Marc Gentili

Lack of Impact of Intravenous Lidocaine on Analgesia, Functional Recovery, and Nociceptive Pain Threshold after Total Hip Arthroplasty

Background:The analgesic effect of perioperative low doses of intravenous lidocaine has been demonstrated after abdominal surgery. This study aimed to evaluate whether a continuous intravenous low-dose lidocaine infusion reduced postoperative pain and modified nociceptive pain threshold after total hip arthroplasty. Methods:Sixty patients participated in this randomized double-blinded study. Patients received lidocaine 1% (lidocaine group) with a 1.5 mg/kg−1 intravenous bolus in 10 min followed by a 1.5 mg · kg−1 · h−1 intravenous infusion or saline (control group). These regimens were started 30 min before surgical incision and stopped 1h after skin closure. Lidocaine blood concentrations were measured at the end of administration. In both groups, postoperative analgesia was provided exclusively by patient-controlled intravenous morphine. Pain scores, morphine consumption, and operative hip flexion were recorded over 48 h. In addition, pressure pain thresholds and the extent of hyperalgesia around surgical incision were systematically measured at 24 and 48 h. Results:In comparison with the placebo, lidocaine did not induce any opioid-sparing effect during the first 24 h (median [25–75% interquartile range]; 17 mg [9–28] vs. 15 mg [8–23]; P = 0.54). There was no significant difference regarding the effects of lidocaine and placebo on pain score, pressure pain thresholds, extent in the area of hyperalgesia, and maximal degree of active hip flexion tolerated. Mean plasma lidocaine concentration was 2.1 ± 0.4 &mgr;g/ml. Conclusion:Low dose perioperative intravenous lidocaine after total hip arthroplasty offers no beneficial effect on postoperative analgesia and does not modify pressure and tactile pain thresholds.

Infraclavicular block with lateral approach and nerve stimulation: Extent of anesthesia and adverse effects

Background and Objectives The infraclavicular approach to the brachial plexus is little used despite theoretical advantages of the technique. Using a vertical paracoracoid approach, we assessed the extent of the sensory block and the incidence of adverse effects. Methods After obtaining informed consent, 100 patients undergoing surgical procedures distal to the elbow were evaluated. The block was performed using a peripheral nerve stimulator. The puncture site was located in the infraclavicular fossa; the direction of the insulated needle was perpendicular to the skin. Motor response was sought in the hand or wrist at ≤ 0.6 mA. A total of 40 mL of 1.5% mepivacaine was administered as a single injection. The sensory block was evaluated every 5 minutes for 30 minutes before surgery in the cutaneous distribution of terminal branches of the brachial plexus. Results When one considers the cutaneous distributions of the median, ulnar, radial, and musculocutaneous nerves, the success rate was 89% for surgery without need for additional peripheral nerve blocks or general anesthesia. In contrast, cutaneous areas innervated by the axillary and medial cutaneous nerves were rarely anesthetized. We were unable to demonstrate a correlation between the intensity of the stimulation and the success of the block. On the other hand, a correlation was found between tourniquet sensation and the absence of anesthesia of the medial cutaneous nerve of the arm. Local anesthetic toxicity, Horner’s syndrome, and vascular puncture were respectively observed in 1%, 4%, and 5% of cases. The depth of the needle introduction was correlated with the body mass index (P < .001; r = .63). Conclusion Single injection infraclavicular block, using a vertical paracoracoid approach, appears suitable for surgery distal to the elbow. Selective anesthesia of the medial cutaneous nerve is useful in improving tolerance of the tourniquet.

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-1&bgr;, 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.

A comparison of a single-stimulation lateral infraclavicular plexus block with a triple-stimulation axillary block

Background and Objectives A single-stimulation infraclavicular brachial plexus block (ICB) is safe and easy to perform, although underused. This technique was compared with a triple-stimulation axillary block (AxB). Methods One hundred patients scheduled for hand and forearm surgery were randomly allocated to 2 groups. ICB was performed with the needle inserted above the coracoid process in the upper lateral angle of the infraclavicular fossa and directed vertically until nerve stimulation elicited a distal motor response (median, radial, or ulnar). A single 40-mL bolus of ropivacaine 0.75% was injected. In the AxB group, 3 stimulations were performed to identify median or ulnar, radial, and musculocutaneous nerves, followed by an infiltration near the medial brachial and antebrachial cutaneous nerves. The same 40 mL ofropivacaine 0.75% was injected. Sensory and motor blocks were assessed at 5-minute intervals over 30 minutes. Results The time to block performance was shorter in the ICB than in the AxB group (2.5 ± 1.9 minutes v 6.0 ± 2.8 minutes, P < .001). The success rate (complete block in median, radial, ulnar, musculocutaneous, and medial antebrachial cutaneous nerves) was comparable in the 2 groups (90% v 88% in groups ICB and AxB, respectively). Block extension was comparable, except for a higher rate of block completion in the axillary nerve distribution in group ICB and in the medial brachial cutaneous nerve in group AxB. The onset of each nerve block was comparable except for a faster onset for the musculocutaneous nerve in group AxB (8 ± 3 v 10 ± 5 minutes). Conclusion A single shot ICB is equally effective as a triple-nerve stimulation AxB. Reg Anesth Pain Med 2003;28:89-94.

