Minimum Effective Volume of Combined Lidocaine-Bupivacaine for Analgesic Subparaneural Popliteal Sciatic Nerve Block:

Cadaveric study investigating the femoral nerve-sparing volume for pericapsular nerve group (PENG) block

BACKGROUND

This cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90) required to stain the iliac bone between the anterior inferior iliac spine (AIIS) and the iliopubic eminence (IPE) while sparing the femoral nerve during the performance of pericapsular nerve group (PENG) block.

METHODS

In cadaveric hemipelvis specimens, the ultrasound transducer was placed in a transverse orientation, medial and caudal to the anterior superior iliac spine in order to identify the AIIS, the IPE and the psoas tendon. Using an in-plane technique and a lateral-to-medial direction, the block needle was advanced until its tip contacted the iliac bone. The dye (0.1% methylene blue) was injected between the periosteum and psoas tendon. Successful femoral-sparing PENG block was defined as the non-staining of the femoral nerve on dissection. Volume assignment was carried out using a biased coin design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure (ie, stained femoral nerve), the next one received a lower volume (defined as the previous volume with a decrement of 2 mL). If the previous cadaveric specimen had a successful block (ie, non-stained femoral nerve), the next one was randomized to a higher volume (defined as the previous volume with an increment of 2 mL), with a probability of b=1/9, or the same volume, with a probability of 1-b=8/9.

RESULTS

A total of 32 cadavers (54 cadaveric hemipelvis specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for femoral-sparing PENG block was estimated to be 13.2 mL (95% CI: 12.0 to 20.0). The probability of a successful response was estimated to be 0.93 (95% CI: 0.81 to 1.00).

CONCLUSION

For PENG block, the MEV90 of methylene blue required to spare the femoral nerve in a cadaveric model is 13.2 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in live subjects.

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

PURPOSE

To 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 METHODS

This 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.

RESULTS

All 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).

CONCLUSIONS

PSNB 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.

The Minimum Effective Concentration (MEC95) of different volumes of ropivacaine for ultrasound-guided caudal epidural block: a dose-finding study

BACKGROUND

Caudal epidural block (CEB) may be beneficial in anorectal surgery because its use may extend postoperative analgesia. This dose-finding study aimed to estimate the minimum effective anesthetic concentrations for 95% patients(MEC95) of 20 ml or 25 ml of ropivacaine in with CEB.

PATIENTS AND METHODS

In this double-blind, prospective study, the concentration of ropivacaine administered in 20 ml and 25 ml for ultrasound-guided CEB were determined using the sample up-and-down sequential allocation study design of binary response variables. The first participant was given 0.5% ropivacaine. Depending on whether a block was successful or unsuccessful, the concentration of local anesthesia was decreased or increased by 0.025% in the next patient. Every five minutes for 30 min, the sensory blockade using a pin-prick sensation at S3 dermatome compared to at T6 dermatome were evaluated every 5 min within 30 min. An effective CEB was defined as a a reduction of sensation at S3 dermatome and the existence of flaccid anal sphincter. Anesthesia was considered successful if the surgeon could perform the surgery without additional anesthesia. We determined the MEC50 using the Dixon and Massey up-and-down method and estimated the MEC95 using probit regression.

RESULTS

The concentration of ropivacaine administered in 20 ml for CEB ranged from 0.2% to 0.5%. Probit regression with a bias-corrected Morris 95% CI derived by bootstrapping showed an MEC50 and MEC 50 of ropivacaine for anorectal surgical anesthesia were 0.27% (95% CI, 0.24 to 0.31) and 0.36%(95% CI, 0.32 to 0.61). The concentration of ropivacaine administered in 25 ml for CEB ranged from 0.175 to 0.5. Probit regression with a bias-corrected Morris 95% CI derived by bootstrapping showed an MEC50 and MEC95 for CEB were 0.24% (95% CI, 0.19 to 0.27) and 0.32% (95% CI, 0.28 to 0.54).

