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Acute Perioperative Pain

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Title: Acute Perioperative Pain


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Acute Perioperative Pain
3
Fundamental Considerations
  • Millions of patients worldwide undergo surgery.
  • Although developing more effective techniques
    for postoperative analgesia, many patients
    experience pain.
  • The concept of perioperative pain management
    by anesthesiologists is now established in North
    America and in many other parts of the world.

4
PERIOPERATIVE PHYSICIAN
  • A physician anesthetist as a consultant and
    therapist throughout an institution as well as a
    highly expert in the operating room.

5
Pain
  • An unpleasant sensory and emotional experience
    associated with actual or potential tissue damage.

6
Pain Pathways
  • Tissue damagegtgtgtAlgesic substanses
    releasegtgtgtNoxious stimuligtgtgtA delta and C
    fibersgtgtgtto theNeuraxisgtgtgtMany toAnt.andAnterolat.
    HornsgtgtgtSegmenal reflex responses , and others
    via the Spinothalamic and Spinoreticular
    tractsgtgtgtSuprasegmental and cortical responses.

7
  • Segmental reflex responses
  • Increased skeletal muscle tone , Increased oxygen
    consumption , Lactic acid production
  • Suprasegmental
  • reflex responses
  • Increased Sympathetic tone , Hypothalamic
    stimulation.

8
Adverse effects of perioperative pain
9
Respiratory effects
  • Surgery of upper abdomen or thorax
  • Reduced V.C. ,Vt ,R.V. ,F.R.C. ,F.E.V.1 .
    Increased abdominal muscle tone Decreased
    diafragmatic function , Reduced pulmonary
    function , Inability to breath deeply or cough ,
  • And in some cases Hypoxemia Hypercarbia ,
    Retention of secretions , Atelectasis and
    Pneumonia .
  • Distended bowel because of ileus and tight
    binders or dressings may further impair
    ventilation

10
Cardiovascular effects
  • Paingtgtgt Increased SNS TONE gtgtgt
  • Tachycardia , increased SV ,Cardiac work and
    Myocardial O2consumptiongtgtgt Myocardial Ischemia
    and infarct.
  • Fear of aggravating Pain gtgtgt Reduced physical
    activity , Venous stasis gtgtgt Risk of DVT .

11
Gastrointestinal and Urinary effects
  • Ileus , Nausea and Vomiting following Surgery.
  • Pain gtgtgt Hypomotility of the Urethra and Bladder.
  • In the case of Ileus , may prolong hospital stay.
  • Postoperative Epidural anesthesia gtgtgt Speed the
    return of bowel function.

12
Psychologic responses
  • Pain gtgtgtFear and Anxiety.
  • When prolonged gtgtgtAnger and adversial
    relationship with Doctors and Nurses .
  • In some cases , Increased pain reporting .

13
Factors that modify perioperative pain
  • 1- Site ,nature and duration of surgery.
  • 2- Type and extent of incision.
  • 3- Physiologic and psychologic makeup of the
    patient.
  • 4- Pre operative preparation of the patient.
  • 5- Presence of complications of surgery.
  • 6- Anesthetic management.
  • 7- Quality of perioperative care.
  • 8- Preoperative treatment of painful stimuli .

14
Preemptive Analgesia
  • Antinociceptive treatment of that prevents the
    establishment of altered central prossesing,
    which amplifies postop. Pain.
  • Windupfunctional changes in the dorsal horn
    because of pain .
  • This type of therapy ,in addition to reducing
    acute pain ,attenuates chronic postop. Pain.

15
Treatment methods
  • 1-Systemic opiods.
  • 2-Patient-controlled analgesia.
  • 3-Regional anesthetic techniques .
  • . a Intraspinal analgesia.
  • b Patient-controlled epidural analgesia.
  • c Combined spinal-epidural technique.
  • 4-intraarticular analgesia.
  • 5-Nonopioid analgesics.
  • 6-Cryoanalgesia.
  • 7-T.E.N.S.
  • 8-Psychologic and other methods.

16
Systemic Opioids
  • Analgesic effects of opioids via receptors in
    the CNS.
  • Roots of administeration I.M. ,I.V. ,Transdermal
    ,Oral ,Topical ,I.V. regional ,Perineural ,etc.
  • I.M. root is the most treatment choice after
    surgery.
  • The As Needed part of the order is often
    interpreted to mean As little as possible .
  • No relation exists between Gender and opioid
    requirement.

