patient in
    the analgesic dose box

Meperidine 75 mg IM Q4H prn
Tylenol 3 1 2 PO Q4H prn
37
Opioids
  • Concept 2
  • The dose of opioid administered is dependant upon
    multiple factors
  • Pharmacological tolerance to opioids?
  • Route of administration
  • PO, IM/SC, IV bolus, intrathecal
  • Age
  • Weight
  • Severity of pain

38
Opioids
  • CONCEPT 3
  • Pharmacokinetic Pharmacodynamic
  • patient to patient variability results in1000
  • variability in opioid dose requirements
  • (standardized procedure, opioid naĆÆve
    patient)
  • opioid dosage must be individualized
  • therefore, if parenteral therapy indicated, IV
    PCA much better suited to individual patient
    needs than IM/SC

39
Opioids Cancer Pain Monograph (HW,
1984)
  • CONCEPT 4
  • Under utilization of high efficacy PO opioids
  • PO opioid equivalence of 10 mg morphine IM/SC
  • Morphine 20 mg
    meperidine 200 mg
  • Hydromorphone 4 mg codeine 200
    mg
  • oxycodone 10 mg

40
True or False?
  • One opioid is just like any other, in terms of
    analgesic efficacy and side-effects.
  • The is considerable variability between patients
    in response to different opioids
  • Meperidine should be eliminated from the hospital
    formulary

41
Opioids Do they all act the same?
  • Opioids work as analgesics by activating
    endogenous pain modulating systems
  • Opioid receptors
  • Mu, Delta and Kappa
  • Large genetic variability in expression
  • Good choice in one patient may be poor choice in
    another
  • Analgesic efficacy
  • Side-effect profile

42
Opioids Are they all the same?
  • Morphine
  • Hydromorphone (dilaudid)
  • Oxycodone
  • Meperidine (demerol)

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44
Meperidine
Morphine
Atropine
Fentanyl
Bupivacaine
45
Meperidine Pharmacology
  • Opioid agonist Mu and some kappa
  • NMDA antagonist (weak)
  • Local anesthetic action equipotent to lidocaine
  • SSRI (weak)
  • Muscaric blockade atropine-like
  • Central anti-cholinergic effects often causes
    confusion in the elderly

46
Meperidines major problem
  • Normeperidine
  • The ugly metabolite
  • Neuroexcitatory twitches, dilated pupils,
    hallucinations, hyperactive DTR, seizures
  • Non-opioid receptor mediated, no tolerance
  • Half-life is 15 20 hours

N-demethylation
47
Meperidine and MAO Inhibitors
  • Meperidine blocks the neuronal re-uptake of
    serotonin, may result in serotonergic crisis in
    patients being treated with MAO inhibitors
  • Excitatory reaction with delirium, hyper or hypo
    tension, hyperthermia, rigidity, seizures, coma,
    death
  • Supportive management, ? Benzos, dopaminergics?

48
When to use Meperidine?
  • As a third line opioid when other choices have
    failed
  • Especially if patient has Hx of such
  • Less than 600 mg per day
  • Short duration of 2 days or less
  • Avoid in elderly or renal failure patients
  • May be useful in small IV doses to supplement
    other opioids
  • 25 mg IV Q1H prn

49
True or False?
  • Codeine is a weak opioid?
  • Codeine is inherently safer than the more potent
    opioids?

50
CODEINE A drug whose time has come and gone?
N Engl J Med 351 27 Dec. 30, 2004
51
Problems with Codeine
  • 62 yr. male with CLL, presents with bilateral
    pneumonia.
  • Broncho-lavage revealed yeast
  • Anti-biotics Ceftriaxone, clarithromycin,
    voriconazole
  • Codeine 25 mg PO TID for cough

52
Problems with Codeine
  • Day 4 became markedly sedated, pin-point pupils
    and ABG reveals PaCO2 of 80 mmHg. Marked
    improvement with Naloxone.
  • Whats the expected morphine blood level?
  • Answer 1 to 4 mcg/L
  • This patients morphine blood level?
  • 80 mcg/L

53
Codeine Metabolism in Normal Circumstances
  • The major pathways convert codeine to inactive
    metabolites
  • CYP3A4 pathway yields norcodeine
  • Glucuronidation
  • The minor pathway, about 10, yields morphine
  • CYP2D6, essential for analgesic effect
  • 60 mg Codeine PO approx. 4 mg morphine SC
  • Variability! 60 mg PO Codeine yields potentially
    0 to 60 mg parenteral morphine

