Lecture Title: Acute Pain Management بسم الله الرحمن الرحيم Lecture Title: Acute Pain Management Lecturer name: Lecture date:

Lecture Objectives.. Students at the end of the lecture will be able to: Learn a common approach to emergency medical problems encountered in the postoperative period. Study post-operative respiratory and hemodynamic problems and understand how to manage these problems. Learn about the predisposing factors, differential diagnosis and management of PONV. Understand the causes and treatments of post-operative agitation and delirium. Learn about the causes of delayed emergence and know how to deal with this problem. Learn about different approaches of post-Operative pain management

Postoperative care - Post Anesthesia Care Unit “PACU”

PACU Design should match function Location: Monitoring equipment Close to the OR. Access to x-ray, blood bank & clinical labs. Monitoring equipment Emergency equipment Personnel

Admission to PACU Steps: Coordinate prior to arrival, Assess airway, Administer oxygen, Apply monitors, Obtain vital signs, Receive report from anesthesia personnel.

PACU - ASA Standards Standard I Standard II Standard III Standard IV All patients should receive appropriate care Standard II All patients will be accompanied by one of anesthesia team Standard III The patient will be reevaluated & report given to the nurse Standard IV The patient shall be continually monitored in the PACU Standard V A physician will signing for the patient out of the PACU

Patient Care in the PACU Admission Apply oxygen and monitor Receive report Monitor & Observe & Manage  To Achieve Cardiovascular stability Respiratory stability Pain control Discharge from PACU

Monitoring in the PACU Baseline vital signs. Respiration Circulation RR/min, Rythm Pulse oximetry Circulation PR/min & Blood pressure ECG Level of consciousness Pain scores

Initial Assessment Color Respiration Circulation Consciousness Activity

Aldrete Score 2 1 Score Activity Respiration Circulation Consciousness Oxygen Saturation 2 Moves all extremities Breaths deeply and coughs freely. BP + 20 mm of preanesth. level Fully awake Spo2 > 92% on room air 1 Moves 2 extremities Dyspneic, or shallow breathing BP + 20-50 mm of preanesth. level Arousable on calling Spo2 >90% With suppl. O2 Unable to move Apneic BP + 50 mm of preanesth. level Not responding Spo2 <92%

Common PACU Problems Airway obstruction Hypoxemia Hypoventilation Hypotension Hypertension Cardiac dysrhythmias Hypothermia Bleeding Agitation Delayed recovery “PONV” Pain Oliguria

1. Airway Obstruction Most common: tongue fall back  posterior pharynx May be foreign body Inadequate relaxant reversal Residual anesthesia

Management of Airway Obstruction Patient’s stimulation, Suction, Oral Airway, Nasal Airway, Others: Tracheal intubation Cricothyroidotomy Tracheotomy

2. Hypoventilation Residual anesthesia Post oper - Analgesia Narcotics Inhalation agent Muscle Relaxant Post oper - Analgesia Intravenous Epidural

Treatment of Hypoventilation Close observation, Assess the problem, Treatment of the cause: Reverse (or Antidote): Muscle relaxant  Neostigmine Opioids  Naloxone Midazolam  Anexate

3. Hypertension Common causes: e.g. Hypertensive patients Pain Full Bladder Hypertensive patients Fluid overload Excessive use of vasopressors

Treatment of Hypertension Effective pain control Sedation Anti-hypertensives: Beta blockers Alpha blockers Hydralazine (Apresoline) Calcium channel blockers

4. Hypotension Decreased venous return Hypovolemia, Sympathectomy,  fluid intake  losses Bleeding Sympathectomy, 3rd space loss, Left ventricular dysfunction

Treatment of Hypotension Initially treat with fluid bolus, + Vasopressors, + Correction of the cause

5. Dysrhythmias Secondary to Hypoxemia Hypercarbia Hypothermia Acidosis Catecholamines Electrolyte abnormalities.

Treatment of Dysrhythmia Identify and treat the cause, Assure oxygenation, Pharmacological

