Low-dose lidocaine suppresses experimentally induced hyperalgesia in humans

Serum lidocaine (lignocaine) concentrations during prolonged perioperative infusion in patients undergoing breast cancer surgery: A secondary analysis of a randomised controlled trial

Perioperative lidocaine (lignocaine) infusions are being employed with increasing frequency. The determinants of systemic lidocaine concentrations during prolonged administration are unclear. In the Long-term Outcomes after Lidocaine Infusions for PostOperative Pain (LOLIPOP) pilot trial, the impact of infusion duration and body size metrics on serum lidocaine concentrations was examined with regression models in 48 women undergoing breast cancer surgery. Lidocaine was delivered as an intravenous bolus (1.5 mg/kg) and infusion (2 mg/kg per h) intraoperatively, followed by a 12-h subcutaneous infusion (1.33 mg/kg per h) postoperatively. Dosing was based on total body weight. Wound infiltration with other long-acting local anaesthetics was permitted. Protein binding and pharmacogenomic data were also collected. Lidocaine concentrations (median (interquartile range) (range)) during prolonged administration were in the safe and potentially therapeutic range: post-anaesthesia care unit 2.16 (1.73-2.82) (1.12-6.06) µg/ml; ward 1.41 (1.22-1.75) (0.64-2.81) µg/ml. Concentrations increased non-linearly during the early intravenous phase of administration (mean rise 1.21 µg/ml per hour of infusion, P = 0.007) but reached a pseudo steady-state during the later subcutaneous phase. Higher dose rates received per kilogram of lean (P = 0.004), adjusted (P = 0.006) and ideal body weight (P = 0.009) were associated with higher steady-state concentrations. The lidocaine free fraction was unaffected by the presence of ropivacaine, and phenotypes linked to slow metabolism were infrequent. Serum lidocaine concentrations reached a pseudo steady-state during a 12-h postoperative infusion. Greater precision in steady-state concentrations can be achieved by dosing on lean body weight versus adjusted or ideal body weight (equivalent lean body weight doses: intravenous bolus 2.5 mg/kg; intravenous infusion 3.33 mg/kg per h; subcutaneous infusion 2.22 mg/kg per h.

Perioperative intravenous lidocaine for postoperative pain in patients undergoing breast surgery: a meta-analysis with trial sequential analysis of randomized controlled trials

Background

The effectiveness of intravenous lidocaine infusion in managing acute and chronic pain following breast surgery has been a topic of debate. This meta-analysis aims to assess the impact of perioperative intravenous lidocaine on the relief of postoperative pain among patients undergoing breast surgery.

Methods

A systematic search of databases was conducted to identify randomized controlled trials (RCTs) that compared the effects of intravenous lidocaine infusion with placebo or routine care in patients undergoing breast surgery. The primary outcome of interest was the occurrence of chronic post-surgical pain (CPSP) at the longest follow-up. Meta-analyses, incorporating trial sequential analysis, were performed using a random-effects model to assess the overall effect.

Results

A total of twelve trials, involving 879 patients, were included in the analysis. Perioperative intravenous lidocaine demonstrated a significant reduction in the incidence of CPSP at the longest follow-up (risk ratio [RR] 0.62, 95% confidence interval [CI] 0.48-0.81; P = 0.0005; I2 = 6%). Trial sequential analysis (TSA) indicated that the cumulative z curve crossed the trial sequential monitoring boundary for benefit, providing sufficient and conclusive evidence. Furthermore, intravenous lidocaine was associated with decreased opioid consumption and a shorter length of hospital stay.

Conclusion

Perioperative intravenous lidocaine is effective in relieving acute and CPSP in patients undergoing breast surgery.

Systematic review registration

https://inplasy.com/, identifier INPLASY2022100033.

Clinical Efficacy of Perioperative Intravenous Dexmedetomidine and Lidocaine Combined Infusion for Thyroidectomy: A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial

OBJECTIVES

The aim of this study was to evaluate the efficacy of perioperative dexmedetomidine (DEX) combined with lidocaine intravenous infusion on relieving postoperative pain and improving recovery for patients undergoing thyroidectomy.

MATERIALS AND METHODS

A total of 138 patients undergoing thyroidectomy with general anesthesia were randomly divided into 4 groups: lidocaine (1.5 mg/kg bolus followed by 2 mg/kg/h infusion) in the group L, DEX (0.5 µg/kg) in the group D, lidocaine (same as the group L) with DEX (0.5 µg/kg) in the group L+D, and placebo as normal saline in the group C. All drugs were infused until the end of the surgery. The visual analog scale (VAS) scores of patients at 1, 4, 8, 12, and 24 hours following surgery, opioid requirement, propofol consumption, incidence of postoperative nausea and vomiting, awaking time, hemodynamic variables, and any adverse effects were assessed.

RESULTS

Compared with the group C, the VAS scores in the group L+D were significantly lower until 8 hours after surgery (P<0.05), while the VAS scores were significantly decreased just until 4 hours in the group L and 1 hour in the group D after surgery (P<0.05). There was no significant difference in opioid consumption between 4 groups. Propofol consumption in the group L+D was significantly lower than other groups (P<0.05). Compared with the group C, the incidence of postoperative nausea and vomiting in the group L+D was lower (P<0.05), and awaking time in the group L+D and the group L was shorter (P<0.05).

CONCLUSION

DEX combined with lidocaine infusion can effectively attenuate the postoperative pain without any serious adverse events, which may improve postoperative recovery in patients undergoing thyroidectomy.

Utilization of Intravenous Lidocaine Infusion for the Treatment of Refractory Chronic Pain

Context

Chronic pain accounts for one of the most common reasons patients seek medical care. The financial burden of chronic pain on health care is seen by direct financial cost and resource utilization. Many risk factors may contribute to chronic pain, but there is no definite risk. Managing chronic pain is a balance between maximally alleviating symptoms by utilizing a therapeutic regimen that is safe for long-term use. Currently, non-opioid analgesics, NSAIDs, and opioids are some of the medical treatment options, but these have numerous adverse effects and may not be the best option for long-term use. However, Lidocaine can achieve both central and peripheral analgesic effects with relatively few side effects, which may be an ideal compound for managing chronic pain.

Evidence Acquisition

This is a Narrative Review.

Results

Infusion of lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide), an amino-amide compound, is emerging as a promising option to fill the therapeutic void for treatment of chronic pain. Numerous studies have outlined dosing protocols for lidocaine infusion for the management of perioperative pain, outlined below. While there are slight variations in these different protocols, they all center around a similar dosing regimen to administer a bolus to reach a rapid steady state, followed by infusion for up to 72 hours to maintain the therapeutic analgesic effects.

