The Efficacy of Systemic Lidocaine in the Management of Chronic Pain: A Literature Review

Intravenous Lidocaine for the Management of Chronic Pain: A Narrative Review of Randomized Clinical Trials

Background

Chronic pain remains a serious health problem with significant impact on morbidity and well-being. Available treatments have only resulted in relatively modest efficacy. Thus, novel therapeutic treatments with different mechanisms have recently generated empirical interest. Lidocaine is postulated to provide anti-inflammatory and anti-nociceptive effect through its action at the N-methyl-D-aspartate (NMDA) and voltage gated calcium receptors. Emerging research indicates that lidocaine could be a reasonable alternative for treating chronic pain.

Objective

Considering the evidence surrounding lidocaine's potential as a therapeutic modality for chronic pain, we conducted a narrative review on the evidence of lidocaine's therapeutic effects in chronic pain.

Methods

A review of the PubMed, and Google scholar databases was undertaken in May 2022 to identify completed studies that investigated the effectiveness of lidocaine in the treatment of chronic pain from database inception to June 2022.

Results

A total of 25 studies were included in the narrative review. Findings on available studies suggest that intravenous infusion of lidocaine is an emerging and promising option that may alleviate pain in some clinical populations. Our narrative synthesis showed that evidence for intravenous lidocaine is currently mixed for a variety of chronic pain syndromes. Findings indicate that evidence for efficacy is limited for: CRPS, and cancer pain. However, there is good evidence supporting the efficacy of intravenous lidocaine as augmentation in chronic post-surgical pain.

Conclusion

Lidocaine may be a promising pharmacologic solution for chronic pain. Future investigation is warranted on elucidating the neurobiological mechanisms of lidocaine in attenuating pain signaling pathways.

Long-term pain outcomes after serial lidocaine infusion in participants with recent onset of peripheral neuropathic pain: A pilot double-blind, randomized, placebo-controlled trial

BACKGROUND

This study investigated the outcomes up to 12 weeks after serial lidocaine infusion for early-onset peripheral neuropathic pain.

METHODS

This pilot double-blind, randomized, 2-arm placebo-controlled trial recruited 50 participants with onset of peripheral neuropathic pain within the past 6 months and randomized them to either receive lidocaine (3 mg/kg) in normal saline (50 mL) intravenous infusion over 1 hour (lidocaine group) once a week for 4 weeks or 50 mL of normal saline infusion (placebo group) once a week for 4 weeks. Twenty-nine participants completed the protocol; 15 participants were assigned to the lidocaine group and 14 to the placebo group. The outcomes were pain intensity assessed using a numerical rating scale (NRS), quality of life assessed using EuroQol-Five Dimensions-Five Levels questionnaire (EQ-5D-5L), psychological function using the Thai version of the 21-item Depression Anxiety Stress Scales (DASS-21), pain medication use, and adverse effects, all assessed at baseline (BL) and again at 4, 8, and 12 weeks following randomization.

RESULTS

The reported tramadol use at 8 and 12 weeks following the first infusion was significantly lower in the lidocaine group (P = .023). No other significant between-group differences were observed at any time point or for any other outcome, and no serious adverse events were observed.

CONCLUSION

Multiple lidocaine infusions of 3 mg/kg once a week for 4 weeks in participants with recent onset of peripheral neuropathic pain demonstrated no significant benefits in pain intensity, quality of life, or psychological outcomes. At most, this treatment may result in less tramadol use.

Hamular bursitis as a cause of orofacial pain. A case report

Pterygoid hamular bursitis is an infrequent cause of orofacial pain due to a hypertrophic pterygoid hamulus. The pain is often referred to the pharynx, temporomandibular region and facial zone, and requires a differential diagnosis with other craniofacial entities. This paper describes a patient with pterygoid hamular bursitis that presented pain of neuropathic characteristics in the left retromolar region, associated with odynophagia and temporomandibular joint disorders. Based on the clinical and radiological findings, a surgical resection of the pterygoid hamulus was decided. After the surgical procedure the patient still reported symptoms so additional specific treatments such as peripheral nerve block and infiltration were performed. Four months later, the patient developed a squamous cell carcinoma on the left margin of the tongue, which was surgically treated. At present (thirty months follow-up), the patient has no pain or signs of tumor relapse. Key words:Pterygoid hamular bursitis, orofacial pain, oral carcinoma, temporomandibular joint disorders, radiofrequency, neuropathic pain.

