Current status of pre-emptive analgesia

Intra- and post-operative outcomes of the Enhanced Recovery after Surgery (ERAS) Program in laparoscopic hysterectomy

PURPOSE

To investigate the effect of the Enhanced Recovery After Surgery (ERAS) protocol on perioperative and post-operative outcomes in laparoscopic hysterectomies (LHs) performed for benign gynecological diseases.

METHODS

This prospective study was conducted with randomized 100 participants who underwent LH between 1 January and 31 December, 2022. A standard care protocol was applied to 50 participants (Group 1, control) and the ERAS protocol to the other 50 (Group 2, study). Length of hospitalization was compared between the groups as the primary outcome, and the duration of the operation, the amount of bleeding, post-operative nausea-vomiting, gas discharge time, visual analog scale (VAS) pain scores, and complications as the secondary outcomes.

RESULTS

No statistically significant difference was seen between the groups in terms of sociodemographic characteristics, medical history, operation indications, surgical procedures applied in addition to hysterectomy, operative time, pre-operative and post-operative hemoglobin levels, amount of bleeding, or drain use (p > 0.05). However, a statistically significant difference was observed in terms of nausea (60% vs. 26%, p = 0.001), vomiting (28% vs. 10%, p = 0.040), duration of gassing (17.74 ± 6.77 vs. 14.20 ± 7.05 h, p = 0.012), length of hospitalization (41.78 ± 12.17 vs. 34.12 ± 10.90 h, p = 0.001), analgesic requirements (4.62 ± 1.36 vs. 3.34 ± 1.27 h, p < 0.001), or VAS scores at the 1st (5.86 ± 1.21 vs. 4.58 ± 1.31, p < 0.001), 6th (5.16 ± 1.12 vs. 4.04 ± 1.08, p < 0.001), 12th (4.72 ± 1.12 vs. 3.48 ± 1.12, p < 0.001), 18th (4.48 ± 1.21 vs. 3.24 ± 1.34, p < 0.001), and 24th (4.08 ± 1.29 vs. 3.01 ± 1.30, p < 0.001) hours.

CONCLUSION

The findings of this study show that the ERAS protocol has a positive effect on peri- and post-operative outcomes in LH. Further prospective studies are now needed to confirm the validity of the results.

Effect of subanesthetic dose of esketamine on postoperative pain in elderly patients undergoing laparoscopic gastrointestinal tumor Surgery:A prospective, double-blind, randomized controlled trial

Purpose

Postoperative pain is prevalent and severe complication in elderly surgical patients. Multiple studies propose that a small dose of esketamine administered intraoperatively can alleviate postoperative pain and curtail opioid usage. We aimed to evaluate the impact of esketamine on postoperative acute pain among elderly patients with gastrointestinal tumors.

Patients and methods

This is a prospective, parallel-group, randomized controlled trial. Ninety patients aged 60 and above, undergoing resection of gastrointestinal tumors, were randomly assigned to two groups: esketamine group (Group S, a single dose of 0.25 mg/kg and 0.1 mg/kg/h infusion) and control group (Group C, saline). Visual Analogue Scale (VAS) pain scores were the primary outcome. Remifentanil consumption, instances of rescue analgesia, delirium, sleep quality, postoperative recovery quality, serum levels of inflammatory cytokines, and adverse events within 72 h post-surgery were secondary outcomes, respectively.

Results

Data of 87 of 99 eligible patients were analyzed. VAS scores at rest in Group S were lower than those in Group C at 6 h [1.2 (0.6, 1.6) vs 1.6 (1.0, 2.0), P = 0.003], 12 h [1.4 (1.0, 2.0) vs 2.0 (1.5, 2.0), P < 0.001], and 24 h [1.8 (1.3, 2.0) vs 2.2 (1.6, 2.6), P < 0.001] postoperatively. At 6 h post-surgery, VAS score during coughing was lower in Group S than Group C [2.0 (2.0, 2.3) vs 2.0 (2.0, 3.0), P = 0.009]. The instances of rescue analgesia were fewer in group S compared to group C (P = 0.007). Furthermore, the esketamine group showed improved sleep quality and QoR-15 score (P < 0.05) postoperatively.

Conclusion

Intravenous administration of esketamine as an adjunct to general anesthesia can decrease the intensity of pain for 24 h without additional adverse effects after laparoscopic gastrointestinal tumor surgery.

Regional Anesthesia Is Safe and Effective for Low-Energy Tibial Plateau Fractures

The purpose of this study was to determine if the use of peripheral nerve blocks in the operative management of tibial plateau fractures is associated with improved outcomes when compared with the use of spinal and general anesthesia. Over a period of 16 years, 132 patients who underwent operative repair for a low-energy tibial plateau fracture and had at least 12 months of follow-up met the inclusion criteria and formed the basis of this study. Patients were grouped into cohorts based on the anesthetic method used during surgery: peripheral nerve block in combination with conscious sedation or general anesthesia (BA), general anesthesia alone (GA), or spinal anesthesia alone (SA). Outcomes were assessed at 3 months, 6 months, and 12 months. Length of stay was greatest in the GA cohort (P<.05), and more patients in the BA cohort were discharged to home (P<.05). Patients in the GA cohort had the highest pain scores at 3 months and 6 months (P<.05). Patients in both the SA and BA cohorts had better Short Musculoskeletal Function Assessment scores at 6 and 12 months when compared with the GA cohort (P<.05). Although knee range of motion did not differ among the three cohorts at 3 months, it did differ at 6 months and 12 months postoperatively, with those who had a preoperative nerve blockade (SA and BA) having the greatest knee range of motion (P<.05). Regional anesthesia was safe and was associated with lower pain scores in the early postoperative period and greater knee range of motion and functional outcome scores in the late postoperative period. [Orthopedics. 2023;46(6):358-364.].

