Can Chronic Pain Be Prevented?

Use of cardiopulmonary bypass is associated with chronic postsurgical pain among patients undergoing coronary artery bypass graft surgery: follow-up of a randomized, clinical trial

BACKGROUND

Chronic postsurgical pain (CPSP) worsens patients' mortality, morbidity, and quality of life. Cardiopulmonary bypass is mandatory for cardiac surgery, but it induces intense inflammation. The presence of inflammation is a crucial part of pain sensitization. An extreme inflammatory response due to cardiopulmonary bypass might cause a high prevalence of CPSP after cardiac surgery. We hypothesized that the prevalence and severity of CPSP are higher in patients after on-pump coronary artery bypass graft (CABG) surgery than in those after off-pump CABG surgery.

METHODS

This prospective, observational study was performed on a cohort from a randomized trial (on-pump CABG: 81 patients, off-pump CABG: 86 patients). A questionnaire about the severity of surgical wound pain that evaluated pain with the numerical rating scale (NRS) was filled out by the patients. NRS responses for current pain, peak pain in the last 4 weeks, and average pain in the last 4 weeks were evaluated. The main outcomes were the severity of CPSP as evaluated using the NRS and the prevalence of CPSP. CPSP was defined as pain with an NRS score > 0. Differences in severity between groups were analyzed using multivariate ordinal logistic regression models adjusted for age and sex, and differences in prevalence between groups were analyzed using multivariate logistic regression models adjusted for age and sex.

RESULTS

The questionnaire return rate was 77.0%. During a median follow-up of 17 years, 26 patients complained of CPSP (on-pump CABG: 20 patients, off-pump CABG: 6 patients). Ordinal logistic regression showed that the NRS response for current pain (odds ratio [OR] 2.34; 95% CI 1.12-4.92; P = 0.024) and the NRS response for peak pain in the last 4 weeks (OR 2.71; 95% CI 1.35-5.42; P = 0.005) were significantly higher in patients who underwent on-pump CABG surgery than in those who underwent off-pump CABG. Logistic regression showed that on-pump CABG surgery was an independent predictor of CPSP (OR 2.59; 95% CI 1.06-6.31; P = 0.036).

CONCLUSIONS

The prevalence and severity of CPSP are higher in patients with on-pump CABG surgery than in those with off-pump CABG surgery.

"Persistent Post-Operative Pain in Children - An Argument for a Transitional Pain Service in Pediatrics"

BACKGROUND

Persistent post-operative pain continues to occur in pediatric patients. Despite the growing amount of literature on causes, there is little discussion on treatment and prevention with a majority of studies focusing on specific surgeries.

AIM

The aim of this retrospective chart study is to identify risk factors and clinical features of persistent post-operative pain after any surgery in a pediatric quaternary complex pain service, describe the pharmacologic and non-pharmacologic management in children, and explore options to improve outcomes, in particular, the introduction of a transitional pain service.

METHODS

A retrospective chart review recorded demographics, gender, age, pain location and surgery type, treatment, and outcomes of 31 children identified through relevant registers over a 2-year period.

RESULTS

A total of 31 children were positively identified as having persistent post-operative pain and were seen in the complex pain clinic. Consistent with the literature, most cases represented neuropathic pain and persistent post-operative pain was most commonly seen after orthopedic surgery. All but four children had resolution of their pain after implementing the pain management plan. Management was characterized by early intervention, emphasis on non-pharmacologic strategies, and conservative use of opioids.

CONCLUSIONS

Identifying risk factors is useful, however putting strategies into place for prevention is necessary. Early intervention and the implementation of strategies before and immediately after are best provided by a transitional pain service.

Dealing with Chronic Pain: Tips to Teach Undergraduate Health Sciences Students

Chronic pain is a significant and costly problem all over the world that negatively impacts the quality of life of sufferers. There are clear discrepancies between the prevalence of chronic pain in society and the low priority assigned to educating future physicians about the complexities of pain. This condition also occurs in other undergraduate health science students, although research in this area has not been studied as much as in medical schools. Based on the International Association for the Study of Pain (IASP) Pain Curriculum Outline, a systematic search of the available literature, and the authors' own experiences, we highlight some relevant tips to educate health science trainees in the management of patients with chronic pain. These tips highlight current international recommendations for a comprehensive approach to this prevalent problem in society, which should be learnt during the university training of health professionals.

