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Post operative pain management. Jutarat Luanpholcharoenchai. Learning objects. Pain pathway Physiologic response to pain Pain evaluation & assessment Pain management & monitoring Complication. Pain.
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Post operative pain management Jutarat Luanpholcharoenchai
Learning objects • Pain pathway • Physiologic response to pain • Pain evaluation & assessment • Pain management & monitoring • Complication
Pain • unpleasant sensory & emotional experience that is associated with actual or potential tissue damage.
Pain pathway • Peripheral sensitization : mechanical, thermal, chemical stimuli : PGE2 ↓nociceptor threshold ↑response to noxious stimuli
Pain pathway • Lateral pain system • Lateral thalamic nuclei • Location, duration, intensity Medial pain system central, medial thalamus &limbic system unpleasant, defense response
Pain pathway • Central sensitization : C- fibers release glutamate binding to NMDA receptor : second messenger cascade hyperexcitable spinal cord neuron ↑ response from injuries region & adjacent region “secondary hyperalgesia” “hyperalgesia” & “allodynia”
Physiologic response • Cardiovascular : HR, BP ,PVR, ↑myocardial O2 consumption MI, DVT, pulmonary embolism • Respiratory :⇩ lung volume atelectasis :⇩cough, sputum retention infection, hypoxemia • Gastrointestinal : ⇩gastric & bowel motility, :risk of bacterial transgression of bowel wall
Physiologic response • Musculoskeletal :muscle spasm, immobility risk DVT :muscle wasting prolong recovery • Central nervous : central sensitization chronic pain • Psychological : anxiety, fear, sleep deprivation, leading to pain
Physiologic response • Neuroendocrine : catabolic hormone (glucagon, growth hormone, vasopressin, aldosterone, renin angiotensin) hyperglycemia, impaired wound healing : ⇩anabolic hormone(insulin, testosterone)
Surgical pain ReviewMultimodal strategies to improve surgical outcome The American Journal of Surgery 183 (2002) 630–641
Surgical pain Major surgery Thoracotomy Major abdominal surgery Knee surgery Surgical procedure Moderate surgery Hip replacement Hysterectomy maxillofacial Minor surgery Herniotomy Varicose vein Gynecological laparotomy Paracetamol /NSIADs Epidural anesthesia systemic opioids PCA Paracetamol /NSIADs +Wound infiltration Peripheral nerve block Systemic opioids PCA Paracetamol /NSIADs / weak opiods Wound infiltration Peripheral nerve block Treatment modality
Surgical outcome ReviewMultimodal strategies to improve surgical outcome The American Journal of Surgery 183 (2002) 630–641
Pain management 1. Patient education 2. Drugs & non drugs treatment 3. Monitoring requirement 4.Treatment of side effects
Pain management • Preemptive analgesia & Multimodal analgesia • ⇩ doses of each analgesic • Improved actinociception due to synergistic/additive effects • may⇩ reduce severity of side effect of each drugs
Multimodal analgesia Opioid Anti inflammatory agents Alpha 2 agonist Local anesthetics Opioid Anti inflammatory agents Alpha 2 agonist Local anesthetics Opioid Anti inflammatory agents
Pain evaluation & assessment Nociceptive / Inflammatory pain :Somatic; sharp, hot, sting well localized :Visceral; dull, cramping, colicky poorly localized, referred pain
Pain evaluation & assessment Non- nociceptive pain :Neuropathic Hx of nerve damage, burning, shooting, stabbing, allodynia, hyperalgesia, dysesthesias : Psychogenic pain
Pain evaluation • Pain history • Site of pain • Conditions associated with pain onset • Character :intensity , associated symptoms • Current & prior treatment • Relevant medical history • Other patient factors
Pain evaluation • Physical examination • Psychological examination
Pain management guideline Pain symptom Mild Moderate severe intensity Drug selection Constant moderate to severe pain Intermittent pain prn short acting analgesics Long acting analgesics +prn short acting analgesics
Factors influencing analgesic requirements • Age : elderly request smaller doses • Pre-operative analgesic use. • Coexisting medical conditions • Preoperative patient education • Site of operation
Treatment … • Pharmacologic • Opioid • Non opioid • Adjuvant
Opioids • Essential element of pain management • Mechanism • Action on opioid receptor • Located mainly in spinal cord& brain stem, some in peripheral tissue
Opioids receptors Clinical effect Analgesia, sedation, euphoria Resp. depression, physical dependence Spinal analgesia, resp. depression Analgesia, resp. depression Dysphoria, hallucination, tachycardia hypertension Receptors Mu (μ or OP3) μ1 μ2 Kappa (κ or OP2) Delta (δ orOP1) Sigma(σ)
Opioids 1.Agonists : stimulate receptor : no ceiling effect ( no limit mg/kg) : moderate to severe pain : Codiene, morphine, pethidine, fentanyl, methadone
Opioids 2.Partial agonists : ceiling effects eg.buprenorphine
Opioids 3. Agonists-antagonists : agonist-κ or σ receptor but antagonist to μ receptor : can used in mild to moderate pain : ceiling effects : precipitate withdrawal in opioids dependent : pentazocine, nalbuphine
Opioids 4. Antagonists : competitive antagonist to all opioid receptors eg. naloxone
Morphine :standard treatment : metabolism : liver M-3-G : no analgesic property M-6-G : more potent than morphine(2X) : histamine release
Meperidine :atropine like effect : tachycardia ,dry mouth : metabolism liver Normeperidine CNS excitation : shivering treatment : interaction with MAOI hyperpyrexia, convulsion ,hypertension ,coma
Fentanyl : rapid onset & short duration : inactive metabolite : no histamine release :100X potent than morphine
Codeine : weak opioids : orally plus with paracetamol “ TWC” : mild to moderate pain. :Doses 15-60 mg 4 hourly (with a maximum of 300 mg daily)
Naloxone : Px opioid intoxication : dilute to 10 ml. titration : side effect : withdrawal symptoms, hypertension, tachycardia, pain, pulmonary edema
Naloxone Respiratory depression & somnolence : 1-4 mcg/kg repeat q 2-3 min : 3-5 mcg/kg/hr continuous infusion Urinary retention & Pruritus : 1-2 mcg/kg Nausea vomitting : 0.5-1 mcg/kg
Basic requirement for opioid Route of administration : safe, effective titration Initial prescription : appropriated dose : used of dose interval : monitoring of pain & sedation score : alteration of subsequence dose Aim : patient comfort, sedation score <3
Goal! treatment : Right opioids : Right route : Right dose : Right interval
Opioids Administration Analgesic corridor
Opioids Administration Around the clock
Opioids dose Breakthrough pain Promt Short action easy to give
Opioids Administration prn for pain q …
Opioids Administration 1.Intravenous continuous drip Side effects Analgesic corridor PAIN
Opioids Administration 2.Intravenous q 4 hr 3.Intramuscular q 4 hr
Opioids Administration 4. IM prn q 6 hr 5. IM prn q 2 hr