|Year : 2020 | Volume
| Issue : 1 | Page : 1-7
Ultrasound-guided femoro–sciatic nerve block with and without using nerve locator for below-knee surgeries
Ibrahim A Ibrahim Walash, Ashraf M Mostafa, Ayman A Abdel-Maksoud Rayan, Wesam E Sultan
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||30-Dec-2018|
|Date of Acceptance||02-Apr-2019|
|Date of Web Publication||16-Apr-2020|
Ibrahim A Ibrahim Walash
Shibin El Kom, Menoufia Governorate
Source of Support: None, Conflict of Interest: None
Background Femoral and sciatic nerve blocks is a suitable technique for below-knee surgeries compared with neuroaxial and general anesthetic techniques.
Objectives To evaluate the efficacy of ultrasound-guided femoral and sciatic nerve blocks with and without using a nerve locator in below-knee surgeries.
Patients and methods Between May 2017 and May 2018, we conducted our randomized, observer-blinded prospective clinical study. Sixty patients underwent below-knee surgeries in Menoufia University Hospitals were involved and divided into two groups of 30 patients each. The groups were assigned into two: group A received ultrasound-guided femoral and sciatic nerve block and in group B, nerve block was done using combined ultrasound with a nerve locator.
Results The onset time of motor block was significantly shorter in the nerve locator group than in the ultrasound-only group (P<0.001). There was no significant statistical difference among the studied groups as regards the heart rate, blood pressure, and onset time of sensory block.
Conclusion Adding nerve locator to the ultrasound-guided nerve block technique has minimal impact on the efficacy of the technique.
Keywords: below-knee surgeries, femoro–sciatic nerve block, hemodynamic stability, nerve locator, ultrasound guided
|How to cite this article:|
Ibrahim Walash IA, Mostafa AM, Abdel-Maksoud Rayan AA, Sultan WE. Ultrasound-guided femoro–sciatic nerve block with and without using nerve locator for below-knee surgeries. Res Opin Anesth Intensive Care 2020;7:1-7
|How to cite this URL:|
Ibrahim Walash IA, Mostafa AM, Abdel-Maksoud Rayan AA, Sultan WE. Ultrasound-guided femoro–sciatic nerve block with and without using nerve locator for below-knee surgeries. Res Opin Anesth Intensive Care [serial online] 2020 [cited 2020 May 31];7:1-7. Available from: http://www.roaic.eg.net/text.asp?2020/7/1/1/282586
| Introduction|| |
The use of ultrasound-guided peripheral nerve blocks (PNBs) have been extensive in patients undergoing below-knee lower limb surgeries especially in those with critical comorbidities who cannot tolerate alteration of the hemodynamic status. Moreover, using ultrasound-guided block makes localization of the nerves more accurate ,.
Electrical stimulation of a peripheral nerve usually results in muscular twitching, paresthesia, or a combination of both depending on the nerve morphology. An electrical nerve locator will stimulate muscular twitching at a distance close to the nerve without actually touching it, hence, providing greater accuracy for local anesthetic (LA) deposition.
Recently, several developments have led to an increased interest in lower extremity PNBs, including recognition of transient neurological symptoms associated with spinal anesthesia and evidence of improved rehabilitation outcome with lower limb PNBs. It is desirable to provide effective anesthesia, rapid and an uneventful recovery, persistent postoperative analgesia, and early ambulation to patients .
PNBs are ideally suited for lower limb surgeries because of the peripheral location of the surgical site and the potential to block pain pathways at multiple levels. In contrast to other anesthetic techniques such as general or spinal anesthesia, properly conducted PNBs avoid hemodynamic instability, facilitate postoperative pain management, and assure a timely discharge of the patient. When long-acting LA are used, PNBs can be used to provide excellent anesthesia and postoperative analgesia in patients undergoing a wide variety of surgical procedures ,,,.
