Involvement of presurgical pain in preemptive analgesia for orthopedic surgery: a randomized double blind study

The Effect of Central Sensitization on Postoperative Neurocognitive Dysfunction in Hospitalized Elderly Patients: A Prospective Cohort Clinical Trial

OBJECTIVE

To investigate whether central sensitization (CS) in elderly patients was a predictive risk factor for postoperative neurocognitive dysfunction (PNCD).

METHODS

One hundred and thirty-three aged patients undergoing total knee arthroplasty (TKA) who received femoral nerve block and general anesthesia were recruited in this research and prospectively assigned into two groups according to the Central Sensitization Inventory (CSI) score: group C (n = 106, CSI score less than 40) and group CS (n = 27, CSI score higher than 40). Scores of Montreal Cognitive Assessment (MoCA), Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Numerical Rating Scale (NRS) and Quality of recovery-40 (QoR-40) questionnaires were assessed. Basic information and clinical records of all participants were also collected.

RESULTS

PNCD occurred in 24 (22.6%) of patients in group C and 16 (59.3%) in group CS (p < .05). Multivariate logistic regression analysis revealed that patients with CSI score ≥40 before surgery exhibited higher risk of PNCD after adjustment for other risk factors (p < .05). Compared to group C, the pre- and post-operative NRS scores, pain duration, the WOMAC score, and propofol consumptions for anesthesia induction were significantly increased in group CS (p < .05).

CONCLUSION

Hospitalized elderly patients with clinical symptoms of CS scores may have increased risk of PNCD following TKA.

Predictors of postoperative pain using PROMIS pain interference two-years following knee surgery

Introduction

The purpose of this study was to identify preoperative factors associated with worse PROMIS Pain Interference (PI) two years following knee surgery.

Methods

Participants completed surveys preoperatively and two years postoperatively. Data collected included demographics, medical history, and multiple patient-reported outcomes measures, including PROMIS PI.

Results

After controlling for confounders, lower income, smoking, worse PROMIS Anxiety, worse Numeric Pain Score body pain, and worse Marx Activity Rating Scale were independent predictors for worse PROMIS PI two years after surgery.

Conclusion

Worse PROMIS PI two years after elective knee surgery is associated with multiple socio-demographic patient identifiers.

Postoperative Pain After Surgical Treatment of Ankle Fractures: A Prospective Study

Background:

Postoperative pain after fixation of ankle fractures has a substantial effect on surgical outcome and patient satisfaction. Patients requiring large amounts of narcotics are at higher risk of long-term use of pain medications. Few prospective studies investigate patient pain experience in the management of ankle fractures.

Methods:

We prospectively evaluated the pain experience in 63 patients undergoing open reduction and internal fixation of ankle. The Short-Form McGill Pain Questionnaire was administered preoperatively and postoperatively (PP) at 3 days (3dPP) and 6 weeks (6wPP). Anticipated postoperative pain (APP) was recorded.

Results:

No significant differences were found between PP, APP, and 3dPP; however, 6wPP was markedly lower. Significant correlations were found between PP and APP and between preoperative and postoperative Short-Form McGill Pain Questionnaire scores. PP and APP were independent predictors of 3dPP; however, only APP was predictive of 6wPP. Sex, age, and inpatient versus outpatient status were not notable factors. No statistically significant differences were found in pain scores between fracture types.

Conclusions:

Both preoperative pain severity and anticipated postoperative pain are predictive of postoperative pain levels. Orthopaedic surgeons should place a greater focus on the postoperative management of patient pain and expectations after surgical procedures.

Effect of Preoperative Oral Amantadine on Acute and Chronic Postoperative Pain After Mandibular Fracture Surgery

BACKGROUND

Postoperative pain from open reduction and internal fixation of mandibular fracture is a serious issue. Amantadine is an N-methyl-D-aspartic acid or N-methyl-D-aspartate (NMDA) receptor antagonist that can be effective against postoperative pain.

OBJECTIVES

The present study examined the efficacy of amantadine in alleviating the postoperative pain of mandibular fracture surgery.

