New concepts in acute pain management: strategies to prevent chronic postsurgical pain, opioid-induced hyperalgesia, and outcome measures

How to Modulate Peripheral and Central Nervous System to Treat Acute Postoperative Pain and Prevent Pain Persistence

Chronic postoperative pain (CPSP) is a major issue after surgery, which may impact on patient's quality of life. Traditionally, CPSP is believed to rely on maladaptive hyperalgesia and risk factors have been identified that predispose to CPSP, including acute postoperative pain. Despite new models of prediction are emerging, acute pain is still a modifiable factor that can be challenged with perioperative analgesic strategies. In this review we present the issue of CPSP, focusing on molecular mechanism underlying the development of acute and chronic hyperalgesia. Also, we focus on how perioperative strategies can impact directly or indirectly (by reducing postoperative pain intensity) on the development of CPSP.

The association of hemodynamic parameters and clinical demographic variables with acute postoperative pain in female oncological breast surgery patients: A retrospective cohort study

OBJECTIVES

Appropriate administration of intraoperative analgesia is an essential factor in care and reasonable recovery times. Inappropriate intraoperative analgesia puts the patient at risk of acute postoperative pain (APOP). The absence of an objective standard for intraoperative nociceptive monitoring complicates pain care. Heart rate (HR) and mean arterial blood pressure (MABP) have been suggested as useful parameters during general anesthesia for nociceptive monitoring. However, studies focusing on whether intraoperative heart rate variability (HRv) and mean arterial blood pressure variability (MABPv) during general anesthesia can accurately monitor nociception in patients have remained inconclusive. The current study aimed to (1) identify the association of intraoperative heart rate and blood pressure variability in patients undergoing low-risk surgery with the incidence of APOP in the immediate postoperative setting and (2) evaluate the associations of clinical demographic factors with the incidence of APOP.

METHODS

A retrospective observational cohort study was conducted. The outcome was moderate-to-severe APOP, defined as a numeric rating scale score of ≥ 4. HRv, MABPv, and potential confounders, such as age, body mass index, duration of surgery, smoking, depression, preoperative use of analgesics, and type of surgery, were used as independent variables.

RESULTS

Data from 764 female oncological breast surgery patients were analyzed. No statistically significant association of HRv and MABPv with APOP was found. Lower age was associated with higher odds of APOP (odds ratio [OR] 0.978, p = 0.001). Increased length of surgery (OR 1.013, p = 0.022) and a history of depression were associated with increased odds of APOP (OR 2.327, p = 0.010). The subtype of surgery was statistically significantly associated with APOP (p = 0.006).

CONCLUSIONS

Our results suggest that heart rate and blood pressure variability intraoperatively, in female patients undergoing low-risk surgery, are not associated with, and thus not predictive of, APOP in the immediate postoperative setting.

Analgesic Effect of Esketamine Combined with Tramadol for Patient-Controlled Intravenous Analgesia After Cesarean Section: A Randomized Controlled Trial

Purpose

High rate of cesarean section (CS) bring challenges to analgesic management after CS. Previous studies state that adjuvant treatment with a low dose of esketamine intraoperatively could reduce postoperative pain and opioid consumption, and even prevent postpartum depression. However, few researches involve in patient-controlled intravenous analgesia (PCIA) with esketamine after CS. In this trial, we explored a new combination of esketamine with tramadol for PCIA after CS with the aim to provide a better analgesic regimen for use in the clinic.

Patients and Methods

170 puerperae undergoing CS were recruited for this trial and randomly assigned into 2 groups (1:1): The control group received a formula of PCIA with butorphanol 0.1mg/kg and tramadol 400mg postoperatively, while the intervention group received a formula of PCIA with esketamine 1mg/kg and tramadol 400mg. The primary outcome was the mean numerical rating scale (NRS) scores at rest, sitting, and uterine contraction at 6 hours postoperatively. The second outcomes included the mean NRS scores at rest, sitting, and uterine contraction at 12, 24, and 48 hours postoperatively. The incidence of adverse events, postoperative sedation, postoperative sleep quality, maternal satisfaction regarding postoperative analgesia and the Edinburgh postnatal depression scale (EPDS) score were also be evaluated.

Results

The mean (SD) of the mean NRS scores at rest, sitting, and during uterine contraction at 6 hours postoperatively were 4.8 (0.7) points in the intervention group and 5.3 (0.5) points in the control group. The estimated mean difference between the two groups at 6 hours postoperatively was -0.5 points (95% confidence interval [CI], -0.7 to -0.3; P < 0.001). Compared with the control group, the patients in the intervention group had a significantly lower mean pain intensity at 12 and 24 hours postoperatively (-0.5 points [95% CI, -0.6 to -0.3]; P < 0.001 and -0.2 points [95% CI, -0.4 to 0]; P = 0.019 respectively). Otherwise, differences at 48 hours after surgery between the two groups were nonsignificant (0 points [95% CI, -0.2 to 0.2]; P = 0.802). The incidence of adverse events in the intervention group (11.8%) was significantly lower than in the control group (24.7%) (ratio difference -12.9, [95% CI, -24.3 to -1.5]; P = 0.029). No difference was found in postoperative sleep quality (P = 0.765), analgesic satisfaction (P= 0.818) and EPDS scores (P = 0.154) between the two groups.

Conclusion

In this trial, among patients undergoing CS, esketamine combined with tramadol by PCIA improved pain intensity 6 hours postoperatively compared with butorphanol combined with tramadol.

Prolonged continuous wound infusion of local anesthetic and steroid after major abdominal surgery to reduce opioid consumption: a randomized, double-blind trial

BACKGROUND

Continuous wound infusion (CWI) is effective for post-operative pain management, but the effect of prolonged infusions and the use of steroids in the infused mixture have never been addressed. We investigate the effect of prolonged CWI with ropivacaine 0.2% (R) over seven days and methylprednisolone (Mp) 1 mg/kg infused in the wound in the first 24 hours.

METHODS

This is a randomized, double blind, phase III trial (RCT) in major abdominal surgery with laparotomy. After a 24-hours pre-peritoneal CWI of R-Mp, patients were randomized to receive either R-Mp or placebo for the next 24 hours. Then, patient-controlled CWI with only ropivacaine 0.2% or placebo (according to the randomization group) was planned between 48 hours and seven days after surgery. Morphine equivalents at seven days were analyzed, together with any catheter- or drug-related side effect and PPSP at 3 months.

RESULTS

We enrolled 120 patients (63 in the CWI group, 57 in the placebo group). Prolonged CWI did not reduce opioid consumption in the first seven postoperative days (P=0.08). CWI was associated with reduced consumption of non-opioid analgesics (P=0.03). Most of the patients continued to require bolus in the surgical wound beyond 48 hours. PPSP prevalence was not different between groups.

CONCLUSIONS

Prolonged infusion with R-Mp is safe and effective but did not reduce opioid consumption in the seven days after surgery or PPSP prevalence.

Cross-sectional E-survey on the Incidence of Pre- and Postoperative Chronic Pain in Bariatric Surgery

BACKGROUND

To assess the prevalence, incidence, location, and behavior of chronic pre- and postoperative pain in bariatric surgery, and the use of analgesics.

METHODS

A cross-sectional e-survey was conducted on 3928 post-bariatric patients and four-time points for pain assessment were evaluated: preoperative, on the ward, day 1 at home postoperatively, and present time (at the time of the e-survey). A numerical rating scale (NRS) was used to assess the level of pain (0 to 10). The general incidence of chronic pain was calculated, as also, subgroups were defined as group A (pre and postoperative chronic pain), B (preoperative pain, and no longer postoperative), and C (preoperative painless, postoperative chronic pain). Besides the pain intensity, location of pain, and the use of analgesics were investigated.

