Buffered lidocaine and bupivacaine mixture - the ideal local anesthetic solution?

Efficacy of Sodium Bicarbonate-Buffered Local Anesthetic Solution in Cases Requiring Bilateral Maxillary Premolar Orthodontic Extraction: A Comparative Split-Mouth Study

Aims and objectives This study was carried out to evaluate the efficacy of 8.4% sodium bicarbonate-buffered local anesthetic solution and conventional local anesthetic in patients requiring bilateral maxillary orthodontic extractions in terms of pain on injection, onset of action, and duration of action. Methods 102 patients requiring bilateral maxillary orthodontic extractions were included in the study. Buffered local anesthetic was administered on one side while conventional local anesthesia (LA) was administered on the other side. Pain on injection was measured using a visual analogue scale, while onset of action was measured by probing the buccal mucosa after 30 seconds of administration and duration of action was measured by the time after which the patient experienced pain or took a rescue analgesic. The data was statistically analyzed to determine the significance. Results The pain during injection was found to be lesser at sites where buffered local anesthetic was administered (mean visual analogue scale (VAS) score = 2.4) as compared to conventional local anesthetic (mean VAS score = 3.9). The onset of action was faster with buffered local anesthetic (mean value = 62.3 seconds) as compared to conventional local anesthetic (mean value = 157.16 seconds). Lastly, the duration of action was found to be longer for buffered local anesthetic group (mean value = 225.65 minutes) as compared to conventional local anesthetic (mean value = 187 minutes). Conclusion 8.4% sodium bicarbonate-buffered local anesthetic was found to be more efficient than conventional local anesthetic in terms of reduction in pain on injection as well as faster onset and longer duration of action.

The Impact of Body Mass Index on Local Anaesthetic Inguinal Hernia Repair

BACKGROUND

Open mesh repair of inguinal hernia is acceptable and can be performed under local anaesthesia (LA). Individuals with high BMI (Body Mass Index) have often been excluded from LA repairs for varying reasons including safety concerns. Open repair of unilateral inguinal hernia (UIH) amongst individuals with different BMI groups was studied. Its safety profile was investigated using LA volume and length of operation (LO) as endpoints. Operative pain and patient satisfaction were also evaluated.

PATIENTS AND METHODS

A total of 438 adult patients were studied having excluded underweight patients, those requiring any additional intra-operative analgesia, multiple procedures, or records with incomplete data. Operative pain, patient satisfaction, LO and LA volume were retrospectively studied from the existing data from clinical and operative notes.

RESULTS

It was a predominantly male population (93.2% males) with an age range of 17-94 years peaking in the 60-69 years age group. BMI ranged 19-39 kg/m² with BMI above normal at 62.8%. LO was 13-100 minutes (average 37 mins {SD = 12}) utilising an average LA volume of 45 ml (SD = 11) per patient. Across BMI groups, no significant difference in LO (P = 0.168) or patient satisfaction (P = 0.388) was seen. Although LA volume (P = 0.011) and pain score (P<0.001) demonstrated statistically significant differences, these did not appear to be clinically relevant. Over 90% in each BMI group experienced mild or no pain and with severe pain reported in only one patient in the entire population. Overall, LA volume required per patient was low and dosage was safe in all BMI groups with significant proportion (89%) of patients evaluated for satisfaction rating their experience ≥ 90 out of 100.

CONCLUSION

LA repair is safe and well tolerated irrespective of BMI. BMI is not a viable reason for exclusion of obese/overweight individuals from LA repair.

A Comparative Study to Evaluate the Anesthetic Efficacy of Buffered Versus Non-buffered 2% Lidocaine During Inferior Alveolar Nerve Block

BACKGROUND

The study aimed to compare the clinical efficacy, safety, and acceptability of buffered lidocaine (8.4% sodium bicarbonate and 2% lidocaine with 1:80,000 adrenaline) versus non-buffered lidocaine (2% lidocaine with 1:80,000 adrenaline) during inferior alveolar nerve block.

