Ultrasound-guided Popliteal Sciatic Nerve Block Research Articles

The application of surgeon-administered ultrasound-guided popliteal sciatic nerve block in foot and ankle injuries

Introduction Ultrasound-guided popliteal sciatic nerve block has been described as a safe and consistent form of regional anesthesia for foot and ankle surgery. Little studies have been performed to prove the effectiveness of surgeon self-administered regional anesthesia for foot and ankle injury requiring an operation. This study aimed to assess the applicability and safety in surgeon-administered ultrasound-guided popliteal sciatic nerve block in providing anesthesia for foot and ankle fracture. Material and Methods Patients with foot and ankle injury who underwent operation under surgeon-administered ultrasound-guided popliteal sciatic nerve block were evaluated in this retrospective study. A total of 7 patients (3 females and 4 males) with a mean age of 46) were evaluated by the diagnosis, side of injury, comorbidities in American Society of Anesthesiologists Classification (ASA), duration of operation, blood loss, pain control in visual analog scale (VAS) intra-operatively, degree of motor blockage, post-operative pain control and hospital length of stay. Result Average age of the study population was 46. Of all the patients, two of them were of ASA I four of them were of ASA II and one of them was of ASA III. Complete sensory and motor blockages were achieved for all patients. Average operative time was 117 min. Average blood loss was 16.4 mL. Average post-operative inpatient stay was 3.57 days. There was no regional anesthesia-related complication arising from the procedure. Conclusion Surgeon-administered popliteal sciatic nerve block is a safe procedure and can provide excellent pain control throughout the operation according to our experience. Foot and ankle fracture fixation can be performed by orthopedic surgeons under this technique.

Intravenous injection of dexamethasone is non-inferior to perineural administration for popliteal sciatic nerve and saphenous nerve blocks: A randomized, controlled, triple-blind study

BackgroundThe aim of this study was to assess whether intravenous dexamethasone was noninferior to perineural dexamethasone as an adjuvant to ropivacaine for a combination of saphenous and sciatic nerve blocks in patients undergoing foot and ankle surgery. MethodsThis was a prospective, blinded, randomized noninferiority study. Seventy-five patients, aged 18–75 years, with an American Society of Anesthesiologists (ASA) physical status I-III who underwent foot and ankle surgery were involved. Patients scheduled for ultrasound-guided popliteal sciatic nerve block and saphenous nerve block were randomized to receive 0.375% ropivacaine with 7.5 mg of dexamethasone perineurally (Dex-PN), 10 mg of dexamethasone intravenously (Dex-IV) or neither (Placebo). The primary outcome was the duration of analgesia. The major secondary outcomes were the composite pain intensity and opioid consumption score at 0–48 h intervals after anesthesia. ResultsThe mean analgesic duration was 26.2 h in the Dex-IV group and 27.9 h in the Dex-PN group (duration difference, −1.7; 95% CI, −3.8 to 0.43; P = 0.117), and both durations were significantly longer than that in the placebo group (17.6 h, P < 0.001). Conditions for establishing non-inferiority were met. ConclusionsOur findings indicate that a single 10-mg intravenous dose of dexamethasone was noninferior to the combined dose of ropivacaine plus deaxmethasone in terms of duration of analgesia for foot and ankle surgery.

Endovascular revascularization of critical limb ischemia: the role of ultrasound-guided popliteal sciatic nerve block for the procedural pain management.

To evaluate the impact of the ultrasound-guided popliteal sciatic nerve block (PSNB) for pain management during endovascular treatment of chronic limb-threatening ischemia (CLTI). From November 2020 to January 2022, 111 CLTI patients that underwent endovascular procedures were prospectively enrolled in this prospective single-arm interventional study. Ultrasound-guided PSNB was used for procedural pain control. Pain intensity was evaluated throughout the procedure (baseline, 10min after the block, pain peak, and at the end of the procedure) with the visual analog scale (VAS). Forty-six patients underwent above-the-knee revascularization (ATK), 20/111 below-the-knee (BTK) revascularization, 20/111 to both ATK and BTK revascularization. In 25 cases, no endovascular option was feasible at diagnostic angiography. The PSNB was effective in 96% of patients, with no need for further pain management with a statistically significant reduction (p < 0.0001) in the mean value of the VAS from 7.86 ± 1.81 (pre-procedural) to 2.04 ± 2.20 after 10min from the block and up to 0.74 ± 1.43 at the end of the procedure (mean time 43min). Only 1 complication related to the popliteal sciatic nerve block was registered (a temporary foot drop, completely resolved within 48h). The time necessary to perform the block ranged between 4 and 10min. Ultrasound-guided PSNB is a feasible and effective method to manage patients with rest pain and increase comfort and compliance during endovascular procedures. An ultrasound-guided popliteal sciatic nerve block is a safe, feasible, and effective technique to manage pain during endovascular treatment of chronic limb-threatening ischemia, especially in frail patients with multiple comorbidities who are poor candidates for deep sedoanalgesia or general anesthesia. Endovascular treatment of CTLI may require long revascularization sessions in patients with high levels of pain at rest, which could be exacerbated during the revascularization procedure. The PSNB is routinely used for anesthesia and analgesia during foot and ankle surgery, but the experience with lower limb revascularization procedures is very limited and not included in any international guideline. Ultrasound-guided PSNB is a feasible and effective regional anesthesia technique to relieve procedural and resting pain. Because of its safety and availability, every interventional radiologist should know how to perform this type of loco-regional anesthesia.