RESULTS

A total of 3279 patients (83.9%) responded to the survey. Preoperative and postoperative chronic pain was found in 343 (10.5%) and 264 (8.1%) patients, respectively. In group A, chronic pain was present in 4.8% of the patients; in group B, it was present in 5.7%; and in group C in 3.3% of the patients. Furthermore, in 4.5% of patients pain was located in the abdomen, which was higher as compared to before surgery (+ 2.3%, p < 0.001). The ORs for present postoperative chronic pain were OR 1.45, 1.7, and 1.71 (p = 0.002, 0.003, 0.003) compared to respectively preoperative chronic pain, pain at the ward, and pain at day 1 after surgery. Among all participants, 4.6% consumed chronic analgesics. Of these, paracetamol was used most frequently (3.8%), followed by tramadol (1.3%) and oxycodone (0.5%).

CONCLUSIONS

In this e-survey, chronic postoperative abdominal pain was prominent in patients after bariatric surgery. Of patients, 3.3% that were without preoperative chronic pain developed chronic pain after surgery. Opioid consumption in the queried population was relatively low.

Polysaccharide extract of Caesalpinia ferrea (Mart) pods attenuates inflammation and enhances the proliferative phase of rat cutaneous wounds

Pods of Caesalpinia ferrea, popularly used to treat inflammatory processes, were collected to obtain the polysaccharide-rich extract, presenting anti-inflammatory and antinociceptive effects in acute inflammation models. This study aimed to evaluate the anti-inflammatory, antinociceptive and healing activities of the polysaccharide-rich extract from Caesalpinia ferrea pods (PEp-Cf) in the rat model of cutaneous excisional wound. PEp-Cf (0.025-0.1%) or 0.9% NaCl was topically applied in the wounds at dorsal thoracic region (2×/day) during 21 days for measurement of clinical signs (hyperemia, inflammatory exudate, edema, nociception), wound size, histopathological/histomorphometric, oxidative/inflammatory markers and systemic toxicity. PEp-Cf at 0.1% reduced wound area and increased ulcer contraction [days 2 and 10 (21-78%)]. PEp-Cf reduced clinical signs [days 2 and 5 (2.2-2.8×)] and modulated the healing inflammatory phase via stimulation of epithelialization (days 10 and 14), and inhibition of polymorphonuclears [days 2 and 5 (71-74%)], protein leakage [days 2 and 5 (28-41%)], nitrate [days 2 and 5 (2.2-6×)] and malondialdehyde [days 2 and 5 (46-49%)]. PEp-Cf increased the number of blood vessels [days 5 and 7 (3.1-9.6×)], fibroblasts [days 5 and 7 (2.1-6.4×)] and collagen [days 5 to 14 (1.5-1.8×)]. In conclusion, the topical application of PEp-Cf at 0.1% accelerates the healing process of rat cutaneous wounds via modulation of the inflammatory and proliferative phases, being devoid of systemic alterations.

Kinematic Analyses Using Finger-Tapping Task for Patients After Surgery With Distal Radius Fracture at Acute Phase

BACKGROUND

After a distal radius fracture (DRF), severe pain, disabilities, and pain-related psychological problems can arise and sometimes remain ~1 year later. DRF-related disabilities have been assessed with questionnaires but not by kinematic evaluations; the kinematic features of DRF patients are unknown. Here, we investigated the kinematic characteristics of DRF patients and explored the relationship between their clinical assessments and kinematic characteristics.

METHODS

We analyzed 20 patients with DRFs after their surgeries. We recorded their finger-tapping using a magnetic sensor, and we calculated the velocity, magnitude, and movement-initiation hesitation. The patients' pain intensity and fear of movement were assessed by a visual analogue scale and the Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH). To investigate the features of the patients who achieved only slight improvement, we compared the kinematic characteristics of the DRF patients in 2 subgroups: the "good improvement group" and the "slight improvement group" based on a cutoff value of the DASH score (>40) at 1 month postsurgery.

RESULTS

The DASH score at 30 days postsurgery was significantly correlated with hesitation at 1 day postsurgery (r = .66, P < .0071) and with velocity at 7 days (r = -.54, P < .0071). Our kinematic analyses revealed significant differences in velocity at 7 days postsurgery (P < .05) and in hesitation at 1 day postsurgery (P < .05) between the subgroups.

CONCLUSIONS

Since assessments using range-of-motion measurements or a questionnaire are not sufficient to evaluate a patient's movement disorder, a kinematic analysis should be conducted for quantitative assessments.

Prevalence and Predictors of Chronic Pain with Two-Year Follow-Up After Knee Arthroplasty

Background

Pain relief is the most important issue in the long-term outcome of arthroplasty surgery, with nearly one-third of patients still suffered persistent pain and caused dissatisfaction after the surgery.

Methods

A total of 713 patients underwent primary elective primary TKA and UKA were included consecutively between July 2018 and December 2019, using binary logistic method to analyze the data.

Results

The prevalence of CPSP at rest and on movement at 2-year was 12.1% and 37.7% respectively after primary knee arthroplasty and CPSP at rest factors included: age above 80 (odds ratio [OR]= 6.72, 95% confidence interval [CI] 1.58 to 28.56), BMI above 30 (2.339, 1.02 to 5.383), and moderate to severe pain variables: preoperative pain, (1.95, 1.11 to 3.41); APSP on movement, 4.9 (2.31–10.6); and follow-up contralateral knee pain-at-rest scores (12.6, 5.5 to 28.5). Factors associated with presence of CPSP on movement included: no smoking (2.59, 1.07 to 6.26); and moderate to severe pain variables: preoperative pain, (1.57, 1.073 to 2.30); APSP at rest, (1.85, 1.13 to 3.02); APSP on movement, 6.11 (3.82 to 9.78); and follow-up contralateral knee pain-on-movement scores, 3.22 (2.08 to 5.00). Factors to occurrence of moderate to severe CPSP on movement include: presence of COPD (12.20, 2.19 to 67.98); and moderate to severe pain variables: preoperative pain (2.36, 1.32 to 4.23); APSP on movement (4.68, 1.95 to 11.25); and follow-up contralateral knee pain-on-movement scores (2.71, 1.66 to 4.42).

Conclusion

Prevention strategies should be targeted to different types of pain, and the comorbidity of COPD undergoing knee arthroplasty should receive early identification and attention.

Avoid Postoperative Pain To Prevent Its Chronification: A Narrative Review

Acute postoperative pain is a normal and expected part of the patient’s postsurgical trajectory, and its intensity, severity, and duration vary with surgery-related and patient factors. In a subset of patients, postoperative pain does not resolve as the tissue heals but instead transitions to chronic postoperative pain, a challenging condition to treat and one associated with decreased quality of life, sleep and mood disorders, and neuropathy. Promptly and adequately treating acute postoperative pain can reduce the risk that it will transition into chronic postoperative pain. Numerous agents are available that may help treat postoperative pain, including nonsteroidal anti-inflammatory drugs, opioids, antidepressants, anticonvulsants, and others. In this connection, it is also important to consider patient factors, such as mental health status and comorbidities, as well as the type and duration of surgery. A multimodal approach is recommended, which uses two or more agents with complementary mechanisms of action, working at different targets. Multimodal analgesia may also reduce adverse events and lessen opioid consumption after surgery. A particularly useful fixed-dose combination product is dexketoprofen/tramadol (DEX-TRA), which is safe and effective in numerous clinical trials. This review is based on a presentation from the Roma Pain Days scientific sessions of 2021.

Effect of Single Preoperative Dose of Duloxetine on Postoperative Analgesia in Patients Undergoing Total Abdominal Hysterectomy under Spinal Anesthesia

Background:

Women undergoing hysterectomy present a unique set of challenges to the anesthesiologist in terms of postoperative pain management. This study was conducted to see the effect of single-dose perioperative duloxetine 60 mg on postoperative analgesia following abdominal hysterectomy under spinal anesthesia.

Materials and Methods:

This prospective randomized placebo-controlled study was conducted on 64 patients scheduled to undergo elective abdominal hysterectomy under spinal anesthesia. The patients were divided into two groups of 32 in each, Group D received duloxetine 60 mg 2 h preoperatively and Group P received placebo 2 h preoperatively. Postoperatively, the patients were evaluated by an independent observer for pain on rest and during cough at 0 (arrival at postanesthesia care unit), 2, 4, 6, 12, and 24 h. In addition, the postoperative analgesic requirements and adverse effects were noted.