In vitro and in vivo evaluation of a novel lidocaine-loaded cubosomal gel for prolonged local anesthesia

Marketed lidocaine dosage forms (such as ointment, gels, and injections) used to manage acute and chronic pain showed a short duration of action (<2 h). In this study, a lidocaine-loaded cubosomal gel was prepared to sustain the release of lidocaine to prolong the local anesthetic effect (high drug retention in the skin). Lidocaine-loaded cubosomal gels were prepared by melt emulsification and sonication using Pluronic F127 and DL-α-monoolein (at different levels). The cubosomal gels were characterized by morphology, size, zeta potential, entrapment efficacy, assay, viscosity, pH, and texture profiles. Ex vivo lidocaine permeation and retention studies were performed using Sprague–Dawley rat skin. Transmission electron microscopy images confirmed the bi-continuous liquid crystalline phase with a honeycomb cubosome structure. The cubosomal particle size (103–227 nm), viscosity (13,524–15,627cp), and entrapment efficacy (78.4–94.7%) increase with the level of monoolein. The ex-vivo permeation study showed a biphasic release pattern, with lidocaine cleared from ointment within 4 h (97.9% cumulative release), while cubosomal gels showed sustained release up to 24 h (53.33–98.86% cumulative release). A skin retention study demonstrated that cubosomes can increase (up to 28-fold) the lidocaine content in the skin (4.56 mg) compared to ointment (0.19 mg). A rabbit skin irritation study showed no sign of irritation after the application of cubosomal gel. In the radiant heat tail-flick study, the local anesthetic effect of lidocaine from the cubosomal gel was sustained for up to 16 h with 1.43-fold higher efficacy than marketed ointment. In conclusion, the study demonstrated the potential of cubosomal nanoparticle-laden gel to sustain the release of lidocaine for prolonging local anesthetic effects for pain management.

Lidocaine infusions in chronic pain management: A prospective case series analysis

Chronic pain conditions are prevalent and cause a significant burden of disease. Intravenous lidocaine infusions have been reported to have an analgesic effect in patients with chronic neuropathic pain, but there is limited data supporting the efficacy of lidocaine across other chronic pain phenotypes. Our study aimed to evaluate the efficacy of a single infusion of intravenous lidocaine for pain relief and the impact on quality of life. We evaluated data from 74 patients with chronic pain who were treated with intravenous lidocaine at a specialist pain centre. Participants completed a questionnaire consisting of the Brief Pain Inventory (BPI) Short Form and additional EQ-5D quality of life metrics, before treatment and at follow-up.

Data comparing pain severity did not demonstrate a statistically significant change after treatment when averaged across the entire patient cohort (6.15–5.88, p = .106), irrespective of gender or pain phenotype. Scores for pain interference showed statistically significant reductions following treatment (7.05–6.41, p = .023), which may have been driven through improvements in sleep (7.41–6.35, p = .001); however, these reductions are not clinically significant.

The patient cohort was stratified into responders and non-responders based on >30% improvement in response to an overall impression of pain reduction question following treatment. In the ‘responder’ cohort, pain intensity scores showed a statistically significant reduction post-infusion (6.18–5.49, p = .0135), but no change was apparent for non-responders (6.07–6.09, p = .920). There were no differences between responders and non-responders for pain sub-types in our study.

This study found no difference in pain outcomes in a cohort of patients with chronic pain, a mean of 63 days following a single lidocaine infusion. However, a specific subgroup of responders may show slight improvements in some pain outcomes that may warrant further exploration.

