Gabapentin: an alternative to the cyclooxygenase-2 inhibitors for perioperative pain management

It's complicated: The relationship of non-narcotic medications and postoperative opioid use in radical cystectomy patients

INTRODUCTION

The effect of individual non-narcotic analgesics in cystectomy enhanced recovery after surgery (ERAS) is unknown. Additionally, many non-narcotic medications are associated with side effects pertinent to the cystectomy population. To better understand the actual use and utility of these medications, we sought to characterize the association between non-narcotic medications and milligram morphine equivalent (MME) narcotic score during the postoperative inpatient stay.

METHODS

We reviewed 260 consecutive ERAS cystectomy patients. The MME impact of non-narcotic compliance and cumulative dose of medication received was evaluated separately with general linear models. We also assessed relationship of non-narcotic compliance to patient reported pain score, length of stay (LOS), and time to return of bowel function (ROBF) and performed manual review of postoperative documentation to identify reasons for medication noncompliance.

RESULTS

Compliance with postoperative acetaminophen, gabapentin, and ketorolac was low. There was an inverse relationship between ketorolac dose and MME on postoperative day 1 (-0.026 MME/mg; P = 0.004) and postoperative day 2 (-0.33 MME/mg; P < 0.001). Compliance with ketorolac was associated with lower MME on postoperative day 1 (26.1 MME v. 33.6 MME; P = 0.023). There were no such associations identified with gabapentin or acetaminophen. Gabapentin compliance was associated with earlier ROBF (3.7 days v. 4.3 days; P = 0.006). Ketorolac compliance was associated with lower pain score on POD1 (3.25 VAS v. 4.07 VAS; P = 0.019) and POD2 (3.05 VAS v. 3.85 VAS; P = 0.040) There was no association between medication compliance and LOS. The most common reasons identified for non-compliance with gabapentin and ketorolac were renal function concerns (38% and 40% respectively), bleeding concerns with ketorolac (20%) and concerns for neurologic adverse effect with gabapentin (16%).

CONCLUSION

Compliance with non-narcotic medications in our ERAS cystectomy protocol was poor. There was a modest association with ketorolac and postoperative MME but no association with gabapentin or acetaminophen. Further study will clarify the role of these medications for cystectomy patients. Component specific analysis of protocolized care is valuable and may alter care pathways.

Lesser Known Uses of γ-Aminobutyric Acid Analogue Medications in Otolaryngology

OBJECTIVES/HYPOTHESIS

In otolaryngology, γ-aminobutyric acid (GABA) analogues have been previously analyzed for their roles in neuropathic pain, chronic cough, tinnitus, and perioperative analgesia. The primary aim of this study is to comprehensively summarize and synthesize the existing evidence for lesser known uses of gabapentin and pregabalin in otolaryngology.

STUDY DESIGN

A scoping review conducted of the available English-language literature was performed by two authors through April 1, 2021.

METHODS

The Preferred Reporting Items for Systematic Review and Meta-Analysis criteria were followed, and a quality assessment of included studies was performed using the Methodological Index for Non-Randomized Studies.

RESULTS

Ten studies met inclusion criteria. Three studies found that gabapentin may reduce gastrostomy tube usage and improve swallowing function in head and neck cancer patients undergoing radiation therapy (RT). Three studies suggested that gabapentin may help reduce opiate use when used as a primary analgesic in patients with radiation-induced mucositis. One study demonstrated that pregabalin-reduced trismus severity in patients with radiotherapy-induced trismus. One study demonstrated gabapentin may be useful in patients with phonasthenia. Two studies demonstrated that GABA analogues may be a useful adjunct in patients with globus pharyngeus in the context of likely laryngeal sensory neuropathy.

CONCLUSIONS

The most promising potential uses for GABA analogues identified in this review are for improving swallowing, trismus, and narcotic overuse after RT. The benefit of GABA analogues for improving nonorganic voice disorders is also promising while the benefit for globus pharyngeus when possibly related to laryngeal sensory neuropathy is inconclusive. Laryngoscope, 2021.

Dose-related beneficial and harmful effects of gabapentin in postoperative pain management - post hoc analyses from a systematic review with meta-analyses and trial sequential analyses

Background

During the last 15 years, gabapentin has become an established component of postoperative pain treatment. Gabapentin has been employed in a wide range of doses, but little is known about the optimal dose, providing the best balance between benefit and harm. This systematic review with meta-analyses aimed to explore the beneficial and harmful effects of various doses of gabapentin administered to surgical patients.

