Pierre-Antoine Laloë

Combined ultrasound and neurostimulation guidance for popliteal sciatic nerve block: a prospective, randomized comparison with neurostimulation alone.

BACKGROUND:Ultrasound imaging, an effective tool to localize peripheral nerves, may facilitate block performance. However, its usefulness during popliteal sciatic nerve block has not been assessed. METHODS:In this prospective, randomized, patient-blinded study, we compared the block time (as the primary end-point) of a popliteal sciatic nerve block with double-injection performed using anatomical landmarks and neurostimulation (NS group; n = 30) versus combined ultrasound and neurostimulation guidance (US-NS group; n = 30). Each block procedure was performed by a single operator. Correct needle placement was defined by a minimal stimulating current ≤0.5 mA, or, in the US-NS group, by mobilization of the nerve by the needle shaft even if the minimal stimulating current >0.5 mA. Ten milliliter levobupivacaine 0.5% was administered separately on the tibial and common peroneal nerves without needle adjustment to improve the spread of anesthetic in the US-NS group. All procedures were video-recorded, and a maximum of 7 min was allowed to perform the block. Successful block was defined as complete loss of cold sensation in the sciatic distribution and an inability to perform a plantar and dorsal flexion of the foot at 30 min. RESULTS:Five patients in the NS group and three in US-NS group were excluded from the study for prolonged procedure. Block time was not significantly different between groups. The number of needle passes was lower only for the detection of the first nerve in the US-NS group (1 [1–2] vs 2 [1–6]; P < 0.01). A greater success rate was observed at 30 min in the US-NS group (65% vs 16%; P < 0.001). CONCLUSIONS:Combined ultrasound and neurostimulation guidance does not decrease block time but increases the success rate of popliteal sciatic nerve block observed at 30 min.

Does monitoring bispectral index or spectral entropy reduce sevoflurane use

A decrease in volatile anesthetic consumption has been demonstrated using bispectral index (BIS), whereas data concerning spectral entropy are lacking. One hundred and forty adult patients scheduled for surgical procedures lasting more than 1 h were prospectively randomized to receive an anesthetic controlled either by BIS or by spectral entropy or solely by clinical variables. Anesthesia was induced with propofol and sufentanil. Sufentanil was infused continuously thereafter. Sevoflurane was administered in 1 L/min O2/N2O. The sevoflurane concentration was adjusted according to conventional clinical variables in the standard practice group, whereas the 40–60 interval was applied for the BIS and spectral entropy-guided groups. The sevoflurane vaporizer was weighed before and after anesthesia, and consumption was calculated. Groups were comparable for demographic data except for weight (heavier in the spectral entropy-guided group, P < 0.05). Compared with standard practice, patients with BIS or spectral entropy monitoring required 29% less sevoflurane (normalized sevoflurane consumption to the weights of the patients and to the durations of anesthesia; both P < 0.03) and a similar sufentanil dose. An unintended improvement in the standard practice group (positive bias) was observed. In conclusion, BIS and spectral entropy monitoring have the same sparing effect of sevoflurane.

The Analgesia Nociception Index: a pilot study to evaluation of a new pain parameter during labor

BACKGROUND Objective pain assessment that is not subject to influences from either cultural or comprehension issues is desirable. Analysis of heart rate variability has been proposed as a potential method. This pilot study aimed to assess the performance of the PhysioDoloris™ analgesia monitor which calculates an Analgesia Nociception Index derived from heart rate variability. It was compared with visual analogical pain scores. METHODS Forty-five parturients who requested epidural analgesia were recruited. Simultaneous couplets of pain scores and Analgesia Nociception Index values were recorded every 5 min regardless of the presence or absence of uterine contractions. The relationship between indices was characterized, and a cut-off value of Analgesia Nociception Index corresponding to a visual analogical score >30 (range 0-100) was used to determine the positive and negative predictive value of the Analgesia Nociception Index. RESULTS There was a negative linear relationship between visual analogical pain scores and Analgesia Nociception Index values regardless of the presence of uterine contractions (regression coefficient ± SEM=-0.18 ± 0.032 for entire dataset). Uterine contraction significantly reduced the Analgesia Nociception Index (P<0.0001). Using a visual analogical pain score >30 to define a painful sensation, the lower 95% confidence limit for the Analgesia Nociception Index score was 49. CONCLUSION The Analgesia Nociception Index has an inverse linear relationship with visual analogical pain scores. Further studies are necessary to confirm the results of this pilot study and to look at the influence of epidural analgesia on the Analgesia Nociception Index.