17
Patient-Controlled Analgesia
  • PCA was originally developed to minimize the
    effects of pharmacokinetic and
  • Pharmacodynamic variability among patients.
  • A negative feedback loop existsexperiencing
    paingtgtgtMedication demandedgtgtgtReducing pain gtgtgtNo
    further demand .
  • If Nurses, Relatives,or Parents assume
    responsibility for drug administration,or if
    using this device by the patient is for reasons
    other than pain relief ,this loop fails.

18
PCA devices
  • Consists of a microprocessor-controlled pump
    triggered by depressing a button .
  • When pump is triggered ,a preset amount of drug
    is delivered into the patients I.V. line.
  • Lockout interval A specific period setted in the
    pump to prevent administration of an additional
    bolus.

19
  • Cases of respiratory depression during PCA use
    have been reported.
  • Causes advanced age, hypovolemia, large doses,
    use of background continuous-infusion mode.
  • No difference in respiratory mechanics between
    PCA and IM opioids (FEV1,FRC,PFR)is seen.

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Continuous background infusion
  • Advantages
  • 1-more constant serum levels.
  • 2-imrpoved analgesia especially during sleep.
  • 3-modulation of the final opioid dose by patients.

24
  • Disadvantages
  • 1-difficulty predicting the optimal infusion rate
    and thus the possibility of overdose .
  • 2-loss of safety in sleeping patient.
  • 3-more human errors.

25
  • Recommendations for use background
    continuous-infusion mode
  • 1-avoid routine use.
  • 2-add this mode for specific indications e.g
    pain during sleeping hours.
  • 3-base the rate of infusion on 30-50 of demand
    mode.
  • 4-decide if this mode is needed only at night or
    around the clock.
  • 5-provide in-service education to ward nurses.

26
PCA via subcutaneous route
  • for conditions like
  • difficult I.V. access, no option for enteric
    analgesia,
  • Choice of opioids is the same.
  • The concentration of the opioid solutions should
    be increased 5-fold to reduce their volume.
  • The incremental doses and lockout intervals are
    the same.

27
Side effects of PCA
  • Nausea ,Vomiting ,Itching.
  • Treated by changing opioid or using drugs that
    provide symptomatic relief.
  • A pre printed set of standard orders can
    facilitate a uniform standard of care.

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Regional Anesthetic Techniques
  • Advantages
  • Positive respiratory,cardiovascular and
    neuroendocrine effects reduced thromboembolic
    complications and blood loss and reduced
    convalescence

30
  • Interscalene brachial plexus blocks analgesia
    for 12-24 hrs.
  • Sciatic and Femoral n. blocks similar results.
  • Intercostal n. blocks 6-12 hrs. analgesia.
  • Administration of long acting L.A.s from a
    catheter into pleural cavity unilat. Analgesia
    with little or no sensory block.
  • L.A. infusion into Axillary sheath, Femoral
    sheath, and the vicinity of the Sciatic
    n.analgesia and particularly useful to
    facilitate perfusion after extensive
    revascularization or reimplantation surgery,
    maintain a normal ROM after joint surgery, etc.

Interscalene
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L.A. boluses or infusions
  • Advantages over parenteral opioids
  • Early ambulation, improve bowel function, higher
    arterial O2 tension, fewer pulmonary
    complications.
  • For optimal results, the catheter tip should be
    near the segments innervating the insicision.

32
Intraspinal analgesia
  • With
  • Opioids
  • Opioid-L.A. mixture
  • Ketamine
  • Clonidine
  • Neostigmine

33
Opioids
  • Initial reports in 1979.
  • Single injection of intrathecal Morphin provides
    about 24 hrs. analgesia.
  • Epidural root uses more, because
  • Popularity of technique during surgery, ability
    to leave catheter in place, familiarity with
    technique, no risk of PDPH.

34
  • In one study patients receiving epidural morphine
    reported superior analgesia, ambulated sooner,
    had fewer pulmonary complications, had earlier
    return to bowel function, and discharged from
    hospital earlier than patients receiving I.M.
    morphine.

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  • Elderly patients require remarkably small doses
    of epidural morphine.
  • Effective 24-hr. morphine dose
  • 18 age(0.15) .
  • Fentanyl is useful when rapid onset of epidural
    analgesia is important.
  • Epidural meperidine is widely used in some parts
    of the world and as with other opioids,
    respiratory depression can occure.

38
  • Agonist-antagonist opioids (e.g. buprenorphine)
    are popular in some places.
  • This family of drugs offers no significant
    benefits over pure opioid agonists.

39
  • To prevent serious injury or death there is no
    substitute for a high level of vigilancegtgtgt
    checking the rate and depth of respiration and
    general status and level of consciousness at
    frequent intervals by a nurse and respiratory
    monitors with alarms.
  • A preprinted set of orders can facilitate a high
    standard of care .

