Perineural clonidine does not prolong levobupivacaine 0.5% after sciatic nerve block using the Labat approach in foot and ankle surgery.

BACKGROUND: There is controversy about the effectiveness of perineural clonidine used as an adjuvant to local anesthetics. This study investigated whether the addition of 150 µg clonidine to 0.5% levobupivacaine used for posterior sciatic nerve block would prolong the duration of analgesia. METHODS: This double-blind, prospective trial compared the analgesic characteristics of 20 mL plain levobupivacaine versus 20 mL levobupivacaine 0.5% plus 150 µg clonidine in a posterior sciatic nerve block (Labat approach) for foot and ankle surgery. Sixty patients were randomized and allocated to receive either levobupivacaine alone or levobupivacaine plus clonidine, to find a 30% prolongation of analgesia with the adjuvant, using the same SD. The onset and duration of the block (time from completion of block administration to first morphine request), the hemodynamic changes during surgery, the need for rescue analgesia, and technical or neurologic complications were assessed over a 24-hour period. RESULTS: The onset of sensory block (in minutes) was similar in the levobupivacaine and levobupivacaine plus clonidine groups (10 [5-20] vs 10 [5-23] minutes, median [interquartile range], respectively), as was the time to first request of pain medication (1215 [920-1530] vs 1275 [1067-1360] minutes, respectively). However, during surgery, statistically significantly more subjects in the levobupivacaine plus clonidine group than the levobupivacaine group experienced a decrease of more than 20% in systolic arterial pressure (50% vs 28% of patients, respectively; P < 0.028). No complications were noted in either group over 24 hours. CONCLUSIONS: Addition of 150 µg clonidine to 20 mL of levobupivacaine 0.5% in posterior gluteal (Labat) sciatic nerve block did not prolong the duration of analgesia but had a slight effect on systolic arterial pressure.

Levobupivacaine 0.5% provides longer analgesia after sciatic nerve block using the Labat approach than the same dose of ropivacaine in foot and ankle surgery.

BACKGROUND: Levobupivacaine and ropivacaine are 2 left enantiomeric molecules frequently used for peripheral nerve blocks because of their safe clinical profile. Levobupivacaine is more lipophilic and theoretically more potent than ropivacaine, but clinical studies show conflicting results in terms of anesthetic and analgesic characteristics. We hypothesized that the pure S-enantiomer of bupivacaine provides longer-lasting analgesia than ropivacaine. METHODS: We compared the analgesic characteristics of 20 mL levobupivacaine versus 20 mL ropivacaine 0.5% in a posterior sciatic nerve block (Labat approach) for foot and ankle surgery. In a double-blind, randomized, prospective design, 80 patients received either substance. We assessed the onset, duration, and success of the block, and the need for rescue analgesia and technical or neurologic complications over 24 hours. RESULTS: The onset of sensory block (minutes) and the success rate were similar in levobupivacaine and ropivacaine groups (onset, 15 minutes [5-40 minutes] vs 15 minutes [5-60 minutes], respectively; success rate, 90% vs 92.5%). The average time for the first request of pain medication provided by 20 mL levobupivacaine 0.5% was significantly longer than with ropivacaine (1605 minutes [575-2400 minutes] vs 1035 minutes [590-1500 minutes], P < 0.001). The need for postoperative rescue analgesia was higher in the ropivacaine group (37 of 40 [92.5%] vs 30 of 40 [75%], P < 0.034). No complications were noted in either group at 24 hours. CONCLUSION: Twenty milliliters levobupivacaine 0.5% in posterior gluteal (Labat) sciatic nerve block provided longer-lasting analgesia after foot and ankle surgery compared with the same dose of ropivacaine.

A new anatomical technique to investigate nerves by imagery.

INTRODUCTION: We describe a novel post mortem technique that makes it possible to visualise the nerve structure of the brachial plexus using imaging. MATERIALS AND METHODS: We dissected in situ the brachial plexus of a cadaver preserved by formaldehyde. A preparation composed of a mixture of baryte powder, water and colorant, was applied to all sides of the brachial plexus and blood vessels of the region under study. A high resolution CT scan was performed. With the aid of Mimics (Materialise) software, segmentation of all the nerve and vascular structures on each of the 650 slices obtained was performed. The Mimics software then compiled all the slices to generate a 3-dimensional STL image. RESULTS: The image obtained was printed with a stereolythography printer, to produce a plastic model representing part of the cervico-thoracic spinal cord, the ribs, sternum, scapula, humerus, and clavicle, with the left brachial plexus and the subclavian, axillary and brachial veins and arteries. CONCLUSIONS: This technique has the potential for a wide range of uses: for teaching anatomy, to improve teaching of medical techniques, 3-dimensional modelisation of other nerve structures. The advantage is that the model obtained is a faithful and realistic reproduction.

No differences between 20, 30, or 40 mL ropivacaine 0.5% in continuous lateral popliteal sciatic-nerve block.