Contribution to the Study of Perioperative Factors Affecting the Restoration of Dog's Mobility after Femoral Head and Neck Excision: A Clinical Study in 30 Dogs

This study aimed to compare postoperative analgesia and the time of limb weight bearing induced by the intraoperative administration of a local anesthetic at the site of the femoral head and neck excision (FHNE) in dogs, with and without the administration of preoperative epidural anesthesia. Additionally, the impact of postoperative opioid drug administration on weight-bearing time was examined. This randomized, blinded, prospective clinical study included 30 client-owned dogs. The dogs were randomly divided into three groups (A, B, C), each further divided into two subgroups (A1, A2, B1, B2, C1, C2). Group A received epidural anesthesia and ropivacaine at the ostectomy site, Group B received only ropivacaine, and Group C served as the control group. Subgroup 1 received a non-steroidal anti-inflammatory drug postoperatively, while Subgroup 2 had tramadol added to their regimen. Pain assessment was conducted using the University of Melbourne Pain Scale (UMPS) and an algometer. The study concluded that multimodal analgesia, utilizing all the aforementioned analgesic techniques, resulted in faster limb weight bearing for dogs undergoing FHNE.

Use of Pregabalin as Preemptive Analgesia for Decreasing Postoperative Pain in Tympanoplasty

Tympanoplasty is a commonly performed surgical procedure done by Otorhinolaryngologist for treatment of chronic suppurative otitis media. Postoperative period requires the use of analgesics which are given regularly. The study aims to assess the efficacy of a single dose of preemptive pregabalin in decreasing postoperative pain after postauricular type 1 tympanoplasty. This randomized prospective study was carried out in a tertiary care hospital between July 2017 and April 2018. A total of 60 patients were divided into two groups of 30 each. This study analyzed the effect of single preoperative use of pregabalin 150 mg oral 1 h before type 1 postauricular tympanoplasty for postoperative pain as a VAS (visual analogue scale) score and requirement of rescue analgesia and results were compared with the placebo group. Pain scores (VAS score) was significantly lower in the pregabalin group as compared to the placebo group at 6, 12, 24, and at 48 h. Rescue analgesia requirements were also lower in the pregabalin group than the placebo group. Preemptive use of a single dose of oral 150 mg pregabalin reduces postoperative pain and rescue analgesic requirement in patients undergoing type 1 tympanoplasty.

Perioperative use of physostigmine to reduce opioid consumption and peri-incisional hyperalgesia: a randomised controlled trial

BACKGROUND

Several studies have shown that cholinergic mechanisms play a pivotal role in the anti-nociceptive system by acting synergistically with morphine and reducing postoperative opioid consumption. In addition, the anti-cholinesterase drug physostigmine that increases synaptic acetylcholine concentrations has anti-inflammatory effects.

METHODS

In this randomised placebo-controlled trial including 110 patients undergoing nephrectomy, we evaluated the effects of intraoperative physostigmine 0.5 mg h^-1 i.v. for 24 h on opioid consumption, hyperalgesia, pain scores, and satisfaction with pain control.

RESULTS

Physostigmine infusion did not affect opioid consumption compared with placebo. However, the mechanical pain threshold was significantly higher (2.3 [sd 0.3]) vs 2.2 [0.4]; P=0.0491), and the distance from the suture line of hyperalgesia (5.9 [3.3] vs 8.5 [4.6]; P=0.006), wind-up ratios (2.2 [1.5] vs 3.1 [1.5]; P=0.0389), and minimum and maximum postoperative pain scores at 24 h (minimum 1.8 [1.0] vs 2.4 [1.2]; P=0.0451; and maximum 3.2 [1.4] vs 4.2 [1.4]; P=0.0081) and 48 h (minimum 0.9 [1.0] vs 1.6 [1.1]; P=0.0101; and maximum 2.0 [1.5] vs 3.2 [1.6]; P=0.0029) were lower in the study group. Pain Disability Index was lower and satisfaction with pain control was higher after 3 months in the physostigmine group.

CONCLUSIONS

In contrast to previous trials, physostigmine did not reduce opioid consumption. As pain thresholds were higher and hyperalgesia and wind-up lower in the physostigmine group, we conclude that physostigmine has anti-hyperalgesic effects and attenuates sensitisation processes. Intraoperative physostigmine may be a useful and safe addition to conventional postoperative pain control.

CLINICAL TRIAL REGISTRATION

EudraCT number 2012-000130-19.

From Patient-Controlled Analgesia to Artificial Intelligence-Assisted Patient-Controlled Analgesia: Practices and Perspectives

Pain relief is a major concern for patients who have undergone surgery, and it is an eternal pursuit for anesthesiologists. However, postoperative pain management is far from satisfactory, though the past decades have witnessed great progress in the development of novel analgesics and analgesic techniques. A Cochrane systematic review showed that patient-controlled analgesia (PCA) achieved better pain relief and greater patient satisfaction than traditional “on-demand” parenteral analgesia, suggesting that it might be the manner of analgesia implementation that matters for effective postoperative pain management. A wireless intelligent PCA (Wi-PCA) system that incorporated remote monitoring, an intelligent alarm, intelligent analysis and assessment of the PCA equipment, as well as automatically recording and reserving key information functions under a wireless environment was introduced in our department in 2018. The practice showed that the Wi-PCA system significantly reduced the incidence of moderate to severe postoperative pain and relevant adverse effects, shortened hospital stays, and improved patient satisfaction with postoperative pain relief. Nevertheless, for both traditional and Wi-PCA, analgesics are only administered when pain occurs, leaving behind a realm of possibilities for better postoperative pain management. With the rapid development of machinery and deep learning algorithms, artificial intelligence (AI) is changing the mode of clinical decision making. Integrating the big data collected by state-of-the-art monitoring sensors, the Internet of Things and AI algorithms, an AI-assisted PCA (Ai-PCA) may be a promising future direction for postoperative pain management.