Materials and methods

Data in this paper were derived from an original review, and the subgroup analyses were predefined in an International Prospective Register of Systematic Reviews published protocol: PROSPERO (ID: CRD42013006538). The methods followed Cochrane guidelines. The Cochrane Library’s CENTRAL, PubMed, EMBASE, Science Citation Index Expanded, Google Scholar, and FDA database were searched for relevant trials. Randomized clinical trials comparing gabapentin versus placebo were included. Four different dose intervals were investigated: 0–350, 351–700, 701–1050, and >1050 mg. Primary co-outcomes were 24-hour morphine consumption and serious adverse events (SAEs), with emphasis put on trials with low risk of bias.

Results

One hundred and twenty-two randomized clinical trials, with 8466 patients, were included. Sixteen were overall low risk of bias. No consistent increase in morphine-sparing effect was observed with increasing doses of gabapentin from the trials with low risk of bias. Analyzing all trials, the smallest and the highest dose subgroups demonstrated numerically the most prominent reduction in morphine consumption. Twenty-seven trials reported 72 SAEs, of which 83% were reported in the >1050 mg subgroup. No systematic increase in SAEs was observed with increasing doses of gabapentin.

Conclusion

Data were sparse, and the small number of trials with low risk of bias is a major limitation for firm conclusions. Taking these limitations into account, we were not able to demonstrate a clear relationship between the dosage of gabapentin and opioid-sparing or harmful effects. These subgroup analyses are exploratory and hypothesis-generating for future trialists.

Preemptive analgesia for postoperative hysterectomy pain control: systematic review and clinical practice guidelines

OBJECTIVE

The objective of the study was to investigate the effectiveness of preemptive analgesia at pain control in women undergoing total abdominal hysterectomy.

DATA SOURCES

Eligible studies, published through May 31, 2016, were retrieved through Medline, Cochrane Central Register for Controlled Trials, and Cochrane Database of Systematic Reviews.

STUDY ELIGIBILITY

We included randomized controlled trials with the primary outcome of pain control in women receiving a preemptive medication prior to total abdominal hysterectomy. Comparators were placebo, different doses of the same medication as intervention, or other nonnarcotic or narcotic medication.

STUDY APPRAISAL AND SYNTHESIS METHODS

Study data were extracted by one reviewer and confirmed by a second reviewer. For each outcome we graded the quality of the evidence. Studies were classified by the type of medication used and by outcome type.

RESULTS

Eighty-four trials met eligibility, with 69 included. Among nonnarcotic medications, paracetamol, gabapentin, and rofecoxib combined with gabapentin resulted in improvements in pain assessment compared with placebo and other nonnarcotic medications. Patient satisfaction was higher in patients who were given gabapentin combined with paracetamol compared with gabapentin alone. Use of preemptive paracetamol, gabapentin, bupivacaine, and phenothiazine resulted in less narcotic usage than placebo. All narcotics (ketamine, morphine, fentanyl) resulted in improved pain control compared with placebo. Narcotics had a greater reduction in pain assessment scores compared with nonnarcotics, and their use resulted in lower total narcotic usage.

CONCLUSION

Preemptive nonnarcotic and narcotic medications prior to abdominal hysterectomy decrease total narcotic requirements and improve patient postoperative pain assessment and satisfaction scores.

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.

Combination of gabapentin and celecoxib for analgesia after major orthopedic surgery: a randomized, controlled trial

Background: The use of analgesics with different mechanism of action enhances post-operative pain relief by opioids. Both celecoxib and gabapentin have opioid-sparing effect, but it is unclear whether combination of the two drugs accentuates postoperative analgesia and further reduced opioid requirement.

Objective: Determine whether the perioperative use of celecoxib in combination with gabapentin reduces the amount of post-operative opioid consumption in comparison to celecoxib alone or gabapentin alone in patients that have major orthopedic surgery.

Materials and methods: Randomized double-blinded placebo controlled trial was done in 99 patients underwent major orthopedic surgery. They were randomly allocated into four groups. One to two hours before anesthesia, they received midazolam 7.5 mg plus study drugs. Group P received placebo plus placebo at 12 and 24 hours later. Group C received celecoxib 400 mg plus celecoxib 200 mg at 12 and 24 hour later. Group G received gabapentin 400 mg plus gabapentin 300 mg at 12 and 24 hour later. Finally, group CG received celecoxib 400 mg + gabapentin 400 mg plus celecoxib 200 mg + gabapentin 300 mg at 12 and 24 hour later. The patients underwent surgery under general anesthesia. Post-operative pain was treated by intravenous morphine patient-controlled analgesia.