A Comparison of the Deflecting-Tip Bronchial Blocker With a Wire-Guided Blocker or Left-Sided Double-Lumen Tube

OBJECTIVE To compare a new bronchial blocker, the Cohen blocker, with the Arndt blocker and a left double-lumen tube (DLT). DESIGN A prospective, randomized, controlled trial. SETTING University hospital. PARTICIPANTS Forty-eight patients undergoing lung surgery. INTERVENTION Intubation with 1 of the 3 devices. Comparisons among groups included (1) time for initial positioning, (2) degree of lung collapse at pleura opening, and (3) number of intraoperative fiberoptic examinations. MEASUREMENTS AND MAIN RESULTS Positioning of the Cohen blocker (256 [166-341] seconds; median [interquartile range]) took no longer compared with the Arndt blocker (253 [184-305] seconds), and there was a trend toward difference between the 2 blockers and the DLT (137 [102-199] seconds) (p = 0.07). The time to place the Cohen blocker was longer in cases of left bronchus occlusion compared with a right one (340 [300-450] v 170 [124-259] seconds, p = 0.02); they were similar in the Arndt group. The degree of lung collapse was different among groups (p = 0.05), but the difference between any pair did not reach statistical significance. The number of patients who required at least 1 additional FOB examination was not statistically different (50% of patients in each blocker group v 19% in the DLT group). CONCLUSIONS There was a trend toward a difference between times to place a bronchial blocker and the DLT. The Cohen blocker is more difficult to position in the left main bronchus than in the right one.

Ultrasound-Guided Transversus Abdominis Plane Block versus Continuous Wound Infusion for Post-Caesarean Analgesia: A Randomized Trial

Objective To compare the analgesic effect of ultrasound-guided Transversus Abdominis Plane (TAP) block versus Continuous Wound Infusion (CWI) with levobupivacaine after caesarean delivery. Methods We recruited parturients undergoing elective caesareans for this multicenter study. Following written informed consent, they received a spinal anaesthetic without intrathecal morphine for their caesarean section. The postoperative analgesia was randomized to either a bilateral ultrasound guided TAP block (levobupivicaine = 150 mg) or a CWI through an elastomeric pump for 48 hours (levobupivacaine = 150 mg the first day and 12.5 mg/h thereafter). Every woman received regular analgesics along with oral morphine if required. The primary outcome was comparison of the 48-hour area under the curve (AUC) pain scores. Secondary outcomes included morphine consumption, adverse events, and persistent pain one month postoperatively. Results Recruitment of 120 women was planned but the study was prematurely terminated due to the occurrence of generalized seizures in one patient of the TAP group. By then, 36 patients with TAP and 29 with CWI had completed the study. AUC of pain at rest and during mobilization were not significantly different: 50 [22.5–80] in TAP versus 50 [27.5–130] in CWI (P = 0.4) and 190 [130–240] versus 160 [112.5–247.5] (P = 0.5), respectively. Morphine consumption (0 [0–20] mg in the TAP group and 10 [0–32.5] mg in the CWI group (P = 0.09)) and persistent pain at one month were similar in both groups (respectively 29.6% and 26.6% (P = 0.73)). Conclusion In cases of morphine-free spinal anesthesia for cesarean delivery, no difference between TAP block and CWI for postoperative analgesia was suggested. TAP block may induce seizures in this specific context. Consequently, such a technique after a caesarean section cannot be recommended. Trial Registration ClinicalTrials.gov NCT01151943

The Comparability of Bispectral Index and State Entropy Index During Maintenance of Sufentanil-sevoflurane-nitrous Oxide Anesthesia