The aim of this study was to compare the effectiveness of using ultrasound only and ultrasound with nerve locator in nerve blocks.
| Patients and method|| |
An ethical clearance was taken for the study beforehand and an anesthetist was put on standby. Written and verbal consent was taken from patients. This randomized, observer-blinded prospective clinical study involved 60 patients divided into two groups, each of 30 patients, of both sexes, in the age group of 18–70 years, American Society of Anesthesiologists (ASA) classification I–III, scheduled to undergo elective and emergency below-knee surgeries. The exclusion criteria included allergy to the LA used, bleeding disorders, and localized infection at the site of injection, neurological disorders, psychological disorders, and morbid obesity.
After history taking, clinical examination of routine laboratory investigations, peripheral venous cannulation, a preload of 6 ml/kg of lactated Ringer’s solution with 2 mg midazolam was given to sedate the patients. Following this, the patients are either divided into:
- Group A: femoral and sciatic nerve block using ultrasound only.
- Group B: femoral and sciatic nerve block using ultrasound combined with a nerve locator.
Group A (femoral and sciatic nerve block using ultrasound only): 30 patients
Femoral nerve block
The femoral area was sterilized using povidone-iodine and alcohol and then drapes were put on the patient’s thigh, then with the operator on the right-hand side for blocks on both sides and vice versa for a left-handed operator. The ultrasound machine ‘SonoSite M-Turbo’ was placed on the opposite side so that the operator’s line of sight, needle, and the screen is in a straight line.
The femoral area was scanned behind the midpoint of the inguinal ligament and the depth of image was set at 3–5 cm and a linear high frequency 8–12 MHz) probe was placed perpendicular to the course of the femoral nerve., medial to the lateral sliding movements of the transducer-aided visualization of the pulsatile femoral artery. Structures that were visualized: fascia iliaca, femoral artery, immediately below and lateral was the femoral nerve in a wedge-shaped space. The femoral nerve was typically hyperechoic and lied in a sulcus in iliopsoas inferiorly. In-line insertion of the needle to reach below fascia iliaca and then a volume of 15 ml of LA (7.5 ml bupivacaine 0.5%+7.5 ml lidocaine 2%) was injected to perform the block.
Sciatic nerve block
By using the Labat approach, the patient was positioned with the side for the block uppermost, flexed partially at the hip and knee joints.
The iliac area was sterilized using povidone-iodine and alcohol, and then drapes were put on the patient’s thigh, then with the operator on the right-hand side for blocks on both sides and vice versa for a left-handed operator. The ultrasound machine ‘Sonosite M-turbo’ was placed on the opposite side so that the operator’s line of sight, needle, and the screen is in a straight line.
A curvilinear low-frequency (3–9 MHz) probe was used to do a scan of the subgluteal region below a line from ischial tuberosity and greater trochanter which are seen as two hyperechoic bony prominence; the gluteus maximus muscle was seen as the most superficial muscular layer bridging the two osseous structures; sciatic nerve was seen deep into the gluteus maximus muscle and superficial to the quadratus femoris muscle as an oval or roughly triangular hyperechoic structure. A volume of 25 ml of LA (12.5 ml bupivacaine 0.5%+12.5 ml lidocaine 2%) was injected to perform the block.
Group B (femoral and sciatic nerve block using ultrasound combined with a nerve locator): 30 patients
Femoral nerve block
After scanning the inguinal area using a linear probe, the needle insertion site was immediately lateral to the femoral artery, the needle was introduced into the sagittal, slightly cephalad plane. Using a nerve stimulator, stimulation of the femoral nerve was indicated by patellar movement as the quadriceps muscle contracts. The anterior division of the femoral nerve (which innervates the sartorius muscle) was identified first. Stimulation of this branch led to contraction of the sartorius muscle on the medial aspect of the thigh and should not be accepted, as the articular and muscular branches arise from the posterior division of the femoral nerve. When the sartorius muscle twitch occurred, the needle was simply redirected laterally (without withdrawal) and advanced several millimeters deeper until twitches of the patella were seen, then a volume of 15 ml LA (7.5 ml bupivacaine 0.5%+7.5 ml lidocaine 2%) was injected.
