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Xavier Paqueron

Publications and source records attributed to Xavier Paqueron.

8 recordsLinked to original sources
PubMed2004

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

BACKGROUND: The 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. METHODS: Fifty-two patients had their arm randomly placed either alongside their body (group A) or in 90 degrees 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. RESULTS: Phantom 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). CONCLUSIONS: This 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.

Adult↗
PubMed2004

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.

Adult↗
PubMed2003

Plasticity in action of intrathecal clonidine to mechanical but not thermal nociception after peripheral nerve injury.

BACKGROUND: Intrathecal clonidine reduces tactile allodynia in animal models of neuropathic pain, and this effect is blocked by atropine. However, the role of tonic spinal cholinergic activity and its interaction with alpha2-adrenergic systems in normal and neuropathic conditions and to different sensory methods has not been systematically examined. The authors examined cholinergic receptor involvement in thermal and mechanical sensitivity in normal and neuropathic animals and its interaction with intrathecal clonidine. METHODS: Normal rats and rats that received L5/L6 spinal nerve ligation were tested with acute radiant heat, paw pressure, and punctate mechanical stimulation before and after the intrathecal administration of saline, the muscarinic receptor antagonist, atropine, or a toxin to destroy cholinergic neurons, and then after intrathecal clonidine. RESULTS: Atropine, the cholinergic neuronal toxin, and saline did not alter baseline withdrawal thresholds. In nerve-injured rats, neither saline nor atropine altered antinociception from clonidine to a thermal stimulus, but atropine reduced the effect of clonidine to von Frey filament withdrawal threshold (34 +/- 5.6 vs. 14 +/- 5.8 g [mean +/- SEM], saline vs. atropine; P < 0.05) and to withdrawal threshold to paw pressure after clonidine (174 +/- 18 g vs. 137 +/- 16 g, saline vs. atropine; P < 0.05). CONCLUSIONS: These data suggest that after nerve injury, mechanical but not thermal antinociception from intrathecal clonidine relies on a muscarinic interaction, because only mechanical antinociception was antagonized by atropine. These results do not favor a regulation of nociceptive transmission by a tonic release of acetylcholine in nerve-injured rats.

Acetylcholine↗
PubMed2002

Detection of brain death onset using the bispectral index in severely comatose patients.

OBJECTIVES: To evaluate the accuracy of bispectral index (BIS) monitoring for the diagnosis of brain death in severely comatose patients. DESIGN: A prospective study in an intensive care unit of a university hospital. POPULATION: Fifty-six severely comatose patients (Glasgow Coma Score < or = 5) admitted to the ICU mainly because of intracerebral hemorrhage, head injury, or postanoxic coma. METHODS: BIS was recorded continuously during the hospitalization in the ICU. Where necessary, clinical brain death was confirmed by EEG or cerebral angiography. MEASUREMENTS AND RESULTS: Twelve patients were already clinically brain dead at the time of admission, and their individual BIS values were 0. In each of these 12 patients brain death was thereafter confirmed by EEG or cerebral angiography. Forty-four patients were not clinically brain-dead at the time of admission, and their individual BIS values were between 20 and 79. Twenty-seven of these patients became brain-dead, and their individual BIS values dropped to 0 in a few hours to a few days. In these 27 patients EEG or cerebral angiography was performed after the BIS value decreased to 0 and confirmed brain death in all cases. Seventeen patients who did not become brain dead during their hospitalization in the ICU had persistent electrocerebral activity on EEG, and their average BIS values remained above 35. CONCLUSION: BIS can be used in severely comatose patients as an assessment of brain death onset, enabling appropriate scheduling of either EEG or cerebral angiography to confirm brain death.

Brain Death↗
PubMed2002

The clinical efficacy and pharmacokinetics of intraperitoneal ropivacaine for laparoscopic cholecystectomy.