Results: Median morphine consumption (minimum-maximum) in twenty-four hours was 18.0, 15.0, 15.5, and 8.0 mg, in group P, C, G, and CG, respectively. The group CG significantly consumed less morphine (41%) in 24 hour than group G, but not significantly less (38%) than group C. Pain score, sedation score, and nausea/vomiting at postoperative hour 1, 4, 8, 12, 16, 20, and 24 was not significantly different.

Conclusion: Combination of celecoxib and gabapentin further accentuated post-operative analgesia by morphine comparing to celecoxib or gabapentin alone without change in pain score and other side effects of the medications.

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.

The Effect of Preoperative Gabapentin on Postoperative Nausea and Vomiting: A Meta-Analysis

BACKGROUND

Preoperative gabapentin has been shown to improve postoperative pain and limit reliance on opioid analgesia. On the basis of an alternative mechanism, our group investigated the ability of preoperative gabapentin to prevent postoperative nausea and vomiting (PONV).

METHODS

We performed a meta-analysis of trials that reported outcomes on the effect of preoperative gabapentin on PONV end points in patients undergoing general anesthesia. In our primary analysis, we calculated the pooled antiemetic effects of preoperative gabapentin in studies with PONV as the primary end point. In our secondary analysis, we calculated the pooled effects in trials involving preoperative gabapentin that reported on the side effects, nausea and vomiting.

RESULTS

Among the trials designed with PONV as a primary end point (8 trials; n = 838), preoperative gabapentin was associated with a significant reduction in PONV (risk ratio [RR] = 0.60; 99% confidence interval [CI], 0.50-0.72; P < 0.0001), nausea (RR = 0.34; 99% CI, 0.20-0.56; P < 0.0001), and vomiting (RR = 0.34; 99% CI, 0.19-0.61; P = 0.0002) at 24 hours. Among all included trials (44 trials; n = 3489) that reported on the side effects, nausea and vomiting, similar reductions were noted in PONV with preoperative gabapentin administration. Subgroup analysis of trials excluding repeat dosing, thiopental induction, and nitrous oxide maintenance and including high-risk surgery resulted in similar PONV efficacy. Preoperative gabapentin is also associated with significantly increased rates of postoperative sedation (RR = 1.22; 95% CI, 1.02-1.47; P = 0.03) compared with control.

CONCLUSIONS

Preoperative gabapentin is associated with a significant reduction in PONV among studies designed to investigate this end point. Preoperative gabapentin should be considered not only as part of a multimodal approach to postoperative analgesia, but also for prevention of PONV.

Anesthesia for the elderly outpatient

PURPOSE OF REVIEW

As the number of ambulatory surgery procedures continues to grow in an aging global society, the implementation of evidence-based perioperative care programs for the elderly patients will assume increased importance.

RECENT FINDINGS

Increasing evidence supports the expanded use of ambulatory surgery for managing elderly patients undergoing elective surgery procedures.

SUMMARY

This review article describes the demographics of ambulatory surgery in the elderly population. This review article describes the effects of aging on the responses of geriatric patients to anesthetic and analgesic drugs used during ambulatory surgery. Important considerations in the preoperative evaluation of elderly outpatients with co-existing diseases, as well as the advantages and disadvantages of different anesthetic techniques on a procedural-specific basis, and recommendations regarding the management of common postoperative side-effects (including delirium and cognitive dysfunction, fatigue, dizziness, pain, and gastrointestinal dysfunction) after ambulatory surgery. Finally, we discuss the future challenges related to the continued expansion of ambulatory surgery practice in this growing segment of our surgical population. The role of anesthesiologists as perioperative physicians is of critical importance for optimizing surgical outcomes for elderly patients undergoing ambulatory surgery. Providing high-quality, evidence-based anesthetic and analgesic care for elderly patients undergoing elective operations on an ambulatory basis will assume greater importance in the future.

Perioperative management of elderly patients

The older population only represents 13.7% of the US population but has grown by 21% since 2002. The centenarian population is growing at a faster rate than the total US population. This unprecedented growth has significantly increased surgical demand. The establishment of quality and performance improvement data has allowed researchers to focus attention on the older patient population, resulting in an exponential increase in studies. Although there is still much work to be done in this field, overlying themes regarding the perioperative management of elderly patients are presented in this article based on a thorough literature review.