Pain "chronification": what is the problem with this model?

OBJECTIVES

There appears to be an unwarranted focus on all chronic pain being a "chronification" of acute pain. Despite a plethora of studies on mechanisms to prevent this "chronification" following surgery, the positive effects have been minimal. An alternate model to explain chronic pain is presented.

METHODS

Research in PUBMED and accessing data from the HUNTpain examination study.

RESULTS

Data from the HUNT pain examination study reveal that less than 25% of individuals with chronic pain in a general population can relate the onset to an acute event. Another theory explaining the origin of chronic pain is that of priming and the accumulation of events that can be predictors along a continuum before chronic pain is apparent. This theory is presented to refocus for better prevention and treatment of chronic pain.

CONCLUSIONS

"Chronification" cannot explain all cases of chronic/persistent pain. The plastic changes in the pain processing system can be seen as a continuum where at some point where an acute pain event is only one of several possible tipping points on this continuum that changes potential pain to perceived pain.

Wound Infusion of 0.35% Levobupivacaine Reduces Mechanical Secondary Hyperalgesia and Opioid Consumption After Cesarean Delivery. A Prospective, Randomized, Triple-Blind, Placebo-Controlled Trial

BACKGROUND

Some patients still report moderate-to-severe postoperative pain after cesarean delivery. Local anesthetic wound infusion improves acute pain and might act on peripheral and central sensitization mechanisms; however, no studies have proved this hypothesis. We evaluated the potential benefits of continuous wound infusion of levobupivacaine after cesarean delivery on secondary hyperalgesia (primary end point) and primary hyperalgesia, pain relief, persistent pain, and inflammatory and metabolic stress response.

METHODS

Healthy women scheduled for elective cesarean delivery participated in this prospective, randomized, triple-blind, placebo-controlled trial (NCT01458431). All patients received spinal anesthesia with 0.5% hyperbaric bupivacaine with fentanyl and a multiholed wound catheter placed under the fascia. Women were randomized to receive continuous wound infusion (0.35% levobupivacaine 7 mL/h for 48 hours; group L) or an equal volume of saline (group S). Secondary hyperalgesia to punctate mechanical stimuli was evaluated using dynamic tests, and primary hyperalgesia was evaluated using an electronic von Frey anesthesiometer; both were assessed at 24, 48, and 72 hours. The following variables were collected: intensity of postoperative parietal and visceral pain at rest and on movement rated on a visual analog scale >72 hours, time to first bolus of patient-controlled analgesia (PCA), cumulative dose of rescue morphine (PCA) and acetaminophen, ability to sleep and sleep quality, and patient satisfaction. Persistent postoperative pain was evaluated during a telephone interview at 1, 3, 6, and 12 months after surgery. C-reactive protein, acid glycoprotein, preprandial glucose, insulin, cortisol, prolactin, growth hormone, and interleukin-6 were measured before cesarean delivery and at 8, 24, and 48 hours. Adverse events and patient outcomes were recorded.

RESULTS

Seventy women were included. In group L, the area of secondary hyperalgesia was significantly reduced (43.4 [18.5-80] vs 68.4 [39.0-136] cm2 and 45.1 [0.9-89.8] vs 67.3 [31.3-175] cm2 at 24 and 48 hours, respectively; group:time interaction P value < .001), the mechanical pain threshold was significantly higher at 24 hours (633 [441-802] vs 417 [300-572] g.mm-2; P = .001), and morphine consumption was significantly lower at 24 hours (4 [2-11] vs 11[6-23]; P = .003) compared with group S. Levobupivacaine had no effect on persistent postoperative pain at 1, 3, 6, and 12 months. Plasma insulin levels in the immediate postoperative period and at 8, 24, and 48 hours were significantly lower in group L (P < .001). There were no significant differences in other biochemical parameters of inflammatory and endocrine-metabolic response.

