An expert opinion on postoperative pain management, with special reference to new developments

Ultrasound assessment of residual gastric volume in older adults undergoing staged-bilateral total knee arthroplasty after consuming carbohydrate-containing fluids: a prospective observational study

BACKGROUND

We compared preoperative residual gastric volume (GV) between the first and second stages of total knee arthroplasty (TKA) in older adults after drinking carbohydrate-containing fluid 2 h prior to surgery.

METHODS

In this study, 36 patients, aged > 65 years, scheduled for staged bilateral TKA with one-week interval, were enrolled. The patients consumed 400 ml of carbohydrate-containing fluid 2 h prior to surgery. Before the induction of spinal anesthesia, the gastric antral cross-sectional area was measured at the first and second TKA using ultrasound, and the residual GV was calculated. The primary outcome was the residual GV. Qualitative GV (grades 0, 1, and 2) and analgesic consumption after the first TKA were assessed as secondary outcomes.

RESULTS

The GV (median [Q1, Q3]) was greater in the second-stage TKA (41.1 [22.5, 62.8] ml) than in the first-stage TKA (10.3 [0.0, 27.1] ml) (P < 0.001). In the qualitative assessment, the distribution was not different between the two stages of TKA (P = 0.219) and only one patient showed grade 2 gastric content in the second TKA. When opioid consumption was converted to an equivalent dose of morphine, an average of 53.9 mg of morphine was required after the first TKA.

CONCLUSIONS

Residual GV after drinking carbohydrate-containing fluid differed according to the stage of TKA, showing a larger residual GV in the second TKA than in the first one. In older adults scheduled to undergo bilateral staged TKA, caution is required in preoperative fasting practice, especially in second-stage surgery.

A Systematic Review of the Usage of Lidocaine in Hip Replacement Surgery

Hip replacement procedures, professionally known as hip arthroplasty, are one of the most common orthopedic procedures. Due to the variation in this procedure, the use and types of anesthetics differ. One such commonly used anesthetic is lidocaine. Since there are currently no standardized or general procedures for the application of lidocaine for perioperative hip arthroplasty procedures, this review aims to delve into this topic. A literature review surrounding the key terms "hip replacement" and "lidocaine" was performed on PubMed. After reviewing 24 randomized control trials, statistical analyses between groups that had no lidocaine versus groups that did were performed. The results showed that there was no statistical significance between various age groups and the use of lidocaine. One percent (1%) and 2% injected into the lumbar region were the most commonly reported doses of lidocaine, with 2% often being the first test dose. Other conclusions were that lidocaine was used for general anesthesia for individuals that underwent hip arthroplasty due to an underlying condition (cauda equina syndrome, ankylosing spondylitis, etc.). Lidocaine was also used for postoperative pain relief, which is a potential concern from its addictive qualities. This investigation outlines the current stance and usage of lidocaine in perioperative hip arthroplasty while noting its limitations.

Postoperative pain treatment after spinal fusion surgery: a systematic review with meta-analyses and trial sequential analyses

Supplemental Digital Content is Available in the Text.

Patients undergoing spinal surgery are at high risk of acute and persistent postoperative pain. Therefore, adequate pain relief is crucial. This systematic review aimed to provide answers about best-proven postoperative analgesic treatment for patients undergoing lumbar 1- or 2-level fusions for degenerative spine diseases. We performed a search in PubMed, Embase, and The Cochrane Library for randomized controlled trials. The primary outcome was opioid consumption after 24 hours postoperatively. We performed meta-analyses, trial sequential analyses, and Grading of Recommendations assessment to accommodate systematic errors. Forty-four randomized controlled trials were included with 2983 participants. Five subgroups emerged: nonsteroidal anti-inflammatory drugs (NSAIDs), epidural, ketamine, local infiltration analgesia, and intrathecal morphine. The results showed a significant reduction in opioid consumption for treatment with NSAID (P < 0.0008) and epidural (P < 0.0006) (predefined minimal clinical relevance of 10 mg). Concerning secondary outcomes, significant reductions in pain scores were detected after 6 hours at rest (NSAID [P < 0.0001] and intrathecal morphine [P < 0.0001]), 6 hours during mobilization (intrathecal morphine [P = 0.003]), 24 hours at rest (epidural [P < 0.00001] and ketamine [P < 0.00001]), and 24 hours during mobilization (intrathecal morphine [P = 0.03]). The effect of wound infiltration was nonsignificant. The quality of evidence was low to very low for most trials. The results from this systematic review showed that some analgesic interventions have the capability to reduce opioid consumption compared with control groups. However, because of the high risk of bias and low evidence, it was impossible to recommend a “gold standard” for the analgesic treatment after 1- or 2-level spinal fusion surgery.