PATIENTS AND METHODS

In this double-blind study, 60 patients (ASA physical status I-II) were randomly divided into two groups. The mean ages of the participants were 31.2 ± 13.1 years and 32.3 ± 18.1 years, respectively. The male/female ratios were 24/6 and 26/4, respectively, in the case and control groups. Randomization was based on a single sequence of random assignments using computer-generated random numbers. Group I was given oral amantadine 100 mg 1 hour before surgery, and group II received a placebo at the identical time. Through PCA pumps, patients received a bolus dose of morphine at 0.02 mg/kg body weight, to a maximum of 1.5 mg. PCA pumps were set at 6 minutes lockout intervals and a maximum dose of 0.15 mg/kg/h, to a maximum of 10 mg/h. Pain was assessed using a visual analog scale (VAS) at 0, 2, 4, 6, 12, and 24 hours and 1, 2, 3, 4, 5, and 6 months after surgery. The amounts of analgesic consumed were recorded for the first 24 hours, and for 6 months after surgery.

RESULTS

There were no significant differences between the two groups with respect to age, gender, nausea and vomiting, sleep quality, blood pressure, and heart rate. No significant differences were observed between the two groups in pain scores (P = 0.39) and analgesic consumption (P = 0.78).

CONCLUSIONS

The results suggest that a single dose of preoperative oral amantadine did not reduce acute or chronic postoperative pain, nor analgesic consumption.

Randomized controlled trial on preemptive analgesia for acute postoperative pain management in children

BACKGROUND

Preemptive analgesia is an anti-nociceptive treatment that starts before surgery and prevents the establishment of central sensitization. Whether preemptive analgesia is more effective than conventional regimens for managing postoperative pain remains controversial. This study evaluated the efficacy of intravenous preemptive analgesia for acute postoperative pain control in pediatric patients.

METHODS

In this prospective randomized controlled trial, 51 children aged 3-7 years, scheduled for corrective osteotomy were randomized into control (group C) or preemptive (group P) group. Both groups received standardized general anesthesia, including intravenous patient-controlled analgesia (IV-PCA) with fentanyl, which was started before skin incision in group P or 5 min thereafter in group C. IV-PCA data, pain scores using verbal rating scale (VRS) and Wong-Baker FACES(®) pain rating scale (WBFS), emergence agitation score (EAS) using the Pediatric Anesthesia Emergence Delirium (PAED) scale, analgesic requirements, and complications were recorded.

RESULTS

The primary outcome, pain score at postoperative 1 h, showed no difference between the groups. Both groups did not demonstrate emergence agitation (PAED cutoff value ≥ 12), although the EAS at admission to the postanesthetic care unit (PACU) was lower in group P than in group C (P = 0.002; mean difference 4.85, 95% CI 1.97-7.73). There were no differences in the delivered volume of IV-PCA, frequency of pushing the IV-PCA button, effective push attempts, VRS, WBFS, EAS at discharge from the PACU, additional analgesic requirements, and complications.

CONCLUSION

Preemptive analgesia using IV-PCA with fentanyl showed no significant advantages for postoperative analgesia after corrective osteotomy in pediatric patients.

Postoperative pain associated with orthopedic shoulder and elbow surgery: a prospective study

BACKGROUND

In the last 2 decades, extensive research in postoperative pain management has been undertaken to decrease morbidity. Orthopedic procedures tend to have increased pain compared with other procedures, but further research must be done to manage pain more efficiently. Postoperative pain morbidities and analgesic dependence continue to adversely affect health care.

MATERIALS AND METHODS

The study assessed the pain of 78 elbow and shoulder surgery patients preoperatively and postoperatively using the Short-Form McGill Pain Questionnaire (SF-MPQ). Preoperatively, each patient scored their preoperative pain (PP) and anticipated postoperative pain (APP). Postoperatively, they scored their 3-day (3dpp) and 6-week postoperative pain (6wpp). The pain intensities at these 4 intervals were then compared and analyzed using Pearson coefficients.

RESULTS

APP and PP were strong predictors of postoperative pain. The average APP was higher than the average postoperative pain. The 6wpp was significantly lower than the 3dpp. Sex, chronicity, and type of surgery were not significant factors; however, the group aged 18 to 39 years had a significant correlation with postoperative pain.

CONCLUSION

PP and APP were both independent predictors of increased postoperative pain. PP was also predictive of APP. Although, overall postoperative pain was lower than APP or PP due to pain management techniques, postoperative pain was still significantly higher in patients with increased APP or PP than their counterparts. Therefore, surgeons should factor patient's APP and PP to better manage their patient's postoperative pain to decrease comorbidities.

