Department of Anesthesiology

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Practical Approaches to Peri-Operative Pain
Management
Department of Anesthesiology
David P. Tarantino, MD, MBA
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Case Presentation

• You are caring for a 75 year old female who is
  s/p laparoscopic right hemicolectomy. She is
  receiving morphine via a PCA set at 0/2/6.
• She is continuing to complain of terrible pain.

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Questions to Answer

• Why is this patient still complaining of pain?
• How do I evaluate the pain?
• How do I get the patient comfortable?
• What pain medicine(s) should I give?
• How should I order the pain medicine?

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Why is this Patient Still Complaining of Pain?
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Pain Well Thinking

• The Bigger the Surgery You Experience.
• The More It Should Hurt..
• And the Greater Amount of Pain Medicine You
  Should Receive

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Pain Well Thinking

• Therefore, a Small Surgery Requires a Small
  Amount of Pain Medicine.
• A Bigger Surgery Requires More.
• And a Really Big Surgery Deserves the Most Pain
  Medicine

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Whats A Really Big Surgery?
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A Really Big Surgery is any one that happens to
ME!

• Just because something works for most patients
  doesnt mean it is going to work for all patients
• You must individualize therapy
• Protocols are a GUIDELINE only!

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Basic Principle I Talk to the Patient

• Is the patient a Pharmacologic Virgin?
• Get a pain medication history
• What medications does he/she take?

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Basic Principle I Talk to the Patient

• Get a Pain History
• Did he/she have pain prior to this episode?
• What is the pain like now?
• Where does it hurt?
• When did it start to hurt?
• How much does it hurt?
• What makes it better or worse?
• How does it hurt?

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Pain Definitions

• Allodynia Pain from a stimulus which normally
  does not produce pain
• Hyperalgesia Increased response from a stimulus
  that is normally painful
• Both are indicative of neuropathic pain

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Specifics of the Pain Examination

• Are there musculoskeletal or neurologic deficits
  associated with the pain?
• Is allodynia or hyperalgesia present?

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Basic Principle II

• Must obtain pain history and perform a directed
  physical examination

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Front Loading

• It takes five half lives to achieve steady state
  levels in the plasma
• For most opioids that we use the half-life is
  three hours (15 hours to steady state)

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Front Loading

• Lack of appropriate front loading is the most
  common cause for analgesic failure

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How Do I Front Load?

• Step 1 Obtain a pain score
• Step 2 Give IV Analgesic
• Step 3 Wait 5-10 minutes
• Step 4 Obtain a Pain Score
• Step 5 If Ever I Believe My Work is Done, then
  Ill Start Back at One.

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Intravenous Opioid Therapy

• Principle 1 There is little to no reason to
  use IM or SQ therapy to treat acute pain.
• Principle 2 The most common opioids have a
  half-life of three hours
• Principle 3 You must front load the patient
• Principle 4 If you can multiply or divide by
  10, you can easily use these agents

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Intravenous Opioid Therapy

• The Rule of Ten
• 100 mg of Demerol 10 mg of Morphine 1 mg of
  Dilaudid 100 ug of Fentanyl

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Intravenous Opioid Therapy

• A Caution about the use of Demerol
• The active metabolite of Demerol is normeperidine
  which can produce CNS Toxicity
• Half-life of normeperidine is 8-24 hrs
• Use should be very limited, if at all!
• Keep the dose less than 1000mg/day
• Avoid in Elderly and Renal Failure

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Intravenous Opioid Therapy

• A Caution about the use of Morphine
• Morphine is metabolized to M6G and M3G
• M6G can accumulate in patients with renal
  insufficiency
• M6G is 100 times more potent than morphine in the
  CNS

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Patient-Controlled Analgesia

• Three Components
• Bolus Dose How much can the patient receive?
• Basal Rate Background continuous infusion
• Lockout Period Period between doses (6-10
  minutes)

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PCA Problems

• PCA Overdose
• Use of Other agents with PCA
• Bolus dosing must be patient-controlled
• Some patients are not Rocket Scientists

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Stopping a PCA

• Give the patient at least two doses of oral
  opioid prior to D/C of PCA
• Allows the patient to maintain analgesia while
  waiting to achieve steady state plasma levels
  with the oral medication

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How Should I Order the Pain Medicine?
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Problem with Early PRN Dosing

• Prevents achieving and maintaining steady-state
  plasma levels

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Basic Principle III

• Avoid PRN Dosing for the First 24-48 hours
• Give Medications on a Round-the-Clock basis
  according to half-life

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Oral Analgesic Therapy
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Oral Analgesics which can be Problematic

• Codeine
• Must be metabolized to be effective
• 10 of Caucasians lack the enzyme
• High incidence of nausea and vomiting, especially
  in elderly
• Darvon (propoxyphene)
• Active metabolite norpropoxyphene
• CNS Toxicity seizures
• Half life 23-36 hours

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Single Agent Therapy

• Given the availability of single agent opioids,
  there is no reason to give combination therapy
  agents
• Acetaminophen adds little analgesic potency,
  while severely limiting dosage limits and
  intervals
• No reason to give Percocet when you can give
  oxycodone alone.

