Mechanisms of Action by Which Local Anesthetics Reduce Cancer Recurrence: A Systematic Review

BACKGROUND

Surgery in concert with anesthesia is a key part of the management of advanced-stage cancers. Anesthetic agents such as opioids and volatile anesthetics have been shown to promote recurrence in preclinical models, whereas some animal models have shown that the use of lidocaine may be beneficial in reducing cancer recurrence. The purpose of this article is to review the current literature to highlight the mechanisms of action by which local anesthetics are thought to reduce cancer recurrence.

METHODS

A systematic review was conducted using the PubMed (1966 to 2018) electronic database. Search terms included "lidocaine," "ropivicaine," "procaine," "bupivicaine," "mepivicaine," "metastasis," "cancer recurrence," "angiogenesis," and "local anesthetics" in various combinations. The search yielded 146 total abstracts for initial review, 20 of which met criteria for inclusion. Theories for lidocaine's effect on cancer recurrence were recorded. All studies were reviewed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

RESULTS

Numerous mechanisms were proposed based on the local anesthetic used and the type of cancer. Mechanisms include those that are centered on endothelial growth factor receptor, voltage-gated sodium and calcium channels, transient receptor melanoplastin 7, hyperthermia, cell cycle, and demyelination.

CONCLUSIONS

In vivo models suggest that local anesthetic administration leads to reduced cancer recurrence. The etiology of this effect is likely multifactorial through both inhibition of certain pathways and direct induction of apoptosis, a decrease in tumor migration, and an association with cell cycle-mediated and DNA-mediated effects. Additional research is required to further define the clinical implications.

Effect of perioperative intravenous lidocaine for patients undergoing spine surgery: A meta-analysis and systematic review

BACKGROUND

Perioperative intravenous lidocaine has been reported to have analgesic and opioid-sparing effects in many kinds of surgery. Several studies have evaluated its use in the settings of spine surgery. The aim of the study is to examine the effect of intravenous lidocaine in patients undergoing spine surgery.

METHODS

We performed a quantitative systematic review. Databases of PubMed, Medline, Embase database and Cochrane library were investigated for eligible literatures from their establishments to June, 2019. Articles of randomized controlled trials that compared intravenous lidocaine to a control group in patients undergoing spine surgery were included. The primary outcome was postoperative pain intensity. Secondary outcomes included postoperative opioid consumption and the length of hospital stay.

RESULT

Four randomized controlled trials with 275 patients were included in the study. postoperative pain compared with control was reduced at 6 hours after surgery (WMD -0.50, 95%CI, -0.76 to -0.25, P < .001), at 24 hours after surgery (WMD -0.50, 95%CI, -0.70 to -0.29, P < .001) and at 48 hours after surgery (WMD -0.57, 95%CI, -0.96 to -0.17, P = .005). The effect of intravenous lidocaine on postoperative opioid consumption compared with control revealed a significant effect (WMD -15.36, 95%CI, -21.40 to -9.33 mg intravenous morphine equivalents, P < .001).

CONCLUSION

This quantitative analysis of randomized controlled trials demonstrated that the perioperative intravenous lidocaine was effective for reducing postoperative opioid consumption and pain in patients undergoing spine surgery. The intravenous lidocaine should be considered as an effective adjunct to improve analgesic outcomes in patients undergoing spine surgery. However, the quantity of the studies was very low, more research is needed.

Comparison of Perioperative Systemic Lidocaine or Systemic Ketamine in Acute Pain Management of Patients With Opioid Use Disorder After Orthopedic Surgery

INTRODUCTION AND AIMS

Patients with opioid use disorder experience great challenges during acute pain management due to opioid tolerance or withdrawal symptoms. Previous studies have recommended the use of adjuvant drugs in these patients. In this study, we compared the effect of intraoperative lidocaine with ketamine in postoperative pain management of these patients.

DESIGN AND METHODS

In this randomized clinical trial, 180 patients with opioid use disorder who underwent orthopedic surgery under general anesthesia were randomly allocated into 3 groups. Patients in groups A, B, and C received intravenous lidocaine, ketamine, or normal saline, respectively, during the operation. Then, postoperative pain scores, analgesic requirements, patient satisfaction, and patient sleepiness were recorded and compared among the 3 groups.

