Pre-op Interventions to Mitigate Post-op Acute and Chronic Pain

Pre-op Interventions to Mitigate Post-op Acute and Chronic Pain H A R S H A S H A N T H A N N A. M D, M S C A S S O C I A T E P R O F E S S O R D E P A R T M E N T O F A N E S T H E S I A C H R O N I C P A I N P H Y S I C I A N S T J O S E P H ' S H E A L T H C A R E M C M A S T E R U N I V E R S I T Y

Conflict of Interest and Disclosure No potential conflicts of interest exists in relation to this presentation

Conventional Thinking Preoperative Factors Modify pain outcomes after surgery

Acute to Chronic Pain-A Continuum Psychological History of Chronic Pain Patient specific Modality/ Surgery specific Increasing prevalence and patient burden Genetics/Others PREOPERATIVE FACTORS FACTORS AFFECTING DURING SURGERY & TRANSITION FACTORS DURING MAINTENANCE OF CHRONIC PAIN

Central Sensitization Amplification in the Neural Signalling in the CNS = Pain Hypersensitivity PERIPHERAL SENSITIZATION CENTRAL SENSITIZATION Stimuli-nociceptive Pathways With Non-nociceptor Inputs Stimuli-nociception Repeated or Significantly Bad Stimuli Threshold falls, Signals Amplified Mechanoreceptor myelinated fibres- Ab Enhancement In The Functional Status Of Neurons And Circuits PAIN STILL COUPLED Stimulus, Intensity and Duration Long lasting but Not for ever PAIN UNCOUPLED Stimulus, Intensity and Duration Long lasting No protective function Latremoliere A, Woolf CJ. Central sensitization: a generator of pain hypersensitivity by central neural plasticity. Journal of Pain 2009;10:895e926.

Preventing Sensitization ANIMAL MODELS AND HUMAN STUDIES HAVE SHOWN PRE-EMPTIVE DOES NOT WORK Analgesic intervention administered before the surgical incision (nociception) is more effective in relieving acute postoperative pain than the same treatment starting after surgery. It is not the TIMING but both the DURATION and the EFFICACY of the PERIOPERATIVE analgesic intervention that are important in treating postoperative pain and in preventing central sensitization. How to assess: The intervention should reduce postoperative pain behavior beyond the expected duration of the analgesic effect. How to assess: operationally assessed as the analgesic effect of a medication outlasting its clinical duration of action by 5.5 half-lives

What is Persisting Pain After Surgery? 1. Pain present for >3 months. 2. Pain that increased or developed after surgery. 3. The pain is not better explained by an infection, a malignancy, a pre-existing pain condition or any other alternative cause. 4. Localized to the surgical field or area of injury or projected to the innervated territory of a nerve associated Despite the increased attention to PPP, most studies have done little more than codify the striking frequency with which this problem occurs after many disparate types of surgery: from inguinal herniorrhaphy to thoracotomy to breast surgery. Anesthesiology 2010; 112:514 5

Questions? When do we call it persisting and not acute (biologically)? What happens during the phase of translation? Is it a predisposition? Is the relation between acute surgical pain causative or merely associative? Joel Katz & Ze ev Seltzer (2009) Transition from acute to chronic postsurgical pain: risk factors and protective factors, Expert Review of Neurotherapeutics, 9:5, 723-744.

Potential FACTORS

Wu CL, Raja SN. Treatment of acute postoperative pain. Lancet. 2011 Jun 25;377(9784):2215-25.

Preoperative Factors (patient) Hypervigilance Patient expectations Depression Anxiety PATIENT Preoperative pain Endogenous Modulation Poor coping Catastrophizing Opioid induced hyperalgesia Pain in other parts of the body Genetics

The coefficient of determination of the predictive models was less than 54%. QUESTION: Are we looking at the right factors? Do we have the right tools?