Dissecting the Perioperative Care Bundle

Enhanced recovery after surgery (ERAS) protocols are comprehensive perioperative care pathways designed to mitigate the physiologic stressors associated with surgery and, in turn, improve clinical outcomes and lead to health care cost savings. Although individual components may differ, ERAS protocols are typically organized as multimodal care "bundles" that, when followed closely and in their entirety, are meant to generate amplified cumulative benefits. This manuscript examines some of the critical components, describes some areas where the science is weak (but dogma may be strong), and provides some of the evidence or lack thereof behind components of a standard ERAS protocol.

Opioid weaning and pain management in postsurgical patients at the Toronto General Hospital Transitional Pain Service

BACKGROUND

The perioperative period provides a critical window to address opioid use, particularly in patients with a history of chronic pain and presurgical opioid use. The Toronto General Hospital Transitional Pain Service (TPS) was developed to address the issues of pain and opioid use after surgery.

AIMS

To provide program evaluation results from the TPS at the Toronto General Hospital highlighting opioid weaning rates and pain management of opioid-naïve and opioid-experienced surgical patients.

METHODS

Two hundred fifty-one high-risk TPS patients were dichotomized preoperatively as opioid naïve or opioid experienced. Outcomes included pain, opioid consumption, weaning rates, and psychosocial/medical comorbidities.

RESULTS

Six months postoperatively, pain and function were significantly improved. Opioid-naïve and opioid-experienced patients reduced consumption by 69% and 44%, respectively. Forty-six percent and 26% weaned completely. Consumption at hospital discharge predicted weaning in opioid-naïve patients. Pain catastrophizing, neuropathy, and recreational drug use predicted weaning in opioid-experienced patients.

CONCLUSIONS

The TPS enabled almost half of opioid-naïve patients and one in four opioid-experienced patients to wean. The TPS successfully targets perioperative opioid use in complex pain patients.

Opioids and cancer: friend or foe?

PURPOSE OF REVIEW

Most cancer patients experience pain and many will require opioids. However, the effects of opioids on cancer progression, metastasis, and recurrence is increasingly being questioned. There is evidence that opioids affect immune system function, angiogenesis, apoptosis, and invasion in a potentially deleterious manner. This review will examine the preclinical and clinical evidence.

RECENT FINDINGS

Recent clinical data have struggled to find robust evidence that opioids promote cancer progression. Although most study has involved morphine, differential effects of other opioids on immune function and cancer are revealing a more complex picture.

SUMMARY

Although there is a biologically plausible story, evidence for the action of opioids on cancer is mixed. Indeed, it may even be that in the chronic setting morphine has a beneficial effect on outcome in certain cancer types. This review critically examines and evaluates the evidence for the action of opioids on the processes involved in cancer progression. In the light of the uncertainty of opioid effect on cancer, any decision making should be tempered by knowing that stress and pain undoubtedly contribute to cancer progression.

Gabapentin in procedure-specific postoperative pain management - preplanned subgroup analyses from a systematic review with meta-analyses and trial sequential analyses

Background

It has been argued that postoperative pain treatment should be “procedure-specific”, since different analgesics may have specific effects dependent on the surgical procedure. The aim of the present subgroup analysis was to compare the beneficial and harmful effects of perioperative gabapentin treatment in different surgical procedures.

Methods

Relevant databases were searched for randomized clinical trials (RCTs) comparing gabapentin versus placebo. Two authors independently screened titles and abstracts, extracted data and assessed risk of bias. The primary outcomes were differences in 24-h morphine consumption, and serious adverse events (SAE) between surgical procedures. These subgroup analyses were predefined in a PRISMA compliant systematic review registered at PROSPERO (ID: CRD42013006538). It was predefined that conclusions should primarily be based on trials classified as overall low risk of bias.

Results

Seventy-four RCTs with 5645 patients were included, assessing benefit and harm in cholecystectomy, hysterectomy, mastectomy, and arthroplasty surgery, spinal surgery, and thoracic surgery.

Only eight of 74 trials were classified as overall low risk of bias limiting our ability to conclude on the estimates in most meta-analyses. The differences between surgical procedures in these trials were not statistically significant when tested for subgroup differences. Fifteen trials with 1377 patients reported a total of 59 SAEs, most of which were observed in the thoracic surgery group.

Conclusion

Both beneficial and harmful effects in these subgroup analyses were influenced by bias and insufficient data, limiting conclusions. With these limitations, we could not adequately test for differences in beneficial or harmful outcomes between six surgical subgroups undergoing perioperative gabapentin treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12871-017-0373-8) contains supplementary material, which is available to authorized users.

