Minimum effective concentration of ropivacaine for ultrasound-guided transmuscular quadratus lumborum block in total hip arthroplasty: a randomized clinical trial

OBJECTIVE

This trial aimed to identify the Minimum Effective Concentration (MEC90, defined as the concentration which can provide successful block in 90% of patients) of 30 mL ropivacaine for single-shot ultrasound-guided transmuscular Quadratus Lumborum Block (QLB) in patients undergoing Total Hip Arthroplasty (THA).

METHODS

A double-blind, randomized dose-finding study using the biased coin design up-and-down sequential method, where the concentration of local anesthetic administered to each patient depended on the response from the previous one. Block success was defined as a Numeric Rating Scale (NRS) score during motion ≤ 3 at 6 hours after arrival in the ward. If the block was successful, the next subject received either a 0.025% smaller dose (probability of 0.11) or the same dose (probability of 0.89); otherwise, the next subject received a 0.025% higher ropivacaine concentration. MEC90, MEC95 and MEC99 were estimated by isotonic regression, and the corresponding 95% Confidence Intervals (95% CIs) were calculated by the bootstrapping method.

RESULTS

Based on the analysis of 52 patients, MEC90, MEC95, and MEC99 of ropivacaine for QLB were estimated to be 0.352% (95% CI 0.334-0.372%), 0.363% (95% CI 0.351-0.383%), and 0.373% (95% CI 0.363-0.386%). The concentration of ropivacaine at 0.352% in a volume of 30 ml can provide a successful block in 90% of patients.

CONCLUSIONS

For ultrasound-guided transmuscular QLB in patients undergoing THA, 0.352% ropivacaine in a volume of 30 ml can provide a successful block in 90% of patients. Further dose-finding studies and large sample size are required to verify the concentration.

Relationship Between Gender, Age, BMI and Side of Body on the Size and Position of Nerves of the Brachial Plexus in Axilla: Pilot Study

Background and Objectives

Studies demonstrate variations in the size and position of the nerves in the brachial plexus. The objective of this pilot study was to determine the effect of age, gender, BMI and side of body on the size and position of these nerves and to determine the feasibility of a further study.

Methods

Twenty healthy volunteers were recruited. The ultrasound position of the nerves was confirmed by a dynamic scan. The size of the nerves was calculated using the freehand calliper tool. A graph was designed to study the position of the nerves. ImageJ was used to analyse the position of the nerves. Student's t-tests were carried out to compare the gender and side of arm with the size of the nerve. Pearson's correlation coefficients were calculated to determine the correlation between BMI and age with the size of the nerves. The position of the nerves was compared between male and female, and left and right sides of the body.

Results

The mean size of the median nerve, musculocutaneous nerve, radial nerve and ulnar nerve was 0.099, 0.032, 0.179 and 0.076 cm2 (males) and 0.091, 0.022, 0.128 and 0.026 cm2 (females), respectively. There were significant differences between the size of nerves and gender in the musculocutaneous, radial and ulnar nerves (P <0.05). The correlations between the sizes of the nerves with BMI and age were not significant. The position of the radial nerves was found to be variable within the same genders and between males and females. The position of the nerves was variable between the left and right hand side.

Conclusion

The position and size of brachial plexus branches in axilla is very variable. This pilot study highlights the need for further research with larger sample sizes to fully understand the extent and implication of this variability.

A Randomized Controlled Trial: Comparison of 4% Articaine versus 0.5% Bupivacaine for Ambulatory Orthopedic Surgery under Supraclavicular Block

BACKGROUND

Articaine has been used in many dental and ophthalmic outpatient procedures. In the era of ultrasound-guided regional techniques, we searched for short and potent local anesthetic for patients undergoing ambulatory upper limb procedures. However, studies about articaine efficacy in brachial plexus block are limited. In this study, we compared its safety and efficacy against bupivacaine as a commonly used anesthetic agent for ultrasound-guided supraclavicular brachial plexus block.

