Anesthesia pain management

1. Acute Pain
Management

2. Objectives/Discussion Topics
 Appropriate assessment of acute pain
 Concept of multi-modal analgesia
 Indications and side effects of analgesics
 How to rationally prescribe opioids
 side effects and complications of opioids
 Special populations ie elderly, opioid tolerant
 Neuraxial/regional analgesia
 side effects and complications of neuraxial analgesia
 interaction of various anticoagulant medications and
neuraxial analgesia

3. Goal
 To provide patients with a level of pain control that
allows them to actively participate in recovery
 This level will be individual to each patient
 To minimize nausea and vomiting
 To minimize other side effects of analgesics
 Sedation
 Ileus
 Weakness
 Hypotension

4. Why all the fuss?
 Pain is a miserable experience
 Pain increases sympathetic output
 Increases myocardial oxygen demand
 Increases BP, HR
 Pain limits mobility
 Increases risk for DVT/PE
 Increases risk for pneumonia, atelectasis secondary
to splinting

5. Assessment
 Intensity
 Location
 Onset
 Duration
 Radiation
 Exacerbation
 Alleviation

6. How do we do it?
 Multimodal analgesia: Several analgesics with different
mechanisms of action, each working at different sites in the
nervous system
 Acetaminophen
 Non-steroidal anti-inflammatory drugs (NSAIDs)
 Opioids
 Anticonvulsants
 Antidepressants
 Local anaesthetics
 NMDA Antagonists
 Non-pharmacologic methods

7. OPIOIDS
Efficacy is limited by Side-Effects
 The harder we “push” with single mode analgesia, the greater
the degree of side-effects
Analgesia
Side-effects

8. Multimodal Analgesia
 Lower doses of each drug can be used therefore minimizing
side effects
 With the multimodal analgesic approach there is additive
or even synergistic analgesia, while the side-effects profiles
are different and of small degree (Pasero & Stannard, 2012).
Analgesia
Side-effects

9. Systemic Analgesia
 Opioids
 Potent analgesics
 Drug of choice for moderate to severe pain
 Unfortunately, they are often the only drug ordered
 Side effects:

10. Opioids
 10 fold variability between patients
 All opioids have same side effects but
efficacy:side effect ratio is different for everyone
 Stick with what works and keep it simple
 Always by mouth if possible
 Avoid pro-drugs ie. codeine
 Avoid combo preparations

11. Equianalgesia
Opioid PO Parenteral
(IV/SC)
Morphine 10 mg 5 mg
Codeine ~ 60-100mg (4-
fold variability)
N/A
Hydromorphone 2 mg 1 mg
Oxycodone 5 mg N/A

12. NALOXONE (Narcan)
 Mu opioid antagonist
 Dilute 1 mL of naloxone 0.4 mg/mL (ie. one
vial) with 9 mL of NS for a total of 10 mL of
solution and a final concentration of
0.04 mg/mL
 Administer 0.04 mg at a time until reversal of
respiratory depression has been achieved, ie.
when they’re sitting up awake and talking to you!

13. NALOXONE (Narcan)
 REMEMBER: the half-life of naloxone is only
30 minutes, while the half-life of opioid is 2-3 hr
so you may have to repeat dosing OR place pt
on naloxone infusion until all opioid has been
metabolized to prevent further respiratory
depression

14. Elderly Patient
 Pronounced effect therefore, lower doses
 Cognitive dysfunction is a major issue
 Organ dysfunction/insufficiency affects
metabolism
 Interaction with other medications, increased
incidence of polypharmacy

15. Addiction
 Primary, chronic, neurobiologic disease, with
genetic, psychosocial, and environmental factors
influencing its development and manifestations.
 Characterized by behaviors that include one or
more of the following:
 impaired control over drug use
 compulsive use
 continued use despite harm
 craving
Definitions Related to the Use of Opioids for the Treatment of Pain. American Academy
of Pain Medicine; American Pain Society; American Society of Addiction Medicine. 2001.

16. Physical Dependence
 State of adaptation that is manifested by a drug
class-specific withdrawal syndrome that can be
produced by abrupt cessation, rapid dose
reduction, decreasing blood level of the drug,
and/or administration of an antagonist

17. Tolerance
 The body's physical adaptation to a drug:
 Greater amounts of the drug are required over time
to achieve the initial effect as the body adapts to the
intake

18. Pseudo Addiction
 Term used to describe patient behaviors that
may occur when pain is undertreated
 May become focused on obtaining medications,
"clock watch," seem inappropriately "drug
seeking."
 Illicit drug use and deception can occur in the
patient's efforts to obtain relief
 Distinguished from true addiction in that the
behaviors resolve when pain is effectively
treated.