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Potential Codeine Drug Interactions
  • Major pathway CYP3A4
  • Inducers decrease codeine effect
  • Inhibitors increase codeine effect
  • Minor pathway - CYP2D6
  • Inducers increase codeine effect
  • Inhibitors decrease codeine effect

59
Inhibitors of CYP2D6
  • SSRIs (potent) especially PAXIL
  • Cimetidine, Ranitidine
  • Desipramine
  • Propranolol
  • Quinidine (potent)
  • Viagra
  • Many anti-biotics and chemo

60
Instead of Tylenol 3 ?
  • Acetaminophen 650 mg PO Q4H
  • Morphine 10 20 mg PO Q4H prn
  • OR
  • Dilaudid 2 4 mg PO Q4H prn

61
Why combination analgesics are not a great idea
  • Acetaminophen-Induced Acute Liver Failure
    Results of a USA Multicenter, Prospective Study.
    Hepatology, Vol. 42, No. 6, 2005. Larson et al.
  • 22 centers, 662 cases 98 03.
  • 50 cases due to acetaminophen
  • 50 of acetaminophen cases inadvertent

62
The Limitations of Tylenol 3
  • The problem with combination drugs
  • The codeine dose is limited by the maximum
    allowed dose for acetaminophen
  • 4 grams/day 12 tabs/day
  • 12 X 30 mg 360 mg codeine 60 mg morphine
  • 60 mg PO 15 30 parenteral morphine
  • Equals about 1 mg/hr IV/s.c.
  • Adequate for moderate pain in average patient?
  • Net result is limited efficacy

63
The Limitations of Tylenol 3
  • The problem with combination drugs
  • Acetaminophen therapy may be limited by
    intolerance to codeine
  • Patient sensitive to codeine may only want to
    take 1 T3 or even 1/2. If all they can tolerate
    is 15 mg of codeine Q4H, the patient is not
    receiving the benefit of optimum dose of
    acetaminophen

64
The Limitations of Tylenol 3
  • The constipation problem
  • Codeine may be more constipating than other
    opioids
  • The codeine allergy problem
  • True immunological allergy is extremely rare
  • 99.9 of allergy are sensitivities
  • N/V, excessive sedation, confusion
  • Need to perform adequate drug history, otherwise
    problems may arise when an even more potent
    opioid, such as Percocet is substituted for T3.

65
The Limitations of Tylenol 3
  • 1/ Codeine is a pro-drug
  • 2/ The problem with combination drugs
  • a. The codeine dose is limited by the maximum
    allowed dose for acetaminophen
  • b. Acetaminophen therapy may be limited by
    intolerance to codeine
  • c. Acetaminophen toxicity
  • 3/ The constipation problem
  • 4/ The codeine allergy problem

66
Solution to the T 3 limitations Provided
codeine works in your Patient
  • The oral analgesic ladder

Oxy 5 mg
T3
T3
T3
T3
T3
T
T
T
67
Solution to the T 3 limitations
  • Every 12 hours

Long Acting Opioid
Cox-inh Long Acting
For breakthough pain Regular opioid PO Q4h
prn Acetaminophen 650 mg PO Q4h prn
68
Opioids
STOP
  • Hydromorphine 1 4 mg PO/IM/IV Q4H prn
  • NOT!
  • This represents up to 30 fold range in peak
    effect in any given patient
  • 1 mg PO ---- 4 mg IV bolus
  • homeopathic dose ---- potentially lethal

69
Opioids Rational multi-route orders?
  • Foundation of Acetaminophen/NSAID
  • Morphine 5 - 10 mg PO Q4h prn
  • Morphine 2.5 - 5 mg s.c. Q4h prn
  • Morphine 1-2 mg IV bolus Q1h prn
  • Hydromorphone 1 - 2 mg PO Q4h prn
  • Hydromorphone 0.5 1 mg s.c Q4h prn
  • Hydromorphone 0.25 0.5 mg IV Q1h prn