METHODS

This randomized prospective study was performed at Ain Shams University Hospital from January to March 2020. A total of 117 patients aged 20 to 60 years, with the American Society of Anesthesiologists physical status I and II, were enrolled in the study. Patients were randomly allocated into two groups: in group A, patients received 30 ml articaine 2%, and in group B, patients received 30 ml of bupivacaine 0.5%. We measured motor and sensory block duration as a primary outcome. Other secondary outcomes such as onset of block, duration of analgesia, patient satisfaction, and time to home discharge readiness were also measured.

RESULTS

We analyzed data collected from 97 patients. The motor block duration was significantly shorter in group A (165.73 ± 20.33 min) than in group B (220.27 ± 37.73 min). The onset of motor block was faster in group A (8.73 ± 4.33 min), and the postoperative VAS score was lower in group B. Patients in group A achieved an earlier home discharge of 289.67 ± 2.73 min.

CONCLUSION

Earlier resolution of articaine block makes it more favorable than bupivacaine for ambulatory surgery. This trial is registered with (NCT04189198).

High-Volume, Low-Concentration Intraperitoneal Bupivacaine Study in Emergency Laparoscopic Cholecystectomy: A Double-Blinded, Prospective Randomized Clinical Trial

Background. Laparoscopic cholecystectomy (LC) often results in postoperative pain, especially in the abdomen. Intraperitoneal local anesthesia (IPLA) reduces pain after LC. Acute cholecystitis-associated inflammation, increased gallbladder wall thickness, dissection difficulties, and a longer operative time are several reasons for assuming a benefit in pain scores in urgent LC with IPLA application. The aim was to determine the postoperative analgesic efficacy of high-volume, low-dose intraperitoneal bupivacaine in urgent LC. Materials and Methods. Fifty-seven patients who were American Society of Anesthesiologists physical status I or II were randomly assigned to receive either normal saline (control group) or intraperitoneal bupivacaine (test group) at the beginning or end of urgent LC. The primary outcome was the postoperative pain score of the Visual Analogue Scale (VAS). The secondary outcomes included Visual Rating Prince Henry Scale (VRS), patient satisfaction, and analgesic consumption. Results. Postoperative VAS scores at the first and fourth hours were significantly lower in the test group than in the control group (P < .001). Postoperative VRS scores at the first, fourth, and eighth hours were significantly lower in the test group than in the control group (P < .001, P = .002, P = .004, respectively). Analgesic use was significantly higher in the control group at the first postoperative hour (P < .001). Shoulder pain was significantly lower, and patient satisfaction was significantly higher in the test group relative to the control group (both P < .001). Conclusion. High-volume, low-concentration intraperitoneal bupivacaine resulted in better postoperative pain control and reduced incidence of shoulder pain and analgesic consumption in urgent LC.

A prospective randomised controlled study for evaluation of high-volume low-concentration intraperitoneal bupivacaine for post-laparoscopic cholecystectomy analgesia

BACKGROUND AND AIMS

Low-volume high-concentration bupivacaine irrigation of the peritoneal cavity has been reported to be ineffective for short-term analgesia after laparoscopic cholecystectomy (LC). This study was conducted to evaluate the effectiveness of intraperitoneal instillation of high-volume low-concentration bupivacaine for post-operative analgesia in LC.

METHODS

Sixty patients undergoing LC were included in this prospective, double-blind, randomised study. Patients were divided into two (n = 30) groups. In Group S, intraperitoneal irrigation was done with 500 ml of normal saline. In Group B, 20 ml of 0.5% (100 mg) bupivacaine was added to 480 ml of normal saline for intraperitoneal irrigation during and after surgery. Post-operative pain was assessed by numeric pain rating scale (NRS) at fixed time intervals. Duration of analgesia (DOA), total rescue analgesic requirement (intravenous tramadol), presence of shoulder pain, nausea and vomiting were recorded for the initial 24 h post-operatively.