Opioids and central sensitisation: I. Pre-emptive analgesia

Opioids are powerful analgesics when used to treat acute pain and some forms of chronic pain. A large body of literature has shown that opioids can, in addition, also prevent (this review) or induce and perhaps reverse, some forms central sensitisation in in vitro and in vivo animal models of pain. However, the concept of central sensitisation is, at present, ambiguous and the usefulness of opioids as preemptive analgesics in human pain patients is still not clear.

Efficacy of augmenting a subacromial continuous-infusion pump with a preoperative interscalene block in outpatient arthroscopic shoulder surgery: a prospective, randomized, blinded, and placebo-controlled study

PURPOSE

This study's purpose was to determine the effectiveness of adding a preoperative interscalene brachial plexus block to standard postoperative management, including oral narcotics and a subacromial bupivacaine infusion pump, after arthroscopic shoulder surgery.

METHODS

After performing a prospective power analysis and obtaining institutional board approval, we conducted a randomized placebo-controlled trial of 53 patients separated into a preoperative interscalene brachial plexus group and a control group. Group 1 received an interscalene block with 30 mL of 0.5% ropivacaine. Group 2 received a placebo with 10 mL of saline solution. All patients postoperatively received an arthroscopically placed subacromial infusion pump catheter for 72 hours and oral narcotics. Pain scores on a visual analog scale (VAS) and narcotic pill use were recorded at 6, 12, 20, 32, 40, 52, 60, 72, and 80 hours.

RESULTS

Preoperative pain scores between groups were not significant (P > .05). A statistically significant difference was found for decreased pain scores at 6 hours after discharge in patients receiving an interscalene block (P = .001) (VAS of 30.9 in group 1 v 61.8 in group 2). There was also a decrease in the number of narcotic pills taken at the 6-hour time interval (P = .1) (0.6 pills v 1.1 pills). Group 1 had a rebound phenomenon 20 hours after discharge. Pain scores spiked as the effects of the block wore off (P = .08) (net change in VAS score increase, 25.0 v 10.3). No other statistical or clinical differences were observed.

CONCLUSIONS

The addition of a preoperative interscalene block to a postoperative subacromial infusion pump provided significant improvement of pain control only at 6 hours after discharge. Twelve hours after discharge, this benefit had disappeared. A rebound phenomenon of increased pain at 20 hours was seen after the interscalene block had worn off. After 20 hours, no statistically significant or clinically applicable differences were found.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

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.

Postoperative pain following foot and ankle surgery: a prospective study

BACKGROUND

Orthopaedic procedures have been reported to have the highest incidence of pain compared to other types of operations. There are limited studies in the literature that investigate postoperative pain.

MATERIALS AND METHODS

A prospective study of 98 patients undergoing orthopedic foot and ankle operations was undertaken to evaluate their pain experience. A Short-Form McGill Pain Questionnaire (SF-MPQ) was administered preoperatively and postoperatively.

RESULTS

The results showed that patients who experienced pain before the operation anticipated feeling higher pain intensity immediately postoperatively. Patients, on average, experienced higher pain intensity 3 days after the operation than anticipated. The postoperative pain intensity at 3 days was the most severe, while postoperative pain intensity at 6 weeks was the least severe. Age, gender and preoperative diagnosis (acute versus chronic) did not have a significant effect on the severity of pain that patients experienced. Six weeks following the operation, the majority of patients felt no pain. In addition, the severity of preoperative pain was highly predictive of their anticipated postoperative pain and 6-week postoperative pain, and both preoperative pain and anticipated pain predict higher immediate postoperative pain.

CONCLUSION

The intensity of patients' preoperative pain was predictive of the anticipated postoperative pain. Patients' preoperative pain and anticipated postoperative pain were independently predictive of the 3-day postoperative pain. The higher pain intensity a patient experienced preoperatively suggested that their postoperative pain severity would be greater. Therefore, surgeons should be aware of these findings when treating postoperative pain after orthopaedic foot and ankle operations.