The influence of excipients on physical and pharmaceutical properties of oral lyophilisates containing a pregabalin-acetaminophen combination

OBJECTIVES

The purpose of the study was to investigate and characterize the oral lyophilisates containing the pregabalin-acetaminophen drug combination and as xcipients mannitol with microcrystalline cellulose or hydroxypropyl methylcellulose, in order to conclude upon drug-excipient interactions and their stability implications, impact of excipients on drug release and on the physicochemical and mechanical properties of the pharmaceutical formulations.

METHODS

The oral tablets were made by using a Christ freeze-dryer alpha 2-4-LSC lyophilizer, and evaluated for stability, drug-excipient compatibility and homogeneity of the prepared pharmaceutical formulations. The formulations were evaluated for in vivo absorption in rabbits by histopathological exams.

RESULTS

FTIR and thermogravimetric analyses, DLS technique, SEM and NIR-CI studies confirmed the compatibility between compounds. From the determined physical and biochemical parameters of the formulations it was established that they are stable, homogeneous, and meet the conditions for orally disintegrating tablets.

CONCLUSION

In the case of the investigated pharmaceutical formulations the study evidenced the assembling through physical bonds between the excipients and the 'codrug' complex, which do not affect the release of the bioactive compounds.

Gabapentin for post-operative pain management - a systematic review with meta-analyses and trial sequential analyses

BACKGROUND

Perioperative pain treatment often consist of combinations of non-opioid and opioid analgesics, 'multimodal analgesia', in which gabapentin is currently used. The aim was to document beneficial and harmful effects of perioperative gabapentin treatment.

METHODS

Randomized clinical trials comparing gabapentin vs. placebo or active placebo in adult surgical patients receiving gabapentin perioperatively were included. This review was conducted using Cochrane standards, trial sequential analysis (TSA), and Grading of Recommendations Assessment, Development, and Evaluation (GRADE). The primary outcomes were 24-h opioid consumption and incidence of serious adverse events (SAE).

RESULTS

One hundred and thirty-two trials with 9498 patients were included. Thirteen trials with low risk of bias reported a reduction in 24-h opioid consumption of 3.1 mg [0.5, 5.6] [corrected]. In the analysis of gabapentin as add-on analgesic to another non-opioid analgesic regimen found a mean reduction in 24-h morphine consumption of 1.2 mg [-0.3, 2.6; TSA-adjusted CI: -0.3, 2.6] in trials with low risk of bias. [corrected]. Nine trials with low risk of bias reported a risk ratio of SAEs of 1.61 [0.91; 2.86; TSA-adjusted CI: 0.57, 4.57].

CONCLUSION

Based on GRADE assessment of the primary outcomes in trials with low risk of bias, the results are low or very low quality of evidence due to imprecision, inconsistency, and in some outcomes indirectness. Firm evidence for use of gabapentin is lacking as clinically relevant beneficial effect of gabapentin may be absent and harm is imminent, especially when added to multimodal analgesia.

Population Pharmacokinetic Modelling of Morphine, Gabapentin and their Combination in the Rat

PURPOSE

The combination of morphine and gabapentin seems promising for the treatment of postoperative and neuropathic pain. Despite the well characterised pharmacodynamic interaction, little is known about possible pharmacokinetic interactions. The aim of this study was to evaluate whether co-administration of the two drugs leads to modifications of their pharmacokinetic profiles.

METHODS

The pharmacokinetics of morphine, morphine-3-glucuronide and gabapentin were characterised in rats following subcutaneous injections of morphine, gabapentin or their combination. Non-linear mixed effects modelling was applied to describe the pharmacokinetics of the compounds and possible interactions.

RESULTS

The plasma-concentration-time profiles of morphine and gabapentin were best described using a three- and a one-compartment disposition model respectively. Dose dependencies were found for morphine absorption rate and gabapentin bioavailability. Enterohepatic circulation of morphine-3-glucuronide was modelled using an oscillatory model. The combination did not lead to pharmacokinetic interactions for morphine or gabapentin but resulted in an estimated ~33% diminished morphine-3-glucuronide formation.

CONCLUSIONS

The finding of a lack of pharmacokinetic interaction strengthens the notion that the combination of the two drugs leads to better efficacy in pain treatment due to interaction at the pharmacodynamic level. The interaction found between gabapentin and morphine-3-glucuronide, the latter being inactive, might not have any clinical relevance.