RESULTS

Mean DOA in Group S was 0.06 ± 0.172 h (3.6 ± 10.32 min) and that in Group B was 19.35 ± 8.64 h (P = 0.000). Cumulative requirement of rescue analgesic in 24 h in Group S was 123.33 ± 43.01 mg and that in Group B was 23.33 ± 43.01 mg (P = 0.000). There was no significant difference in incidence of shoulder pain, nausea and vomiting between the groups.

CONCLUSION

High-volume low-concentration of intraperitoneal bupivacaine significantly increases post-operative DOA and reduces opioid requirement after LC.

Analgesic efficacy of intraperitoneal administration of bupivacaine in cats

Objectives

The aim of this study was to evaluate the analgesic efficacy of intraperitoneal (IP) bupivacaine in cats undergoing ovariohysterectomy (OVH).

Methods

Forty-five cats were included in a randomized, prospective, blinded study after owners’ written consent was obtained. The anesthetic protocol included acepromazine–buprenorphine–propofol–isoflurane. A ventral midline incision was made and cats (n = 15/group) were administered either IP saline 0.9% (negative and positive control groups; NG and PG, respectively) or IP bupivacaine (2 mg/kg; bupivacaine group; BG). Cats in the PG received meloxicam (0.2 mg/kg SC). An OVH was performed and postoperative pain was evaluated using a dynamic interactive visual analog scale (DIVAS), the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociceptive thresholds (MNT) for up to 8 h after the end of surgery. Postoperative sedation was evaluated using DIVAS. Rescue analgesia was provided with buprenorphine and/or meloxicam. Repeated measures linear models and a Cochran–Mantel–Haenszel test were used for statistical analysis ( P <0.05).

Results

There was a significant effect of treatment on the number of times rescue analgesia was administered ( P = 0.002) (PG, n = 2, 13%; NG, n = 12, 80%; BG, n = 4, 27%) with the number of rescues being higher in the NG group than in the PG ( P = 0.0004) and BG ( P = 0.02) groups. The DIVAS, MCPS and MNT were significantly different when compared with baseline values at different time points; however, data were not significantly different among groups.

Conclusions and relevance

Treatments PG and BG produced similar analgesia in terms of pain scores, number of times rescue analgesia was administered and MNT. Based on rescue analgesia, IP administration of bupivacaine provides analgesia in cats after OVH.

Lack of Sex Difference in Minimum Local Analgesic Concentration of Ropivacaine for Ultrasound-Guided Supraclavicular Brachial Plexus Block

Background

Sex differences, which may be an important variable for determining anesthetic requirements, have not been well investigated in the aspect of local anesthetic. This investigation aimed to compare the minimum local analgesic concentration (MLAC) of ropivacaine for ultrasound-guided supraclavicular brachial plexus block (US-SCB) between men and women.

Material/Method

Patients aged 18–45 years undergoing elective forearm, wrist, or hand surgeries under US-SCB were divided into 2 groups according to sex. The initial concentration was 0.375% ropivacaine 20 mL and the concentration for the next patient was determined by the up-down technique at 0.025% intervals. Success was defined as the absence of any pain in response to a pinprick in the region of all 4 terminal nerves and the skin incision within 45 min. The primary outcome was the MLAC of ropivacaine, which was estimated by the Dixon and Massey method. The analgesia duration, which was defined as the time from the end of the US-SCB injection to the time of feeling discomfort and need for additional analgesics, was observed for each patient.

Results

The MLAC of ropivacaine 20 mL for US-SCB was 0.2675% (95% confidence interval [CI], 0.2512–0.2838%) in men and 0.2675% (95% CI, 0.2524–0.2826%) in women. There was no significant difference in MLAC or the analgesia duration between the 2 groups (P>0.05).

Conclusions

We found no significant sex-related differences in MLAC or analgesia duration of ropivacaine for US-SCB.