70
When a fast onset/short duration opioid is
required!
  • Fentanyl 25 - 50 ug IV bolus Q 2 - 3 minutes
  • onset in 30 seconds
  • peak effect in 5 min. (30 min. with morphine)
  • short duration of action due to lipid
    solubility, redistribution half-life is 15
    minutes
  • very potent respiratory depressant, give
    supplemental Oxygen, monitor SaO2
  • be very careful when benzodiazepines are also
    administered ie. Versed
  • Airway management skills/equipment available
  • Naloxone

71
Case Problem32 yr. Male with multiple ribs
  • Patient previously healthy, MVA with no other
    injuries.
  • In Trauma Unit, c/o 9/10 pain. Difficultly
    breathing due to severe splinting.
  • Analgesic orders are
  • Morphine 2 10 mg PO, SC, IV Q4H prn
  • Nurse just gave 5 mg PO one hour ago and now
    wont give anything for 3 hours!
  • What do you do?

72
Case Problem32 yr. Male with multiple ribs
  • Review of PHx reveals no drug use.
  • Patient has received total of 24 mg morphine in
    the 6 hours since admission.

73
Case Problem32 yr. Male with multiple ribs
  • Ketorolac 30 mg IV stat followed by 10 mg IV Q4H.
  • Morphine 10 15 mg s.c. Q4H
  • Morphine 2 - 3 mg IV Q1H prn
  • Ketamine 2.5 5 mg IV Q30 min. prn

74
NMDA Antagonists as analgesics
  • Really anti-hyperalgesics, anti-pronociceptive
  • Central system of facilitatory pain pathways that
    employ excitatory neurotransmitters
  • Aspartate, glutamate
  • Involved with central sensitization, Opioid
    tolerance and Opioid Induced Hyper-algesia
  • NMDA antagonists block the facilitatory pain
    pathways that induce pathological acute pain
  • Hyperalgesia, allodynia

75
Hyperalgesia
Excitatory Mechanisms NMDA Agonists
PAIN
Inhibitory Mechanisms OPIOIDS
Analgesia
76
NMDA Receptor Antagonists -To prevent or reverse
pathological acute pain
  • Ketamine, Dextromethorphan
  • Ketamine is widely known as a dissociative
    general anesthetic - 3 mg/Kg IV bolus
  • Ketamine 2.5 - 5.0 mg IV bolus for analgesia in
    post-op patient -
  • Ketamine as co-analgesic - combined 11 with
    morphine IV PCA. Better analgesia, less S/E
  • Dextromethorphan 30 mg PO Q8H available OTC as
    Benylin DM, 3 mg/ml.

77
Case Problem32 yr. Male with multiple ribs
  • IV PCA with morphine / ?ketamine
  • Ketorolac changed to naproxen when eating. 250
    mg TID
  • Or
  • Celecoxib 200 mg Q12H for 5 days then 100 mg
    daily until no longer needed.

78
Case Problem32 yr. Male with multiple ribs
  • On day three patient is doing well and planning
    for D/C tomorrow.
  • Convert to PO morphine.
  • Daily IV PCA use is 100 mg per day.
  • Equals about 200 mg per day orally.
  • Order about 50 as long acting.
  • 60 mg MS Contin Q12H and 10 20 mg PO Q4H prn.

79
Case Problem32 yr. Male with multiple ribs
  • Weaning instructions
  • As daily breakthough morphine requirements
    decrease, reduce the MS Contin dose by 25
    increments.
  • The COX-inhibitor is the last to be D/C
  • Acetaminophen may be used in addition to NSAIDs
    and Coxibs

80
Opioids
  • Issue
  • With parenteral opioids the patient may
    experience intolerable side effects before
    adequate analgesia is attained

81
Opioids
  • CONCEPT 3
  • Targeted regional
  • administration of opioid
  • results in enhancement of
  • the therapeutic index (ratio
  • of analgesia/side effects)

82
Acute Pain Management ModalitiesWho Gets What
and Why??
  • Intrathecal morphine
  • simple technique
  • potent analgesia for 12 -16 hrs.
  • highly effective for pain in lower abdomen and
    lower limbs
  • risk of delayed onset of respiratory depresson
  • C/S, Vag. Hyst., Rad. Prostatectomy, Arthroplasty