Statistical Analysis Used:

Independent t-test/Mann–Whitney U-test was used to compare the pain score between two groups.

Results:

The demographic data were comparable between both the groups. The mean Visual Analogue Scale scores assessed postoperatively at rest and during cough which were not statistically significant between the two groups. The rescue analgesic consumption in Group D (0.97 ± 0.86) and Group P (1.25 ± 0.76) was comparable and statistically not significant. The total analgesic requirement between duloxetine (4.94 ± 0.84) and placebo (1.25 ± 0.76) group was comparable and statistically not significant. The incidence of nausea vomiting and somnolence was higher in Group D.

Conclusion:

We conclude that patients receiving a single dose of 60 mg duloxetine as premedication before hysterectomy under spinal anesthesia are no better than placebo on postoperative pain during the first 24 h.

Dexmedetomidine combined with sufentanil and dezocine-based patient-controlled intravenous analgesia increases female patients' global satisfaction degree after thoracoscopic surgery

Background

There are no studies on the use of dexmedetomidine combined with sufentanil and dezocine-based patient-controlled intravenous analgesia (PCIA) in females undergoing thoracic surgery. We postulate that introducing dexmedetomidine to a combination of dezocine-based PCA drugs and sufentanil will increase female patients’ global satisfaction degree.

Methods

One hundred fifty-two female patients with physical classification type I or II according to the American Society of Anesthesiologists undergoing thoracoscopic surgery were arbitrarily classified into two categories, either receiving sufentanil and dezocine-based PCIA (group C) or incorporating dexmedetomidine with sufentanil and dezocine-based PCIA (group D). The patients’ global satisfaction degree, postoperative nausea and vomiting (PONV), PCA bolus, rescue analgesia requirements, drug-related adverse effects, rest and coughing visual analogue scale (VAS) ratings, and Ramsay sedation scores (RSS) were measured at 6, 12, 24, 36 and 48 h after surgery.

Results

Compared with the C group, the patient satisfaction degree was significantly higher; pain scores at rest and coughing were significantly different at 6, 12, 24, 36 and 48 h postoperatively; less rescue analgesia and PCA bolus were required; and a lower incidence of PONV was found in the D group. There were non-significant trends for the sedation scores and drug-related adverse effects in both groups.

Conclusions

Dexmedetomidine combined with sufentanil and dezocine increased female patients’ global satisfaction degree after thoracoscopic surgery. This effect could be linked to the improvement in postoperative analgesia and reduction in postoperative nausea and vomiting; the combined treatment did not increase drug-related adverse effects in female patients.

Trial registration

Chinese Clinical Trial Registry number, ChiCTR2000030429. Registered on March 1, 2020.

Frailty status as a potential factor in increased postoperative opioid use in older adults

BACKGROUND

Prescription opioids are commonly used for postoperative pain relief in older adults, but have the potential for misuse. Both opioid side effects and uncontrolled pain have detrimental impacts. Frailty syndrome (reduced reserve in response to stressors), pain, and chronic opioid consumption are all complex phenomena that impair function, nutrition, psychologic well-being, and increase mortality, but links among these conditions in the acute postoperative setting have not been described. This study seeks to understand the relationship between frailty and patterns of postoperative opioid consumption in older adults.

METHODS

Patients ≥ 65 years undergoing elective surgery with a planned hospital stay of at least one postoperative day were recruited for this cohort study at pre-anesthesia clinic visits. Preoperatively, frailty was assessed by Edmonton Frailty and Clinical Frailty Scales, pain was assessed by Visual Analog and Pain Catastrophizing Scales, and opioid consumption was recorded. On the day of surgery and subsequent hospitalization days, average pain ratings and total opioid consumption were recorded daily. Seven days after hospital discharge, patients were interviewed using uniform questionnaires to measure opioid prescription use and pain rating.

RESULTS

One hundred seventeen patients (age 73.0 (IQR 67.0, 77.0), 64 % male), were evaluated preoperatively and 90 completed one-week post discharge follow-up. Preoperatively, patients with frailty were more likely than patients without frailty to use opioids (46.2 % vs. 20.9 %, p = 0.01). Doses of opioids prescribed at hospital discharge and the prescribed morphine milligram equivalents (MME) at discharge did not differ between groups. Seven days after discharge, the cumulative MME used were similar between cohorts. However, patients with frailty used a larger fraction of opioids prescribed to them (96.7 % (31.3, 100.0) vs. 25.0 % (0.0, 83.3), p = 0.007) and were more likely (OR 3.7, 95 % CI 1.13-12.13) to use 50 % and greater of opioids prescribed to them. Patients with frailty had higher pain scores before surgery and seven days after discharge compared to patients without frailty.

CONCLUSIONS

Patterns of postoperative opioid use after discharge were different between patients with and without frailty. Patients with frailty tended to use almost all the opioids prescribed while patients without frailty tended to use almost none of the opioids prescribed.

Opioid free anesthesia: evidence for short and long-term outcome

The introduction of synthetic opioids in clinical practice played a major role in the history of anesthesiology. For years, anesthesiologists have been thinking that opioids are needed for intraoperative anesthesia. However, we now know that opioids (especially synthetic short-acting molecules) are definitely not ideal analgesics and may even be counterproductive, increasing postoperative pain. As well, opioids have revealed important drawbacks associated to poor perioperative outcomes. As a matter of fact, efforts in postoperative pain management in the last 30 years were driven by the idea of reducing/eliminating opioids from the postoperative period. However, a modern concept of anesthesia should eliminate opioids already intra-operatively towards a balanced, opioid-free approach (opioid-free anesthesia - OFA). In OFA drugs and techniques historically proven for their efficacy are combined in rational and defined protocols. They include ketamine, alpha-2 agonists, lidocaine, magnesium, anti-inflammatory drugs and regional anesthesia. Promising results have been obtained on perioperative outcome. For sure, analgesia is not reduced with OFA, but it is effective and with less opioid-related side effects. These benefits may be of particular importance in some high-risk patients, like OSAS, obese and chronic opioid-users/abusers. OFA may also increase patient-reported outcomes; despite it is difficult to specifically rule out the effect of intraoperative opioids. Finally, few data are available on long-term outcomes (persistent pain and opioid abuse, cancer outcome). New studies and data are required to elaborate the optimal approach for each patient/surgery, but interest and publication are increasing and may open the road to the wider adoption of OFA.

Effects of transversus abdominis plane block versus quadratus lumborum block on postoperative analgesia: a meta-analysis of randomized controlled trials

Background

Trunk block technique has been used in postoperative analgesia for patients undergoing surgery, specifically, transversus abdominis plane block (TAPB) and quadratus lumborum block (QLB) have been proved effective. The purpose of this meta-analysis is to evaluate the effects of TAPB and QLB in postoperative analgesia.

Methods

Online databases, including MEDLINE, EMBASE, Cochrane Library (&Trail), Web of Science, CNKI, Wanfang and QVIP were applied to collect the randomized controlled trials (RCTs) from inception to Dec. 9th, 2019. Twenty-two studies were finally included containing 777 patients in the TAPB group and 783 cases in QLB group. RCTs comparing TAPB and QLB in postoperative analgesia were included in this meta-analysis. The indicators including total analgesia consumption postoperatively, operative time, duration of anesthesia, visual analogue scale (VAS) score at 24 h postoperatively, duration of postoperative analgesia, the number of patients requiring analgesia postoperatively and adverse reactions were analyzed.

