Postoperative analgesia by intra-articular neostigmine in patients undergoing knee arthroscopy

Intra-articular magnesium to alleviate postoperative pain after arthroscopic knee surgery: a meta-analysis of randomized controlled trials

Objective

We aimed to evaluate the safety and efficacy of intra-articular (IA) magnesium (Mg) for postoperative pain relief after arthroscopic knee surgery.

Methods

We searched PubMed, Embase, Medline, Cochrane library, and Web of Science to identify randomized controlled trials that compared postoperative pain outcomes with or without IA Mg after knee arthroscopy. The primary outcomes were pain intensity at rest and with movement at different postoperative time points and cumulative opioid consumption within 24 h after surgery. Secondary outcomes included the time to first analgesic request and side effects.

Results

In total, 11 studies involving 677 participants met the eligibility criteria. Pain scores at rest and with movement 2, 4, 12, and 24 h after surgery were significantly lower, doses of supplementary opioid consumption were smaller, and the time to first analgesic requirement was longer in the IA Mg group compared with the control group. No significant difference was detected regarding adverse reactions between the groups.

Conclusions

Intra-articular magnesium is an effective and safe coadjuvant treatment for relieving postoperative pain intensity after arthroscopic knee surgery.

Protocol registration at PROSPERO: CRD42020156403.

Molecular, Cellular and Circuit Basis of Cholinergic Modulation of Pain

In addition to being a key component of the autonomic nervous system, acetylcholine acts as a prominent neurotransmitter and neuromodulator upon release from key groups of cholinergic projection neurons and interneurons distributed across the central nervous system. It has been more than forty years since it was discovered that cholinergic transmission profoundly modifies the perception of pain. Directly activating cholinergic receptors or extending the action of endogenous acetylcholine via pharmacological blockade of acetylcholine esterase reduces pain in rodents as well as humans; conversely, inhibition of muscarinic cholinergic receptors induces nociceptive hypersensitivity. Here, we aim to review the considerable progress in our understanding of peripheral, spinal and brain contributions to cholinergic modulation of pain. We discuss the distribution of cholinergic neurons, muscarinic and nicotinic receptors over the central nervous system and the synaptic and circuit-level modulation by cholinergic signaling. AchRs profoundly regulate nociceptive transmission at the level of the spinal cord via pre- as well as postsynaptic mechanisms. Moreover, we attempt to provide an overview of how some of the salient regions in the pain network spanning the brain, such as the primary somatosensory cortex, insular cortex, anterior cingulate cortex, the medial prefrontal cortex and descending modulatory systems are influenced by cholinergic modulation. Finally, we critically discuss the clinical relevance of cholinergic signaling to pain therapy. Cholinergic mechanisms contribute to several both conventional as well as unorthodox forms of pain treatments, and reciprocal interactions between cholinergic and opioidergic modulation impact on the function and efficacy of both opioids and cholinomimetic drugs.

Is intra-articular magnesium effective for postoperative analgesia in arthroscopic shoulder surgery?

As an N-methyl-D-aspartate receptor antagonist, magnesium has been hypothesized to have analgesic effects; in fact, several studies have demonstrated its efficacy for analgesia following intra-articular injection during knee surgery. In this study, intra-articular magnesium was administered during arthroscopic shoulder surgery and its analgesic efficacy was assessed according to pain intensity after surgery as well as postoperative consumption of pain medications.

BACKGROUND:

Various medications are used intra-articularly for postoperative pain reduction after arthroscopic shoulder surgery. Magnesium, a N-methyl-D-aspartate receptor antagonist, may be effective for reduction of both postoperative pain scores and analgesic requirements.

METHODS:

A total of 67 patients undergoing arthroscopic shoulder surgery were divided randomly into two groups to receive intra-articular injections of either 10 mL magnesium sulphate (100 mg/mL; group M, n=34) or 10 mL of normal saline (group C, n=33). The analgesic effect was estimated using a visual analogue scale 1 h, 2 h, 6 h, 8 h, 12 h, 18 h and 24 h after operation. Postoperative analgesia was maintained by intra-articular morphine (0.01%, 10 mg) + bupivacaine (0.5%, 100 mL) patient-controlled analgesia device as a 1 mL infusion with a 1 mL bolus dose and 15 min lock-out time; for visual analogue scale scores >5, intramuscular diclofenac sodium 75 mg was administered as needed during the study period (maximum two times).

RESULTS:

Intra-articular magnesium resulted in a significant reduction in pain scores in group M compared with group C 1 h, 2 h, 6 h, 8 h and 12 h after the end of surgery, respectively, at rest and with passive motion. Total diclofenac consumption and intra-articular morphine + bupivacaine consumption were significantly lower in group M. Postoperative serum magnesium levels were significantly higher in group M, but were within the normal range.

CONCLUSIONS:

Magnesium causes a reduction in postoperative pain in comparison to saline when administered intra-articularly after arthroscopic shoulder surgery, and has no serious side effects.

Non-narcotic adjuvants may improve the duration and quality of analgesia after knee arthroscopy: a brief review

PURPOSE

We have evaluated randomized controlled trials of the administration of clonidine, neostigmine, steroids and non-steroidal anti-inflammatory agents intra-articularly as adjuvants to local anesthetic drugs after arthroscopic knee surgery.

