Emmanuel Nouvellon

A comparison of the pharmacodynamics and pharmacokinetics of bupivacaine, ropivacaine (with epinephrine) and their equal volume mixtures with lidocaine used for femoral and sciatic nerve blocks: a double-blind randomized study.

BACKGROUND: Mixtures of lidocaine with a long-acting local anesthetic are commonly used for peripheral nerve block. Few data are available regarding the safety, efficacy, or pharmacokinetics of mixtures of local anesthetics. In the current study, we compared the effects of bupivacaine 0.5% or ropivacaine 0.75% alone or in a mixed solution of equal volumes of bupivacaine 0.5% and lidocaine 2% or ropivacaine 0.75% and lidocaine 2% for surgery after femoral-sciatic peripheral nerve block. The primary end point was onset time. METHODS: In a double-blind, randomized study, 82 adults scheduled for lower limb surgery received a sciatic (20 mL) and femoral (20 mL) peripheral nerve block with 0.5% bupivacaine (200 mg), a mixture of 0.5% bupivacaine 20 mL (100 mg) with 2% lidocaine (400 mg), 0.75% ropivacaine (300 mg) or a mixture of 0.75% ropivacaine 20 mL (150 mg) with 2% lidocaine (400 mg). Each solution contained epinephrine 1:200,000. Times to perform blocks, onset times (end of injection to complete sensory and motor block), duration of sensory and motor block, and morphine consumption via IV patient-controlled analgesia were compared. Venous blood samples of 5 mL were collected for determination of drug concentration at 0, 5, 15, 30, 45, 60, and 90 min after placement of the block. RESULTS: Patient demographics and surgical times were similar for all four groups. Sciatic onset times (sensory and motor block) were reduced by combining lidocaine with the long-acting local anesthetic. The onset of bupivacaine-lidocaine was 16 ± 9 min versus 28 ± 12 min for bupivacaine alone. The onset of ropivacaine-lidocaine was 16 ± 12 min versus 23 ± 12 for ropivacaine alone. Sensory blocks were complete for all patients within 40 min for those receiving bupivacaine–lidocaine versus 60 min for those receiving bupivacaine alone and 30 min for those receiving ropivacaine–lidocaine versus 40 min for those receiving ropivacaine alone (P < 0.05). Duration of sensory and motor block was significantly shorter in mixture groups. There was no difference among groups for visual analog scale pain scores and morphine consumption during the 48 h postoperative period, except for bupivacaine alone (median: 9 mg) versus bupivacaine–lidocaine mixture (15 mg), P < 0.01. There was no difference in the incidence of adverse events among groups. Plasma concentrations of bupivacaine and ropivacaine were higher, and remained elevated longer, in patients who received only the long-acting local anesthetic compared to patients who received the mixture of long-acting local anesthetic with lidocaine (P < 0.01). CONCLUSION: Mixtures of long-acting local anesthetics with lidocaine induced faster onset blocks of decreased duration. Whether there is a safety benefit is unclear, as the benefit of a decreased concentration of long-acting local anesthetic may be offset by the presence of a significant plasma concentration of lidocaine.

The Simplified Predictive Intubation Difficulty Score: a new weighted score for difficult airway assessment.