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Non-steroidal Anti-inflammatory Drugs
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The Role of Cyclo-oxygenase (COX)
Arachidonic acid
Cyclo-oxygenase activity of COX
PGG2
Peroxidase activity of COX
PGH2
PGD2
PGI2
PGF2?
PGE2
TXA2
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Prostanoids and Their Physiologic Activities

• Activities/Properties
• Produced in many organs, (eg, kidney, intestinal
  tract)
• GI mucosal protection/repair
• Vasodilates
• Diuresis and natriuresis
• Inhibits inflammatory/ allergic cells
• ? platelet activation
• ? intravascular platelet aggregation
• ? smooth muscle contraction in arteries and
  bronchi
• ? platelet aggregation
• Vasodilates
• ? renin release in kidney

Prostanoid PGE2
Thromboxane A2
Prostacyclin (PGI2)
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Two Forms of Cyclooxygenase (COX)
COX-1
COX-2

• Constitutive
• Mediate homeostaticfunctions
• Especially important in
• Gastric mucosa
• Kidney
• Platelets
• Vascular endothelium

• Inducible (in most tissues)
• Mediate inflammation, pain, and fever
• Induced mainly at sites of inflammation by
  cytokines

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Special Issues
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Pre-Emptive Analgesia

• Agents Shown to be of Pre-Emptive Benefit
• Ketamine 0.25-1 mg/kg
• Cox-2 Inhibitors
• Neurontin 300 mg
• Local Anesthetics

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How can Four Different Classes of Drugs All
Provide the Benefits of Pre-Emptive Analgesia
and why dont they work as well after Surgery?
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Brain
Inflammatory Mediators
Neuropathic Pain
Nociceptive Pain
Tissue Injury
Local Anesthetics
Nerve Injury
TCAs Anti-convulsants
A delta C fibers
Peripheral Nociceptors
Depolarization
PGE2
Cox-2 Inhibitors
PKC
Mg
I, II Inhbitory interneurons
V (WDR neurons)
NMDA Receptor
Glutamate
Phosphorylation
Ca
Mg
Gabapentin Pregabalin
Ketamine Dextromethorphan Methadone
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Pre-Emptive Analgesia

• Works by preventing acute changes in the
  responsiveness of dorsal horn neurons to noxious
  stimuli
• Must be done before the noxious stimulation of
  surgical incisionoccurs

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Substance Abuse
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Defining the Problem

• General Population 10 have a substance abuse
  history
• U.S. Trauma Centers 40 incidence
• Baltimore Nations Highest Heroin Use
• Highest STDs
• Third most violent
• Third highest HIV

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Defining the Problem

• Little to No Formal Training in addiction during
  medical or nursing school
• Little to No Understanding of Addiction Medicine
• Result Patients who are mislabeled and
  under-treated

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Understanding the Terminology

• AddictionCompulsive use of a substance
  resulting in physical, psychological or social
  harm with continued use despite harm from that
  drug (JAMA 1988259555-557)
• Addiction is inappropriate drug-seeking behavior

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Understanding the Terminology

• Pseudoaddictionappropriate drug-seeking
  behavior (Pain 198936363-366)
• Pseudoaddiction refers to patients who present
  like addicts not because they are addicted, but
  because they seek pain relief
• Incidence of pseudoaddiction is unknown

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Understanding the Terminology

• Dependence physiologic and pharmacologic effect
  that manifests itself as withdrawal
• Tolerance diminished effect with continued use
  of the same amount of substance
• Neither dependence nor tolerance are indicative
  of addiction

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Understanding the Terminology

• Drug-seeking Behavior may be appropriate if its
  purpose is to relieve pain
• Therefore, achieving adequate pain control is
  essential in determining appropriate behavior

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Opioid Agents to Avoid and to Use
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Agents to Avoid

• Agonist-antagonist agents
• May precipitate withdrawal symptoms

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Agents to Avoid

• Avoid short-acting agents
• Example 5 mg of oxycodone 5 mg of IV Morphine
• 10 mg of oxycodone q4hr 60 mg of IV morphine
• Average Substance User at STC uses
• 150 200 mg IV morphine/day

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Agents to Use

• IV Morphine or Hydromorphone (Dilaudid)
• Oral Long-acting Opioids
• Sustained -release Morphine or Oxycodone
• Methadone
• NSAIDS
• Regional Analgesia