METHODS

Twenty-five studies were reviewed using specific inclusion criteria and, accordingly, included in the final assessment. These studies were assessed for pain scores, total analgesic consumption and time to first analgesic request to determine a possible peripheral effect, as opposed to possible systemic effects of an adjuvant administered intra-articularly.

RESULTS

A total of 16 studies, met the inclusion criteria. These studies considered the use of non-steroidal anti-inflammatory drugs, steroids, neostigmine and clonidine. Ketorolac was used in four studies (for a total of 230 patients) and showed a significant improvement in analgesia. Clonidine has shown considerable analgesic effect, with minimal adverse effects. All seven studies assessed in this review were supportive (a total of 424 patients). Furthermore the addition of clonidine to bupivacaine or morphine was found to increase duration and quality of postoperative analgesia.

CONCLUSIONS

Current evidence indicates that a variety of agents have synergistic effects when added to local anesthetics and there is evidence that the improvement in analgesia is, at least partially, through a local rather than a central mechanism. The results of this review suggest that clonidine and ketorolac, when administered intra-articulary after arthroscopic knee surgery, may reduce postoperative pain.

Pain relief following Arthroscopy - a comparative study of Intra-articular Bupivacaine, Morphine and Neostigmine

Pain after arthroscopy is quite distressing. Intra-articular bupivacaine produces transient analgesia and reports of analgesia using intra-articular opioids have produced conflicting results. Recently, spinal administration of neostigmine was shown to produce dose-dependant analgesia. However, this was limited by adverse effects. The purpose of this study was to compare the effects on intra-articular neostigmine, bupivacaine and morphine. 75 patients were randomized to receive intra-articular saline, bupivacaine, morphine, neostigmine and bupivacaine-neostigmine after arthroscopic surgery under spinal anaesthesia. Visual analog pain scores (VAS), duration of analgesia as defined as time for first demand for parenteral opioids and the total subsequent consumption of morphine was evaluated. Intra-articular bupivacaine resulted in significant VAS reduction at one and four hours as compared to those receiving intra-articular saline and morphine. Analgesia lasted longer after 500ugm intra-articular neostigmine as compared with bupivacaine, morphine or saline. The need for supplementary analgesia was lowest in the neostigmine group as compared to the other groups. No significant difference was found if bupivacaine was added to neostigmine. Among all the groups, no significant side-effects were observed.

Intravenous regional anesthesia using lidocaine and neostigmine for upper limb surgery

STUDY OBJECTIVE

To evaluate the effect of adding neostigmine to lidocaine in intravenous regional anesthesia (IVRA).

DESIGN

Randomized, double-blinded study.

SETTING

Tertiary-care academic medical institution.

PATIENTS

40 ASA physical status I and II patients scheduled for elective or emergency forearm and hand surgery.

INTERVENTION

Patients were randomized to two groups of 20 patients each. In the control group, IVRA was established using 40 mL of 0.5% lidocaine with one mL of isotonic saline, while neostigmine group patients received 40 mL of 0.5% lidocaine with 0.5 mg neostigmine.

MEASUREMENTS

Hemodynamic parameters, onset and recovery times of sensory and motor blocks, and quality of anesthesia achieved with IVRA were recorded. After tourniquet deflation, visual analog pain scores (VAS) were noted every 30 minutes in the first two hours, as were the time to first analgesic request and total analgesic requirement in the 24-hour postoperative period.

MAIN RESULTS

In the first 24 hours after surgery, the neostigmine group had significantly lower VAS scores, longer time to first analgesic request, and reduced total analgesic requirement. Intraoperatively, the neostigmine group had significantly shorter sensory and motor block onset times and longer recovery times than the control group. No significant frequency of adverse effects was seen in either group. The quality of intraoperative anesthesia and frequency of tourniquet pain were similar in both groups.

CONCLUSIONS

The addition of neostigmine to lidocaine shortens onset time and improves postoperative analgesia in IVRA for upper limb surgery.

Intra-articular sufentanil in multimodal analgesic management after outpatient arthroscopic anterior cruciate ligament reconstruction: a prospective, randomized, double-blinded study

PURPOSE

This prospective, randomized, blinded study was designed to evaluate the effectiveness of intra-articular sufentanil, ropivacaine, and clonidine compared with that of ropivacaine and clonidine without sufentanil on postoperative pain after arthroscopic reconstruction of the anterior cruciate ligament of the knee.

METHODS

One hundred twenty patients were enrolled and randomly divided into 2 groups. At the end of the operation, the surgeon injected 20 mL of a solution containing 5 microg sufentanil, 100 mg ropivacaine, and 1 microg/kg clonidine in the knees of patients in group A whereas the surgeon injected the same solution without sufentanil in group B. During the postoperative period and for the first 24 hours, we recorded pain intensity using a visual analog scale.

RESULTS

All patients were discharged after a few hours with well-controlled pain. Pain scores were low in both groups both before and after discharge. We did not show any difference in pain scores at any time point. During the first postoperative hour, patients in group B required more rescue analgesic drugs (P < .05).

CONCLUSIONS

In our patients the addition of sufentanil in the intra-articular solution did not provide better control of pain.