Ultrasound-Guided Popliteal Sciatic Nerve Block: A Minimally Invasive Method for Pain Control During Endovascular Treatment of Critical Limb Ischemia

PurposeTo evaluate the safety and effectiveness of ultrasound-guided popliteal sciatic nerve block (PSNB) for pain control in endovascular treatment of critical limb ischemia (CLI). Materials and MethodsThis retrospective study included 252 patients who underwent endovascular treatment for CLI between January 2020 and August 2022. Of these, 69 patients underwent PSNB, whereas moderate procedural sedation and analgesia was delivered in 183 patients. Pain scores were assessed using the visual analog scale (VAS) before and during the intervention. Technical and clinical success of PSNB, duration of the procedure, time to onset of nerve block, time for block resolution, and adverse events were recorded. Patient and operator satisfaction were assessed using the Likert scale. ResultsAll PSNB procedures were technically and clinically successful, and the mean procedural duration of PSNB was 5.0 minutes ± 0.8 (range, 4–7 minutes). Prolonged effect of PSNB was observed in 3 patients, which resolved within 24 hours. No adverse events were encountered. Median VAS score was significantly lower in the PSNB group than in the moderate procedural sedation and analgesia group during endovascular treatment (0 [range, 0–2] vs 3 [range, 0–7]; P < .001). Patient satisfaction was comparable (“very satisfied” in 66 [95.7%] vs 161 [88.0%]; P = .069). However, operator satisfaction was significantly higher in the PSNB group (“very satisfied” in 69 [100%] vs 161 [88.0%]; P = .003). ConclusionsPSNB is safe and effective for pain control during endovascular treatment of CLI. Low adverse event rates with high patient and operator satisfaction make PSNB a reasonable alternative for high-risk patients.

A Combination of Ultrasound-guided Popliteal Sciatic Nerve Block and Adductor Canal Block as a Sole Anaesthetic Technique for below Knee Amputation in High-risk Patients: A Case Series

Below-knee amputation in high-risk patients is associated with significant mortality and morbidity. Spinal anaesthesia is linked to an increased incidence of hypotension and bradycardia, and it is relatively contraindicated in patients with coagulation abnormalities. General anaesthesia is used as an alternative when spinal anaesthesia is contraindicated, but it is associated with a considerable increase in perioperative morbidity and the need for postoperative ventilatory support and Intensive Care Unit (ICU) care. A combination of sciatic nerve block and femoral block has been employed for below-knee surgeries as it provides complete anaesthesia below the knee. Adductor canal block, compared to femoral nerve block, is motor-sparing and, when combined with popliteal sciatic nerve block, offers complete anaesthesia below the knee. Below-knee amputation requires complete motor and sensory blockage, making regional block for below-knee amputation more challenging for the anaesthesiologist. Present case series is of five cases of below-knee amputation performed under a combination of ultrasound-guided popliteal sciatic nerve block and adductor canal block. Ultrasound-guided popliteal sciatic nerve block was administered with a combination of 10 mL of bupivacaine 0.5% and 5 mL of lignocaine 2% with adrenaline (1:200,000) diluted with 5 mL of distilled water to a total volume of 20 mL. Ultrasound-guided adductor canal block was performed with 8 mL of bupivacaine 0.5% and 4 mL of lignocaine 2% with adrenaline (1:200,000), diluted with 4 mL of distilled water to a total volume of 16 mL. All patients achieved adequate surgical anaesthesia, and none experienced any anaesthesia-related complications.