BACKGROUND AND OBJECTIVES: The aim of this study was to compare the anesthetic and analgesic characteristics of the administration of an initial bolus of 20, 30, or 40 mL of ropivacaine 0.5% through a lateral popliteal sciatic catheter. METHODS: Sixty patients scheduled for foot surgery under continuous sciatic lateral popliteal nerve block were included in this double-blinded study. Patients were randomly assigned to 1 of 3 groups: 20 mL, 30 mL, or 40 mL of ropivacaine 0.5%. Time to obtain a complete sensory block and duration of analgesia were recorded. Failure of the continuous block and complications such as technical or neurologic problems were noted. RESULTS: Data are presented as mean +/- SD, median and ranges, or percent of patients and were compared by application of analysis of variance or Kruskal-Wallis when required. Time to complete sensory block (31 [10-70] v 25 [5-50] v 25 [5-40] min), percentage of failure (5% v 5% v 0%), and duration of action (995 [278-1,800] v 967 [420-2,175] v 915 [190-1,900] min) were not statistically different between 20 mL, 30 mL, and 40 mL ropivacaine 0.5% groups, respectively. No complications were noted. CONCLUSIONS: This dose-response study shows that 20 mL of ropivacaine 0.5% injected through an indwelling lateral popliteal catheter is the optimal dose for foot surgery. Higher doses of 30 mL or 40 mL did not provide any further advantage.

Intrathecal sufentanil is more potent than intravenous for postoperative analgesia after total-hip replacement.

BACKGROUND AND OBJECTIVES: In our clinical experience, sufentanil is more effective when administered intrathecally than intravenously. To test this hypothesis, we compared the analgesic characteristics of 7.5 microg of intrathecal or intravenous sufentanil for pain relief after total-hip replacement. METHODS: A randomized, double-blind study was conducted of 40 patients older than 75 years who experienced total-hip arthroplasty in which continuous spinal anesthesia was administered. In the recovery room, as soon as a pain score higher than 3 on a scale of 10 on a visual analog scale was reported, either 7.5 microg intrathecal or 7.5 microg intravenous sufentanil were given. If the pain score remained higher than 3 at 20 minutes after sufentanil administration,1.25 mg of "rescue" intrathecal bupivacaine were given. RESULTS: During the first 20 minutes after intrathecal or intravenous injection, a significantly faster relief of pain was observed for the intrathecal group from 2.5 until 20 minutes. Significantly, more patients needed rescue bupivacaine in the intravenous group (7 of 20 v 0 of 20, P < .008), whereas significantly more patients in the intrathecal group reached a pain score of 0 (20 of 20 v 9 of 20, P < .001). The time to the first analgesic intervention for a pain score greater than 3 was significantly longer in the intrathecal group (224 +/- 100 v 98 +/- 60 minutes, P < .001). Pruritus was observed only in 5 patients of the intrathecal group (P < .047), whereas peripheral oxygen saturation under 95% was observed only in 6 patients in the intravenous group (P < .045). CONCLUSIONS: After total-hip replacement, intrathecal route of sufentanil administration rapidly offers excellent analgesia of better quality and longer duration when compared with the intravenous route.

Duration of analgesia is similar when 15, 20, 25 and 30 mL of ropivacaine 0.5% are administered via a femoral catheter.

PURPOSE: This dose-response study was designed to determine the most appropriate dose of ropivacaine 0.5% injected via an indwelling femoral catheter for perioperative peripheral analgesia for total knee replacement (TKR). METHODS: 84 patients were allocated randomly to four groups and received, via a femoral catheter, either 15, 20, 25 or 30 mL of ropivacaine 0.5% in a double-blind fashion. An anterior sciatic block with 20 mL bupivacaine 0.5% was also performed. The evolution of sensory block of femoral, obturator and lateral femoral cutaneous nerves and motor block of femoral nerve were tested every five minutes during the first 30 min. The percentage of patients with complete sensory block of both femoral and obturator nerves determined success rate. General anesthesia was then induced. After surgery, patient-controlled analgesia (PCA) with ropivacaine 0.2% was available via the femoral catheter. The interval between the initial injection and the first PCA administration determined duration of action. RESULTS: The duration of action was not different between the four solutions tested i.e., 534 +/- 379 min for 15 mL, 799 +/- 364 min for 20 mL, 624 +/- 342 min for 25 mL and 644 +/- 266 min for 30 mL. The percentage of patients with complete sensory femoral and obturator blocks was, respectively, 60%, 95%, 85% and 70% for 15, 20, 25 and 30 mL (P = 0.008/15 mL vs 20 mL). CONCLUSION: Although there is no difference in duration of analgesia, because of better sensory spread, 20 mL of ropivacaine 0.5% appears to be the most appropriate dose for peripheral analgesia after TKR.

Skull base cerebrospinal fluid fistula: a novel detection method based on two-dimensional electrophoresis.