Results

our findings showed that morphine consumption (mg) (WMD = 3.893, 95%CI: 2.053 to 5.733, P < 0.001), fentanyl consumption (μg) (WMD = 23.815, 95%CI: 15.521 to 32.109, P < 0.001), VAS score at 24 h postoperatively (WMD = 0.459, 95%CI: 0.118 to 0.801, P = 0.008), the number of patients requiring analgesia postoperatively (WMD = 3.893, 95%CI: 2.053 to 5.733, P < 0.001), and the incidence of dizziness (WMD = 2.691, 95%CI: 1.653 to 4.382, P < 0.001) in TAPB group were higher than in QLB group.

Conclusions

QLB is superior to TAPB in reducing morphine consumption, fentanyl consumption, VAS score at 24 h postoperatively, the number of patients requiring analgesia postoperatively, and the incidence of dizziness.

Development of More Precise Measurement to Predict Pain 1 Month Postoperatively Based on Use of Acute Postoperative Pain Score in Patients With Distal Radial Fracture

BACKGROUND

A method for modeling the acute pain trajectory using the simple linear fit of an individual's pain intensity scores after surgery was developed and affords more precise measurement than conventional pain assessment. However, the method has the disadvantage of using only the slope without considering the intercept. The purpose of this study was to verify our modification of the pain trajectory model including slope and intercept and to identify clusters.

METHODS

The pain intensity was measured in 60 patients after surgery, and we calculated their pain trajectories. The pain trajectory normally resolves in intensity over a period of days, and the linear fit of an individual patient's pain intensity score defines the trajectory. In this simple linear model (x axis, days; y axis, pain intensity), each patient's trajectory has the slope and the intercept. A multiple regression analysis model known as structural equation modeling was used to predict postoperative pain at 30 days after surgery. Finally, we performed hierarchical cluster analysis using the pain trajectory.

RESULTS

The slope and intercept model was the best fit among the models. Based on cluster analysis results, we created 4 pain trajectory groups (slope and intercept).

CONCLUSION

Our results suggest that the pain trajectory using the slope and intercept is quite useful for predicting postoperative pain at 30 days after surgery. Additionally, patients were classified into 4 groups using the slope and intercept. By considering both the slope and intercept, clinicians may be able to detect the risk for prolonged pain earlier than other methods.

Role of spinal cyclooxygenase-2 and prostaglandin E2 in fentanyl-induced hyperalgesia in rats

BACKGROUND

Accumulated evidence suggests that spinal cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) may be implicated in the development of opioid-induced hyperalgesia.

METHODS

Rats received subcutaneous fentanyl injections at different doses (20-80 μg kg^-1), four separate times at 15-min intervals. Some rats only received fentanyl (60 μg kg^-1 × 4 doses) with or without surgical incision. Fentanyl-induced hyperalgesia was evaluated via a tail-pressure or paw-withdrawal test. The concentrations of spinal COX-2, EP-1 receptor (EP-1R) mRNA, and PGE2 were measured. The effects of the COX-2 inhibitor, parecoxib (intraperitoneal 10 mg kg^-1), or the EP-1R antagonist, SC51089 (intraperitoneal 100 μg kg^-1), on hyperalgesia and spinal PGE2 were examined.

RESULTS

Acute repeated injections of fentanyl dose-dependently induced mechanical hyperalgesia, which reached a peak at the 1^st day and persisted for 1-4 days postinjection. This hyperalgesia could be partly or totally prevented by the pretreatment of either parecoxib or SC51089. Consistently, the levels of spinal COX-2 mRNA and PGE2 were also dose-dependently increased, reaching a peak at the first day and persisting for 2 days postinjection. Pretreatment with parecoxib could block the increase in spinal PGE2 and had no effects on spinal COX-2 and EP-1R mRNA. Fentanyl injection enhanced incision-induced mechanical and thermal hyperalgesia.

CONCLUSIONS

Acute repeated fentanyl administration dose-dependently produced mechanical hyperalgesia and augmented surgery induced postoperative hyperalgesia. This behavioural change was paralleled with an increase in spinal COX-2 mRNA and PGE2 after fentanyl administration. Inhibition of COX-2 or blockade of EP-1R can partly or totally prevent hyperalgesia.

Effects of anaesthesia and analgesia on long-term outcome after total knee replacement: A prospective, observational, multicentre study

BACKGROUND

Perioperative regional anaesthesia may protect from persistent postsurgical pain (PPSP) and improve outcome after total knee arthroplasty (TKA).

OBJECTIVES

Aim of this study was to evaluate the impact of regional anaesthesia on PPSP and long-term functional outcome after TKA.

DESIGN

A web-based prospective observational registry.

SETTING

Five Italian Private and University Hospitals from 2012 to 2015.

PATIENTS

Undergoing primary unilateral TKA, aged more than 18 years, informed consent, American Society of Anesthesiologists (ASA) physical status classes 1 to 3, no previous knee surgery.

INTERVENTION(S)

Personal data (age, sex, BMI and ASA class), preoperative pain assessed by numerical rating scale (NRS) score, and risk factors for PPSP were registered preoperatively. Data on anaesthetic and analgesic techniques were collected. Postoperative pain (NRS), analgesic consumption, major complications and patient satisfaction were registered up to the time of discharge. PPSP was assessed by a blinded investigator during a phone call after 1, 3 and 6 months, together with patient satisfaction, quality of life (QOL) and walking ability.

MAIN OUTCOME MEASURES

Experience of PPSP according to the type of peri-operative analgesia.

RESULTS

Five hundred sixty-three patients completed the follow-up. At 6 months, 21.6% of patients experienced PPSP, whereas autonomy was improved only in 56.3%; QOL was worsened or unchanged in 30.7% of patients and improved in 69.3%. Patients receiving continuous regional anaesthesia (epidural or peripheral nerve block) showed a lower NRS through the whole peri-operative period up to 1 month compared with both single shot peripheral nerve block and those who did not receive any type of regional anaesthesia. No difference was found between these latter two groups. Differences in PPSP at 3 or 6 months were not significantly affected by the type of anaesthesia or postoperative analgesia. A higher NRS score at 1 month, younger age, history of anxiety or depression, pro-inflammatory status, higher BMI and a lower ASA physical status were associated with a higher incidence of PPSP and worsened QOL at 6 months.

CONCLUSION

Continuous regional anaesthesia provides analgesic benefit for up to 1 month after surgery, but did not influence PPSP at 6 months. Better pain control at 1 month was associated with reduced PPSP. Patients with higher expectations from surgery, enhanced basal inflammation and a pessimistic outlook are more prone to develop PPSP.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02147730.

Effects of anaesthesia and analgesia on long-term outcome after total knee replacement: A prospective, observational, multicentre study

BACKGROUND

Perioperative regional anaesthesia may protect from persistent postsurgical pain (PPSP) and improve outcome after total knee arthroplasty (TKA).

OBJECTIVES

Aim of this study was to evaluate the impact of regional anaesthesia on PPSP and long-term functional outcome after TKA.

DESIGN

A web-based prospective observational registry.

SETTING

Five Italian Private and University Hospitals from 2012 to 2015.

PATIENTS

Undergoing primary unilateral TKA, aged more than 18 years, informed consent, American Society of Anesthesiologists (ASA) physical status classes 1 to 3, no previous knee surgery.

INTERVENTION(S)

Personal data (age, sex, BMI and ASA class), preoperative pain assessed by numerical rating scale (NRS) score, and risk factors for PPSP were registered preoperatively. Data on anaesthetic and analgesic techniques were collected. Postoperative pain (NRS), analgesic consumption, major complications and patient satisfaction were registered up to the time of discharge. PPSP was assessed by a blinded investigator during a phone call after 1, 3 and 6 months, together with patient satisfaction, quality of life (QOL) and walking ability.

MAIN OUTCOME MEASURES

Experience of PPSP according to the type of peri-operative analgesia.