Conclusions

Lidocaine may be a promising pharmacologic solution with a low side effect profile that provides central and peripheral analgesia. Even though the multifaceted mechanism is not entirely understood yet, lidocaine may be a promising novel remedy in treating chronic pain in various conditions.

The analgesic effect of intravenous lidocaine versus intrawound or epidural bupivacaine for postoperative opioid reduction in spine surgery: A systematic review and meta-analysis

BACKGROUND

Pain management following spine surgery remains a challenge. The significant use of opioids may lead to opioid-related adverse events. These complications can increase perioperative morbidity and rapidly expend health care resources by developing chronic pain. Although intraoperative pain control for surgery has been studied in the literature, a thorough assessment of the effect in spine surgery is rarely reported. The objective of the present study was to examine the outcomes of intraoperative intravenous lidocaine and intrawound or epidural bupivacaine use in spine surgery.

METHODS

An electronic literature search was conducted for studies on the use of lidocaine and bupivacaine in spine surgery for all years available. Only articles in English language were included. Postoperative opioid consumption, VAS score, nausea/vomiting, and length of hospital stay comprised the outcomes of interest. Pooled descriptive statistics with Risk Ratios (RR), Mean Differences (MD) and 95 % confidence interval were used to synthesize the outcomes for each medication.

RESULTS

A total of 10 studies (n = 579) were included in the analysis. Comparison of the opioid consumption revealed a significant mean difference between lidocaine and bupivacaine (MD: -12.25, and MD: -0.4, respectively, p = 0.01), favoring lidocaine. With regard to postoperative VAS, the pooled effect of both groups decreased postoperative pain (MD: -0.61 (95 % CI: -1.14, -0.08)), with a more significant effect in the lidocaine group (MD: -0.84, (95 % CI: -1.21, -0.48)). There was no significant effect in length of stay, and postoperative nausea/vomiting.

CONCLUSIONS

The results of the present meta-analysis indicate that lidocaine and bupivacaine use may decrease postoperative pain and opioid consumption. Lidocaine had a stronger effect on the reduction of opioid consumption compared to bupivacaine.

Nerve growth factor sensitizes nociceptors to C-fibre selective supra-threshold electrical stimuli in human skin

BACKGROUND

Intradermal injection of 1 µg nerve growth factor (NGF) causes sustained nociceptor sensitization. Slowly depolarizing electrical current preferentially activates C-nociceptors.

METHODS

We explored the differential contribution of A-delta and C-nociceptors in NGF-sensitized skin using slowly depolarizing transcutaneous electrical current stimuli, CO2 laser heat, mechanical impact, and A-fibre compression block. In 14 healthy volunteers, pain rating was recorded on a numeric scale at days 1-14 after NGF treatment. Ratings during A-fibre conduction block were investigated at days 3 and 7 post-NGF.

RESULTS

Pain ratings to electrical, CO2 heat and mechanical impact stimuli were enhanced (>30%, p < .0005, ANOVA) at NGF-injection sites. Axon reflex erythema evoked by electrical stimulation was also larger at NGF-injection sites (p < .02, ANOVA). Diminution of pain during continuous (1 min) sinusoidal current stimulation at 4 Hz was less pronounced after NGF (p < .05, ANOVA). Pain ratings to electrical sinusoidal and mechanical impact stimuli during A-fibre conduction block were significantly elevated at the NGF sites compared to NaCl-treated skin (p < .05, ANOVA).

CONCLUSIONS

NGF-induced sensitization of human skin to electrical and mechanical stimuli is primarily driven by C-nociceptors with little contribution from A-delta fibres. Less-pronounced accommodation during ongoing sinusoidal stimulation suggests that NGF could facilitate axonal spike generation and conduction in primary afferent nociceptors in humans. Further studies using this sinusoidal electrical stimulation profile to investigate patients with chronic inflammatory pain may allow localized assessment of skin C-nociceptors and their putative excitability changes under pathologic conditions.

SIGNIFICANCE

The application of novel slowly depolarizing electrical stimuli demonstrated a predominant C-nociceptor sensitization in NGF-treated skin. Increased pain ratings, larger axon reflex erythema and less accommodation of C-fibres to ongoing sinusoidal stimulation all indicated an enhanced nociceptor discharge after NGF. A-fibre conduction block had little effect on electrical and mechanical hyperalgesia skin in NGF-treated compared to NaCl-treated skin. This electrical stimulus profile may be applicable for patients with chronic inflammatory pain, allowing localized assessment of skin C-nociceptors and their putative excitability changes under pathologic conditions.

The use of intravenous lidocaine for postoperative pain and recovery: international consensus statement on efficacy and safety

Intravenous lidocaine is used widely for its effect on postoperative pain and recovery but it can be, and has been, fatal when used inappropriately and incorrectly. The risk-benefit ratio of i.v. lidocaine varies with type of surgery and with patient factors such as comorbidity (including pre-existing chronic pain). This consensus statement aims to address three questions. First, does i.v. lidocaine effectively reduce postoperative pain and facilitate recovery? Second, is i.v. lidocaine safe? Third, does the fact that i.v. lidocaine is not licensed for this indication affect its use? We suggest that i.v. lidocaine should be regarded as a 'high-risk' medicine. Individual anaesthetists may feel that, in selected patients, i.v. lidocaine may be beneficial as part of a multimodal peri-operative pain management strategy. This approach should be approved by hospital medication governance systems, and the individual clinical decision should be made with properly informed consent from the patient concerned. If i.v. lidocaine is used, we recommend an initial dose of no more than 1.5 mg.kg^-1 , calculated using the patient's ideal body weight and given as an infusion over 10 min. Thereafter, an infusion of no more than 1.5 mg.kg^-1 .h^-1 for no longer than 24 h is recommended, subject to review and re-assessment. Intravenous lidocaine should not be used at the same time as, or within the period of action of, other local anaesthetic interventions. This includes not starting i.v. lidocaine within 4 h after any nerve block, and not performing any nerve block until 4 h after discontinuing an i.v. lidocaine infusion.

The effect of preoperative intravenous lidocaine on postoperative pain following hysteroscopy: A randomized controlled trial

BACKGROUND

The use of hysteroscopy for the diagnosis and treatment of uterine and endometrial abnormalities is often associated with postoperative pain. This randomized controlled trial aimed to assess the efficacy of preoperative intravenous (IV) lidocaine in reducing pain after hysteroscopy.

