Ultrasound-Guided Selective Versus Conventional Block of the Medial Brachial Cutaneous and the Intercostobrachial Nerves: A Randomized Clinical Trial.

BACKGROUND AND OBJECTIVES: For superficial surgery of anteromedial and posteromedial surfaces of the upper arm, the medial brachial cutaneous nerve (MBCN) and the intercostobrachial nerve (ICBN) must be selectively blocked, in addition to an axillary brachial plexus block. We compared efficacy of ultrasound-guided (USG) versus conventional block of the MBCN and the ICBN. METHODS: Eighty-four patients, undergoing upper limb surgery, were randomized to receive either USG (n = 42) or conventional (n = 42) block of the MBCN and the ICBN with 1% mepivacaine. Sensory block was evaluated using light-touch on the upper and lower half of the anteromedial and posteromedial surfaces of the upper arm at 5, 10, 15, 20 minutes after nerve blocks. The primary outcome was the proportion of patients who had no sensation in all 4 regions innervated by the MBCN and the ICBN at 20 minutes. Secondary outcomes were onset time of complete anesthesia, volume of local anesthetic, tourniquet tolerance, and quality of ultrasound images. RESULTS: In the USG group, 37 patients (88%) had no sensation at 20 minutes in any of the 4 areas tested versus 8 patients (19%) in the conventional group (P < 0.001). When complete anesthesia was obtained, it occurred within 10 minutes in more than 90% of patients, in both groups. Mean total volumes of local anesthetic used for blocking the MBCN and the ICBN were similar in the 2 groups. Ultrasound images were of good quality in only 20 (47.6%) of 42 patients. Forty-one patients (97.6%) who received USG block were comfortable with the tourniquet versus 16 patients (38.1%) in the conventional group (P < 0.001). CONCLUSIONS: Ultrasound guidance improved the efficacy of the MBCN and ICBN blocks. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02940847.

Guidelines on the use of ultrasound guidance for vascular access.

Insertion of vascular access is a common procedure with potential for iatrogenic events, some of which can be serious. The spread of ultrasound scanners in operating rooms, intensive care units and emergency departments has made ultrasound-guided catheterisation possible. The first guidelines were published a decade ago but are not always followed in France. The French Society of Anaesthesia and Intensive Care has decided to adopt a position on this issue through its Guidelines Committee in order to propose a limited number of simple guidelines. The method used was the GRADE(®) method using the most recently published meta-analyses as the source of references. The level of evidence found ranged from low to high and all the positive aspects associated with ultrasound guidance, i.e. fewer traumatic complications at puncture, probably or definitely outweigh the potential adverse consequences regardless of whether an adult or child is involved and regardless of the site of insertion.

Ultrasound guidance of needle tip position for femoral nerve blockade: an observational study.

BACKGROUND: The femoral nerve lies in the ilio-fascial space in a groove formed by the iliac and psoas muscles (GIPM) posteriorly, and overlaid by the iliac fascia. Recommendations for needle insertion for femoral blockade using ultrasound imaging are to insert the needle tip behind the iliac fascia at the lateral side of the femoral nerve, but this part of the nerve is poorly visualised in some patients. A more accurate location of the lateral part of the femoral nerve might be achieved by identifying the GIPM and its lateral segment. OBJECTIVES: The objectives of this study are to determine the frequency of ultrasound visibility of the lateral part of the femoral nerve and GIPM, and to note the motor response to electrostimulation of the nerve and the spread of local anaesthetic when positioning the needle tip at the lateral segment of the GIPM. DESIGN: A prospective observational (case series) study. SETTING: Department of Anaesthesiology of a University Hospital. PATIENTS: Inpatients undergoing hip or knee surgery scheduled to have femoral nerve blockade were eligible to participate. INTERVENTIONS: The ultrasound probe was positioned in the inguinal region, and direct ultrasound identification of the femoral nerve, lying on the GIPM behind the iliac fascia, was obtained. A stimulating needle, inserted in-plane and advanced lateral to medial was directed towards the femoral nerve until it made contact with the target structure defined as the lateral segment of the GIPM. MAIN OUTCOME MEASURE: Ultrasound identification of the lateral part of the femoral nerve and GIPM. RESULTS: An image compatible with the lateral part of the femoral nerve was observed in 91 out of 100 patients. In the remaining nine patients, when the lateral part of the femoral nerve was not seen, GIPM could be visualised in five (55%) patients. The iliac fascia and GIPM were clearly visualised in 68 and 85 patients respectively. In 85 cases when the needle tip was placed at the lateral segment of GIPM, a quadriceps femoris muscle motor response was obtained, and the distribution of the anaesthetic solution was observed behind the iliac fascia in all patients. In two patients, only the iliac fascia was identified, and in the two patients, none of these structures was correctly visualised. CONCLUSION: The GIPM was seen in the majority undergoing ultrasound-guided femoral nerve blockade, even when the lateral part of the femoral nerve was not visualised. Using the lateral segment of GIPM as a target for needle tip location in an in-plane lateral to medial approach of the femoral nerve deserves further investigation.

