The Analgesic Effects of Gabapentin in Monitored Anesthesia Care for Ear-Nose-Throat Surgery

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.

Focused local anesthesia and analgesia for head and neck surgery

Facility in the use of head and neck regional blocks will provide excellent perioperative analgesia and patient satisfaction. The scope of ambulatory surgical care for head and neck surgery will undoubtedly increase as expertize in these blocks expand in the face of strict criteria for patient selection. Supplemental sedation will be more precise with the intended result of less hangover and nausea and vomiting.

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.

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.

Single dose of preoperative analgesia with gabapentin (600 mg) is safe and effective in monitored anesthesia care for nasal surgery

This study was aimed to compare the intraoperative sedative and perioperative analgesic drug requirements and the incidences of postoperative side effects on the patients who received preoperative gabapentin or placebo. Sixty patients undergoing nasal septal or nasal sinus surgery were included. The patients received either 600 mg gabapentin (Group G) or placebo (Group P) orally, 1 h before surgery. The scores for sedation and pain were recorded at 5, 15, 30, 45 and 60 min, intraoperatively and at 30 min, 1, 2, 4, 6, 9, 12, 16, 20, 24 h, postoperatively. Sedation was achieved with an IV bolus of propofol and continuous infusion of remifentanil. There were significant differences between gabapentin and placebo groups with regard to total consumptions of remifentanil (171.42 + or - 68 vs. 219.17 + or - 95 microg, respectively; P = 0.033) and propofol (59.45 + or - 36.08 vs. 104.14 + or - 54.98 mg, respectively; P = 0.001). Group G patients had significantly lower intraoperative VAS scores at all time points (P < 0.05). The anxiety score of Group G was better at all times (P < 0.05). All postoperative pain scores were lower in the Group G (P < 0.05). Time to first request for analgesic was 12.7 + or - 2.3 h in Group G, and 7.8 2.1 h in Group P (P < 0.0001). Total consumption of lornoxicam was lower in Group G (P < 0.004). We concluded that monitored anesthesia care combined with preoperative analgesia with a low dose of (600 mg) oral gabapentin is an efficient option with tolerable side effects for patients undergoing ear, nose and throat ambulatory surgery.

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.

Multimodal analgesia for hip arthroplasty

Multimodal analgesia incorporates the use of analgesic adjuncts with different mechanisms of action to enhance postoperative pain management. Acetaminophen, anti-inflammatories, and gabapentinoids provide effective analgesia while reducing opioid requirements and opioid-related side effects. Intrathecal morphine and periarticular local anesthetic infiltration further enhance dynamic analgesia and improve postoperative mobilization. Epidural analgesia, peripheral nerve blocks, tramadol, ketamine, and/or clonidine can be added for improved benefit in opioid-tolerant individuals.

The median effective dose of preemptive gabapentin on postoperative morphine consumption after posterior lumbar spinal fusion

BACKGROUND

A single dose of preemptive gabapentin reduces postoperative pain and postoperative analgesic consumption. However, the optimal dose of preemptive gabapentin remains to be evaluated.

METHODS

In this prospective study, we defined the median effective analgesic dose using an up-and-down sequential allocation technique of preemptive gabapentin in 67 patients undergoing elective posterior lumbar spinal fusion. The efficacy of the study drug was assessed by morphine consumption during the first 24 h postoperatively.

RESULTS

The median effective analgesic dose (median value and 95% confidence interval) of gabapentin was 21.7 mg/kg (19.9-23.5 mg/kg).

CONCLUSION

Given the large dose of gabapentin needed, further powered studies are warranted to assess side effects.

Oral gabapentin for the treatment of postoperative pain after photorefractive keratectomy

PURPOSE

To evaluate oral gabapentin for postoperative pain after photorefractive keratectomy (PRK).

DESIGN

Prospective, nonrandomized clinical trial.

METHODS

In additional to a standard regimen of topical antibiotics, topical steroids, and topical tetracaine as required, all PRK patients at our laser vision center were treated after surgery for pain for a two-month period with Percocet (oxycodone/acetaminophen) [Endo Pharmaceuticals; Chadds Ford, Pennsylvania, USA] 5 mg/325 mg as required for three days (control group). Patients completed a pain assessment survey using a faces pain scale (from zero through 6) on the evening of surgery and each subsequent morning and evening until postoperative day 3. A successive cohort of patients received Neurontin (gabapentin) [Pfizer, New York, New York, USA] 300 mg thrice daily (first dose administered two hours or more before the procedure) as an oral pain medication for three days, and the same survey data were collected.