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  • Delegation of all responsibility for pain control
    to one group of physicians minimizes errors.

42
Respiratory depression
  • early
  • In the first two hrs.
  • Is the result of vascular uptake and
    redistribution.
  • Delayed
  • Between 6 and 12 hrs.
  • Consequent of rostral spread of opioid in CSF to
    respiratory center in the floor of 4th. Ventricle.

43
  • It is not known that severe resp. depression is
    greater after intraspinal opioid .
  • The risk of delayed resp. depression appears to
    be greatest early in the course of therapy and
    there is no reported cases occurring later than
    24 hrs.
  • Respiratory rate is not an adequate indicator of
    ventilatory status.

44
  • Healthy volunteers breathing CO2 mixtures will
    lose consciousness at press. levels of about
    80mmHg.
  • Any deterioration in level of consciousness
    should be assumed to resp. depression until
    disproved by ABG analysis.
  • Immediate treatment support of ventilation
    and/or Naloxone in titrated doses(0.1 mg.)

45
  • Pruritus is a common side effect and is seen more
    in obstetrics patients.
  • Face is a common site of itching.
  • Although it is not due to histamine release,
    antihistamines provide symptom relief.
  • Nalbuphine is also of value.
  • Naloxone is consistently effective (repeated
    doses or infusion).

46
  • Urinary retention is higher in volunteers than in
    patients and in men than in women.
  • Naloxone prevents or reverses it but may require
    doses that antagonizes analgesia.
  • Most patients are able to void spontaneously when
    the catheters are removed.

47
  • Nausea and vomiting due to rostral spread of
    opioid in CSF to the vomiting center and the CTZ
    .
  • Treatment
  • first lineantiemetics (may produce unwanted
    sedation and resp. depression ) , Scopolamine
    patches.
  • Second line I.V.droperidol, Ondansetrone.

48
  • Sedation produced by intraspinal opioids may be
    the result of spread of the drug in CSF to
    receptors in the thalamus, limbic system or
    cortex and hypercarbia can augment it.
  • Epidural buprenorphine 0.15 mg. produces
    prolonged depression of the CO2 response that
    lasts 8-12 hrs.

49
Opioid-L.A. anesthetic mixtures
  • The rational using lower doses of each drug,
    preserving effecting analgesia, reducing side
    effects, and some degree of blunting stress
    response.
  • Opioid in the mixture inhibiting the release of
    substance P in the dorsal horn.
  • L.A. in the mixture blocking transmission of
    impulses at the level of the nerve axonal
    membrane.

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  • Bupivacaine is the most widely used L.A. .

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  • It is possible that dilute Ropivacaine infusions
    will provide analgesia equivalent to that
    provided by Bupivacaine with less impact on motor
    function.
  • The most common opioid used in combination with,
    are Fentanyl and Morphine.
  • Epidural opioids do not appear to mask
    complications (e.g. compartment synd.) but in
    combination with L.A.s it is not known.

53
Ketamine
  • Produces analgesia via interaction with
    cholinergic, adrenergic, and serotonergic
    systems.
  • Side effects sedation, blurred vision,
    tachycardia, hypertension, and hallucinations.
  • In some studies on baboons neurotoxic changes.
  • The routine use of intrathecal ketamine in humans
    is not recommended.

54
Clonidine
  • If administered by the oral route can augment
    spinally mediated opioid analgesia.
  • Epidural or intrathecal clonidine can provide
    effective analgesia alone.
  • Intrathecal clonidine does not provide surgical
    anesthesia.

55
Neostigmine
  • Unlike with L.A.s unwanted axonal blockade does
    not occure, and unlike alpha-2 agonists is not a
    direct agonist stimulating all receptors of a
    certain type.
  • Intrathecal neostigmine gtgtgtinhibiting breakdown
    of actylcholinegtgtgtanalgesia.

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  • 50 micro gr.gtgtgtno effect.
  • 150 micro gr.gtgtgtmild nausea.
  • 500-750 micro gr.gtgtgtleg weakness, decreased DTR,
    and sedation.
  • 750 micro gr.gtgtgtanxiety, increased BP and HR, and
    decreased ETCO2.

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  • Intra spinal analgesia in patients receiving
    anticoagulants.

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  • The development of spinal hematomas is rare.
  • Such hematomas have been reported spontaneously
    in patients exposed neither to anticoagulants nor
    neuraxial block.
  • And have been reported in patients on low dose
    anticoagulant or neuraxial block alone.
  • And have been reported in combination of both
    therapies together.

