Perioperative Pain Management for the Patient with Chronic Pain

Educational Objectives

The goal of this activity is to improve the management of postoperative pain. After hearing and assimilating this lecture, the clinician will be better able to:

1. Implement evidence-based strategies for the management of acute postoperative pain.

2. Formulate a regimen of postoperative pain control for a patient taking opioids preoperatively.

Summary

Acute postoperative pain: uncontrolled severe pain causes increased sympathetic activity, tachycardia, and hypertension; may predispose patients to myocardial infarction or poor wound healing; other manifestations include fear, resistance to movement, insomnia, impaired rehabilitation, and increased risk for prolonged hospitalization and readmission; pain after upper abdominal surgery can cause splinting and predispose to atelectasis and pneumonia

Chronic postsurgical pain (CPP): defined as pain condition resulting from surgery; in most cases, CPP mild and resolves over time; small percentage of patients continue to experience chronic and even severe pain; urologic surgery — 2 articles reported on patients with pain following nephrectomy; 6 mo after nephrectomy, incidence of chronic pain ≤8%; other data demonstrate incidence of chronic pain after radical prostatectomy >1%, and after vasectomy, incidence of chronic testicular pain ≤5%

Risk factors for severe and/or chronic pain after surgery: young age and female sex associated with greater acute pain; preoperative anxiety; catastrophizing (global pessimistic outlook); severe acute postoperative pain correlated with chronic postsurgical pain; patients with chronic pain conditions (eg, fibromyalgia, irritable bowel syndrome, chronic headaches) tend to have higher rates of acute and chronic postsurgical pain; opioids — patients who receive preoperative opioids have more severe chronic postsurgical pain; study of patients undergoing thoracotomy found that, in those receiving no opioids before surgery, incidence of CPP 5%, while in those receiving any opioids before surgery, incidence 45%; surgical and anesthetic factors — general anesthesia eliminates experience and memory of pain but does not block peripheral nervous system; peripheral nervous system activated during surgical incision and sends high threshold nociceptive input to spinal cord; neurons of dorsal horn become hyperexcited (termed “central sensitization”); surgical trauma also causes release of inflammatory cytokines, bradykinins, leukotrienes, and hydrogen ions, which augment transmission of pain signals via peripheral nerves (termed peripheral sensitization); combination of central and peripheral sensitization amplifies pain signals and can prolong postoperative pain; patients with sensitization experience pain in response to low-intensity stimuli that do not normally cause pain (allodynia)

Treatment of postoperative pain: establish realistic goals; patients may mistakenly expect no pain after surgery; identify comorbidities expected to compound difficulty treating pain; surgeries known to cause high levels of pain require more aggressive regimens; elderly patients should be given lower doses; treatment of patients with chronic pain — require higher doses of opioids; underdosing common mistake; do not attempt to wean opioids in postoperative period; recognize non-nociceptive sources of suffering; opioids do not effectively treat depression, anxiety, or neuropathic pain; psychiatrist can offer effective options

Evidence-based treatment: reductions in pain scores and opioid requirements greater with intravenous (IV) patient-controlled analgesia (PCA) than with “as needed” intravenous opioids; multimodal analgesia provides better control of pain and causes fewer adverse effects than opioids; epidural catheters provide better pain control than IV opioids (especially after major surgery); opioid-sparing regimens hasten return of bowel function (particularly after major abdominal surgery); poorly controlled acute pain predisposes patients to chronic pain

Opioids: although goal is to limit use, they remain standard agents for control of postoperative pain; no particular opioid shown to be superior; continuous dosing of morphine should be avoided in patients with renal dysfunction; fentanyl patches and methadone may be continued for patients already receiving them preoperatively but should not be used for postoperative pain (because of long half-life); buprenorphine — opioid agonist-antagonist; has high affinity for mu receptor; high doses block other opioids and limit effectiveness of other agents; meperidine — active metabolites potentially neurotoxic (may cause seizures); may cause tachycardia (similar to atropine); not recommended

Risk factors for opioid-induced respiratory depression: older age (especially >70 yr); basal infusions on PCA pumps (particularly in opioid-naive patients); impairment in renal, hepatic, cardiac, or pulmonary function; sleep apnea; obesity; concomitant use of other depressants (eg, benzodiazepines); sedation induced by opioids; surgery within preceding 24 hr

Preemptive analgesia: administration before exposure to stimulus (ie, surgery) decreases peripheral and central sensitization; improves pain control and reduces opioid requirements

Gabapentinoids: include gabapentin (Neurontin) and pregabalin (Lyrica); both bind to presynaptic voltage-gated calcium channels and decrease release of neurotransmitters in spinal cord; reduce opioid requirements and postoperative pain scores; side effects include sedation, dizziness, slowing of cognition, and ataxia; modest doses for perioperative period usually tolerated well; advantages include no slowing of gastrointestinal motility, no respiratory depression, decrease opioid requirements, and addresses neuropathic component of pain; studies — found preoperative administration of gabapentin to patients undergoing percutaneous nephrolithotripsy associated with less catheter-related bladder discomfort, lower pain scores, and decreased use of opioids; in study of patients undergoing radical retropubic prostatectomy, those who received gabapentin preoperatively had decreased pain scores but did not use less opioid agents; study of 60 patients undergoing radical nephrectomy found reduced pain scores and opioid requirements among those who received gabapentin; most studies gave large doses 1 to 2 hr before induction of anesthesia and smaller doses postoperatively for ≈2 days; gabapentin 600 to 1200 mg and pregabalin 150 to 300 mg given preoperatively in studies