Co-administration of morphine and gabapentin leads to dose dependent synergistic effects in a rat model of postoperative pain

Despite much evidence that combination of morphine and gabapentin can be beneficial for managing postoperative pain, the nature of the pharmacological interaction of the two drugs remains unclear. The aim of this study was to assess the interaction of morphine and gabapentin in range of different dose combinations and investigate whether co-administration leads to synergistic effects in a preclinical model of postoperative pain. The pharmacodynamic effects of morphine (1, 3 and 7mg/kg), gabapentin (10, 30 and 100mg/kg) or their combination (9 combinations in total) were evaluated in the rat plantar incision model using an electronic von Frey device. The percentage of maximum possible effect (%MPE) and the area under the response curve (AUC) were used for evaluation of the antihyperalgesic effects of the drugs. Identification of synergistic interactions was based on Loewe additivity response surface analyses. The combination of morphine and gabapentin resulted in synergistic antihyperalgesic effects in a preclinical model of postoperative pain. The synergistic interactions were found to be dose dependent and the increase in observed response compared to the theoretical additive response ranged between 26 and 58% for the synergistic doses. The finding of dose-dependent synergistic effects highlights that choosing the right dose-dose combination is of importance in postoperative pain therapy. Our results indicate benefit of high doses of gabapentin as adjuvant to morphine. If these findings translate to humans, they might have important implications for the treatment of pain in postoperative patients.

TRPV1 antagonist attenuates postoperative hypersensitivity by central and peripheral mechanisms

BACKGROUND

Acute postoperative pain is one of the frequent reasons for pain treatment. However, the exact mechanisms of its development are still not completely clear. Transient receptor potential vanilloid 1 (TRPV1) receptors are involved in nociceptive signaling in various hypersensitive states. Here we have investigated the contribution of TRPV1 receptors expressed on cutaneous peripheral nociceptive fibers and in the spinal cord on the development and maintenance of hypersensitivity to thermal and mechanical stimuli following surgical incision. A rat plantar incision model was used to test paw withdrawal responses to thermal and mechanical stimuli. The effect of the TRPV1 receptor antagonist SB366791 was investigated 1) by intrathecal injection 15 min before incision and 2) intradermal injection before (30 min) and immediately after the surgery. Vehicle-injected rats and naïve animals treated identically were used as controls.

RESULTS

Plantar incision induced mechanical allodynia and hyperalgesia and thermal hyperalgesia. A single intrathecal administration of SB366791 significantly reduced postincisional thermal hyperalgesia and also attenuated mechanical allodynia, while mechanical hyperalgesia remained unaffected. Local intradermal SB366791 treatment reduced thermal hyperalgesia and mechanical allodynia without affecting mechanical hyperalgesia.

CONCLUSIONS

Our experiments suggest that both peripheral and spinal cord TRPV1 receptors are involved in increased cutaneous sensitivity following surgical incision. The analgesic effect of the TRPV1 receptor antagonist was especially evident in the reduction of thermal hyperalgesia. The activation of TRPV1 receptors represents an important mechanism in the development of postoperative hypersensitivity.

Adverse effects of perioperative paracetamol, NSAIDs, glucocorticoids, gabapentinoids and their combinations: a topical review

Post-operative pain affects millions of patients worldwide and the post-operative period has high rates of morbidity and mortality. Some of this morbidity may be related to analgesics. The aim of this review was to provide an update of current knowledge of adverse events (AE) associated with the most common perioperative non-opioid analgesics: paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), glucocorticoids (GCCs), gabapentinoids and their combinations. The review is based on data from systematic reviews with meta-analyses of analgesic efficacy and/or adverse effects of perioperative non-opioid analgesics, and randomised trials and cohort/retrospective studies. Generally, data on AE are sparse and related to the immediate post-operative period. For paracetamol, the incidence of AEs appears trivial. Data are inconclusive regarding an association of NSAIDs with mortality, cardiovascular events, surgical bleeding and renal impairment. Anastomotic leakage may be associated with NSAID usage. No firm evidence exists for an association of NSAIDs with impaired bone healing. Single-dose GCCs were not significantly related to increased infection rates or delayed wound healing. Gabapentinoid treatment was associated with increased sedation, dizziness and visual disturbances, but the clinical relevance needs clarification. Importantly, data on AEs of combinations of the above analgesics are sparse and inconclusive. Despite the potential adverse events associated with the most commonly applied non-opioid analgesics, including their combinations, reporting of such events is sparse and confined to the immediate perioperative period. Knowledge of benefit and harm related to multimodal pain treatment is deficient and needs clarification in large trials with prolonged observation.