RESULTS

Numerical rating scales during the first hour postoperation were significantly lower in the lidocaine group than in the ketamine or control group (P < 0.001). The mean total amount of morphine consumption during the first 24-hour postoperation was 14.49 ± 26.89, 16.59 ± 30.65, and 21.72 ± 43.29 mg in the lidocaine, ketamine, and control group, respectively, being significantly lower in the lidocaine group in comparison with the other groups (P < 0.001). Patients in the lidocaine group were less restless, calmer, and less drowsy than patients in the ketamine and control group (P < 0.001).

DISCUSSION AND CONCLUSION

According to these findings, systemic lidocaine is more effective than systemic ketamine to improve the quality of acute pain management without causing any significant complications in patients with opioid use disorder.

Assessment of the Effect of Perioperative Venous Lidocaine on the Intensity of Pain and IL-6 Concentration After Laparoscopic Gastroplasty

BACKGROUND AND OBJECTIVES

Opioids are associated with sedation and respiratory depression. The primary objective of this study was to assess pain intensity after gastric bypass with lidocaine. The secondary objective was to assess the IL-6 concentration, consumption of morphine, time to morphine request, time to extubation, and side effects.

METHODS

Sixty patients aged 18 to 60 years, with ASA (American Society of Anesthesiologists) scores of 2 or 3, who underwent bariatric surgery were allocated to two groups. Patients in group 1 were administered lidocaine (1.5 mg/kg) 5 min before the induction of anesthesia, and group 2 was administered 0.9% saline solution in an equal volume. Subsequently, lidocaine (2 mg/kg/h) or 0.9% saline was infused during the entire surgical procedure. Anesthesia was performed with fentanyl (5 μg/kg), propofol, rocuronium, and sevoflurane. Postoperative patient-controlled analgesia was provided with morphine. The following were evaluated: pain intensity, IL-6, 24-h consumption of morphine, time to the morphine request, time to extubation, and adverse effects.

RESULTS

The lidocaine group had a lower pain intensity than the saline group for up to 1 h, with no differences between groups in IL-6 and time to extubation. The lidocaine group consumed less morphine within 24 h, had a longer time until the first supplemental morphine request, and had a lower incidence of nausea.

CONCLUSIONS

Lidocaine reduced the intensity of early postoperative pain, incidence of nausea, and consumption of morphine within 24 h and increased time to the first morphine request, without reducing the plasma concentrations of IL-6.

The effect of intraoperative lidocaine infusion on opioid consumption and pain after totally extraperitoneal laparoscopic inguinal hernioplasty: a randomized controlled trial

BACKGROUND

As a component of multimodal analgesia, the administration of systemic lidocaine is a well-known technique. We aimed to evaluate the efficacy of lidocaine infusion on postoperative pain-related outcomes in patients undergoing totally extraperitoneal (TEP) laparoscopies inguinal hernioplasty.

METHODS

In this randomized controlled double-blind study, we recruited 64 patients to receive either lidocaine 2% (intravenous bolus 1.5 mg. kg ^- 1 followed by an infusion of 2 mg. kg^- 1. h^- 1), or an equal volume of normal saline. The infusion was initiated just before the induction of anesthesia and discontinued after tracheal extubation. The primary outcome of the study was postoperative morphine equivalent consumption up to 24 h after surgery. Secondary outcomes included postoperative pain scores, nausea/vomiting (PONV), sedation, quality of recovery (scores based on QoR-40 questionnaire), patient satisfaction, and the incidence of chronic pain.

RESULTS

The median (IQR) cumulative postoperative morphine equivalent consumption in the first 24 h was 0 (0-1) mg in the lidocaine group and 4 [1-8] mg in the saline group (p < 0.001). Postoperative pain intensity at rest and during movement at various time points in the first 24 h were significantly lower in the lidocaine group compared with the saline group (p < 0.05). Fewer patients reported PONV in the lidocaine group than in the saline group (p < 0.05). Median QoR scores at 24 h after surgery were significantly better in the lidocaine group (194 (194-196) than saline group 184 (183-186) (p < 0.001). Patients receiving lidocaine were more satisfied with postoperative analgesia than those receiving saline (p = 0.02). No difference was detected in terms of postoperative sedation and chronic pain after surgery.

CONCLUSIONS

Intraoperative lidocaine infusion for laparoscopic TEP inguinal hernioplasty reduces opioid consumption, pain intensity, PONV and improves the quality of recovery and patient satisfaction.

TRIAL REGISTRATION

ClinicalTrials.gov- NCT02601651. Date of registration: November 10, 2015.