[Pain therapy after spinal surgery]

A dorsal approach during spinal surgery offers the possibility to distribute drugs directly to the nerve root or epidurally. This can be done via a single intraoperative dose or by placing an epidural catheter. A safe and effective analgesia can thereby be achieved. As placement is done under visual control, no major complications are to be expected. In nerve root compressions, additional local application of steroids and preoperative gabapentin seems sensible. No advantage of preemptive administration of other analgesics can be determined. Another problem, especially of ventral fusions, is the commonly needed autologous pelvic bone grafts. Here the local application of local anesthetics or opioids makes sense. In transthoracic approaches epidural analgesia is recommended by thoracic surgeons, but this is difficult to perform especially in children with deformities. Furthermore it is generally important not to compromise neuralgic controls by analgesic measures.

[A multimodal and multidisciplinary postoperative pain management concept]

Under-treatment of acute postoperative pain can lead to chronic pain with neuronal plasticity and result in poor surgical outcomes. A multimodal approach is therefore necessary to reduce postoperative pain by combining various analgesics with a non-pharmacological strategy. The current use of multimodal approaches, even for the management of postoperative pain, can reduce the side effects of pharmaceutical therapy alone as well as reducing the length of hospital stay. Adequate pain control is an important prerequisite for the application of rehabilitation programmes and will thereby influence functional outcome. In addition, patient satisfaction, as a major benchmarking factor after surgical treatment, is significantly influenced by the quality of postoperative pain management.

The science of minimally invasive total hip arthroplasty

Minimally invasive hip surgery has stimulated a new process in hip arthroplasty. There is consensus among surgeons about the benefits of anesthesia, pain management, and rapid recovery protocols. The benefits of the surgical technique for small incision surgery remain controversial. Some patients influence this controversy because they prefer minimally invasive hip surgery: they associate less body violation and better cosmesis with smaller incisions. Small incision surgery is associated with a learning curve and requires specialized instruments for favorable outcomes. Despite being a more difficult operation to perform, in skilled hands it is a safe procedure that does not increase complication rates as shown by recent prospective, randomized studies. Correct component positioning has been achieved consistently with these procedures and short-term results of small incision surgery are the same as with long incisions. New anesthesia and pain management techniques have led to remarkable early functional results, making same-day surgery possible. With improved instrumentation such as computer navigation, minimally invasive total hip arthroplasty will become more prevalent.

Genetic susceptibility and development of chronic non-malignant back pain

Previous data indicate that persistent pain states often involve sensitization within the central nervous system (CNS). Many recently described human genetic variants may affect these central processes. Genetic variability influences both synthesis and function of proteins affecting the plasticity of the CNS. Hence, individual genetic variability may be important to understand the development of many persistent pain conditions including chronic nonmalignant back pain. In this review we argue that genotyping of each patient may be a valuable complement to diagnosis of back disorders. This may be important for future prescription of medicine to individuals predisposed for persistent pain. Increased understanding of genetic variability may also improve multidisciplinary and cognitive-behavioral approaches to management of persistent pain. Translation of this information from the laboratory into clinical application will be important for future prevention as well as treatment of long-lasting non-malignant pain conditions.

The efficacy of preemptive analgesia for acute postoperative pain management: a meta-analysis

Whether preemptive analgesic interventions are more effective than conventional regimens in managing acute postoperative pain remains controversial. We systematically searched for randomized controlled trials that specifically compared preoperative analgesic interventions with similar postoperative analgesic interventions via the same route. The retrieved reports were stratified according to five types of analgesic interventions: epidural analgesia, local anesthetic wound infiltration, systemic N-methyl-d-aspartic acid (NMDA) receptor antagonists, systemic nonsteroidal antiinflammatory drugs (NSAIDs), and systemic opioids. The primary outcome measures analyzed were the pain intensity scores, supplemental analgesic consumption, and time to first analgesic consumption. Sixty-six studies with data from 3261 patients were analyzed. Data were combined by using a fixed-effect model, and the effect size index (ES) used was the standardized mean difference. When the data from all three outcome measures were combined, the ES was most pronounced for preemptive administration of epidural analgesia (ES, 0.38; 95% confidence interval [CI], 0.28-0.47), local anesthetic wound infiltration (ES, 0.29; 95% CI, 0.17-0.40), and NSAID administration (ES, 0.39; 95% CI, 0.27-0.48). Whereas preemptive epidural analgesia resulted in consistent improvements in all three outcome variables, preemptive local anesthetic wound infiltration and NSAID administration improved analgesic consumption and time to first rescue analgesic request, but not postoperative pain scores. The least proof of efficacy was found in the case of systemic NMDA antagonist (ES, 0.09; 95% CI, -0.03 to 0.22) and opioid (ES, -0.10; 95% CI, -0.26 to 0.07) administration, and the results remain equivocal.