Post-operative analgesic effects of paracetamol, NSAIDs, glucocorticoids, gabapentinoids and their combinations: a topical review

In contemporary post-operative pain management, patients are most often treated with combinations of non-opioid analgesics, to enhance pain relief and to reduce opioid requirements and opioid-related adverse effects. A diversity of combinations is currently employed in clinical practice, and no well-documented 'gold standards' exist. The aim of the present topical, narrative review is to provide an update of the evidence for post-operative analgesic efficacy with the most commonly used, systemic non-opioid drugs, paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs)/COX-2 antagonists, glucocorticoids, gabapentinoids, and combinations of these. The review is based on data from previous systematic reviews with meta-analyses, investigating effects of non-opioid analgesics on pain, opioid-requirements, and opioid-related adverse effects. Paracetamol, NSAIDs, COX-2 antagonists, and gabapentin reduced 24 h post-operative morphine requirements with 6.3 (95% confidence interval: 3.7 to 9.0) mg, 10.2 (8.7, 11.7) mg, 10.9 (9.1, 12.8) mg, and ≥ 13 mg, respectively, when administered as monotherapy. The opioid-sparing effect of glucocorticoids was less convincing, 2.33 (0.26, 4.39) mg morphine/24 h. Trials of pregabalin > 300 mg/day indicated a morphine-sparing effect of 13.4 (4, 22.8) mg morphine/24 h. Notably, though, the available evidence for additive or synergistic effects of most combination regimens was sparse or lacking. Paracetamol, NSAIDs, selective COX-2 antagonists, and gabapentin all seem to have well-documented, clinically relevant analgesic properties. The analgesic effects of glucocorticoids and pregabalin await further clarification. Combination regimens are sparsely documented and should be further investigated in future studies.

Perioperative nutrition: what is the current landscape?

Poor nutrition status has long been linked to increases in postoperative complications and adverse outcomes for the patient undergoing elective surgery. While optimal planning for nutrition therapy should be comprehensive spanning throughout the perioperative period, recent advances have focused on the concept of "prehabilitation" to best prepare the patient prior to the insult of surgery. Adding immune/metabolic modulating formulas the week of surgery with carbohydrate drinks to optimize glycogen deposition immediately prior to surgery, enhances patient recovery and return to baseline function. Such nutrition strategies should now be combined with a host of other practices (such as smoking cessation, weight loss, glucose control, and specialized exercise program) as part of a structured protocol to maximize patients' chances for a full and rapid recovery from their elective surgical procedure.

Regional anesthesia for acute pain management in elderly patients

Normal aging is a process that involves loss of functional reserve of most organ systems of the human body, most significantly: cardiovascular, pulmonary, renal and nervous systems. Advancements in both surgery and anesthesia have made it possible to operate more safely on the elderly population and those older patients with multiple severe co-morbidities that were not routinely possible in the recent past. Regional anesthesiologist have proven to be instrumental in this regard as regional anesthetic/analgesic techniques may now permit surgeons to operate on the elderly who were not ideal surgical candidates or unable to tolerate general anesthesia. In addition, regional techniques provide alternatives that may optimize acute pain control and reduce the incidence of devastating side effects during the perioperative period such as: myocardial infarction, pulmonary embolism, pneumonia, and also increases the opportunity to allow for early ambulation and shorter hospital stays. These anesthetic options now provide the elderly patient with better medical care alternatives, but also can show a significant financial impact on health care system resources. Further understanding on aging molecular biology, physiology and pathophysiology, together with technical improvements of regional anesthetic techniques will continue to make it safer and more efficacious to operate on the elderly population with evidence of reduced morbidity and mortality. Although there is only anecdotal evidence that regional anesthesia (RA) improves survival, there is little doubt that RA plays an important role in perioperative optimization of pain control and decreases pain management complications as well as a reduction in healthcare costs. Beyond traditional operating rooms, elderly patients may increasingly benefit from RA and acute pain management in Emergency Rooms, medical clinics and even within a patient’s home. Therefore, the focus of this review is directed toward geriatric patients and beneficial effects of RA on outcomes in the elderly.

Evaluation of DepoFoam(®) bupivacaine for the treatment of postsurgical pain

SUMMARY An extended-release, multivesicular liposome-encapsulated form of the local anesthetic bupivacaine, DepoFoam(®) bupivacaine (proposed proprietary name EXPAREL™), is in development for use as part of a multimodal regimen for the treatment of postsurgical pain. Placebo- and active-controlled clinical trials in patients who have undergone either orthopedic or soft-tissue procedures indicate that a single local administration into the surgical site results in analgesic activity for up to 3-4 days and decreases the use of opioid rescue medication. The safety profile of DepoFoam bupivacaine appears to be similar to that of bupivacaine HCl, and adverse events are dose-related.