The efficacy of a glial inhibitor, minocycline, for preventing persistent pain after lumbar discectomy: A randomized, double-blind, controlled study

&NA; Perioperative minocycline administration for 8 days after lumbar discectomy does not improve persistent pain. &NA; Minocycline strongly inhibits microglial activation, which contributes to central sensitization, a major mechanism underlying chronic pain development. We hypothesized that the perioperative administration of minocycline might decrease persistent pain after lumbar discectomy. We randomly assigned 100 patients undergoing scheduled lumbar discectomy to placebo and minocycline groups. The minocycline group received 100 mg minocycline orally, twice daily, beginning the evening before surgery and continuing for 8 days. The primary outcome was the change in lower limb pain intensity at rest between baseline and 3 months. Secondary outcomes were pain intensity on movement, the incidence of persistent pain and chronic neuropathic pain, back pain intensity at rest and on movement, and changes in Neuropathic Pain Symptom Inventory, Brief Pain Inventory, and Roland‐Morris scores at 3 months. An intention‐to‐treat analysis was performed for patients assessed from the day before surgery to 3 months. The decrease in lower limb pain intensity was similar in the placebo and minocycline groups, both at rest −1.7 ± 1.6 vs −2.3 ± 2.4 and on movement −2.5 ± 2.1 vs −3.4 ± 2.9. The incidence and intensity of neuropathic pain and functional scores did not differ between the minocycline and placebo groups. Exploratory analysis suggested that minocycline might be effective in a subgroup of patients with predominantly deep spontaneous pain at baseline. Perioperative minocycline administration for 8 days does not improve persistent pain after lumbar discectomy.

Antinociceptive effect of resveratrol in carrageenan-evoked hyperalgesia in rats: prolonged effect related to COX-2 expression impairment.

Abstract Resveratrol is a natural polyphenol that protects from cancer and cardiovascular diseases. Resveratrol is able to induce apoptotic cell death and it inhibits the cyclooxygenase (COX) cascade. We measured the antinociceptive effect of resveratrol on carrageenan‐induced hyperalgesia, prostaglandin‐E2 (PGE2) concentration in CSF and COX‐1/COX‐2 gene expression in the spinal cord and dorsal root ganglion (DRG) in rats. Resveratrol induced a prolonged antinociceptive effect, which was correlated to the inhibition of COX‐2 mRNA increase in DRG and cord elicited by carrageenan. An increase in the basal threshold of mechanical nociception was also observed with resveratrol in the absence of any inflammatory insult. A rapid bilateralisation of COX‐2 mRNA production, not accompanied by a parallel increase in c‐Fos expression, was observed in spinal cord three hours after the inflammatory insult. This increase in COX‐2 mRNA concentration in the spinal cord on the opposite side of the inflammatory insult was abolished by resveratrol. In conclusion, the antinociceptive effect exhibited by resveratrol was related to the prevention of COX‐2 mRNA increase induced by carrageenan. Resveratrol also prevented the bilateralisation of COX‐2 expression. The later effect, together with the prolonged analgesia induced by a single injection, may be of great benefit for preventing chronic pain states often seen after inflammatory insults.