Articaine and mepivacaine buccal infiltration in securing mandibular first molar pulp anesthesia following mepivacaine inferior alveolar nerve block: A randomized, double-blind crossover study

Aims:

A crossover double-blind, randomized study was designed to explore the efficacy of 2% mepivacaine with 1:100,000 adrenaline buccal infiltration and 4% articaine with 1:100,000 adrenaline buccal infiltration following 2% mepivacaine with 1:100,000 adrenaline inferior alveolar nerve block (IANB) for testing pulp anesthesia of mandibular first molar teeth in adult volunteers.

Materials and Methods:

A total of 23 healthy adult volunteers received two regimens with at least 1-week apart; one with 4% articaine buccal infiltration and 2% mepivacaine IANB (articaine regimen) and another with 2% mepivacaine buccal infiltration supplemented to 2% mepivacaine IANB (mepivacaine regimen). Pulp testing of first molar tooth was electronically measured twice at baseline, then at intervals of 2 min for the first 10 min, then every 5 min until 45 min postinjection. Anesthetic success was considered when two consecutive maximal stimulation on pulp testing readings without sensation were obtained within 10 min and continuously sustained for 45 min postinjection.

Results:

In total, the number of no sensations to maximum pulp testing for first molar teeth were significantly higher after articaine regimen than mepivacaine during 45 min postinjection (267 vs. 250 episodes, respectively, P < 0.001), however, both articaine and mepivacaine buccal infiltrations are equally effective in securing anesthetic success for first molar pulp anesthesia when supplemented to mepivacaine IANB injections (P > 0.05). Interestingly, volunteers in the articaine regimen provided faster onset and longer duration (means 2.78 min, 42.22 min, respectively) than mepivacaine regimen (means 4.26 min, 40.74 min, respectively) for first molar pulp anesthesia (P < 0.001).

Conclusions:

Supplementary mepivacaine and articaine buccal infiltrations produced similar successful first molar pulp anesthesia following mepivacaine IANB injections in volunteers. Articaine buccal infiltration produced faster onset and longer duration than mepivacaine buccal infiltration following mepivacaine IANB injections.

Comparison of speed of action and injection discomfort of 4% articaine and 2% mepivacaine for pulpal anesthesia in mandibular teeth: A randomized, double-blind cross-over trial

Objective:

To compare the injection pain and speed of local anesthetic effect induced by tissue infiltration of mepivacaine 2% with epinephrine 1:100,000 versus articaine 4% with epinephrine 1:100,000 in securing mandibular first molar pulp anesthesia.

Materials and Methods:

Totally, 25 patients were recruited in a crossover, randomized, double-blind study. Each subject received injections of mepivacaine 2% with epinephrine 1:100,000 as inferior alveolar nerve block (IANB) supplemented with either articaine 4% with epinephrine 1:100,000 (septocaine) or mepivacaine 2% buccal infiltration (BI) injection on two visits. The time of first numbness to associated lip, tongue and tooth was recorded by asking the participant directly and using electrical pulp tester. Anesthetic success was considered when two consecutive maximal stimulation on pulp testing readings without sensation. The patients rated the pain of infiltration using a 100 mm visual analog scale immediately after receiving each injection. The pain scores were compared using the paired t-test.

Results:

There were significant differences in the meantime of first numbness to associated lip and tooth of volunteers between mepivacaine and articaine BI groups P = 0.03 and 0.002. Volunteers in articaine group recorded earlier lip and teeth numbness than those in mepivacaine group. There were significant differences between the mean pain scores for volunteers in the post IANB and postbuccal injection groups (t-test: P <0.001). Mepivacaine IANB injection was significantly more painful than articaine/mepivacaine buccal injection.

Conclusions:

About 4% articaine was faster than 2% mepivacaine (both with 1:100,000 adrenaline) in anesthetizing the pulps of lower molar teeth after BIs. Earlier lip and teeth numbness were recorded in articaine group. Articaine and mepivacaine BIs were more comfortable than mepivacaine IANB injections.

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.