CONCLUSION

With ultrasound-guided CEB, the MEC95 of 0.36% ropivacaine at 20 ml and 0.32% ropivacaine at 25 ml provide adequate surgical anesthesia/analgesia 95% of patients undergoing anorectoal surgery.

TRIAL REGISTRATION

Clinicaltrails.gov: Retrospectively registered (ChiCTR2100042954; Registration date:1/2, 2021).

Low-dose lidocaine attenuates fentanyl-induced cough: A double-blind randomized controlled trial

PURPOSE

The study aimed to determine the efficacy of lidocaine at different low doses to reduce fentanyl-induced cough (FIC).

METHODS

Three hundred twenty patients aged from 18 to 60 years with ASA I and II scheduled for general anesthesia were randomly assigned to 4 groups to obtain peripheral intravenous 0.9%NaCl (Group I), lidocaine 0.25 mg/kg (Group II), 0.5 mg/kg (Group III) or 1.0 mg/kg (Group IV) 2 min before 3 μg/kg of fentanyl intravenously in a prospective randomized controlled fashion. The primary result was incidence of cough among comparison groups. The secondary results included severity of cough, hemodynamic response and risk factors of FIC.

RESULTS

Thirty-two, 15, 13 and 11 patients (40, 18.8, 16.3 and 13.8%) presented incidence of cough in Groups I, II, III and IV, respectively (P < 0.05 Group I vs. II, III and IV). No significant difference was observed in the incidence and severity of cough among the lidocaine groups (P > 0.05). Multivariate analysis showed that age ≤ 40 years, nonsmoking and patients not receiving the prior lidocaine injection were risk factors of FIC (P = 0.007, 0.013 and 0.001, respectively).

CONCLUSION

The study implied intravenous lidocaine 0.25 mg/kg for 2 min before fentanyl injection was the most effective dose to suppress FIC and could be applied in daily practice. Patients aged less than 40 years and nonsmoking were risk factors of FIC, regardless of sex and underlying disease.

Cadaveric study investigating the phrenic-sparing volume for anterior suprascapular nerve block

BACKGROUND

This cadaveric study investigated the maximum effective volume of dye in 90% of cases (MEV90), required to stain the suprascapular nerve while sparing the phrenic nerve during the performance of an anterior suprascapular nerve block.

METHODS

In cadaveric neck specimens, using ultrasound guidance, the block needle was advanced until its tip was positioned underneath the omohyoid muscle next to the suprascapular nerve. The dye was injected in order to achieve circumferential spread around the latter. Successful phrenic-sparing suprascapular nerve block was defined as the non-staining of the phrenic nerve on dissection. Volume assignment was carried out using a Biased Coin Design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure (ie, stained phrenic nerve), the next one received a lower volume (defined as the previous volume with a decrement of 2 mL). If the previous cadaveric specimen had a successful block (ie, non-stained phrenic nerve), the next one was randomized to a higher volume (defined as the previous volume with an increment of 2 mL), with a probability of b=0.11, or the same volume, with a probability of 1 - b=0.89.

RESULTS

Thirty-one cadavers (56 cadaveric neck specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for phrenic-sparing anterior suprascapular nerve block was estimated to be 4.2 mL (95% CI 3.0 to 5.0 mL). The probability of a successful response was estimated to be 0.90 (95% CI 0.84 to 0.96).

CONCLUSION

For ultrasound-guided anterior suprascapular nerve block, the MEV90 of dye required to spare the phrenic nerve is 4.2 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in live subjects.

Cadaveric investigation of the minimum effective volume for ultrasound-guided suprainguinal fascia iliaca block

BACKGROUND

This cadaveric dose-finding study investigated the minimum effective volume of dye in 90% of cases (MEV90), required to stain the femoral, lateral femoral cutaneous and obturator nerves for ultrasound-guided suprainguinal fascia iliaca block (SIFIB).