MATERIALS AND METHODS

Fifty patients who required bilateral extractions in a single arch were included in this study. One hundred extractions were carried out, and all of the patients had nerve blocks during the procedure. We also took note of the patient's pain level as measured on a visual analog scale, as well as the start of the action, duration of postoperative analgesia, and occurrence of any problems. The duration of anesthesia was assessed by the feeling of numbness and the first sign of pain.

RESULT

All the patients in both study groups reported subjective numbness of the lips and tongue. The depth of anesthesia was evaluated by pain and comfort during the procedure with a visual analog scale and showed no significant difference between the two groups. The onset of action for the pterygomandibular nerve block was 1.240.31 minutes (buffered) and 1.710.51 minutes (non-buffered). When compared, the duration of anesthesia was 327.18102.98 minutes (buffered) and 129.0826.85 minutes (non-buffered).

CONCLUSION

This study concludes that the buffered solution has a faster onset of action than the non-buffered solution. Both solutions exhibit similar intraoperative efficacy. The duration of postoperative anesthesia was prolonged with buffering. Buffering also reduced pain scores during the early postoperative period.

Interventional Radiology Regional Anesthesia Approaches for Intra- and Postprocedural Pain Control

Effective pain control enables procedural success and improved patient satisfaction in interventional radiology. Regional anesthesia techniques are now established for intraoperative and postoperative anesthesia during major surgery, and interventional radiologists (IRs) can readily apply these injections for intraprocedural nerve blocks that can reduce anesthetic requirements and ensure durable analgesia postprocedure. Moreover, IR is poised to advance this field with novel blocks unique to IR needs and by blocking deep plexi safely reachable with CT guidance (e.g., hepatic hilar plexus, aorticorenal plexus blocks). This report aims to provide a succinct IR-directed primer for image-guided nerve blocks usable in the interventional radiology suite.

Buffered lidocaine for paracervical blocks in first-trimester abortions: a randomized controlled trial

Objective

The objective was to evaluate if buffered lidocaine decreases injection pain as compared to plain lidocaine for paracervical blocks during first-trimester outpatient surgical abortions.

Study design

We conducted a randomized, double-blind, placebo-controlled trial among women undergoing outpatient uterine aspiration of a first-trimester pregnancy or an early pregnancy loss. Subjects received a paracervical block with either lidocaine 1% 20 mL or lidocaine 1% 18 mL plus sodium bicarbonate 8.4% 2 mL. The primary outcome was pain from injection of the paracervical block measured on a 100-mm visual analog scale (VAS). Secondary outcomes included pain after cervical dilation, uterine aspiration and overall satisfaction with pain control. Scores were compared using the Mann–Whitney U test. We aimed to detect a 15-mm difference in pain from injection of the paracervical block.

Results

From May 2017 to October 2018, 48 women received plain lidocaine and 50 women received buffered lidocaine. Groups were similar in demographics. We found no clinically or statistically meaningful difference in pain when evaluating median VAS scores for paracervical block injection between the buffered and plain lidocaine [30.0 (interquartile range (IQR) 15.3–64.5); 44.5 (IQR 18.3–65), respectively, p = .32]. We found no difference in secondary outcomes between buffered and plain lidocaine.

Conclusion

Buffered lidocaine for paracervical blocks in first-trimester outpatient surgical abortions does not decrease injection pain as compared to plain lidocaine.

Implications statement

Buffering the paracervical block in first-trimester outpatient surgical abortions does not decrease injection pain as compared to plain lidocaine, nor does it increase patient satisfaction. Eliminating sodium bicarbonate allows for a more cost-effective and readily available solution for paracervical blocks.

Comparison of bupivacaine alone and in a combination with lidocaine for caudal block in patients undergoing circumcision: A historical cohort study

OBJECTIVE

Optimal analgesia following ambulatory surgery is an important matter in patient satisfaction, and it reduces unnecessary hospital admissions. This study investigated whether a caudal block with bupivacaine alone or in a combination with lidocaine can alter postoperative pain scores, complications, and peroperative and postoperative analgesic consumption.

MATERIAL AND METHODS

This is a retrospective study that included children who underwent elective circumcision surgery under general anesthesia and caudal analgesia between January and June 2018. Among the 103 children, 17 cases were not analyzed due to an unsuccessful caudal block and procedures simultaneously underwent another operation unrelated to circumcision. We divided the study participants into two groups according to the type of local anesthetic applied: 0.5 mL/kg 0.25% bupivacaine (Group B) and 0.5 mL/kg 0.25% bupivacaine + 3 mg/kg 1% lidocaine (Group BL) caudally.

