Olivier Choquet

Continuous peripheral nerve blocks in hospital wards after orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients.

Background:Continuous peripheral nerve block (CPNB) is the technique of choice for postoperative analgesia after painful orthopedic surgery. However, the incidence of neurologic and infectious adverse events in the postoperative period are not well established. This issue was the aim of the study. Methods:Patients scheduled to undergo orthopedic surgery performed with a CPNB were prospectively included during 1 yr in a multicenter study. Efficacy of postoperative analgesia, bacteriologic cultures of the catheter, and acute neurologic and infectious adverse events were evaluated after surgery in 1,416 patients at arrival in the postanesthesia care unit, at hour 1, and every 24 h up to day 5. Risk factors for adverse events were determined using logistic regression. Results:The median duration of CPNB was 56 h. Both general anesthesia and CPNB were performed in 73.6% of the patients. Postoperative analgesia was effective in 96.3%, but an increase in pain scores was noted at hour 24 (P = 0.01). Hypoesthesia or numbness occurred in 3% and 2.2%, respectively, and paresthesia occurred in 1.5%. Three neural lesions (0.21%) were noted after continuous femoral nerve block. Two of these patients were anesthetized during block procedure. Nerve damage completely resolved 36 h to 10 weeks later. Cultures from 28.7% of the catheters were positive. Three percent of patients had local inflammatory signs. The bacterial species most frequently found were coagulase-negative staphylococcus (61%) and gram-negative bacillus (21.6%). A Staphylococcus aureus psoas abscess (0.07%) was reported in one diabetic woman. Independent risk factors for paresthesia/dysesthesia were postoperative monitoring in intensive care, age less than 40 yr, and use of bupivacaine. Risk factors for local inflammation/infection were postoperative monitoring in intensive care, catheter duration greater than 48 h, male sex, and absence of antibiotic prophylaxis. Conclusion:CPNB is an effective technique for postoperative analgesia. Minor incidents and bacterial colonization of catheters are frequent, with no adverse clinical consequences in the large majority of cases. Major neurologic and infectious adverse events are rare.

Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation.

A computed tomographic scan was obtained in 35 patients to measure the depth and the relationship of the branches of the lumbar plexus to the posterior superior iliac spine projection and the vertebral column. In addition, we prospectively studied 80 patients scheduled for total hip arthroplasty who received a continuous psoas compartment block (CPCB) in the postoperative period. CPCB was performed after surgical procedures by using modified Winnie’s landmarks and nerve stimulation. From 5 to 8 cm of catheter was inserted. Radiographs were obtained after injection of 10 mL of contrast medium. An initial loading dose (0.4 mL/kg) of 0.2% ropivacaine was injected, followed by continuous infusion of 0.2% ropivacaine for 48 h. The depth of the lumbar plexus and the distance between the lumbar plexus and the L4 transverse process were measured. Visual analog scale values of pain at 1, 12, 24, and 48 h were obtained at rest and during mobilization. Amounts of rescue analgesia were also recorded. Sensory blockade of the principal branches of the lumbosacral plexus was noted at 1 and 24 h, as were adverse events related to the technique. There was a significant difference between men and women in depth of the lumbar plexus (median values, 85 vs 70 mm for men and women, respectively). There was a positive correlation between the body mass index and skin-lumbar plexus distances. In contrast, there was no difference regarding the distance between the transverse process of L4 and the lumbar plexus. The catheter tip lay within the psoas major muscle in 74% of the patients and between the psoas and quadratus lumborum muscles in 22%. In three patients, the catheter was improperly positioned. At 1 h, sensory blockade of the femoral, obturator, and lateral femoral cutaneous nerves was successful in, respectively, 95%, 90%, and 85% of patients. At 24 h, these rates were 88%, 88%, and 83%, respectively. During the 48-h study period, median visual analog scale values of pain were approximately 10 mm at rest and from 18 to 25 mm during physiotherapy. Five patients received 5 mg of morphine at 1 h. Five cases of unilateral epidural anesthesia were noted after the bolus injection. We conclude that CPCB with 0.2% ropivacaine allows optimal analgesia after hip arthroplasty, with few side effects and a small failure rate. Before lumbar plexus branch stimulation and catheter insertion, anesthesiologists should be aware of the L4 transverse process location and lumbar plexus depth.