METHODS

In total, 138 patients undergoing elective hysteroscopy at the CHA Bundang Medical Center, Seongnam, Korea were randomly assigned to a control group (n = 69) or a lidocaine group (n = 69), which received normal saline or IV lidocaine at 1.5 mg/kg, respectively. The primary outcome was the incidence of postoperative pain.

RESULTS

The incidence of pain was significantly lower in the IV lidocaine group than in the control group at the post-anesthesia care unit (27.3% vs 68.2%, P < .001). The visual analog scale (0-10) score (median [interquartile range]) was lower in the IV lidocaine group than in the control group (0 [0-2]) vs 2 [0-4]), P < .001). The use of rescue analgesics and postoperative nausea and vomiting were similar between the 2 groups. This study demonstrated that administering 1.5 mg/kg of preoperative IV lidocaine can be a simple method to reduce incidence of pain after hysteroscopy.

CONCLUSION

Preoperative bolus administration of 1.5 mg/kg of IV lidocaine may be used to decrease incidence of pain after hysteroscopy under general anesthesia.

Intraoperative lidocaine infusion and 24-hour postoperative opioid consumption in obese patients undergoing laparoscopic bariatric surgery

BACKGROUND

Bariatric surgery is the most effective long-term treatment for obesity. Opioid-sparing anesthesia and multimodal analgesia such as lidocaine infusion have been recommended in these patients to reduce opioid-related complications. However, evidence supporting its use for bariatric surgery population is limited.

OBJECTIVE

To investigate whether intraoperative lidocaine infusion is associated with decreasing opioid consumption in laparoscopic bariatric surgery.

SETTING

A university hospital, California, USA.

METHODS

In this retrospective cohort study, outcomes among consecutive obese patients undergoing laparoscopic bariatric surgery between January 2016 to December 2018 were evaluated to determine the impact of adjunctive intraoperative lidocaine infusion on 24-hour postoperative opioid consumption. Secondary outcomes, including opioid consumption during hospitalization, length of stay, and postoperative complications were determined. Post hoc analyses were performed exploring possible dose effects and drug-drug interactions. Univariable and multivariable analyses were performed to identify factors associated with opioid consumption.

RESULTS

Among 345 patients, 54 (15.7%) received intraoperative lidocaine infusion (L+) whereas 291 (84.3%) did not receive intraoperative lidocaine infusion (L-). Both L+ and L- groups shared similar demographic characteristics. The 24-hour postoperative opioid consumption was 17.6% lower in L+ (95% confidence interval -28.4 to -5.2, P = .007), but nonsignificantly lower in the multivariate model (12.8%, 95% confidence interval -24.4 to .5, P = .06). Opioid consumption during hospitalization, length of stay, and other clinically significant outcomes did not differ. However, subgroup analysis restricted to opioid-naïve patients indicated significantly reduced opioid consumption in the L+ group. Post hoc analysis suggested interaction between lidocaine and ketamine in decreasing 24-hour postoperative opioid consumption.

CONCLUSIONS

Intraoperative lidocaine infusion was not significantly associated with decreasing 24-hour postoperative opioid consumption in obese patients undergoing laparoscopic bariatric surgery.

Cutaneous TRPV1+ Neurons Trigger Protective Innate Type 17 Anticipatory Immunity

Cutaneous TRPV1⁺ neurons directly sense noxious stimuli, inflammatory cytokines, and pathogen-associated molecules and are required for innate immunity against some skin pathogens. Important unanswered questions are whether TRPV1⁺ neuron activation in isolation is sufficient to initiate innate immune responses and what is the biological function for TRPV1⁺ neuron-initiated immune responses. We used TRPV1-Ai32 optogenetic mice and cutaneous light stimulation to activate cutaneous neurons in the absence of tissue damage or pathogen-associated products. We found that TRPV1⁺ neuron activation was sufficient to elicit a local type 17 immune response that augmented host defense to C. albicans and S. aureus. Moreover, local neuron activation elicited type 17 responses and augmented host defense at adjacent, unstimulated skin through a nerve reflex arc. These data show the sufficiency of TRPV1⁺ neuron activation for host defense and demonstrate the existence of functional anticipatory innate immunity at sites adjacent to infection that depends on antidromic neuron activation.

Ropivacaine preperitoneal wound infusion for pain relief and prevention of incisional hyperalgesia after laparoscopic colorectal surgery: a randomized, triple-arm, double-blind controlled evaluation vs intravenous lidocaine infusion, the CATCH study

AIM

The abdominal incision for specimen extraction could trigger postoperative pain after laparoscopic colorectal resections (LCRs). Continuous wound infusion (CWI) of ropivacaine may be a valuable option for postoperative analgesia. This study was undertaken to evaluate the potential benefits of ropivacaine CWI on pain relief, metabolic stress reaction, prevention of wound hyperalgesia and residual incisional pain after LCR. A subgroup with intravenous lidocaine infusion (IVL) was added to discriminate between the peripheral and systemic effects of local anaesthetic infusions.

METHOD

Patients were randomly allocated to three subgroups: CWI (0.2% ropivacaine 10 ml/h for 48 h); IVL (lidocaine 1.5% at 4 ml/h for 48 h); control group.

RESULTS

In all, 95 patients were randomized (86 patients analysed). Postoperative pain intensity did not differ significantly between groups. Within the first 24 h after surgery, morphine requirement was significantly lower in the CWI group compared with the IVL group, but there was no significant difference compared with the control group (P = 0.02 and P = 0.15, respectively). The area of hyperalgesia did not differ significantly between subgroups, nor did the hyperalgesia ratio which was 1.2 cm (0.0-6.7) vs 1.9 cm (0.4-4.0) vs 2.0 cm (0.5-7.0) in the CWI, IVL and control groups respectively (P = 0.35). The number of patients reporting residual incisional pain after 3 months (3/26 vs 4/23 vs 4/23 in the CWI, IVL and control groups respectively) did not differ significantly between the groups, nor did their metabolic stress reactions.

CONCLUSION

Ropivacaine CWI at the site of the abdominal incision did not provide any significant benefit either on analgesia or on the prevention of wound hyperalgesia after LCR.

Pre-emptive multimodal analgesia with tramadol and ketamine-lidocaine infusion for suppression of central sensitization in a dog model of ovariohysterectomy

Objectives

The effects of pre-emptive infusion of ketamine-lidocaine with tramadol on the suppression of central sensitization were investigated in a dog ovariohysterectomy model.