Pre- and intraoperative epidural ropivacaine have no early preemptive analgesic effect in major gynecological tumour surgery

PURPOSE

Thoracic epidural analgesia (TEA) is an established technique for postoperative pain relief after major abdominal surgery. However it is still under discussion whether pre-incisional TEA can reduce postoperative pain perception or postoperative analgesic consumption.

METHODS

The present prospective, randomized, double-blind study was performed to investigate the effects of intra- and postoperative TEA vs only postoperative TEA using ropivacaine 0.375% in 30 women scheduled for major abdominal tumour surgery. Prior to induction of general anesthesia patients received an epidural bolus of 10 mL saline in Group I (GI) and 10 mL ropivacaine 0.375% in Group II (GII) followed by an infusion of 6 mL x hr(-1) of the respective solution during surgery. Postoperatively all patients received an epidural infusion of 6 mL x hr(-1) ropivacaine 0.375% during 24 hr followed by patient controlled epidural analgesia for the next 72 hr. Operative data, dynamic pain scores, consumption of local anesthetics and standardized supplemental analgesics were analyzed.

RESULTS

No difference was seen between groups with respect to the amount of required postoperative local anesthetics and supplemental analgesics, pain scores and side effects during the first 96 hr following surgery except a reduction of intraoperative sufentanil consumption (GI: 143.2 +/- 52.6 vs GII: 73.3 +/- 32.6 microg, P < 0.001).

CONCLUSION

Intraoperative TEA with ropivacaine 0.375% did not significantly reduce the amount of analgesics required after major abdominal gynecological tumour surgery.

Systemic, but not pulmonary, hemodynamics are depressed during combined high thoraco-cervical epidural and general anesthesia in dogs

PURPOSE

An epidural block is frequently combined with general anesthesia. Both systemic and pulmonary hemodynamics may be affected by high epidural anesthesia and the combined general anesthetic. These effects were investigated in a canine model.

METHODS

Systemic and pulmonary hemodynamics during a combined high thoraco-cervical epidural and general anesthesia were studied in dogs; the animals were anesthetized with propofol, 10 mg.kg(-1).hr(-1), or 2% sevoflurane, and then 1% mepivacaine, 5 mL, was injected epidurally between T1 and T2. Cardiac output (CO), pulmonary capillary wedge pressure (PCWP), pulmonary arterial pressure (PAP), mean arterial pressure (MAP), central venous pressure (CVP), electrocardiogram, and arterial and mixed venous gases were monitored for over 90 min after epidural mepivacaine. The interval between sevoflurane and propofol studies was two hours.

RESULTS

Baseline measurement of MAP with sevoflurane anesthesia was significantly lower (P < 0.05-0.01) at every time point than with propofol anesthesia. After epidural mepivacaine (C1)-T7/8 blockade), MAP (P < 0.05-0.01), CO (P < 0.05-0.01), and heart rate (P < 0.05-0.01) decreased significantly during both propofol and sevoflurane anesthesia. In the sevoflurane group, stroke volume decreased significantly (P < 0.05-0.01) but recovered; however, MAP (P < 0.01) and CO (P < 0.05) did not recover 90 min after the injection. Mean CVP and systemic vascular resistance were not altered. There were no changes in mean PAP, mean PCWP, and pulmonary vascular resistance.

CONCLUSION

A combined high thoracic/general anesthesia depressed systemic hemodynamics, whereas the pulmonary circulation was not affected. The extent of the depression varied with the general anesthetics used, sevoflurane and propofol.

Preemptive analgesia in foot and ankle surgery

Central neuroplasticity, or changes in CNS processing due to surgical nociception. can amplify postoperative pain. As a result, a hyperalgesic state called wind-up can occur, having debilitating effects on postoperative patients. Preemptive analgesia works to prevent this process and results in a more positive surgical experience. Inhibition of afferent pain pathways by use of local anesthetic blocks, altered perception of pain with opioid use, and inhibition of pain pathways by NMDA receptor antagonists are examples of preemptive analgesia. Using a combination of preemptive modalities and addressing patients' perceptions can aid in interrupting pathologic pain cycles. Positive and modest results have been obtained from animal and human preemptive trials, yet basic pathophysiology demonstrates the validity and importance of preemptive analgesia. Future studies are needed to test effective blockade of afferent input while controlling perception, hyperalgesia, and NMDA receptor activity. The Agency for Health Care Policy and Research now recommends a multifaceted approach to postoperative pain. The goal in pain management is to inhibit destructive pain pathways, maintain intraoperative analgesia, and prevent central sensitization. Preliminary results of multimodal preemptive analgesia trials continue to be promising.