Postoperative pain pathophysiology and treatment strategies after CRS + HIPEC for peritoneal cancer

Background

Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is a treatment choice for peritoneal cancer. However, patients commonly suffer from severe postoperative pain. The pathophysiology of postoperative pain is considered to be from both nociceptive and neuropathic origins.

Main body

The recent advances on the etiology of postoperative pain after CRS + HIPEC treatment were described, and the treatment strategy and outcomes were summarized.

Conclusion

Conventional analgesics could provide short-term symptomatic relief. Thoracic epidural analgesia combined with opioids administration could be an effective treatment choice. In addition, a transversus abdominis plane block could also be an alternative option, although further studies should be performed.

Effects of a single dose of preoperative pregabalin and gabapentin for acute postoperative pain: a network meta-analysis of randomized controlled trials

Background

Pregabalin (PGB) and gabapentin (GBP) are current and emerging drugs in the field of pre-emptive preoperative analgesia. However, the role of PGB or GBP in acute postoperative pain management still remains elusive.

Materials and methods

We conducted a comprehensive literature search of articles published by December 3, 2017. A total of 79 randomized controlled trials with 6,201 patients receiving single-dose premedication were included. Through a network meta-analysis (NMA), we validated the analgesic effect and incidence of adverse events by using various doses of PGB or GBP administration.

Results

NMA results suggested that the analgesic effect may be dose related. For 24-hour opioid consumption, a consistent decrease was found with the increase in the dose of PGB or GBP. For 24-hour pain score at rest, a high dose (≥150 mg) of PGB was more effective in decreasing pain score than a dose of 75 mg, and a high dose (≥900 mg) of GBP reduced pain intensity than doses of 300 or 600 mg. Moreover, the incidence of adverse reactions varied with varying doses of PGB or GBP.

Conclusion

A dose-response relationship was detected in opioid consumption and postoperative pain for a single-dose preoperative administration of PGB and GBP. Making reasonable choice of drugs and dosage may prevent the occurrence of adverse reactions.

Effect of intravenous paracetamol as pre-emptive compared to preventive analgesia in a pediatric dental setting: a prospective randomized study

BACKGROUND

Efficacy of pre-emptive analgesia compared to preventive regimen, managing postoperative pain is still controversial.

AIM

Evaluating the efficacy of intravenous (IV) paracetamol as pre-emptive analgesia compared to preventive post-treatment administration in pediatric dental setting.

DESIGN

In a prospective trial, 60 noncooperative children of ASA I, II aged 3-10 years who underwent dental rehabilitation under general anesthesia were randomly divided into two groups. Pre-emptive group (n = 30) received 15 mg/kg of IV paracetamol before the start of treatment. Preventive group (n = 30) received 15 mg/kg of paracetamol at the end of treatment. Analgesic efficacy was measured by visual analog scale of faces (VASOF), percentage of children received postoperative analgesia.

RESULTS

The VASOF results in the pre-emptive group were significantly lower compared to the preventive group at 4, 8, 12, and 24 h (0.0146, 0.0188, 0.0085, and 0.0001, respectively). Less children in the pre-emptive group received supplemental fentanyl postoperatively compared to the preventive group (27.6%, 58.6%, respectively, P = 0.0170). Time to first rescue dose of fentanyl postoperatively in the pre-emptive group was later than in the preventive group (P = 0.0432).

CONCLUSIONS

Administration of IV paracetamol pre-emptively provides lower pain scores, and a decreased percentage of children required pain relief and less amount of postoperative opioids, compared to preventive administration.

Long-term weight gain and economic impact in pigs castrated under local anaesthesia

Castration is a controversial practice in swine production because in some countries is still performed without anaesthesia, and therefore causes intense suffering and stress to animals. This study investigated the effect of pre-surgical administration of local anaesthesia (LA) on the growth performance of piglets until the end of the growth phase (102 days). Piglets aged 3 to 5 days were selected in pairs of similar weights and same age. They were originated from 22 litters. The groups were randomly assigned to one of two treatments. Castration was performed with (LA; n = 45) or without (NLA; n = 45) intra-testicular administration of 0.5 mL of 2% lidocaine plus adrenaline per testicle, administered by an automatic repeating vaccinator. Castration was performed 10 min later. Average daily weight gain and economic impact were evaluated between the intervals before castration until 21 (weaning phase), before castration until 60 (end of the initial nursery phase) and before castration until 102 (growth phase) days of age. Average daily weight gain data were analyzed by comparing the average daily weight gain between the weaning phase, 60 and 102 days of age versus the initial weight (pre-castration). At the end of the growing phase, animals treated with LA showed greater weight gain than animals castrated without anaesthesia. LA also showed improved cost:benefit ratio and theore might provide greater economic benefit under the conditions used in this study. Our findings have proved that castration with LA improves long-term weight gain of piglets.

Effect of Analgesia Administration Timing on Early Post-operative Period Characteristics: A Randomized, Double-blind, Controlled Study

This study investigated the effect of time of analgesia administration in 64 patients undergoing total abdominal hysterectomy. Patients received standard general anaesthesia and were divided randomly into two equal groups. At the time of fascia closure, patients in the intra-operative (Iop) group received 0.5 mg/kg pethidine intravenously. On arrival in the post-anaesthesia care unit, the same dose of pethidine was given to patients in the post-operative (Pop) group. All patients then used a patient-controlled analgesia pump to administer pethidine analgesia as required. Times to extubation, response to verbal stimulation and orientation, post-operative pain scores and analgesic consumption were recorded. Times to extubation and response to verbal stimulation were significantly longer in the Iop group. Pain scores, analgesic consumption and additional analgesic requirements were significantly higher in the Pop group in the first 2 h post-operatively. In conclusion, intra-operative administration of pethidine provided better pain management than post-operative administration.