Ultrasound-guided popliteal sciatic nerve block using bupivacaine alone or combined with magnesium sulfate for diabetic foot surgeries

Ultrasound-guided popliteal sciatic nerve block using bupivacaine alone or combined with magnesium sulfate for diabetic foot surgeries

Impact of self-coiling catheters for continuous popliteal sciatic block on postoperative pain level and dislocation rate: a randomized controlled trial

BackgroundDislocation of catheters within the tissue is a challenge in continuous regional anesthesia. A novel self-coiling catheter design is available and has demonstrated a lower dislocation rate in a cadaver model. The dislocation rate and effect on postoperative pain of these catheters in vivo has yet to be determined and were the subjects of this investigation.MethodsAfter ethics committee approval 140 patients undergoing elective distal lower limb surgery were enrolled in this prospective randomized controlled trial. Preoperatively, patients were randomly assigned and received either the conventional (n = 70) or self-coiling catheter (n = 70) for ultrasound-guided popliteal sciatic nerve block in short axis view and by the in-plane approach from lateral to medial. The primary outcome was pain intensity after surgery and on the following three postoperative days. Secondary outcomes investigated were dislocation rate in situ determined by sonography, catheter movement visible from outside, opioid consumption as well as leakage at the puncture site.ResultsAll catheters were successfully inserted. The study population of self-coiling catheters had significantly lower mean numeric rating scale values than the reference cohort on the first (p = 0.01) and second postoperative days (p < 0.01). Sonographic evaluation demonstrated, 42 standard catheters (60%) and 10 self-coiling catheters (14.3%) were dislocated in situ within the first three postoperative days. The externally visible movement of the catheters at insertion site did not differ significantly between groups through the third postoperative day. The opioid consumption was significantly lower in the self-coiling catheter group on the day of surgery and on the second and third postoperative days (p = 0.04, p = 0.03 and p = 0.04, respectively).ConclusionThe self-coiling catheter offers a better postoperative pain control and a lower dislocation rate within the tissue when blocking the popliteal sciatic nerve compared to a conventional catheter. Further trials in large patient cohorts are warranted to investigate the potential beneficial effects of self-coiling catheters for other localisations and other application techniques.Trial registrationThe trial was registered at German Clinical Trials Register (DRKS) on 08/04/2020 (DRKS00020938, retrospectively registered).

Estimation of the minimum effective volume of 0.5% bupivacaine for ultrasound-guided popliteal sciatic nerve block in diabetic patients with neuropathy.

Background and Aims:The safety of conventional regional nerve block techniques in patients with established neuropathies, such as diabetic peripheral neuropathy (DPN), is still unclear. We designed this prospective dose finding study to identify the minimum effective local anaesthetic volume of 0.5% bupivacaine for ultrasound-guided subparaneural popliteal sciatic nerve block in 90% of DPN patients undergoing below-knee surgery (MELAV90).Methods:Fifty-three patients with diabetic peripheral neuropathy and scheduled for below knee surgical procedure received popliteal sciatic nerve block under ultrasound guidance. The initial local anaesthetic volume used was 10 ml of 0.5% bupivacaine. The subsequent local anaesthetic volume allocation was based on biased-coin-design. Accordingly, the local anaesthetic volume given to each subject was based on the block outcome of the previous patient. The study included patients prospectively until 45 successful blocks were obtained. The primary measurement was the minimum effective local anaesthetic volume resulting in a successful subparaneural popliteal sciatic nerve block in 90% of DPN patients. The MELAV90 was calculated using isotonic regression and a 95% confidence interval bootstrapping method.Results:The study included 53 patients to obtain 45 successful blocks. The MELAV90 of 0.5% bupivacaine was obtained at 5.85 ml (95% confidence interval, 5.72 to 6.22 ml). Eight patients needed supplemental anaesthesia to complete the surgery. No other complications were noted.Conclusion:For patients with diabetic peripheral neuropathy undergoing below-knee surgery, the MELAV90 of 0.5% bupivacaine for subparaneural popliteal sciatic nerve to achieve surgical anaesthesia was 5.85 ml.

Does ultrasound-guided popliteal-sciatic nerve block have superior pain control in pediatric foot and ankle surgery? A randomized control trial

BackgroundTendon surgery in the pediatric foot and ankle could cause severe postoperative pain, which may lead to psychologic distress and chronic pain. This study was aimed to compare the efficacy of a peripheral nerve block (PNB) and local surgical site infiltration (LSI) in pediatric foot and ankle tendon surgery. MethodsForty pediatric patients, who underwent foot and ankle tendon surgery were enrolled. Patients age 1–6 years old were allocated to group 1 and 7–15 years old were group 2. The popliteal-sciatic nerve block with 0.5% Bupivacaine (0.25 ml/kg) for group 1A and 2A. Group 1B and 2B received 0.5% Bupivacaine (0.25 ml/kg) local injection before wound closure. Pain score was recorded using CHEOPS in 1–6 years (Group1A, 1B), NRS in age 7–15 years (Group 2A, 2B). The post-operative morphine consumption and complications were recorded. ResultsFor 7–15 years, pain score in group 2B was more than group 2A at postoperative 2 and 6 h [Mean difference (95% CI); -3.4 (-6.4 to -0.3), and -2 (-4.4 to 0.5), respectively], and reached MCID of 2. The number of morphine consumption was significantly higher in group 2 B at 0–6 and 6–12 h post-operatively [Mean difference (95% CI); -0.8 (-1.4 to -0.2), and -0.6 (-1.1 to -0.1), respectively, with p-value < 0.05]. For 1–6 years, there was no significant difference in pain score and number of postoperative morphine consumption. ConclusionsPNB and LSI provided effective pain management in patients aged 1–6 years old with no statistically significant difference. PNB showed significant superior pain control in patients aged 7–15 years old.