Patients and methods

Twelve dogs were randomly assigned to two groups: ketamine-lidocaine-tramadol (KLT) and tramadol (T) groups. Both groups received intravenous tramadol 4 mg/kg body weight as premedication. Immediately after induction, the KLT group received ketamine and lidocaine at 0.5 and 2 mg/kg loading dose, followed by continuous rate infusion of 50 and 100 µg/kg/min, respectively, for 2 hours. Dogs in T group received saline bolus and continuous rate infusion at equi-volume. Intraoperatively, hemodynamic responses to surgical stimulation were recorded, whereas postoperative pain was evaluated using an algometer and short form of the Glasgow composite measure pain scale.

Results

Intraoperatively, hemodynamic responses to surgical stimulation were obtunded to a greater degree in KLT compared to T group. Postoperatively, the pain scores increased only for the first hour in KLT group, compared to 12 hours in T group. Mechanical thresholds at the abdomen decreased postoperatively between 12 and 60 hours in KLT group versus the entire 72 hours in T group. Thresholds at tibia and radius in both groups increased in the immediate 1 hour postoperatively, but decreased thereafter. Significant decrement of thresholds from baseline were detected in the tibia at 24, 42, and 60 hours in KLT group compared to 24-72 hours in T group, and in the radius between 36 and 48 hours in T group, but none in KLT group.

Conclusion

Addition of pre-emptive ketamine-lidocaine infusion to single intravenous dose of tramadol enhanced attenuation of central sensitization and improved intra- and postoperative analgesia.

A randomized crossover study of the effects of lidocaine on motor- and sensory-evoked potentials during spinal surgery

BACKGROUND CONTEXT

Lidocaine has emerged as a useful adjuvant anesthetic agent for cases requiring intraoperative monitoring of motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SSEPs). A previous retrospective study suggested that lidocaine could be used as a component of propofol-based intravenous anesthesia without adversely affecting MEP or SSEP monitoring, but did not address the effect of the addition of lidocaine on the MEP and SSEP signals of individual patients.

PURPOSE

The purpose of this study was to examine the intrapatient effects of the addition of lidocaine to balanced anesthesia on MEPs and SSEPs during multilevel posterior spinal fusion.

STUDY DESIGN

This is a prospective, two-treatment, two-period crossover randomized controlled trial with a blinded primary outcome assessment.

PATIENT SAMPLE

Forty patients undergoing multilevel posterior spinal fusion were studied.

OUTCOME MEASURES

The primary outcome measures were MEP voltage thresholds and SSEP amplitudes. Secondary outcome measures included isoflurane concentrations and hemodynamic parameters.

METHODS

Each participant received two anesthetic treatments (propofol 50 mcg/kg/h and propofol 25 mcg/kg/h+lidocaine 1 mg/kg/h) along with isoflurane, ketamine, and diazepam. In this manner, each patient served as his or her own control. The order of administration of the two treatments was determined randomly.

RESULTS

There were no significant within-patient differences between MEP threshold voltages or SSEP amplitudes during the two anesthetic treatments.

CONCLUSIONS

Lidocaine may be used as a component of balanced anesthesia during multilevel spinal fusions without adversely affecting the monitoring of SSEPs or MEPs in individual patients.

Clinical Efficacy of Intravenous Lidocaine for Thyroidectomy: A Prospective, Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Systemic lidocaine has analgesic and anti-inflammatory effects. The purpose of this prospective, randomized, double-blind study was to evaluate the effects of intravenous lidocaine on pain following thyroidectomy.

METHODS

Fifty-eight adult patients scheduled for total thyroidectomy were randomly allocated to receive a 1.5 mg/kg lidocaine bolus followed by a 2 mg/kg/h infusion during surgery, or the same volume of normal saline (control). After thyroidectomy, we evaluated postoperative pain, nausea, fentanyl consumption, frequency of pushing the button (FPB) for patient-controlled analgesia (PCA), High-sensitivity C-reactive protein (hs-CRP) in serum, and patient satisfaction scores regarding the recovery process.

RESULTS

Postoperative pain and nausea scores were significantly lower in the lidocaine group for the first 4 h following thyroidectomy, compared to the control group. Fentanyl consumption and FPB for the PCA were also significantly reduced in the lidocaine group for 4 h following thyroidectomy, and hs-CRP was significantly less in the lidocaine group at postoperative days 1 and 3. Furthermore, satisfaction scores were significantly higher in the lidocaine group compared to the control group.

CONCLUSIONS

Intravenous lidocaine effectively reduced postoperative pain and nausea following thyroidectomy as well as improved the quality of recovery.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov NCT01608360.

A comparison between intravenous lidocaine and ketamine on acute and chronic pain after open nephrectomy: A prospective, double-blind, randomized, placebo-controlled study

BACKGROUND

Recently, there has been increasing interest in the use of analgesic adjuncts such as intravenous (IV) ketamine and lidocaine.

OBJECTIVES

To compare the effects of perioperative IV lidocaine and ketamine on morphine requirements, pain scores, quality of recovery, and chronic pain after open nephrectomy.

STUDY DESIGN

A prospective, randomized, placebo-controlled, double-blind trial.

SETTINGS

The study was conducted in Charles Nicolle University Hospital of Tunis.

METHODS

Sixty patients were randomly allocated to receive IV lidocaine: bolus of 1.5 mg/kg at the induction of anesthesia followed by infusion of 1 mg/kg/h intraoperatively and for 24 h postoperatively or ketamine: bolus of 0.15 mg/kg followed by infusion of 0.1 mg/kg/h intraoperatively and for 24 h postoperatively or an equal volume of saline (control group [CG]).

MEASUREMENTS

Morphine consumption, visual analog scale pain scores, time to the first passage of flatus and feces, postoperative nausea and vomiting (PONV), 6-min walk distance (6MWD) at discharge, and the incidence of chronic neuropathic pain using the "Neuropathic Pain Questionnaire" at 3 months.

RESULTS

Ketamine and lidocaine reduced significantly morphine consumption (by about 33% and 42%, respectively) and pain scores compared with the CG (P < 0.001). Lidocaine and ketamine also significantly improved bowel function in comparison to the CG (P < 0.001). Ketamine failed to reduce the incidence of PONV. The 6 MWD increased significantly from a mean ± standard deviation of 27 ± 16.2 m in the CG to 82.3 ± 28 m in the lidocaine group (P < 0.001). Lidocaine, but not ketamine, reduced significantly the development of neuropathic pain at 3 months (P < 0.05).

CONCLUSION

Ketamine and lidocaine are safe and effective adjuvants to decrease opioid consumption and control early pain. We also suggest that lidocaine infusion serves as an interesting alternative to improve the functional walking capacity and prevent chronic neuropathic pain at 3 months after open nephrectomy.