LEVEL OF EVIDENCE

Level I, therapeutic randomized controlled trial.

Clinically useful adjuvants in regional anaesthesia

PURPOSE OF REVIEW

In this review, emphasis is placed on adjuvant drugs that are already in clinical use. The list of adjuvants studied during the review period includes adrenaline, clonidine, ketamine, neostigmine, nondepolarizing muscle relaxants, and nonsteroidal antiinflammatory drugs. Some future aspects are considered in a couple of experimental studies on slow-release local anaesthetic formulations.

RECENT FINDINGS

Adrenaline not only acts as a vasoconstrictor, it may also produce analgesia through an alpha2-adrenergic mechanism. Adrenaline may facilitate the uptake of the local anaesthetic into nerves. The addition of adrenaline to a mixture of ropivacaine and fentanyl clearly improves thoracic epidural analgesia. Several recent studies have shown a synergism of clonidine with local anaesthetics in various types of blocks, as well as with spinal opioids. Bradycardia and hypotension may be associated with the use of clonidine. Neostigmine may cause antinociception both in the spinal cord and in peripheral nerves. Neostigmine has been found to potentiate the effect of spinal opioids, but gastrointestinal side effects are frequent. Biodegradable microcapsules containing bupivacaine and dexamethasone have been tested in humans and found to produce analgesia for several days (intercostal block). Local inflammatory reactions and paraesthesias, however, were observed in 30% of cases.

SUMMARY

Adrenaline and opioids may be regarded as the best investigated and most important adjuvants in regional anaesthesia. Other drugs, such as clonidine and neostigmine, may prolong analgesia in various regional anaesthetic techniques, but possible side effects may limit their clinical application. Further development is needed concerning extra-long acting analgesic formulations.

Useful adjuvants for postoperative pain management

Adjuvants are compounds which by themselves have undesirable side-effects or low potency but in combination with opioids allow a reduction of narcotic dosing for postoperative pain control. Adjuvants are needed for postoperative pain management due to side-effects of opioid analgesics, which hinder recovery, especially in the increasingly utilized ambulatory surgical procedures. NMDA antagonists have psychomimetic side-effects at high doses, but at moderate doses do not cause stereotypic behavior but allow reduction in opioid dose to obtain better pain control. Alpha-2 adrenergic agonists cause sedation, hypotension and bradycardia at moderate doses, but at low doses can be opioid sparing especially in spinal administration. Gabapentin-like compounds have low potency against acute pain, but in combination with opioids allow a reduction in opioid dose with improved analgesia. Corticosteroids may have only a limited role as adjuvants while acetylcholine esterase inhibitors may have too many side-effects. Newer adjuvants will be needed to reduce opioid dose and concomitant side-effects, even more as same day surgeries become more routine.

Perioperative pain management

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

Use of neostigmine in the management of acute postoperative pain and labour pain: a review

Neostigmine is a parasympathomimetic agent that has been recently investigated for use as an adjunct analgesic agent in the perioperative and peripartum period. A number of studies have investigated the intrathecal, epidural, caudal and intra-articular routes of administration of this agent, as well as the addition of neostigmine to local anaesthetics used for brachial plexus block and intravenous regional anaesthesia. While the intrathecal administration of neostigmine produced useful analgesic effects in the postoperative period in some studies, the high incidence of adverse events, mainly nausea and vomiting, limit the clinical usefulness of this route of administration. Several studies investigated the postoperative analgesic effects of epidural neostigmine using a number of different regimens. Overall, this route of administration appeared to improve postoperative analgesia in most studies without increasing the incidence of adverse events, and merits further research. Neuraxial administration of neostigmine appears to be safe in the obstetric population, with no reported adverse effects in the mother or fetus. While intrathecal administration is limited by a high incidence of nausea and vomiting in this patient population, the epidural route appears more promising and requires further investigation. The addition of neostigmine to caudal local anaesthetics was associated with improved postoperative analgesia in a number of studies. A dose of 2 microg/kg proved to be effective in several studies but was associated with an increased incidence of vomiting in some studies. Intra-articular administration of neostigmine 500microg produced a useful analgesic effect in the postoperative period in several studies and was not associated with an increase in the incidence of adverse effects. Studies investigating the efficacy of adding neostigmine to the local anaesthetics used for brachial plexus block and intravenous regional anaesthesia reported conflicting results. Further studies are required to determine the place of the administration of neostigmine by these routes.

Intraarticular analgesia after arthroscopic knee surgery: comparison of neostigmine, clonidine, tenoxicam, morphine and bupivacaine

We conducted a randomized, placebo-controlled, double blinded study to compare the analgesic effects of intraarticular neostigmine, morphine, tenoxicam, clonidine and bupivacaine in 150 patients undergoing arthroscopic knee surgery. General anaesthesia protocol was same in all patients. At the end of the surgical procedure, patients were randomized into six intraarticular groups equally. Group N received 500 mug neostigmine, Group M received 2 mg morphine, Group T received 20 mg tenoxicam, Group C received 1 microg kg(-1) clonidine, Group B received 100 mg bupivacaine and Group S received saline 20 ml. Visual analog scale scores 0, 30 and 60 min and 2, 4, 6, 12, 24, 48 and 72 h, time to first analgesic need, analgesic consumption at 48 h and 72 h and side effects were noted. Demographic and operational parameters were similar in six groups. All study groups provided analgesia when compared with saline group (P<0.05). Duration of analgesia in Group N and C was longer than other groups (P<0.001). Analgesic consumptions of Group N, C and T were lower than other groups (P<0.01). Pain scores during 2 h postoperatively were lower in all study groups than the control group (P<0.001). In Group B, median pain scores were higher than Groups N and C at 0 min and 30 min postoperatively (P<0.001). Side effects were not significantly different among the six groups. We conclude that the most effective drugs that are administered intraarticularly are neostigmine and clonidine among the five drugs we studied. Tenoxicam provided longer analgesia when compared with morphine and bupivacaine, postoperatively.

