Managing pain after surgery short
- 1. Managing Pain After Surgery Dr Yeo Sow Nam Director, The Pain Specialist, Mount Elizabeth Hospital & Founder and Past Director, Pain Management and Acupuncture Services, Singapore General Hospital MBBS (Singapore) MMED (Anesthesiology, S’pore) FANZCA (Anesthesiology, Aust/NZ) FFPMANZCA (Pain Medicine, Aust/NZ) FAMS, Registered Acupuncturist
- 2. Sites and mechanisms responsible for acute & chronic postsurgical pain Kehlet H, et al. Lancet 2006;367:1618-1625. 1. Denervated Schwann cells and infiltrating macrophages distal tp nerve injury produce local and systemic chemicals that drive pain signalling; 2. Neuroma at site of injury is source of ectopic spontaneous excitability; 3. Changes in gene expression in dorsal root ganglion; 4. Central sensitization at dorsal horn; 5. Modulation of pain transmission at brainstem; 6. Contributions from limbic system and hypothalamus; 7. Sensation of pain generated in cortex; 8. Genomic DNA predisposes (or not) to chronic pain 2
- 3. Postoperative pain vs persistent postsurgical pain Patient 1- PoP Severity of Pain Patient 2- PoP + PPP Surgery Time Acute- PoP Chronic- PPP Persistent Postsurgical Pain (PPP) Postoperative Pain (PoP) • Pain that persists beyond the usual course of • Pain resulting from the inflammation associated healing and is neuropathic in nature with surgical intervention • Pain is irresolvable and becomes chronic • Pain is resolvable and acute through irreversible changes to the pain pathway • All surgical interventions result in the • Incidence of PPP depends on surgery, intensity development of PoP of PoP, and genetic factors 3
- 4. Risk factors for development of persistent postsurgical pain1,2 1. Genetic susceptibility 2. Moderate to severe preoperative pain 3. Psychosocial factors 4. Age and sex 5. Poor surgical technique 6. Poorly controlled postoperative pain 1. Kehlet H, et al. Lancet 2006;367:1618-1625; 2. Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758. 4
- 5. Persistent postsurgical pain: Manifestation of neuropathic pain • Postsurgical chronic pain is the consequence of either ongoing inflammation or, much more commonly, a manifestation of neuropathic pain resulting from surgical injury to major peripheral nerves – If nerves are injured during surgery, a neuropathic component of the pain might develop immediately and then persist in the absence of any peripheral noxious stimulus or ongoing peripheral inflammation. This pain, once established, is likely to be resistant to COX-2 inhibitors. Kehlet H, et al. Lancet 2006;367:1618-1625. 5
- 6. Persistent postsurgical pain: Persistently overlooked • Development of chronic postsurgical pain may be the most overlooked negative sequel of elective operations – In the UK, surgery is the second most common reason patients give for having developed chronic neuropathic pain • Patients who present for surgery are often not told of this risk, and the surgeons and anaesthesiologists caring for them may not be aware of the prevalence of the problem Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758. 6
- 7. Estimated incidence of chronic postsurgical pain1,2 Estimated incidence Estimated incidence of Estimated US of chronic severe (disabling) pain surgical volumes postsurgical pain (1000s) Inguinal hernia repair 10% 2–4% 600 Lower limb 30–50% 5–10% 160 amputation Breast surgery 20–30% 5–10% 480 (lumpectomy or mastectomy) Thoracotomy 30–40% 10% 200 Total knee 12% 2–4% 550 arthroplasty Coronary artery 30–50% 5–10% 598 bypass surgery Caesarean section 10% 4% 220 1. Kehlet H, et al. Lancet 2006;367:1618-1625; 2. Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758. 7