Design and implementation of an enhanced recovery program in thoracic surgery

Despite significant improvements in perioperative care, major surgery is still associated with major complications. Enhanced recovery after surgery was introduced by the National Health Service in the UK with the aim of improving patient outcomes and reducing length of stay in hospital. The degree of applicability differs between surgical specialties, and in thoracic surgery it has not been developed until recently. We have therefore reviewed recent literature specific to thoracic surgery, and will discuss key elements of the design, implementation and monitoring of an enhanced recovery (ER) program based on our recent experience. The program is divided into several high impact intervention measures that involve the preoperative, intraoperative and postoperative periods. Physical activity promotion and educational programs that provide information about the surgery and the surgical pathway are an essential part of the preoperative strategies. During surgery, an optimal pain control strategy, antibiotic prophylaxis and protective ventilation are important. Minimally invasive surgery and well-planned postoperative care including early drain removal and planned discharge are also important. Overall, we have shown that ER in thoracic surgery can facilitate early discharge from hospital and possibly reduce postoperative complications. Further studies are required to understand the extent of ER benefits when applied to thoracic surgery, and to test individual components in a prospective manner.

Preventive analgesia and novel strategies for the prevention of chronic post-surgical pain

Chronic post-surgical pain (CPSP) is a serious complication of major surgery that can impair a patient's quality of life. The development of CPSP is a complex process which involves biologic, psychosocial, and environmental mechanisms that have yet to be fully understood. Currently perioperative pharmacologic interventions aim to suppress and prevent sensitization with the aim of reducing pain and analgesic requirement in acute as well as long-term pain . Despite the detrimental effects of CPSP on patients, the body of literature focused on treatment strategies to reduce CPSP remains limited and continues to be understudied. This article reviews the main pharmacologic candidates for the treatment of CPSP, discusses the future of preventive analgesia, and considers novel strategies to help treat acute post-operative pain and lessen the risk that it becomes chronic. In addition, this article highlights important areas of focus for clinical practice including: multimodal management of CPSP patients, psychological modifiers of the pain experience, and the development of a Transitional Pain Service specifically designed to manage patients at high risk of developing chronic post-surgical pain.

Effect of Pre- and Postoperative Phenylbutazone and Morphine Administration on the Breathing Response to Skin Incision, Recovery Quality, Behavior, and Cardiorespiratory Variables in Horses Undergoing Fetlock Arthroscopy: A Pilot Study

This prospective blinded randomized study aimed to determine whether the timing of morphine and phenylbutazone administration affects the breathing response to skin incision, recovery quality, behavior, and cardiorespiratory variables in horses undergoing fetlock arthroscopy. Ten Standardbred horses were premedicated with acepromazine (0.04 mg kg⁻¹ IM) and romifidine (0.04 mg kg⁻¹ IV). Anesthesia was induced with diazepam (0.05 mg kg⁻¹) and ketamine (2.2 mg kg⁻¹) IV at T0. Horses in group PRE (n = 5) received morphine (0.1 mg kg⁻¹) and phenylbutazone (2.2 mg kg⁻¹) IV after induction and an equivalent amount of saline after surgery. Horses in group POST (n = 5) received the inversed treatment. Anesthesia was maintained with isoflurane 2% in 100% oxygen. Hypotension (mean arterial pressure <60 mmHg) was treated with dobutamine. All horses breathed spontaneously. Dobutamine requirements, respiratory rate (f_R), heart rate (HR), mean arterial blood pressure, end-tidal CO₂, inspired (_i) and expired (_e) tidal and minute volume (V_T and V˙E), inspiratory time (IT), and the inspiratory gas flow (V_Ti/IT) were measured every 5 min. Data were averaged during four 15 min periods before (P1 and P2) and after the incision (P3 and P4). Serial blood–gas analyses were also performed. Recoveries were unassisted, video recorded, and scored by three anesthetists blinded to the treatment. The postoperative behavior of the horses (25 demeanors), HR, and f_R were recorded at three time points before induction (T0–24 h, T0–12 h, and T0–2 h) and six time points after recovery (TR) (TR + 2, 4, 6, 12, 24, 48 h). Data were compared between groups using a Wilcoxon test and within groups using a Friedman test or a Kruskal–Wallis signed-rank test when applicable. Tidal volumes (V_Te and V_Ti) were higher in PRE than in POST during all the considered periods but the difference between groups was only significant during P2 (V_Te in mL kg⁻¹ in PRE: 13 [9, 15], in POST: 9 [8, 9], p = 0.01). None of the other variables were significantly different between and within groups. Under our experimental conditions, skin incision did not affect respiratory variables. Administration of pre- versus postoperative phenylbutazone and morphine did not influence recovery quality, HR, f_R, or animal behavior.

Assessment of preemptive analgesia efficacy in surgical extraction of third molars

BACKGROUND AND OBJECTIVES

Literature on preemptive analgesia is controversial. Reliability of results and difficult reproducibility of research contribute for non-elucidation of the subject. The aim of this study is to test the efficacy of oral ketoprofen (150 mg) preemptively administrated two days before third molar surgery, compared with postoperative administration in the same patient.