Bupivacaine/ketamine is superior to intra-articu-lar ketamine analgesia following arthroscopic knee surgery

PURPOSE

Centroneuraxial and parenteral administration of ketamine has been shown to produce analgesia. However, this analgesia is limited by adverse effects. The purpose of this study was to determine whether ketamine alone or in combination with bupivacaine provides superior pain relief after surgery in patients undergoing knee arthroscopy.

METHODS

Sixty patients (classified as ASA status I or II) under-going arthroscopic meniscus repair during general anesthesia were randomized to receive 1.0 mg x kg(-1) ketamine (Group K), 0.25% bupivacaine (Group B) or a combination of 1.0 mg x kg(-1) ketamine and 0.25% bupivacaine (Group BK) to a total volume of 20 mL by intra-articular route following surgery. Visual analogue score in the postanesthesia care unit at 0.5, 1, 2, 4, 6, 8, 12 and 24 hr after surgery, duration of analgesia and subsequent 24 hr consumption of rescue analgesic (dextroproxyphene/acetaminophen) were evaluated.

RESULTS

The results showed significantly higher pain scores in Group K as compared to Group B and Group BK. The duration of analgesia was significantly shorter in Group K as compared to the other two groups (Group B = 5.7 +/- 0.8; Group BK = 5.1 +/- 1.1 vs Group K = 1.7 +/- 0.9 hr; P < 0.05). However, 24 hr consumption of analgesic was similar in the three groups.

CONCLUSION

We conclude that intra-articular bupivacaine-ketamine combination provides better pain relief than intra-articular ketamine after day care arthroscopic knee surgery.

Comparisons of analgesic effects of different doses of morphine and morphine plus methylprednisolone after knee surgery

BACKGROUND

In this double-blind randomized study, the analgesic effects of morphine alone and with methylprednisolone were examined in 72 patients undergoing arthroscopic knee surgery.

METHODS

At the end of arthroscopy, patients were allocated randomly to one of four groups to receive intra-articular administrations of saline, morphine 1 mg, morphine 5 mg or morphine 1 mg with methylprednisolone 40 mg. Preoperative and postoperative pain levels at rest and during movement (active flexion of the knee) were measured by a visual analogue scale (VAS). Postoperative analgesic requirements to alleviate pain were evaluated.

RESULTS

Pain scores were significantly lower for the patients who received 5 mg morphine and 1 mg morphine with 40 mg methylprednisolone than for those who received saline or 1 mg morphine. This was accompanied by a decrease in the postoperative consumption of analgesics and prolongation of the duration of pain relief.

CONCLUSIONS

This study confirms that the analgesic effect of morphine given intra-articularly is dose dependent and that combination of methylprednisolone with morphine has an additive effect on analgesia.

The effects of ketorolac and morphine on articular cartilage and synovium in the rabbit knee joint

Analgesics are commonly injected intra-articularly for analgesia after arthroscopic surgery, especially of knee joints. The aim of this study was to research the effects of ketorolac and morphine on articular cartilage and synovial membrane. This study used rabbit right and left hind knee joints. The treatments, saline, morphine, or ketorolac, were administered intra-articularly 24 h after injection, and 5 joints from animals in each drug group were chosen randomly to form Group I and subgroups of Group I. The same procedures were applied after 48 h and 10 days of injection to form Groups II and III, respectively, and subgroups of these groups. Knee joints were excised and a blinded observer evaluated the histopathology according to inflammation of the articular cartilage, inflammatory cell infiltration, hypertrophy, and hyperplasia of the synovial membrane. No histopathological changes were found in the control groups. In the ketorolac and morphine groups, there were varying degrees of synovial membrane inflammatory cell infiltration and minimal, mild, or moderate synovial membrane cell hyperplasia or hypertrophy. Except for the ketorolac group at 24 h, both ketorolac and morphine groups showed more histopathological changes than controls (p < 0.05). Morphine and ketorolac both cause mild histopathological changes in rabbit knee joints, morphine causing more than ketorolac, but both of the drugs can be used intra-articularly with safety.