RESULTS

Pain scores were similar between these groups and remained in the mild-to-moderate range throughout the hospitalization (p>0.05). There were significant differences regarding the rescue analgesic use, first micturition, and mobilization times (p<0.001). In addition, we applied the multivariable logistic regression for fentanyl consumption adjusted for first mobilization and micturition time, unlike mobilization, a significantly increased risk for postoperative delayed micturition (OR, 1.06; 95% CI, 1.0-1.12; p=0.038) was found with intra-operative intravenous fentanyl use.

CONCLUSION

Our results suggest that the caudal block with a lidocaine+bupivacaine combination decreases rescue analgesic consumption at day-case surgery. In circumcision procedures, the caudal block is an effective and safe analgesic method for intraoperative and postoperative pain control with no side effects. This trial was registered at Clinicaltrals.gov, NCT03911648.

A physiological assessment of patient pain during surgery with wide-awake local anesthesia

Purpose

Patients receiving surgery with wide-awake local anesthesia typically report little or no intraoperative pain. However, self-report assessments of pain are susceptible to bias. In the present study, patient self-report ratings were supplemented with objective physiological measures of electrodermal activity.

Methods

Fifteen patients receiving forefoot surgery using wide-awake local anesthesia were recruited. Pain ratings and skin conductance responses were acquired during the initial anesthetic injection (into unanesthetized tissue), during a follow-up anesthetic injection (into anesthetized tissue), and during five intraoperative procedures.

Results

The highest ratings of self-reported pain coincided with the initial anesthetic injection, and pain ratings were similarly low at all remaining measurement points. Fourteen patients reported no pain beyond the initial injection, whereas one patient reported minimal pain during two intraoperative procedures. Skin conductance data were consistent with pain ratings such that responses to the initial injection were significantly larger than responses at any subsequent measurement point.

Conclusion

These results provide further evidence that patients experience little or no pain during surgery with wide-awake local anesthesia.

Subcutaneous Injection of Drugs: Literature Review of Factors Influencing Pain Sensation at the Injection Site

The subcutaneous administration route is widely used to administer different types of drugs given its high bioavailability and rapid onset of action. However, the sensation of pain at the injection site might reduce patient adherence. Apart from a direct effect of the drug itself, several factors can influence the sensation of pain: needle features, injection site, volume injected, injection speed, osmolality, viscosity and pH of formulation, as well as the kind of excipients employed, including buffers and preservatives. Short and thin needles, conveniently lubricated and with sharp tips, are generally used to minimize pain, although the anatomic injection site (abdomen versus thigh) also affects the sensation of pain. Large subcutaneous injection volumes are associated with pain. In this sense, the maximum volume generally accepted is around 1.5 ml, although volumes of up to 3 ml are well tolerated when injected in the abdomen. Injected volumes of up to 0.5–0.8 ml are not expected to increase substantially the pain produced by the needle insertion. Ideally, injectable products should be formulated as isotonic solutions (osmolality of about 300 mOsm/kg) and no more than 600 mOs/kg have to be used in order to prevent pain. A pH close to the physiological one is recommended to minimize pain, irritation, and tissue damage. Buffers are frequently added to parenteral formulations to optimize solubility and stability by adjusting the pH; however, their strength should be kept as low as possible to avoid pain upon injection. The data available recommend the concentration of phosphate buffer be limited to 10 mM and that the concentration of citrate buffer should be lower than 7.3 mM to avoid an increased sensation of pain. In the case of preservatives, which are required in multiple-dose preparations, m-cresol seems to be more painful than benzyl alcohol and phenol.

Funding: Sandoz SA.

Enhancement of Viable Adipose-Derived Stem Cells in Lipoaspirate by Buffering Tumescent with Sodium Bicarbonate

Background:

Fat grafting is a growing field within plastic surgery. Adipose-derived stem cells (ASCs) and stromal vascular fracture (SVF) may have a role in fat graft survival. Our group previously demonstrated a detrimental effect on ASC survival by the lidocaine used in tumescent solution. Sodium bicarbonate (SB) buffers the acidity of lidocaine. The purpose of this study was to determine whether SB buffering is a practical method to reduce ASC and SVF apoptosis and necrosis seen with common lidocaine-containing tumescent solution.