6. Urine Output Oliguria Treatment: Hypovolemia, Surgical trauma, Impaired renal function, Mechanical blocking of catheter. Treatment: Assess catheter patency Fluid bolus Diuretics e.g. Lasix

7. Post op Bleeding Causes: Usually Surgical Problem, Coagulopathy, Drug induced

Treatment of Post op Bleeding Start i.v. lines  push fluids Blood sample, CBC, Cross matching, Coagulopathy Notify the surgeon, Correction of the cause

8. Hypothermia Most of patients will arrive cold Treatment: Get baseline temperature Actively rewarm Administer oxygen if shivering Take care for: Pediatric, Geriatric.

9. Altered Mental Status Reaction to drugs? Pain Full bladder Drugs e.g. sedatives, anticholinergics Intoxication / Drug abusers Pain Full bladder Hypoventilation Low COP CVA

Treatment of Altered Mental Status Reassurances, Always protect the patient, Evaluate the cause, Treatment of symptoms, Sedatives / Opioids if necessary.

10. Delayed Recovery Systematic evaluation Pre-op status Intraoperative events Ventilation Response to Stimulation Cardiovascular status

Delayed Recovery The most common cause: Hypothermia, Residual anesthesia  Consider reversal Hypothermia, Metabolic e.g. diabetic coma, Underlying psychiatric problem CVA

11. Postoperative Nausea & Vomiting “PONV” Risk factors Type & duration of surgery, Type of anesthesia, Drugs, Hormone levels, Medical problems, Autonomic involvement.

Prevention of PONV NPO status Dexamothasone, Droperidol, Metoclopramide, H2 blockers, Ondansetron, Acupuncture

12. Postoperative Pain

12. Postoperative Pain Causes: Others: Incisional Skin and subcutaneous tissue Laparoscopy Insuflation of Co2 Others: Deep cutting, coagulation, trauma Positional nerve compression, traction & bed sore. IV site needle trauma, extravasation, venous irritation Tubes drains, nasogastric tube, ETT Surgical complication of surgery Others cast, dressing too tight, urinary retention

PAIN MEASUREMENTS Subjective Objective Uni-Dimensional Multidimentional Behavioral. Physiological. Neuro-endocrinal. Algometry. VRS, VAS & NRS. Facial expression. McGill P Q, Pain Inventory. ACUTE PAIN Chronic Pain Both

Visual Analogue Scale (VAS) Numeric Rating Scale (NRS) Pain Scores Visual Analogue Scale (VAS) 0 10 Numeric Rating Scale (NRS)

Wong-Baker “Faces Scale” Verbal scale Wong-Baker “Faces Scale”

ACUTE POSTOPERATIVE MANAGEMENT TOOLS Pharmaco - Therapy Regional Techniques Non Opioid Analgesics NSAADs Analgesic /Antipyretic Analgesic/Anti-inflam/Antipyretic NSAIDs Non-selective COX inhibitors Selective COX-2 inhibitors Opioids Weak Opioids. Strong Opioids. Mixed agonist-antagonists Adjuvants -2 Agonists LA SP inhibitors NMDA inhibitors Anticonvulsant / Antidepressants Calcitonin Relaxants Cannabinoids Others Local infiltration Wound perfusion Intra-abdominal inj. of LA/Analg. Intercostal & Interpleural Paravertebral USG-RA: e.g. TAP Neuraxial: Epidural: Thoracic Lumbar Spinal Single shot CSA CSE

WHO Ladder Updated WHO IV Interventional WHO III Strong opioids Severe pain (7-10) WHO III Strong opioids ± Adjuvant Pain Persists or Increases Moderate pain (4-6) WHO class II Weak opioids ± Adjuvant Mild pain (0-3) By the mouth By the clock By the ladder WHO class I NSAIDs ± Adjuvant