Approaches to the lumbar plexus: success, risks, and outcome.

A any regional anesthesia options are available for the management of postoperative pain ssociated with major lower-limb surgery. Epidural nalgesia is commonly used, but lumbar plexus erve block may offer significant advantages in erms of quality of postoperative analgesia, increase n patient satisfaction, positive influence on surgical utcome, and patient rehabilitation compared with ntravenous opioids, and it has a lower incidence of ide effects and complications.1,2 The use of periphral nerve blocks has been recommended.3 Addiionally, interest in continuous peripheral nerve locks (CPNB) is increasing because of benefits and oncerns over interactions of anticoagulants and entral neuraxial techniques. The aim of this review s to provide an overview of the different aproaches to the lumbar plexus, as well as their risks nd indications.

Ultrasound-guided Evaluation of the Local Anesthetic Spread Parameters Required for a Rapid Surgical Popliteal Sciatic Nerve Block

Background: The ideal spread of local anesthetic (LA) solution around the sciatic nerve during a popliteal block remains unclear. We tested the hypothesis that a circumferential spread of LA and/or intraneural injection could lead to rapid surgical block. Methods: Patients (n = 100) scheduled for foot or ankle surgery underwent popliteal sciatic nerve block using nerve stimulation according to Borgeats technique and injection of ropivacaine (0.5 mL/kg). Sensory and motor blockades were assessed on the tibial nerve (TN) and common peroneal nerve (CPN) at 5, 15, and 30 mins after completion of the block and in the recovery room. A successful block was defined as a complete sensory block in TN and CPN. Changes in cross-sectional and longitudinal surfaces and diameters and the characteristics of LA spread around the nerve were noted using ultrasound. A suspected intraneural injection was defined as a 15% increase in the surface area or anteroposterior diameter of the nerve. Patients were followed up on days 1 and 7 after surgery. Results: Successful block was noted in 57% of patients at 30 mins and in 88% of patients in the recovery room. A circumferential spread of LA occurred in 47% of patients and 53% had noncircumferential spread. Complete sensory block was significantly higher in the group that had a circumferential spread (73% vs 43%, P = 0.035) only at 30 mins. In the postoperative care unit, there was no difference among the groups. Separated circumferential spreads around TN and CPN were noted in 12% of patients. All of these patients had a complete sensory and motor blockade at 15 mins. Concerning intraneural injection, only the change in the anteroposterior diameter on a 6-cm length of nerve was associated with a higher success and faster onset block at 5 (P = 0.008), 15 (P = 0.02), and 30 (P = 0.05) mins. There were no clinically detectable nerve injuries at follow-up. Conclusion: For popliteal sciatic nerve block, circumferential spread of LA, and separation of the nerve into its 2 components are associated with rapid surgical block.

A new inguinal approach for the obturator nerve block: anatomical and randomized clinical studies.

Background:Obturator nerve block is highly recommended for knee surgery in addition to a femoral nerve block. The main disadvantage of the classic approach at the pubic tubercle is low patient acceptance due to pain and discomfort. The authors hypothesized that the use of a new inguinal obturator nerve block technique would reduce pain and discomfort in patients. Methods:The inguinal approach was simulated in five fresh cadavers. Injection of latex was performed in two cadavers. The location of the needle and the extent of latex solution were analyzed. Fifty patients scheduled to undergo arthroscopic knee surgery were randomly assigned to receive obturator nerve block using either the inguinal (n = 25) or the pubic tubercle approach (n = 25). Results:In all cadavers, the needle was close to the obturator nerve branches, which were surrounded by the latex solution. In the clinical study, visual analog scale pain scores and discomfort of block placement were significantly lower in the inguinal group compared with the pubic tubercle group (P < 0.01). In the inguinal group, there was a significant decrease in block performance time (P < 0.05) and in bolus of propofol and fentanyl used for the procedure (P < 0.01). Twenty minutes after application of the block, adductor strength decrease, occurrence, and location of cutaneous distribution of the obturator nerve were not significantly different between the groups. The incidence of minor complications was significantly increased in the pubic tubercle group (P < 0.05). No major complications were observed. Conclusions:The new inguinal approach decreases patient discomfort and pain of block placement as well as the time and sedation and analgesics required for a similar quality of sensory and motor block compared with the pubic tubercle approach.