83
Neuraxial Morphine Side-effects Intrathecal
300Āµg Epidural 3 mg
  • Pruritus
  • gt60 of post-partum patients
  • easily treated with nalbuphine
  • increased risk reactivation of oral herpes
    simplex
  • Urinary Retention
  • suggest leave foley in for 12 hours
  • Delayed Respiratory depression
  • Peaks at 4-6 hours after administration
  • Incidence depends on patient population
  • Rare in properly selected patients

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What is an EPIDURAL?
  • Anatomical
  • Location of the catheter, C7 L5
  • Cervical, thoracic and lumbar epidurals
  • Segmental Blockade
  • Drugs
  • Opioids (hydrophillic vs. lipophillic)
  • morphine, hydromorphone, demerol, fentanyl
  • Hydrophillic drugs migrate rostrally and also
    yield greater spinal selectivity

86
What is an EPIDURAL?
  • Drugs
  • Local Anesthetics
  • Lidocaine, bupivacaine, ropivacaine
  • Varying concentrations/drug mass produces
  • Differential Blockade
  • sympathetics gt somatosensory gt motor
  • Adjuncts epinephrine, ketamine
  • Mode of Drug Delivery
  • Intermittent bolus vs. continuous infusions

87
True or False?
  • Epidural analgesia impairs the resolution of
    post-operative ileus i.e. it slows down the gut
    delaying return of normal bowel function.
  • Epidural analgesia necessitates a foley catheter
    until the epidural is removed

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Acute Pain Management ModalitiesWho Gets What
and Why??
  • Why bother with epidural local anesthetics?
  • In major bowel surgery the period of
    post-operative ileus is markedly decreased with
    the use of epidural infusions of local
    anesthetics and by the avoidance of high doses of
    opioids
  • promotes vascular graft patency in the early
    post-operative period
  • superior analgesia with fewer side-effects
  • improved outcome and decreased health-care costs
    in high risk patients having major surgery

90
Case Presentation Somnolence and hypoxemia
while on epidural infusion of hydromorphone/bupiva
caine
  • 65 yr. Female with Ca pancreas had partial
    Whipples. Epidural at T8/9, standard
    dilaudid/bup
  • PMHx Angioplasty 9 yr. ago, MI, CHF in past
  • Moderate COPD, NIDDM
  • Dilaudid 4 mg PO Q4H for the last month
  • Early Post-op Required double strength but did
    well
  • Day 4 became increasingly lethargic, somnolent
    and not able to maintain SaO2 gt 90 despite
    supplemental O2.
  • Is Narcan Indicated? Urgently?

91
Case Presentation Somnolence and hypoxemia
while on epidural infusion of hydromorphone/bupiva
caine
  • Further patient evaluation
  • Patient arousable, RR 8-16, pupils slightly
    constricted, BP 130/70, pulse 90 and reg.
  • Chest A/E fair bil. And some mild basilar creps
  • ABG pH 7.46 pCO2 50 pO2 55 BiCarb 36 FiO2 gt
    .50
  • Chest X-ray Extensive bilateral, diffuse,
    interstitial infiltrate consistent with ARDS
  • Naloxone would probably have had a serious
    adverse effect on this patient. Hypoxemia
    despite supplemental O2 in a breathing patient.
    Look beyond the Opioids!

92
Case Presentation Somnolence and hypoxemia
while on epidural infusion of hydromorphone/bupiva
caine
  • Management of suspected opioid induced
    respiratory depression
  • Support A/W
  • Simulate breathing
  • Supply supplemental oxygen
  • Assess SaO2, BP, Pulse
  • Naloxone titration, IF INDICATED
  • 0.04 mg Q5 min. X 3 as needed
  • Hypoxemia is a medical emergency
  • Hypercarbia is NOT

93
Epidural Pit-falls for the Surgeon
  • Epidural hematoma
  • gt 50 reported cases in USA in patients treated
    with LMWH
  • Epidural insertion and removal of the catheter
  • Risk factors Elderly, low body weight, twice
    daily dosing, anti-coagulation vs. prophylactic
    dose range
  • The decision to fully anti-coagulate a patient
    with an epidural in-situ should be made in
    consultation with anesthesia and thrombosis
    medicine