Sciatic nerve block
After scanning the subgluteal region and identifying the sciatic nerve, a nerve stimulator needle was advanced to it. The nerve stimulator was initially set to deliver a 1.5 mA current to allow detection of the twitches of the gluteal muscles and stimulation of the sciatic nerve. As the needle was advanced, twitches of the gluteal muscles were usually observed first indicating the shallow position of the stimulating needle. As the needle was advanced, the gluteal twitches disappear, and brisk response of the sciatic nerve was observed (hamstring, calf, foot, or toe twitches). The stimulating current was gradually reduced until twitches were still seen or felt at 0.2–0.5 mA, typically at a depth of 5–8 cm. At this level, twitches of the hamstring were acceptable because the separation of the neuronal branches to the hamstring muscle occurs below this level. Then a volume of 20–25 ml of LA was injected.
The results were collected, tabulated, and statistically analyzed by an IBM compatible personal computer with the Statistical Package for the Social Sciences, version 20 (SPSS Inc. released 2011, IBM SPSS statistics for Windows, version 20.0; IBM Corp., Armonk, New York, USA). Two types of statistical analysis were done: (a) descriptive statistics, for example, was expressed in: mean and SD and (b) analytic statistics, for example, Student’s t test is a test of significance used for comparison of quantitative variables between two groups of normally distributed data. While Mann–Whitney’s test was used for comparison of quantitative variables between two groups of not normally distributed data. A P value of less than 0.05 was considered statistically significant.
ECG and Heart rate and oxygen saturation were monitored continuously, and arterial pressure was measured every 5 min during the surgery. Onset and duration of sensory block was analyzed according to loss of pinprick sensation. Onset and duration of motor block and the degree of motor block were assessed by the modified Bromage score.
| Results|| |
Patients’ demographic data (age, sex, and ASA classification) were not comparable between the two groups ([Table 1]). As regards the onset time of motor block there was significant statistical difference among the studied groups as the patients receiving the nerve block using the combined ultrasound with a nerve locator (group B) showed a significant onset time of 24.8±2.8 min over ultrasound only (group A) 27.6±9.9 min ([Table 2]). As regards the onset time of sensory block, duration of sensory block, and duration of motor block there was no significant difference between both techniques ([Table 2]). As regards the degree of nerve block, there was significant difference between both groups with a success rate of 93.3% in group B over a success rate of 80% in group A ([Table 3]). As regards the mean arterial blood pressure, there was no significant difference between both techniques ([Table 4]).
|Table 1 Comparison between the studied groups as regards demographic data (N=60)|
Click here to view
|Table 2 Comparison between the studied groups as regards onset and duration of procedures (N=60)|
Click here to view
|Table 3 Comparison between studied groups as regards anatomical variation and degree of nerve block (N=60)|
Click here to view
|Table 4 Comparison between studied groups as regards mean arterial blood pressure (mmHg) in relation to time (N=60)|
Click here to view
| Discussion|| |
The present method of PNB is an extremely useful and effective alternative technique for lower limb operative procedures in which the whole of the lower limb can be anesthetized using the two-puncture technique. This can be applied to any patient undergoing extensive lower limb surgery irrespective of whether he is fit for spinal or general anesthesia.
The aim of this study is to compare the effectiveness of using ultrasound with a nerve locator versus using ultrasound-only guided combined femoral and sciatic nerve blocks for below-knee surgeries.
Femoral nerve block is a basic nerve block technique that carries a low risk of complications and has significant clinical applicability for surgical anesthesia Winnie described the femoral (3-in-1) block using a single injection of a LA solution which blocks the femoral, lateral cutaneous, and obturator nerves . When combined with the sciatic nerve block, anesthesia of almost the entire lower extremity from the mid-thigh level can be achieved.