The Analgesic and Emotional Response to Intravenous Lidocaine Infusion in the Treatment of Postherpetic Neuralgia: A Randomized, Double-Blinded, Placebo-controlled Study

OBJECTIVES

This study evaluated the analgesic efficacy and emotional response to intravenous lidocaine infusion compared with placebo in patients with postherpetic neuralgia (PHN).

METHODS

In this randomized, double-blinded study, patients with PHN received 5 mg/kg intravenous lidocaine infusion or placebo. The primary outcome was pain measured by Visual Analogue Scale, Von Frey, and area of allodynia. Moreover, emotional status of anxiety and depression were evaluated by Self-rating Anxiety Scale (SAS) and Self-rating Depression Scale (SDS). Quality of life was assessed by Short Form Health Survey 36.

RESULTS

In total, 197 patients were enrolled and eligible data were collected from 183 of those patients. The Visual Analogue Scale scores were reduced to a minimum at 2 weeks (2.74, 2.99) after infusion, but no significant difference was found between the lidocaine and placebo groups. Similar changes were also found in mechanical pain threshold and area of allodynia. However, the lidocaine group was associated with a statistically significant reduction in consumption of analgesics with a relative risk of 6.2 (95% confidence interval [CI], 2.24-17.16). Lidocaine infusion also significantly improved the anxiety and depression status; the values of mean change in anxiety and depression were 3.89 (95% CI, 1.43-6.35) and 4.3 (95% CI, 0.63-7.98), respectively, at 2 weeks. Moreover, improvement was exhibited in Short Form Health Survey 36 health status, with the mean change of 49.81 (95% CI, 28.17-71.46) at 1 week, in particular scores on vitality, physical and emotional role functioning, and mental health.

CONCLUSIONS

The analgesic response of 5 mg/kg lidocaine intravenous infusion is comparable to placebo in patients with PHN, but intravenous lidocaine infusion significantly reduced total analgesic consumption, and improved the overall emotional and health status.

Continuous intravenous perioperative lidocaine infusion for postoperative pain and recovery in adults

BACKGROUND

The management of postoperative pain and recovery is still unsatisfactory in a number of cases in clinical practice. Opioids used for postoperative analgesia are frequently associated with adverse effects, including nausea and constipation, preventing smooth postoperative recovery. Not all patients are suitable for, and benefit from, epidural analgesia that is used to improve postoperative recovery. The non-opioid, lidocaine, was investigated in several studies for its use in multimodal management strategies to reduce postoperative pain and enhance recovery. This review was published in 2015 and updated in January 2017.

OBJECTIVES

To assess the effects (benefits and risks) of perioperative intravenous (IV) lidocaine infusion compared to placebo/no treatment or compared to epidural analgesia on postoperative pain and recovery in adults undergoing various surgical procedures.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and reference lists of articles in January 2017. We searched one trial registry contacted researchers in the field, and handsearched journals and congress proceedings. We updated this search in February 2018, but have not yet incorporated these results into the review.

SELECTION CRITERIA

We included randomized controlled trials comparing the effect of continuous perioperative IV lidocaine infusion either with placebo, or no treatment, or with thoracic epidural analgesia (TEA) in adults undergoing elective or urgent surgery under general anaesthesia. The IV lidocaine infusion must have been started intraoperatively, prior to incision, and continued at least until the end of surgery.

DATA COLLECTION AND ANALYSIS

We used Cochrane's standard methodological procedures. Our primary outcomes were: pain score at rest; gastrointestinal recovery and adverse events. Secondary outcomes included: postoperative nausea and postoperative opioid consumption. We used GRADE to assess the quality of evidence for each outcome.