Ultrasound guidance, a win-win approach to peripheral nerve blockade.

PURPOSE OF REVIEW: The objective of the current review is to examine the likelihood of improved safety in peripheral nerve blockade attributable to ultrasound guidance. RECENT FINDINGS: With ultrasound guidance, a 10-fold reduction in the incidence of local anesthetic systemic toxicity as well as a tendency toward less long-term neuropathies are shown. SUMMARY: Ultrasound is clearly superior to other techniques with the aim of achieving maximum efficacy with minimum risk: a win-win approach.

Case report: pudendal nerve injury after a sciatic nerve block by the posterior approach.

We report a pudendal nerve injury that developed after a posterior approach to the sciatic nerve. A classical Labat's posterior sciatic nerve block on the right side was performed using an insulated needle and a nerve stimulator set at an initial current of 2 mA, 2 Hz frequency, and 0.1 ms duration. Painful paresthesia radiating to the right side of the patient's penis and right leg was experienced shortly after needle insertion. The needle was immediately withdrawn and redirected laterally. Motor responses for the common peroneal and tibial components of the sciatic nerve were elicited at 0.48 mA in both cases and a 10-mL bolus of mepivacaine 1.5% was injected onto each component. The sciatic nerve block was combined with a femoral nerve block to facilitate a knee arthroscopy. The trauma resulted in erectile dysfunction and partial loss of penile sensation as well as evidence of injury to the sciatic nerve itself. Symptoms and clinical signs of pudendal nerve injury lasted 7 months. This is the first time that sexual dysfunction as a result of a unilateral pudendal nerve injury that occurred after a posterior sciatic nerve block has been reported.

Nerve blocks at the wrist for carpal tunnel release revisited: the use of sensory-nerve and motor-nerve stimulation techniques.

BACKGROUND AND OBJECTIVES: Because the median nerve at the wrist has mainly sensory endings, the aim of this study was to assess the response of the median nerve to nerve stimulation at the wrist and to evaluate the quality of median nerve block. A control group of patients who received blinded injections was analyzed and compared post hoc. METHODS: One hundred and eleven patients scheduled for ambulatory endoscopic carpal-tunnel release performed under median and ulnar nerve blocks at the wrist were prospectively studied. The blocks were performed with a nerve stimulator. Nerve-stimulation techniques were explained to the patient before the block was performed. The patient was trained to inform the anesthetist of their perception of an electrical paresthesia that was synchronized to the nerve stimulator. The anesthetist recorded the first response of the patient to nerve stimulation: sensory (S), sensory-motor (SM), or motor response (M). When the minimal stimulating current was obtained, an equal volume of 4 mL of 1.5% mepivacaine was injected on median and ulnar nerves. If necessary, a lateral subcutaneous injection of 2 mL of 1.5% mepivacaine was administered at the wrist crease in the musculocutaneous nerve area. Thirty-five patients who received blinded local anesthetics injections were included post hoc. Quality of anesthesia was compared between groups. RESULTS: Responses included 89 S (80.2%), 18 SM (16.2%), and 4 M (3.71%). No differences occurred in time to perform the block, minimal current intensity, and efficacy. More punctures were necessary in the M group compared with the S group and the control group (P < .05). The onset time of sensory blocks increased significantly in control-group patients (P < .05), but the duration of the nerve-block procedure decreased in comparison with the M group. Respectively, 10% and 20% of patients experienced mild or severe pain in the nerve-stimulation group and control group. At 20 minutes, the block was complete for the median and ulnar nerves in 96.4% and 85% of the nerve-stimulation patients and control patients (P < .05). Two patients in the control group experienced painful mechanical paresthesia. Neither permanent nor transient nerve injuries were observed during or after the nerve block or surgery. CONCLUSION: This study describes how infrequently an initial motor response is identified when a nerve stimulator is used on the median nerve at the wrist. A very high success rate of median and ulnar nerve block at the wrist is obtained by use of sensory or sensory-motor-nerve stimulation and less than 10 mL of anesthetic solution.

Adding a selective obturator nerve block to the parasacral sciatic nerve block: an evaluation.