Patients in our study has performed a variety of operations, for example, below-knee amputation, diabetic foot debridement, fracture metatarsal bone fixation with k-wire, tibial plate removal, Nancy nail removal, and other surgical procedures.
Davies and Mcglade  have shown that without a nerve stimulator, sciatic nerve blocks are frequently unsuccessful. Therefore, a vast majority of sciatic nerve blocks are performed using insulated needles and nerve stimulators. In our study, the block was achieved with the use of a nerve stimulator in group B with a success rate of 93.3%; group A in which we used the ultrasound the success rate was only 80%.
In 1930, Labat  first proposed a posterior approach to the sciatic nerve block. In the present study of 60 cases, the classical posterior approach of Labat  was used in all patients because it is easy to apply, less painful, and more convenient to the patients.
In our study, we used a 15 ml mixture of 7.5 ml 2% lidocaine, 7.5 ml 0.5% bupivacaine for the femoral nerve block, and a 20–25 ml mixture containing 10 ml of 2% lidocaine, and 10 ml of 0.5% bupivacaine for the sciatic nerve block. Most of the patients in the study were from 18 to 70 years of age with a mean age of 48±14.4 years, because we wanted to assess the effectiveness of the PNB by avoiding the risk and disadvantages of general anesthesia/central nerve block in patients with cardiac, respiratory, and renal diseases.
Kumar and Singh  reported the use of combined sciatic and femoral 3-in-1 blocks in high-risk elderly patients for lower limb amputations (mean age, 70.71±8.73 years).
Among the selected patients, 40% of them had an ASA risk of grade II and 36.7% had an ASA risk of grade III.
Singh et al.  also concluded that combined sciatic and femoral (3-in-1) block can be given by choice in critically ill and hemodynamically unstable patients in the place of a central neuraxial block.
Gligorijevic  also concluded that in emergency and high-risk patients, a combined sciatic and femoral 3-in-1 block can be extremely useful and effective for any surgery on the lower limb.
The onset time for the sensory block was defined as the time from injection of the LA to point 1 scale of sensory block in any area supplied by femoral and sciatic nerves. In this study, it was found to be 19.2±7.6 min in group A, 15.6±2.3 min in group B which was comparable to the study done by Singh and colleagues who reported that the onset of time for sensory block was 12.56±5.36 min.
In other studies, Chakravarthy et al.  reported that the onset time for analgesia was 2.03±4.7 min but they used 50 ml of 1% lignocaine and Urbanek  reported a sensory onset time of 27 min in the bupivacaine group in his study of 3-in-1 block.
The onset time for motor block was defined as the time from injection of an LA to point 1 scale Bromage. In this study, it was 27.6±9.9 min in group A, 24.8±2.8 min in group B, while Singh and colleagues found that the onset time for the motor block was 21.3±9.94 min with 1% lignocaine and 0.25% bupivacaine in their study. The onset of sensory blockade was seen to precede onset of motor block. This is because of the fact that motor fibers are thick and located in the center of the nerve.
Another point checked was the duration of sensory block. Factors that influence the duration of sensory block are the LA drug, dose, and the concentration, which were kept constant in all patients in these study groups. It was defined as the time from the onset of sensory block to the first analgesic demand by the patient. In this study, it was 117±34.4 min in group A and 123.2±24.7 min in group B. Our study results are comparable with the studies by Chakravarthy et al.  who reported that the duration of sensory block was 203.1±29.8 min and Fournier et al.  who reported 4–6 h of sensory block after 3-in-1 block.
Duration of the motor blockade was 149.07±39.2 min in group A, 155.5±23.09 min in group B. Chakravarthy et al.  reported that motor block regression time was 180±22.5 min with 50 ml 1% lignocaine for the combined sciatic and femoral 3-in-1 block, whereas we used 10 ml 2% lidocaine and 10 ml 0.5% bupivacaine.