MAIN RESULTS

We included 23 new trials in the update. In total, the review included 68 trials (4525 randomized participants). Two trials compared IV lidocaine with TEA. In all remaining trials, placebo or no treatment was used as a comparator. Trials involved participants undergoing open abdominal (22), laparoscopic abdominal (20), or various other surgical procedures (26). The application scheme of systemic lidocaine strongly varies between the studies related to both dose (1 mg/kg/h to 5 mg/kg/h) and termination of the infusion (from the end of surgery until several days after).The risk of bias was low with respect to selection bias (random sequence generation), performance bias, attrition bias, and detection bias in more than 50% of the included studies. For allocation concealment and selective reporting, the quality assessment yielded low risk of bias for only approximately 20% of the included studies.IV Lidocaine compared to placebo or no treatment We are uncertain whether IV lidocaine improves postoperative pain compared to placebo or no treatment at early time points (1 to 4 hours) (standardized mean difference (SMD) -0.50, 95% confidence interval (CI) -0.72 to -0.28; 29 studies, 1656 participants; very low-quality evidence) after surgery. Due to variation in the standard deviation (SD) in the studies, this would equate to an average pain reduction of between 0.37 cm and 2.48 cm on a 0 to 10 cm visual analogue scale . Assuming approximately 1 cm on a 0 to 10 cm pain scale is clinically meaningful, we ruled out a clinically relevant reduction in pain with lidocaine at intermediate (24 hours) (SMD -0.14, 95% CI -0.25 to -0.04; 33 studies, 1847 participants; moderate-quality evidence), and at late time points (48 hours) (SMD -0.11, 95% CI -0.25 to 0.04; 24 studies, 1404 participants; moderate-quality evidence). Due to variation in the SD in the studies, this would equate to an average pain reduction of between 0.10 cm to 0.48 cm at 24 hours and 0.08 cm to 0.42 cm at 48 hours. In contrast to the original review in 2015, we did not find any significant subgroup differences for different surgical procedures.We are uncertain whether lidocaine reduces the risk of ileus (risk ratio (RR) 0.37, 95% CI 0.15 to 0.87; 4 studies, 273 participants), time to first defaecation/bowel movement (mean difference (MD) -7.92 hours, 95% CI -12.71 to -3.13; 12 studies, 684 participants), risk of postoperative nausea (overall, i.e. 0 up to 72 hours) (RR 0.78, 95% CI 0.67 to 0.91; 35 studies, 1903 participants), and opioid consumption (overall) (MD -4.52 mg morphine equivalents , 95% CI -6.25 to -2.79; 40 studies, 2201 participants); quality of evidence was very low for all these outcomes.The effect of IV lidocaine on adverse effects compared to placebo treatment is uncertain, as only a small number of studies systematically analysed the occurrence of adverse effects (very low-quality evidence).IV Lidocaine compared to TEAThe effects of IV lidocaine compared with TEA are unclear (pain at 24 hours (MD 1.51, 95% CI -0.29 to 3.32; 2 studies, 102 participants), pain at 48 hours (MD 0.98, 95% CI -1.19 to 3.16; 2 studies, 102 participants), time to first bowel movement (MD -1.66, 95% CI -10.88 to 7.56; 2 studies, 102 participants); all very low-quality evidence). The risk for ileus and for postoperative nausea (overall) is also unclear, as only one small trial assessed these outcomes (very low-quality evidence). No trial assessed the outcomes, 'pain at early time points' and 'opioid consumption (overall)'. The effect of IV lidocaine on adverse effects compared to TEA is uncertain (very low-quality evidence).

AUTHORS' CONCLUSIONS

We are uncertain whether IV perioperative lidocaine, when compared to placebo or no treatment, has a beneficial impact on pain scores in the early postoperative phase, and on gastrointestinal recovery, postoperative nausea, and opioid consumption. The quality of evidence was limited due to inconsistency, imprecision, and study quality. Lidocaine probably has no clinically relevant effect on pain scores later than 24 hours. Few studies have systematically assessed the incidence of adverse effects. There is a lack of evidence about the effects of IV lidocaine compared with epidural anaesthesia in terms of the optimal dose and timing (including the duration) of the administration. We identified three ongoing studies, and 18 studies are awaiting classification; the results of the review may change when these studies are published and included in the review.

Effect of intravenous lidocaine infusion on long-term postoperative pain after spinal fusion surgery

BACKGROUND

Intravenous lidocaine infusion is known to reduce postoperative pain for days or weeks beyond the infusion time, and plasma half-life in several types of surgical procedures.

OBJECTIVES

To evaluate the effect of intravenous (IV) lidocaine infusion on long term postoperative pain intensity for 3 months in patients undergoing spinal fusion surgery.

STUDY DESIGN

Prospective randomized, double-blinded study.

SETTING

Assiut University Hospital, Assiut, Egypt.

METHODS

Forty patients undergoing spinal fusion surgery were randomized into 2 equal groups (n = 20 in each). Patients in the lidocaine group received IV lidocaine at a dosage of 2.0 mg/kg slowly before induction of anesthesia, followed by lidocaine IV infusion at a rate of 3.0 mg/kg/h until the end of surgery. Patients in the control group received an equal volume of normal saline. The following data were assessed: pain by Visual Analog Score (VAS) at 1 hour, 6 hours, 12 hours, 24 hours, 48 hours, at discharge time, and at 1 month, 2 months, and 3 months post-operation, time to first request for additional analgesia, and total morphine consumption in 24 hours.