METHODS

Thirteen patients underwent surgical removal of bilateral third molar in two separate procedures. In a random and double blind procedure, oral ketoprofen 150 mg was administered every 12 hours two days before surgery and, after the procedure, the same drug was administered for three days. On the other side, a control (placebo) was used orally every 12 hours two days before surgery and, after the procedure, ketoprofen 150 mg was administered every 12 hours for three days. Postoperative pain was assessed by visual analogue scale, nominal scale, and amount of rescue analgesics consumed.

RESULTS

There was no statistically significant difference in postoperative pain between the preemptive treatment and control.

CONCLUSION

In this experimental model, preemptive analgesia was not effective in reducing postoperative pain in surgical extraction of third molar compared with the postoperative administration of the same drug.

Preventive analgesia in hip or knee arthroplasty: a systematic review

OBJECTIVE

To analyze the efficacy and safety of preventive analgesia in patients undergoing hip or knee arthroplasty due to osteoarthritis.

METHODS

A systematic literature review was performed, using a defined a sensitive strategy on Medline, Embase and Cochrane Library up to May 2013. The inclusion criteria were: patients undergoing knee and/or hip arthroplasty, adults with moderate or severe pain (≥4 on a Visual Analog Scale). The intervention, the use (efficacy and safety) of pharmacological treatment (preventive) close to surgery was recorded. Oral, topical and skin patch drugs were included. Systematic reviews, meta-analysis, controlled trials and observational studies were selected.

RESULTS

A total of 36 articles, of moderate quality, were selected. The patients included were representative of those undergoing knee and/or hip arthroplasty in Spain. They had a mean age >50 years, higher number of women, and reporting moderate to severe pain (≥4 on a Visual Analog Scale). Possurgical pain was mainly evaluated with a Visual Analog Scale. A wide variation was found as regards the drugs used in the preventive protocols, including acetaminophen, classic NSAID, Cox-2, opioids, corticosteroids, antidepressants, analgesics for neuropathic pain, as well as others, such as magnesium, ketamine, nimodipine or clonidine. In general, all of them decreased post-surgical pain without severe adverse events.

CONCLUSIONS

The use or one or more pre-surgical analgesics decreases the use of post-surgical drugs, at least for short term pain.

Preventive analgesia for postoperative pain control: a broader concept

Pain from surgical procedures occurs as a consequence of tissue trauma and may result in physical, cognitive, and emotional discomfort. Almost a century ago, researchers first described a possible relationship between intraoperative tissue damage and an intensification of acute pain and long-term postoperative pain, now referred to as central sensitization. Nociceptor activation is mediated by chemicals that are released in response to cellular or tissue damage. Pre-emptive analgesia is an important concept in understanding treatment strategies for postoperative analgesia. Pre-emptive analgesia focuses on postoperative pain control and the prevention of central sensitization and chronic neuropathic pain by providing analgesia administered preoperatively but not after surgical incision. Additional research in pre-emptive analgesia is warranted to better determine good outcome measurements and a better appreciation with regard to treatment optimization. Preventive analgesia reduces postoperative pain and consumption of analgesics, and this appears to be the most effective means of decreasing postoperative pain. Preventive analgesia, which includes multimodal preoperative and postoperative analgesic therapies, results in decreased postoperative pain and less postoperative consumption of analgesics.

Patients with chronic pain

Preoperative evaluation of patients with chronic pain is important because it may lead to multidisciplinary preoperative treatment of patients' pain and a multimodal analgesia plan for effective pain control. Preoperative multidisciplinary management of chronic pain and comorbid conditions, such as depression, anxiety, deconditioning, and opioid tolerance, can improve patient satisfaction and surgical recovery. Multimodal analgesia using pharmacologic and nonpharmacologic strategies shifts the burden of analgesia away from simply increasing opioid dosing. In more complicated chronic pain patients, multidisciplinary treatment, including pain psychology, physical therapy, judicious medication management, and minimally invasive interventions by pain specialists, can improve patients' satisfaction and surgical outcome.

Assessment of preemptive analgesia with ibuprofen coadministered or not with dexamethasone in third molar surgery: a randomized double-blind controlled clinical trial

INTRODUCTION

There is no conclusive evidence from clinical trial studies regarding preemptive analgesic interventions. Clinical trials are necessary to evaluate the efficacy of preemptive analgesic interventions already demonstrated in animal studies. Thus, it is necessary to evaluate the analgesic effect of preoperative administration of ibuprofen alone or coadministered with dexamethasone after third molar surgery.

MATERIAL AND METHODS

A randomized, double-blind, and controlled clinical trial was conducted with 94 bilateral symmetrical third molar surgeries. Preemptive analgesic medication was randomly defined: ibuprofen or placebo and ibuprofen + dexamethasone or placebo was administered to patients who served as their own control (split mouth). The variables analyzed were postoperative pain through visual analog scale (VAS), total number of rescue analgesic (TNRA), and patient satisfaction. Data were analyzed with the Mann-Whitney test.

RESULTS

There was no significant difference (p > 0.05) between ibuprofen and placebo for postoperative pain (VAS) and TNRA. Patients consumed less analgesics (TNRA) for dexamethasone + ibuprofen (p < 0.05) and felt more comfortable in the postoperative period after surgery (p < 0.05).

DISCUSSION

The preemptive analgesia with ibuprofen was insufficient to inhibit central sensitization, whereas its association with dexamethasone was more effective in preventing pain in third molar surgery.