RESULTS

Data were collected on 141 patients in each cohort. Successful pain management score (defined as faces zero through 2 on the scale) differences did not reach statistical significance between the two cohorts except on the morning of the second postoperative day, when gabapentin was superior. On all postoperative days, patients in the oxycodone/acetaminophen cohort used significantly less tetracaine eye drops as required. The percent of patients rating overall pain experience as better than expected was 35% and 36%, those rating pain experience as about what was expected was 50% and 49%, and those rating pain experience as worse than expected was 15% and 15% in the oxycodone/acetaminophen and gabapentin cohorts, respectively.

CONCLUSIONS

We found no difference in overall subjective pain management ratings between gabapentin and oxycodone/acetaminophen for postoperative PRK pain, although gabapentin was associated with significantly more frequent use of anesthetic eye drops as required.

Gabapentin reduces cardiovascular responses to laryngoscopy and tracheal intubation

BACKGROUND AND OBJECTIVE

We have compared the effects of gabapentin on arterial pressure and heart rate at induction of anaesthesia and tracheal intubation in a randomized double-blind study.

METHODS

Ninety normotensive patients (ASA I) undergoing elective surgery were divided into three groups of 30 patients each. Patients received oral placebo (Group I), 400 mg of gabapentin (Group II) or 800 mg of gabapentin (Group III) 1 h prior to surgery in the operating theatre. After induction of anaesthesia heart rate and mean arterial pressure were recorded at baseline 1, 3, 5, 10 and 15 min after intubation.

RESULTS

Patients receiving placebo and 400 mg gabapentin showed a significant increase in blood pressure and heart rate associated with tracheal intubation compared to baseline levels and Group III. There was significant decrease in heart rate and arterial pressure in Group III after intubation 1, 3, 5 and 10 min (P < 0.001, P < 0.001, P < 0.05 and P < 0.05, respectively) compared to Groups I and II.

CONCLUSION

Given 1 h before operation gabapentin 800 mg blunted the arterial pressure and heart rate increase in first 10 min due to endotracheal intubation. Oral administration of gabapentin 800 mg before induction of anaesthesia is a simple and practical method for attenuating pressor response to laryngoscopy and tracheal intubation after standard elective induction.

The preoperative use of gabapentin, dexamethasone, and their combination in varicocele surgery: a randomized controlled trial

BACKGROUND

We investigated the effects of gabapentin and dexamethasone given together or separately 1 h before the start of surgery on laryngoscopy, tracheal intubation, intraoperative hemodynamics, opioid consumption, and postoperative pain in patients undergoing varicocele operations.

METHODS

Patients were randomly divided into four double-blind groups: group C (control, n = 20) received placebo, group G (gabapentin, n = 20) received 800 mg gabapentin, group D (dexamethasone, n = 20) received 8 mg dexamethasone, group GD (gabapentin plus dexamethasone) received both 800 mg gabapentin and 8 mg dexamethasone IV 1 h before the start of surgery. Standard induction and maintenance of anesthesia were accomplished and continued by propofol and remifentanil infusion. Heart rate and arterial blood pressure were recorded before induction and after intubation. Intraoperative total remifentanil consumption was recorded. Hemodynamic variables and visual analog scale were recorded for 24 h. Side effects were noted.

RESULTS

Hemodynamics at 1, 3, 5, and 10 min after tracheal intubation, total remifentanil consumption during surgery, postoperative visual analog scale scores at 30 min, 1, 2, 4, 6, and 12 h, and postoperative nausea and vomiting were found to be significantly lower in group GD than in group G and group D (P < 0.05 for both), and substantially lower when compared with group C (P < 0.001). All values in group C were also higher than in groups G and D (P < 0.05).

CONCLUSION

Gabapentin and dexamethasone administered together an hour before varicocele surgery results in less laryngeal and tracheal intubation response, improves postoperative analgesia, and prevents postoperative nausea and vomiting better than individual administration of each drug.

Gabapentin and pregabalin for chronic neuropathic and early postsurgical pain: current evidence and future directions

PURPOSE OF REVIEW

Gabapentin and pregabalin bind to the alpha-2-delta calcium channel subunit and represent a novel analgesic drug class. The evidence base supporting their use for chronic neuropathic and early postsurgical pain is reviewed.

RECENT FINDINGS

Multiple, large, high-quality trials have demonstrated the safety and efficacy of gabapentin and pregabalin in neuropathic pain. Treatment-related improvement of pain and sleep positively impact upon quality of life. Sedation, dizziness and ataxia are important and relatively common adverse effects, however. Accumulating evidence indicates that gabapentin, and possibly pregabalin, also exert important effects following surgery. Multiple high-quality trials have demonstrated analgesic and opioid-sparing efficacy with gabapentin following various surgical procedures. Gabapentin and pregabalin reduce movement-evoked pain and this can lead to enhanced functional postoperative recovery. Postoperative opioid sparing is of questionable relevance since few trials have shown reduced opioid-related adverse effects. Sedation, dizziness and ataxia have been reported in only a few trials. Future larger-scale perioperative trials focused on safety assessment are needed, however.