METHODS

In cadaveric specimens of the lower limb, the block needle was advanced, medial to the anterosuperior iliac spine, until its tip was positioned between the internal oblique and iliacus muscles underneath the fascia iliaca. The dye was injected inside the fascia iliaca compartment. Volume assignment was carried out using a biased coin design, whereby the volume of dye administered to each cadaveric specimen depended on the response of the previous one. In case of failure, the next one received a higher volume (defined as the previous volume with an increment of 2.5 mL). If the previous cadaveric specimen had a successful block, the next one was randomized to a lower volume (defined as the previous volume with a decrement of 2.5 mL), with a probability of b=0.11, or the same volume, with a probability of 1-b=0.89. Success was defined as the staining of the femoral, lateral femoral cutaneous, and obturator nerves on dissection.

RESULTS

Thirty-six cadavers (60 cadaveric specimens) were included in the study. Using isotonic regression and bootstrap CI, the MEV90 for ultrasound-guided SIFIB was estimated to be 62.5 mL (95% CI 60 to 65).

CONCLUSION

For ultrasound-guided SIFIB, the MEV90 of dye required to stain the femoral, lateral femoral cutaneous and obturator nerves is 62.5 mL. Further studies are required to correlate this finding with the MEV90 of local anesthetic in human subjects.

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

Background

Intravenous (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.

Methods

Patients 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.

Results

Compared 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.

Conclusions

This 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.

Ultrasound-guided regional anaesthesia in foot and ankle surgery

The use of regional anaesthesia in foot and ankle surgery is becoming well recognised, particularly in patients who prefer to stay awake during the procedure and for better post-operative analgesia. Its use is ideal for patients with multiple co-morbidities, in whom general anaesthesia (GA) otherwise would could be challenging. The procedures performed with landmark/anatomical guidance alone carry a relatively higher risk of complications, risk of inadvertant injection into the intarvascualr space leadinf to local anaesthetic toxicity, the majority of which complications are caused by incorrect placement of the needle. Hence, ultrasound guidance is frequently used to minimise those risks. Although various regional anaesthetic techniques for foot and ankle surgery have been described, their comprehensive review is lacking. This manuscript aims to fulfil this void. The focus will be on the peripheral methods of regional anaesthesia including the plexus and single nerve blocks. Various techniques with their benefits and potential complications will be discussed. In addition, the evidence on the efficacy of an ultrasound-guided approach as well as its cost implications will be explored. There are significant considerations in deciding whether to implement this technique in routine clinical practice and this review aims to summarise the available literature to establish the evidence base behind it.

Fascia Iliaca Block Decreases Hip Fracture Postoperative Opioid Consumption: A Prospective Randomized Controlled Trial

OBJECTIVES

To determine the efficacy of a preoperative fascia iliaca compartment block in decreasing postoperative pain and improving functional recovery after hip fracture surgery.

DESIGN

Randomized prospective Level 1 therapeutic.

SETTING

Academic Level 1 trauma center.

PATIENTS

Geriatric patients with fractures of the proximal femur (neck, intertrochanteric, or subtrochanteric regions) were prospectively randomized into an experimental (A) or control (B) groups. Forty-seven patients met inclusion criteria, 23 randomized to the experimental group and 24 to the control group.

INTERVENTION

Patients randomized to the experimental group received an ultrasound-guided fascia iliaca compartment block administered by a board-certified anesthesiologist immediately before the initiation of anesthesia.

MAIN OUTCOME MEASUREMENTS

Primary outcome measure was postoperative pain medication consumption until postoperative day 3. Secondary outcomes included functional recovery and a study-specific patient-reported satisfaction survey assessed on postoperative day 3.

RESULTS

There was no significant difference in consumption of acetaminophen for mild pain, tramadol for moderate pain, or functional recovery between the 2 groups. There was a statistically significant decrease in morphine consumption (0.4 mg vs. 19.4 mg, P = 0.05) and increase in patient-reported satisfaction (31%, P = 0.01).

CONCLUSIONS

Preoperative fascia iliaca compartment block significantly decreases postoperative opioid consumption while improving patient satisfaction. We recommend the integration of this safe and efficacious modality into institutional geriatric hip fracture protocols as an adjunctive pain control strategy.