Ketamine: acts on N-methyl-D-aspartate (NMDA) receptors in central nervous system; anesthetic at high doses; has analgesic effects without excessive sedation when given at low doses; side effects more troublesome than gabapentinoids; hallucinations, postoperative delirium, tachycardia, and hypertension can occur at high doses; advantages include low risk for respiratory depression, lower pain scores, decreased opioid requirements, no alteration in gastrointestinal motility, and treatment of neuropathic pain; Cochrane review — found that only half of studies of ketamine reported reduced pain scores postoperatively, but most studies reported lower opioid requirements; ketamine in patients undergoing lumbar spine surgery — study found benefit only in patients on >40 mg of morphine preoperatively; therefore, speaker recommends ketamine only for opioid-tolerant patients

Multimodal analgesia: combines agents with different mechanisms of action; advantages include reduced dosing of all agents, fewer adverse effects of opioids, and improved control of pain; retrospective study — in patients undergoing robot-assisted radical prostatectomy, those given preoperative and postoperative pregabalin, acetominophen, celecoxib (Celebrex) and opioid compared with those who received postoperative regimen of ketorolac and oxycodone-acetaminophen; multimodal regimen associated with decreased intraoperative and postoperative opioid requirements but no change in length of hospital stay

Epidural catheters: associated with lower pain scores after surgery; superior to PCA in patients undergoing abdominal surgery; do not shorten length of stay; shorten time to return of bowel function in patients undergoing major open abdominal surgery, but not for laparoscopic surgery

Acetaminophen: decreases pain scores and opioid requirements when given in large doses on scheduled basis; data from dental literature found 1000 mg significantly better than lower doses; intravenous formulation — compared with oral form, has quicker onset, but no data demonstrate superior analgesia; 300 times more expensive than oral form

Nonsteroidal anti-inflammatory drugs (NSAIDS): decrease pain scores and opioid requirements; reasonable component of multimodal regimen; relatively contraindicated for some surgical patients; selective COX-2 inhibitors (eg, celecoxib) have best profile with regard to gastrointestinal side effects but no advantage for cardiac side effects; nonselective agents (eg, ibuprofen, naproxen) associated with higher incidence of gastrointestinal side effects but may have fewer cardiac side effects

Lidocaine patches: radical prostatectomy study — patients randomized to receive lidocaine patch on either side of incision or placebo patch; patients who received lidocaine reported less pain at rest and with coughing, and improved satisfaction; ≤3 patches can be used simultaneously; may be cut to any shape and placed around multiple incisions

Illustrative case: 56-yr-old woman with past medical history of lumbar spine surgery, chronic low back pain, migraines, and anxiety scheduled for laparoscopic hand-assisted nephrectomy; medications include sustained-release morphine 60 mg 3 times daily, oxycodone 10 mg/acetaminophen 325 mg 6 times daily, and alaprazolam; speaker recommends preoperative administration of pregabalin 225 mg, intraoperative infusion of ketamine at low dose, and postoperative sustained-release morphine 60 mg/8 hr, morphine PCA 3 mg/10 min, scheduled acetaminophen, small dose of pregabalin, and lidocaine patches around incision; after 2 days, start oral opioid as needed

Readings

Cooperberg MR: Active surveillance for low-risk prostate cancer-an evolving international standard of care. JAMA Oncol 2016 Oct 20; Loeb S et al: Active surveillance for prostate cancer: a systematic review of clinicopathologic variables and biomarkers for risk stratification. Eur Urol 2015 Apr;67(4):619-26; McCammack KC et al: Restriction spectrum imaging improves MRI-based prostate cancer detection. Abdom Radiol (NY) 2016 May;41(5):946-53; Newcomb LF et al: Canary Prostate Active Surveillance Study (PASS); Design of a multi-institutional active surveillance cohort and biorepository. Urology 2010 Feb;75(2):407-13; Ross AE et al: Prostate-specific antigen kinetics during follow-up are an unreliable trigger for intervention in a prostate cancer surveillance program. J Clin Oncol 2010 Jun 10;28(17):2810-6; Wilt TJ et al: Radical prostatectomy versus observation for localized prostate cancer. N Engl J Med 2012 Jul 19; 367(3): 203-213.

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, members of the faculty and planning committee reported nothing to disclose. In his lecture, Dr. Furnish presents information related to off-label or investigational use of a therapy, product, or device.

Acknowledgements

Dr. Furnish was recorded at the 9th Annual Urology Postgraduate Course: Clinical Case Discussions in Urology, presented by the University of California, San Diego, School of Medicine, Department of Urology, and the Moores Cancer Center at University of California, San Diego, and held March 11-12, 2016, in San Diego, CA. For information on upcoming events from the UCSD School of Medicine, please visit cme.ucsd.edu. The Audio Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

UR401502

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.