Background and objective Using the Intubation Difficulty Scale (IDS) more than 5 as a standardized definition of difficult intubation, we propose a new score to predict difficult intubation: the Simplified Predictive Intubation Difficulty Score (SPIDS). Methods We prospectively studied 1024 patients scheduled for elective surgery under general anaesthesia. Using bivariate and multivariable analysis, we established risk factors of difficult intubation. Then, we assigned point values to each of the adjusted risk factors, their sum composing the SPIDS. We assessed its predictive accuracy using sensitivity, specificity, positive (PPV) and negative predictive values (NPV), and the area under the receiver operating characteristic (ROC) curve (AUC), and compared it with the corresponding nonweighted score. The optimal predictive level of the SPIDS was determined using ROC curve analysis. Results We found five adjusted risk factors for IDS more than 5: pathological conditions associated with difficult intubation (malformation of the face, acromegaly, cervical rheumatism, tumours of the airway, and diabetes mellitus), mouth opening less than 3.5 cm, a ratio of patients height to thyromental distance 25 at least, head and neck movement less than 80°, and Mallampati 2 at least. Sensitivity, specificity, PPV and NPV of the SPIDS were 65, 76, 14 and 97%, respectively. AUC of the SPIDS and the nonweighted score (obtained previously using a stepwise logistic regression) were respectively 0.78 [95% confidence interval (CI) 0.72–0.84] and 0.69 (95% CI 0.64–0.73). The threshold for an optimal predictive level of the SPIDS was above 10 of 55. Conclusion The SPIDS seems easy to perform, and by weighting risk factors of difficult intubation, it could help anaesthesiologists to plan a difficult airway management strategy. A value of SPIDS strictly above 10 could encourage the anaesthesiologists to plan for the beginning of the anaesthetic induction with ‘alternative’ airway devices ready in the operating theatre.

American Society of Anesthesiologists' physical status system: a multicentre Francophone study to analyse reasons for classification disagreement.

Context Variability of American Society of Anesthesiologists’ (ASA) physical status scores attributed to the same patient by multiple physicians has been reported in several studies. In these studies, the population was limited and diseases that induced disagreement were not analysed. Objectives To evaluate the reproducibility of ASA physical status assessment on a large population, as used in current practice before scheduled surgery. Design Multicentre, randomised, blinded cross-over observational study. Methods During a 2-week period in nine institutions, ASA physical status and details of assessment performed routinely by anaesthesiologists for patients who underwent elective surgery were recorded. Records were blinded (including ASA physical status) by an independent statistical division and returned randomly to one of the nine centres for reassessment by accredited specialist anaesthesiologists. Main outcome measures The level of agreement between the two measurements of the ASA physical status was calculated by using the weighted Kappa coefficient. Results During the study period, 1554 anaesthesia records were collected and 197 were excluded from analysis because of missing data. After the initial evaluation, the distribution of ASA physical status grades was as follows: ASA 1, 571; ASA 2, 591; ASA 3, 177; and ASA 4, 18. After the final evaluation, the distribution of ASA grades was as follows: ASA 1, 583; ASA 2, 520; ASA 3, 223; and ASA 4, 31. Two per cent of the patients had an underestimation of their physical status. The degree of agreement between the two measures evaluated by the weighted Kappa coefficient was 0.53 (0.49–0.56). No difference was observed between public and private institutions. Patients with co-existing diseases, obesity, allergy, sleep apnoea, obstructive lung disease, renal insufficiency and hypertension were least likely to have been graded correctly. Conclusion The degree of agreement between two measures of the ASA physical status grade is moderate and influenced by staff characteristics and the complexity of diseases.

Regional Anesthesia and Eye Surgery

THE vast majority of ophthalmic surgeries are performed under regional anesthesia only. However, its use is also described in association with general anesthesia for pediatric cases and for postoperative analgesia. Eye blocks have long been limited to retrobulbar anesthesia (RBA) as performed by surgeons. Surgical technique changes and research on improving patient safety during eye blocks has resulted in the development of alternative techniques, such as peribulbar anesthesia (PBA), followed by low-volume sub-Tenon block (STA) or topical anesthesia (TA). In this review, we present the general requirements necessary for an eye block and then briefly describe each technique, discussing their respective advantages and inconveniences. Although cataract surgery is the most frequent ophthalmic surgical procedure and a large number of articles we cite refer to studies concerning this procedure, implications to regional anesthesia are not limited to cataract surgery; much of the data we review can be extrapolated and reinterpreted for other ophthalmic applications.