1. Capacity overload 2. Preoperative pain in the operating field 3. Other chronic preoperative pain 4. Post-surgical acute pain 5. Co-morbid stress symptoms

2,929 patients scheduled for inguinal hernia repair, hysterectomy (vaginal or abdominal), or thoracotomy Association between CPSP and 90 genetic markers plus a series of clinical factors for a CPSP risk model Surgical type: ++ Genetics-No role Pre-op Pain:+++ Postop Pain:?? CPSP assessed at 4 months 527 patients (18.0%) 13.6% after hernia repair 11.8% after vaginal hysterectomy 25.1% after abdominal hysterectomy 37.6% after thoracotomy

Genetics and Pain Contribution: Largely unclear Possible considerations Genetic predisposition OR insensitivity to pain Genetic effects on analgesics The effect on acute pain vs. chronic pain may be different. Huge variations in phenotypes could explain differences in analgesic effects. So far, no evidence to support its role in CPSP.

Endogenous pain modulation Inhibition Activation Increases pain sensitivity The intensity of suprathreshold heat pain was most consistently shown to correlate with postoperative pain. Genetic vs. Acquired? Do previous pain or other comorbidities affect it? Is it feasible in clinical practice?

Mechanistic Approach Surgery Neural Blockade Preoperative Pain Anxiety PAIN STIMULATION Biological Psychological Social Pain in other parts PAIN SENSITIVITY Catastrophizing Depression OIH PAIN EXPERIENCE Coping

Preoperative Interventions BIOLOGICAL PSYCHOLOGICAL PATIENT SPECIFIC ANALGESIC PATHWAY from preoperative phase to recovery ERAS Multimodal analgesia PROSPECT Perioperative Home

Psychological Interventions CHALLENGES Patient identification-how to flag? Many tools and constructs Resources and logistics Active vs. Inactive SUGGESTED APPROACHES Involve the patient in decision making-improves satisfaction and lessens decisional conflict Educational material provided is more effective than displaying leaflets Involve a pain psychologist or a team approach Patient specific analgesic pathwayinvolve the patient in their decision making

Biological Interventions Regional Blockade Neuraxial techniques Peripheral nerve blockade Local infiltration Systemic Medications Opioids NSAIDS Steroids Adjuvants

Role of Regional Blockade Get LA infiltration where-ever possible Choose and use a regional modality that is effective, safe and practical Regional works for preventive analgesia Its role in preventing PPSP or long term outcomes is still uncertain PNBs are more effective in reducing movement induced pain compared to systemic analgesics. PNBs are much more safer compared to neuraxial techniques. They are of great advantage in trauma patients

Role of Regional Blockade

Regional Blockade and Persistent Pain Small studies with significant limitations

NMDA Antagonists-KETAMINE

Adjuvants-antidepressants Heterogeneity because of differences in drug, dosing regimen, outcomes, and/or surgical procedure precluded any meta-analyses. Superiority to placebo was reported in 8 of 15 trials for early pain reduction and 1 of 3 trials for chronic pain reduction. Insufficient Evidence- Not recommended due to potential adverse effects

Adjuvants-Gabapentinoids Effective? Preoperative vs. Postoperative? One dose? Multiple doses? In patients with preoperative pain? Opioid sparing + Decreased PONV? Significant potential for risks Anesthesiology 2016; 124:10-2

Pharmacotherapy And Persistent Pain

Multimodal analgesiawhat do we include into it? Nonopioids Opioids SAFE AND PRACTICAL Tolerance Safety Patient acceptability Interactions Cost and practical considerations Regional blockade MULTIMODAL ANALGESIA WHAT S THE OUTCOME (evidence) Decreased Opioid use Decreased Pain scores Decreased PONV Longer acting vs. Short acting Prevents persistent pain

Procedure Specific Considerations 32 LA infiltration works nearly as good as nerve blocks for knee arthroplasty, but not for hip arthroplasty!

Perioperative Home

Creating a Seamless System of Team-Based Care Patient Centered Medical Home Perioperative Surgical Home 2016 AMERICAN SOCIETY OF ANESTHESIOLOGISTS. 36

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