CONCLUSIONS

Levobupivacaine wound infusion provides adequate analgesia and might be an effective antihyperalgesic adjunct.

Incidence of chronic pain 6 y after major trauma

BACKGROUND

Life saving measures is the main focus in the initial treatment of major trauma. In surviving patients, chronic pain may be a serious problem, but the long term incidence and potential risk factors are not very well studied.

METHODS

All adult trauma patients included in the institutional trauma registry in 2007 were assessed for eligibility. Among exclusion criteria were: Injury Severity Score < 9, endotracheal intubation before or during admission, spinal cord lesion, known chronic drug or substance abuse, major surgery within 3 h after admission. A patient questionnaire was sent out 6 y after injury focusing on frequency and intensity of pain. A subgroup analysis was done in patients with thoracic injuries, comparing patients with epidural analgesia (EDA) and patients without.

RESULTS

Sixty-eight patients were included in the study. Sixty-nine percent reported pain 6 y after injury and 24% had severe pain. The severity of the injury was a risk factor for development of chronic pain, whereas pain during initial hospital stay was not. In patients with thoracic injuries there was no correlation between initial treatment with EDA and decreased incidence of chronic pain, however patient numbers were small. Opioids were the main analgesics used initially; no patients received non-steroidal anti-inflammatory drugs or peripheral nerve blocks during the first 24 h.

CONCLUSION

Two thirds of the trauma patients had chronic pain 6 y after injury and one out of four had severe pain. The initial pain treatment was focused on opioids.

Persistent Post-Mastectomy Pain: Risk Factors and Current Approaches to Treatment

Persistent Post-Mastectomy Pain (PPMP) is a common condition that can follow surgeries for breast cancer, the most common cancer in women. Because of the frequency of PPMP and its potential severity, it has received increasing research attention. This manuscript reviews the recent research literature, beginning with a brief history and then relevant medical, surgical, demographic, and psychosocial risk factors. Subsequently, social, psychological, and functional sequelae that have been linked to PPMPS are considered, as is research on current pharmacological, psychological, and rehabilitative approaches to treatment. The review concludes with a discussion of directions for future research and treatment that might reduce the incidence and impact of PPMP on breast cancer survivors. PERSPECTIVE: This article describes current research literature involving mechanisms, risks, and treatments related to persistent post-mastectomy pain. Implications of research findings also are discussed for pre- and post-surgical approaches to pain management, current treatments, and promising research directions.

Poorly controlled postoperative pain: prevalence, consequences, and prevention

This review provides an overview of the clinical issue of poorly controlled postoperative pain and therapeutic approaches that may help to address this common unresolved health-care challenge. Postoperative pain is not adequately managed in greater than 80% of patients in the US, although rates vary depending on such factors as type of surgery performed, analgesic/anesthetic intervention used, and time elapsed after surgery. Poorly controlled acute postoperative pain is associated with increased morbidity, functional and quality-of-life impairment, delayed recovery time, prolonged duration of opioid use, and higher health-care costs. In addition, the presence and intensity of acute pain during or after surgery is predictive of the development of chronic pain. More effective analgesic/anesthetic measures in the perioperative period are needed to prevent the progression to persistent pain. Although clinical findings are inconsistent, some studies of local anesthetics and nonopioid analgesics have suggested potential benefits as preventive interventions. Conventional opioids remain the standard of care for the management of acute postoperative pain; however, the risk of opioid-related adverse events can limit optimal dosing for analgesia, leading to poorly controlled acute postoperative pain. Several new opioids have been developed that modulate μ-receptor activity by selectively engaging intracellular pathways associated with analgesia and not those associated with adverse events, creating a wider therapeutic window than unselective conventional opioids. In clinical studies, oliceridine (TRV130), a novel μ-receptor G-protein pathway-selective modulator, produced rapid postoperative analgesia with reduced prevalence of adverse events versus morphine.