BACKGROUND:Manufacturers recommend maintaining Bispectral (BIS) or Spectral Entropy (State Entropy, SE) indexes between 40 and 60 during the maintenance of anesthesia. We compared these indexes during this period. METHODS:Data were obtained from 58 patients receiving sufentanil-sevoflurane-nitrous oxide anesthesia. The anesthesiologist was blinded to BIS and SE. Artifact-free concurrent BIS and SE values (7792 pairs), automatically recorded at 1-min intervals, were compared using Bland-Altman analysis, Kappa coefficient for agreement and crude proportion of agreement. The occurrence of errors of judgment (Type 1 defined as one parameter <40 and the other >60, or Type 2 defined as BIS and SE values on different sides of a threshold [40 or 60]) was also counted. RESULTS:Bias was −2 with limits of agreement of −18 and 9. Kappa BIS/SE obtained from all patients was 0.537 ± 0.147; crude agreement >0.80 was observed in 45% of patients. Type 1 number of errors of judgment corresponded to two instances. Median and interquartile values of Type 2 number of errors of judgment were 4.5 [3.0–6.0] when considering a difference between BIS and SE more than 5. CONCLUSION:Although limits of agreement between BIS and SE were large, Kappa value moderate, and crude agreement <0.80 in more than half of the patients, making completely contradictory decisions (e.g., deepening the anesthetic based on one parameter and lightening it based upon the other) would have been exceptional. More common would have been a risk of error between no change versus increasing or decreasing anesthetic depth.

Seizure After Aortic Clamp Release: A Bispectral Index Pitfall

A E HERE IS NO CONSENSUS on the best mode for operative central nervous system monitoring during c iac surgery. 1 Intraoperative electroencephalography (EEG) ar from being used routinely in part because the presence pecialized technician is required. Some teams use bispec ndex (BIS) monitoring as an alternative to EEG for the ion of cerebral hypoperfusion 2-4 and to reduce the risk wareness.5,6 However, Dahaba7 recently reviewed several cas eports and series concerning BIS and outlined the high ri isinterpretation by the BIS algorithm, because its values requently not in agreement with the clinically judged seda ypnotic state of the patients. The authors report a case of misinterpretation of BIS d seizure diagnosed on conventional EEG; both devices sed because the authors were learning BIS technology.

The Wire-Guided Endobronchial Blocker as a Solution To Provide One-Lung Ventilation When a Double-Lumen Endotracheal Tube Is Malpositioned

DOUBLE-LUMEN endotracheal tubes are the most commonly used tubes for lung isolation. The indications for use of bronchial blockers, such as the Univent single-lumen endotracheal tube with enclosed bronchial blocker (Fuji Systems Corporation, Tokyo, Japan),1 or the wire-guided endobronchial blocker (Cook Critical Care, Bloomington, IN)2, are debatable.3,4 The use of the wire-guided endobronchial blocker is reported for rescue in a patient who presented for thoracoscopy and for whom surgery was difficult because of an improperly positioned left-sided double-lumen endotracheal tube.

Ultrasound and neurostimulation-guided axillary brachial plexus block for resection of a hemodialysis fistula aneurysm.

An ASA III patient presenting with a voluminous hemodialysis fistula aneurysm at the elbow was scheduled for its resection. Axillary brachial plexus block was performed under ultrasound and neurostimulation guidance. Despite unexpected nerve positions in relation to pathological vascular anatomy, this combined approach resulted in an adequate block with a low volume of local anesthetic, without obvious vascular puncture or intraneural injection.

Multiplane Reconstruction Is Better Than Plain X-ray to Measure the Tracheobronchial Tree

To the Editor:—We read with interest Martin et al.’s study on the antiinflammatory effect of peripheral nerve block after total knee arthroplasty. We would be delighted to see such an outcome; however, we wish to raise the following questions on the conclusion drawn that peripheral nerve blocks have a clinical antiinflammatory effect, especially when there was no change in inflammatory mediator levels. This study’s primary outcome measure was IL-6 at 24 hours. Statistically it was powered to demonstrate a 50% reduction in IL-6 at 24 hours, with 20 patients per treatment arm. This study was not powered to demonstrate the clinical outcome measures for inflammation–knew circumference and temperature. Therefore we cannot draw any definitive conclusions regarding peripheral nerve blocks and any potential anti-inflammatory effects until further work is done. Second, the absence of sham blocks here can lead to observer bias. Third, the use of 20 ml of 0.75% Ropivicaine for each femoral and sciatic nerve block could have contributed towards reduced temperature and edema, given that studies have shown that Ropivicaine’s vasoactive properties cause a reduction in blood flow. Lastly, and most importantly, the reduced circumference and temperature seen may merely be the result of improved pain control and mobility. The conclusions drawn were based only on findings from postoperative days 1 to 7, with no significant differences seen between groups at a later follow-up. We therefore feel that further investigation is required before concluding that peripheral nerve blocks reduce clinical or biochemical inflammation, and if it does so, whether it actually translates into long-term patient benefit.