Role of Analgesic Adjuncts in Postoperative Pain Management

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

Impact of Acute Pain and Its Management for Thoracic Surgical Patients

Perioperative analgesia for thoracotomy has evolved in concert with increasing knowledge of the impact of pain on recovery, the origin of this pain, and new methods for treating it. Thoracic surgery is one of the few areas where there is more general agreement between surgeons and anesthesiologists as to the importance of aggressive pain management, often with an indwelling epidural catheter left in place until after thoracostomy tube removal. The reasons for this agreement is that it has become increasingly clear to both specialties that pain puts patients with decreased pulmonary reserve who undergo thoracotomy at greater risk for morbidity. Future studies need to examine drugs or drug combinations that can lead to further reductions in the often intense pain that patients receiving aggressive epidural analgesia still experience. Studies directed at finding interventions capable of reducing the rate of long-term postthoracotomy pain still need to be performed.

The Effects of Bupivacaine and Neostigmine on Articular Cartilage and Synovium in the Rabbit Knee Joint

We investigated the effects of intraarticular injections of bupivacaine and neostigmine on articular cartilage and the synovial membrane of rabbit knee joints. Saline, bupivacaine or neostigmine were each administered intra-articularly into 15 knee joints. Five joints per drug treatment were prepared for histopathological examination 24 h, 48 h and 10 days after injection. A pathologist examined the histological samples for inflammation of the articular cartilage, inflammatory cell infiltration, hypertrophy and hyperplasia of the synovial membrane, in a blinded manner. There were no histopathological changes in the saline-treated control joints. Joints treated with bupivacaine and neostigmine showed significantly more histopathological changes than control joints. Joints treated with neostigmine showed significantly more histopathological changes than those treated with bupivacaine, except for articular cartilage inflammation on day 10. We conclude that intra-articular bupivacaine and neostigmine cause histopathological changes in rabbit knee joints, with neostigmine having a greater effect than bupivacaine.

The efficacy of intra-articular ketamine for postoperative analgesia in outpatient arthroscopic surgery

PURPOSE

The purpose of this study was to compare the postoperative analgesic effects of intra-articularly administered ketamine, neostigmine, and bupivacaine after outpatient arthroscopic surgery.

TYPE OF STUDY

Prospective, randomized, double-blind, clinical study.

METHODS

In this study, 60 patients undergoing arthroscopic surgery other than ligament reconstruction were evaluated for postoperative pain. Ketamine, neostigmine, and bupivacaine were administered intra-articularly. The period of effective analgesia, recorded in minutes, was measured between time 0 and first usage of patient-controlled anesthesia (PCA) by the patients. The visual analog scale (VAS) was used to describe the pain level of the patient.

RESULTS

VAS values were lower for the 3 medication groups compared with the placebo at rest and 90 degrees knee flexion. Intra-articular administration of 0.5 mg/kg ketamine provided longer duration of analgesia as defined by the first PCA use time (P <.05). The total amount of pethidine and analgesia time were longer for the 3 medication groups.

CONCLUSIONS

Our basic finding was reduction in postoperative pain and consumption of adequate analgesic drugs with intra-articular ketamine, bupivacaine, or neostigmine use. We have not seen any psychomimetic side effects, particularly as seen with higher doses or systemic use. This study may conclude that intra-articular administration of ketamine provides long-lasting and effective analgesia, similar to neostigmine but less effective than bupivacaine after knee arthroscopy without any adverse effects. LEVEL OF EVEIDENCE: Level I.

Effective pain relief from intra-articular saline with or without morphine 2 mg in patients with moderate-to-severe pain after knee arthroscopy: a randomized, double-blind controlled clinical study

BACKGROUND

Intra-articular (IA) morphine has given good and prolonged pain relief in some studies when given at the end of arthroscopic procedures in the knee joint. However, similar studies have not been able to document any local analgesic effect of morphine. A large number of the negative studies have not demonstrated any assay sensitivity. We have documented that around 40% of patients have only very mild or no pain after arthroscopic procedures in the knee joint. This obviously is a confounding factor, reducing assay sensitivity when all patients are included in IA morphine studies.

METHOD

By leaving a soft catheter IA in 57 patients and including only patients who developed moderate-to-severe pain within 1 h after an arthroscopic procedure in the knee joint under general anaesthesia, we included 40 patients. These patients had a mean pre-treatment baseline pain of about 50/100 on a 100-mm visual analogue scale (VAS) for pain intensity. A randomized, double-blind controlled comparison of saline 10 ml with or without morphine 2 mg followed. Test drugs were administered through the IA catheter. Pain intensity and pain relief, consumption of rescue analgesics and global evaluation of effect and adverse effects were measured up to 36 h thereafter.

RESULTS

Pain intensity decreased from about 50 to about 10-15/100 in both groups and the sum of pain intensity differences at 2 and 22 h was not significantly different between the two groups. Global evaluation of effects and adverse effects, as well as consumption of rescue analgesics during 36 h after arthroscopic procedures, were also similar in the two groups.

CONCLUSIONS

Only 70% of 57 patients had pain of moderate-to-severe intensity within 1 h after an arthroscopic procedure of the knee joint under general anaesthesia. IA injection of saline 10 ml and saline 10 ml with morphine 2 mg were both associated with pain relief. These findings may have implications for interpretations of a majority of published studies on IA morphine.

[Neostigmine added to bupivacaine in axillary plexus block: which benefit?]

INTRODUCTION

Recent study showed that neostigmine (500 microg) by intra-articular produces postoperative analgesia without adverse effect. The author's goal was to determine whether 500 microg of neostigmine added to bupivacaine in axillary plexus block could prolonged postoperative analgesia without increasing the incidence of side effects.