UNLABELLED: Postoperative pain after laparoscopic surgery is less than after laparotomy, and patients may benefit from an intraperitoneal injection of local anesthetic. Thirty-seven ASA physical status I or II patients received in double-blinded fashion 20 mL of 0.9% saline solution (placebo), ropivacaine 0.25% (Rop 0.25%), or ropivacaine 0.75% (Rop 0.75%) immediately after trocar placement and at the end of surgery. We measured pain and morphine consumption until 20 h after surgery. Plasma ropivacaine concentrations were measured. The three groups were comparable for shoulder pain, parietal pain, and incidence of side effects. Visceral pain at rest, during cough, and on movement and total consumption of morphine were significantly smaller in Groups Rop 0.25% and Rop 0.75% when compared with Placebo. Although no adverse effect occurred in any patient, the largest dose led to large plasma concentrations of ropivacaine (2.93 +/- 2.46 microg/mL and 3.76 +/- 3.01 microg/mL after the first and second injection, respectively). We conclude that intraperitoneal administration of ropivacaine before and after surgery significantly decreases postoperative pain. Because the smaller dosage (2 x 50 mg) provided similar analgesia and was associated with significantly smaller plasma concentrations than the larger dosage (2 x 150 mg), this smaller dosage seems more appropriate. IMPLICATIONS: Intraperitoneal ropivacaine 100 mg injected during laparoscopic cholecystectomy significantly decreased postoperative pain when compared with injection of intraperitoneal placebo. At this dose, plasma concentrations remained in the nontoxic range,

Amides↗
PubMed2002

Brachial plexus nerve block exhibits prolonged duration in the elderly.

BACKGROUND: Upper limb trauma occurs frequently in elderly patients for whom peripheral nerve blocks are often preferred for anesthesia. The characteristics of such regional blocks have, however, never been described in an elderly population. Therefore, the authors assessed prospectively the onset and duration of upper extremity peripheral nerve block (the mid-humeral block) in elderly and young patients undergoing emergency upper extremity surgery. METHODS: Consecutive patients aged > 70 yr or < 70 yr received a mid-humeral block with a small volume of ropivacaine, 0.75%. Five milliliters was injected onto each of the musculocutaneous, radial, ulnar, and median nerves. Time to complete sensory and motor block and durations of complete sensory and motor block were assessed. Results are shown as median and its 95% confidence interval. RESULTS: Median ages were 77 yr (95% CI, 72-81 yr) and 39 yr (95% CI, 27-46 yr) in the two groups. Both groups had similar times to complete sensory blockade. The elderly group had longer durations of complete sensory (390 min [range, 280-435 min] vs.150 min [range, 105-160 min]; P< 0.05) and motor (357 min [range, 270-475 min] vs. 150 min [range, 90-210 min]; P< 0.05) blockade. Duration of complete sensory block was significantly correlated with age (rho = 0.56; P< 0.05). CONCLUSIONS: Age is a major determinant of duration of complete motor and sensory blockade with peripheral nerve block, perhaps reflecting increased sensitivity to conduction failure from local anesthetic agents in peripheral nerves in the elderly population.

Adult↗
PubMedDate not supplied

An unusual case of painful phantom-limb sensations during regional anesthesia.

OBJECTIVE: The objective of this article is to describe a late-onset phantom-limb pain during a continuous analgesic popliteal nerve block after foot surgery and its alleviation and recurrence when stopping and resuming the local anesthetic infusion. CASE REPORT: A 29-year-old woman undergoing a left hallux valgus repair received a continuous popliteal sciatic nerve block for postoperative analgesia. Postoperatively, 6 hours after the commencement of a ropivacaine 0.2% infusion, she reported feelings of tingling, clenching pain, and missing-limb sensation below the ankle. The surgical site remained painless. Sensation elicited by touch and propioception were normally perceived. Only sensations for pinprick and heat were impaired. The ropivacaine infusion was stopped, followed 2.5 hours later by the complete regression of any abnormal sensation. Meanwhile, pain at the surgical site was scored at 50 mm on a 100-mm visual analogic scale. As the infusion of ropivacaine was resumed, the abnormal sensations reappeared. The catheter was removed, and abnormal sensations again disappeared. The patient was discharged from hospital without further complications. CONCLUSIONS: This observation suggests that phantom-limb pain can be of late-onset and might occur during a continuous infusion of low-concentration local anesthetic responsible only for an analgesic block, as shown by the fact that only thermal and pinprick sensations, known to depend on Adelta-fibers and C-fibers, were altered. Therefore, this case contradicts the usual belief that a profound block is necessary to elicit phantom-limb pain.

Adult↗