Preemptive use of gabapentin in abdominal hysterectomy: a systematic review and meta-analysis

OBJECTIVE

To examine the evidence of preemptive use of gabapentin in abdominal hysterectomy.

DATA SOURCES

We conducted an electronic based search using the following databases: PubMed, EMBASE, Ovid MEDLINE, ClinicalTrials.gov, and Cochrane Central Register of Controlled Trials. The following medical subject heading terms, keywords, and their combinations were used: "postoperative pain, hysterectomy, gynecologic surgical procedures, gabapentin, preemptive analgesia, and preemptive anesthesia." We manually searched the reference lists of identified studies.

METHODS OF STUDY SELECTION

Randomized controlled trials of women who underwent a total abdominal hysterectomy, with or without bilateral salpingo-oophorectomy, under general anesthesia were examined. Only trials with preoperative dose of gabapentin were included.

TABULATION, INTEGRATION, AND RESULTS

The meta-analysis and systematic review were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Fourteen trials met the inclusion criteria. The pooled data consisted of 448 cases in the gabapentin group and 443 others in the control group. The 24-hour cumulative narcotic consumption and the visual analog scale scores at 24 hours postoperatively were used for postoperative pain assessment. There was a significant decrease in morphine consumption at 24 hours when gabapentin was administered before surgery (from 24.3-55.9 mg to 13.2-42.7 mg, standardized mean difference -0.69) as well before and after surgery (from 25.7-80 mg to 20.3-55 mg, standardized mean difference -1.45), respectively. Metaregression analysis showed that the effect of gabapentin in reducing morphine consumption (compared with placebo) at 24 hours was stronger in the preoperative only group than in the preoperative and postoperative groups. Preemptive gabapentin decreased visual analog scale from 9-42.7 to 2-25.3 (standardized mean difference -1.03, 95% confidence interval [CI] -1.36 to -0.71). Compared with the control group (16.1-96.7%), the rate of nausea was less in the gabapentin group (11.6-70%, relative risk 0.76, 95% CI 0.66-0.88).

CONCLUSION

Preemptive administration of gabapentin is effective in decreasing postoperative pain scores, narcotic consumption, and nausea, and vomiting.

LEVEL OF EVIDENCE

I.

Postoperative pain and long-term functional outcome after administration of gabapentin and pregabalin in patients undergoing spinal surgery

STUDY DESIGN

Prospective, double-blind study, randomized control trial.

OBJECTIVE

To evaluate and compare the analgesic efficacy, adverse effects, and clinical utility of gabapentin and pregabalin in postoperative pain management, long-term functional outcome, and quality of life in patients undergoing spinal surgery.

SUMMARY OF BACKGROUND DATA

Patient outcome after lumbar discectomy for radicular low back pain is variable and the benefit is inconsistent. The most common persistent symptoms are pain, motor deficit, and decreased functional status.

METHODS

This study was conducted in 90 patients belonging to the 18 to 75 age group of either sex undergoing spinal surgery under general anesthesia. Group A received 300 mg of gabapentin, group B received 75 mg of pregabalin, whereas group C received placebo 1 dose 1 hour before surgery and 8 hourly for 7 days, thereafter. The outcome of postoperative static and dynamic pain and functional outcome was recorded using 3 questionnaires-visual analogue scale, Prolo functional and economic score, Oswestry Disability Index score from preoperative period to 3 months postoperatively.

RESULTS

Among the 3 groups, subjects receiving pregabalin showed consistently reduced static and dynamic pain intensity and also required lesser amount of rescue drug throughout the postoperative period. There was statistically significant difference (P < 0.05) in the Prolo score and Oswestry Disability Index score at all time intervals between group B and group C. Although, significant difference in the functional outcome between group A and group B was seen at 3 months.

CONCLUSION

Preoperative pregabalin administration is associated with less pain intensity and improved functional outcomes 3 months after lumbar discectomy followed by gabapentin and then placebo.

LEVEL OF EVIDENCE

2.