BACKGROUND: The detection of the presence of cerebrospinal fluid (CSF) in nasal secretions contaminated with blood and mucus remains a challenging clinical problem. METHODS: A prospective study was conducted from November 1998 to February 2002, including 42 patients. Samples (250 microL) of nasal secretions were analyzed by two-dimensional electrophoresis (2-DE). Plasma, mucus, and CSF were identified by specific proteins markers corresponding to characteristic trains of spots. Intrathecal injection of fluorescein followed by the detection of fluorescein on endoscopic examination of the nasal cavities was considered a positive reference for CSF rhinorrhea. RESULTS: In all cases of positive fluorescein test, we unambiguously observed the presence of several specific CSF markers onto the 2-DE gels. Conversely, all negative fluorescein tests were associated with the absence of CSF-specific spots. CONCLUSIONS: Two-DE analyses of biologic fluids of nasal origin should be considered as a reliable diagnostic tool in case of suspicion of CSF leak.

Isobaric versus hypobaric spinal bupivacaine for total hip arthroplasty in the lateral position.

UNLABELLED: Total hip arthroplasty (THA) is frequently performed under spinal anesthesia using either isobaric or hypobaric anesthetic solution. However, these two solutions have never been compared under similar surgical conditions. In the present study, we compared the anesthetic and hemodynamic effects of isobaric and hypobaric bupivacaine in 40 ASA physical status I-II patients undergoing THA in the lateral decubitus position under spinal anesthesia. With operative side up, patients randomly received, in a double-blinded manner, a spinal injection of 3.5 mL (17.5 mg) of plain bupivacaine mixed with either 1.5 mL of normal saline (isobaric group) or 1.5 mL of distilled water (hypobaric group). Sensory level and degree of motor block were evaluated on the nondependent and dependent sides until regression to L2 and total motor recovery. Hemodynamic changes during the first 45 min after spinal injection, and the time between spinal administration and first analgesic for a pain score >3 (on a 0-10 scale) were noted. Demographic characteristics of both groups were comparable. Upper sensory level and maximal degree of motor block were comparable between the operative and nonoperative sides in each group and between corresponding sides in both groups. Compared with the isobaric group, in the hypobaric group there was a prolonged time to sensory regression to L2 on the operative side (287 +/- 51 versus 242 +/- 36 min, P < 0.004) and a prolonged time to first analgesic (290 +/- 46 versus 237 +/- 39 min, P < 0.001). No difference in quality of motor block was noted at the end of surgery. Hemodynamic changes were comparable. We conclude that for THA in the lateral position, spinal hypobaric bupivacaine seems to be superior to isobaric in that it prolongs the sensory block on the operative side and delays the use of analgesics after surgery without further compromising hemodynamic stability. IMPLICATIONS: For total hip arthroplasty in the lateral position, spinal hypobaric bupivacaine compared with isobaric prolonged sensory block at the operative side and delayed the time to first analgesic.

Cerebrospinal fluid density influences extent of plain bupivacaine spinal anesthesia.

BACKGROUND: The attempts to explain the unpredictability of extent of spinal block provided by plain local anesthetic solutions have resulted in many clinical reports; however, causes of this uncertainty are as yet unknown. Recently, normal values of the human cerebrospinal fluid densities have been studied showing important interindividual variations, especially between females and males. The current study was designed to evaluate as primary endpoint the influence of cerebrospinal fluid density values on the extent of spinal block with plain bupivacaine. The ancillary endpoints were search of factors explaining the interindividual differences in cerebrospinal fluid density values reported and determination of the relation between upper extent and regression of spinal anesthesia. METHODS: Sixty-four consecutive patients undergoing peripheral orthopedic surgery with spinal block were enrolled. Spinal anesthesia was performed in the lateral decubitus position with the operated side upward. Two milliliters of cerebrospinal fluid was sampled before injection of 3 ml plain bupivacaine 0.5%. The patient was immediately turned supine and remained in the horizontal position until the end of the study. Maximal sensory block level and time to sensory regression to L4 were determined for each patient enrolled. Cerebrospinal fluid and bupivacaine densities as well as cerebrospinal proteins, glucose, sodium, and chloride concentrations were measured. RESULTS: A highly significant correlation between cerebrospinal fluid density and maximal sensory block level was found (P = 0.0004). However, this correlation was poorly predictive (R(2) = 0.37). Cerebrospinal fluid density, proteins, and glucose concentrations were significantly higher in men than in women: 1.000567 +/- 0.000091 versus 1.000501 +/- 0.000109 g/ml (P = 0.014), 0.46 +/- 0.18 versus 0.32 +/- 0.13 g/l (P = 0.001), and 3.27 +/- 0.7 versus 2.93 +/- 0.5 mM (P = 0.023), respectively. A highly significant (P = 0.0004) and predictive (R(2) = 0.73) inverse correlation was found between maximal upper sensory extent and sensory regression to L4. CONCLUSION: These findings indicate an influence of cerebrospinal fluid density on subarachnoid distribution of 3 ml plain bupivacaine 0.5% and show that with higher cerebrospinal fluid densities, a higher spinal block level can be expected.