[Alkalinization of local anesthetics: theoretically justified but clinically useless]

Tumescent technique for split-thickness skin graft donor sites: A systematic review of randomized controlled trials

BACKGROUND

Split-thickness skin grafting (STSG) is widely used for reconstructive wound management. This review aimed to use level I evidence to determine if tumescent techniques were safe and effective compared to other interventions for STSG donor sites. It was hypothesized that tumescent techniques were safe and effective for STSG donor sites.

METHODS

Five databases (MEDLINE via PubMed, Embase, Cochrane Library, Web of Science, and Scopus) were searched to identify studies concerning the use of tumescent solutions for STSG. Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and Cochrane's guidelines were strictly followed.

RESULTS

Nine randomized controlled trials met the criteria. Included studies were published from 2001 to 2021, with results from 40 of 121 possible queried outcomes and complications. Outcomes included patient demographics, formulations of tumescent solutions, tumescent technique, hemodynamics, pain, perfusion, graft take, healing time, and postoperative complications. The tumescent technique reduced estimated blood loss (standard mean differences [SMD]: -2.68, 95%CI: -3.41 to -1.94; participants = 72; studies = 2; I2 = 96%; p < 0.001), and postoperative analgesic use within 24 hours (SMD: -1.75, 95%CI: -2.09 to -1.41; participants = 202; studies = 2; I2 = 96%; p < 0.001), without increasing graft loss/take (SMD: 0.29, 95%CI: -0.02 to 0.61; participants = 158; studies = 3; I2 = 41%; p = 0.07) and infection (risk ratios [RR]: 0.52, 95%CI: 0.08 to 3.54; participants = 87; studies = 3; I2 = 0%; p = 0.58) complications compared to other interventions.

CONCLUSIONS

Level I evidence demonstrated tumescent techniques were safe and effective for STSG donor sites. Tumescent techniques reduced blood loss and postoperative analgesic use within 24 hours without increasing graft loss/take and infection complications compared to other interventions. Inconsistencies between studies limit conclusions and emphasize the need for standardized protocols regarding tumescent solution formulations, techniques, and reported outcomes.

The effect of warming ropivacaine on ultrasound-guided subgluteal sciatic nerve block: a randomized controlled trial

BACKGROUND

There is a long latent period for the sciatic nerve block before a satisfactory block is attained. Changes in the temperature of local anesthetics may influence the characters of the peripheral nerve block. This study was designed to evaluate the effect of warming ropivacaine on the ultrasound-guided subgluteal sciatic nerve block.

METHODS

Fifty-four patients for distal lower limbs surgery were randomly allocated into warming group (group W, n = 27) or room tempeture group (group R, n = 27) with the ultrasound-guided subgluteal sciatic nerve block. The group W received 30 ml of ropivacaine 0.5% at 30℃ and the group R received 30 ml of ropivacaine 0.5% at 23℃. The sensory and motor blockade were assessed every 2 min for 30 min after injection. The primary outcome was the onset time of limb sensory blockade.

RESULTS

The onset time of sensory blockade was shorter in group W than in group R (16 (16,18) min vs 22 (20,23) min, p < 0.001), and the onset time of motor blockade was also shorter in group W than in group R (22 (20,24) min vs 26 (24,28) min, p < 0.001). The onset time of sensory blockade for each nerve was shorter in group W than in group R (p < 0.001). No obvious differences for the duration of sensory and motor blockade and the patient satisfaction were discovered between both groups. No complications associated with nerve block were observed 2 days after surgery.

CONCLUSIONS

Warming ropivacaine 0.5% to 30℃ accelerates the onset time of sensory and motor blockade in the ultrasound-guided subgluteal sciatic nerve block and it has no influence on the duration of sensory and motor blockade.

TRIAL REGISTRATION

The trial was registered on October 3, 2022 in the Chinese Clinical Trial Registry ( https://www.chictr.org.cn/bin/project/edit?pid=181104 ), registration number ChiCTR2200064350 (03/10/2022).