RESULTS

Lidocaine significantly reduced the postoperative pain score (VAS) for up to 3 months (P < .05), and significantly reduced morphine consumption (4.5 mg vs. 19.85 mg) in the 1st 24 hours postoperative. Lidocaine also significantly, prolonged (P < .05) the time to first request for additional analgesia (9.56 ± 2.06 hours vs 1.82 ± 0.91 hours).

CONCLUSION

Intra-operative lidocaine, when given intravenously as a bolus followed by an infusion, significantly decreased long term postoperative back pain intensity in patients undergoing spinal fusion surgery.

Intravenous lidocaine for effective pain relief after bimaxillary surgery

OBJECTIVES

The aim of this prospective, randomized, double-blind, placebo-controlled study was to evaluate the analgesic effect of intravenous lidocaine on postoperative pain in bimaxillary surgery.

MATERIALS AND METHODS

Between July 2015 and November 2015, 52 consecutive patients that underwent bimaxillary surgery were recruited to the present study. The patients were randomly divided into two groups: group L (1.5 mg/kg bolus and 2 mg/kg/h continuous infusion during the operation) and group C (normal saline). To measure pain intensity, a visual analog scale (VAS) was used at 2, 4, 8, 12, 24, and 48 h after surgery. Rescue ketorolac use was measured in the first 4, 4-8, 8-24, and 24-48 h after surgery. Total ketorolac consumption (the sum of rescue and eight-hourly fixed schedule ketorolac injection), WBC count, neutrophil count, and postoperative swelling were recorded.

RESULTS

There were no significant differences between the two groups with respect to demographics. VAS pain scores were significantly lower in group L compared with group C up to 8 h after surgery. Rescue ketorolac use up to 8 h after surgery and total ketorolac consumption were significantly lower in group L than in group C. Postoperative WBC and neutrophil counts were significantly decreased in group L. Compared with group C, the amount of calibrated postoperative swelling was lower in group L.

CONCLUSIONS

Systemic lidocaine infusion during bimaxillary surgery reduces postoperative pain, analgesic consumption, and facial swelling.

CLINICAL RELEVANCE

Systemic lidocaine is simple, economic, and a safe procedure reducing pain and soft tissue swelling after bimaxillary surgery.

Lidocaine Infusion: A Promising Therapeutic Approach for Chronic Pain

Opioid abuse is a national epidemic in the United States, where it is estimated that a prescription drug overdose death occurs every 19 minutes. While opioids are highly effective in acute and subacute pain control, their use for treatment of chronic pain is controversial. Chronic opioids use is associated with tolerance, dependency, hyperalgesia. Although there are new strategies and practice guidelines to reduce opioid dependence and opioid prescription drug overdose, there has been little focus on development of opioid-sparing therapeutic approaches. Lidocaine infusion has been shown to be successful in controlling pain where other agents have failed. The opioid sparing properties of lidocaine infusion added to its analgesic and antihyperalgesic properties make lidocaine infusion a viable option for pain control in opioid dependent patients. In this review, we provide an overview of the opioid abuse epidemic, and we outline current evidence supporting the potential use of lidocaine infusion as an adjuvant therapeutic approach for management of chronic pain.

Post-operative analgesic effect of dexmedetomidine administration in wound infiltration for abdominal hysterectomy: A randomised control study

Background and Aims:

Local infiltration of the surgical wound is one of the important components of multimodal analgesia for post-operative pain relief. This study determines the post-operative analgesic effect of addition of dexmedetomidine to bupivacaine for local infiltration of the surgical wound.

Methods:

Sixty women belonging to American Society of Anesthesiologists’ Grade 1 or 2 posted for abdominal hysterectomy were randomly allocated to Group I (control group) where patients received wound infiltration with 30 mL 0.25% bupivacaine at the end of surgery, or Group II, where patients received wound infiltration with 1.0 μg/kg dexmedetomidine diluted in 30 mL 0.25% bupivacaine. The primary objective of the study was to assess post-operative pain scores. Number of patients requiring rescue analgesia and total morphine consumption during 24 h after surgery were also recorded. Statistical significance for analgesic requirement was determined by one-way analysis of variance.