Surgically induced neuropathic pain: understanding the perioperative process

Nerve damage takes place during surgery. As a consequence, significant numbers (10%-40%) of patients experience chronic neuropathic pain termed surgically induced neuropathic pain (SNPP). The initiating surgery and nerve damage set off a cascade of events that includes both pain and an inflammatory response, resulting in "peripheral and central sensitization," with the latter resulting from repeated barrages of neural activity from nociceptors. In affected patients, these initial events produce chemical, structural, and functional changes in the peripheral and central nervous systems (CNS). The maladaptive changes in damaged nerves lead to peripheral manifestations of the neuropathic state-allodynia, sensory loss, shooting pains, etc, that can manifest long after the effects of the surgical injury have resolved. The CNS manifestations that occur are termed "centralization of pain" and affect sensory, emotional, and other (eg, cognitive) systems as well as contributing to some of the manifestations of the chronic pain syndrome (eg, depression). Currently there are no objective measures of nociception and pain in the perioperative period. As such, intermittent or continuous pain may take place during and after surgery. New technologies including direct measures of specific brain function of nociception and new insights into preoperative evaluation of patients including genetic predisposition, appear to provide initial opportunities for decreasing the burden of SNPP, until treatments with high efficacy and low adverse effects that either prevent or treat pain are discovered.

Multimodal therapies for postoperative nausea and vomiting, and pain

Postoperative nausea and vomiting (PONV) and pain are two of the major concerns for patients presenting for surgery. The causes of PONV are multifactorial and can largely be categorized as patient risk factors, anaesthetic technique, and surgical procedure. Antiemetics work on several different receptor sites to prevent or treat PONV. This is probably why numerous studies have now demonstrated that using more than one antiemetic is usually more effective and results in fewer side-effects than simply increasing the dose of a single antiemetic. A multimodal approach to PONV should not be limited to drug therapy alone but should involve a holistic approach starting before operation and continuing intraoperatively with risk reduction strategies to which are added prophylactic antiemetics according to the assessed patient risk for PONV. With the increasing understanding of the pathophysiology of acute pain, especially the occurrence of peripheral and central hypersensitization, it is unlikely that a single drug or intervention is sufficiently broad in its action to be adequately effective, especially with moderate or greater pain. Although morphine and its congeners are usually the foundation of pain management regimens, as their dose increases so does the incidence of side-effects. Thus, the approach for the management of acute postoperative pain is to use multiple drugs or modalities (e.g. regional anaesthesia) to maximize pain relief and reduce side-effects.

[Review: effect of preventive analgesia on postoperative pain]

Preventive analgesia (administration of a technique or analgesic drug with the aim of reducing postoperative pain, hyperalgesia and allodynia) has shown to be effective in experimental studies. However, the results in patients have been controversial. A review has been made of the clinical trials published during the last 5 years to test the efficacy of preventive analgesia on postoperative pain. A search was made of the published literature in Medline, with the terms "pre-emptive analgesia", "preventive analgesia" and "postoperative pain", selecting prospective, controlled, randomised and double blind studies that compared analgesic regimens before and after the incision or the same or very similar postoperative conditions. A total of 27 studies were found during the period 2005-2010 that complied with the inclusion criteria. Analgesia measurement variables were analysed, such as postoperative pain, time passed until the first rescue, and total analgesic requirements. Preventive analgesia was effective in 15 of the 27 studies, with pre-incisional epidural drug administration being the most effective (local anaesthetics with or without opioids, clonidine). The possible effectiveness of preventive analgesia in humans is still controversial, partly due to the wide heterogeneity in the inclusion criteria, types of patients, or the analgesia measurement parameters analysed by the studies. More studies are required with common criteria and objectives.

Comparison of pre-emptive ibuprofen, paracetamol, and placebo administration in reducing post-operative pain in primary tooth extraction

BACKGROUND

This study investigates preliminary investigations that a pre-emptive analgesia administration may reduce post-extraction pain.

AIM

This prospective, placebo-controlled, randomized, double-blind trial was planned to compare the efficacy of the pre-emptive administration of ibuprofen, paracetamol, and placebo in reducing post-extraction pain in children.

DESIGN

Forty-five children, ages 6-12, who needed primary mandibular molar tooth extraction were treated in paediatric dental clinics, with treatment preceded by local anaesthesia and analgesic drugs during the preoperative period. A five-face scale was used to evaluate pain reaction during the injection, extraction, and post-operative period. Self-report scores were recorded when the local anaesthesia had been administered in soft tissues and both before and after the extraction was completed. The Kruskal-Wallis and Mann-Whitney U tests (with Bonferroni correction paired t-test as the post hoc test) were used at a confidence level of 95%.

RESULTS

The use of pre-emptive analgesics showed lower scores compared to the placebo, irrespective of the age, weight, gender of the child, and the number of teeth extracted during the study period. Additionally, ibuprofen exhibited lower pain scores (P < 0.05) compared to paracetamol at the 15-min (P < 0.001) and 4-h (P < 0.009) periods.

CONCLUSIONS

Preoperative use of ibuprofen and paracetamol may provide a pre-emptive analgesic effect in paediatric patients who receive adequate analgesia during mandibular primary tooth extraction.

Pre-emptive analgesia for postoperative pain control: a review

Pain can play an important role at the social and psychological level; hence one of the major goals of anaesthesia is to control and reduce the incidence of postoperative pain. The use of an analgesia before surgical incision may offer one of the most innovative and promising strategies for better pain control throughout the perioperative period. Pre-emptive analgesia refers to pharmacological intervention initiated prior to a painful stimulus in order to inhibit nociceptive mechanisms before they are triggered. Pre-emptive analgesia has three objectives: to reduce pain resulting from the activation of inflammatory mechanisms triggered by surgical incision; to hinder the pain memory response of the central nervous system; and to ensure a good control of postoperative pain in order to avoid the development of chronic pain. The following provides an overview of the scientific rationale for pre-emptive analgesia alongside an overview of published systematic reviews and randomized clinical trials related to this topic.

The influence of pre-emptive analgesia on postoperative analgesia and its objective evaluation

INTRODUCTION

The evaluation of pain intensity is still a subject of research. Mostly psychological evaluations are used. We started to conduct biochemical evaluation in animal experiments. Now we present biochemical evaluation in postoperative pain in man.