In our study, heart rate, systolic blood pressure, diastolic blood pressure, and mean blood pressure were recorded during the preoperative, intraoperative, and postoperative periods. All these parameters did not change significantly.
Our study results are comparable with the study by Kumar and Singh , Singh et al. , Chakravarthy et al. , Fowler and Sumons , Gligorijevic , Zaric and Boysen , Barton et al. , Casati and Cappelleri , Fanelli et al. , and Franqois and Singelyn .
Success of the PNB requires proper technique of nerve localization, needle placement, and LA injection. We performed this technique using ultrasound only and ultrasound combined with the nerve locator technique.
Out of the 60 patients, six patients of group A had an incomplete effect (success rate of 80%) in whom the surgery was proceeded by general anesthesia with endotracheal intubation and controlled ventilation and they were maintained with O+isoflurane+muscle relaxant while two patients of the 30 patients of group B had an incomplete effect (success rate of 93.3%).
Singh and colleagues also reported the high reliability and relatively low failure rate (4%) in their study. Kumar and Singh also reported a success rate of 99.44% in their study. Our study results are comparable with both of them.
The complications associated with this block are LA toxicity, neuraxial block due to proximal spread, and neurological complication which can be related to a PNB including needle trauma, intraneuronal injection, and neuronal ischemia. Infectious complications such as cellulitis, neuritis, and skin infection around the injection site are more associated with continuous nerve block techniques rather than a single injection technique.
In our study, none of the patients had any complications either intraoperative or postoperative. Our study results are comparable with the following studies: Zaric and Boysen reported that the incidence of side effects was very low (P<0.05) in the PNB group compared with the epidural group; Franqois and Singelyn observed that continuous 3-in-1 block induces nearly four times fewer side effects than epidural analgesia; Fowler and Sumons reported that PNB may provide effective unilateral analgesia with lower incidence of opioid-related and autonomic side effects and fewer serious neurological complications compared with epidural analgesia; Kumar and Singh also found no complication intraoperatively or postoperatively.Several systematic reviews compared the different effects of ultrasound alone with a nerve locator such as one Cochrane review. It indicated that ultrasound had success rates similar to a nerve locator, but may reduce complication rates such as vascular puncture or hematoma formation . One systematic review  including 11 studies also addressed that no study was powered to detect a difference of surgical block success rate between the ultrasound and the nerve locator group. The reason as to why there is not any systematic review on comparison of ultrasound-guided nerve block with a nerve locator and ultrasound without a nerve locator may partially be due to the significant inconsistency in defining the block success rate. As for the low incidence of complications, two large observational studies may be powered to illustrate this issue. One study  observed 3290 cases guided by a landmark nerve locator and 2146 cases by ultrasound guidance, five seizures, and three nerve injuries occurred in the nerve locator technique. The author concluded that ultrasound can decrease the incidence of LA systemic toxicity .
The use of ultrasound with a nerve locator can lengthen the procedure time than ultrasound alone. However, whether the use of ultrasound with a nerve locator can increase the block success rate than ultrasound alone is controversial. It was indicated that ultrasound with a nerve locator was not superior to ultrasound in decreasing tourniquet pain, opioid consumption, and neurological parathesia. Whether ultrasound with a nerve locator has a faster block onset time and lower arterial puncture than ultrasound alone remains unclear. The use of ultrasound with a nerve locator has higher sensory block success rate, faster block onset time, and less consumption of LA use than the nerve locator alone. For patients receiving lower limb nerve block, the use of ultrasound with a nerve locator lowered the risk of additional analgesia use, but this difference was not observed in patients receiving upper limb nerve block. The block procedure time between ultrasound with a nerve locator and ultrasound alone remains unclear due to the controversial results from included studies. The difference in arterial puncture between the ultrasound with the nerve locator group and the ultrasound group remains unclear.
| Conclusion|| |
Results of our study showed that:
- For adequately imaged ultrasound-guided femoral and sciatic nerve blocks, a positive motor response to nerve location does not increase the success rate of the block.