RESULTS

Five hundred sixty-three patients completed the follow-up. At 6 months, 21.6% of patients experienced PPSP, whereas autonomy was improved only in 56.3%; QOL was worsened or unchanged in 30.7% of patients and improved in 69.3%. Patients receiving continuous regional anaesthesia (epidural or peripheral nerve block) showed a lower NRS through the whole peri-operative period up to 1 month compared with both single shot peripheral nerve block and those who did not receive any type of regional anaesthesia. No difference was found between these latter two groups. Differences in PPSP at 3 or 6 months were not significantly affected by the type of anaesthesia or postoperative analgesia. A higher NRS score at 1 month, younger age, history of anxiety or depression, pro-inflammatory status, higher BMI and a lower ASA physical status were associated with a higher incidence of PPSP and worsened QOL at 6 months.

CONCLUSION

Continuous regional anaesthesia provides analgesic benefit for up to 1 month after surgery, but did not influence PPSP at 6 months. Better pain control at 1 month was associated with reduced PPSP. Patients with higher expectations from surgery, enhanced basal inflammation and a pessimistic outlook are more prone to develop PPSP.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02147730

Dexmedetomidine Added to Sufentanil Patient-Controlled Intravenous Analgesia Relieves the Postoperative Pain after Cesarean Delivery: A Prospective Randomized Controlled Multicenter Study

This study evaluated the efficacy and safety of dexmedetomidine in intravenous patient-controlled analgesia (PCA) after cesarean delivery. This multicenter study enrolled 208 subjects who were scheduled for selective cesarean delivery from 9 research centers. Patients received 0.5 ug/kg dexmedetomidine (study group) or normal saline (control group) after delivery and an intravenous PCA pump after surgery (100 μg sufentanil +300 μg dexmedetomidine for the study group, 100 μg sufentanil for the control group, background infusion: 1 ml/h, bolus dose: 2 ml and lock time: 8 min). The sufentanil consumption, pain scores, rescue analgesia, sedation scores, analgesic satisfaction, the incidence of postoperative nausea and vomiting (PONV) and the first passage of flatus were recorded within 24 h after surgery. The sufentanil consumption in the study group was significantly lower than that in the control group (p = 0.004). Compared with the control group, the study group had lower pain scores (p < 0.01), higher analgesic satisfaction degree [p < 0.001, odd ratio 4.28 and 95% CI (2.46, 7.46)], less requirement of rescue analgesia (p = 0.003), lower incidence of PONV (p = 0.005 and p < 0.001, respectively), and shorter time to first passage of flatus (p = 0.007). Dexmedetomidine added to sufentanil intravenous PCA significantly enhanced the analgesic effects, improved analgesic satisfaction, and had the potential benefits of reducing PONV and the recovery of intestinal functions after cesarean section.

Benefit and harm of adding ketamine to an opioid in a patient-controlled analgesia device for the control of postoperative pain: systematic review and meta-analyses of randomized controlled trials with trial sequential analyses

Ketamine is often added to opioids in patient-controlled analgesia devices. We tested whether in surgical patients, ketamine added to an opioid patient-controlled analgesia decreased pain intensity by ≥25%, cumulative opioid consumption by ≥30%, the risk of postoperative nausea and vomiting by ≥30%, the risk of respiratory adverse effects by ≥50%, and increased the risk of hallucination not more than 2-fold. In addition, we searched for evidence of dose-responsiveness. Nineteen randomized trials (1349 adults, 104 children) testing different ketamine regimens added to various opioids were identified through searches in databases and bibliographies (to 04.2016). In 9 trials (595 patients), pain intensity at rest at 24 hours was decreased by 32% with ketamine (weighted mean difference -1.1 cm on the 0-10 cm visual analog scale [98% CI, -1.8 to -0.39], P < 0.001). In 7 trials (495 patients), cumulative 24 hours morphine consumption was decreased by 28% with ketamine (weighted mean difference -12.9 mg [-22.4 to -3.35], P = 0.002). In 7 trials (435 patients), the incidence of postoperative nausea and vomiting was decreased by 44% with ketamine (risk ratio 0.56 [0.40 to 0.78], P < 0.001). There was no evidence of a difference in the incidence of respiratory adverse events (9 trials, 871 patients; risk ratio 0.31 [0.06 to 1.51], P = 0.08) or hallucination (7 trials, 690 patients; odds ratio 1.16 [0.47 to 2.79], P = 0.70). Trial sequential analyses confirmed the significant benefit of ketamine on pain intensity, cumulative morphine consumption, and postoperative nausea and vomiting and its inability to double the risk of hallucination. The available data did not allow us to make a conclusion on respiratory adverse events or to establish dose-responsiveness.

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.

Patient Comprehension and Compliance Survey to Assess Postoperative Pain Regimens in the Orthopaedic Trauma Population

OBJECTIVE

This study aims to determine the groups of patients who are at risk for noncompliance and misunderstanding of their pain regimen.

DESIGN

Survey-based cohort study.

SETTING

Suburban Level-I trauma center.

PATIENTS/PARTICIPANTS

A total of 171 patients between the ages of 18-89 years who underwent surgical fixation of fractures involving the pelvis, long bones, or periarticular regions of the knee, ankle, elbow, and wrist.

MAIN OUTCOME MEASUREMENTS

Patients who cannot accurately reproduce their prescribed pain medication list and patients who modify this pain medication regimen were analyzed by age, employment status, income level, education level, time between surgery and follow-up, and whether pain interfered with activities of daily living.

RESULTS

Overall, 147 patients completed the survey. Seventy percent (n = 114) of patients could not accurately reproduce their pain medication regimen, regardless of age, employment status, income level, education level, time between surgery and follow-up, and whether pain interfered with activities of daily living. Patients (61.2%; n = 90), regardless of the 6 aforementioned demographic factors, also admitted to modifying their pain medication regimen with non-prescribed medications, with 55.8% (n = 82) of patients adding over-the-counter medications to surgeon-prescribed narcotic medications.

CONCLUSIONS

Misunderstanding and noncompliance of surgeon-prescribed pain regimens are prevalent across all patient demographics. Knowledge of the potential effects these augmentative medications can have on fracture healing and any drug-drug interactions that may arise is an important aspect of patient postoperative care. Surgeons must be wary of these trends and screen for any unintended side effects a patient's pain regimen may have.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Impact of different analgesic depths and abdominal trauma of different severities on stress and recovery of rats undergoing total intravenous anesthesia

A number of animal models have been developed to examine the pathophysiological consequences of surgical procedures, but anesthetic methods, monitoring, and management measures in these models are very different from those used in humans. This study was designed to create a rat model of abdominal surgery using anesthetic methods and perioperative treatment similar to those used in the clinic and to investigate the effects of different injury severities and depths of anesthesia and analgesia on surgical stress and postoperative recovery. Abdominal skin/muscle incision was compared with exploratory laparotomy in rats under propofol intravenous anesthesia, accompanied by perioperative measures such as oxygen inhalation, fluid infusion, warmth, blood gas analysis, and infection prevention. Stress indices (mean arterial pressure, heart rate, blood glucose, and plasma corticosterone) were monitored during anesthesia and surgery, and recovery indicators (body weight, food consumption, and pain) were measured after surgery. In addition, animals undergoing laparotomy were subjected to low and high dosages of propofol and sufentanil, in order to examine the relationship between anesthetic and analgesic depth and stress on recovery. Exploratory laparotomy induced a greater stress response and caused slower postoperative recovery as measured than somatic injury. High-dose sufentanil downregulated plasma corticosterone and improved postoperative recovery more effectively than high-dose propofol (P<0.05). Taken together, a rat model of abdominal surgery using anesthetic methods and perioperative treatment similar to those used in the clinic was successfully developed. It showed a positive correlation between severity of surgical trauma and stress response and postoperative recovery and a significant role of adequate analgesia in reducing surgical stress and improving postoperative recovery.