Effect of intravenous dexamethasone on the duration of postoperative analgesia for popliteal sciatic nerve block: a randomized, double-blind, placebo-controlled study.

BackgroundIntravenous (IV) dexamethasone prolongs the duration of a peripheral nerve block; however, there is little available information about its optimal effective dose. This study aimed to evaluate the effects of three different doses of IV dexamethasone on the duration of postoperative analgesia to determine the optimal effective dose for a sciatic nerve block.MethodsPatients scheduled for foot and ankle surgery were randomly assigned to receive normal saline or IV dexamethasone (2.5 mg, 5 mg, or 10 mg). An ultrasound-guided popliteal sciatic nerve block was performed using 0.75% ropivacaine (20 ml) before general anesthesia. The duration of postoperative analgesia was the primary outcome, and pain scores, use of rescue analgesia, onset time, adverse effects, and patient satisfaction were assessed as secondary outcomes.ResultsCompared with the control group, the postoperative analgesic duration of the sciatic nerve block was prolonged in groups receiving IV dexamethasone 10 mg (P < 0.001), but not in the groups receiving IV dexamethasone 2.5 mg or 5 mg. The use of rescue analgesics was significantly different among the four groups 24 h postoperatively (P = 0.001) and similar thereafter. However, pain scores were not significantly different among the four groups 24 h postoperatively. There were no statistically significant differences in the other secondary outcomes among the four groups.ConclusionsThis study demonstrated that compared to the controls, only IV dexamethasone 10 mg increased the duration of postoperative analgesia following a sciatic nerve block for foot and ankle surgery without the occurrence of adverse events.

Factors Associated With Minimum Effective Volume of Lidocaine 1.5% for Sciatic Nerve Blocks.

The objectives of this study were to investigate the correlations between the minimum effective volume (MEV) of lidocaine 1.5% for an ultrasound-guided popliteal sciatic nerve block and individual factors including the cross-sectional nerve area, sex, age, body mass index, and the depth of the sciatic nerve and to evaluate the safety of combined femoral and sciatic nerve blocks by monitoring the plasma concentration of local anesthetics. Forty patients received combined single-shot femoral and continuous sciatic nerve blocks. The femoral nerve block was performed with an in-plane technique and 15 mL of lidocaine 1.5%. A continuous peripheral nerve block annular tube was positioned between the tibial and peroneal nerves inside the paraneural sheath. Thirty minutes after the femoral nerve block, a loading dose of 5 mL of lidocaine 1.5% was given to block the sciatic nerve after obtaining the maximum compound muscle action potential (CMAP) amplitude using nerve conduction studies. Additional lidocaine 1.5% was pumped at a rate of 30 mL/h through the indwelling annular tube if, after 8 minutes, the CMAP amplitude was still present. The CMAP amplitude monitored by the nerve conduction studies and pinprick tests were recorded every 2 minutes after the administration of lidocaine 1.5%. When the CMAP amplitude decreased to nearly 0 mV, this MEV was recorded. The influences of the cross-sectional area of the sciatic nerve, sex, age, body mass index, and the depth of the sciatic nerve on the MEV were analyzed using stepwise multiple linear regression. Blood samples were collected from 10 patients to evaluate the safety of combined femoral and sciatic nerve blocks by ultra-performance liquid chromatography-tandem mass spectrometry. Blood was drawn at 0 minutes before femoral nerve injection; 0 minutes before sciatic nerve injection; 8 minutes after sciatic nerve injection; and 0, 10, 20, 30, 45, 60, 75, 90, and 120 minutes after the pumping of lidocaine 1.5% stopped. A significant correlation was found between the MEV of lidocaine 1.5% and the cross-sectional area of the sciatic nerve (r=0.459), with a regression equation of the MEV (mL)=5.969+0.095×(the cross-sectional area of the sciatic nerve). The coefficient of determination was 0.211 (P<0.05). The MEV of lidocaine 1.5% for complete sciatic nerve blocks ranged from 7 to 15 mL. The maximum concentrations of lidocaine, monoethylglycinexylidide, and glycinexylidide were 1672.9 (227.6), 265.7 (32.7), and 42.2 (22.4) ng/mL, respectively. There is a positive correlation between the cross-sectional area of the sciatic nerve and the MEV. The regression equation can help to predict the MEV of lidocaine 1.5% for popliteal sciatic nerve blocks. The maximum concentrations of lidocaine and its metabolites did not approach toxic threshold limits in this study.