Lidocaine infusions and reduced opioid consumption-Retrospective experience in pediatric hematology and oncology patients with refractory pain

BACKGROUND

Despite a more robust experience with lidocaine infusions for pain management in adults and general pediatric population, there is limited evidence of efficacy of lidocaine infusions for pain management in patients with pediatric hematology and oncology diagnoses.

METHODS

Data pertaining to continuous intravenous lidocaine infusions prescribed between January 2009 and June 2019 were reviewed, including patients' demographic characteristics, hematology/oncology and pain diagnoses, concurrent pain medications, and lidocaine infusion dose regimens and duration. Pain scores and opioid consumption calculations based on morphine equivalent doses (mg/kg/day) of patient-controlled analgesia were collected 1 day before infusion (D1), during infusion (D2), and 1 day after infusion (D3).

RESULTS

The mean opioid consumption on D3 was significantly lower than that on D2 (p = .01). The pain scores on D3 were significantly lower than those on D1 when measured as average pain scores per 24 hours (p < .001) or as single pain scores immediately before and after infusions (p < .001). No significant associations were found between cumulative doses of lidocaine (loading dose plus total infusion dose) and either a decrease in the opioid consumption or a decrease in pain scores.

CONCLUSIONS

In this retrospective series of pediatric hematology and oncology cases, we report positive outcomes in reducing opioid consumption and pain scores after lidocaine infusions. Prospective investigations designed in a collaborative, multi-institutional fashion, including a variety of pediatric populations are needed to further investigate the efficacy of lidocaine infusions.

Lidocaine Infusions for Pain Management in Pediatrics

Lidocaine is an amino amide with a well-established role as a local anesthetic agent. Systemic intravenous administration expands its clinical use to include acute and chronic pain circumstances, such as postoperative pain, neuropathic pain, postherpetic neuralgia, hyperalgesia, visceral pain, and centrally mediated pain. For refractory pain that has not responded to conventional therapy or if further escalation of treatment is prevented by contraindications or side effects to standard therapies, a continuous infusion of lidocaine may be considered as a single intervention or as a sequence of infusions. Here, we review and evaluate published data reflecting the use of lidocaine continuous infusions for pain management in the pediatric population.

Intravenous lidocaine alleviates postherpetic neuralgia in rats via regulation of neuroinflammation of microglia and astrocytes

This study aimed to explore the effects and possible mechanisms of intravenous lidocaine in postherpetic neuralgia (PHN) rats. Mechanical withdrawal thresholds and thermal withdrawal latencies were measured. Open field test, elevated plus maze test, and tail suspension test were used to assess anxiety- and depressive-like behaviors. Microglia and astrocytes in spinal dorsal horn (SDH), prefrontal cortex (PFC), anterior cingulate cortex (ACC), and hippocampus were analyzed. The expression of TNF-α, IL-1β, and IL-4 in SDH and serum were evaluated. Intravenous lidocaine alleviated mechanical allodynia and thermal hypoalgesia, downregulated the expression of TNF-α and IL-1β, and inhibited the activation of microglia and astrocytes in SDH. In addition, it reduced the activation of astrocyte but not microglia in PFC, ACC, and hippocampus. Intravenous lidocaine may relieve PHN by inhibiting the activation of microglia and astrocyte in SDH or by reducing the neuroinflammation and astrocyte activation in PFC, ACC, and hippocampus.

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Intravenous lidocaine alleviates PHN in rats

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Intravenous lidocaine inhibits microglia and astrocyte activation

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Intravenous lidocaine cannot relieve anxiety and depression in PHN rats

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.

Lidocaine as an element of multimodal analgesic therapy in major spine surgical procedures in children: a prospective, randomized, double-blind study

Background

Introducing the principles of multimodal analgesic therapy is necessary to provide appropriate comfort for the patient after surgery. The main objective of the study was evaluating the influence of perioperative intravenous (i.v.) lidocaine infusion on postoperative morphine requirements during the first 48 h postoperatively in children undergoing major spine surgery.