Implementation of the quality management system improves postoperative pain treatment: a prospective pre-/post-interventional questionnaire study

Background

An organizational approach is proposed as an immediate solution for improving postoperative pain (POP) management. The aim was to evaluate the clinical effectiveness of a quality management system (QMS), based on procedure-specific, multimodal analgesic protocols, modified to meet the individual patients’ requirements.

Methods

Patients from the orthopaedic, gynaecological, visceral, and trauma surgery departments of the university hospital were involved in two prospective surveys. Survey 1 was performed at baseline and survey 2 was performed after the implementation of QMS within an interval of 1 year. The patients were asked to report pain intensity on the visual rating scale, incidence of analgesia-related side-effects, and incidence of pain interference with the items of life quality and their satisfaction with the treatment of POP.

Results

Patients from Survey 2 (n=251) reported 25–30% less pain than those from Survey 1 (n=269) (P<0.0001). Nausea was reported by 40% of the patients from Survey 1 vs 17% from Survey 2, vomiting by 25 vs 11% and fatigue by 76% in Survey 1 vs 30% in Survey 2 (P<0.0001). Life quality and patients’ satisfaction improved in Survey 2 vs Survey 1 (P<0.001).

Conclusions

The implementation of QMS allowed the reduction in POP intensity with a simultaneous decrease in analgesia-related side-effects. This has led to an increased quality of life and patient satisfaction.

Short stay and less pain after ambulatory anterior cruciate ligament (ACL) repair: COX-2 inhibitor versus glucocorticoid versus both combined

BACKGROUND

Many studies have demonstrated that either COX-2 antagonists or glucocorticoids are efficient analgesics after orthopaedic surgery. We wanted to evaluate if the combination of these two drugs was better than one drug alone when added to paracetamol, local anaesthesia, and cryo-cuff for outpatient anterior crucial ligament (ACL) surgery.

METHODS

In a double-blind design, 89 adult patients scheduled for day-case ACL repair in general anaesthesia were randomly assigned into three groups: The COXIB group (n = 30) received either 40 mg parecoxib iv or 120 mg etoricoxib orally 1 h before surgery. The STEROID group (n = 30) received 8 mg dexamethasone iv, and the combination group (Group COMBI, n = 29) received both.

RESULTS

At 24 h, Group COMBI had significantly lower visual analogue scale (0-10 cm) scores during rest (2.1 ± 1.3) (mean ± standard deviation) and movement (4.2 ± 2.5) when compared to both the COXIB group (P = 0.04) and the STEROID group (P = 0.035). The accumulated consumption of rescue opioids (5.2 ± 4,5 mg morphine) was also significantly lower at 24 h compared to the other groups (P = 0.02). Mean time to discharge from hospital was about 3 h in all groups. The pain scores in the post-anaesthetic care unit, mobilization at 24 h and 7 days, and general level of satisfaction were similar between the groups.

CONCLUSION

The combination of a COX-2 inhibitor and dexamethasone results in better pain relief 24 h after surgery in patients undergoing outpatient ACL surgery, compared to COX-2 inhibitor alone or dexamethasone alone. With a dedicated multimodal pain regime, most ACL patients may be discharged within 3 h.

Capsaicin instillation for postoperative pain following total knee arthroplasty: a preliminary report of a randomized, double-blind, parallel-group, placebo-controlled, multicentre trial

BACKGROUND

Pain following total knee arthroplasty (TKA) interferes with rehabilitation. Capsaicin applied in high concentration to nociceptors can cause relatively selective C-fibre desensitization for a period of weeks to months. Resultant long-lasting analgesia might facilitate rehabilitation.

OBJECTIVE

The objective of this study was to determine if direct instillation of a high-concentration capsaicin preparation into the wound following TKA would provide pain relief, improve physical functioning and rehabilitation, and reduce opioid requirements.

METHODS

This was a randomized, double-blind, parallel-group, placebo-controlled, multicentre, phase II trial carried out in a teaching hospital system. Non-opioid-tolerant males or females aged 18-85 years with a body mass index (BMI) ≤45 kg/m2, American Society of Anesthesiologists (ASA) physical status 1-3 and end-stage osteoarthritis who were scheduled for primary unilateral TKA were included. Patients received placebo vehicle or capsaicin 15 mg (Anesiva 4975) by instillation immediately prior to wound closure. Surgery was conducted under spinal anaesthesia and femoral nerve block. Postoperative rescue analgesia consisted of intravenous patient-controlled analgesia with morphine for 24 hours; oral oxycodone was provided thereafter as needed. It was hypothesized prior to data collection that capsaicin instillation would reduce postoperative pain scores and result in improved patient satisfaction and ambulation. The primary outcome was the area under the numerical rating scale (NRS) for pain score-time curve from 4 to 24 hours (AUC(4-24)). NRS for pain scores were obtained every 4 hours for 24 hours then daily with ambulation and physical therapy for 3 days. Function and patient satisfaction were assessed at 14, 28 and 42 days.