Estimation and pharmacodynamic consequences of the minimum effective anesthetic volumes for median and ulnar nerve blocks: a randomized, double-blind, controlled comparison between ultrasound and nerve stimulation guidance.

BACKGROUND:Nerve stimulation and ultrasound guidance are the most popular techniques for peripheral nerve blocks. However, the minimum effective anesthetic volume (MEAV) in selected nerves for both techniques and the consequences of decreasing the local anesthetic volume on the pharmacodynamic characteristics of nerve block remain unstudied. We designed a randomized, double-blind controlled comparison between neurostimulation and ultrasound guidance to estimate the MEAV of 1.5% mepivacaine and pharmacodynamics in median and ulnar nerve blocks. METHODS:Patients scheduled for carpal tunnel release were randomized to ultrasound guidance (UG) or neurostimulation (NS) groups. A step-up/step-down study model (Dixon method) was used to determine the MEAV with nonprobability sequential dosing based on the outcome of the previous patient. The starting dose of 1.5% mepivacaine was 13 and 11 mL for median and ulnar nerves at the humeral canal. Block success/failure resulted in a decrease/increase of 2 mL. A blinded physician assessed sensory blockade at 2-minute intervals for 20 minutes. Block onset time and duration were noted. RESULTS:The MEAV50 (SD) of the median nerve was lower in the UG group 2 (0.1) mL (95% confidence interval [CI] = [1, 96] to [2, 04]) than in the NS group 4 (3.8) mL (95% CI = [2, 4] to [5, 6]) (P = 0.017). There was no difference for the ulnar nerve between UG group 2 (0.1) mL (95% CI = [1, 96] to [2, 04]) and NS group 2.4 (0.6) mL (95% CI = [2, 1] to [2, 7]). The duration of sensory blockade was significantly correlated to local anesthetic volume, but onset time was not modified. CONCLUSION:Ultrasound guidance selectively provided a 50% reduction in the MEAV of mepivacaine 1.5% for median nerve sensory blockade in comparison with neurostimulation. Decreasing the local anesthetic volume can decrease sensory block duration but not onset time.

The ultrasound-guided transversus abdominis plane block for anterior iliac crest bone graft postoperative pain relief: a prospective descriptive study.

Background: Acute postoperative pain and nerve injuries frequently lead to neuropathic chronic pain after anterior iliac crest (AIC) bone graft. This prospective study evaluated postoperative pain relief after preoperative ultrasound-guided transversus abdominis plane (TAP) block for orthopedic surgery with an AIC bone harvest and the prevalence of pain chronicization at 18 months after surgery. Methods: Thirty-three consecutive patients scheduled for major orthopedic surgery with an AIC harvest for autologous bone graft were studied. Preoperative TAP blocks were performed under in-plane needle ultrasound guidance, anterior to the midaxillary line (15 mL ropivacaine 0.33%). The extent of sensory blockade was evaluated at 20 mins with cold and light-touch tests. Pain at the iliac crest graft site was assessed at rest by visual analog scale (VAS) scores in the postanesthetic care unit, and at 1, 6, 12, 24, and 48 hrs after surgery. Time for first request of morphine and total morphine consumption were recorded. Eighteen months after surgery, each patient was interviewed by phone about the importance and localization of pain chronicization. Results: Median VAS score was 0 (range, 0-7) at all periods of assessment. At 20 mins, 62.5% of the patients reported complete anesthesia, and 34% hypoesthesia. The sensory blockade extent ranged from T9 (T7-T11) to L1 (T11-L2) in median (range) values. At 18 months, 80% of patients did not complain about pain or discomfort at the iliac crest site; 20% reported pain chronicization at the iliac crest site (VAS scores 2-4). Five patients (26%) complained about numbness at the iliac crest area. Conclusions: Ultrasound-guided TAP block is an appropriate technique for postoperative analgesia after AIC bone harvest in orthopedic surgery.