Guidelines for the management of postoperative pain after total knee arthroplasty

This clinical practice guideline was approved by Korean Knee Society on February 28, 2012. It is based on a systematic review of published studies on the management of postoperative pain after total knee arthroplasty and was developed to include the overall pain management modalities. The purpose of the guideline is to help improve treatment based on current best evidence. Eleven recommendations have been developed based on a systematic review of research evidence and the consensus opinions of a multidisciplinary working group of experts. These recommendations will be revised regularly following systematic review of new research evidence as this becomes available.

Postoperative gabapentin to prevent postoperative pain: a randomized clinical trial

BACKGROUND

Gabapentin is an anticonvulsant that has postoperative analgesic effects but there are limited studies on its postoperative administration.

OBJECTIVES

The present study was conducted to evaluate the effect of the postoperative oral gabapentin on pain and morphine consumption.

PATIENTS AND METHODS

In a double blind, randomized study, 64 patients undergoing internal fixation of tibia under spinal anesthesia were randomly assigned to receive oral gabapentin or placebo immediately after the surgery. Pain scores were recorded at time points of 2, 12 and 24 hours postoperatively using visual analog scale (VAS). Time duration from the end of surgery until morphine administration and total morphine requirement in the first 24 hours were recorded.

RESULTS

The estimated duration of surgeries was 120-150 minutes. VAS score was not significantly different between the two groups at 2, 12 and 24 hours after surgery. There was no significant morphine consumption difference between the groups.

CONCLUSIONS

Our study showed no significant analgesic efficacy of oral gabapentin 300 mg immediately after tibia internal fixation surgery under spinal anesthesia at time points of 2, 12 and 24 hours postoperatively.

Gabapentin augments the antihyperalgesic effects of diclofenac sodium through spinal action in a rat postoperative pain model

BACKGROUND

Gabapentin and nonsteroidal antiinflammatory drugs (NSAIDs) attenuate postoperative pain and neuropathic pain in humans. The combination of gabapentin and NSAIDs is effective for postoperative pain and enhances functional recovery after surgery. Intrathecal administration of gabapentin or NSAIDs inhibits hyperalgesia in a rat postoperative pain model. However, there is no information on the effects of intrathecal administration of a combination of gabapentin and NSAIDs. We therefore investigated the effects of intrathecal administration of gabapentin and NSAIDs in a rat model of postoperative pain.

METHODS

Rats were prepared for intrathecal catheters under halothane anesthesia. Two days after catheterization, gabapentin (4, 40, or 400 μg per 20 μL of saline), diclofenac sodium, a nonselective cyclooxygenase inhibitor (2, 20, or 200 μg per 20 μL of 6% glucose), 20 μL saline, 20 μL 6% glucose, and a combination of gabapentin and diclofenac (40 μg gabapentin + 20 μg diclofenac and 4 μg gabapentin + 2 μg diclofenac per 20 μL 6% glucose) were injected intrathecally. We performed a hindpaw incision 30 minutes after injection. Each group consisted of 6 rats. The mechanical threshold was measured to evaluate secondary hyperalgesia using von Frey filaments before intrathecal catheterization and at 2 hours, and 1, 3, 5, and 7 days after paw incision.

RESULTS

Gabapentin 400 μg attenuated mechanical hyperalgesia for 7 days compared with the control group. Diclofenac 200 μg inhibited hyperalgesia for 5 days compared with the control group. The 40 μg gabapentin + 20 μg diclofenac group had a significantly reduced secondary hyperalgesic response in 2 hours and 1 day compared with 40 μg gabapentin and 20 μg diclofenac, respectively. The 4 μg gabapentin + 2 μg diclofenac group had a significantly reduced secondary hyperalgesic response in 2 hours and 1 day compared with 2 μg diclofenac. The withdrawal threshold on the contralateral paw did not change compared with the preincision threshold.

CONCLUSION

Intrathecal administration of gabapentin and diclofenac in combination reduced secondary hyperalgesia at doses having no antihyperalgesic effects when given individually. Our results suggest that gabapentin and diclofenac have an important role in postoperative pain reduction at the spinal level, and that gabapentin augments the antihyperalgesic effects of diclofenac through action in the spinal cord.