METHODS

Ninety patients scheduled for orthopedic or plastic surgery with axillary plexus block were randomly assigned to one of 3 groups : group 1 (TGr n = 30) received saline solution (1 ml) in the axillary plexus, group 2 (NAGr n = 30) received 500 microg (1 ml) neostigmine in the axillary plexus and group 3.500 microg neostigmine subcutaneously (NSGr n = 30). We evaluated visual analog pain scores (VAS), the consumption of the ketoprofene, nausea and vomiting incidence during the first 24 h. ANOVA, Kruskall Wallis and Fisher tests were used for statistical analysis. A p value of <0.05 was considered significant.

RESULTS

The VAS score was lower in NAGr (21 +/- 18) vs NSGr (31 +/- 14) and control group TGr (45 +/- 2) (p < 0.05). The consumption of the ketoprofene is 127 +/- 65 mg in NAGr vs 150 +/- 53 mg in NSGr and 200 +/- 50 mg in group TGr (p = 0.02). Incidence of nausea and vomiting was 3.5% in NAGr vs 6.8% in NSGr and 0% for TGr.

CONCLUSION

Neostigmine combined to a mixture of lidocaine and bupivacaine prolongs postoperative analgesia after axillary plexus block.

Topical and peripherally acting analgesics

Acute nociceptive, inflammatory, and neuropathic pain all depend to some degree on the peripheral activation of primary sensory afferent neurons. The localized peripheral administration of drugs, such as by topical application, can potentially optimize drug concentrations at the site of origin of the pain, while leading to lower systemic levels and fewer adverse systemic effects, fewer drug interactions, and no need to titrate doses into a therapeutic range compared with systemic administration. Primary sensory afferent neurons can be activated by a range of inflammatory mediators such as prostanoids, bradykinin, ATP, histamine, and serotonin, and inhibiting their actions represents a strategy for the development of analgesics. Peripheral nerve endings also express a variety of inhibitory neuroreceptors such as opioid, alpha-adrenergic, cholinergic, adenosine and cannabinoid receptors, and agonists for these receptors also represent viable targets for drug development. At present, topical and other forms of peripheral administration of nonsteroidal anti-inflammatory drugs, opioids, capsaicin, local anesthetics, and alpha-adrenoceptor agonists are being used in a variety of clinical states. There also are some clinical data on the use of topical antidepressants and glutamate receptor antagonists. There are preclinical data supporting the potential for development of local formulations of adenosine agonists, cannabinoid agonists, cholinergic ligands, cytokine antagonists, bradykinin antagonists, ATP antagonists, biogenic amine antagonists, neuropeptide antagonists, and agents that alter the availability of nerve growth factor. Given that activation of sensory neurons involves multiple mediators, combinations of agents targeting different mechanisms may be particularly useful. Topical analgesics represent a promising area for future drug development.

Caudal neostigmine, bupivacaine, and their combination for postoperative pain management after hypospadias surgery in children

In a randomized, double-blinded study, we examined the analgesic efficacy of caudal neostigmine, bupivacaine, or a mixture of both drugs in 60 children. After the induction of general anesthesia, children were allocated randomly into three groups (n = 20) to receive a caudal injection of either 0.25% bupivacaine 1 mL/kg, with or without neostigmine 2 micro g/kg, or neostigmine 2 micro g/kg in normal saline 1 mL/kg. Intraoperatively, children receiving caudal bupivacaine or a bupivacaine/neostigmine mixture maintained hemodynamic stability, required less inhaled anesthetics, and had a shorter recovery time compared with the caudal neostigmine alone. Postoperatively, the caudal bupivacaine/neostigmine mixture resulted in superior analgesia compared with the other two groups. Recovery to first rescue analgesic times were (mean +/- SD) 22.8 +/- 2.9 h, 8.1 +/- 5.9 h, and 5.2 +/- 2.1 h in the bupivacaine/neostigmine, bupivacaine, and neostigmine groups, respectively (P < 0.001). In addition, the bupivacaine and neostigmine groups received more doses of paracetamol than the bupivacaine/neostigmine group to maintain adequate analgesia in the first 24 postoperative h. Postoperative vomiting occurred in 25%, 10%, and 30% in the caudal bupivacaine/neostigmine, bupivacaine, and neostigmine groups, respectively (P < 0.01). We conclude that caudal neostigmine 2 micro g/kg provides postoperative analgesia comparable to caudal bupivacaine in children undergoing hypospadias repair surgery.

IMPLICATIONS

Caudal neostigmine 2 micro g/kg provides postoperative analgesia comparable to caudal bupivacaine in children undergoing hypospadias repair surgery. Co-administration of the two drugs is associated with extended postoperative analgesia and reduced need for supplementary analgesics.