Clinical application of ultrasound-guided femoral nerve and popliteal sciatic nerve block in patients undergoing foot and ankle surgery

Objective To observe the application of ultrasound-guided femoral nerve block(FNB) and popliteal sciatic nerve block(PSNB) in patients undergoing foot and ankle surgery. Methods From August 2015 to August 2017, 60 patients scheduled for foot and ankle surgery undergoing laryngeal mask airway (LMA) general anesthesia in the People′s Hospital of Langfang were randomly divided into 3 groups by the random number table, with 20 cases in each group.Before transfer patients from bed to operating table, A group received dezocine 5 mg iv, B group received FNB combined with PSNB(distal to the sciatic nerve bifurcation), C group received FNB combined with PSNB(proximal to the sciatic nerve bifurcation). A total of 40 mL of 0.375% ropivacaine were injected guided by ultrasound in B group and C group.The time of sufficient sensory block and awake, the dosage of remifentanil and propofol were recorded.Pain was assessed using visual analogue scale (VAS) pre- and post block.The incidence of sleepiness, postoperative nausea and vomiting (PONV), agitation, pain and adverse reaction were also recorded. Results The time of sufficient sensory block and awake, the dosage of remifentanil and propofol in A, B and C group: A group(not measured), (21.6±1.6)min, (1183±17)μg, (665.0±6.7)mg; B group (25.5±2.5)min, (15.3±1.4)min, (635±16)μg, (455.0±6.5)mg; C group (19.6±2.3)min, (14.9±1.5)min, (598±14)μg, (438.0±9.9)mg.The time of awake, the dosage of remifentanil and propofol in B group and C group were significantly lower than those in A group (F=44.07, 52.41, 62.45, all P<0.05). The time of sufficient sensory block in C group was lower than that in B group(t=15.69, P<0.05). The VAS scores at T2, T3 and T4 in A, B and C group: A group (4.5±0.6)point, (8.4±0.5)point, (6.1±0.9)point; B group (2.6±0.5)point, (3.9±0.3)point, (2.4±0.6)point; C group (2.5±0.4)point, (2.3±0.5)point, (1.1±0.5)point.The VAS scores in B group or C group were significantly lower than those in A group (F=52.36, 72.82, 75.41, all P<0.05). The VAS scores at T3 and T4 in C group were significantly lower than those in B group (t=18.42, q=14.55, all P<0.05). The incidence rates of sleepiness, PONV, agitation and incision pain in A, B and C group: A group (25%, 25%, 15%, 15%, 50%); B group(0%, 5%, 0%, 0%, 10%); C group(0%, 5%, 0%, 0%, 0%). The number of patients who had adverse reactions in B or C group were significantly lower than those in A group (χ2=8.51, 8.73, 10.11, 10.11, 9.69, all P<0.05). The incidence rate of incision pain at sober in C group was lower than that in B group(χ2=10.89, P<0.05). Conclusion The ultrasound-guided FNB and PSNB(proximal to the sciatic nerve bifurcation) can obviously shorten the onset time, reduce the dosage of general anaesthetic.It has effective analgesia during transfer of patients from bed to operating table and sober. Key words: Ultrasound; Femoral nerve block(FNB); Popliteal sciatic nerve block(PSNB); Foot and ankle surgery; Laryngeal mask airway(LMA); Distal popliteal sciatic nerve block; Proximal popliteal sciatic nerve block; Ropivacaine

Ultrasound-guided popliteal sciatic nerve block: an effective alternative technique to control ischaemic severe rest pain during endovascular treatment of critical limb ischaemia.

PurposeThere are challenges with pain management related to a severely ischaemic limb. Although opioid-based treatment has been the cornerstone of pain relief, the use of these drugs should be limited because of their side effects in such vulnerable patients. We evaluated the utility and efficiency of sciatic nerve block as an alternative method to relieve severe rest pain during endovascular treatment of critical limb ischaemia.Material and methodsWe retrospectively investigated 10 patients who received ultrasound-guided popliteal sciatic nerve block for the relief of severe rest pain during endovascular treatment of critical limb ischaemia. The degree of pain relief was evaluated by using subjective criteria, from no relief of pain (= 1) to complete relief of pain (= 4). Details of endovascular treatment, time to perform the block, amount of local anaesthetics, duration of the block, need for supplemental analgesia, patient and operator satisfaction, and complications were recorded.ResultsAll blocks were technically successful, and all of the patients had complete resolution of the pain within five minutes. The degree of pain relief was 3 in two patients and 4 in eight patients. All patients were satisfied with the block anaesthesia, and no patient required additional analgesia during this period. Operator satisfaction was very good in all cases. Complications secondary to block did not occur in any patient.ConclusionsUltrasound-guided popliteal sciatic nerve block provides effective pain control, which results in excellent patient and operator satisfaction during endovascular treatment of critical limb ischaemia with severe rest pain.