SUMMARY

Gabapentin and pregabalin are efficacious treatments for neuropathic and postsurgical pain. Future research addressing several specific questions would serve to better delineate their optimal roles in treating these and other pain conditions.

Use of gabapentin for perioperative pain control -- a meta-analysis

BACKGROUND

Gabapentin, an anticonvulsant, has recently been suggested as an effective postoperative 'analgesic' agent. The objective of the present study was to examine the analgesic effectiveness, opioid-sparing effects and side effects associated with the use of gabapentin in a perioperative setting.

METHODS

Following the Quality of Reporting of Meta-analyses recommendations, nine electronic databases until February 2006 were searched, without language restriction, for randomized controlled trials comparing gabapentin with control for postoperative pain control. Outcome measures, namely, 24 h cumulative opioid consumption, visual analogue scale pain scores and adverse effects, were expressed as odds ratios, ratio of means or weighted mean differences (as appropriate), which were aggregated under the fixed or random effects models.

RESULTS

Gabapentin caused a 35% reduction in total opioid consumption over the first 24 h following surgery (ratio of means 0.65, 95% CI 0.59 to 0.72), a significant reduction in postoperative pain at rest (in the first 24 h) and with movement (at 2 h, 4 h and 12 h), regardless of whether treatment effects were expressed as ratios of means or weighted mean differences, and a reduction of vomiting (relative risk [RR] 0.73, 95% CI 0.56 to 0.95) and pruritus (RR 0.30, 95% CI 0.13 to 0.70). It was associated with a significant increase in dizziness (RR 1.40, 95% CI 1.06 to 1.84) and an increase in sedation of borderline significance (RR 1.65, 95% CI 1.00 to 2.74).

CONCLUSION

Gabapentin improves the analgesic efficacy of opioids both at rest and with movement, reduces analgesic consumption and opioid-related adverse effects, but is associated with an increased incidence of sedation and dizziness.

Gabapentin and postoperative pain: a qualitative and quantitative systematic review, with focus on procedure

Background

Gabapentin is an antiepileptic drug used in a variety of chronic pain conditions. Increasing numbers of randomized trials indicate that gabapentin is effective as a postoperative analgesic. This procedure-specific systematic review aims to analyse the 24-hour postoperative effect of gabapentin on acute pain in adults.

Methods

Medline, The Cochrane Library and Google Scholar were searched for double-blind randomized placebo controlled trials of gabapentin for postoperative pain relief compared with placebo, in adults undergoing a surgical procedure.

Qualitative analysis of postoperative effectiveness was evaluated by assessment of significant difference (P < 0.05) in pain relief using consumption of supplemental analgesic and pain scores between study groups.

Quantitative analyses of combined data from similar procedures, were performed by calculating the weighted mean difference (WMD) of 24-hour cumulated opioid requirements, and the WMD for visual analogue scale (VAS) pain, (early (6 h) and late (24 h) postoperatively), between study groups. Side-effects (nausea, vomiting, dizziness and sedation) were extracted for calculation of their relative risk (RR).

Results

Twenty-three trials with 1529 patients were included. In 12 of 16 studies with data on postoperative opioid requirement, the reported 24-hour opioid consumption was significantly reduced with gabapentin. Quantitative analysis of five trials in abdominal hysterectomy showed a significant reduction in morphine consumption (WMD – 13 mg, 95% confidence interval (CI) -19 to -8 mg), and in early pain scores at rest (WMD – 11 mm on the VAS, 95% CI -12 to -2 mm) and during activity (WMD -8 mm on the VAS; 95% CI -13 to -3 mm), favouring gabapentin. In spinal surgery, (4 trials), analyses demonstrated a significant reduction in morphine consumption (WMD of – 31 mg (95%CI – 53 to -10 mg) and pain scores, early (WMD – 17 mm on the VAS; 95 % CI -31 to -3 mm) and late (WMD -12 mm on the VAS; 95% CI -23 to -1 mm) also favouring gabapentin treatment. Nausea was improved with gabapentin in abdominal hysterectomy (RR 0.7; 95 % CI 0.5 to 0.9). Other side-effects were unaffected.

Conclusion

Perioperative use of gabapentin has a significant 24-hour opioid sparing effect and improves pain score for both abdominal hysterectomy and spinal surgery. Nausea may be reduced in abdominal hysterectomy.