Interaction between Dexamethasone, Ropivacaine, and Contrast Media Used in Interventional Pain Treatment: Considerations in Safety

Background and Objectives: Although epidural steroid injections are used as an effective treatment, this technique is associated with rare but serious ischemic complications, especially when particulate steroids are used. However, recent studies have reported that even if non-particulate steroids are used, particulates are formed by the interaction with some local anesthetics (LA), causing ischemic complications. This observational study evaluated commonly used combinations of non-particulate steroids and LA with contrast media via microscopic analysis and analyzed the chemical properties of each mixture to identify the correlation of particulate formation. Materials and Methods: Commonly used clinical non-particulate and particulate steroids, contrast media, and LA agent combinations were evaluated macroscopically and microscopically. The pH values were also measured at both room temperature (26 °C) and body temperature (36 °C). Where particulates were observed, the particulate size was measured. Results: Macroscopically, the mixture of non-particulate steroid and ropivacaine had a slightly cloudy appearance at all concentrations, but there was no visible particulate. However, when observed under a microscope, the pH-dependent particulate formation was observed at all concentration combinations tested. (0.1% ropivacaine: from 19 μm to 70 μm, and 0.2% ropivacaine: from 37 μm to 108 μm at room temperature (26 °C)). When contrast media was mixed or the temperature was raised to body temperature (36 °C), the number and size of the particulates decreased or dissolved. Conclusions: The combination of ropivacaine and dexamethasone, a non-particulate steroid, mainly used in epidural injections, forms particulates. However, when mixed with contrast media, particulates are dissolved because of changes in pH and factors affecting particulate formation. In fluoroscopy-guided injections, the use of contrast media could resolve particulate formation.

Effect of warming bupivacaine 0.5% on ultrasound-guided axillary plexus block. Randomized prospective double-blind study

OBJECTIVE

To evaluate the effect of warming bupivacaine 0.5% on ultrasound-guided axillary brachial plexus block.

STUDY DESIGN

Prospective, randomized, double-blind.

PATIENTS AND METHODS

Eighty patients undergoing elective or emergency surgery beyond the distal third of the upper limb were divided into two groups of 40 patients: the warm group received 15mL bupivacaine 0.5% heated to 37°C; the cold group received 15mL 0.5% bupivacaine stored for at least 24hours in the lower compartment of a refrigerator at 13-15°C. Onset and duration of sensory and motor blocks were evaluated every 5minutes for 40minutes. Postoperative pain was evaluated at 1, 3, 6, 12 and 24hours. Effective analgesia time was recorded as the interval between anesthetic injection and the first analgesia requirement (VAS>30mm).

RESULTS

Time to onset of sensory and motor block was significantly shorter in the warm group, and mean duration of sensory and motor block and of postoperative analgesia significantly longer.

CONCLUSION

Warming bupivacaine 0.5% to 37°C accelerated onset of sensory and motor block and extended action duration.

Crystallization of Local Anesthetics When Mixed With Corticosteroid Solutions

Objective

To evaluate at which pH level various local anesthetics precipitate, and to confirm which combination of corticosteroid and local anesthetic crystallizes.

Methods

Each of ropivacaine-HCl, bupivacaine-HCl, and lidocaine-HCl was mixed with 4 different concentrations of NaOH solutions. Also, each of the three local anesthetics was mixed with the same volume of 3 corticosteroid solutions (triamcinolone acetonide, dexamethasone sodium phosphate, and betamethasone sodium phosphate). Precipitation of the local anesthetics (or not) was observed, by the naked eye and by microscope. The pH of each solution and the size of the precipitated crystal were measured.

Results

Alkalinized with NaOH to a certain value of pH, local anesthetics precipitated (ropivacaine pH 6.9, bupivacaine pH 7.7, and lidocaine pH 12.9). Precipitation was observed as a cloudy appearance by the naked eye and as the aggregation of small particles (<10 µm) by microscope. The amount of particles and aggregation increased with increased pH. Mixed with betamethasone sodium phosphate, ropivacaine was precipitated in the form of numerous large crystals (>300 µm, pH 7.5). Ropivacaine with dexamethasone sodium phosphate also precipitated, but it was only observable by microscope (a few crystals of 10–100 µm, pH 7.0). Bupivacaine with betamethasone sodium phosphate formed precipitates of non-aggregated smaller particles (<10 µm, pH 7.7). Lidocaine mixed with corticosteroids did not precipitate.

Conclusion

Ropivacaine and bupivacaine can precipitate by alkalinization at a physiological pH, and therefore also produce crystals at a physiological pH when they are mixed with betamethasone sodium phosphate. Thus, the potential risk should be noted for their use in interventions, such as epidural steroid injections.

Combating inadequate anesthesia in periapical infections, with sodium bicarbonate: a clinical double blind study

INTRODUCTION

Local anesthetics are generally much less effective when administered in inflamed tissues.

PURPOSE

This study was conducted to validate the addition of sodium bicarbonate in local anesthetics to increase its effectiveness as local infiltrations in teeth associated with periapical infections.