59
Evidence of safety
  • Spinal hematomas in patients undergoing major
    conduction block while receiving low-dose heparin
    (and LMWH) is very rare.
  • Although epidural or spinal needle and catheter
    replacement and subsequent heparinization appears
    relatively safe, the risk of hematoma in patients
    who receive thrombolytic therapy is less defined.

60
Evidence of risk
  • In a study, 25 of patients with spontaneous
    spinal hematomas had a coagulopathy.
  • In another study, in47 of patients with an
    epidural catheter, spinal bleeding occurred after
    removal of catheter.

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Conclusions
  • Increasing the risk of hematomas with
    anticoagulants is not known.
  • The presence of anticoagulants, must be
    considered critical in the formation of spinal
    bleeding.
  • Whenever possible must correct defects in
    coagulation status before techniques.

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  • If LMWH is using, the risk of thromboemboli
    because of omitting anticoagulants is greater
    than formation a spinal hematoma in presence of
    LMWH.

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Patient-controlled epidural analgesia (PCEA)
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  • The amount of morphine needed in this technique
    is lesser than in continuous epidural infusion or
    I.V. PCA.
  • PCEA Fentanyl has been used successfully, but the
    results has no difference from I.V PCA.
  • Hydromorphone is both used, with a 4- to 5-fold
    decrease in needed dose compared with I.V.PCA.

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Combined spinal-epidural technique
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  • Has become popular in obstetrics and in operating
    room.
  • Advantage rapid onset of surgical anesthesia
    with availability to continue analgesia for post
    op. period.

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  • When an initial spinal anesthetic is initiated,
    testing the function of placed epidural cath. is
    impossible.
  • Spreading epidural solutions from the hole in the
    meninges, and subsequent respiratory depresion.
  • The combination routs of administering drug may
    cause respiratory depression.

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Role of the anesthesiologist in providing
intraspinal analgesia
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Intra-Articular analgesia
  • Following arthroscopic surgery, a combination of
    systemic Ketorolac and intra-articular
    bupivacaine decreased analgesic requirement and
    pain.

72
Non-opioid analgesics
  • 1-NSAID,s
  • 2-N2O.
  • 3-Ketamine.

73
NSAID,s
  • Advantages no evidence of unwanted sedation,
    absence of tolerance, reduction in opioid related
    side effects.
  • Act through inhibition of PG synthesis.
  • NSAID,s can replace opioids in most patients,
    both immediately after surgery or later (late
    analgesia with ketorolac is similar with
    morphine).

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  • In patients with PCA and parenteral ketorolac,
    opioid requirement, time to return of bowel
    function, and time to hospital discharge were
    reduced.
  • Side effects of Ketorolac bronchospasm, GI
    bleeding, altered platelet function,
    perioperative bleeding, and impairment of renal
    function.

75
Nitrous oxide
  • Useful, especially for painful experiences of
    short duration (dressing changes, debridements).
  • Rapid onset of analgesia and rapid recovery.
  • In concentrations of 30-50 is as potent as 10
    mg. I.M. morphine.
  • Anesthesia may occurgtgtgtrisk of aspiration.

76
  • Long term administration causes bone marrow
    suppression and leukopenia (reversible when
    detected early).
  • Entonox50mixture of N2O with oxygen.

77
Ketamine
  • Some concerns have limited its use
  • 1-sedation.
  • 2-emergence delirium.
  • 3-hallucinations.

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  • Side effects may reduce with
  • Opioid and scopolamine premedication.
  • Concomitant physostigmine.
  • Small doses of barbiturates, benzodiazepines, or
    deroperidol.
  • Ketamine may use in patients with opioid
    tolerance.

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Cryoanalgesia
  • Temp.s between -5 and -20causes disintegration
    of axons and breakdown of myelin sheaths while
    the perinurium and epinurium remain intact.
  • Is used most common for thoracotomy pain and
    hernia repair pain.
  • Residual neuropathic pain has been seen following
    cryoanalgesia.

80
Transcutaneous electrical nerve
stimulation(T.E.N.S.)
  • Uses both for chronic pain and acute
    perioperative pain.
  • Advantages absence of opioids side effects
    (resp. depression, sedation, nausea and vomiting,
    urinary retention)
  • It is simple, noninvasive and free of toxicity.

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  • The mechanism of analgesia by TENS is not known
    and it may be by
  • Modulation of nociceptive impulses in the spinal
    cord (gate control theory).
  • Activation of inhibitory area in the brain stem.
  • Stimulation of the release of endorphins, or a
    combination of these mechanisms.
  • A placebo effect may play a role.

82
  • Complications are uncommon
  • Skin irritation from gel or adhesives.
  • Contraindications
  • 1-pregnancy(first trimester).
  • 2-cardiac pacemakers.

