Title: KEY CONCEPTS IN ACUTE PAIN MANAGEMENT SURGERY RESIDENTS Feb' 7, 2006
1KEY CONCEPTS IN ACUTE PAIN MANAGEMENT - SURGERY
RESIDENTS Feb. 7, 2006
- John Penning MD FRCPC
- Director Acute Pain Service
2Objectives
- 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
3Consequences 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
4Consequences 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
5Benefits 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
6The 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
7The 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
8What 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
9KEY 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!!
10Pain Pathways
11Acute 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
-
12Tissue Trauma
Cell Membrane Phospholipids
Phospholipase
Arachidonic Acid
COX
Cyclo-oxygenase
Endoperoxides
Toxic Oxygen Radicals
Thromboxane
Prostacyclin
Prostaglandins
13Case 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?
14Case 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
15Mortality From NSAID-Induced GI Complications vs
Other Diseases in US
Wolfe MM NEJM 1999 340 1888-99
16Pennings 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
17Analgesia with Opioids alone
- The harder we push with single mode analgesia,
the greater the degree of side-effects
Side-effects
Analgesia
18Multi-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
19Case 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.
20Case 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
21The 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
22The 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.
23NSAID 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
24The 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)
25The 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
26Cyclo-oxygenase inhibitors
Acetaminophen
Naproxen
Celecoxib
Ketorolac
Rofecoxib
27Cell Membrane Phospholipids
Phospholipase
Arachidonic Acid
COX-2
COX-1
Prostaglandins
Prostaglandins
Acute Pain
Gastric Protection
Inflammation
Platelet Hemostasis
Fever
Renal Function
28Why a COX-2 inhibitor?
- Equivalent analgesic efficacy with non-selective
COX-inhibitors - No effects on platelets!
- Better GI tolerability
- Less dyspepsia, less N/V
-
29Cyclo-oxygenase inhibitors
"COX-2 FOR U"
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31COX-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?
32Cyclo-oxygenase inhibitors
"Block the COX"
33Two 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
3436 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
3536 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
36The 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
37Opioids
- 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
38Opioids
- 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 -
-
39Opioids 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
40True 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
41Opioids 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
42Opioids Are they all the same?
- Morphine
- Hydromorphone (dilaudid)
- Oxycodone
- Meperidine (demerol)
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44Meperidine
Morphine
Atropine
Fentanyl
Bupivacaine
45Meperidine 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
46Meperidines 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
47Meperidine 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?
48When 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
49True or False?
- Codeine is a weak opioid?
- Codeine is inherently safer than the more potent
opioids?
50CODEINE A drug whose time has come and gone?
N Engl J Med 351 27 Dec. 30, 2004
51Problems 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
52Problems 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
53Codeine 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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58Potential 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
59Inhibitors of CYP2D6
- SSRIs (potent) especially PAXIL
- Cimetidine, Ranitidine
- Desipramine
- Propranolol
- Quinidine (potent)
- Viagra
- Many anti-biotics and chemo
60Instead of Tylenol 3 ?
- Acetaminophen 650 mg PO Q4H
- Morphine 10 20 mg PO Q4H prn
- OR
- Dilaudid 2 4 mg PO Q4H prn
61Why 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
62The 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
63The 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
64The 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.
65The 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
-
66Solution 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
67Solution to the T 3 limitations
Long Acting Opioid
Cox-inh Long Acting
For breakthough pain Regular opioid PO Q4h
prn Acetaminophen 650 mg PO Q4h prn
68Opioids
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
69Opioids 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
70When 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
71Case 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?
72Case 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.
73Case 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
74NMDA 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
75Hyperalgesia
Excitatory Mechanisms NMDA Agonists
PAIN
Inhibitory Mechanisms OPIOIDS
Analgesia
76NMDA 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.
77Case 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.
78Case 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.
79Case 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
80Opioids
- Issue
- With parenteral opioids the patient may
experience intolerable side effects before
adequate analgesia is attained
81Opioids
- CONCEPT 3
- Targeted regional
- administration of opioid
- results in enhancement of
- the therapeutic index (ratio
- of analgesia/side effects)
82Acute 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
83Neuraxial 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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85What 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
86What 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
87True 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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89Acute 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
90Case 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?
91Case 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!
92Case 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
93Epidural 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
94Epidural 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
95The 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
96The 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
97Is 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
98Is the Epidural Local Anesthetic causing the
hypotension?
- Intrathecal catheter migration
- Inadvertent overdose
- Un-masking of problem with the patient.
- Sensitive patient
99Is 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
100Management 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
101ACUTE 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.
102Conclusion 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
103Opioid 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
104Opioid 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)