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Equi-Analgesic Dosing

• Example 1
• The patient takes 60 mg of MS Contin 3 times per
  day
• 1 mg MS Contin 1 mg IV morphine
• 60 mg MS Contin 60 mg IV morphine
• 180 mg of IV morphine per day

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Equi-Analgesic Dosing

• Example 2
• The patient takes 40 mg of Oxycontin twice per
  day
• 2 mg Oxycontin 1 mg IV morphine
• 40 mg MS Contin 20 mg IV morphine
• 40 mg of IV morphine per day

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Equi-Analgesic Dosing

• Example 3
• The patient takes 80 mg of methadone per day
• 0.5 mg methadone 1 mg IV morphine
• 80 mg methadone 40 mg IV morphine
• 40 mg of IV morphine per day

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Equi-Analgesic Dosing

• Example 4
• The patient uses 4 dime bags of heroin per day
• 1 dime bag of heroin 1 mg IV morphine
• 4 dime bags 40 mg IV morphine

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Equi-Analgesic Dosing

• Example 5 Were you paying attention?
• A pedestrian struck by a car is in a methadone
  program and gets 60 mg per day. After he visits
  the clinic, he buys and snorts 5 dime bags of
  heroin. Because hes in pain, a bystander gives
  him 3 of her Percocets. What is this patients
  current morphine equivalent?
• 60 mg methadone 30 mg IV morphine
• 5 dime bags of heroin 50 mg IV morphine
• 3 Percocets(15 mg oxycodone) 15 mg IV morphine
• Total 95 mg of IV morphine

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Sending the Patient Home

• Is the patient going to Methadone maintenance or
  detoxification program?

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Problems Sending the Patient Home

• May need to wean methadone dose prior to
  discharge
• May need to use combination long-acting agents
• Methadone for addiction
• MS Contin for pain

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Weaning Long-Acting Agents

• Do not attempt to wean until the acute process
  has subsided!
• Pain increases when you go home
• Wean by 10-20 of the total dose every 3 days
• Faster if you add clonidine
• If t.i.d. dosing, wean the afternoon dose first,
  then the morning dose, then the night dose
• Done properly, weaning is a slow process
• It will take weeks to months to properly wean a
  patient from high doses of opioids

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The Alcohol Dependent Patient

• Withdrawal symptoms begin within 6-48 hours and
  peaks at 24-36 hours
• Reverse inhibition from ETOH
• Increased stress hormones, CNS excitation
• May mimic signs of injury (changes in HR or BP)
• Treatment benzodiazepines (symptom triggered vs.
  fixed dose)
• 10 develop seizures
• 5 experience delirium tremens

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The Alcohol Dependent Trauma Patient

• 100 of alcohol dependent injured trauma patients
  have pain!
• Must treat the pain!
• If the patient becomes sedated, it is most likely
  the result of the benzodiazepines
• Therefore reduce the benzodiazepines and not
  the opioids

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Managing the Patient in Recovery
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Managing the Patient in Recovery

• Must treat the pain
• Use regional techniques whenever possible
• PCA works very well allows patient to maintain a
  sense of control
• Input from drug/alcohol counselor (if available)
• Continued commitment to twelve step program

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Regional Analgesia
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Epidural Analgesia
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Epidural Anatomy
Epidural Space
Ligamentum Flavum
Epidural Space
Epidural Needle
Dura
Epidural Veins
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Epidural Opioids Mechanism of Action

• Opioid Receptors in the Dorsal Horn of the Spinal
  Cord
• Systemic Absorption (Lipophilic Agents)

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Combined Opioid/Local Anesthetic Epidural
Analgesia

• Two Sites of Action
• Use Less of Each Agent Fewer Adverse Effects
• May Prevent Adverse Effects

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Patient-Controlled Epidural Analgesia PCEA

• Usual Combination 0.125 bupivacaine or
  ropivacaine and an opioid
• Most of analgesia from basal infusion
• Bolus dose is for breakthrough pain

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Benefits of Combined Epidural Analgesia

• Better pain control
• Earlier ambulation
• Improved Pulmonary Mechanics
• Decreased incidence of DVT
• Faster return of bowel function

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Epidurals and Lovenox

• Current Guidelines
• If on Lovenox, hold for 12 hrs
• After epidural catheter removal, you may start
  Lovenox 2 hrs later
• You should not use Lovenox if the patient has an
  indwelling epidural catheter
• bid dosing
• ? single dosing

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Ultrasound Guided Regional Analgesic Techniques
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Continuous Nerve Block Delivery Systems
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Conclusions

• Treat aggressively/Individualize therapy
• Front Load!
• Give medications on a timed schedule and not
  PRN
• Dose based on the half -life
• Utilize pre-emptive analgesia
• Utilize regional analgesic techniques

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Thank You
Questions?