2. Preemptive Analgesia
PREEMPTIVE analgesia is an antinociceptive treatment
that prevents establishment of altered processing of
afferent input, which amplifies postoperative pain.
Preemptive analgesia has been defined as treatment
that:
(1) starts before surgery;
(2) prevents the establishment of central sensitization
caused by incisional injury (covers only the period of
surgery); and
(3) prevents the establishment of central sensitization
caused by incisional and inflammatory injuries.
3. Terms Commonly Used in Studies
on Preemptive Analgesia
Central sensitization —persistent postinjury
changes in the central nervous system that result
in pain hypersensitivity
Central hyperexcitability —exaggerated and
prolonged responsiveness of neurons to normal
afferent input after tissue damage
Preincisional treatment —treatment that starts
before an initial surgical incision
Postincisional treatment —treatment that starts
immediately after the end of operation.
4. History and progress in pre-emptive
analgesia
Pre-emptive analgesia would block the induction
of central neural sensitization brought about
by the incision and reduce the intensity of acute
postoperative pain ( proposed first by Crile and
later by Wall)
General anesthesia may attenuate the
transmission of afferent injury barrage from the
periphery to the spinal cord and brain, but it
doesn’t block the transmission
5. Treatment
1-Systemic opiods
Pure Agonists
Morphine, oxymorphone, meperidine,
hydromorphone, fentanyl
Partial agonists, mixed agonist-antagonists
Buprenorphine
Butorphanol
Pure Antagonists (reversal of agonists)
Naloxone
6. Conti…
2-Nonopioid analgesics:
ACETAMINOPHEN & NSAIDS like- Diclofenac, Ibuprofen
3-Regional anesthetic techniques .
a : Intrathecal analgesia.
b :Epidural analgesia: Provides superior pain
relief and attenuate the stress response to surgery,
particularly continuous infusion during and after
surgery.
7. Conti…
Combined use of epidural local anesthetics and
adjuvants provides introperative analgesia and
postoperative pain effectively
4-Peripheral nerve blocks
5-Cryoanalgesia: is a procedure used to
temporarily block nerve conduction along
peripheral nerve pathways. The
procedure, which involves insertion of a
small probe to freeze the target nerve
8. POST-OPERATIVE PAIN
Acute Post-operative Pain
Surgery
Tissue trauma or nerve injury
Inflammation due to release of inflammatory mediators
Hyperalgesia and Allodynia (increased response of neurons)
9. Chronic Post-surgical Pain
Pain lasting form more than 1 month after surgery
Risk factors for CPSP
1. Repeat surgery
2. Catastrophizing
3. Anxiety
4. Genetic predisposition
5. Radiation therapy to that area
6. Moderate to severe post-operative pain
7. Surgical approach with risk of nerve damage
8. Neurotoxic chemotherapy
9. Depression
10. POST-OPERATIVE MANAGEMENT
OPOIDS – MORPHINE (PROTOTYPIC
AGENT)
IV, IM ,ORAL AND TRANSDERMAL ROUTES
MODERATE POTENCY,SLOW ONSET AND INTERMEDIATE
DURATION OF ACTION.
OTHER OPOIDS COMMONLY USED –
1. HYDROMORPHONE
2. FENTANYL
3. MEPERIDINE
4. TRAMADOL
11. NON-OPOIDS ANALGESICS
DRUG:
Acetaminophen (paracetamol)-Effective analgesic
for acute pain
Nonselective NSAIDs (eg, ibuprofen, ketorolac,
naproxen)-Effective in treatment of acute
postoperative pain
COX inhibitors(Aspirin)-Effective in treatment of
acute postoperative pain
Ketamine: subanesthetic doses-Effective adjuvant
for pain associated with central sensitization (eg,
severe acute pain, neuropathic pain, opioid-
resistant pain)
12. Antidepressants and selective serotonin
reuptake inhibitors
Useful for acute neuropathic pain
Anticonvulsants (Gabapentin and pregabalin)-Reduce
postoperative pain, opioid requirements, and incidence of
vomiting, pruritus, and urinary retention, but increase risk of
sedation
May be useful for acute neuropathic pain (based on experience
with chronic neuropathic pain)
IV lidocaine infusion- Opioid sparing; reduced pain scores, nausea,
vomiting .
a2 Agonists (clonidine, dexmedetomidine)-Improves perioperative
opioid analgesia. Decreased opioid requirements and opioid side
effects
Side effects: sedation, hypotension