Effects on hemodynamic variables and echocardiographic parameters after a stellate ganglion block in 15 healthy volunteers

BACKGROUND

The sympathetic nervous system has an important role in generating pain. Various pathomechanisms are involved that respond well to the application of local anesthetics (LA), for example to the stellate ganglion block (SGB).

OBJECTIVES

We wanted to know more about the effects of SGB on cardiovascular parameters.

METHODS

We included 15 healthy volunteers; another 15 healthy volunteers as a control group (sham injection of LA). In order to produce a more precise SGB, we employed only a small volume of LA (3mL), a LA with a lower permeability (procaine 1%), and a modified injection technique. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and echocardiographic parameters were recorded before and after SGB. We also investigated whether there are side differences (left and right SBG).

RESULTS

At baseline all parameters were within the normal range. After performing right and left SGB DBP significantly increased (on the right side from 68.73±8.61 to 73.53±11.10, p=0.015; on the left side from 70.66±13.01 to 77.93±10.40, p=0.003). In the control group no increase in DBP was observed. No side-specific differences were found, except a significant reduction in the maximum velocity of myocardial contraction during the systole with left-sided SGB.

CONCLUSIONS

Even with our methods we could not prevent the simultaneous occurrence of a partial parasympatholytic effect. For this reason, the SGB has only minor hemodynamic effects, which is desirable as it enhances the safety of the SGB.

Lidocaine versus ropivacaine for postoperative continuous paravertebral nerve blocks in patients undergoing laparoscopic bowel surgery: a randomized, controlled, double-blinded, pilot study

Background and objectives

Lidocaine could provide many advantages in continuous regional anesthesia techniques, including faster onset, greater titratability, and lower cost than long-acting local anesthetics. This prospective, randomized, double-blinded, pilot study is therefore intended to compare lidocaine to ropivacaine in bilateral continuous paravertebral blocks using a multimodal approach for postoperative pain management following laparoscopic bowel surgery.

Methods

Thirty-five ASA I–III consecutive patients undergoing elective laparoscopic bowel surgery and bilateral thoracic paravertebral continuous blocks were analyzed: bilateral thoracic paravertebral infusions of ropivacaine 0.2% (Group Ropi, n=18) or lidocaine 0.25% (Group Lido, n=17) were started at 7 mL/h in the postanesthesia care unit. For each patient, we collected numerical rating scores (NRS) for pain at rest and during movement at baseline, at postanesthesia care unit discharge, at 24 hours and 48 hours after the end of surgery, as well as hydromorphone patient-controlled analgesia requirements, local anesthetic consumption, side effects, postoperative complications, and functional outcomes.

Results

No effect of group distribution on NRS scores for pain at rest or at movement (P=0.823 and P=0.146), nor on hydromorphone (P=0.635) or local anesthetic consumption (P=0.063) was demonstrated at any analyzed time point. Hospital length of stay and spontaneous ambulation were comparable between groups (P=0.636 and P=0.148). In the context of a multimodal approach, the two drugs showed comparable safety profiles.

Discussion

Lidocaine 0.25% and ropivacaine 0.2% provided similar analgesic profiles after elective abdominal surgeries, without any difference in terms of functional outcomes. The easier titratability of lidocaine together with its lower cost induced our clinical practice to definitely switch from ropivacaine to lidocaine for postoperative bilateral paravertebral continuous infusions.

Comparison of the efficacy of saline, local anesthetics, and steroids in epidural and facet joint injections for the management of spinal pain: A systematic review of randomized controlled trials

BACKGROUND

The efficacy of epidural and facet joint injections has been assessed utilizing multiple solutions including saline, local anesthetic, steroids, and others. The responses to these various solutions have been variable and have not been systematically assessed with long-term follow-ups.

METHODS

Randomized trials utilizing a true active control design were included. The primary outcome measure was pain relief and the secondary outcome measure was functional improvement. The quality of each individual article was assessed by Cochrane review criteria, as well as the criteria developed by the American Society of Interventional Pain Physicians (ASIPP) for assessing interventional techniques. An evidence analysis was conducted based on the qualitative level of evidence (Level I to IV).

RESULTS

A total of 31 trials met the inclusion criteria. There was Level I evidence that local anesthetic with steroids was effective in managing chronic spinal pain based on multiple high-quality randomized controlled trials. The evidence also showed that local anesthetic with steroids and local anesthetic alone were equally effective except in disc herniation, where the superiority of local anesthetic with steroids was demonstrated over local anesthetic alone.

CONCLUSION

This systematic review showed equal efficacy for local anesthetic with steroids and local anesthetic alone in multiple spinal conditions except for disc herniation where the superiority of local anesthetic with steroids was seen over local anesthetic alone.

Benefits of intravenous lidocaine on post-operative pain and acute rehabilitation after laparoscopic nephrectomy

BACKGROUND AND AIMS

Intravenous (I.V.) lidocaine has analgesic, antihyperalgesic and anti-inflammatory properties and is known to accelerate the return of bowel function after surgery. We evaluated the effects of I.V. lidocaine on pain management and acute rehabilitation protocol after laparoscopic nephrectomy.

MATERIALS AND METHODS

A total of 47 patients scheduled to undergo laparoscopic nephrectomy were included in a two-phase observational study where I.V. lidocaine (1.5 mg/kg/h) was introduced, in the second phase, during surgery and for 24 h post-operatively. All patients underwent the same post-operative rehabilitation program. Post-operative pain scores, opioid consumption and extent of hyperalgesia were measured. Time to first flatus and 6 min walking test (6MWT) were recorded.

RESULTS

Patient demographics were similar in the two phases (n = 22 in each group). Lidocaine significantly reduced morphine consumption (median [25-75% interquartile range]; 8.5 mg[4567891011121314151617] vs. 25 mg[1920212223242526272829303132]; P < 0.0001), post-operative pain scores (P < 0.05) and hyperalgesia extent on post-operative day 1-day 2-day 4 (mean ± standard deviation (SD); 1.5 ± 0.9 vs. 4.3 ± 1.2 cm (P < 0.001), 0.6 ± 0.5 vs. 2.8 ± 1.2 cm (P < 0.001) and 0.13 ± 0.3 vs. 1.2 ± 1 cm (P < 0.001), respectively). Time to first flatus (mean ± SD; 29 ± 7 h vs. 48 ± 15 h; P < 0.001) and 6MWT at day 4 (189 ± 50 m vs. 151 ± 53 m; P < 0.001) were significantly enhanced in patients with i.v. lidocaine.

CONCLUSION

Intravenous (I.V.) lidocaine could reduce post-operative morphine consumption and improve post-operative pain management and post-operative recovery after laparoscopic nephrectomy. I.V. lidocaine could contribute to better post-operative rehabilitation.