Effects of dexmedetomidine on responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block

Objective To evaluate the effects of dexmedetomidine on responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block. Methods Eighty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 22-63 yr, weighing 47-81 kg, scheduled for elective foot surgery under ultrasound-guided popliteal sciatic nerve block combined with saphenous nerve block, were divided into 2 groups (n=40 each) using a random number table method: control group (group C) and dexmedetomidine group (group D). Dexmedetomidine was intravenously infused for 10 min in a dose of 1 μg/kg in group D, and the equal volume of normal saline was given instead in group C. Blood samples were taken from the internal jugular vein before using the tourniquet (T0) and at 30 and 60 min after releasing the tourniquet (T1-2) for determination of the levels of c-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), methane dicarboxylic aldehyde (MDA) and superoxide dismutase (SOD) in plasma.The time to responses to tourniquet, tourniquet tolerance time and tourniquet tolerance period were recorded.The occurrence of hypotension, bradycardia and nausea and vomiting was also recorded. Results Compared with the baseline at T0, the concentrations of plasma CRP, TNF-α and MDA were significantly increased and the activity of plasma SOD was decreased at T1, 2 in the two groups (P<0.05). Compared with group C, the concentrations of plasma CRP, TNF-α and MDA were significantly decreased and the activity of plasma SOD was increased at T1, 2, the time to responses to tourniquet, tourniquet tolerance time and tourniquet tolerance period were prolonged, and the incidence of bradycardia was increased in group D (P<0.05). Conclusion Dexmedetomidine can reduce responses to tourniquet in patients undergoing lower extremity surgery with peripheral nerve block. Key words: Dexmedetomidine; Nerve block; Tourniquets; Lower extremity

Comparison of peripheral nerve blockade characteristics between non-diabetic patients and patients suffering from diabetic neuropathy: a prospective cohort study.

Animal data have demonstrated increased block duration after local anaesthetic injections in diabetic rat models. Whether the same is true in humans is currently undefined. We, therefore, undertook this prospective cohort study to test the hypothesis that type-2 diabetic patients suffering from diabetic peripheral neuropathy would have increased block duration after ultrasound-guided popliteal sciatic nerve block when compared with patients without neuropathy. Thirty-three type-2 diabetic patients with neuropathy and 23 non-diabetic control patients, scheduled for fore-foot surgery, were included prospectively. All patients received an ultrasound-guided popliteal sciatic nerve block with a 30 ml 1:1 mixture of lidocaine 1% and bupivacaine 0.5%. The primary outcome was time to first opioid request after block procedure. Secondary outcomes included the time to onset of sensory blockade, and pain score at rest on postoperative day 1 (numeric rating scale 0-10). These outcomes were analysed using an accelerated failure time regression model. Patients in the diabetic peripheral neuropathy group had significantly prolonged median (IQR [range]) time to first opioid request (diabetic peripheral neuropathy group 1440 (IQR 1140-1440 [180-1440]) min vs. control group 710 (IQR 420-1200 [150-1440] min, p = 0.0004). Diabetic peripheral neuropathy patients had a time ratio of 1.57 (95%CI 1.10-2.23, p < 0.01), experienced a 59% shorter time to onset of sensory blockade (median time ratio 0.41 (95%CI 0.28-0.59), p < 0.0001) and had lower median (IQR [range]) pain scores at rest on postoperative day 1 (diabetic peripheral neuropathy group 0 (IQR 0-1 [0-5]) vs. control group 3 (IQR 0-5 [0-9]), p = 0.001). In conclusion, after an ultrasound-guided popliteal sciatic nerve block, patients with diabetic peripheral neuropathy demonstrated reduced time to onset of sensory blockade, with increased time to first opioid request when compared with patients without neuropathy.

Ultrasound-Guided Popliteal Sciatic Nerve Block for an Ankle Laceration in a Pediatric Emergency Department

Although ultrasound-guided peripheral nerve block has recently been introduced into pediatric emergency departments, knowledge of its use is limited. We present here a case demonstrating the safety and effectiveness of ultrasound-guided popliteal sciatic nerve block for a pediatric spoke injury in a pediatric emergency department setting.