Intravenous regional anesthesia using prilocaine and neostigmine

Neostigmine has been added to local anesthetics for central and peripheral nerve blocks resulting in prolonged, increased anesthesia and improved analgesia. We conducted this study to evaluate the effects of neostigmine when added to prilocaine for IV regional anesthesia (IVRA). Thirty patients undergoing hand surgery were randomly assigned to two groups to receive IVRA. The control group received 1 mL of saline plus 3 mg/kg of prilocaine diluted with saline to a total dose of 40 mL; the study group received 0.5 mg of neostigmine plus 3 mg/kg of prilocaine diluted with saline to a total dose of 40 mL. Sensory and motor block onset and recovery, anesthesia quality determined by an anesthesiologist, anesthesia quality determined by a surgeon, and dryness of the operative field were noted. Heart rate, mean arterial blood pressure, and oxygen saturation values were noted at 1, 5, 10, 20, and 40 min before surgery and after tourniquet release. Time to first analgesic requirement was also noted. Shortened sensory and motor block onset times, prolonged sensory and motor block recovery times, improved quality of anesthesia, and prolonged time to first analgesic requirement were found in the neostigmine group. We conclude that neostigmine as an adjunct to prilocaine improves quality of anesthesia and is beneficial in IVRA.

IMPLICATIONS

Neostigmine has been added to local anesthetics for central and peripheral nerve blocks. This study was conducted to evaluate the effects of neostigmine when added to prilocaine for IV regional anesthesia (IVRA). Neostigmine as an adjunct to prilocaine improves quality of anesthesia and is beneficial in IVRA.

Current treatment options for acute pain

The pain that accompanies surgical procedures remains prevalent and is an aspect of the perioperative experience that generates the greatest concern for patients about to undergo surgery. There is also a growing recognition of the extent that acute painful experiences can lead to longer-term painful consequences, even when tissue healing appears to be complete. The neurobiologic basis of this has been partially elucidated. The key observations are that multiple sites and multiple receptors collectively contribute, and that noxious stimuli initiate a cascade of events that sensitise the nervous system so that subsequent noxious stimuli are perceived with greater intensity and even previously non-painful stimuli can be painful. Incorporating these observations into effective perioperative regimens designed to limit acute pain and its consequences leads to a multimodal pre-emptive approach to acute pain management. Acute perioperative pain is an ideal setting for the use of pre-emptive analgesic techniques because the timing of noxious stimuli is known in advance and surgical sensitisation of the nervous system is ongoing despite adequate levels of general anaesthesia with volatile anaesthetics. The relevant neurobiology of pain, reviewed in this article, is the basis for advocating an aggressive, multimodal, pre-emptive approach to acute pain therapy throughout the entire perioperative period. A growing body of outcome studies demonstrates the long-term efficacy of this approach.

No pain, no gain: clinical excellence and scientific rigour--lessons learned from IA morphine

The effectiveness of intra-articular (IA) morphine in arthroscopic procedures of the knee joint was analysed in all randomised and controlled trials that included injections of morphine and placebo into the knee joint, and where the data were analysable. Sensitivity of the studies and effectiveness were analysed for three different periods: immediate (0-2h), early (2-6h) and late (6-30h). Sensitivity for each period was assumed if pain intensity was at least 30% of the maximum of 100 on the visual analogue scale in the placebo group. Six different doses (1-10mg) of IA morphine were compared with placebo. The injections were made at the end of surgery, before the arthroscope was removed from the joint. In the immediate period 7/15 sensitive trials were positive, in the early period 8/12 sensitive trials were positive and in the late period 10/13 sensitive trials were positive. Most positive studies had used higher doses (3-5mg) compared with negative studies that had mainly used 1mg. Two studies using patient controlled analgesia consumption of analgesics as an outcome were also positive. The only sensitive study of four dose-response comparisons indicated that 5mg of IA morphine was more effective than 1mg. The only sensitive study of three cross-route comparisons showed no difference between 5mg of IA and 5mg of intra-muscular morphine. All insensitive trials, including placebo (except two individual comparisons), cross-route and dose-response comparisons, were negative. The analysis of sensitive studies indicates that 5mg of IA morphine injected into the knee joint provides postoperative pain relief for up to 24h. A minimum of 30% of the maximum possible pain intensity is needed for an analgesic effect to be detected in a study.

Incisional and intra-articular infusions

Incisional and intra-articular local anaesthetic techniques are simple, safe and inexpensive analgesic methods for the management of post-operative pain following a variety of surgical procedures. These techniques are capable of providing effective analgesia over a limited field and with minimal systemic effects. In the literature single-dose local anaesthetics have been administered in most of the studies; however, the duration of analgesia is short-lived. In recent years catheter techniques have been increasingly used as intermittent bolus or continuous infusion in the surgical wound or intra-articularly for long-lasting post-operative analgesia in both hospitalized and day-case patients. The incisional and intra-articular use of opioids and several non-opioids, either alone or in combination with local anaesthetics, has also been evaluated. This chapter reviews the current status of single dose and infusions of local anaesthetics and adjuvants for incisional and intra-articular analgesic techniques and also looks at future perspectives.