19. NSAIDS
 Work at site of tissue injury to prevent the
formation of the nociceptive mediators
Prostaglandins
 Can decrease opioid use ~30% therefore
decreasing opioid-related side effects
 Minor surgeries can use NSAIDs instead of
opioids to completely eliminate opioid-
associated side effects
 Side effects:

20. NSAIDS
 Newer NSAIDS selectively (primarily) inhibit
cyclooxygenase-2 (COX-2) which is induced by
surgical trauma with minimal effect on COX-1
which is responsible for GI and platelet side
effects
 Celecoxib (Celebrex)

21. Neuraxial Techniques
Who Gets Them?
Patient factors:
 Low pain tolerance, opioid tolerance
 Sleep apnea
 Narcolepsy
 Obesity
 COPD
 Cardiac disease
 Elderly – those at risk for post-operative cognitive
dysfunction

22. …….

25. Epidural Infusions
 Used for major surgery ie. oncologic TAH BSO,
thoracotomy
 Ideally placed pre-operatively and used in
combination with a GA for surgery and
continued ~ 2 days
 Usually patient is tolerating diet and ambulation
to chair when epidural is D/C

26. Ideal Epidural Infusions
 When placed at the level of the incision and with a constant
infusion of LA and opioid:
 Minimal or no pain at all, particularly with movement
 No motor block
 Can ambulate
 Speedier return of bowel function
 With more LA and less opioid –Cochrane review 2003
 Less nausea
 Less sedation
 Less delerium
 Do not require supplemental IV opioids and associated side effects
 Less pulmonary complications
 Quicker extubation, better oxygen saturation, less pneumonia

27. Side Effects of Epidural Infusions
 Hypotension
 LA causes a sympathectomy which leads to
vasodilatation
 Mild volume depletion, which can normally be
compensated for with vasoconstriction, will be
unmasked with an epidural
 Pts require adequate volume status with an epidural

28. Side Effects
 Hypotension
 Pts will initially c/o dizzyness, lightheadedness and
nausea when sitting up or standing
 Can document orthostatic hypotension
 Will then progress to supine hypotension if not
corrected
 Major problem POD #1 when 3rd spacing still
occurring, minimal IV fluids infusing and pt NPO

29. Side Effects
 Leg weakness or numbness
 Can occur if catheter is too low (low thoracic or lumbar) or if
it is one-sided
 Inhibits ambulation and distressing to pt therefore must be
fixed
 Infusion can be adjusted or catheter pulled back
 Must be addressed as this is the first sign of epidural
hematoma leading to permanent paralysis

30. Complications
 Post dural puncture headache 1:100
 Only if dura is unintentionally punctured
 More likely in younger people
 Infection
 Some reports of epidural abscess as high as 1:1900
 Usually just superficial skin infections
 Increased risk in immunosuppressed

31. Complications
 Epidural hematoma
 Most feared complication
 Incidence of 1:180 000 – 1:220 000
 Increased with heparin, age, gender, ASA, NSAIDs,
traumatic placement, spinal stenosis
 Leg weakness, numbness and bladder/bowel
disturbance are first signs
 If not evacuated within 8-12 hours, usually leads to
permanent paralysis

32. Complications
 Epidural Hematoma
 Risks
 Abnormal coagulation
 Elderly
 Female
 Debilitated patients
 Traumatic insertion
 Unknown spinal pathology

33. Complications
Anticoagulation and Epidurals:
 ASA – OK
 NSAIDS – OK
 UFH 5000 sc bid – OK if no other antiplatelets
 UFH 5000 sc tid – sort of OK, but not really (according to
ASRA)
 LMWH (Dalteparin)– increased risk – not really OK
 IV heparin – not OK
 Clopidigrel, ticlodipine – not OK
 Coumadin – not OK

34. Ideal Patient Care
 Surgeons, APMS, nursing all working for same
goal
 Pre-operative optimization
 Intra-operative care
 Post-operative
 Ambulation, pain, bowels, voiding
Improved patient recovery

35. Acute Pain Management Service
(APMS)
 Consulting service, mostly post-op patients
 PCAs, non-labour epidurals, regional techiques
 Don’t need to co-sign our orders
 Can’t order any analgesics, anti-emetics,
antihistamines, neuropathic pain agents, or
sedatives while patient being followed by APMS
 “Suggest Orders” once APMS signs off DO
need to be co-signed