RESULTS

Data from 14 patients (seven per group) from a single centre (data were not available from other sites because of sponsor bankruptcy) were available for this preliminary report. AUC(4-24) was not significantly different clinically (placebo 70.3; capsaicin 65.7) in this sample; however, a significant opioid-sparing effect was seen in the capsaicin group despite the fact that patients in this group had higher BMIs. Pain scores tended to be lower in the capsaicin group, despite the fact that patients in this group received significantly less rescue opioid medication. Morphine use from 12-24 hours was lower (capsaicin group mean 13.4 mg; 95% confidence interval [CI] 7.4, 19.5; range 10-21 mg vs placebo group mean 25.9 mg; 95% CI 19.8, 32.0; range 15-36 mg; p = 0.009). Total intravenous and oral opioid in morphine equivalents over 72 hours was also lower with capsaicin compared with placebo (p = 0.03). Active range of motion (ROM) was also significantly improved at day 14 in the capsaicin group compared with the placebo group (p = 0.0014). A higher percentage of patients in the capsaicin group reported being extremely satisfied with their treatment. The only statistically significant difference in treatment-emergent adverse events was for pruritus, which was more frequent in the placebo group (p = 0.03).

CONCLUSION

Despite having higher BMIs, patients in the capsaicin group achieved comparable or better pain scores with significantly less opioid use in the first 3 postoperative days. They also had less pruritus, which may have been a consequence of the opioid-sparing effect. The effects of capsaicin with respect to function, however, appeared to be longer lasting, with improved active ROM reported at 14 days.

The surgical rectus sheath block for post-operative analgesia: a modern approach to an established technique

OBJECTIVE

To describe the surgical rectus sheath block for post-operative pain relief following major gynaecological surgery.

TECHNIQUE

Local anaesthetic (20 ml 0.25% bupivacaine bilaterally) is administered under direct vision to the rectus sheath space at the time of closure of the anterior abdominal wall.

STUDY DESIGN

We conducted a retrospective case note review of 98 consecutive patients undergoing major gynaecological surgery for benign or malignant disease who received either standard subcutaneous infiltration of the wound with local anaesthetic (LA, n=51) or the surgical rectus sheath block (n=47) for post-operative pain relief.

MAIN OUTCOME MEASURES

(1) Pain scores on waking, (2) duration of morphine-based patient controlled analgesia (PCA), (3) quantity of morphine used during the first 48 post-operative hours and (4) length of post-operative stay.

RESULTS

The groups were similar in age, the range of procedures performed and the type of pathology observed. Patients who received the surgical rectus sheath block had lower pain scores on waking [0 (0-1) vs. 2 (1-3), p<0.001], required less morphine post-operatively [12 mg (9-26) vs. 36 mg (30-48), p<0.001], had their PCAs discontinued earlier [24h (18-34) vs. 37 h (28-48), p<0.001] and went home earlier [4 days (3-4) vs. 5 days post-op (4-8), p<0.001] [median (interquartile range)] than patients receiving standard subcutaneous local anaesthetic into the wound.

CONCLUSIONS

The surgical rectus sheath block appears to provide effective post-operative analgesia for patients undergoing major gynaecological surgery. A randomised controlled clinical trial is required to assess its efficacy further.

Morphine use in cancer surgery

Morphine is the core of perioperative pain management. However, when it comes to cancer surgery the possibility that this drug might affect tumor recurrence and metastasis has raised concerns. The results of two recent retrospective clinical trials indicated that regional anesthesia/analgesia might be beneficial in prostate and breast cancer surgery. It was proposed that morphine could be responsible for the higher recurrence and mortality rate observed in the general anesthesia/opioid analgesia groups. Nevertheless, the results of several other retrospective studies and one randomized prospective trial failed to confirm any advantage for regional anesthesia/analgesia over general anesthesia and opioid analgesia. Moreover laboratory data on the effect of morphine on cancer are contradictory, ranging from tumor-promoting to anti-tumor effects. Considering that surgical stress and pain promote the recurrence and spread of cancer, choosing a proper analgesic strategy is of high significance. Although the question of whether morphine causes any harm to cancer patients remains unanswered, alternative analgesic regimens could be used concomitant to or instead of morphine to limit its potential adverse effects.