Partial intravenous anaesthesia in the horse: a review of intravenous agents used to supplement equine inhalation anaesthesia. Part 1: lidocaine and ketamine

OBJECTIVE

To review the literature with regard to the use of different intravenous agents as supplements to inhalational anaesthesia in horses. These drugs include lidocaine, ketamine, opioids and α2 -agonists. The Part 1 of this review will focus in the use of lidocaine and ketamine.

DATABASES USED

Pubmed & Web of Science. Search terms: horse, inhalant anaesthesia, balanced anaesthesia, partial intravenous anaesthesia, lidocaine, ketamine.

CONCLUSIONS

Different drugs and their combinations can be administered systemically in anaesthetized horses, with the aim of reducing the amount of the volatile agent whilst improving the recovery qualities and providing a multimodal analgesic approach. However, full studies as to whether these techniques improve cardiopulmonary status are not always available and potential disadvantages should also be considered.

Systemic ropivacaine diminishes pain sensitization processes: a randomized, double-blinded, placebo-controlled, crossover study in healthy volunteers

Introduction

Ropivacaine is a local anesthetic widely used for regional anesthesia. One of its advantages is low toxicity at plasma concentrations reached systemically during continuous peripheral or central nervous block. The objective of this study was to test the effect of systemic ropivacaine on pain, hyperalgesia, dynamic allodynia, and flare response.

Methods

This randomized, double-blinded, placebo-controlled, crossover study was carried out in at the Clinical Trials Centre, University of Zurich, Switzerland. Twenty healthy male volunteers were included in the study. Exclusion criteria were contraindications or hypersensitivity to local anesthetics, vulnerable subjects (intellectually or mental impaired), drug, alcohol or nicotine abuse, known peripheral neuropathies, diabetes mellitus and/or congestive heart disease. Ropivacaine and saline were infused intravenously during a subcutaneous electrical stimulation. The stimulation software adjusted the stimulus strength according to the rating on a numeric rating scale (NRS; 0–10) maintaining a NRS of 5. Areas of punctate hyperalgesia, dynamic allodynia, and flare response were measured before and after the infusion.

Results

The area of hyperalgesia increased significantly with saline (303 ± 380%, P < 0.05) and ropivacaine (186 ± 137%, P < 0.05). The area of allodynia (253 ± 299%, P < 0.05) and flare response (112 ± 24%, P < 0.05) increased only during the placebo infusion.

Conclusion

The results of this study imply that systemic ropivacaine may diminish pain sensitization processes.

Electronic supplementary material

The online version of this article (doi:10.1007/s40122-013-0021-z) contains supplementary material, which is available to authorized users.

Effect of Perioperative Intravenous Lidocaine Administration on Pain, Opioid Consumption, and Quality of Life after Complex Spine Surgery

Background:

The authors tested the primary hypothesis that perioperative IV lidocaine administration during spine surgery (and in the postanesthesia care unit for no more than 8 h) decreases pain and/or opioid requirements in the initial 48 postoperative hours. Secondary outcomes included major complications, postoperative nausea and vomiting, duration of hospitalization, and quality of life.

Methods:

One hundred sixteen adults having complex spine surgery were randomly assigned to perioperative IV lidocaine (2 mg·kg−1·h−1) or placebo during surgery and in the postanesthesia care unit. Pain was evaluated with a verbal response scale. Quality of life at 1 and 3 months was assessed using the Acute Short-form (SF) 12 health survey. The authors initially evaluated multivariable bidirectional noninferiority on both outcomes; superiority on either outcome was then evaluated only if noninferiority was established.

Results:

Lidocaine was significantly superior to placebo on mean verbal response scale pain scores (P &lt; 0.001; adjusted mean [95% CI] of 4.4 [4.2-4.7] and 5.3 [5.0-5.5] points, respectively) and significantly noninferior on mean morphine equivalent dosage (P = 0.011; 55 [36-84] and 74 [49-111] mg, respectively). Postoperative nausea and vomiting and the duration of hospitalization did not differ significantly. Patients given lidocaine had slightly fewer 30-day complications than patients given placebo (odds ratio [95% CI] of 0.91 [0.84–1.00]; P = 0.049). Patients given lidocaine had significantly greater SF-12 physical composite scores than placebo at 1 (38 [31–47] vs. 33 [27–42]; P = 0.002) and 3 (39 [31–49] vs. 34 [28–44]; P = 0.04) months, postoperatively.

Conclusion:

IV lidocaine significantly improves postoperative pain after complex spine surgery.

The effect of perioperative intravenous lidocaine and ketamine on recovery after abdominal hysterectomy

BACKGROUND

Perioperative ketamine infusion reduces postoperative pain; perioperative lidocaine infusion reduces postoperative narcotic consumption, speeds recovery of intestinal function, improves postoperative fatigue, and shortens hospital stay. However, it is unknown whether perioperative IV lidocaine and/or ketamine enhances acute functional recovery. We therefore tested the primary hypothesis that perioperative IV lidocaine and/or ketamine in patients undergoing open abdominal hysterectomy improves rehabilitation as measured by a 6-minute walk distance (6-MWD) on the second postoperative morning.

METHODS

Women having open hysterectomy were anesthetized with sevoflurane, followed by patient-controlled morphine. Patients were factorially randomized to one of the following groups: (1) lidocaine and placebo, (2) placebo and ketamine, (3) placebo and placebo, or (4) lidocaine and ketamine. Lidocaine was given as a bolus (1.5 mg/kg), followed by lidocaine infusion of 2 mg/kg/h for the first 2 hours, and then 1.2 mg/kg/h for 24 postoperative hours. Ketamine was given as a bolus (0.35 mg/kg), followed by ketamine infusion of 0.2 mg/kg/h for the first 2 hours, and then 0.12 mg/kg/h for 24 postoperative hours. The primary double-blind outcome was 6-MWD on the second postoperative morning; secondary outcomes included pain scores, opioid consumption, postoperative nausea and vomiting, and fatigue score.

RESULTS

The study was stopped after a planned interim analysis of 64 patients showed that lidocaine crossed the preplanned futility boundary, with mean ± SD of 202 ± 66 m versus 202 ± 73 m for lidocaine versus placebo, respectively, and mean difference (interim adjusted 97.5% confidence interval) of 0.93 m (-52, 54) (P = 0.96); the ketamine effect also crossed the futility boundary, with mean ± SD of 193 ± 77 m versus 210 ± 61 m for ketamine versus placebo, respectively, and mean difference (interim adjusted 97.5% confidence interval) of -11 m (-65, 44) (P = 0.54). No interaction between the 2 intervention effects was observed (P = 0.96). Neither intervention significantly influenced any of the secondary outcomes.