Do Surgical Patients Benefit from Perioperative Gabapentin/Pregabalin? A Systematic Review of Efficacy and Safety

BACKGROUND

Gabapentin and pregabalin have antiallodynic and antihyperalgesic properties useful for treating neuropathic pain. These properties may also be beneficial in acute postoperative pain. In this study we evaluated randomized, controlled trials examining the analgesic efficacy, adverse effects, and clinical value of gabapentinoids in postoperative pain.

METHODS

A systematic search of Medline, PubMed, and Cochrane Central Register of Controlled Trials (CENTRAL) databases yielded 22 randomized, controlled trials on perioperative administration of gabapentinoids for postoperative pain relief.

RESULTS

Pain relief was better in the gabapentin groups compared with the control groups. The opioid-sparing effect during the first 24 h after a single dose of gabapentin 300-1200 mg, administered 1-2 h preoperatively, ranged from 20% to 62%. The combined effect of a single dose of gabapentin was a reduction of opioid consumption equivalent to 30 +/- 4 mg of morphine (mean +/- 95% CI) during the first 24 h after surgery. Metaregression analysis suggested that the gabapentin-induced reduction in the 24-h opioid consumption was not significantly dependent on the gabapentin dose. Gabapentin reduced opioid-related adverse effects, such as nausea, vomiting, and urinary retention (number-needed-to-treat 25, 6, and 7, respectively). The most common adverse effects of the gabapentinoids were sedation and dizziness (number-needed-to-harm 35 and 12, respectively).

CONCLUSIONS

Gabapentinoids effectively reduce postoperative pain, opioid consumption, and opioid-related adverse effects after surgery. Conclusions about the optimal dose and duration of the treatment cannot be made because of the heterogeneity of the trials. Studies are needed to determine the long-term benefits, if any, of perioperative gabapentinoids.

Perioperative pain management

The under-treatment of postoperative pain has been recognised to delay patient recovery and discharge from hospital. Despite recognition of the importance of effective pain control, up to 70% of patients still complain of moderate to severe pain postoperatively. The mechanistic approach to pain management, based on current understanding of the peripheral and central mechanisms involved in nociceptive transmission, provides newer options for clinicians to manage pain effectively. In this article we review the rationale for a multimodal approach with combinations of analgesics from different classes and different sites of analgesic administration. The pharmacological options of commonly used analgesics, such as opioids, NSAIDs, paracetamol, tramadol and other non-opioid analgesics, and their combinations is discussed. These analgesics have been shown to provide effective pain relief and their combinations demonstrate a reduction in opioid consumption. The basis for using non-opioid analgesic adjuvants is to reduce opioid consumption and consequently alleviate opioid-related adverse effects. We review the evidence on the opioid-sparing effect of ketamine, clonidine, gabapentin and other novel analgesics in perioperative pain management. Most available data support the addition of these adjuvants to routine analgesic techniques to reduce the need for opioids and improve quality of analgesia by their synergistic effect. Local anaesthetic infiltration, epidural and other regional techniques are also used successfully to enhance perioperative analgesia after a variety of surgical procedures. The use of continuous perineural techniques that offer prolonged analgesia with local anaesthetic infusion has been extended to the care of patients beyond hospital discharge. The use of nonpharmacological options such as acupuncture, relaxation, music therapy, hypnosis and transcutaneous nerve stimulation as adjuvants to conventional analgesia should be considered and incorporated to achieve an effective and successful perioperative pain management regimen.

Premedication with gabapentin: the effect on tourniquet pain and quality of intravenous regional anesthesia

BACKGROUND

Gabapentin, an oral non-opioid analgesic, has been used to decrease pain after a variety of surgical procedures. We hypothesized that premedication with gabapentin would minimize tourniquet-related pain in patients receiving IV regional anesthesia (IVRA).

METHODS

Patients undergoing elective hand surgery with IVRA were randomly assigned to one of two study groups using a double-blind study design. The control group (n = 20) received placebo capsules 1 h before the surgery, and the gabapentin group (n = 20) received gabapentin 1.2 g p.o. before the operation. IVRA was achieved in all patients with lidocaine, 3 mg/kg, diluted with saline to a total volume of 40 mL. Fentanyl, 0.5 microg/kg IV, was administered as a rescue analgesic during surgery. Sensory and motor block onset and recovery times, tourniquet pain, and quality of anesthesia were assessed at specific time intervals during the perioperative period. Visual analog scale pain scores (0-10) were recorded during the 24 h follow-up period, and patients received diclofenac, 75 mg IM, if their pain score was >4.