Pregabalin and dexamethasone improves post-operative pain treatment after tonsillectomy

BACKGROUND

Post-tonsillectomy pain can be severe. We investigated the analgesic effect from combinations of paracetamol, pregabalin and dexamethasone in adults undergoing tonsillectomy.

METHODS

In this randomized double-blind study, 131 patients were assigned to either group A (paracetamol+placebo), group B (paracetamol+pregabalin+placebo) or group C (paracetamol+pregabalin+dexamethasone). Pre-operatively, patients received either paracetamol 1000 mg, pregabalin 300 mg, dexamethasone 8 mg or placebo according to their allocation. Post-operative pain treatment included paracetamol 1000 mg 4× and ketobemidone 2.5 mg p.n. Ketobemidone consumption, pain scores [visual analogue scale (VAS)], nausea, sedation, dizziness, number of vomits and consumption of ondansetron were recorded 2, 4 and 24 h after the operation. P<0.05 was considered statistically significant.

RESULTS

The mean 24-h VAS-pain score at rest was reduced in group C (P<0.003) vs. group A. The mean 24-h VAS-pain scores during swallowing were reduced in group B (P=0.009) and group C (P<0.003) vs. group A. Consumption of ketobemidone (1-4 h post-operatively) was lower in group B (P=0.003) and group C (P=0.003) vs. group A. The mean 24-h dizziness score was higher in group B (P<0.003) and C (P=0.003) vs. group A. Other parameters including re-operation for post-tonsillectomy bleeding were not different between groups.

CONCLUSION

Pregabalin and pregabalin+dexamethasone reduced post-operative pain scores and consumption of ketobemidone following tonsillectomy. Dizziness was increased with pregabalin.

Anesthetic Routines: The Anesthesiologist's Role in GI Recovery and Postoperative Ileus

All patients undergoing bowel resection experience postoperative ileus, a transient cessation of bowel motility that prevents effective transit of intestinal contents or tolerance of oral intake, to varying degrees. An anesthesiologist plays a critical role, not only in the initiation of surgical anesthesia, but also with the selection and transition to effective postoperative analgesia regimens. Attempts to reduce the duration of postoperative ileus have prompted the study of various preoperative, perioperative, and postoperative regimens to facilitate gastrointestinal recovery. These include modifiable variables such as epidural anesthesia and analgesia, opioid-sparing anesthesia and analgesia, fluid restriction, colloid versus crystalloid combinations, prokinetic drugs, and use of the new peripherally acting mu-opioid receptor (PAM-OR) antagonists. Review and appropriate adaptation of these multiple modifiable interventions by anesthesiologists and their surgical colleagues will facilitate implementation of a best-practice management routine for bowel resection procedures that will benefit the patient and the healthcare system.

Central sensitization: implications for the diagnosis and treatment of pain

Nociceptor inputs can trigger a prolonged but reversible increase in the excitability and synaptic efficacy of neurons in central nociceptive pathways, the phenomenon of central sensitization. Central sensitization manifests as pain hypersensitivity, particularly dynamic tactile allodynia, secondary punctate or pressure hyperalgesia, aftersensations, and enhanced temporal summation. It can be readily and rapidly elicited in human volunteers by diverse experimental noxious conditioning stimuli to skin, muscles or viscera, and in addition to producing pain hypersensitivity, results in secondary changes in brain activity that can be detected by electrophysiological or imaging techniques. Studies in clinical cohorts reveal changes in pain sensitivity that have been interpreted as revealing an important contribution of central sensitization to the pain phenotype in patients with fibromyalgia, osteoarthritis, musculoskeletal disorders with generalized pain hypersensitivity, headache, temporomandibular joint disorders, dental pain, neuropathic pain, visceral pain hypersensitivity disorders and post-surgical pain. The comorbidity of those pain hypersensitivity syndromes that present in the absence of inflammation or a neural lesion, their similar pattern of clinical presentation and response to centrally acting analgesics, may reflect a commonality of central sensitization to their pathophysiology. An important question that still needs to be determined is whether there are individuals with a higher inherited propensity for developing central sensitization than others, and if so, whether this conveys an increased risk in both developing conditions with pain hypersensitivity, and their chronification. Diagnostic criteria to establish the presence of central sensitization in patients will greatly assist the phenotyping of patients for choosing treatments that produce analgesia by normalizing hyperexcitable central neural activity. We have certainly come a long way since the first discovery of activity-dependent synaptic plasticity in the spinal cord and the revelation that it occurs and produces pain hypersensitivity in patients. Nevertheless, discovering the genetic and environmental contributors to and objective biomarkers of central sensitization will be highly beneficial, as will additional treatment options to prevent or reduce this prevalent and promiscuous form of pain plasticity.