WHO (I) Non Opioid Analgesics NSAADs Analgesic / Anti-inflam / Antipyretic / Anticoagulant ASA Analgesic /Antipyretic Paracetamol NSAIDs Non-selective COX inhibitors: Diclofenac & Ketoprofen Selective COX-2 inhibitors Celecoxib & Rofecoxib Severe pain (7-10) WHO class I NSAIDs WHO class II Weak opioids WHO III Strong opioids Mild pain (0-3) Moderate pain (4-6) ± Adjuvant

Scientific Evidence – NON OPIOID ANALGESICS Paracetamol: is an effective analgesic for acute pain; the incidence of adverse effects comparable to placebo (Level I [Cochrane Review]). Paracetamol / NSAIDs given in addition to PCA Opioids   Opioid consumption (Level I). NSAIDs: are effective in the treatment of acute postoperative (Level I ). With careful patient selection and monitoring, the incidence of renal impairment is low (Level I [Cochrane Review]). NSAIDs + Paracetamol improve analgesia compared with paracetamol alone (Level I). Acute Pain Management - Scientific Evidence - AAGBI Guidelines 2010

WHO Ladder II - Weak Opioids: Tramadol: Tramadol : Morphine: Parenteral = 1 : 10 & Oral = 1 : 5 Dose: 200 – 400 mg/d Codeine: Metabolized to morphine. Codeine : Morphine = 1 : 10 Dextro-propoxyphene: Methadone Derivative Prolongation of Q-T interval. They can relief pain when we increase the dose but with significantly higher incidence of side effects. Members are: Tramadol: Equi-potency to morphine: 1:10 Parenteral. 1:5 Oral. Codeine: Metabolized to morphine. Equi-potency to morphine: (1:10). Hydrocodone: Metabolized to Hydromorphine. Equi-potency to morphine: (1:2). Dextro-propoxyphene: Methadone Drivative, can cause prolongation of Q-T interval. Tramadol hydrochloride: Dose is 100 mg. Equivalent to 100 mg. pethidine. Less postoperative respiratory depression. Nausea and vomiting is the prominent side effect. Efficient in reduction of postoperative shivering. It is always needed to start with weak opioids before giving strong opioids particularly in cancer patients. They are weak as their affinity to opioid receptors is very much less than strong opioids. Codeine has to be metabolized to morphine in the body to act. A process which is dependant of metabolic enzymes mainly the Cytochrome oxidase enzyme. Enzyme inhibitors as cimetidine, quinidine, and antifungal drugs can block this reaction and inhibit codeine analgesia. Dose of codeine is 200 mg, every 4-6 hours.Dose of dihydrocodiene is 10-20 mg every 4-6 hours Tramadol on the other hand, is a very weak opioid analgesic. Its analgesia is dependant on potentiation by its serotonergic and noradrenergic effect. It is only potent as an analgesic because of this potentiation that makes it as potent as pethidine. It is also characterized by the absence of tolerance. A very useful weak opioid particularly effective in neuropathic pain. Dose is 50 mg-100 mg every 6 hours. Dextropropxyphene: is a weak opioid, its maine side effect is persistent constipation.Dose is 300 mg every 4-6 hours. Severe pain (7-10) WHO class I NSAIDs WHO class II Weak opioids WHO III Strong opioids Mild pain (0-3) Moderate pain (4-6) ± Adjuvant

Scientific Evidence – WEAK OPIOIDS Tramadol: has a lower risk of respiratory depression & impairs GIT motor function < other opioids (Level II). is an effective treatment for neuropathic pain (Level I [Cochrane Review]). Dextropropoxyphene: has low analgesic efficacy Acute Pain Management - Scientific Evidence - AAGBI Guidelines 2010