METHODS

Two hundred subjects requiring extraction of maxillary teeth with periapical infections were enrolled. These subjects were divided in two groups of 100 subjects each. One group received local infiltration with 2 % lignocaine and 1:80,000 adrenaline, and the other group received local infiltration with sodium bicarbonate as an adjunct to the above mentioned local anesthetic solution. All extractions were performed using a consistent intra-alveolar technique by a single operator. Both the patient and the operator were blinded to the contents of local anesthetic solution. Data related to the onset of action of local anesthesia, pain experienced by the patient while undergoing extraction on two scales-"the visual analog scale and the verbal response scale", and any requirement of repeated injections during the procedure was recorded.

RESULTS

Clinical and statistical data confirmed that the addition of sodium bicarbonate in local anesthetics did increase the efficacy of local anesthesia in inflamed tissues.

CONCLUSION

It has been observed in this study that the action of sodium bicarbonate in local anesthetics increases the pH levels of these solutions, thus possibly making them more effective in an acidic environment.

Partial evacuation of the fracture haematoma does not potentiate the analgesic effect of infiltrated local anaesthetic in the manipulation of distal radius fractures

Wrist haematoma blocks increase the volume of the fracture-soft tissue envelope and the resulting compartment pressures. We hypothesised that evacuating the haematoma before infiltrating with local anaesthetic would reduce the risk of undue swelling and produce a more effective block as measured by changes in a visual analogue score for pain. A total of 100 patients (100 fractures) were recruited; 77 had the haematoma partially evacuated (Group 1) and 23 did not (Group 2). The volumes of infiltrated anaesthetic, timing of manipulation, rates of re-manipulation and splitting of cast were not different between the two groups. The mean visual analogue score before manipulation in the two groups were 7.8 and 7.5, respectively, which declined to 3.2 and 2.5 at 5 min and to 2.8 and 2.4 at 10 min. The differences in change in visual analogue score were not significant at 5 and 10 min ( p = 0.42, p = 0.55). This suggests that evacuation of the haematoma does not influence the analgesic effect of the infiltrated agent.

Wound infiltration with magnesium sulphate and ropivacaine mixture reduces postoperative tramadol requirements after radical prostatectomy

PURPOSE

This prospective, randomized, double-dummy study was undertaken to compare the effects of magnesium sulphate (MgSO(4)) administered by the intravenous vs. the infiltration route on postoperative pain and analgesic requirements.

METHODS

Forty ASA I or II men scheduled for radical retropubic prostatectomy under general anaesthesia were randomized into two groups (n=20 each). Two medication sets A and B were prepared at the pharmacy. Each set contained a minibag of 50 ml solution for IV infusion and a syringe of 45 ml for wound infiltration. Group MgSO(4).IV patients received set A with 50 mg/kg MgSO(4) in the minibag and 190 mg of ropivacaine in the syringe. Group MgSO(4)/L received set B with isotonic saline in the minibag and 190 mg of ropivacaine +750 mg of MgSO(4) in the syringe. The IV infusion was performed over 30 min at induction of anaesthesia and the surgical wound infiltration was performed during closure. Pain was assessed every 4 h, using a 100-point visual analogue scale (VAS). Postoperative analgesia was standardized using IV paracetamol (1 g/6 h) and tramadol was administered via a patient-controlled analgesia system. The follow-up period was 24 h.

RESULTS

The total cumulative tramadol consumption was 221 +/- 64.1 mg in group MgSO4.IV and 134 +/- 74.9 mg in group MgSO(4).L (P<0.01). VAS pain scores were equivalent in the two groups throughout the study. No side-effects, due to systemic or local MgSO(4) administration, were observed.

CONCLUSION

Co-administration of MgSO(4) with ropivacaine for postoperative infiltration analgesia after radical retropubic prostatectomy produces a significant reduction in tramadol requirements.

Local infiltration of epinephrine-containing lidocaine with bicarbonate reduces superficial bleeding and pain during labor epidural catheter insertion: a randomized trial

BACKGROUND

Superficial bleeding after labor epidural catheter placement is a common phenomenon. In addition to delaying securing the epidural catheter, it may loosen the adhesive catheter dressing. The primary aim of this study was to determine whether skin infiltration with epinephrine-containing rather than plain lidocaine reduces superficial bleeding after catheter placement. Secondary objectives were to determine whether adding epinephrine and/or sodium bicarbonate affected infiltration pain.

METHODS

After institutional review board approval and informed consent, 80 healthy women receiving epidural analgesia during labor were randomly assigned in a double-blind manner to four local anesthetic mixtures (n=20 in each group): group L: lidocaine 1.5%, group LB: lidocaine 1.5% with 8.4% sodium bicarbonate, group LE: lidocaine 1.5% with epinephrine 1:200000, and group LEB: lidocaine 1.5% with epinephrine 1:200000 and 8.4% sodium bicarbonate. Clinical endpoints included the amount of superficial bleeding at the catheter site, pain during local anesthetic infiltration and epidural catheter movement during labor.