Comparison of the pro-postoperative analgesia of intraoperative dexmedetomidine with and without loading dose following general anesthesia: A prospective, randomized, controlled clinical trial

Intraoperative dexemdetomidine (DEX) with or without loading dose is well-established to improve postoperative pain control in patient-controlled analgesia (PCA). This study was designed to compare the pro-analgesia effect between the 2 in patients received general anesthesia.Seventy patients shceduced abdominal surgery under general anesthesia were randomly assigned into 3 groups which were maintained using propofol/remifentanil/Ringer solution (PRR), propofol/remifentanil/dexmedetomidine with (PRDw) or without (PRDo) a loading dose of dexmedetomidine before induction.PRDw/o patients displayed a greater Romsay sedation score measured immediately after surgery. When compared with PRR patients, those from the PRDw/o group had an increased time to first request of postoperative morphine and decreased 24 hours total morphine consumption. No significant difference was observed between patients from the PRDw and PRDo groups with respect to these parameters.The present study suggests that the administration of a DEX loading dose does not affect the pro-analgesic effect of intraoperative use of DEX on morphine-based PCA.

A new model of nerve injury in the rat reveals a role of Regulator of G protein Signaling 4 in tactile hypersensitivity

Tactile hypersensitivity is one of the most debilitating symptoms of neuropathic pain syndromes. Clinical studies have suggested that its presence at early postoperative stages may predict chronic (neuropathic) pain after surgery. Currently available animal models are typically associated with consistent tactile hypersensitivity and are therefore limited to distinguish between mechanisms that underlie tactile hypersensitivity as opposed to mechanisms that protect against it. In this study we have modified the rat model of spared nerve injury, restricting the surgical lesion to a single peripheral branch of the sciatic nerve. This modification reduced the prevalence of tactile hypersensitivity from nearly 100% to approximately 50%. With this model, we here also demonstrated that the Regulator of G protein Signaling 4 (RGS4) was specifically up-regulated in the lumbar dorsal root ganglia and dorsal horn of rats developing tactile hypersensitivity. Intrathecal delivery of the RGS4 inhibitor CCG63802 was found to reverse tactile hypersensitivity for a 1h period. Moreover, tactile hypersensitivity after modified spared nerve injury was most frequently persistent for at least four weeks and associated with higher reactivity of glial cells in the lumbar dorsal horn. Based on these data we suggest that this new animal model of nerve injury represents an asset in understanding divergent neuropathic pain outcomes, so far unravelling a role of RGS4 in tactile hypersensitivity. Whether this model also holds promise in the study of the transition from acute to chronic pain will have to be seen in future investigations.

Future Perspectives of ERAS: A Narrative Review on the New Applications of an Established Approach

ERAS approach (Enhanced Recovery After Surgery) is a multimodal, perioperative pathway designed to achieve early recovery after surgery. ERAS has shown documented efficacy in elective surgery, and the concept of "multimodal" and "multidisciplinary" approach seems still to be of higher importance than each single item within ERAS protocols. New perspectives include the use of ERAS in emergency surgery, where efficacy and safety on outcome have been documented, and flexibility of traditional items may add benefits for traditionally high-risk patients. Obstetric surgery, as well, may open wide horizons for future research, since extremely poor data are currently available, and ERAS benefits may translate even on the baby. Finally, the concept of "outcome" may be extended when considering the specific setting of cancer surgery, in which variables like cancer recurrence, early access to adjuvant therapies, and, finally, long-term survival are as important as the reduced perioperative complications. In this perspective, different items within ERAS protocols should be reinterpreted and eventually integrated towards "protective" techniques, to develop cancer-specific ERAS approaches keeping pace with the specific aims of oncologic surgery.

Sex Differences in the Morphine-Sparing Effects of Intraoperative Dexmedetomidine in Patient-Controlled Analgesia Following General Anesthesia: A Consort-Prospective, Randomized, Controlled Clinical Trial

Previous studies have reported that intraoperative dexmedetomidine has morphine-sparing effects in patient-controlled analgesia (PCA). The present study was designed to investigate the possible sex differences in the morphine-sparing effects of intraoperative dexmedetomidine following general anesthesia. A total of 223 patients scheduled for surgeries under general anesthesia were divided into female and male groups. Each group was then subdivided into 2 subgroups that were maintained using propofol/remifentanil/dexmedetomidine (PRD) or propofol/remifentanil/saline (PRS). During the first 24 hours postsurgery, both female and male PRD patients had lower scores on a visual analog scale (VAS) (fPRS vs fPRD, P < 0.05 or P < 0.01; mPRS mPRD, P < 0.05, P < 0.01, or P < 0.001) and consumed less morphine than their controls from the PRS group (fPRS vs fPRD, P = 0.0392; mPRS vs mPRD, P = 0.0041). Interestingly, the female PRD patients had similar VAS scores (fPRD vs mPRD, P > 0.05) and consumed comparable morphine compared to the male PRD patients (fPRD vs mPRD, P = 0.4238). However, when normalized to body weight, they consumed much more morphine than male PRD patients (fPRD vs mPRD, P < 0.001), and this effect was not seen in the PRS patients. Intraoperative administration of dexmedetomidine appeared to have a stronger morphine-sparing effect in controlling postoperative acute pain in male patients than in female patients.

Effect of Preoperative Inflammatory Status and Comorbidities on Pain Resolution and Persistent Postsurgical Pain after Inguinal Hernia Repair

Poor acute pain control and inflammation are important risk factors for Persistent Postsurgical Pain (PPSP). The aim of the study is to investigate, in the context of a prospective cohort of patients undergoing hernia repair, potential risk factors for PPSP. Data about BMI, anxious-depressive disorders, neutrophil-tolymphocyte ratio (NLR), proinflammatory medical comorbidities were collected. An analysis for correlation between comorbidities and PPSP was performed in those patients experiencing chronic pain at 3 months after surgery. Tramadol resulted less effective in pain at movement in patients with a proinflammatory status. Preoperative hypertension and NLR > 4 were correlated with PPSP intensity. Regional anesthesia was significantly protective on PPSP when associated with ketorolac. Patients with pain at 1 month were significantly more prone to develop PPSP at 3 months. NSAIDs or weak opioids are equally effective on acute pain and on PPSP development after IHR, but Ketorolac has better profile in patients with inflammatory background or undergoing regional anesthesia. Drug choice should be based on their potential side effects, patient's profile (comorbidities, preoperative inflammation, and hypertension), and type of anesthesia. Close monitoring is necessary to early detect pain conditions more prone to progress to a chronic syndrome.

Intraoperative Dexmedetomidine Promotes Postoperative Analgesia and Recovery in Patients after Abdominal Hysterectomy: a Double-Blind, Randomized Clinical Trial

Surgery-induced acute postoperative pain and stress response can lead to prolonged convalescence. The present study was designed to investigate the effects of intraoperative dexmedetomidine on postoperative analgesia and recovery following abdominal hysterectomy surgeries. Sixty-four patients scheduled for abdominal hysterectomy under general anesthesia were divided into two groups that were maintained using propofol/remifentanil/dexmedetomidine (PRD) or propofol/remifentanil/saline (PRS). During surgery, patients in the PRD group had a lower bispectral index (BIS) value, which indicated a deeper anesthetic state, and a higher sedation score immediately after extubation than patients in the PRS group. During the first 24 hours post-surgery, PRD patients consumed less morphine with patient-controlled analgesia (PCA) and had lower scores on a visual analogue scale (VAS) than their controls from the PRS group. The global 40-item quality of recovery questionnaire and 9-question fatigue severity score both showed higher recovery scores from day 3 after surgery in the PRD group. with the data are considered together, intraoperative administration of dexmedetomidine appeared to promote the analgesic properties of morphine-based PCA and to expedite recovery following surgery in patients undergoing abdominal hysterectomy.

Intraoperative Dexmedetomidine Promotes Postoperative Analgesia in Patients After Abdominal Colectomy: A Consort-Prospective, Randomized, Controlled Clinical Trial

Surgery-induced acute postoperative pain may lead to prolonged convalescence. The present study was designed to investigate the effects of intraoperative dexmedetomidine on postoperative analgesia following abdominal colectomy surgeries. Eighty patients scheduled for abdominal colectomy surgery under general anesthesia were divided into 2 groups, which were maintained using propofol/remifentanil/dexmedetomidine (PRD) or propofol/remifentanil/saline (PRS). During surgery, patients in the PRD group had a lower bispectral index (BIS) value, which indicated a deeper anesthetic state, and a higher sedation score right after extubation than patients in the PRS group. During the first 24 hours post surgery, PRD patients consumed less morphine in patient-controlled analgesia (PCA) and had a lower score in the visual analog scale (VAS) testing than their controls from the PRS group. Intraoperative administration of dexmedetomidine appears to promote the analgesic property of morphine-based PCA in patients after abdominal colectomy.