Results:

Pain scores were lower at rest for 12 h and on cough for 6 h in Group II (<0.01). All patients in Group I required supplemental morphine compared to only 3 patients in Group II (P < 0.003). Post-operative analgesia requirement was significantly less in patients receiving dexmedetomidine in wound infiltration compared to patients receiving bupivacaine alone (P < 0.001).

Conclusions:

Wound infiltration of dexmedetomidine with bupivacaine provides superior pain relief compared to bupivacaine alone.

Intravenous lidocaine for effective pain relief after a laparoscopic colectomy: a prospective, randomized, double-blind, placebo-controlled study

A perioperative intravenous lidocaine infusion has been reported to decrease postoperative pain. The goal of this study was to evaluate the effectiveness of intravenous lidocaine in reducing postoperative pain for laparoscopic colectomy patients. Fifty-five patients scheduled for an elective laparoscopic colectomy were randomly assigned to 2 groups. Group L received an intravenous bolus injection of lidocaine 1.5 mg/kg before intubation, followed by 2 mg/kg/h continuous infusion during the operation. Group C received the same dosage of saline at the same time. Postoperative pain was assessed at 2, 4, 8, 12, 24, and 48 hours after surgery by using the visual analog scale (VAS). Fentanyl consumption by patient-controlled plus investigator-controlled rescue administration and the total number of button pushes were measured at 2, 4, 8, 12, 24, and 48 hours after surgery. In addition, C-reactive protein (CRP) levels were checked on the operation day and postoperative days 1, 2, 3, and 5. VAS scores were significantly lower in group L than group C until 24 hours after surgery. Fentanyl consumption was lower in group L than group C until 12 hours after surgery. Moreover, additional fentanyl injections and the total number of button pushes appeared to be lower in group L than group C (P < 0.05). The CRP level tended to be lower in group L than group C, especially on postoperative day 1 and 2 and appeared to be statistically significant. The satisfaction score was higher in group L than group C (P = 0.024). Intravenous lidocaine infusion during an operation reduces pain after a laparoscopic colectomy.

Continuous intravenous perioperative lidocaine infusion for postoperative pain and recovery

BACKGROUND

The management of postoperative pain and recovery is still unsatisfactory in clinical practice. Opioids used for postoperative analgesia are frequently associated with adverse effects including nausea and constipation. These adverse effects prevent smooth postoperative recovery. On the other hand not all patients may be suited to, and take benefit from, epidural analgesia used to enhance postoperative recovery. The non-opioid lidocaine was investigated in several studies for its use in multi-modal management strategies to reduce postoperative pain and enhance recovery.

OBJECTIVES

The aim of this review was to assess the effects (benefits and risks) of perioperative intravenous lidocaine infusion compared to placebo/no treatment or compared to epidural analgesia on postoperative pain and recovery in adults undergoing various surgical procedures.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 5 2014), MEDLINE (January 1966 to May 2014), EMBASE (1980 to May 2014), CINAHL (1982 to May 2014), and reference lists of articles. We searched the trial registry database ClinicalTrials.gov, contacted researchers in the field, and handsearched journals and congress proceedings. We did not apply any language restrictions.

SELECTION CRITERIA

We included randomized controlled trials comparing the effect of continuous perioperative intravenous lidocaine infusion either with placebo, or no treatment, or with epidural analgesia in adults undergoing elective or urgent surgery under general anaesthesia. The intravenous lidocaine infusion must have been started intraoperatively prior to incision and continued at least until the end of surgery.

DATA COLLECTION AND ANALYSIS

Trial quality was independently assessed by two authors according to the methodological procedures specified by the Cochrane Collaboration. Data were extracted by two independent authors. We collected trial data on postoperative pain, recovery of gastrointestinal function, length of hospital stay, postoperative nausea and vomiting (PONV), opioid consumption, patient satisfaction, surgical complication rates, and adverse effects of the intervention.