CONCLUSION

Our results do not support use of lidocaine or ketamine for improving 6-MWD on the second postoperative day after open hysterectomy.

Perioperative nerve blockade: clues from the bench

Peripheral and neuraxial nerve blockades are widely used in the perioperative period. Their values to diminish acute postoperative pain are established but other important outcomes such as chronic postoperative pain, or newly, cancer recurrence, or infections could also be influenced. The long-term effects of perioperative nerve blockade are still controversial. We will review current knowledge of the effects of blocking peripheral electrical activity in different animal models of pain. We will first go over the mechanisms of pain development and evaluate which types of fibers are activated after an injury. In the light of experimental results, we will propose some hypotheses explaining the mitigated results obtained in clinical studies on chronic postoperative pain. Finally, we will discuss three major disadvantages of the current blockade: the absence of blockade of myelinated fibers, the inappropriate duration of blockade, and the existence of activity-independent mechanisms.

Effect of systemic lidocaine on visceral and somatic nociception in conscious horses

REASONS FOR PERFORMING STUDY

Commonly used analgesics (nonsteroidal anti-inflammatory agents, opioids and alpha2-agonists) have unwanted side effects. An effective alternative with minimal adverse effects would benefit clinical equine pain management.

OBJECTIVES

To compare the effect of lidocaine or saline on duodenal and rectal distension threshold pressure and somatic thermal threshold in conscious mature horses.

HYPOTHESIS

Systemically administered lidocaine would increase somatic and visceral nociceptive thresholds.

METHODS

Lidocaine (2 mg/kg bwt bolus followed by 50 microg/kg bwt/min for 2 h) or saline was administered to 6 horses each carrying a permanently implanted gastric cannula, in a randomised, blinded cross-over design. Thermal threshold was measured using a probe containing a heater element placed over the withers which supplied heat until the horse responded. A barostatically controlled intraduodenal balloon was distended until a discomfort response was obtained. A rectal balloon was inflated until extruded or signs of discomfort noted.

RESULTS

Thermal threshold was increased significantly 30 and 90 mins after the start of lidocaine infusion. There was no change in duodenal distension pressure and a small but clinically insignificant change in colorectal distension pressure in the lidocaine group.

CONCLUSIONS

At the dose used, systemically administered lidocaine produced thermal antinociception but minimal changes in visceral nociception.

POTENTIAL RELEVANCE

At these doses, lidocaine may play a role in somatic analgesia in horses.

The effect of perioperative intravenous lidocaine on postoperative pain and immune function

BACKGROUND

Surgery-associated tissue injury leads to nociception and inflammatory reaction, accompanied by increased production of proinflammatory cytokines. These cytokines can induce peripheral and central sensitization, leading to pain augmentation. Recently, a frequently used local anesthetic, lidocaine, was introduced as a part of a perioperative pain management technique. In addition to its analgesic effects, lidocaine has an antiinflammatory property, decreasing the upregulation of proinflammatory cytokines. We focused on the effects of preincisional and intraoperative IV lidocaine on pain intensity and immune reactivity in the postoperative period.

METHODS

Sixty-five female patients (ASA physical status I-II) scheduled for transabdominal hysterectomy were recruited to this randomized, placebo-controlled study. Thirty-two patients in the treatment group received IV lidocaine starting 20 min before surgery, whereas the control group (33 patients) received a matched saline infusion. Both groups received patient-controlled epidural analgesia during the postoperative period. Blood samples were collected before, 24, 48, and 72 h after surgery to measure ex vivo cytokine production of interleukin (IL)-1 receptor antagonist (IL-1ra) and IL-6, as well lymphocyte mitogenic response to phytohemagglutinin-M. A 10-cm visual analog scale was used to assess pain intensity at rest and after coughing.

RESULTS

Patients in the lidocaine + patient-controlled epidural analgesia group experienced less severe postoperative pain in the first 4 and 8 h after surgery (visual analog scale 4/3.7 at rest and 5.3/5 during coughing versus 4.5/4.2 and 6.1/5.3, respectively, in the placebo group). There was significantly less ex vivo production of IL-1ra and IL-6, whereas the lymphocyte proliferation response to phytohemagglutinin-M was better maintained than in the control group.

CONCLUSION

The present findings indicate that preoperative and intraoperative IV lidocaine improves immediate postoperative pain management and reduces surgery-induced immune alterations.

The effect of a peripheral block on inflammation-induced prostaglandin E2 and cyclooxygenase expression in rats

BACKGROUND

Peripheral inflammatory pain is associated with an upregulation of spinal cord COX-2 (cyclooxygenase-2), with a subsequent increase in central prostaglandin E2 (PGE2) levels associated with the development of hyperalgesia. In this study, we evaluated the effect of bupivacaine administered via a nerve block or via a systemic route on the spinal expression of PGE2 and COX in a model of peripheral inflammation in rats.

METHODS

All rats randomly received three injections: 1) a left subcutaneous hindpaw injection (0.2 mL with either carrageenan 2% w/v or saline), 2) a left sciatic block (0.2 mL with either bupivacaine 0.5% or saline), and 3) a systemic injection (subcutaneous interscapular with 0.2 mL with either bupivacaine 0.5% or saline). Local edema, thermal, and mechanical hyperalgesia as well as cerebrospinal fluid PGE2 concentration and COX-1 and COX-2 expression in the spinal cord in dorsal root ganglions were measured.

RESULTS

We confirmed that a bupivacaine block attenuates hyperalgesia and local inflammation in a model of inflammatory pain. This effect was associated with an inhibition of the increase in COX-2 expression induced by peripheral inflammation in dorsal root ganglions and cord. The subsequent production of PGE2 in cerebrospinal fluid was also impaired. Systemic bupivacaine did not modify either the hyperalgesia and local inflammation or COX expression.

CONCLUSION

These results constitute a key element strongly suggesting that local anesthetics act at a different level when administered systematically or via a nerve block.

Chronic whiplash and central sensitization; an evaluation of the role of a myofascial trigger points in pain modulation

Objective

it has been established that chronic neck pain following whiplash is associated with the phenomenon of central sensitization, in which injured and uninjured parts of the body exhibit lowered pain thresholds due to an alteration in central pain processing. it has furthermore been hypothesized that peripheral sources of nociception in the muscles may perpetuate central sensitization in chronic whiplash. the hypothesis explored in the present study was whether myofascial trigger points serve as a modulator of central sensitization in subjects with chronic neck pain.