RESULTS

The onset of the sensory and motor block did not differ between the two study groups. However, tourniquet pain scores at 30, 40, 50, and 60 min after cuff inflation were lower in the gabapentin group (P < 0.05). The time to intraoperative analgesic rescue was prolonged in the gabapentin group (35 +/- 10 min vs 21 +/- 13 min, P < 0.05), and less supplemental fentanyl was required (35 +/- 47 microg vs 83 +/- 73 microg, P < 0.05). The quality of anesthesia, as independently assessed by the anesthesiologist and the surgeon, was significantly better in the gabapentin (versus control) group. In the gabapentin group, the time to requesting a rescue analgesic after surgery was prolonged (135 +/- 25 min vs 85 +/- 19 min, P < 0.05), and postoperative pain scores at 60 min (3.8 +/- 0.9 vs 2.2 +/- 0.5) and 120 min (3.2 +/- 1.4 vs 1.8 +/- 0.8), as well as diclofenac consumption (30 +/- 38 mg vs 60 +/- 63 mg), were reduced after surgery.

CONCLUSIONS

Premedication with oral gabapentin (1.2 g) decreased tourniquet-related pain and improved the quality of anesthesia during hand surgery under IVRA. Gabapentin also reduced pain scores in the early postoperative period.

Gabapentin and postoperative pain – a systematic review of randomized controlled trials

The objective of this systematic review was to evaluate the efficacy and tolerability of perioperative gabapentin administration for the control of acute postoperative pain. We searched Medline (1966-2006), the Cochrane Library (2006), Scopus, CINAHL and bibliographies from clinical trials and review articles. We included randomized controlled trials (RCTs) comparing gabapentin with inactive controls in surgical patients. Sixteen valid RCTs were included. Weighted mean difference (WMD) for postoperative pain intensity (0-100 mm visual analogue scale) was -16.55 mm at 6 h and -10.87 mm at 24 h for treatment with a single preoperative dose of gabapentin 1200 mg. Cumulative opioid consumption at 24 h was also significantly decreased with gabapentin (WMD, -27.90 mg). When gabapentin was administered at doses less than 1200 mg, pain intensity was also lower at 6 h (WMD, -22.43 mm) and 24 h (WMD, -13.18 mm). Cumulative 24 h opioid consumption was also lower (WMD, -7.25 mg). Gabapentin was associated with an increased risk of sedation (Peto OR 3.86; 95% CI 2.50-5.94) but less opioid-related side effects such as vomiting (Peto OR 0.58; 95% CI 0.39-0.86) and pruritus (Peto OR 0.27; 95% CI 0.10-0.74). In conclusion, gabapentin has an analgesic and opioid-sparing effect in acute postoperative pain management when used in conjunction with opioids.

Effect of Gabapentin on morphine demand and pain after laparoscopic sterilization using Filshie clips. A double blind randomized clinical trial

Background

A considerable number of patients require opioids during recovery after laparoscopic sterilization. This implies nausea, dizziness and sedation and increases the number of unplanned admissions. Gabapentin has shown excellent postoperative analgesic effect in a number of recent studies with few side effects. This study was designed to test whether gabapentin given preoperatively can reduce the number of patients needing morphine in the recovery period.

Methods

80 females scheduled for laparoscopic sterilization using Filshie clips were randomized to two treatment groups (Gaba group and control group).

All patients received lornoxicam 8 mg p.o. 30 min. before the procedure. Patients in the Gaba group received gabapentin 1200 mg p.o. and patients in the control group received placebo capsules prior to the procedure. All patients were anesthetized according to a protocol, using remifentanil and propofol.

Postoperative analgesia was obtained with patient controlled infusion of morphine. Pain, nausea, dizziness and sedation were scored at 2 and 4 hours after end of anesthesia. The expenditure of morphine was the primary measure for the effect of analgesia and the number of patients demanding morphine was the primary endpoint.

Results

Three patients were excluded because of procedural errors and one because of conversion to open surgery. 38 patients completed the study in each group.

32 (84%) patients in the gabapentin group and 37 (97%) patients in the control group did require morphine in the recovery period. (p = 0,049).

There was no significant difference between mean morphine consumption, pain scores and frequency of adverse effects (nausea, dizziness, sedation and vomiting)

Conclusion

The postoperative analgesic effect of gabapentin given preoperatively was confirmed in this study. For this procedure, with pain predominantly in the immediate recovery period, and of less intensity than after major surgical procedures, the effect demonstrated is much less pronounced than in similar studies of major surgery. General use of gabapentin as analgesic for laparoscopic sterilization is not supported by this study.

Trial Registration

Current Controlled Trials ISCRTN39209275

A Single Preoperative Dose of Gabapentin (800 Milligrams) Does Not Augment Postoperative Analgesia in Patients Given Interscalene Brachial Plexus Blocks for Arthroscopic Shoulder Surgery

BACKGROUND

Inadequate analgesia is common after shoulder arthroscopy. Both interscalene blocks and gabapentin are effective methods of pain management under various circumstances. We tested the hypothesis that gabapentin augments postoperative analgesia provided by interscalene brachial plexus block in patients having ambulatory arthroscopic shoulder surgery.

