Preemptive analgesia

pre-emptive analgesia and post operative pain management

1. Saurabh Gupta VHK-1435 Pre-emptive Analgesia & Post Operative Pain Management General Veterinary Surgery, Anesthesiology & Diagnostic Imaging

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 Repeat surgery Catastrophizing Anxiety Genetic predisposition Radiation therapy to that area Moderate to severe post-operative pain Surgical approach with risk of nerve damage Neurotoxic chemotherapy 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 – HYDROMORPHONE FENTANYL MEPERIDINE 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

13. Thank you