Postoperative management of the exotic animal patient

Careful postoperative management is crucial for the success of any orthopedic surgical repair. The special needs of the exotic animal must be met during the immediate postoperative period and during hospitalization. Many exotic animals require a quiet, stress-free environment and careful attention to housing parameters, such as perching, temperature, and visual security. To provide adequate pain relief in these patients, analgesia should be given before, during, and after surgery. The drugs most often used for pain relief are NSAIDs and opioid analgesics. After surgery, monitor the healing process carefully with regular examinations and radiographs while remaining vigilant for potential problems such as osteomyelitis or nonunion. Physical therapy prevents the development of fracture disease, which includes joint or ligament contracture and bone or muscle mass loss. Because physical therapy affords the patient full use of the affected limb, it is considered a helpful practice in all patients. Physical therapy, however, is critical for free-ranging exotic animals that will be released back into the wild, such as birds of prey.

[Acute severe pain in emergencies. The key for efficient analgesia]

OBJECTIVE

To measure severe acute pain (SAP) frequency, to describe SAP management and to bring to view the conditions of analgesia success in emergency medicine.

DESIGN

Multicentre prospective survey: 7 days in Emergency Departments (ED), 30 days in Mobile Intensive Care Units (MICU). Multivariate analysis to measure the independent effect on pain relief of factors identified by Chi squared test.

SETTING

All of 6 ED and 8 MICU of a French region.

PATIENTS

Over 15 years of age.

MAIN OUTCOME MEASURES

Pain intensity was assessed with Visual Analog Scale (VAS) before and after ED or MICU management. SAP group (defined by initial VAS score > 40 mm) was analyzed for pain relief (defined by final VAS score < or = 40 mm). Influence on pain relief through pain aetiology, initial pain intensity, treatment delay and opioid use was analyzed.

RESULTS

1,082 fulfilled medical forms for 3,419 eligible patients. SAP frequency was estimated 36% (CI95 = 34-38%) in ED and 29% (CI95 = 25-33%) in MICU. SAP (n = 368) was often persistent: 45% (CI95 = 43-47%) after discharge from ED and 26% (CI95 = 22-30%) after MICU intervention. The prognostic factors of pain control success revealed by Chi squared test were: MICU (vs ED), treatment delay < or = 3 hours (vs > 3 hours), opioid use (vs non opioid use) and VAS pain level < or = 70 mm (vs > 70 mm). The last 3 factors were confirmed by multivariate analysis. Treatment delay, opioid use, and pain level were found to be determinants of efficient analgesia for SAP.

CONCLUSION

Despite the high frequency of SAP in ED and MICU, pain control is not satisfying. Opioid use and early treatment are determinant in analgesia efficiency for SAP and should be therefore encouraged to improve pain relief in emergency medicine.

Pre-emptive analgesia: an unsolved problem

Preemptive analgesia studies have provided mixed results, some showing benefit and others no benefit, whereas others have shown small differences that are probably not clinically useful. There is no consensus yet about whether preemptive analgesia is a clinically useful tool. This review examines the mechanisms of preemptive analgesia before surveying the recent literature. A new definition of preemptive analgesia is proposed that accommodates the need for a broader definition. Recently published trials confirm that confusion exists about what preemptive analgesia is, how to distinguish it from simple analgesia, and how to design trials that truly assess preemptive analgesia, defined as analgesia that is capable of modifying the central excitatory responses.