Methods:

Human patients undergoing bilateral liposuction for any indication were included in this study. An internally controlled, split-body design was utilized. Tumescent liposuction on one side of the body was conducted with tumescent containing lidocaine. On the opposite side, liposuction was conducted by adding SB to the tumescent. Tumescent solution and lipoaspirate pH were measured. Lipoaspirate from each side was processed for SVF isolation and ASC culture. The number of viable ASCs was counted and SVF apoptosis/necrosis was examined.

Results:

The pH of the SB-buffered tumescent was significantly higher than that of the standard tumescent, an effect also seen in the lipoaspirate. Adipose-derived stem cell survival in the SB-buffered lipoaspirate was approximately 53% higher. However, there was no significant difference in SVF apoptosis and necrosis between the groups.

Conclusions:

The acidic standard tumescent solution commonly used in liposuction diminishes ASC viability from lipoaspirates. Sodium bicarbonate buffering tumescent solution can enhance ASC viability, but does not affect SVF apoptosis and necrosis. We recommend buffering tumescent with SB to potentially improve fat graft take. Our findings advocate for further research investigating mechanisms and optimal harvest techniques that maximize SVF/ASC survival and the clinical effect on overall fat graft viability.

Is amalgamated ligno-bupivacaine an answer to complicated minor oral surgical anesthesia? A randomized split-mouth double-blind clinical trial

PURPOSE

The purpose of this study was to find a suitable anesthetic combination for complicated and protracted minor oral surgical procedures.

METHODS

Fifty patients with bilaterally impacted deep-seated mandibular third molars were included in this study and randomly divided on the basis of anesthetic used into two groups. Group A received 2% lignocaine with 1:200,000 adrenaline while in group B, amalgamated mixture of 2% lignocaine and 0.5% bupivacaine was used. The onset time, duration of anesthetic effect, supplementary injections, pain (during local anesthetic deposition, intra and postoperatively), and postoperative analgesia were the study parameters. Chi-square and unpaired t tests were used to compare means.

RESULTS

The onset time in both the groups was comparable and showed statistically significant difference between the duration of anesthetic effect with notable requirement of supplemental anesthetic injections in group A (54%) (p < 0.05). Pain scores also revealed a statistically significant intergroup difference (p < 0.05). Requirement of postoperative analgesics was delayed in group B.

CONCLUSIONS

The amalgamated mixture of lignocaine and bupivacaine had equivocally rational onset and provided a more profound and in-depth anesthesia especially in complicated and protracted minor oral surgical procedures. Though this mixture is widely used in other surgical fields, its efficacy still remains unexploited and undocumented in oral and maxillofacial surgical procedures.

Optimal Solubility of Diclofenac β-Cyclodextrin in Combination with Local Anaesthetics for Mesotherapy Applications

Because of low injection volume, the recently marketed injectable solution of diclofenac in complex with β-cyclodextrin (Akis®, IBSA Farmaceutici Italia) is an ideal candidate for mesotherapy applications. In this study, we investigated the solubility of Akis, 25 and 50 mg/kg, in combination with various local anaesthetics (lidocaine, mepivacaine, bupivacaine, levobupivacaine, and ropivacaine) at different concentrations in aqueous vehicles (normal saline, sterile water, or bicarbonate). Final injection mixtures were classified as limpid, turbid, or milky at visual analysis under standardized conditions. We found that (i) the use of sterile water for injections or normal saline as vehicles to dilute Akis in combination with whatever local anaesthetic normally results in milky solutions and therefore is not recommended; (ii) using bicarbonate, optimal solubility was obtained combining Akis with lidocaine, both 1 and 2%, or mepivacaine, both 1 and 2%, whereas solutions were turbid in combination with bupivacaine, levobupivacaine, or ropivacaine. Thus, we recommend that Akis is used in combination with lidocaine or mepivacaine in a bicarbonate vehicle.