RESULTS

Demographic data were similar among the groups. The addition of epinephrine to lidocaine significantly reduced superficial bleeding. Solutions containing epinephrine were well tolerated and caused no cardiovascular disturbances. The addition of epinephrine did not increase pain, while bicarbonate reduced it [verbal score (scale 0-10) 3.6+/-2.2 vs. 2.6+/-1.8; P=0.04]. There were no differences in epidural catheter movement among the groups; no catheters became displaced during labor.

CONCLUSION

Local infiltration of epinephrine-containing lidocaine before epidural catheter insertion reduces superficial bleeding and the addition of bicarbonate decreases pain during skin infiltration.

Perioperative interscalene blockade: an overview of its history and current clinical use

Use of single-dose and continuous interscalene brachial plexus block (ISB) are gaining widespread popularity. When compared with general anesthesia, ISB has been reported to provide superior postoperative analgesia with fewer side effects, and it is associated with greater patient satisfaction. Anatomical landmarks are readily identifiable, which contributes to the ease of performing this block. In the future, we anticipate increased use of continuous interscalene catheters or injection of biodegradable local anesthetic impregnated microspheres to provide prolonged perioperative outpatient analgesia.

Chemical stability of bupivacaine, lidocaine and epinephrine in pH-adjusted solutions

Epinephrine and sodium bicarbonate may be added to local anaesthetic solutions in order to reduce the onset time and enhance the quality of epidural anaesthesia for Caesarean section. Such mixtures are sometimes prepared several hours in advance for subsequent use in emergency Caesarean section through a pre-existing epidural catheter. To evaluate this practice, we studied the chemical stability in solution over 24 h of nine epidural mixtures consisting of different combinations of bupivacaine, lidocaine, epinephrine and sodium bicarbonate. In mixtures alkalinised with sodium bicarbonate, epinephrine concentrations decreased significantly over 24 h (p<0.0001), whereas those in nonalkalinised mixtures did not change with time. Bupivacaine and lidocaine concentrations in all mixtures did not decrease over time regardless of alkalinisation. We do not recommend adding epinephrine to alkalinised epidural solutions that are to be stored for a prolonged period before clinical use.

The effect of needle gauge and lidocaine pH on pain during intradermal injection

Local anesthetics can produce pain during skin infiltration. We designed a randomized, prospective trial to determine whether needle gauge and/or solution pH affect pain during the intradermal infiltration of lidocaine. After approval by our institution's human studies review board, 40 healthy adult volunteers gave their consent to participate in this study. All of the volunteers randomly received four intradermal injections. Each volunteer was blinded as to the content of the intradermal injections and to which needle size was used for each injection. Each volunteer randomly received a 0.25-mL intradermal injection of the following four solutions: 1) lidocaine 2% administered through a 25-gauge needle (lido-25); 2) lidocaine 2% mixed with sodium bicarbonate (4 mL of 2% lidocaine plus 1 mL of sodium bicarbonate, pH 7.26) administered through a 25-gauge needle (lido-bicarb-25); 3) lidocaine 2% administered through a 30-gauge needle (lido-30); and 4) lidocaine 2% mixed with sodium bicarbonate (4 mL of 2% lidocaine plus 1 mL of sodium bicarbonate) administered through a 30-gauge needle (lido-bicarb-30). In each patient, the injection site was in the same region for each of the four injections. The skin wheal was tested for appropriate anesthesia using a 19-gauge needle on the skin wheal. A visual analog pain score was recorded after each intradermal injection. The pain scores were significantly higher in the lido-25 (3.2 +/- 0.2) group than in the lido-30 (2.5 +/- 0.3), lido-bicarb-25 (1.9 +/- 0.2), and lido-bicarb-30 (1.3 +/- 0.2) groups. The lido-bicarb-30 injection was also rated as less painful than the lido-30 injection. We found no differences between the lidobicarb-25 and the lido-bicarb-30 injections. Complete analgesia for the 19-gauge needle pain stimulus was achieved in all patients for each injection. We conclude that, overall, the pain intensity of an intradermal injection of 2% lidocaine is low. The addition of sodium bicarbonate to 2% lidocaine decreases the pain associated with an intradermal skin wheal, and although the use of a 30-gauge needle decreases the pain of injection, the addition of sodium bicarbonate seems to have a greater overall effect than needle size.

IMPLICATIONS

Forty volunteers randomly received four intradermal injections consisting of 2% lidocaine with or without sodium bicarbonate via a 25- or 30-gauge needle. The addition of bicarbonate had a greater overall effect than needle size in decreasing the pain associated with the intradermal injection of lidocaine.