Design

controlled case series.

Setting

outpatient chronic pain clinic.

Subjects

seventeen patients with chronic and intractable neck pain and 10 healthy controls without complaints of neck pain.

Intervention

symptomatic subjects received anesthetic infiltration of myofascial trigger points in the upper trapezius muscles and controls received the anesthetic in the thigh.

Outcome measures: pre and post injection cervical range of motion, pressure pain thresholds (ppt) over the infraspinatus, wrist extensor, and tibialis anterior muscles. sensitivity to light (photophobia) and subjects' perception of pain using a visual analog scale (vas) were also evaluated before and after injections. only the ppt was evaluated in the asymptomatic controls.

Results

immediate (within 1 minute) alterations in cervical range of motion and pressure pain thresholds were observed following an average of 3.8 injections with 1–2 cc of 1% lidocaine into carefully identified trigger points. cervical range of motion increased by an average of 49% (p = 0.000) in flexion and 44% (p = 0.001) in extension, 47% (p = 0.000) and 28% (p < 0.016) in right and left lateral flexion, and a 27% (p = 0.002) and 45% (p = 0.000) in right and left rotation. ppt were found increased by 68% over the infraspinatus (p = 0.000), by 78% over the wrist extensors (p = 0.000), and by 64% over the tibialis anterior (p = 0.002). among 11 subjects with photophobia, only 2 remained sensitive to light after the trigger point injections (p = 0.033). average vas dropped by 57%, from 6.1 to 2.6 (p = 0.000). no significant changes in ppt were observed in the control group following lidocaine infiltration of the thigh.

Conclusion

the present data suggest that myofascial trigger points serve to perpetuate lowered pain thresholds in uninjured tissues. additionally, it appears that lowered pain thresholds associated with central sensitization can be immediately reversed, even when associated with long standing chronic neck pain. although the effects resulting from anesthesia of trigger points in the present study were temporary, it is possible that surgical excision or ablation of the same trigger points may offer more permanent solutions for chronic neck pain patients. further study is needed to evaluate these and other options for such patients.

[Effect of local anesthetics on the postoperative inflammatory response]

Current knowledge suggests that peripheral inflammation following surgery activates and sensitizes both peripheral and central nervous system. These phenomena involved in the maintenance of the inflammatory response lead to hypersensibility, hyperalgesia and allodynia. Hyperalgesia participates in the general experience of postoperative pain and ALo in the development of chronic pain. A correlation between the ability of treatments to reduce areas of hypersensitivity surrounding the wound after surgery and their ability to reduce the incidence of chronic pain has been shown. For a long time, local anaesthetics have been used for their capacity to block nociceptive input. They can ALo modulate the inflammatory response following a surgical trauma. By inhibiting the nervous conductivity at the site of the trauma, local anesthetics attenuate the sensitization of the nervous system and therefore the inflammatory phenomena. They ALo exert intrinsic anti-inflammatory properties by modulating the local and systemic liberation of inflammatory mediators. The mechanisms involved are not clearly elucidated. Local, systemic, and spinal inflammatory mechanisms may be influenced by local anesthetics through multiple different mechanisms. The therapeutic implications of effects of local anesthetics on local, systemic, and spinal inflammatory responses merit further study.

A phase II pilot study to evaluate use of intravenous lidocaine for opioid-refractory pain in cancer patients

Opioid-refractory pain is distressing because it is notoriously difficult to treat. Relief from adjuvant therapies often occurs after a lag time. Retrospective evidence points to a role for intravenous (IV) lidocaine in this setting for pain relief. This study was planned as a randomized, double-blind, placebo-controlled, crossover study in which eligible patients received both lidocaine and placebo infusions separated by two weeks. Primary endpoints were magnitude and duration of pain relief. Fifty patients were included in the study. Pain relief was significantly better (P<0.001) and more patients reported a decrease in analgesic requirements (P=0.0012) after lidocaine infusion than after placebo. Onset of analgesia was noted at a mean of 40+/-16.28 minutes after initiation of infusion of IV lidocaine. Mean duration of this analgesia, 9.34+/-2.58 days after the single infusion, was significantly longer than that for placebo (P<0.01). Side effects observed were tinnitus, perioral numbness, sedation, light-headedness, and headache. All side effects were self-limited and did not require any intervention except termination of lidocaine infusion in one case. These data demonstrate that a single IV infusion of lidocaine provided a significantly greater magnitude and duration of pain relief than placebo infusion in opioid-refractory patients with cancer pain. Side effects were tolerable. It is thus a promising modality worth investigating further to establish guidelines for its use in cancer patients with opioid-refractory pain.

Antiinflammatory effect of peripheral nerve blocks after knee surgery: clinical and biologic evaluation

BACKGROUND

Nerve blocks provide analgesia after surgery. The authors tested whether nerve blocks have antiinflammatory effects.

METHODS

Patients had combined sciatic (single-shot) and continuous femoral block (48 h) (block group) or morphine patient-controlled analgesia after total knee arthroplasty. Pain at rest and upon movement was monitored at 1 (D1), 4 (D4), and 7 days (D7) and 1 (M1) and 3 months (M3) after surgery. Knee inflammation was evaluated (skin temperature, knee circumference) before surgery and at D1, D4, D7, M1, and M3. Plasma cytokine concentrations (interleukin [IL]-6, IL-1beta, tumor necrosis factor [TNF], IL-10, soluble receptor 1 of TNF [sTNF-R1]) were measured before surgery and at 4 h, D1, D4, and D7 after surgery. Capsule and synovial membrane cytokines were measured (IL-6, TNF, IL-1, IL-10). Knee flexion was evaluated before surgery and at D1, D4, D7, M1, and M3. Morphine use and recovery time to autonomy were monitored.

RESULTS

Pain at rest and upon movement was lower in the block group than in patient-controlled analgesia patients between D1 and D7 (analysis of variance, P < 0.005). Knee flexion was improved in the block group for D1 to M1 (analysis of variance, P < 0.0001). Block group patients recovered nonassisted mobilization (t test, P = 0.04) and toilet use (t test, P = 0.03) more rapidly. Knee circumference and skin temperature were lower in the block group between D1 and D7 (analysis of variance, P < 0.05). Synovial membrane IL-1 (P < 0.05) and IL-10 (P < 0.01) increased, and plasma IL-6 and sTNF-R1 peaked at 24 h, with no difference between groups.

CONCLUSION

Nerve blocks inhibited clinical inflammation after total knee arthroplasty, with no change in tissue and plasma cytokine concentrations.