MATERIAL AND METHODS

In 67 patients herniotomy was done. For pre-emptive analgesia morphine and pethidine were used and the following indicators were measured: visual analogue scale (VAS), measurement of lipid spectra, saccharides and proteins, thioredoxin, super-oxide dismutase (SOD), glutathione peroxidase (GPx) and NAD(P)H-oxidase (NOX), and free radicals using electron paramagnetic resonance (EPR). Blood samples were taken and tested: before pre-medication and intervention, 4 h after and 24 h after intervention.

RESULTS

Free radicals (FR) increased in individual samples during the postoperative course in pethidine and without pre-medication. After application of morphine the FR were insignificantly reduced. Statistically significant differences were found in albumin, prealbumin, apolipoprotein A, total cholesterol, atherosclerotic index, CRP, glucose, and thioredoxin (p ≤ 0.001). A greater difference was seen in VAS values between morphine and pethidine premedications (p ≤ 0.001).

CONCLUSIONS

It was proved that the biochemical markers of lipid, protein and saccharide metabolisms and free radicals as well as singlet oxygen can serve as very good indicators of the intensity of pain and nociception. In patients it was proved that pre-emptive analgesia plays an important role in reducing the intensity of postoperative pain. From the three modalities of pre-emptive analgesia morphine represents the best solution.

Intraoperative Nitrous Oxide as a Preventive Analgesic

Preventive analgesia is defined as the persistence of the analgesic effects of a drug beyond the clinical activity of the drug. The N-methyl D-aspartate receptor plays a critical role in the sensitisation of pain pathways induced by injury. Nitrous oxide inhibits excitatory N-methyl D-aspartate sensitive glutamate receptors. The objective of our study was to test the efficacy of nitrous oxide as a preventive analgesic. We conducted a retrospective analysis of data from a subset of patients (n=100) randomly selected from a previous major multicentre randomised controlled trial on nitrous oxide (ENIGMA trial). Data analysed included postoperative analgesic requirements, pain scores and duration of patient-controlled analgesia during the first 72 postoperative hours. There was no significant difference in postoperative oral morphine equivalent usage (nitrous group 248 mg, no nitrous group 289 mg, mean difference -43 mg, 95% confidence interval 141 to 54 mg). However, patients who received nitrous oxide had a shorter duration of patient-controlled analgesia use (nitrous group 35 hours, no nitrous group 51 hours, mean difference -16 hours, 95% confidence interval -29 to -2 hours, P=0.022). There was no difference in pain scores between the groups. The shorter patient-controlled analgesia duration in the nitrous oxide group suggests that intraoperative nitrous oxide may have a preventive analgesic effect.

Skin incision induces expression of axonal regeneration-related genes in adult rat spinal sensory neurons

Skin incision and nerve injury both induce painful conditions. Incisional and postsurgical pain is believed to arise primarily from inflammation of tissue and the subsequent sensitization of peripheral and central neurons. The role of axonal regeneration-related processes in development of pain has only been considered when there has been injury to the peripheral nerve itself, even though tissue damage likely induces injury of resident axons. We sought to determine if skin incision would affect expression of regeneration-related genes such as activating transcription factor 3 (ATF3) in dorsal root ganglion (DRG) neurons. ATF3 is absent from DRG neurons of the normal adult rodent, but is induced by injury of peripheral nerves and modulates the regenerative capacity of axons. Image analysis of immunolabeled DRG sections revealed that skin incision led to an increase in the number of DRG neurons expressing ATF3. RT-PCR indicated that other regeneration-associated genes (galanin, GAP-43, Gadd45a) were also increased, further suggesting an injury-like response in DRG neurons. Our finding that injury of skin can induce expression of neuronal injury/regeneration-associated genes may impact how clinical postsurgical pain is investigated and treated.

PERSPECTIVE

Tissue injury, even without direct nerve injury, may induce a state of enhanced growth capacity in sensory neurons. Axonal regeneration-associated processes should be considered alongside nerve signal conduction and inflammatory/sensitization processes as possible mechanisms contributing to pain, particularly the transition from acute to chronic pain.

Hindpaw incision in early life increases the hyperalgesic response to repeat surgical injury: critical period and dependence on initial afferent activity

Pain in early life can enhance the response to subsequent injury, but effects are influenced by both the nature and timing of neonatal injury. Using plantar hindpaw incision, we investigated how postnatal age influences the response to repeat surgical injury two weeks later. The degree and time course of behavioural changes in mechanical withdrawal threshold were measured, and injury-related hyperalgesia was further quantified by flexion reflex electromyographic responses to suprathreshold mechanical stimuli 24 h following incision. Plantar hindpaw incision produces acute mechanical hyperalgesia in neonatal and adult rats, but incision in neonatal pups has an additional effect on the response to subsequent injury. With initial incision at postnatal day (P) 3 or 6, the degree of hyperalgesia following repeat incision 2 weeks later was greater than in animals having a single incision at the same age. At older ages (initial incision at P10, P21 or P40) responses did not differ in repeat and single incision groups. To test the role of primary afferent activity, levobupivacaine sciatic block was performed prior to P6 plantar incision, and controls received saline or subcutaneous levobupivacaine. Repeat peri-operative, but not a single pre-operative sciatic block, prevented the enhanced response to repeat incision two weeks later. Our results show that the first postnatal week represents a critical period when incision increases hyperalgesia following repeat surgery two weeks later, and effects are initiated by peripheral afferent activity. This has potential therapeutic implications for the type and duration of peri-operative analgesia used for neonatal surgery.