MAIN RESULTS

We included 45 trials involving 2802 participants. Two trials compared intravenous lidocaine versus epidural analgesia. In all the remaining trials placebo or no treatment was used as a comparator. Trials involved participants undergoing open abdominal (12), laparoscopic abdominal (13), or various other surgical procedures (20).The risk of bias was low with respect to selection bias (random sequence generation), performance bias, attrition bias, and detection bias in more than 50% of the included studies. For allocation concealment and selective reporting the quality assessment yielded low risk of bias for only approximately 20% of the included studies.We found evidence of effect for intravenous lidocaine on the reduction of postoperative pain (visual analogue scale, 0 to 10 cm) compared to placebo or no treatment at 'early time points (one to four hours)' (mean difference (MD) -0.84 cm, 95% confidence interval (CI) -1.10 to -0.59; low-quality evidence) and at 'intermediate time points (24 hours)' (MD -0.34 cm, 95% CI -0.57 to -0.11; low-quality evidence) after surgery. However, no evidence of effect was found for lidocaine to reduce pain at 'late time points (48 hours)' (MD -0.22 cm, 95% CI -0.47 to 0.03; low-quality evidence). Pain reduction was most obvious at 'early time points' in participants undergoing laparoscopic abdominal surgery (MD -1.14, 95% CI -1.51 to -0.78; low-quality evidence) and open abdominal surgery (MD -0.72, 95% CI -0.96 to -0.47; moderate-quality evidence). No evidence of effect was found for lidocaine to reduce pain in participants undergoing all other surgeries (MD -0.30, 95% CI -0.89 to 0.28; low-quality evidence). Quality of evidence is limited due to inconsistency and indirectness (small trial sizes).Evidence of effect was found for lidocaine on gastrointestinal recovery regarding the reduction of the time to first flatus (MD -5.49 hours, 95% CI -7.97 to -3.00; low-quality evidence), time to first bowel movement (MD -6.12 hours, 95% CI -7.36 to -4.89; low-quality evidence), and the risk of paralytic ileus (risk ratio (RR) 0.38, 95% CI 0.15 to 0.99; low-quality evidence). However, no evidence of effect was found for lidocaine on shortening the time to first defaecation (MD -9.52 hours, 95% CI -23.24 to 4.19; very low-quality evidence).Furthermore, we found evidence of positive effects for lidocaine administration on secondary outcomes such as reduction of length of hospital stay, postoperative nausea, intraoperative and postoperative opioid requirements. There was limited data on the effect of IV lidocaine on adverse effects (e.g. death, arrhythmias, other heart rate disorders or signs of lidocaine toxicity) compared to placebo treatment as only a limited number of studies systematically analysed the occurrence of adverse effects of the lidocaine intervention.The comparison of intravenous lidocaine versus epidural analgesia revealed no evidence of effect for lidocaine on relevant outcomes. However, the results have to be considered with caution due to imprecision of the effect estimates.

AUTHORS' CONCLUSIONS

There is low to moderate evidence that this intervention, when compared to placebo, has an impact on pain scores, especially in the early postoperative phase, and on postoperative nausea. There is limited evidence that this has further impact on other relevant clinical outcomes, such as gastrointestinal recovery, length of hospital stay, and opioid requirements. So far there is a scarcity of studies that have systematically assessed the incidence of adverse effects; the optimal dose; timing (including the duration of the administration); and the effects when compared with epidural anaesthesia.

THE EFFECT OF OBESITY ON DOSE OF DEXMEDETOMIDINE WHEN ADMINISTERED WITH FENTANYL DURING POSTOPERATIVE MECHANICAL VENTILATION--RETROSPECTIVE

We carried out a retrospective investigation on the effect of obesity on dexmedetomidine (DEX) requirements when administered with fentanyl (FEN) during mechanical ventilation after major surgeries. After Institutional Review Board approval, 14 obese patients with a body mass index (BMI) ≥ 30 kg/m(2) and the same number of non-obese patients with similar backgrounds to the obese patients were selected from medical records. Doses of DEX in the first 48 h or until the end of sedation or extubation were calculated for comparison. In addition to comparison of dosing between the groups, associations between total body weight (TBW), BMI, and lean body mass (LBM) values and doses of DEX (mcg/h), between BMI and various indices (i.e., amount per TBW per hour and amount per LBM per hour) of DEX doses, and between above indices of DEX and FEN doses were also examined. There were no significant differences in DEX dose indices between the groups. However, DEX requirements (mcg/h) were significantly increased with TBW (kg) (r = 0.51, P = 0.003), BMI (r = 0.49, P = 0.006) and LBM (kg) (r = 0.42, P = 0.02), which might have enhanced the DEX metabolism with physiological changes with obesity. These findings will be beneficial for future clinical pharmacological analysis of DEX.

[Effect of intraoperative intravenous lidocaine on pain and plasma interleukin-6 in patients undergoing hysterectomy]

BACKGROUND AND OBJECTIVES

Interleukin-6 (IL-6) is a predictor of trauma severity. The purpose of this study was to evaluate the effect of intravenous lidocaine on pain severity and plasma IL-6 after hysterectomy.