83
Psychologic and other methods
  • After surgery patients may suffer discomfort
    due to headache, NG tubes, drains, IV catheters,
    or anxiety, fear, and insomnia.
  • Therapy of these problems may result in reporting
    of less pain.
  • Preoperative discussion, reassurance and
    provision information results in less anxiety,
    less opioid use and shorter hospital stay.

84
  • Relaxation tapes prior to surgery results in less
    analgesic use and a smoother recovery.

85
Perioperative analgesia in special populations
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Pediatric patients
  • Misconceptions about pain in children are common
    (e.g. children dont feel pain, or if it is felt
    it is not remembered.
  • Pain causes suffering and psychologic
    abnormalities in children of all age.
  • Special scales are available for young children
    (self reporting of pain).
  • In preverbal children, the interpretation of
    behavior must be used to estimate intensity of
    pain.

87
  • Because of fear of IM injections alternatives
    are sublingual, rectal and transdermal routs.
  • I.V. PCA is effective in children.
  • Caudal opioid analgesia can be used in children.
  • Regional techniques dorsal nerve block of the
    penis, or lidocaine jelly, or EMLA creams for
    circumcision, ilioinguinal and iliohypogastric
    nerve blocks for pains after orchiopexy and
    herniorrhaphy, etc.

88
  • NSAID,s are considered as adjuncts rather than as
    primary agents.

89
Elderly patients
  • The average age of surgical patients will
    increase in the future.
  • Older patients have more complex cases than
    younger.
  • PCA PCEA is ineffective in some elderly
    patients because of their reluctance.

90
  • Treatment of perioperative pain in elderly
    remains inadequate because
  • Fear of complications associated with treatment
    of pain.
  • Pain is reported less in elderly.

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  • NSAID,s may have benefits in elderly because
  • Different site of action that may be more
    effective.
  • Opioid sparing.
  • An additional anti-inflammatory effect.
  • But they have increased risk of side effects
    because of decreased renal clearancegtgtgtthey doses
    must be decreased.

92
Why elderly patients require less epidural
morphine?
  • 1-increased responsiveness of spinal cord opioid
    receptors.
  • 2-higher CSF morphine levels.
  • 3-Decreased effectiveness of neural barriers.
  • 4-Overall decrease in CNS function.

93
Advantages of regional anesthesia
  • Minimizing physiologic trespass.
  • Pharmacologic simplicity.
  • Reduced blood loss.
  • Fewer thromboembolic complications.
  • Reduced stress response.
  • Less confusion.
  • Less postoperative pain.

94
Postoperative delirium (POD)
  • Incidence7-61.
  • More common after orthopedic surgeries.
  • Most commonly appears on post operative day 3 or
    4.
  • Hallucinations in 40 of patients (often visual).
  • Negative outcomes increased hospital stay,
    increased demand on treatment resources, poorer
    postdischarge functional outcome.

95
  • Postoperative analgesia in elderly minimizes risk
    of POD.
  • Many causes of POD
  • Metabolic, toxic, environmental, or infectious
    insultes.

96
Patients with chronic pain and /or chronic opioid
use
97
  • General principles
  • 1-expect high self-reported pain scores.
  • 2-base treatment decision on objective pain
    assessment (deep breathing, coughing, etc.).
  • 3-recognize and treat nonnociceptive sources of
    suffering.
  • Continue opioids for as long as is appropriate
    for acute pain.

98
Addiction
  • A chronic disorder characterized by compulsive
    use of a substance resulting in physical,
    psychologic, or social harm to the user and
    continued use despite that harm.

99
Clinical triad suggestive of addiction
  • 1-high self-reported pain scores.
  • 2-high opioid use compared with other patients
    having similar procedures.
  • 3-a relative absence of opioid-induced side
    effects.

100
  • PCA is not good for providing basal opioid
    replacement.
  • PCA is good for extra opioids needed for
    postoperative pain.

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ROLE OF THE ANESTHESIOLOGIST IN PERIOPERATIVE
PAIN MANAGEMENT
102
  • Anesthesiologists are a logical choice to provide
    periop. Pain relief, because they are
  • 1-familiar with the pharmacology of analgesics
    and L.A.s.
  • 2-aware of short- and long-term effects of drugs
    given intraoperatively.
  • 3-knowledgeable about pain pathways and their
    interruption.
  • 4-are skilled in techniques available to provide
    superior pain control.

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Perioperative pain management services
104
  • Surgeons may be reluctant to allow other
    physicians to assume responsibility for pain
    management.
  • Departmental conferences and individual
    discussion are used to inform them of the
    potential benefits to their patients of a
    perioperative pain service.

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