Effect of postoperative analgesia on acute and persistent postherniotomy pain: a randomized study

STUDY OBJECTIVE

The study objective is to identify differences in postoperative pain management according to different analgesic treatments, targeting 2 main pathways involved in pain perception.

DESIGN

The design is a randomized, parallel groups, open-label study.

SETTING

The setting is in an operating room, postoperative recovery area, and surgical ward.

PATIENTS

There are 200 patients undergoing open inguinal hernia repair (IHR) with tension-free technique (mesh repair).

INTERVENTIONS

The intervention is a randomization to receive ketorolac (group K) or tramadol (group T) for 3 days after surgery.

MEASUREMENTS

The measurements are differences in analgesic efficacy (numeric rating scale [NRS]) in the postoperative (up to 5 days) period, chronic pain incidence (1 and 3 months), side effects, and complications.

MAIN RESULTS

We found no differences in analgesic efficacy (NRS value ≥4 in the first 96 hours: 26% in group K vs 32% in group T, P = .43); the proportion of patients with NRS ≥4 was similar in both groups, and the time trajectories were not significantly different (P for interaction = .24). Side effects were higher (12% vs 6%) in the tramadol group, although not significantly (P = .14), with a case of bleeding in the ketorolac group and higher incidence of constipation in tramadol group. One patient in each group developed chronic pain.

CONCLUSIONS

Ketorolac or weak opioids are equally effective on acute pain and on persistent postsurgical pain development after IHR, and drug choice should be based on their potential side effects and patient's comorbidities. Further studies are needed to standardize the most rational approach to prevent persistent postsurgical pain after IHR.

Continuous wound infusion of local anesthetic and steroid after major abdominal surgery: study protocol for a randomized controlled trial

Background

Inflammatory response is one of the key components of pain perception. Continuous infusion (CWI) of local anesthetics has been shown to be effective in controlling pain and reducing postoperative morphine consumption, but the effect of adding a potent anti-inflammatory drug (such as a steroid) has never been addressed. In our study, we want to investigate the effect of CWI with local anesthetic + methylprednisolone on acute and persistent pain, correlating clinical data with biomarkers of inflammation and genetic background.

Methods/Design

After approval by their institutional review board, three hospitals will enroll 120 patients undergoing major abdominal surgery in a randomized, double-blind, phase III study. After a 24-h CWI of ropivacaine 0.2 % + methylprednisolone 1 mg/kg, patients will be randomly assigned to receive either ropivacaine + steroid or placebo for the next 24 h. Then, patient-controlled CWI with only ropivacaine 0.2 % or placebo (according to the group of randomization) is planned after 48 h up to 7 days (bolus 10 ml, lock-out 1 h, maximum dose of 40 ml in 4 h). Morphine equivalent consumption up to 7 days will be analyzed, together with any catheter- or drug-related side effect. Persistent post-surgical pain (PPSP) incidence will also be investigated. Our primary endpoint is analgesic consumption in the first 7 days after surgery; we will evaluate, as secondary endpoints, any catheter- or drug-related side effect, genotype/phenotype correlations between some polymorphisms and postoperative outcome in terms of morphine consumption, development of the inflammatory response, and incidence of PPSP. Finally, we will collect, in a subgroup of patients, wound exudate samples by micro-dialysis, blood samples, and urine samples up to 72 h to investigate local and systemic inflammation and oxidative stress.

Discussion

This is a phase III trial to evaluate the safety and efficacy of wound infusion with steroid and local anesthetic. The study is aimed also to evaluate how long this infusion has to be maintained in order to maximize effectiveness. Our data are intended to quantify the amount of ropivacaine and methylprednisolone needed by patients undergoing major abdominal surgery, to be stored in a new nanotechnology device for sustained pain treatment after surgery. We also aim to clarify the roles of inflammatory response, oxidative stress, and genetic background on postoperative and persistent pain after major abdominal surgery.

Trial registration

The trial was registered on ClinicalTrials.gov (NCT02002663) on 24 Oct. 2013.

Dexmedetomidine in Postoperative Analgesia in Patients Undergoing Hysterectomy: A CONSORT-Prospective, Randomized, Controlled Trial

Both dexmedetomidine and sufentanil modulate spinal analgesia by different mechanisms, and yet no human studies are available on their combination for analgesia during the first 72 hours after abdominal hysterectomy.This CONSORT-prospective, randomized, double-blinded, controlled trial sought to evaluate the safety and efficacy of the combination of dexmedetomidine and sufentanil in intravenous patient-controlled analgesia (PCA) for 72 hours after abdominal hysterectomy.Ninety women undergoing total abdominal hysterectomy were divided into 3 equal groups that received sufentanil (Group C; 0.02 μg/kg/h), sufentanil plus dexmedetomidine (Group D1; 0.02 μg/kg/h, each), or sufentanil (0.02 μg/kg/h) plus dexmedetomidine (0.05 μg/kg/h) (Group D2) for 72 hours after surgery in this double-blinded, randomized study. The primary outcome measure was the postoperative sufentanil consumption, whereas the secondary outcome measures were pain intensity (visual analogue scale), requirement of narcotic drugs during the operation, level of sedation, Bruggrmann comfort scale, and concerning adverse effects.The postoperative sufentanil consumption was significantly lower in Groups D1 and D2 than in Group C during the observation period (P < 0.05), but lower in Group D2 than in Group D1 at 24, 48, and 72 hours after surgery (P < 0.05). The heart rate after intubation and incision was lower in Groups D1 and D2 than in Group C (P < 0.05). On arrival at the recovery room, Groups D1 and D2 had lower mean blood pressure than Group C (P < 0.05). The intraoperative requirement of sevoflurane was 30% lesser in Groups D1 and D2 than in Group C. The sedation levels were greater in Groups D1 and D2 during the first hour (P < 0.05). Compared with Groups C and D1, Group D2 showed lower levels of the overall incidence of nausea and vomiting (P < 0.05).Among the tested PCA options, the addition of dexmedetomidine (0.05 μg/kg/h) and sufentanil (0.02 μg/kg/h) showed better analgesic effect and greater patient satisfaction without other clinically relevant side effects for patients undergoing hysterectomy during the first 72 hours after abdominal hysterectomy.

Prolonged opioid use after knee arthroscopy in military veterans

BACKGROUND

Chronic postoperative pain occurs with an appreciable incidence after elective surgery. Known risk factors include perioperative pain and posttraumatic stress disorder (PTSD). Military veterans are a population at particular risk for PTSD and hence may be at increased risk for chronic pain after surgery. Our goal was to identify risk factors for chronic postoperative pain in young veterans after minor elective surgery, including the contribution of PTSD.

METHODS

We reviewed the medical and pharmacy records of veterans (18-50 years old), undergoing elective knee arthroscopy from 2007 to 2010 at the Veteran's Administration Puget Sound Health Care System. The data included demographics, ASA physical status class, comorbidities, anesthesia medications, and opioid prescriptions starting 3.5 months before surgery and ending 3.5 months after surgery. We documented the presence of PTSD based on either the patient's problem list or the clinical notes. We used prolonged postoperative opioid prescription longer than 3 months after surgery as a surrogate for chronic postoperative pain.