METHODS

Sixty patients were randomly assigned to receive oral gabapentin, 800 mg, or placebo 2 h before surgery. An interscalene brachial plexus block with 0.3 mL/kg of 0.5% ropivacaine was performed. General anesthesia was maintained with sevoflurane and included a single 1-microg/kg dose of remifentanil. Postoperative analgesia was initially provided with morphine and subsequently with ketoprofene (150 mg orally twice daily) and a combination of 400 mg acetaminophen and 30 mg dextropropoxyphene as needed. Pain scores, analgesic requirements, and side effects were assessed in the ambulatory unit and at home for 48 h.

RESULTS

Emergence from general anesthesia was similar in both groups. There were no significant differences in pain scores, first postoperative request for analgesia, or oral analgesic consumption. The incidence of side effects was comparable in both groups, except that headaches were less frequent in the gabapentin group.

CONCLUSION

A single preoperative dose of gabapentin (800 mg) does not augment postoperative analgesia in patients given interscalene brachial plexus blocks for arthroscopic shoulder surgery.

Pre-emptive analgesia and protective premedication. What is the difference?

The management of postoperative pain has been greatly informed by an increasing understanding of the basic science of pain transmission. The idea that analgesia given before the injury would be more effective than the same analgesia given after the injury was named pre-emptive analgesia. The evidence for this phenomenon in postoperative pain management has been very mixed. The methodological problems of such studies, and the difficulties of all the major outcome measures make comparison of the studies available difficult. In the 20 years since the concept was proposed there has been a change in anaesthetic practice that in effect incorporates pre-emptive analgesia with opiates. Evidence for any pre-emptive analgesic with non-steroidal anti-inflammatory drugs is very poor, but the use of local anaesthetic blocks continues to be an area of study. Pre-emptive use of analgesic drugs is not the magic bullet to prevent postoperative pain, but is a strategy of use, among others for managing postoperative pain. Protective analgesia is a strategy that has grown out of the same desire to give drugs before injury to reduce the pain experienced afterwards. In this case the drugs under study have not been primary analgesics, but adjuvant drugs used commonly in the non-acute pain arena. In particular, the drug gabapentin, and to a lesser extent its related drug pregabalin. These drugs have been given by mouth as a pre-medicant, 1 hour before surgery in a variety of operations. A recent meta-analysis of the existing literature shows reduction of postoperative morphine consumption but little reduction in reporting of opiate side effects. Pregabalin, which has a better pharmacokinetic profile, may be a better alternative, and is currently under study. Neither gabapentin nor pregabalin are licensed for use in postoperative pain, and it is unlike that the manufacturers will seek such a licence.

The effect of gabapentin on post-operative pain following tonsillectomy in adults

BACKGROUND

The aim of the present study was to investigate whether a combination of rofecoxib and gabapentin could improve pain relief and reduce opioid requirements, compared with rofecoxib alone, during the first 5 days after tonsillectomy.

METHODS

In a randomized, double-blind, placebo-controlled study, 49 patients received gabapentin 1200 mg pre-operatively, followed by gabapentin 2 x 600 mg on the day of operation and gabapentin 3 x 600 mg for the next 5 days, or placebo. Both groups were given rofecoxib 50 mg daily. In the post-operative care unit, intravenous morphine was administered in doses of 2.5 mg on request. From 4 h to 5 days post-operatively, ketobemidone was offered as escape drug. Pain at rest and during swallowing, and side-effects, were assessed using a four-point verbal rating scale.

RESULTS

As a result of the global withdrawal of rofecoxib, the study had to be terminated prematurely. This report comprises the results from 22 patients in the gabapentin group and 27 patients in the placebo group. Gabapentin reduced ketobemidone requirements during the first 24 h post-operatively [4.5 mg (standard deviation, 3.0 mg) in the placebo group vs. 2.0 mg (standard deviation, 2.0 mg) in the gabapentin group; P < 0.003]. Gabapentin induced more dizziness (P < 0.002), gait disturbance (P < 0.02) and vomiting (P < 0.05) during days 0-5 than placebo. No other statistically significant differences were observed.

CONCLUSION

Gabapentin reduced opioid requirements in the first 24 h after tonsillectomy. The benefits of the reduced opioid intake may be overshadowed by the drawbacks of side-effects.