Perioperative care for the older outpatient undergoing ambulatory surgery

As the number of ambulatory surgery procedures continues to grow in an aging global society, the implementation of evidence-based perioperative care programs for the elderly will assume increased importance. Given the recent advances in anesthesia, surgery, and monitoring technology, the ambulatory setting offers potential advantages for elderly patients undergoing elective surgery. In this review article we summarize the physiologic and pharmacologic effects of aging and their influence on anesthetic drugs, the important considerations in the preoperative evaluation of elderly outpatients with coexisting diseases, the advantages and disadvantages of different anesthetic techniques on a procedural-specific basis, and offer recommendations regarding the management of common postoperative side effects (including delirium and cognitive dysfunction, fatigue, dizziness, pain, and gastrointestinal dysfunction) after ambulatory surgery. We conclude with a discussion of future challenges related to the growth of ambulatory surgery practice in this segment of our surgical population. When information specifically for the elderly population was not available in the peer-reviewed literature, we drew from relevant information in other ambulatory surgery populations.

Strategies Aimed at Preventing Chronic Post-surgical Pain: Comprehensive Perioperative Pain Management after Total Joint Replacement Surgery

PURPOSE

Chronic post-surgical pain (CPSP) is a frequent outcome of musculoskeletal surgery. Physiotherapists often treat patients with pain before and after musculoskeletal surgery. The purposes of this paper are (1) to raise awareness of the nature, mechanisms, and significance of CPSP; and (2) to highlight the necessity for an inter-professional team to understand and address its complexity. Using total joint replacement surgeries as a model, we provide a review of pain mechanisms and pain management strategies.

SUMMARY OF KEY POINTS

By understanding the mechanisms by which pain alters the body's normal physiological responses to surgery, clinicians selectively target pain in post-surgical patients through the use of multi-modal management strategies. Clinicians should not assume that patients receiving multiple medications have a problem with pain. Rather, the modern-day approach is to manage pain using preventive strategies, with the aims of reducing the intensity of acute postoperative pain and minimizing the development of CPSP.

CONCLUSIONS

The roles of biological, surgical, psychosocial, and patient-related risk factors in the transition to pain chronicity require further investigation if we are to better understand their relationships with pain. Measuring pain intensity and analgesic use is not sufficient. Proper evaluation and management of risk factors for CPSP require inter-professional teams to characterize a patient's experience of postoperative pain and to examine pain arising during functional activities.

Preoperative gabapentin for acute post-thoracotomy analgesia: a randomized, double-blinded, active placebo-controlled study

BACKGROUND

The role of preoperative gabapentin in postoperative pain management is not clear, particularly in patients receiving regional blockade. Patients undergoing thoracotomy benefit from epidural analgesia but still may experience significant postoperative pain. We examined the effect of preoperative gabapentin in thoracotomy patients.

METHODS

Adults undergoing elective thoracotomy were enrolled in this prospective, randomized, double-blinded, placebo-controlled study, and randomly assigned to receive 600 mg gabapentin or active placebo (12.5 mg diphenhydramine) orally within 2 hours preoperatively. Standardized management included thoracic epidural infusion, intravenous patient-controlled opioid analgesia, acetaminophen and ketorolac. Pain scores, opioid use and side effects were recorded for 48 hours. Pain was also assessed at 3 months.

RESULTS

One hundred twenty patients (63 placebo and 57 gabapentin) were studied. Pain scores did not significantly differ at any time point (P = 0.53). Parenteral and oral opioid consumption was not significantly different between groups on postoperative day 1 or 2 (P > 0.05 in both cases). The frequency of side effects such as nausea and vomiting or respiratory depression was not significantly different between groups, but gabapentin was associated with decreased frequency of pruritus requiring nalbuphine (14% gabapentin vs. 43% control group, P < 0.001). The frequency of patients experiencing pain at 3 months post-thoracotomy was also comparable between groups (70% gabapentin vs. 66% placebo group, P = 0.72).

CONCLUSIONS

A single preoperative oral dose of gabapentin (600 mg) did not reduce pain scores or opioid consumption following elective thoracotomy, and did not confer any analgesic benefit in the setting of effective multimodal analgesia that included thoracic epidural infusion.

Multimodal pain management after total joint arthroplasty

Adequate postoperative pain control in patients who have undergone total joint arthroplasty allows faster rehabilitation and reduces the rate of postoperative complications. Multimodal pain management involves the introduction of adjunctive pain control methods in an attempt to control pain with less reliance on opioids and fewer side effects. Current research suggests that traditional nonsteroidal anti-inflammatory drugs (NSAIDs) and the associated cyclooxygenase type-2 (COX-2) inhibitors improve pain control in most cases. Nearly all multimodal pain management modalities have a safe side-effect profile when they are added to existing methods. The exception is the administration of DepoDur (extended-release epidural morphine) to elderly or respiratory-compromised patients because of a potential for hypoxia and cardiopulmonary events.