- Nerve location as an adjunct to ultrasound guidance may have a limited role.
- Nerve block anesthesia can be used as a good alternative of anesthesia in below-knee surgeries with less complications.
- These nerve blocks can be a suitable alternative in view of patient interest, especially when systemic illness or local conditions preclude the use of central neuraxial blocks.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Chung F, Mezei G. What are the factors causing prolonged stay after ambulatory anesthesia? Anesthesiology 1998; 89:A3.
Barton AC, Gleason D, D’Ercole FS, Klein SM, Greengrass RA, Steel SM. Haemodynamic effects of periphera nerve Blocks for amputation of the lower limb. Reg Anesth Pain Med 1999; 24:50.
Gligorijevic S. Combined block of the lower extremity. Curr OpinAnesthesiol 1997; 10:356–360.
Fowler SJ, Sumons J. Epidural analgesia compared with peripheral nerve blockade after major knee surgery: A systemic review and metaanalysis of randomized trials. Br J Anaesth 2008; 100:154–164.
Zaric D, Boysen K. A comparison of epidural analgesia with combined continuous femoral-sciatic nerve blocks after total knee replacement. Anesth Analg 2006; 102:1240–1246.
Casati A, Cappelleri G. General anesthesia, spinal block, or combined sciatic-femoral block for outpatient knee arthroscopy: acostanalysis. Anesthesiology 2001; 95:A16.
Fanelli G, Casati A, Aldegheri G, Beccaria P, Berti M, Leoni A et al.
Cardiovascular effects of two different regional anesthetic techniques for unilateral leg surgery. Acta Anesthesiol Scand 1998; 41:80–84.
Winnie AP, Ramamurthy S, Durrani Z. The inguinal paravascular technic of lumbar plexus anesthesia: the ‘3-in-1 block’. Anesth Analg 1973; 52:989–996.
Davies MJ, McGlade DP. One hundred sciatic nerve block: a comparison of localization techniques. Anesth Intensive Care 1993;76–78
Labat G. Regional anesthesia: its technic and clinical application. Philedelphia, PA: Saundrs; 1922.
Kumar R, Singh A. Amputation of lower extremity in diabetic and high resk patients under peripheral nerve blocks (combined sciatic and 3-in-1 femoral block). Kuwait Med J 2001; 33:310–316.
Singh A, Trivedi V, Kothari PU. Sciatic nerve block in combination with femoral nerve block for below knee surgery via the ‘classical‘ posterior approach. J Anesth Clin Pharmacol 2008; 24:444–446.
Chakravarthy V, Arya VK, Dhillon MS, Chari P. Compaiosn of regional nerve block to epidural anesthesia in day care arthroscopic surgery of the knee. Acta Orthop Belg 2004; 70:551–559.
Fournier R, Van-Genel E, Gaggero G, Boccovi S, Forster A, Gamulin Z. Postoperative analgesia with ‘3-in-1’ femoral nerve block after prothetic hip surgery. Can J Anaestha 1998; 45:34–38.
Franqois J, Singelyn MD. Effects of intravenous patient controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998; 87:88–92.
Walker KJ, McGrattan K, Aas-Eng K, Smith AF. Ultrasound guidance for peripheral nerve blockade. Cochrane Database Syst 2009; 4:CD006459.
Salinas FV. Ultrasound and review of evidence for lower extremity peripheral nerve blocks. Reg Anesth Pain Med 2010; 35:S16–S25.
Orebaugh SL, Williams BA, Vallejo M, Kentor ML. Adverse outcomes associated with stimulator-based peripheral nerve blocks with versus without ultrasound visualization. Reg Anesth Pain Med 2009; 34:251–255.
[Table 1], [Table 2], [Table 3], [Table 4]