Impact of ultrasound-guided popliteal sciatic nerve block on endovascular therapy for below-the-knee lesions in chronic limb-threatening ischemia.

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

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

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 versus traditional analgesia for early perioperative pain relief in severe chronic lower extremity arterial occlusive disease: A retrospective study.

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.

Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submissionBackground and AimsBackground...

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.

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.

Ultrasound-guided popliteal sciatic nerve block using a pocket-sized ultrasound machine: preliminary evidence

Because of its rapid onset time, recent years have seen an increase in the use of ultrasound (US)-guided popliteal sciatic nerve block (PSNB) via subparaneural injection for induction of surgical anesthesia. Moreover, in below-knee surgery, combined blocks, as opposed to sciatic nerve block alone, have become more common. These combined blocks often require a large volume of local anesthetic (LA), thus increasing the risk of local-anesthetic systemic toxicity (LAST). Thus, to decrease the risk of LAST, it is important to know the minimum effective volume (MEV) required for an adequate block. We, therefore, aimed to determine the MEV of ropivacaine 0.75% for induction of surgical anesthesia by the method of US-guided popliteal sciatic nerve block via subparaneural injection.Thirty patients underwent a US-guided PSNB with ropivacaine 0.75% at a 20-mL starting volume. Using a step-up/step-down method, we determined injection volumes for consecutive patients from the preceding patient's outcome. When an effective block was achieved within 40 minutes after injection, the next patient's volume was decreased by 2 mL. If the block failed, the next patient's volume was increased by 2 mL. The sensory and motor blockade was graded according to a 4-point scale. The block was considered a success if a combination of anesthesia and paresis (a score of 3 for both the sensory and motor nerves) was achieved within 40 minutes. The primary outcome measure was the MEV resulting in a successful subparaneural block of the sciatic nerve in 50% of patients (MEV50). Additionally, the data were processed with a probit regression analysis to determine the volume required to produce a complete sciatic nerve block in 90% of subjects (ED90).The MEV50 of 0.75% ropivacaine is 6.14 mL (95% confidence interval, 4.33–7.94 mL). The ED90 by probit analysis for a subparaneural injection was 8.9 mL (95% CI, 7.09–21.75 mL).The 6.14-mL MEV50 of ropivacaine 0.75% represents a 71% reduction in volume compared with neurostimulation techniques and a 14.7% reduction in volume compared with US-guided PSNB using the alternative perineural injection technique.

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.

Diabetic neuropathy increases stimulation threshold during popliteal sciatic nerve block

In India, the prevalence of diabetes mellitus neuropathy was reported to be as high as 30%. Eight percentage of the diabetic population suffer from foot ulceration and 1.8% have amputations. Popliteal nerve block can be potentially used for foot and ankle surgery with several advantages. To compare analgesic duration of an ultrasound (US)-guided popliteal sciatic nerve block between diabetics with neuropathy and nondiabetics without neuropathy. Participants were allocated into two groups for popliteal sciatic nerve blocks under US guidance. The primary outcome was the duration to onset of sensory and motor blockade. The secondary outcome was the duration to rescue analgesic and the visual analog scale scoring within 24 h. Hemodynamic outcomes were also monitored along with the above variables. It was observed that the onset of sensory blockade was faster in participants with diabetes mellitus with peripheral neuropathy as compared to the nondiabetic participants and the duration for onset of motor blockade in dorsiflexion was faster in diabetic patients as compared to the nondiabetic patients (17.48 ± 3.21 min). However, there was no significant changes when comparing the onset of duration to loss of plantar flexion, in diabetics (17.86 ± 2.29 min) versus in nondiabetics (18.51 ± 3.32 min). The duration for rescue analgesics was found to be longer in diabetic participants (13.19 ± 2.14 h) as compared to the nondiabetic participants (11.44 ± 1.86 h). No differences were observed in the hemodynamic changes and the complications associated with local anesthetics in either group. Diabetic patients with neuropathy have faster onset of blockade when compared to nondiabetic patients without neuropathy which may be due to the degenerative condition of the peripheral nerves in them. The hemodynamic parameters do not play a role in defining the outcome of the block.

The connective tissue layers that surround the sciatic nerve at the popliteal fossa are poorly defined. We present high-definition ultrasound images of the sciatic nerve, which were acquired during ultrasound-guided popliteal sciatic nerve block (SNB), that clearly demonstrate these fascial layers. Four patients undergoing hallux valgus surgery received an ultrasound-guided popliteal SNB using a high-definition ultrasound system. In the ultrasound images, the paraneural sheath was identified as a hyperechoeic fascial layer between the outer surface of the sciatic nerve (epineurium) and the epimysium of the surrounding muscles. The paraneural sheath was distinct from the epineurium, better delineated after the local anesthetic injection, and enveloped not only the sciatic nerve but also the common peroneal and tibial nerves separately. In the postblock sonograms, the local anesthetic was compartmentalized into 2 broad areas, that is, external (subepimyseal) and internal (subparaneural) to the paraneural sheath. The popliteal SNB was effective for surgical anesthesia in all 4 patients. We have demonstrated the paraneural sheath and the fascial compartments, that is, the "subepimyseal perineural compartment" and the "subparaneural compartment" that surround the sciatic nerve and act as conduits for local anesthetic spread during a popliteal SNB.