Ultrasound-Guided Popliteal Sciatic Block Provides Adequate Analgesia During Urgent Endovascular Treatment of Critical Limb Ischemia with Resting Pain.

To demonstrate feasibility and safety of ultrasound-guided popliteal sciatic nerve block for providing analgesia during urgent endovascular treatment of critical limb ischemia with resting pain. Ultrasound-guided popliteal sciatic blocks were performed by an interventional radiologist in angiography suite immediately prior to commencement of urgent endovascular treatment of 30 critical limb ischemia patients. Subjective pain levels prior to and following sciatic block were assessed using the visual analog scale (VAS). Need for any supplemental anxiolytics or analgesics during treatment was recorded. Post-procedural evaluation of patient and operator satisfaction levels regarding the intervention was also documented. Ultrasound-guided sciatic block provided adequate analgesia in all patients; VAS scores were 0 (no pain) in 87% and 1-3 (mild to annoying pain) in 13%. Two patients required anxiolytic premedication. Additional analgesia was not required during course of endovascular treatment of any patients. Time necessary to perform sciatic block ranged 3-9 (mean 5.9±1.3) min. Median number of needle attempts was 1 (range 1-3). Onset of satisfactory block ranged from 5 to 20min (mean 9.4±2.6min). Mean treatment time was 102.2±36.7min, and balloon time was 22.4±6.1min. Patient and operator satisfaction with pain control were very good in all cases. There were no procedure-related complications. Ultrasound-guided popliteal sciatic block is a feasible and safe alternative for providing adequate analgesia during urgent endovascular treatment of critical limb ischemia with resting pain. Level 4, case series.

Diabetic neuropathy increases stimulation threshold during popliteal sciatic nerve block

BackgroundPeripheral nerve stimulation is commonly used for nerve localization in regional anaesthesia, but recommended stimulation currents of 0.3–0.5 mA do not reliably produce motor activity in the absence of intraneural needle placement. As this may be particularly true in patients with diabetic neuropathy, we examined the stimulation threshold in patients with and without diabetes. MethodsPreoperative evaluation included a neurological exam and electroneurography. During ultrasound-guided popliteal sciatic nerve block, we measured the current required to produce motor activity for the tibial and common peroneal nerve in diabetic and non-diabetic patients. Proximity to the nerve was evaluated post-hoc using ultrasound imaging. ResultsAverage stimulation currents did not differ between diabetic (n+55) and non-diabetic patients (n+52). Although the planned number of patients was not reached, the power goal for the mean stimulation current was met. Subjects with diminished pressure perception showed increased thresholds for the common peroneal nerve (median 1.30 vs. 0.57 mA in subjects with normal perception, P+0.042), as did subjects with decreased pain sensation (1.60 vs. 0.50 mA in subjects with normal sensation, P+0.038). Slowed ulnar nerve conduction velocity predicted elevated mean stimulation current (r+−0.35, P+0.002). Finally, 15 diabetic patients required more than 0.5 mA to evoke a motor response, despite intraneural needle placement (n+4), or required currents ≥2 mA despite needle-nerve contact, vs three such patients (1 intraneural, 2 with ≥2 mA) among non-diabetic patients (P+0.003). ConclusionsThese findings suggest that stimulation thresholds of 0.3–0.5 mA may not reliably determine close needle-nerve contact during popliteal sciatic nerve block, particularly in patients with diabetic neuropathy. Clinical trial registrationNCT01488474

Minimum effective anaesthetic volume of 0.5% ropivacaine for ultrasound-guided popliteal sciatic nerve block in patients undergoing foot and ankle surgery: determination of ED50 and ED95.

Compared to nerve stimulation or classic paraesthesia techniques, ultrasound (US)-guided popliteal sciatic nerve block requires a smaller volume of local anaesthetic. The up-and-down method was used to determine the minimum effective anaesthetic volume of 0.5% ropivacaine necessary for US-guided popliteal sciatic nerve block to achieve successful surgical anaesthesia for foot and ankle surgery. The study included 32 patients receiving an US-guided popliteal sciatic nerve bock. The starting dose of 0.5% ropivacaine was set at 30 ml, which was decreased by 3 ml if the block succeeded and increased by 3 ml if the block failed. After the injection of local anaesthetic, the degree of sensory and motor blockade of the tibial and common peroneal nerves was assessed every 5 minutes for 30 minutes. The ED50 and ED95 volumes of local anaesthetic were 6 ml and 16 ml, respectively. The success rates of sensory blockade of the tibial nerve and common peroneal nerve were 69% and 88%, respectively. The success rates of motor blockade of these nerves were 75% and 90%, respectively. The ED50 and ED95 of 0.5% ropivacaine for US-guided popliteal sciatic nerve block were 6 ml and 16 ml, respectively.