Where should the tip of the needle be located in ultrasound-guided peripheral nerve blocks?

Purpose of review Data now exist describing the appropriate positioning of the needle tip and pattern of local anaesthetic spread after injection. The recent literature has been analysed in search of studies on the optimal procedure for common approaches centred on block efficacy, performance time, and safety. Recent findings Large peripheral nerves are surrounded by a gliding layer, the adventitia or paraneurium. Ultrasonically, a circumneural spread corresponds to adventitial extraneural injection. Nerve expansion with fascicular separation matches intraneural injection. Deliberate intraneural injection remains controversial, and is not advisable at the present time. For popliteal sciatic nerve blocks, positioning the needle in the common nerve sheath between the tibial and peroneal components and obtaining a circumneural spread surrounding both divisions predict rapid surgical anaesthesia. Using axillary and infraclavicular approaches, ultrasound-guided perivascular injection aiming at circumferential spread around the artery appears a valuable alternative to individual targeted nerve injections. For single injection interscalene block, an injection into the fascial sheath but far from the plexus proved to be as effective as an injection adjacent to the nerve structures. Fascial plane approaches are appealing alternatives for thin nerves that run between muscles and cannot be regularly visualized with the current resolution of ultrasound systems. Summary The ultrasound appearance of nerves and target injections are better understood. The specific distributions of local anaesthetic spread that predict success are significantly different from one anatomical site to another. It seems advisable to avoid intraneural injection.

Subparaneural versus circumferential extraneural injection at the bifurcation level in ultrasound-guided popliteal sciatic nerve blocks: a prospective, randomized, double-blind study.

Background The ideal spread of local anesthetic for effective, rapid, and safe sciatic nerve block is debated. We hypothesized that subparaneural ultrasound-guided injection results in faster onset and has a better success rate than extraneural circumferential spread. Methods Patients undergoing elective tibial, foot, and ankle surgery with popliteal sciatic nerve blocks were prospectively enrolled. After randomization, the needle tip position was adjusted to ensure circumferential extraneural or subparaneural spread; 0.3 mL/kg of mepivacaine 10 mg/mL was injected. Post hoc video analysis was used to group the patients according to extraneural, subparaneural, and unintentional intraepineural spread. Results There were 26 (43.3%) patients in the subparaneural group and 22 (36.7%) in the extraneural group. Block onset time was shorter in the subparaneural group than in the extraneural group (11 [3–21] minutes; mean [95% confidence interval], 11 [8.97–13.02] minutes and 17 [6–30] minutes; mean [95% confidence interval] 18.37 [14.17–22.57] minutes, respectively; P = 0.002). The duration of sensory blockade increased (397 [178–505] minutes vs 265 [113–525] minutes; P = 0.04). The success rate of the block also increased. Unintentional intraepineural injection occurred in 8% of patients (3 patients in the subparaneural group and 1 patient in the extraneural group; NS). Block onset time was shorter than for the subparaneural and extraneural groups (6 [3–12] minutes, 12 [3–21] minutes, and 18 [6–30] minutes; P = 0.01). Conclusions A subparaneural injection accelerated the onset time and increased the duration of tibial nerve sensory blockade compared with circumferential extraneural injection. With unintentional intraepineural spread, the onset time was significantly shorter than for the other groups.

Three-dimensional High-resolution Ultrasound-guided Nerve Blocks: A New Panoramic Vision of Local Anesthetic Spread and Perineural Catheter Tip Location

We report in 3 patients that high-frequency ultrasound 3-dimensional imaging enabled us to analyze anatomic variations, evaluate local anesthetic spread, and optimize a perineural catheter location by withdrawing it until its tip was appropriately positioned. This innovative technology may provide answers to different problems facing the operator performing ultrasound-guided nerve blocks. It may enhance predictability and safety aspects of peripheral nerve blocks.