METHOD

A prospective, randomized, comparative, double-blind study with 40 patients, aged 18-60 years. G1 received lidocaine (2mg.kg(-1).h(-1)) or G2 received 0.9% saline solution during the operation. Anesthesia was induced with O2/isoflurane. Pain severity (T0: awake and 6, 12, 18 and 24hours), first analgesic request, and dose of morphine in 24hours were evaluated. IL-6 was measured before starting surgery (T0), five hours after the start (T5), and 24hours after the end of surgery (T24).

RESULTS

There was no difference in pain severity between groups. There was a decrease in pain severity between T0 and other measurement times in G1. Time to first supplementation was greater in G2 (76.0±104.4min) than in G1 (26.7±23.3min). There was no difference in supplemental dose of morphine between G1 (23.5±12.6mg) and G2 (18.7±11.3mg). There were increased concentrations of IL-6 in both groups from T0 to T5 and T24. There was no difference in IL-6 dosage between groups. Lidocaine concentration was 856.5±364.1 ng.mL(-1) in T5 and 30.1±14.2 ng.mL(-1) in T24.

CONCLUSION

Intravenous lidocaine (2mg.kg(-1).h(-1)) did not reduce pain severity and plasma levels of IL-6 in patients undergoing abdominal hysterectomy.

Intraoperative systemic lidocaine for pre-emptive analgesics in subtotal gastrectomy: a prospective, randomized, double-blind, placebo-controlled study

BACKGROUND

Pre-emptive intravenous lidocaine infusion is known to improve postoperative pain in abdominal surgery. We assessed the effect of intravenous lidocaine infusion in patients who underwent subtotal gastrectomy.

METHODS

We conducted a double-blind, placebo-controlled study with patients undergoing subtotal gastrectomy for early gastric cancer divided into 2 groups: 1 group received intravenous lidocaine infusion preoperatively and throughout surgery, and the other received normal saline infusion (placebo). We assessed postoperative outcomes, including pain scores on a visual analogue scale (VAS), administration frequency of patient-controlled analgesia (PCA) and the amount of consumed fentanyl. Postoperative nausea and vomiting, length of hospital stay (LOS), time to return to regular diet and patient satisfaction at discharge were evaluated.

RESULTS

There were 36 patients in our study. Demographic characteristics were similar between the groups. The VAS pain scores and administration frequency of PCA were significantly lower in the lidocaine group until 24 hours after surgery, and fentanyl consumption was significantly lower in this group until 12 hours postoperatively compared with the placebo group. The total amount of consumed fentanyl and the total administration frequency of PCA were significantly lower in the lidocaine than the control group. No significant differences were detected in terms of nausea and vomiting, return to regular diet, LOS and patient satisfaction, and there were no reported side-effects of lidocaine.

CONCLUSION

Intravenous lidocaine infusion reduces pain during the postoperative period after subtotal gastrectomy.

Preventive analgesia by local anesthetics: the reduction of postoperative pain by peripheral nerve blocks and intravenous drugs

The use of local anesthetics to reduce acute postoperative pain has a long history, but recent reports have not been systematically reviewed. In addition, the need to include only those clinical studies that meet minimum standards for randomization and blinding must be adhered to. In this review, we have applied stringent clinical study design standards to identify publications on the use of perioperative local anesthetics. We first examined several types of peripheral nerve blocks, covering a variety of surgical procedures, and second, we examined the effects of intentionally administered IV local anesthetic (lidocaine) for suppression of postoperative pain. Thirdly, we have examined publications in which vascular concentrations of local anesthetics were measured at different times after peripheral nerve block procedures, noting the incidence when those levels reached ones achieved during intentional IV administration. Importantly, the very large number of studies using neuraxial blockade techniques (epidural, spinal) has not been included in this review but will be dealt with separately in a later review. The overall results showed a strongly positive effect of local anesthetics, by either route, for suppressing postoperative pain scores and analgesic (opiate) consumption. In only a few situations were the effects equivocal. Enhanced effectiveness with the addition of adjuvants was not uniformly apparent. The differential benefits between drug delivery before, during, or immediately after a surgical procedure are not obvious, and a general conclusion is that the significant antihyperalgesic effects occur when the local anesthetic is present during the acute postoperative period, and its presence during surgery is not essential for this action.