LEVEL OF EVIDENCE

Therapeutic Level II See Instructions for Authors for a complete description of levels of evidence.

3D ultrasound estimation of the effective volume for popliteal block at the level of division

Local anaesthetic injection between the tibial and commmon peroneal nerves within connective tissue sheath results in a predictable diffusion and allows for a reduction in the volume needed to achieve a consistent sciatic popliteal block. Using 3D ultrasound volumetric acquisition, we quantified the visible volume in contact with the nerve along a 5cm segment.

METHODS

We included 20 consecutive patients scheduled for bunion surgery. Ultrasound guided popliteal block was performed using a posterior, out of plane approach at the level of división of the sciatic nerve. Thirty ml of mepivacaine 1.5% and levobupivacaine 0.5% were slowly injected while assessing the injection pressure and the diffusion of the local anaesthetic. Volumetric acquisition was performed before and after the block to quantify the the volume of the sciatic nerve and the volume of the surrounding hypoechoic halo contained inside the connective tissue in a 5cm segment.

RESULTS

All blocks were successful within 20min after the injection. The total estimated volume contained inside the common connective tissue sheath was 6.8±2.6cm³. Of this, the volume of the halo sorrounding the nerve was 4.4±1.7cm³ and the volume inside the sciatic nerve was 2.4±1.7cm³.

CONCLUSIONS

The volume of local anaesthetic in close contact with the sciatic nerve can be estimated by volumetric acquisition. Our results suggest that the effective volume of local anaesthetic needed for a successful sciatic popliteal block could be reduced to less than 7ml.

Efficacy of ultrasound-guided fascia iliaca compartment block after hip hemiarthroplasty: A prospective, randomized trial

BACKGROUND

The fascia iliaca compartment block (FICB) provides an analgesic effect in patients with femur fractures. However, the postoperative pain after hip surgery is different from that after femur fracture, because of the difference in the degree and location of tissue trauma. Whether FICB provides effective postoperative analgesia in patients undergoing total hip arthroplasty is not well understood. Moreover, there is no prospective randomized study to evaluate FICB as a postoperative analgesia in hemiarthroplasty. Therefore, we performed a randomized and prospective study to determine the effect of FICB after hemiarthroplasty. The objective of this study was to compare the opioid consumption between patients who received intravenous patient-controlled analgesia (PCA) with and without FICB.

METHODS

Twenty-two patients aged 70 to 90 years who underwent bipolar hemiarthroplasty for femoral neck fracture were recruited and allocated randomly into 2 groups: FICB group (n = 11) and Non-FICB group (n = 11). All patients received spinal anesthesia with 10 mg of 0.5% hyperbaric bupivacaine. After surgery, the FICB was conducted using a modified technique with 0.2% ropivacaine (40 mL) under ultrasonographic guidance, and the intravenous PCA was administered to patients in both groups in the separate block room. The PCA was set up in the only bolus mode with no continuous infusion. The visual analog scale (VAS) and the opioid consumption were noted at 4, 8, 12, 24, and 48 hours postoperatively.

RESULTS

The VAS was similar in both groups. The fentanyl requirement at 4, 8, and 12 hours was low in the FICB group. The total amount of fentanyl required in the first 24 hours was 246.3 μg in the FICB group and 351.4 μg in the Non-FICB group. No patient developed any residual sensory-motor deficit during the postoperative period. Patients in the Non-FICB group had nausea (n = 2), and pruritus (n = 1), and 1 patient had nausea in the FICB group during postoperative 2 days.

CONCLUSION

The FICB has a significant opioid-sparing effect in first 24 hours after hemiarthroplasty. This suggests that FICB is an effective way for multimodal analgesia in hip surgery.

Minimum effective local anesthetic volume for surgical anesthesia by subparaneural, ultrasound-guided popliteal sciatic nerve block: A prospective dose-finding study

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.

Efficacy and safety of bupivacaine versus lidocaine in local anesthesia of the nasopharynx: A meta-analysis

PURPOSE

To assess the efficacy and safety of bupivacaine compared with lidocaine in local anesthesia of nasopharynx through meta-analysis.