P850: Electrophysiological pattern in GLUT1 deficiency syndrome (A275T mutation)

s of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339 S269 Figure 2. The relationship between muscle strength and transcranial stimulation motor evoked potential. Conclusions: There is the positive relation between the MEP amplitude and the muscle strength. So, the fixed quantity evaluation method using the statistical technique makes TCS-MEP reliable. And TCS-MEP may enhance us to remove tumors in central nervous system and at the same time preserve motor functions. Moreover this relation between MEP and muscle strength is useful for understanding the motor control system. P850 Electrophysiological pattern in GLUT1 deficiency syndrome (A275T mutation) C. Giliberto1, V. Sofia1, R. Barone2, R. Guerrini3, M. Zappia1 1University of Catania, Department G.F. Ingrassia, Section of Neurosciences, Catania, Italy; 2University of Catania, Pediatric Neurology, Department of Pediatrics, Catania, Italy; 3University of Florence, Pediatric Neurology, Unit and Laboratories, Children’s Hospital A. Meyer, Florence, Italy Question: Glucose transporter type 1 deficiency syndrome (GLUT1DS) is characterized by impaired glucose transport across the blood-brain barrier due to SLC2A1-gene mutation. GLUT1DS infancy onset shows epileptic encephalopathy, ataxia and microcephaly although paroxysmal exerciseinduced dyskinesia and epilepsy may also be observed. Exercise and recovery-induced modifications of GLUT4 and GLUT1 expression in human muscle have been reported.We describe clinical and electromyographyc correlates of a GLUT1DS patient with adult-onset of exercise-induced dystonia. Patients and methods: A 19 year old male with mild mental retardation presented with a two-year history of episodic stiffness in his calves and feet and painless flexion of the toes followed by leg weakness triggered by exertion and starvation and alleviated by rest and eating. His father had experienced exercise-induced leg dystonia at younger age. A heterozygous missense of mutation (c.823G>A; p.A275T) of SLC2A1 gene was found in the proband and his father.The proband underwent an electromyographyc study after voluntary contraction (5 minutes) to investigate muscle membrane excitability with the evaluation of compound muscle action potential (CMAP) amplitude. Results: The test disclosed significant decrement of CMAP amplitude up to −42% (n.v.≤−20%) after 40 minutes from exercise with respect to the pre-exercise CMAP amplitude (baseline). The same test repeated after carbohydrate-rich food intake showed a significant improvement of CMAP from baseline (−26%). Conclusions: The electrophysiological study after exercise showed a reduction of CMAP amplitude in this patient with GLUT1DS (A275T mutation). Our data suggest a possible involvement of muscle membrane excitability in GLUT1DS. P851 Tracking the spatiotemporal profile of cortical and peripheral motor axon hyperexcitability in amyotrophic lateral sclerosis E. Bakola1, P. Kokotis1, R. Carr2, M. Schmelz2, M. Rentzos1, T. Zambelis1, N. Karandreas1 1University of Athens, Medical School, Department of Neurology, Athens, Greece; 2University of Heidelberg, Mannheim Medical School, Department of Anesthesiology, Mannheim, Germany Question: Recent studies using magnetic and electrical excitability tracking tools have confirmed early hyperexcitability in ALS. This study sets out to use excitability testing to examine directly the spatiotemporal profile of cortical and peripheral hyperexcitability in ALS patients simultaneously, to associate these parameters to the clinical course of the disease and to compare them with healthy controls. Methods: Nineteen patients with first-diagnosed definite ALS (group A), four patients with advanced disease (group B) and ten control healthy volunteers (group C) were included in the study. Multiple axonal excitability properties (threshold electrotonus, strength-duration time constant, recovery cycle, current-threshold relationship) and TMS investigations including measurement of resting motor threshold (RMT) and motor evoked potential (MEP) were measured. Results: In group A there were greater changes in depolarizing threshold electrotonus (TD) compared with group B (t-test p<0.03). No differences in recovery cycle, strength-duration time constant, current-threshold relationship were noted between the three groups. Regarding the cortical excitability parameters, there was a significant decrease in the slope of MEP amplitude to TMS intensity in group B with the advanced disease in comparison to controls (Mann-Whitney U test p<0.05). ANCOVA showed strong correlation between TD and slope of cortical excitability (p<0.01) after correcting for the status of the disease (groups A,B,C). Conclusions: These are preliminary results of an ongoing study trying to understand the changes in axonal and cortical excitability in first-diagnosed and advanced disease in order to provide insight into the pathophysiological basis of the disease and furthermore provide useful information for the best treatment approach in the future.