WHO Ladder III - Strong Opioids Morphine: Sedation PONV Respiratory Depression Fentanyl Rapid action, Short duration. Fentanyl : Mophine = (1:10) Pethidene: Active metabolite:  t½ . Prolongs Q-T interval. Pethidine : Mophine = (1:10) Hydromorphone: Powerful, rapidly acting. Release is in distal gut. Hydromorphone : Morphine = 1 : 5 Severe pain (7-10) WHO class I NSAIDs WHO class II Weak opioids WHO III Strong opioids Mild pain (0-3) Moderate pain (4-6) ± Adjuvant Morphine: available in. Immediate release( 4 hourly). Controlled release (12-hourly). Sustained release (24-hour dosing). Morphine is a universal opioid agonist, binding to cerebral OR4 is responsible for tolerance. Oxycodone: Active on k-opioid receptors: important in visceral and Neuropathic pain. Double phase of action of SR form: a rapid initial followed by a slow phase. Equianalgesic dose with morphine for opioid rotation is 2:3. Fentanyl: (available in a TTS & Transmucosal formulation): No first path liver metabolism. Has a specific m & k-opioid receptor binding effect, and no OR4 binding. Opioid receptor side effects are generally 1/3 of morphine. Pharmacokinetic and Pharmacodynamic Considerations 1. With opioid drugs, four to five half-lives are required to approach steady state plasma concentrations. Methadone,and levorphanol have relatively long half-lives: Methadone: from 12 to more than 100 hours. Levorphanol : from 12 to 16 hours. Many days may be required to stabilize on methadone after a dose is selected, with possible cumulative toxicity. 2. Transdermal fentanyl has a long apparent half-life (about 24 hours), which results from continued absorption of drug from a subcutaneous depot after the patch is removed. Controlled-release formulations reach steady state relatively quickly. The transdermal system, for example, usually approaches steady state after 2 to 3 days and the controlled-release morphine and oxycodone preparations approach steady state after 1 to 2 days. Analgesic duration following a dose is only loosely related to half-life: Most opioids require a dosing interval of 3 to 4 hours.

WHO Ladder IV – Regional Anesthetic Techniques Local infiltration Wound perfusion Intra-abdominal LA Intercostal Interpleural Paravertebral USG - RA: e.g. TAP Neuraxial: Epidural: Thoracic Lumbar Spinal Single shot CSA CSE WHO III Strong opioids Mild pain (0-3) Moderate pain (4-6) Severe pain (7-10) ± Adjuvant WHO IV Interventional WHO class II Weak opioids WHO class I NSAIDs

Neuraxial (Spinal / Epidural) (LA / Opioids / others) Advantages: Provide prolonged & effective analgesia Side effects Respiratory depression. N/V. Pruritis. Urinary retention.

WHO Algorithm for Management of Pain + Multidisciplinary: Adjuvant therapy. Psychotherapy. Physioltherapy. Causal diag. & ttt. Neuraxial LA Opioids WHO III Strong opioids Plexus block Paravertebral / PNB WHO class II Weak opioids Non-pharmacological LA infiltration WHO class I NSAIDs

Management Algorithm for Postoperative Pain Diagnosis Procedure Specific Pain manag. Preventive / Preemptive Pain Assessment ttt of Pain and Co morbidities 1ry Treatment Supportive Treatment Pharmacotherapy Psychological ttt. Interventional Physical / Rehab.

PACU Discharge Criteria Fully Awake, Patent airway, Good respiratory function, Stable vital signs, Patency of tubes, catheters, IV’s Pain free, Reassurance of surgical site.

Postanesthesia Discharge Scoring System Vital Signs (PR & ABP) Activity PONV Pain Surgical Bleeding 2: Within 20% of preoperative baseline 2: Steady gait, no dizziness 2: Minimal: treat with PO meds 2: Acceptable control per the patient; controlled with PO meds 2: Minimal: no dressing changes required 1: 20-40% of preoperative baseline 1: Requires assistance 1: Moderate: treat with IM medications 1: Not acceptable to the patient; not controlled with PO meds 1: Moderate: up to 2 dressing changes 0: >40% of preoperative baseline 0: Unable to ambulate 0: Continues: repeated treatment 0: Severe Uncontrolled pain 0: Severe: more than 3 dressing changes

Reference book and the relevant page numbers..

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