METHODS

A number of medical literature data bases were searched electronically. Relevant journals and references of included studies were manually searched. Two reviewers independently performed data extraction and quality assessment.

RESULTS

Four studies were included. Visual analog scale (VAS) scores, acceptable discomfort, and bleeding scores were analyzed for bupivacaine versus lidocaine. When considering the VAS scores, bupivacaine as a local anesthetic agent was better than lidocaine in controlling the pain of postoperative patients (p < 0.00001). From VAS scores of patients for transnasal fiberoptic nasopharyngolaryngoscopic examination that was performed to evaluate upper airway structures, lidocaine was found to be better at pain management in patients who underwent transnasal endoscopic examination (p < 0.00001). However, when analyzing the acceptable discomfort of patients who underwent upper gastrointestinal endoscopy, which serves as a valuable tool to evaluate upper gastrointestinal structures, the patients in the bupivacaine group demonstrated a higher acceptable discomfort than the patients in the lidocaine group (p = 0.008). With regard to the bleeding scores of the patients with nasal surgery, lidocaine was better at bleeding in postoperative patients compared with bupivacaine (p = 0.0007). These results indicated that bupivacaine showed better pain control of postoperative patients and acceptable discomfort in patients with upper gastrointestinal endoscopy. Lidocaine had a significantly increased ability the pain of patients with transnasal fiberoptic nasopharyngolaryngoscopic examination and bleeding in postoperative patients. No systemic adverse events were reported.

CONCLUSION

Bupivacaine was found to have better promotion to pain control than did lidocaine for the patients after nasal surgery. Lidocaine had a significantly increased inhibition of bleeding in these postoperative patients; however, the efficacy between bupivacaine and lidocaine was unclear for the patients who had transnasal endoscopic examinations.

Dose effect of local anesthetics on analgesic outcomes for the transversus abdominis plane (TAP) block in children: a randomized, double-blinded, clinical trial

BACKGROUND

Current knowledge on local anesthetic dosage for the TAP block in pediatric patients is very limited.

OBJECTIVE

To evaluate the effect of two escalating local anesthetic doses on postsurgical analgesic outcomes in children receiving a TAP block.

METHODS

The study was a prospective, randomized, double-blinded, clinical trial. Children (<8 years) were randomized to one of the two intervention groups: TAP block with bupivacaine at a dose of 2.5 mg · kg(-1) or 1.25 mg · kg(-1). Analgesic outcomes included pain scores in the postanesthesia care unit (PACU), time to analgesic requirement and total number of analgesic requirements.

RESULTS

Thirty-six patients were recruited in the study. Pain scores in PACU were not different between study groups. The total number of analgesic dosage required in 24 h after surgery was higher in the lower dose group, median (IQR) of 4 (3 to 5) compared to 2.5 (1.5 to 3) in the greater dose group, P = 0.03. There was a clinically but not statistically significant difference in the time to first analgesic requirement in the 2.5 mg · kg(-1) group, median (IQR) of 248 (130 to 367) minutes compared to 146 (95 to 261) minutes in the 1.25 mg · kg(-1) dose group, P = 0.15.

CONCLUSIONS

The use of higher local anesthetic doses for the TAP block in children does not provide benefits on early pain scores but seems to improve analgesic duration and decrease the need for additional analgesics over 24 h after surgery. The use of higher, but yet safe, local anesthetic dosages for TAP blocks is a viable strategy to improve analgesia in children.

Dose-finding methodology for peripheral nerve blocks

Dose-finding studies enable the successful conduct of peripheral nerve blocks by ensuring the administration of appropriate doses of local anesthetic. However, the optimal dose-finding methodology remains ambiguous. In this research methodology article, we set out to review the basic aspects pertaining to dose-response curves (graded vs quantal), the pharmacodynamic indices required by dose-finding studies, the properties of different dose-finding methods (sigmoidal dose-response curve analysis, Dixon-Mood method, Biased Coin Design, and Bayesian analysis), as well as strategies and recommendations for future research.