Adding gabapentin to a multimodal regimen does not reduce acute pain, opioid consumption or chronic pain after total hip arthroplasty

BACKGROUND

Gabapentin (GPN) is effective in reducing post-operative pain and opioid consumption, but its effects with regional anesthesia for total hip arthroplasty (THA) are not known. We designed this study to determine whether (1) gabapentin administration reduces pain and opioid use after THA using a multimodal analgesic regimen including spinal anesthesia; (2) pre-operative administration of gabapentin is more effective than post-operative administration.

METHODS

After REB approval and informed consent, 126 patients were enrolled in a double-blinded, randomized-controlled study. Patients received acetaminophen 1 g per os (p.o.), celecoxib 400 mg p.o. and dexamethasone 8 mg intravenously, 1-2 h pre-operatively. Patients were randomly assigned to one of three treatment groups (G1: Placebo/Placebo; G2: GPN/Placebo; G3: Placebo/GPN). Patients received gabapentin 600 mg (G2) or placebo (G1 and G3) 2 h before surgery. All patients had spinal anesthesia [15 mg (3cc) of 0.5% hypobaric bupivacaine with 10 microg of fentanyl]. In the post-anesthetic care unit, patients received gabapentin 600 mg (G3) or placebo (G1 and G2). On the ward, patients received acetaminophen 1000 mg p.o. q6h, celecoxib 200 mg p.o. q12h and a morphine PCA device. Patients were interviewed 6 months post-surgery to determine the incidence and severity of chronic post-surgical pain.

RESULTS

Mean+/-SD cumulative morphine (mg) consumption (G1=49.4+/-24.8, G2=47.2+/-30.1 and G3=56.1+/-38.2) at 48 h and pain scores at 12, 24, 36 and 48 h post-surgery were not significantly different among the groups [G1 (n=38), G2 (n=38) and G3 (n=38)]. Side effect profiles were similar across groups. Six months after surgery, the number of patients who reported chronic post-surgical pain (G1=10, G2=12 and G3=9) and the severity of the pain (G1=4.2+/-2.9, G2=4.1+/-2.2 and G3=4.9+/-2.2) did not differ significantly among the groups (P>0.05).

CONCLUSIONS

A single 600 mg dose of gabapentin given pre-operatively or post-operatively does not reduce morphine consumption or pain scores in hospital or at 6 months after hip arthroplasty within the context of spinal anesthesia and a robust multimodal analgesia regimen.

Transition from acute to chronic postsurgical pain: risk factors and protective factors

Most patients who undergo surgery recover uneventfully and resume their normal daily activities within weeks. Nevertheless, chronic postsurgical pain develops in an alarming proportion of patients. The prevailing approach of focusing on established chronic pain implicitly assumes that information generated during the acute injury phase is not important to the subsequent development of chronic pain. However, a rarely appreciated fact is that every chronic pain was once acute. Here, we argue that a focus on the transition from acute to chronic pain may reveal important cues that will help us to predict who will go on to develop chronic pain and who will not. Unlike other injuries, surgery presents a unique set of circumstances in which the precise timing of the physical insult and ensuing pain are known in advance. This provides an opportunity, before surgery, to identify the risk factors and protective factors that predict the course of recovery. In this paper, the epidemiology of chronic postsurgical pain is reviewed. The surgical, psychosocial, socio-environmental and patient-related factors that appear to confer a greater risk of developing chronic postsurgical pain are described. The genetics of chronic postsurgical pain are discussed with emphasis on known polymorphisms in human genes associated with chronic pain, genetic studies of rodent models of pain involving surgical approaches, the importance of developing accurate human chronic postsurgical pain phenotypes and the expected gains for chronic postsurgical pain medicine in the post-genomic era. Evidence is then reviewed for a preventive multimodal analgesic approach to surgery. While there is some evidence that chronic postsurgical pain can be minimized or prevented by an analgesic approach involving aggressive perioperative multimodal treatment, other studies fail to show this benefit. The transition of acute postoperative pain to chronic postsurgical pain is a complex and poorly understood developmental process, involving biological, psychological and social-environmental factors.

Use of a lidocaine patch in the management of postsurgical neuropathic pain in patients with cancer: a phase III double-blind crossover study (N01CB)

OBJECTIVE

Current therapies often have limited efficacy and untenable side effects when used to treat persistent incisional pain following cancer-related surgery. Lidocaine patches reduce neuropathic pain from herpes zoster but their benefits for persistent cancer-related postsurgical incisional pain remain unclear.

STUDY DESIGN

Multicenter, double-blind, randomized, two-period crossover trial.

MATERIALS AND METHODS

Twenty-eight cancer patients with postsurgical incisional pain were randomly assigned to receive either lidocaine patches followed by placebo patches or the reverse. Each study period lasted 4 weeks. Patches were applied daily upon waking and left in place for a maximum of 18 h. The primary outcome measure, an 11-point pain intensity rating scale, was administered weekly. Secondary outcomes were administered weekly (Brief Pain Inventory-Short Form(BPI-SF), Subject Global Impression of Change) and at the end of each study period (Short Form-Magill Pain Questionnaire, Linear Analogue Self Assessment Scale, Neuropathy Pain Scale, Pain Catastrophizing Scale, Profile of Mood States Short Form).

RESULTS

Twenty-one patients completed the first period and 18 completed their crossover second phase. No significant intergroup differences were detected in pain intensity ratings. Few secondary end points were significantly different when subjects used the lidocaine versus placebo patches. BPI-SF interference scores were lower in patients using the lidocaine patch during the first study period, including several scores that achieved statistical significance, general activity (p = 0.02), work (p = 0.04), and relations with others (p = 0.02).

CONCLUSION

Lidocaine patch use did not significantly reduce pain intensity ratings or the majority of related secondary end points in cancer patients with persistent incisional pain.