An enhanced bunionectomy model as a potential tool for early decision-making in the development of new analgesics

BACKGROUND

bunionectomy has been used as a model of postoperative pain for opioids and nonsteroidal anti-inflammatory drugs/cyclooxygenase-2 inhibitors with a fast onset of analgesia. The present study was conducted to assess whether the utility of the model can be broadened in assessing the efficacy of analgesics with diverse mechanisms and pharmacokinetic profiles in drug development and to enhance the sensitivity of a bunionectomy model.

METHODS

this was a single center, randomized, double-blind, placebo-controlled, three-arm, parallel group methodology study to evaluate the effects of pregabalin and naproxen sodium on postoperative pain following bunionectomy. Patients (n=100) were randomized 1:1:1 to three treatments (administered 1 hour before and at defined intervals after surgery): pregabalin 300 mg before surgery and 150 mg every 8 hours; naproxen sodium 550 mg before surgery and 550 mg every 12 hours; or placebo in a double-dummy fashion. Primary endpoints were patient-controlled analgesic (PCA) hydromorphone consumption and the time to first PCA hydromorphone use postsurgery over 24 hours.

RESULTS

of the 100 patients randomized, 96 completed the study. Relative to placebo, pregabalin and naproxen sodium, respectively, reduced PCA hydromorphone consumption by 51% (P=0.005) and 65% (P<0.001) and increased the median time to first use of PCA hydromorphone by 1.5 hours (P=0.004) and 3.7 hours (P<0.001). Both drugs significantly (P<0.050) decreased use of oral opioid rescue medication over 24-48 hours postsurgery relative to placebo. Although there were no statistically significant differences between naproxen sodium and pregabalin in opioid consumption and global evaluation of medication, overall naproxen sodium appeared to be more effective at reducing pain.

CONCLUSIONS

the model provided a sensitive method for evaluating efficacy of compounds with diverse mechanisms and pharmacokinetic profiles. The robustness of the enhanced pain model renders bunionectomy pain a valuable tool to assess novel analgesic compounds in small numbers of subjects early in drug development.

Molecular basis for the dosing time-dependency of anti-allodynic effects of gabapentin in a mouse model of neuropathic pain

BACKGROUND

Neuropathic pain is characterized by hypersensitivity to innocuous stimuli (tactile allodynia) that is nearly always resistant to NSAIDs or even opioids. Gabapentin, a GABA analogue, was originally developed to treat epilepsy. Accumulating clinical evidence supports the effectiveness of this drug for diverse neuropathic pain. In this study, we showed that the anti-allodynic effect of gabapentin was changed by the circadian oscillation in the expression of its target molecule, the calcium channel α2δ-1 subunit.

RESULTS

Mice were underwent partial sciatic nerve ligation (PSL) to create a model of neuropathic pain. The paw withdrawal threshold (PWT) in PSL mice significantly decreased and fluctuated with a period length about 24 h. The PWT in PSL mice was dose-dependently increased by intraperitoneal injection of gabapentin, but the anti-allodynic effects varied according to its dosing time. The protein levels of α2δ-1 subunit were up-regulated in the DRG of PSL mice, but the protein levels oscillated in a circadian time-dependent manner. The time-dependent oscillation of α2δ-1 subunit protein correlated with fluctuations in the maximal binding capacity of gabapentin. The anti-allodynic effect of gabapentin was attenuated at the times of the day when α2δ-1 subunit protein was abundant.

CONCLUSIONS

These findings suggest that the dosing time-dependent difference in the anti-allodynic effects of gabapentin is attributable to the circadian oscillation of α2δ-1 subunit expression in the DRG and indicate that the optimizing its dosing schedule helps to achieve rational pharmacotherapy for neuropathic pain.

Can gabapentin help reduce postoperative pain in arthroscopic rotator cuff repair? A prospective, randomized, double-blind study

PURPOSE

The aim of the study was to determine the effect of low-dose gabapentin on postoperative pain management in patients undergoing arthroscopic rotator cuff repair.

METHODS

This randomized, double-blinded, placebo-controlled study included 46 patients. The patients were divided into 2 groups according to the drug administered 2 hours before surgery, either 300 mg of gabapentin or placebo. The primary outcome measure was the visual analog scale (VAS) score at 2, 6, 12, and 24 hours postoperatively. The secondary outcome measures were fentanyl consumption and side effects during the first 2 hours in the postanesthesia care unit and then at 6 and 24 hours postoperatively. The patients were evaluated for side effects including nausea, vomiting, respiratory depression, dizziness, drowsiness, voiding difficulty, and pruritus.