RESULTS

We identified 145 patients who met inclusion criteria. The median age was 39 ± 8 years old. Eighty-seven percent of the patients were men. The prevalence of PTSD was 32% (95% confidence interval, 25%-41%). PTSD was associated with increased incidence of smoking (P = 0.009) and preoperative opioid use (P = 0.0006). Preoperative opioids were prescribed in 44% (63 of 145) of the patients: in 64% (30 of 47) of patients with PTSD, compared with 34% (33 of 98) in patients without PTSD (P = .0006). Chronic postoperative pain was identified in 30% (43 of 145) of patients. The strongest independent predictor of chronic postoperative pain was an opioid prescription before surgery (odds ratio = 65.3; 95% confidence interval, 014.5-293.0). In patients older than 27.5 years who did not receive opioids before surgery, PTSD may also have been a risk factor for chronic postoperative pain.

CONCLUSIONS

This single-center retrospective study suggests that the most important predictor of chronic postoperative pain is preoperative opioid use. For patients not taking opioids preoperatively, PTSD may increase the risk of prolonged postoperative opioid prescriptions and chronic postoperative pain, potentially related to patient age.

Pain after knee arthroplasty: an unresolved issue

PURPOSE

Despite the recent advances in the understanding of pain mechanisms and the introduction of new drugs and new techniques in the postoperative management, pain after total knee arthroplasty (TKA) is still an unresolved issue. It affects the quality of life and rehabilitation of an important percentage of patients undergoing TKA. The aim of this narrative review was to give an overview on pain mechanisms and multimodal pain management.

METHODS

A review of all peer-reviewed articles on pain after knee arthroplasty was performed by two reviewers. Recent articles on incisional pain mechanisms were included because of their importance in the understanding of postsurgical pain. Search was performed in Pubmed, Cochrane and Google Scholar data bases.

RESULTS

Postsurgical pain mechanisms are based on both local and systemic inflammatory reactions. Peri-operative pain management starts with the anaesthetic technique and resides on a multimodal analgesia regimen. New concepts, drugs and techniques have shown their efficacy in reducing the severity of acute postoperative pain and the risk of developing chronic pain after TKA.

CONCLUSION

This narrative review offers a clear overview of pain mechanism after knee arthroplasty and an understanding on how multimodal pain management can reduce the intensity and duration of pain after knee arthroplasty.

Exogenous and endogenous opioid-induced pain hypersensitivity in different rat strains

BACKGROUND

Opioid-induced hyperalgesia (OIH) is a recognized complication of opioid use that may facilitate the development of exaggerated postoperative pain.

OBJECTIVE

To examine the role of genetic factors on OIH by comparing four rat strains. Because the authors previously reported that the endogenous opioids released during non-nociceptive environmental stress induce latent pain sensitization, genetic and environmental factor interactions were also evaluated.

METHODS

First, the propensity of Sprague Dawley, Wistar, Lewis and Fischer rats to develop OIH following single or repeated fentanyl exposures was compared by measuring the nociceptive threshold using the paw pressure vocalization test. Second, Sprague Dawley and Fischer rats were exposed to a series of three non-nociceptive environmental stress sessions to evaluate the ability of endogenous opioids to enhance hyperalgesia associated with a carrageenan-induced hind-paw inflammation test performed two weeks later.

RESULTS

Sprague Dawley, Wistar and Lewis rats exhibited OIH, although differences were observed. OIH was not observed in Fischer rats. Inflammatory hyperalgesia enhancement induced through previous stress in Sprague Dawley rats was not observed in Fischer rats.

CONCLUSIONS

The pain level not only reflects nociceptive inputs but also depends on both the history and genetic factors of the individual. Genetic and environmental models may provide new insights into the mechanisms that underlie individual differences observed in postoperative pain.

Femoral nerve block: Assessment of postoperative analgesia in arthroscopic anterior cruciate ligament reconstruction

BACKGROUND AND OBJECTIVES

Knee anterior cruciate ligament reconstruction (ACLR) may be painful in the postoperative period. The primary objective of this study was to evaluate whether the use of femoral nerve block (FNB) associated with spinal anesthesia would improve the postoperative pain treatment in ACLR and the secondary objectives were to evaluate tramadol request and adverse events.

METHOD

53 patients were randomly divided into two groups: GA (n =26) received spinal anesthesia and GB (n = 27) received spinal anesthesia and FNB. All patients received multimodal analgesia and rescue analgesics could be requested anytime. Assessments were performed at 6, 12 and 24 hours.

RESULTS

There was no difference between both groups regarding demographic and clinical- surgical variables. There was no difference between groups regarding pain intensity. Mean pain scores were higher at 12 hours in GA and there was no change in GB; 55.6% of patients reported moderate pain in GA and 53.8% mild pain in GB. There was no difference regarding tramadol request. There were no serious adverse events: 80.8% of patients in GB had motor block of the thigh and two fell.

CONCLUSIONS

Analgesia was more effective with the combination of spinal and FNB, which allowed better control of postoperative pain, assessed 12 hours after anesthesia. There was no difference in tramadol request. Patients in this study had no serious adverse events; however, one must be attentive to motor paralysis and the possibility of falling when FNB is performed.

Recent management advances in acute postoperative pain

INTRODUCTION

Acute postoperative pain remains a major problem, with both undertreatment and overtreatment leading to serious consequences, including increased risk of persistent postoperative pain, impaired rehabilitation, increased length of stay and/or hospital readmission, and adverse events related to excessive analgesic use, such as oversedation. New analgesic medications and techniques have been introduced that target the preoperative, intraoperative, and postoperative periods to better manage acute postoperative pain, with improvements in analgesic efficacy and safety over more traditional pain management approaches. This review provides an overview of these new analgesic medications and techniques. Specific topics that are discussed include the use of preoperative nonsteroidal anti-inflammatory drugs, anxiolytics, and anticonvulsants; intraoperative approaches such as neuraxial analgesia, continuous local anesthetic wound infusion, transversus abdominis plane block, extended-release epidural morphine, intravenous acetaminophen, and intravenous ketamine; and postoperative use of intravenous ibuprofen, new opioids (eg, tapentadol) or opioid formulations (morphine-oxycodone), and patient-controlled analgesia.

CONCLUSION

New, targeted, analgesic medications and techniques may provide a safer and more effective approach to the management of acute postoperative pain than traditional approaches such as postoperative oral analgesics.

Medical management of acute pain in patients with chronic pain

The number of patients with chronic pain has increased over the years, as well as the number of patients who manage chronic pain with opioids. As prescribed opioid use has increased, so has its abuse and misuse. It has also been estimated that the number of people using opioids illicitly has doubled worldwide over the last 20 years. Management of chronic pain with opioids is associated with pathophysiological phenomena such as tolerance, dependence and hyperalgesia. They can become a problem when chronic pain patients present for a surgical procedure. Furthermore, patients who are on opioids on a regular basis require higher amounts during the perioperative period. The perioperative management of the chronic pain patient is difficult and complex. Developing an appropriate plan that can fulfill patients' and surgical team's needs requires skills and experience. The aim of this review is to describe the options available for the optimal perioperative management of acute pain in patients with a history of chronic pain.

[Do anesthetic techniques influence postoperative outcomes? Part II]

The knowledge of the influence of anesthetic techniques in postoperative outcomes has opened a large field of research in recent years. In this second part, we review some of the major controversies arising from the literature on the impact of anesthetic techniques on postoperative outcomes in 6 areas: postoperative cognitive dysfunction, chronic postoperative pain, cancer recurrence, postoperative nausea/vomiting, surgical outcomes, and resources utilization. The development of protective and preventive anesthetic strategies against short and long-term postoperative complications will probably occupy an important role in our daily anesthetic practice. Dynamic postoperative pain control has been confirmed as one of the basic requirements of accelerated postoperative recovery programs ("fast-track surgery"), and it is also a preventive factor for development of chronic postoperative pain. The weight of anesthetic technique on postoperative immunosuppression is to be defined. The potential influence of anesthesia on cancer recurrence, is a highly controversial area of research. The classic pattern of perioperative fluid therapy may increase postoperative complications. On the other hand, the maintenance of normoglycemia and normothermia was associated with a decreased postoperative morbidity. The high volume of surgical procedures means that the adequacy of human, organizational and technological resources have a major impact on overall costs.