- 8. Sub-optimal pain management can have economic consequences Re-admissions following day-care surgery Other • Mean charges for Surgical 17% 21% patients re-admitted due to pain were ADE $1,869 4,553 per 3% visit* Medical 14% • 38% of patients re- admitted for pain had undergone Bleeding orthopaedic Pain procedures 4% 38% N/V 3% *Mean inpatient re-admissions for pain $13,902 11,732 per visit ADE, adverse drug event N/V, nausea/vomiting Coley et al. J Clin Anesth 2002;14:349. 8
- 9. Persistent postsurgical pain: Potential for prevention • Avoidance of intraoperative nerve injury – Careful dissection – Reduction of inflammatory responses – Use of minimally invasive surgical techniques • Pre-emptive and aggressive multimodal analgesia – Afferent blockade, COX-2 inhibitors and opiates to alleviate inflammatory pain – Anti-neuropathic pain agents to prevent neuropathic pain Kehlet H, et al. Lancet 2006;367:1618-1625. 9
- 10. Multimodal analgesia: Rationale • Although opioid-based patient-controlled analgesia (PCA) is widely used as an effective method to control postoperative pain, it is associated with a high incidence of side effects, such as nausea, vomiting and respiratory depression1,2 • In recent years, a multimodal approach based on the combination of opioids and other adjuvant drugs (eg, nonsteroidal anti-inflammatory drugs, ketamine, local anesthetics and α2δ ligands) has been extensively attempted to decrease opioid-related adverse effects1,3 1. Kim JC, et al. Spine 2011;36:428-433; 2. Grass JA, et al. Anesthesiology 1993;78:642-648; 3. White PF. Curr Opin Investig Drugs 2008;9:76-82. 10
- 11. Multimodal analgesia • Current state of the art in the management of acute surgical pain • Strategy utilizing two or more modalities from the acute pain armamentarium to enhance analgesia and/or minimize risk of side effects • For multimodal analgesia to be maximized, the modes of analgesia should be procedure- and patient-specific Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758. 11
- 12. Benefits of multimodal analgesia Opioid • Decreased doses of each analgesic Potentiation • Improved anti-nociception due to synergistic/additive effects Paracetamol NSAIDs/coxibs Α2δ ligands • Decreased severity of side Ketamine effects of each drug Nerve blocks Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758; Kehlet H, Dahl JB. Anesth Analg 1993;77:1048-1056; Playford RJ, et al. Digestion 1991;49:198-203. 12
- 13. Pain sensitization by injury: Hyperalgesia and allodynia HYPERALGESIA Sensitized pain response 10 Pain intensity Normal 8 for stimulus X: pain response Sensitized Pain intensity pain response 6 Injury Pain intensity 4 for stimulus X: Normal pain response 2 0 X ALLODYNIA Stimulus intensity 13
- 14. Anti-hyperalgesic therapy: Opioid-sparing Sensitized Partially desensitized pain pain response 10 response ~30% Normal 8 reduction pain response Pain intensity 6 Anti- 4 Hyper- Opioid Opioid algesic 2 0 X Stimulus intensity 14
- 15. Prevention of persistent postsurgical pain Chronic postsurgical pain is a problem worldwide, but it is often overlooked or minimized. Several million patients each year may develop chronic pain due to nerve injury sustained during surgery. Identifying these patients and modeling a multimodal acute pain management plan to decrease the conversion of acute to chronic pain is an important therapeutic goal. Durkin B, et al. Expert Opin Pharmacother 2010;11:2751-2758. 15
- 16. Summary • Postsurgical chronic pain is a problem worldwide, but it is often overlooked or minimized • Postsurgical chronic pain is the consequence of either ongoing inflammation or, much more commonly, a manifestation of neuropathic pain resulting from surgical injury to major peripheral nerves • Identifying these patients and modeling a multimodal acute pain management plan to decrease the conversion of acute to chronic pain is an important therapeutic goal • Postsurgical chronic pain can be prevented by various ways • Recently, a multimodal approach has been extensively attempted to decrease opioid-related adverse effects 16