RESULTS

The VAS scores at 2, 6, and 12 hours postoperatively were significantly lower in the gabapentin group than in the placebo group (P = .023, P = .019, and P = .022, respectively). The consumption of fentanyl, over a period of 24 hours, was not different in the comparisons between the groups (P = .686). The incidence of side effects was similar in the 2 groups.

CONCLUSIONS

A single dose of 300 mg of gabapentin reduced the VAS score during the first 24 hours postoperatively in patients undergoing shoulder arthroscopic rotator cuff repair, without significant side effects when compared with placebo. However, the fentanyl consumption did not differ between the gabapentin and placebo groups.

LEVEL OF EVIDENCE

Level I, randomized controlled trial.

Anti-Emetic Effect of Midazolam Added to Morphine Patient-Controlled Analgesia After Total Abdominal Hysterectomy

Nausea and vomiting are frequent adverse effects of patient-controlled analgesia with opioids. This study was designed to compare the effect of midazolam to that of ondansetron for prevention of nausea and vomiting during morphine patient-controlled analgesia. In a randomised, double-blind, prospective trial, 90 patients were allocated to one of three groups of 30 each, to receive one of three patient-controlled analgesia regimens to manage postoperative pain: a combination of midazolam and morphine (group M), a mixture of ondansetron and morphine (group O) or morphine alone (group C). Patients were assessed for the incidence of nausea and vomiting, the degree of sedation (awake, mild, moderate, deep) and other side-effects during the first 24 hours after the operation. The frequency of nausea and vomiting was significantly lower in groups M (27%) and O (37%) compared with group C (70%) (P <0.05). The incidence of mild sedation in group M was significantly higher than that in groups O or C (P <0.05). We conclude that midazolam is as effective as ondansetron in preventing opioid-induced nausea and vomiting following total abdominal hysterectomy and has acceptable side-effects.

Gabapentin decreases morphine consumption and improves functional recovery following total knee arthroplasty

BACKGROUND

Moderate to severe pain after total knee arthroplasty often interferes with postoperative rehabilitation and delays discharge from hospital. The present study examined the effects of a four-day postoperative gabapentin (GBP) regimen versus placebo on opioid consumption, pain scores and knee flexion, as well as adverse effects, after total knee arthroplasty.

METHODS

After obtaining research ethics board approval and informed consent, 40 patients were enrolled in a randomized, single-blind, placebo-controlled, open-label study. Patients were assigned to one of five groups - preoperative placebo/postoperative placebo (G1), preoperative GBP 600 mg/postoperative placebo (G2), preoperative GBP 600 mg/postoperative GBP 100 mg three times per day (G3), preoperative GBP 600 mg/ postoperative GBP 200 mg three times per day (G4) and preoperative GBP 600 mg/postoperative GBP 300 mg three times per day (G5). Postoperative GBP or placebo was continued for four days after surgery. Two hours before surgery, all patients received celecoxib 400 mg. Based on the above groupings, patients in G1 received placebo medication, whereas patients in G2, G3, G4 and G5 received gabapentin 600 mg 2 h preoperatively. All patients received femoral and sciatic nerve blocks, followed by spinal anesthesia. Beginning in the postanesthetic care unit, all patients received a regimen of celecoxib 200 mg every 12 h for four days and a patient-controlled morphine analgesia pump for 48 h.

RESULTS

Thirty-six patients (G1, n=7; G2, n=7; G3, n=8; G4, n=7; G5, n=7) completed the study. Data were analyzed by one-way ANOVA followed by a contrast comparing patients who received postoperative GBP (G3, G4 and G5) (n=22) with patients who received placebo postoperatively (G1 and G2) (n=14). Patients who received GBP postoperatively used significantly less patient-controlled morphine analgesia at 24 h, 36 h and 48 h (P<0.05). The postoperative GBP patients had significantly better active assisted knee flexion on postoperative days 2 and 3, with a trend toward better flexion on postoperative day 4. Patients who received GBP postoperatively reported less pruritus than patients who received placebo. There were no differences in pain scores.

CONCLUSIONS

These results support the use of GBP in the acute postoperative period. Further trials are needed to delineate the optimal dose, timing and duration of GBP use following 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.