Materials and methods

Prospective, randomized, double-blind study: 41 children, qualified to multilevel spine surgery, were randomly divided into two treatment groups: lidocaine and placebo (control). The lidocaine group received lidocaine as a bolus of 1.5 mg/kg over 30 minutes, followed by a continuous infusion at 1 mg/kg/h to 6 hours after surgery. The protocol of perioperative management was identical for all patients. Measurements: morphine demand, intensity of postoperative pain (the Numerical Rating Scale), oral feeding initiation time, first attempts at assuming erect position, postoperative quality of life (the Acute Short-form /SF-12/ health survey).

Results

Patient data did not differ demographically. Compared to the control group, lidocaine treatment reduced the demand for morphine during the first 24h [95% CI 0.13 (0.11-0.28) mg/kg, p = 0.0122], 48h [95% CI 0.46 (0.22-0.52) mg/kg, p = 0.0299] after surgery and entire hospitalization [95% CI 0.58 (0.19-0.78) mg/kg, p = 0.04]; postoperative pain intensity; nutritional withdrawal period [introduction of liquid diet (p = 0.024) and solid diet (p = 0.012)], and accelerated the adoption of an upright position [sitting (p = 0.048); walking (p = 0.049)]. The SF-12 generic health survey did not differ between groups before operation, 2 months and 4 years after surgery.

Conclusions

Perioperative lidocaine administration, as a part of the applied analgesic therapy regimen, may decrease postoperative opioid demand and accelerates convalescence of children undergoing major surgery.

Perioperative Intravenous Lidocaine Infusion Adverse Reaction: A Case Report

Intravenous lidocaine is increasingly being utilized as an opioid-sparing analgesic. A 55-year-old man with well-controlled human immunodeficiency virus on highly active antiretroviral therapy was prescribed a lidocaine infusion at 1 mg/kg/h for postoperative pain. On postoperative day 2, the patient experienced 4 unresponsive episodes with tachycardia, hypertension, and oxygen desaturation. Serum lidocaine level was available 2 days later (high 6.3 µg/mL, therapeutic range 2.5-3.5 µg/mL). There is significant pharmacokinetic interaction between lidocaine and this patient's human immunodeficiency virus medications. This case highlights the need for a readily accessible list of medications that caution against lidocaine. We propose in-house serum lidocaine levels to monitor patients at an increased risk for toxicity.

Intravenous infusion of lidocaine enhances the efficacy of conventional treatment of postherpetic neuralgia

BACKGROUND

Postherpetic neuralgia (PHN) is one kind of severe neuropathic pain which currently cannot be effectively cured. Recent researches suggest that intravenous infusion of lidocaine has a therapeutic effect on neuropathic pain such as PHN; however, the optimal dose and frequency of lidocaine infusion and the effectiveness and safety of this treatment in PHN patients still needs more clinical research. The aim of this study was to evaluate the therapeutic effects of daily intravenous lidocaine infusion on the outcome of the routine treatment of PHN.

METHODS

Sixty PHN patients were randomly divided into two groups: 1) control group (Control), treated with conventional therapies, such as antiepileptic pills, analgesics, neurotrophic medicines, paravertebral spinal nerve block and physiotherapy; 2) lidocaine group (Lido) received daily infusion of lidocaine (4 mg/kg) besides the conventional treatments. If the pain is not controlled sufficiently, additional tramadol is given and the average consumption of tramadol is calculated. Pain intensity was assessed before and after each infusion, and the number of breakthrough pain in the last 24 hrs were recorded. The incidence of adverse reactions related to intravenous lidocaine infusion was recorded.

RESULTS

For five consecutive days, numeric rating scale (NRS) scores were significantly decreased after 1 hr of intravenous infusion of lidocaine. Compared with Control, the NRS scores and the frequency of breakthrough pain in the Lido were significantly reduced. In addition, the extra tramadol consumption in the Lido was significantly lower than that in the Control, and the average hospital stay of patients in Lido was decreased. However, anxiety and depression scores showed no difference between Lido and Control.

CONCLUSION

Daily intravenous lidocaine (4 mg/kg for 5 days) enhanced the outcome of PHN treatment, reduced the amount of analgesic medicine and shortened the length of hospital stay with no obvious adverse side effects.