Drug interactions with patient-controlled analgesia

Patient-controlled analgesia (PCA) has become standard procedure in the clinical treatment of pain. Its widespread use in patients with all kinds of diseases opens a variety of possible interactions between analgesics used for PCA and other drugs that might be administered concomitantly to the patient. Many of these drug interactions are of little clinical importance. However, some drug interactions have been reported to result in serious clinical problems. Drug interactions can either predominantly affect the pharmacokinetics or pharmacodynamics of the drug. Most important pharmacokinetic drug interactions occur at the level of drug metabolism or protein binding. Acceleration of methadone metabolism caused by cytochrome P450 (CYP) 3A4 induction by antiretroviral drugs or rifampicin (rifampin) has caused methadone withdrawal symptoms. Lack of morphine formation from codeine as a result of CYP2D6 inhibition by quinidine results in an almost complete loss of the analgesic effects of codeine. Alterations of methadone protein binding caused by an inhibition of alpha1-acid glycoprotein synthesis by alkylating substances are another possibility for predominantly pharmacokinetically based drug interactions during PCA. Furthermore, inhibition of P-glycoprotein by anticancer drugs could result in altered transmembrane transport of morphine, methadone or fentanyl, although this has not been shown to be of clinical relevance. Synergistic effects of systemically administered opioids with spinally or topically delivered opioids or anaesthetics have been reported frequently. The same is true for the opioid-sparing effects of coadministered non-opioid analgesics. Antidepressants, anticonvulsants or alpha2-adrenoreceptor agonists have also been shown to exert additive analgesic effects when administered together with an opioid. Inconsistent findings, however, are reported regarding the treatment of patients with opioid-induced nausea and sedation, since coadministration of antiemetics either increased or decreased the respective adverse effects or revealed additional unwanted drug effects.

Neostigmine interactions with non steroidal anti-inflammatory drugs

1. The common mechanism of action of non-steroidal anti-inflammatory drugs (NSAIDs) is the inhibition of the enzyme cyclo-oxygenase (COX), however, this inhibition is not enough to completely account for the efficacy of these agents in several models of acute pain. 2. It has been demonstrated that cholinergic agents can induce antinociception, but the nature of the interaction between these agents and NSAIDs drugs has not been studied. The present work evaluates, by isobolographic analysis, the interactions between the cholinergic indirect agonist neostigmine (NEO) and NSAIDs drugs, using a chemical algesiometric test. 3. Intraperitoneal (i.p.) or intrathecal (i.t.) administration of NEO and of the different NSAIDs produced dose-dependent antinociception in the acetic acid writhing test of the mouse. 4. The i.p. or i.t. co-administration of fixed ratios of ED(50) fractions of NSAIDs and NEO, resulted to be synergistic or supra-additive for the combinations ketoprofen (KETO) and NEO, paracetamol (PARA) and NEO) and diclofenac (DICLO) and NEO administered i.p. However, the same combinations administered i.t. were only additive. In addition, the combinations meloxicam (MELO) and NEO and piroxicam (PIRO) and NEO, administered either i.p. or i.t., were additive. 5. The results suggest that the co-administration of NEO with some NSAIDs (e.g. KETO, PARA or DICLO) resulted in a synergistic interaction, which may provide evidence of supraspinal antinociception modulation by the increased acetylcholine concentration in the synaptic cleft of cholinergic interneurons. The interaction obtained between neostigmine and the NSAIDs could carry important clinical implications.

Pharmacology of Peripheral Analgesia

Pain may begin in the periphery with activation of nociceptor transducers. The present article reviews the pharmacology of drug action at the level of the primary afferent by discussing the following: [1] agents which block transduction processes (vanilloids, sodium ion channel blockers, antiserotonergic agents, antipurinergic agents); [2] agents inhibiting the transducer site (opioids, cannabinoids, alpha adrenergic agents); [3] agents blocking transducer-based modulation processes (anti-inflammatories, antikinin agents, antitachykinins); and [4] agents which block primary afferent-related modification processes (antineurotrophins). There is a clear role for many of these agents in the treatment of inflammatory pain and they have potential benefits for neuropathic pain with peripheral triggers.

Excitatory nicotinic and desensitizing muscarinic (M2) effects on C-nociceptors in isolated rat skin

The actions of different cholinergic agonists and antagonists were investigated on nociceptive afferents using the rat skin-saphenous nerve preparation, in vitro. Nicotine was able to weakly excite C-nociceptors and to induce a mild sensitization to heat stimulation (in 77% of tested fibers) in a dose-dependent manner (10(-)6 to 10(-)5 m), but it caused no alteration in mechanical responsiveness tested with von Frey hairs. Muscarine did not induce a significant nociceptor excitation, but almost all fibers exhibited a marked desensitization to mechanical and heat stimuli in a dose-dependent manner (from 10(-)6 to 10(-)4 m). The muscarinic effects could be prevented by the general muscarinic antagonist scopolamine (10(-)5 m), by the M3 antagonist 1,1-dimethyl-4-diphenylacetoxypiperidium oxide (10(-)6 m) co-applied with the M2 antagonist gallamine (10(-)5 m), and by gallamine alone. As positive control we used the relatively M2-selective agonist arecaidine (10(-)6 to 10(-)5 m), obtaining a similar desensitizing effect as with muscarine. Finally, we performed an immunocytochemical study that demonstrated the presence of M2 but not M3 receptors in thin epidermal nerve fibers of the rat hairy skin. Altogether, these data demonstrate opposite effects of nicotinic and muscarinic receptor stimulation on cutaneous nociceptors. M2 receptor-mediated depression of nociceptive responsiveness may convey a therapeutic, i.e., analgesic or antinociceptive, potential.