Postoperative analgesia by intraarticular clonidine and neostigmine in patients undergoing knee arthroscopy

Background and Objective Clonidine and neostigmine have a central mechanism of analgesic action and are synergistic when given intrathecally. Both drugs also have a peripheral analgesic effect. The purpose of this study was to compare the analgesic effect of intraarticular clonidine and neostigmine, used separately and in combination, in patients undergoing knee arthroscopy. Methods Eighty-four American Society of Anesthesiologists (ASA) I and II patients scheduled for meniscus repair under arthroscopy were allocated randomly in 6 groups to receive in a double-blind manner at the end of surgery 150 μg of intraarticular clonidine with subcutaneous saline, 500 μg of intraarticular neostigmine with subcutaneous saline, an intraarticular combination of 150 μg of clonidine and 500 μg of neostigmine with subcutaneous saline, 150 μg of intraarticular clonidine with 500 μg of subcutaneous neostigmine, 500 μg of intraarticular neostigmine with 150 μg of subcutaneous clonidine, or intraarticular and subcutaneous isotonic saline. Postoperative pain scores were measured on a visual analog scale (VAS) at rest and on mobilization. Paracetamol (1 g) was given as a rescue medication when pain score was greater than 40. Results VAS scores at rest and on mobilization were lower in the first 5 groups compared with the intraarticular saline group (P < .05), but no significant difference was documented between the treated groups. The time to the first paracetamol administration was shorter in the saline group compared with the other groups, and the paracetamol demand was also higher in this group. Forty-five percent of the patients who had received clonidine had at least 1 episode of hypotension versus 4% of those who did not (P < .01). The incidence of bradycardia was 20% and 0%, respectively (P = .01). The incidence of nausea was not statistically different in patients who did and did not receive neostigmine (43% v 36%, respectively). Conclusion Intraarticular administration of 150 μg of clonidine, 500 μg of neostigmine, or both produce postoperative analgesia, and the combination is not more effective.

Time sequence of sensory changes after upper extremity block: Swelling sensation is an early and accurate predictor of success

Background:Sensory assessment to estimate spread and effectiveness of a peripheral nerve block is difficult because no clinical test is specific for small sensory fibers. Occurrence of a swelling illusion (SI) during a peripheral nerve block corresponds to the impairment of small sensory fibers. The authors investigated the usefulness of SI in predicting successful peripheral nerve block by assessing the temporospatial correlation between progression of sensory impairment in cutaneous distributions anesthetized and localization of SI during peripheral nerve block installation. Methods:Interscalene, infracoracoid, or sciatic nerve blocks were performed using a nerve stimulator and 1.5% mepivacaine in 53 patients, with a total of 201 nerves to be anesthetized. Pinprick, cold, warm, touch, and proprioception were assessed every 3 min, while patients were asked to describe their perception of size and shape of their anesthetized limb and localization of these illusions. Data are presented as mean ± SD and percentage (95% confidence interval). Results:Failure occurred in 12 cutaneous distributions out of a total of 201 theoretically blocked nerves. SI appeared earlier than warmth impairment (4.3 ± 2.7 vs. 6.2 ± 2.0 min; P < 0.05), always corresponding to successfully anesthetized cutaneous distributions, with the exception of 1 patient, who developed SI in 2 cutaneous distributions while sensory testing indicated failure in 1 distribution. SI successfully predicted the blockade of a cutaneous distribution with a sensitivity of 1.00 (0.98–1.00), a specificity of 0.92 (0.65–0.99), and an accuracy of 0.99 (0.97–1.00). Conclusions:Swelling illusion may provide an early assessment of the success of a peripheral nerve block in unsedated patients.

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.

Influence of sensory and proprioceptive impairment on the development of phantom limb syndrome during regional anesthesia.

BackgroundThe relation between impairment of sensorimotor function and occurrence of phantom limb syndrome (PLS) during regional anesthesia has not been described. This study assessed the temporal relation between PLS and the progression of sensorimotor impairment during placement of a brachial plexus nerve block. MethodsFifty-two patients had their arm randomly placed either alongside their body (group A) or in 90° abduction (group B) immediately after brachial plexus nerve block placement. Responses to pin prick, cold, heat, touch, proprioception, and voluntary movement were assessed every 5 min for 60 min. Meanwhile, patients described their perceptions of the size, shape, and position of their anesthetized limb. ResultsPhantom limb syndrome occurred 19 ± 9 min after nerve block placement. Proprioception was impaired and abolished after 22 ± 9 and 43 ± 17 min, respectively (P < 0.05 vs. PLS onset). When PLS occurred, responses to pin prick, cold, heat, and proprioception were abolished in 96, 94, 87, and 4% of patients, respectively. Patients were more likely to feel their anesthetized limb in adduction and in abduction in groups A and B (P < 0.05 vs. group A), respectively. After PLS had become motionless, two stereotyped positions were identified: arm adduction, elbow flexion, hand over the abdomen (68% of group A patients) and arm abduction, elbow flexion, hand held close to the homolateral ear (48% of group B patients). ConclusionsThis study provides a better understanding of the determinants of PLS by showing that the final position of PLS is related both to the abolition of proprioception and the initial position of the anesthetized limb.