Anaesthesia for Cataract Surgery

Cataract surgery is the most frequent surgical procedure requiring anaesthesia in developed countries. It is performed mainly in elderly patients, who present with many coexisting diseases that induce subsequent hazards from general anaesthesia. Cataract anaesthesia is performed following various techniques of regional anaesthesia, which are detailed in this review. Needle block carries a low but real risk of complications, mainly because of needle misplacement. Correct teaching and training are mandatory to prevent complications. The main patient risk factor for inadvertent globe perforation is the presence of a myopic staphyloma. Retrobulbar block has been progressively phased out and replaced by peribulbar block, sub-Tenon’s block (STB) or topical anaesthesia (TA). The requirement for very deep block with total akinesia has greatly decreased with the use of phacoemulsification for cataract surgery, allowing for use of TA or low-volume STB. However, non-akinesia techniques may give rise to impaired surgical conditions, which have the potential to result in surgical complications. A surgical approach to accessing sub-Tenon’s space avoids needle block, but does not totally prevent complications. When deep anaesthesia is required, low-volume STB, performed using either the needle technique or a surgical approach, appears to be the technique of choice in terms of efficacy. Increasing the anaesthetic volume provides reproducible akinesia. Various local anaesthetics may be used, depending on their availability and respective properties. The most useful adjuvant to local anaesthetic is hyaluronidase.

Ophthalmic regional anesthesia: medial canthus episcleral (sub-tenon) single injection block.

BackgroundThe purpose of this study was to evaluate the efficacy and safety of episcleral single-injection anesthesia in a large number of patients. MethodsOver a period of 5 yr, in four institutions, anesthesiologists involved in this prospective study completed a standardized form to evaluate single-injection medial canthus high-volume episcleral anesthesia. The success rate of the block was rated according to an akinesia score. The study parameters included demographic data, surgical procedure, and anesthetic management. All patients were followed up at least until postoperative day 1, and all complications, pain, and discomfort were noted. Statistical analysis was done to assess the risk factors for complications. ResultsA total of 2,031 patients were included in the study. The most frequent surgical procedures performed were phacoemulsification and posterior chamber artificial lens implantation (91.0%). A total of 66 complications (3.3%) occurred in 60 patients. One patient had a retrobulbar hemorrhage, and 59 had one or two more minor incidents or pain/discomfort with the procedure. The complications consisted of subconjunctival hematoma (1.3%), ocular hypertonia (0.4%), and chemosis (0.30%). Statistical analysis revealed that inexperience in the technique represented a risk factor for complications. ConclusionsThis is the first survey of a large experience in episcleral single-injection anesthesia, a form of anesthesia that does not preclude sharp-needle complications and does require training. Only one complication occurred among 2,031 patients; however, a larger number of patients is needed to definitively evaluate the safety of episcleral single-injection anesthesia.

Regional anesthesia for eye surgery

p r m s o g o o d a n n w t s t n t n c a c o f M c o i a o p c e h p a t phthalmic surgery is the most frequent surgical procedure requiring anesthesia in develped countries. Nearly 2 million patients undergo ataract surgery each year in the United States.1 ost procedures are performed under regional ansthesia. Eye blocks have long been limited to retobulbar anesthesia performed by the surgeon with nly monitored anesthesia care or no anesthesiolgist assistance at all. Anesthesiologists are now ncreasingly involved in ophthalmic regional aneshesia. After changes in surgical practice because of he widespread use of the phacoemulsification echnique, requests from the surgeon for total akiesia and lowered intraocular pressure have dereased. In the meantime, complications of the conentional retrobulbar anesthesia (RBA) technique ave been extensively described, and the need for reater safety during eye block has been emphaized. This has resulted in the development of sevral emerging techniques intended to improve afety, even at the price of imperfect akinesia. These echniques may be useful for anterior segment surery, especially cataract surgery. However, some urgeons still express a need for more efficient lock, providing total globe akinesia and anesthesia f the globe for some surgical procedures (eg, poserior segment) and for some individual patients. A ood knowledge of anatomy and of the various echniques will allow the anesthesiologist to choose he best block technique for each situation. This eview will focus on the relevant anatomy, the lassical (retro and peribulbar) needle block techiques along with their efficacy and complications, he emerging techniques and their relative interest nd drawbacks, the choice of local anesthetics and