Targeting the Nav1.8 ion channel engenders sex-specific responses in lysophosphatidic acid-induced joint neuropathy

Joint neuropathic pain occurs in a subset of arthritis patients, and lysophosphatidic acid (LPA) has been implicated as a mediator of joint neuropathy. The mechanism by which LPA promotes neuropathic pain is unknown but may be related to altered signalling of the voltage-gated sodium channel Nav1.8 located on nociceptors. Because arthritis and neuropathic pain are more prevalent in females, this study aimed to explore potential sex differences in the development of LPA-induced joint neuropathy and whether Nav1.8 played a role in the associated neuropathic pain. Joint neuropathy was induced in male and female Wistar rats (179-284 g) by intra-articular injection of 50-µg LPA. Pain behaviour was assessed over 21 days using von Frey hair algesiometry. On day 21, electrophysiological recordings of joint primary afferents were conducted to measure peripheral sensitisation. Saphenous nerve morphology and expression of the nerve-damage marker ATF3 and Nav1.8 in ipsilateral dorsal root ganglions were compared on the basis of sex. The analgesic properties of the selective Nav1.8 antagonist A-803467 was determined in pain behaviour and electrophysiology experiments. Females developed more severe mechanical allodynia than males after LPA treatment. Lysophosphatidic acid caused more pronounced demyelination of the saphenous nerve in females, but no sex differences were observed in the expression of ATF3 or Nav1.8 in dorsal root ganglion neurones. Blockade of Nav1.8 channels with A-803467 resulted in a decrease in joint mechanosensitivity and secondary allodynia with females exhibiting a greater response. These findings suggest that LPA has sex-specific effects on joint neuropathy and Nav1.8 gating, which should be considered when treating neuropathic arthritis patients.

Efficacy of intravenous lidocaine in improving post-operative nausea, vomiting and early recovery after laparoscopic gynaecological surgery

Post-operative nausea and vomiting (PONV) is a major peri-operative complication. It has numerous adverse consequences that seriously affect the post-operative recovery of patients. The aim of the present study was to investigate the efficacy of intravenous lidocaine in improving PONV and recovery after laparoscopic gynaecological surgery. A total of 40 patients were randomly assigned to 2 groups: Group L (lidocaine group) and Group C (control group). The patients in Group L received intravenous lidocaine throughout the operation, while patients in Group C were given a saline infusion. Vital signs, recovery time, extubation time, dosage of remifentanil, first flatus time and defecation time of each patient were recorded. The incidence of PONV after surgery was also recorded. The recovery of the patients was evaluated by using the quality of recovery score (QoR-40). The total dose of remifentanil was significantly lower in Group L (P<0.05). However, the recovery time and extubation time were shorter in Group C (P<0.05). The first flatus time and defecation time were longer in Group C (P<0.05). The mean arterial pressure and heart rate in Group L were lower and more stable (P<0.05). At 6 h after surgery, the incidence of PONV was significantly lower in Group L vs. that in Group C (P<0.05). The QoR-40 score in Group C was significantly lower at 1 and 3 days after the operation compared with that in Group C (P<0.05). In conclusion, intravenous lidocaine administered to patients undergoing laparoscopic gynaecological surgery may reduce PONV and supports their early recovery [trial registration number in Chinese Clinical Trial Registry: ChiCTR-IOR-17010782 (March 5, 2017)].

Comparison of the Effect of Intra-Rectal Administration of Lidocaine Gel and Lidocaine Plus Fentanyl on Pain Reduction in Prostate Biopsy: A Randomized Clinical Trial

Objectives

The aim of this study was to compare the effect of intra-rectal administration of lidocaine gel alone versus lidocaine gel plus topical fentanyl on pain reduction in prostate biopsy.

Methods

In a double-blind randomized clinical trial, 96 patients who met the inclusion criteria were randomly assigned into two groups. 1) The treatment group: Lidocaine gel (2%) 50 g and 2) the intervention group: Lidocaine gel (2%) 50 g and fentanyl gel 50 µg. During the prostate biopsy, the VAS score was recorded. Blood pressure, heart rate, and patient level of consciousness were also analyzed.