Review article: The role of anticonvulsant drugs in postoperative pain management: a bench-to-bedside perspective

PURPOSE

Anticonvulsant drugs are effective in the treatment of chronic neuropathic pain but were not, until recently, thought to be useful in more acute conditions such as postoperative pain. However, similar to nerve injury, surgical tissue injury is known to produce neuroplastic changes leading to spinal sensitization and the expression of stimulus-evoked hyperalgesia and allodynia. Pharmacological effects of anticonvulsant drugs which may be important in the modulation of these postoperative neural changes include suppression of sodium channel, calcium channel and glutamate receptor activity at peripheral, spinal and supraspinal sites. The purpose of this article is to review preclinical evidence and clinical trial data describing the efficacy and safety of anticonvulsant drugs in the setting of postoperative pain management.

SOURCE

A Medline search was performed to retrieve available literature on the basic and clinical pharmacology of anticonvulsant drugs as they pertain to postoperative pain management.

PRINCIPAL FINDINGS

Numerous laboratory studies have described analgesic effects of different anticonvulsant drugs in experimental pain models. Furthermore, several recent clinical trials have shown that anticonvulsants may reduce spontaneous and movement-evoked pain, as well as decrease opioid requirements postoperatively. Some early findings suggest further that anticonvulsant drugs may alleviate postoperative anxiety, accelerate postoperative functional recovery and reduce chronic postsurgical pain.

CONCLUSION

Given the incomplete efficacy of currently available non-opioid analgesics, and the identified benefits of opioid sparing, anticonvulsant medications may be useful adjuncts for postoperative analgesia. Further research in this field is warranted.

Effect of oral gabapentin on postoperative epidural analgesia †

BACKGROUND

Gabapentin has been used successfully as a non-opioid analgesic adjuvant for postoperative pain management. We hypothesized that gabapentin might be a useful adjuvant for postoperative analgesia provided with patient-controlled epidural analgesia (PCEA).

METHODS

Forty patients undergoing lower extremity surgery procedures were randomly assigned to receive (i) placebo capsules (control) or (ii) gabapentin (1.2 g day(-1)) before and for 2 days after surgery. Anaesthetic technique was standardized. Postoperative assessments included verbal rating scale scoring for pain and sedation, PCEA usage, quality of recovery assessment, times of GI function recovery, and patient satisfaction scoring for pain management.

RESULTS

Pain scores at 1, 4, 8, 12, and 16 h (P<0.001), PCEA bolus requirements (n) at 24 [21 (3), 14 (2)], 48 [15 (4), 10 (3)] and 72 [8 (5), 2 (3)] (P<0.05) and paracetamol (mg) consumption [700 (523), 350 (400)]; P<0.05), were significantly lower in the gabapentin-treated patients than in the control group. Patient satisfaction with postoperative pain management at 24 h was better in gabapentin-treated patients [85.5 (7.5), 66.5 (15)]; P<0.001). Gabapentin-treated patients had less motor block when compared with control group. Times of return of bowel function, hospitalization, and resumption of dietary intake were similar in the groups. However, the incidence of dizziness was higher in the gabapentin group (35% vs 5%; P<0.05).

CONCLUSIONS

Oral gabapentin (1.2 g day(-1)) as an adjunct to epidural analgesia decreased pain and analgesic consumption. Despite an increased incidence of dizziness it also increased patient satisfaction.

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

The cyclooxygenase-2 inhibitor, rofecoxib, was a popular analgesic adjuvant for improving perioperative pain management. We designed this placebo-controlled study to test the hypothesis that gabapentin could produce similar reductions in postoperative pain and opioid analgesic usage, thereby improving the recovery process. One hundred patients undergoing abdominal hysterectomy procedures were randomly assigned to one of four treatment groups: 1) control group received placebo capsules and pills before and for 2 days after surgery, 2) rofecoxib group received 50 mg/d PO and placebo capsules before and after surgery and, 3) gabapentin group received 1.2 g/d PO and placebo pills before and after surgery, and 4) combination group received rofecoxib 50 mg/d and gabapentin 1.2 g/d PO before and after surgery. The anesthetic technique was standardized and the postoperative assessments included verbal rating scales for pain and sedation, IV morphine usage, quality of recovery assessment, recovery of bowel function, resumption of normal activities, and patient satisfaction with their pain management. Postoperative pain scores were significantly reduced in all three analgesic treatment groups (versus control group). Compared with the control group, patient-controlled analgesia morphine usage was also significantly reduced in the 3 analgesic treatment groups at 1, 8, 24, and 30 h after surgery. Total PCA morphine usage was decreased by 43%, 24%, and 50% in groups 2, 3, and 4, respectively, compared with group 1. Oral analgesic consumption was also smaller in groups 2 and 4 when compared with the control group. The opioid-sparing effects of rofecoxib and gabapentin lead to a faster recovery of bowel function. Discharge eligibility scores in groups 2 and 4 were improved at 24 h when compared with group 1, and patient satisfaction with postoperative pain management was significantly higher at 24 h in all 3 analgesic treatment groups. At the 72 h follow-up, all of the patients in group 4 were completely satisfied with their pain management compared with only 32%, 64%, and 72% in groups 1, 2, and 3, respectively. Gabapentin (1.2 g/d PO) appears to be an acceptable alternative to rofecoxib (50 mg/d PO) for short-term use as an adjuvant to opioid analgesics in patients undergoing lower abdominal surgery.