Parasacral approach to block the sciatic nerve: A 400-case survey

Background and Objectives: Parasacral sciatic nerve block has been shown to be easy to perform, but studies reported to date involve a total of only 155 patients. The aim of this study was to assess the efficacy of parasacral sciatic nerve block in a larger group of patients. Methods: Four hundred consecutive parasacral blocks were evaluated prospectively. The level of expertise of the practitioner, the time to perform the block, the lowest current intensity of nerve stimulation, the injected volume, the onset time, the success or failure of the block, and complications were recorded. Results: The time required to perform the block was 7 ± 5 minutes. The lowest stimulation-current intensity was 0.4 ± 0.1 mA, and the injected volume was 27 ± 4 mL. The onset time was 13 ± 7 minutes for both motor and sensory block in all nerve distributions. The success rate was 94% (376 of 400 cases). Nine supplemental injections were performed successfully, thus increasing the success rate to 96%. General anesthesia or heavy sedation was performed in 15 cases (3.8%). There was no difference in failure rate between more experienced and less experienced anesthesiologists. Conclusions: In this prospective 400-case study, we confirmed previous findings that the parasacral approach is effective, easy to perform, and easy to teach, even when performed by relatively inexperienced physicians. The parasacral approach is, therefore, an effective alternative to other approaches of sciatic nerve blockade.

Does the type of fluid affect rapidity of shock reversal in an anaesthetized-piglet model of near-fatal controlled haemorrhage? A randomized study

BACKGROUND The optimal resuscitation fluid for the early treatment of severe bleeding patients remains highly debated. The objective of this experimental study was to compare the rapidity of shock reversal with lactated Ringer (LR) or hydroxyethyl starch (HES) 130/0.4 at the early phase of controlled haemorrhagic shock. To assess the influence of vascular permeability in this model, we measured plasma vascular endothelial growth factor (VEGF) levels during the experiment. METHODS Thirty-six anaesthetized and mechanically ventilated piglets were bled (<30 ml kg(-1)) to hold mean arterial pressure (MAP) at 40 mm Hg for more than 30 min and were resuscitated in two randomized groups: LR (n=14) or HES (n=14) at 1 ml kg(-1) min(-1) until MAP reached its baseline value of ±10%. MAP was maintained at its baseline value for 1 h. The time and fluid volume necessary to restore the baseline MAP value were measured. RESULTS The time to restore the baseline MAP value of ±10% was significantly lower in the HES group (P<0.001). During the initial resuscitation phase, the infused volume was 279 (119) ml in the HES group and 1011 (561) ml in the LR group (P<0.0001). During the stabilization phase, the infused volume was 119 (124) ml in the HES group and 541 (506) ml in the LR group. Biological data and plasma VEGF levels were similar between the groups. CONCLUSIONS Restoration of MAP was four times faster with HES than with LR in the early phase of controlled haemorrhagic shock. However, there was no evidence of increased vascular permeability.

Caruncle single injection episcleral (Sub-tenon) anesthesia for cataract surgery: mepivacaine versus a lidocaine-bupivacaine mixture.

UNLABELLED We compared the quality of anesthesia provided by mepivacaine 2% or a mixture of lidocaine 2%-bupivacaine 0.5%, both with hyaluronidase, in caruncle single-injection episcleral (sub-Tenon) anesthesia. Sixty patients undergoing cataract surgery were included in this randomized, double-blinded study. The time to the onset of blockade, maximal akinesia, need for supplemental injection, and time to recovery were recorded. With mepivacaine, the time to onset was slightly shorter, and the akinesia score higher, than with the mixture. Although statistically significant, these differences are small. With mepivacaine, the time to recovery was shorter. We conclude that the reproducible short duration of the block may be an advantage in outpatient surgery. IMPLICATIONS We compared the classic mixture of lidocaine 2% plus bupivacaine 0.5% to mepivacaine 2% for caruncle episcleral (sub-Tenon) anesthesia for cataract surgery. Mepivacaine provided a more efficient block with a quicker onset and a quicker recovery. However, these differences were very small and were of little clinical interest.