94
Epidural Pit-falls for the Surgeon
  • Masked-Mischief
  • The potential high efficacy of the modality could
    block pain related to complications
  • Peritonitis anastomosis dehiscence
  • Wound infection, wound hematoma
  • Limb ischemia, compartment syndrome
  • Delay in appropriate therapy, diagnosis
  • Neurological problems inappropriately attributed
    to the epidural i.e. anterior spinal artery
    syndrome
  • Hypovolemia

95
The Hypotensive Patient with an Epidural
  • 64 yr. female, 48 kg, with no Hx of CVS problems,
    had an esophagectomy for cancer with combined
    GA/epidural anesthesia.
  • Later that evening you are called because the
    patients BP is 85/50.
  • Epidural at T5/6 and running hydromorphone 10
    Āµg/ml in 0.01 bupivacaine at 8 ml/hr

96
The Hypotensive Patient with an Epidural
  • Possibilities?
  • Normal for this patient
  • all is well and confirmed by Hx and absence of
    postural changes in BP or HR
  • vascular patients may have marked discrepancy
    between arms establish baseline pre-op
  • Surgical complications
  • Medical complications
  • Side-effect of Epidural induced sympathetic block
  • decreased venous return and decreased SVR
  • Combination of any 4 above

97
Is the Epidural causing the hypotension?
  • What drugs have been administered epidurally?
  • Pure opioids morphine, hydromorphone, fentanyl
  • sympathetics not blocked directly so look for
    another cause
  • Demerol
  • mild direct sympatholytic effect and some
    systemic effects in large doses. Rarely cause of
    significant Hypotension. Be careful to R/O other
    causes.
  • Local Anesthetics /- opioids
  • In a euvolemic patient with normal CVS function
    hypotension is unlikely if lt 8 sensory dermatomes
    blocked

98
Is the Epidural Local Anesthetic causing the
hypotension?
  • Intrathecal catheter migration
  • Inadvertent overdose
  • Un-masking of problem with the patient.
  • Sensitive patient

99
Is the Epidural Local Anesthetic causing the
hypotension?
  • Management
  • ABCs
  • supplemental O2, fluid bolus, elevate legs
  • ephedrine 5 mg or phenylephrine 50 Āµg IV bolus
  • Hold the epidural infusion
  • Quantify the extent of block
  • motor block? Thoracic epidural?, thats a
    problem!
  • Sensory block (cold, sharp)
  • In a euvolemic patient with normal CVS function
    hypotension is unlikely if lt 8 sensory dermatomes
    blocked

100
Management of Hypotension Contd
  • High thoracic epidural blockade may block the
    compensatory tachycardia response to hypovolemia.
  • Cardio-accelerator sympathetic nerve fibres arise
    from T1 - T4
  • sympathetic block may extend several dermatomes
    above the sensory blockade
  • Correct the underlying cause
  • Remove bupicacaine and change to epidural
    hydromorphone if patient remains hemodynamically
    unstable

101
ACUTE PAIN MANAGEMENT SCIENTIFIC EVIDENCE 2nd
Edition June 05 Australian and New Zealand
College of Anaesthetists And Faculty of Pain
Medicine.
http//www.anzca.edu.au/publications/acutepain.pdf
The above web site has the entire document and is
freely Available to download.
102
Conclusion Key Concepts
  • The foundation of all acute pain Rx protocols is
    NSAIDS and acetaminophen.
  • Codeine is a pro-drug. Problems may occur with
    under or over conversion to morphine
  • Under utilization of high efficacy PO opioids
  • Pharmacokinetic Pharmacodynamic variability
  • Order opioid dosages rationally, especially with
    patient Hx and route of administration in mind
  • Naloxone can be a dangerous drug, careful
    titration is almost always possible

103
Opioid Conversions Parenteral to Oraland
Equivalents (approx.)
  • Morphine 10 mg Morphine 20 mg
  • Hydromorphone 2 mg Hydro. 4 mg
  • Meperidine 75 mg Meperidine 200 mg
  • Codeine 120 mg Codeine 200 mg
  • Oxycodone (n/a) Oxycodone 10 mg

104
Opioid Conversions Oral to Parenteraland
Equivalents (approx.)
  • Morphine 40 mg Morphine 10 mg
  • Hydromorphone 8 mg Hydro. 2 mg
  • Meperidine 300 mg Meperid.. 75 mg
  • Codeine 300 mg Codeine 120 mg
  • Oxycodone 15 mg Oxycodone (n/a)
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