Pregabalin for Pain Management

Pregabalin is a new analog of the neurotransmitter gamma-aminobutyric acid (GABA). It is an alpha2-delta (alpha2-delta) ligand that has analgesic, anticonvulsant, and anxiolytic activity. Alpha2-delta is an auxiliary protein associated with voltage-gated calcium channels. Pregabalin binds potently to the alpha2-delta subunit resulting in modulation of calcium channels and reduction in the release of several neurotransmitters, including glutamate, norepinephrine, serotonin, dopamine, and substance P. This review discusses the pharmacology of this medication as well as available studies in patients.

Preoperative gabapentin decreases anxiety and improves early functional recovery from knee surgery

Gabapentin has antihyperalgesic and anxiolytic properties. We thus tested the hypothesis that premedication with gabapentin would decrease preoperative anxiety and improve postoperative analgesia and early postoperative knee mobilization in patients undergoing arthroscopic anterior cruciate ligament repair under general anesthesia. Forty patients were randomly assigned to receive 1200 mg oral gabapentin or placebo 1-2 h before surgery; anesthesia was standardized. Patients received morphine, 0.1 mg/kg, 30 min before the end of surgery and postoperatively via a patient-controlled pump. Pain scores and morphine consumption were recorded over 48 h. Degrees of active and passive knee flexion and extension were recorded during physiotherapy on days 1 and 2. Preoperative anxiety scores were less in the gabapentin than control group (visual analog scale scores of 28 +/- 16 mm versus 66 +/- 15 mm, respectively; P < 0.001). The gabapentin group required less morphine than the control group (29 +/- 22 mg versus 69 +/- 40 mg, respectively; P < 0.001). Visual analog scale pain scores at rest and after mobilization were significantly reduced in the gabapentin group. First and maximal passive and active knee flexions at 24 and 48 h were significantly more extensive in the gabapentin than in the control group. In conclusion, premedication with 1200 mg gabapentin improved preoperative anxiolysis, postoperative analgesia, and early knee mobilization after arthroscopic anterior cruciate ligament repair.

Evaluation of the Optimal Preemptive Dose of Gabapentin for Postoperative Pain Relief After Lumbar Diskectomy

We evaluated the optimal preemptive dose of gabapentin for postoperative pain relief after single-level lumbar diskectomy and its effect on fentanyl consumption during the initial 24 hours in a randomized, double-blinded, placebo-controlled study in 100 patients with American Society of Anesthesiologists physical status I and II. Patients were divided into five groups to receive placebo or gabapentin 300, 600, 900, or 1200 mg 2 hours before surgery. After surgery, patients were transferred to the postanesthesia care unit (PACU). A blinded anesthesiologist recorded the pain scores at time points of 6, 12, 18, and 24 hours in the PACU on a Visual Analog Scale (VAS; 0-10 cm) at rest. Patients received patient-controlled analgesia (fentanyl 1.0 mug/kg on each demand with lockout interval of 10 minutes); total fentanyl consumption during initial 24 hours was recorded. Data were entered into the statistical software package SPSS 9.0 for analysis (one-way analysis of variance and Student-Newman-Keuls test). Patients who received gabapentin 300 mg had significantly lower VAS score at all time points. They consumed less fentanyl (patients who received placebo processed 1217.5 +/- 182.0 versus 987.5 +/- 129.6 mug; P < 0.05). Patients who received gabapentin 600, 900, and 1200 mg had lower VAS scores at all time points than patients who received gabapentin 300 mg (P < 0.05). Increasing the dose of gabapentin from 600 to 1200 mg did not decrease the VAS score, nor did the increasing dose of gabapentin significantly decrease fentanyl consumption (702.5, 635, and 626.5 microg). Thus, gabapentin 600 mg is the optimal dose for postoperative pain relief following lumbar diskectomy.

Role of Analgesic Adjuncts in Postoperative Pain Management

Postoperative pain remains a major problem. A multi-modal analgesic approach is recommended to optimize pain management and reduce opiate-related adverse effects. Several analgesic adjuncts have been investigated, and many have proved to have a useful analgesic effect. This article reviews the literature regarding use of analgesic adjuncts in the perioperative period.