Results

The mean VAS score was 5.1 ± 2 and 3.0 ± 2, which was lower in the intervention group (P value < 0.001). In terms of consciousness after biopsy, there was no difference between the two groups (P value = 0.358). There was no difference between the groups in terms of mean blood pressure and heart rate before and during the prostate biopsy. Finally, in terms of consciousness after the prostate biopsy, there was no difference between the current treatment and intervention groups.

Conclusions

The combination of lidocaine gel and fentanyl with a dose of 50 µg has a significant effect on reducing the pain associated with prostate biopsy in comparison with lidocaine gel alone. The antinociceptive effect of the above regimens is not associated with hemodynamic changes and changes in patients' consciousness.

Comparison of Efficacy Outcomes of Lidocaine Spray, Topical Lidocaine Injection, and Lidocaine General Anesthesia in Nasal Bone Fractures Surgeries: A Randomized, Controlled Trial

Background

Lidocaine is widely used as a general and local anesthetic in minor or major surgeries. The objective of the study was to compare postoperative pain relief and adverse events using different forms of lidocaine administration in patients following closed nasal bone reduction surgery.

Material/Methods

A total of 381 patients with a solitary nasal fracture that could be managed with closed reduction were included in this study and divided into 3 groups of 127 patients in each group. Patients had received 1% lidocaine HCl with epinephrine (LL group), inserted a mesh impregnated with lidocaine spray (TL group), or 1 mg/kg/h lidocaine infusion (GL group) before surgeries. Patients also received morphine when the pain was not controlled. The postoperative pain was assessed at 6 hours and 48 hours after surgery. Postoperative vomiting and nausea were evaluated. Repeated ANOVA/Tukey-Kramer multiple comparisons test was performed at 95% confidence level.

Results

At 6 hours after surgery, patients in the general lidocaine (GL) group reported decreased postoperative pain compared with those in the topical lidocaine (TL) group (P<0.001, q=6.633) and LL group (P<0.001, q=8.056). The morphine consumption within 48 hours was least in GL group than TL group (P<0.001, q=172.9) and LL group (P<0.001, q=226.42). Lidocaine infusion caused nausea (P<0.001, q=6.742) and vomiting (P<0.001, q=4.306).

Conclusions

Topical lidocaine anesthesia had the same postoperative pain relief and the least adverse events as local and general lidocaine anesthesia.

Effect of Perioperative Intravenous Lignocaine Infusion on Haemodynamic Responses and postoperative Analgesia in Laparoscopic Cholecystectomy Surgeries

BACKGROUND

During general anaesthesia, intubation of trachea and extubation of trachea are often associated with increase in haemodynamic response. Laparoscopic cholecystectomy is a minimal access surgery; postoperatively patients may experience moderate to severe pain. It is well known that lignocaine is useful in attenuating haemodynamic response to intubation and extubation. Previous studies also state that perioperative lignocaine infusion provides postoperative analgesia as well. We hypothesize that perioperative intravenous lignocaine infusion can both attenuate haemodynamic responses to intubation and extubation of trachea and also provide good postoperative analgesia in laparoscopic cholecystectomy surgeries.

METHODS

Double blinded randomized controlled trial was undertaken at the department of anesthesia, Sri Siddartha medical college. In group A, 0.9% normal saline was used as placebo for perioperative intravenous infusion. In group B, preservative free 1.5 mg/kg 2 % lignocaine (Loxicard) diluted with normal saline to 1% given at 10 minutes to induction as bolus, followed by an infusion of 1.5 mg/kg/h. till 1 hour postoperatively.

RESULTS

In Group B there was a statistically less rise in heart rate [HR] and mean blood pressure [MBP] during intubation and extubation of trachea compared to group A. In group B there was a statistically significant increase in the mean pain free period postoperatively compared to group A.

CONCLUSIONS

Perioperative intravenous infusion of lignocaine attenuates haemodynamic response during the intubation and extubation of the trachea. In addition, it also increases the mean pain free period postoperatively.