Amantadine, a N-methyl-D-aspartate receptor antagonist, does not enhance postoperative analgesia in women undergoing abdominal hysterectomy

N-methyl-D-aspartate (NMDA) antagonists administered before surgery will improve postoperative analgesia, presumably by inhibiting spinal sensitization processes. However, current clinical formulations of NMDA antagonists either enable only an oral application (i.e., dextromethorphan) or are associated with psychotropic side effects, as with the IV delivery of ketamine. Because of its noncompetitive NMDA receptor antagonist characteristics, amantadine may improve postoperative analgesia when administered before surgically induced trauma. In this prospective, randomized clinical study, we examined whether female patients undergoing elective abdominal hysterectomy experienced less postoperative pain when IV amantadine was applied in comparison with placebo before the start of surgery. Thirty patients were randomly assigned to receive 500 mL saline IV before the induction of standardized general anesthesia in Group 1 (Control group) or, in a double-blinded manner, 200 mg amantadine IV in 500 mL saline in Group 2 (Treatment group). Postoperative pain control was provided via IV patient-controlled analgesia with piritramide. During the first 48 h after tracheal extubation, pain perception was assessed by visual analog scales, and all analgesic requirements were documented. There were no significant differences between the two groups with respect to pain scores, postoperative analgesic requirements, and the incidence of side effects. Because of no differences in postoperative pain or opioid consumption, we conclude that a preoperative dose of 200 mg amantadine IV fails to enhance postoperative analgesia in patients undergoing elective abdominal hysterectomy.

IMPLICATIONS

Because of no differences in postoperative pain or opioid consumption, we conclude that a preoperative dose of 200 mg amantadine IV fails to enhance postoperative analgesia in patients undergoing elective abdominal hysterectomy.

Evidence that postoperative pain is a mediator of the tumor-promoting effects of surgery in rats

We have previously shown in rats that the provision of analgesic doses of morphine significantly reduces the tumor-promoting effects of undergoing and recovering from surgery. Because morphine had no effect in non-operated animals, and because a single preoperative dose given hours before tumor inoculation was effective, we have suggested that it is the pain-relieving effects of the drug that underlies its beneficial impact. To support and strengthen this suggestion, two different regimens of analgesia were employed, the systemic administration of the more selective mu-agonist, fentanyl, and the intrathecal (i.t.) administration of bupivacaine plus morphine. To assess host resistance against metastasis, we used a lung clearance assay of the MADB106 mammary adenocarcinoma, a natural killer (NK)-sensitive syngeneic cell line that metastasizes only to the lungs. Female and male Fischer 344 rats were randomly assigned to one of four groups using a 2x2 experimental design: experimental laparotomy under halothane anesthesia versus anesthesia alone, by drug treatment versus vehicle. In the first in vivo experiment, fentanyl was administered 20 min before surgery (40 microg/kg subcutaneously (s.c.)), and at the end of surgery in a slow-release suspension (20 microg/kg s.c.). In the second in vivo experiment, bupivacaine (10 microg) plus morphine (20 microg) in 50 microl was administered i.t. before surgery. Surgery resulted in a 3- to 4-fold increase in the lung retention of MADB106 cells in both males and females, and the observed surgery-induced increase in lung tumor retention was reduced by more than 65% in the fentanyl-treated animals and more than 45% in the animals receiving i.t. bupivacaine plus morphine. Neither drug regimen exerted effects in the anesthesia only animals. Surgery also resulted in a significant suppression of whole blood NK activity assessed at 5 h postoperatively, the same time point at which MADB106 tumor cells were inoculated in the in vivo studies. Unlike the in vivo study, fentanyl suppressed NK activity at this time point in non-operated rats, but had no effect in operated rats. Taken together, these findings strengthen the suggestion that the management of perioperative pain is a critical factor in preventing surgery-induced decreases in host resistance against metastasis. If similar relationships between pain and metastasis occur in humans, then pain control must become a priority in the postoperative care of individuals with cancer.

Current trends in perioperative pain management

Wider use of optimized multimodal accelerated postoperative recovery programs require that anesthesiologists step out of traditional operating room anesthesia roles and even beyond current pain management consultant roles. Development of optimal postoperative recovery services requires close collaboration between anesthesiologists, surgeons, nurses, physical therapists, administrators, and others involved in the management of patients after surgery. Optimization of perioperative care is an ongoing process enhanced by clinical investigation; however, making significant improvements to clinical practice does not have to wait for additional research data, but should proceed now, with broader application of techniques known to enhance rehabilitation and recovery. Based on existing data, the challenges of developing perioperative recovery services seem likely to be rewarded with improved patient outcomes and reduced cost.