Our aim was to objectively evaluate the efficacy of obturator nerve anesthesia after a parasacral block. Patients scheduled for knee surgery had a baseline adductor strength evaluation. After a parasacral block with 30 mL 0.75% ropivacaine, sensory deficit in the sciatic distribution (temperature discrimination) and adductor strength were assessed at 5-min intervals. Patients with an incomplete sensory block (defined as a temperature discrimination score of less than 2 in the 3 cutaneous distributions of the sciatic nerve tested) 30 min after the parasacral block were excluded from the study. Subsequently, a selective obturator block was performed with 7 mL 0.75% ropivacaine and adductor strength was reassessed at 5 min intervals for 15 min. Finally, a femoral block was performed using 10 mL 0.75% ropivacaine. Patient discomfort level during each block was assessed using a visual analog scale (VAS). Thirty-one patients completed the study. Five patients were excluded as a result of inadequate sensory block in the sciatic distribution 30 min after the parasacral block (success rate of 89%). Thirty min after the parasacral block, adductor strength decreased by 11.3% +/- 7% compared with baseline (85 +/- 24 versus 97 +/- 28 mm Hg, P = 0.002). Fifteen min after the obturator nerve block, adductor muscle strength decreased by an additional 69% +/- 7% (16.6 +/- 15 versus 85 +/- 24 mm Hg, P < 0.0001). VAS scores were similar for all blocks (26 +/- 19, 28 +/- 24, and 27 +/- 19 mm for parasacral, obturator, and femoral respectively). Four parasacral blocks were simulated in 2 fresh cadavers using 30 mL of colored latex solution. The spread of the die in relation to the obturator nerve was assessed. Injection of 30 mL colored latex into cadavers resulted in spread of the injectate restricted to the sacral plexus. These findings demonstrate the unreliability of parasacral block to achieve anesthesia of the obturator nerve. A selective obturator block should be considered in the clinical setting when this is desirable.

Postoperative analgesia by femoral nerve block with ropivacaine 0.2% after major knee surgery: continuous versus patient-controlled techniques.

BACKGROUND AND OBJECTIVES: This prospective study compared the efficacy and adverse effects after knee surgery of ropivacaine 0.2% administered as patient-controlled femoral analgesia (PCFA), as a continuous femoral infusion (Inf), or as both (PCFA+Inf). METHODS: Before general anesthesia, 140 adults scheduled to undergo major knee surgery received a sciatic/fascia iliaca nerve block with 0.75% ropivacaine (40 mL). After surgery, they were randomly assigned to receive, through the femoral catheter, an infusion of 0.2% ropivacaine administered as PCFA (boluses of 10 mL with a lockout time of 60 minutes), Inf (10 mL/h), or PCFA + Inf (5 mL/h plus boluses of 5 mL with a lockout time of 60 minutes). Pain was assessed at rest, on mobilization, and during physiotherapy using a visual analog scale (VAS). Additional use of intravenous (IV) analgesics was noted. RESULTS: Patients in all 3 groups experienced similar pain relief at rest, on mobilization, and after physiotherapy (P >.05). Additional use of analgesics and overall patient satisfaction (excellent or good in 80% of cases) were also similar in all groups. However, total postoperative ropivacaine consumption was lower in the PCFA group, 150 mL/48 h (90.5 to 210); than in the Inf group, 480 mL/48 h (478 to 480); and the PCFA + Inf group, 310 mL/48 h (280 to 340) (P <.05). Adverse events were similar in all 3 groups (hypotension, vomiting, insomnia). No paresthesia or motor block were observed. CONCLUSION: All 3 strategies provided effective pain relief. PCFA resulted in a lower consumption of ropivacaine (toxic and financial impact). PCFA + Inf does not improve postoperative analgesia.

An evaluation of the cutaneous distribution after obturator nerve block.

UNLABELLED: In 1973, Winnie et al. introduced the inguinal paravascular three-in-one block, which allegedly provides anesthesia of three nerves--the femoral, lateral cutaneous femoral, and obturator nerves--with a single injection. This concept was undisputed until the success of the obturator nerve block was reassessed by using evidence of adductor weakness rather than cutaneous sensory blockade, the latter being variable in its distribution and often absent. We performed this study, therefore, to evaluate the area of sensory loss produced by direct injection of local anesthetic around the obturator nerve. A selective obturator nerve block with 7 mL of 0.75% ropivacaine was performed in 30 patients scheduled for knee surgery. Sensory deficit and adductor strength were evaluated for 30 min by using sensory tests (cold and light-touch perception) and the pressure generated by the patient's squeezing a blood pressure cuff placed between the knees. Subsequently, a three-in-one block was performed, and the sensory deficit was reassessed. The obturator nerve block was successful in 100% of cases. The strength of adductors decreased by 77% +/- 17% (mean +/- SD). In 17 patients (57%), there was no cutaneous contribution of the obturator nerve. The remaining 7 patients (23%) had an area of hypoesthesia (cold sensation was blunt but still present) on the superior part of the popliteal fossa, and the other 6 (20%) had sensory deficit located at the medial aspect of the thigh. The three-in-one block resulted in blockade of the lateral aspect of the thigh in 87% of cases, whereas the anteromedial aspect was always anesthetized. By use of magnetic resonance imaging in eight volunteers, we demonstrated that the obturator nerve has already divided into its two branches at the site of local anesthetic injection. However, the injection of blue dye after having simulated the technique in five cadavers showed that the fluid regularly spread to both branches. We conclude that after three-in-one block, a femoral nerve block may have been assessed as an obturator nerve block in 100% of cases when testing the cutaneous distribution of the obturator nerve on the medial aspect of the thigh. IMPLICATIONS: Previous studies reporting an incidence of obturator nerve block after three-in-one block may have mistaken a femoral nerve block for an obturator nerve block in 100% of cases when the cutaneous distribution of the obturator nerve was assessed on the medial aspect of the thigh. The only way to effectively evaluate obturator nerve function is to assess adductor strength.