Topical Anesthetics for Dermal Instrumentation: A Systematic Review of Randomized, Controlled Trials

The Effect of Granisetron on Sensory Detection and Pain Thresholds in Facial Skin of Healthy Young Males

Background: The specific serotonin type 3 (5-HT₃)-receptor antagonist granisetron effectively reduces clinical as well as experimental muscle pain and hyperalgesia and with a duration that exceeds that of lidocaine. Hence, it may be an alternative to lidocaine as a local anesthetic. There are also some indications that granisetron in addition to 5-HT₃ receptors blocks sodium channels. Thus, the local anesthetic effect by granisetron may resemble that of lidocaine, but this has not been tested. The aim of this study was therefore to compare the effect granisetron has on facial skin sensitivity to the effect of lidocaine and isotonic saline.

Methods: This was a randomized, controlled, and double-blind study, in which 1 ml of either granisetron (test-substance), lidocaine (positive control), or isotonic saline (negative control) was injected into the skin over the masseter muscle at three different occasions in 18 healthy males (27.2 ± 5.8 years old). Skin detection thresholds and pain thresholds for thermal stimuli as well as mechanical detection thresholds and sensitivity to a painful mechanical (pinprick) stimulus were assessed before (baseline) and 5, 20, 40, and 60 min after injection. The quality and area of subjective sensory change over the cheek were assessed 20 min after injection.

Results: All substances increased the mechanical detection threshold (granisetron: p = 0.011; lidocaine: p = 0.016; saline: p = 0.031). Both granisetron and lidocaine, but not isotonic saline, increased the heat detection thresholds (p < 0.001 and p < 0.02, respectively), but not the cold detection thresholds. Granisetron and lidocaine also reduced pinprick pain (p = 0.001 for each comparison). There were no significant differences between granisetron and lidocaine for any of these variables. There was no effect on thermal pain thresholds for any substance.

Conclusion: The similar analgesic patterns on mechanical sensory and pain thresholds as well as thermal sensory thresholds over the facial skin by subcutaneous injection of granisetron and lidocaine shown in this study and the absence of paresthesia, in combination with the reduced pain intensity and pressure pain sensitivity shown in previous studies, indicate that granisetron might be a novel candidate as a local anesthetic.

Topical anesthetics for pediatric laser treatment

Topical anesthetic agent causes transient insensibility to pain in a limited area of skin, and provides effective anesthesia in a short onset time, short duration, with seldom local or systemic side effects on intact skin and is simple to use. Topical formulations may offer significant benefits for prevention of procedural pain. Currently, they are considered to be the most effective anesthesia for laser treatments. Unfortunately, there is no standard anesthetic technique for this procedure. Lasers are being widely used in numerous dermatological and esthetics treatments in childhood. The advancement of new knowledge in laser technology have contributed to the development of new lasers that are commonly used in a pediatric population, such as Pulsed Dye, Carbon-dioxide and Nd:YAG laser. The most commonly used topical anesthetics in young patients for minimally or moderately painful laser cutaneous procedures are Lidocaine, Prilocaine, Tetracaine gel and combinations thereof.

Local anesthesia and anxiolytic techniques for oculoplastic surgery

This study discusses local anesthetic agents, administration techniques, ancillary considerations, and safety precautions for oculoplastic surgery including eyelid, lacrimal, orbital, and temporal artery biopsy procedures. Methods for reducing patient apprehension and discomfort including systemic premedication, topical pre-anesthetic, visual, auditory and tactile distraction techniques, regional blocks, small gauge needles, warmed lidocaine, and buffered lidocaine are discussed.

Liposomal-based lidocaine formulation for the improvement of infiltrative buccal anaesthesia

This study describes the encapsulation of the local anaesthetic lidocaine (LDC) in large unilamellar liposomes (LUV) prepared in a scalable procedure, with hydrogenated soybean phosphatidylcholine, cholesterol and mannitol. Structural properties of the liposomes were assessed by dynamic light scattering, nanoparticle tracking analysis and transmission electron microscopy. A modified, two-compartment Franz-cell system was used to evaluate the release kinetics of LDC from the liposomes. The in vivo anaesthetic effect of liposomal LDC 2% (LUV_LDC) was compared to LDC 2% solution without (LDC_PLAIN) or with the vasoconstrictor epinephrine (1:100 000) (LDC_VASO), in rat infraorbital nerve blockade model. The structural characterization revealed liposomes with spherical shape, average size distribution of 250 nm and low polydispersity even after LDC incorporation. Zeta potential laid around -30 mV and the number of suspended liposomal particles was in the range of 10¹² vesicles/mL. Also the addition of cryoprotectant (mannitol) did not provoke structural changes in liposomes properties. In vitro release profile of LDC from LUV fits well with a biexponential model, in which the LDC encapsulated (EE% = 24%) was responsible for an increase of 67% in the release time in relation to LDC_PLAIN (p < 0.05). Also, the liposomal formulation prolonged the sensorial nervous blockade duration (∼70 min), in comparison with LDC_PLAIN (45 min), but less than LDC_VASO (130 min). In this context, this study showed that the liposomal formulations prepared by scalable procedure were suitable to promote longer and safer buccal anaesthesia, avoiding side effects of the use of vasoconstrictors.

Distraction Technique for pain reduction in Peripheral Venous Catheterization: randomized, controlled trial

Background and aim of the work: Procedural pain during Peripheral Venous Catheterization (PVC) is a significant issue for patients. Reducing procedure-induced pain improves the quality of care and reduces patient discomfort. We aimed to compare a non-pharmacological technique (distraction) to anaesthetic cream (EMLA) for the reduction of procedural pain during PVC, in patients undergoing Computerized Tomography (CT) or Nuclear Magnetic Resonance (NMR) with contrast. Methods: This is a Prospective, Randomized Controlled Trial. The study was carried out during the month of October 2015. A total of 72 patients undergoing PVC were randomly assigned to the experimental group (distraction technique, n=36) or control group (EMLA, n=36). After PVC, pain was evaluated by means of the numeric pain-rating scale (NRS). Pain perception was compared by means of Mann-Whitney Test. Results: The average pain in the distraction group was 0.69 (SD±1.26), with a median value of 0. The average pain in the EMLA group was 1.86 (SD±1.73), with a median value of 2. The study showed a significant improvement from the distraction technique (U=347, p<.001, r=.42) with respect to the local anaesthetic in reducing pain perception. Conclusions/Implication for practice: Distraction is more effective than local anaesthetic in reducing of pain-perception during PVC insertion. This study is one of few comparing the distraction technique to an anaesthetic. It confirms that the practitioner-patient relationship is an important point in nursing assistance, allowing the establishment of trust with the patient and increasing compliance during the treatment process.

Fear of Injections and Needle Phobia Among Children and Adolescents: An Overview of Psychological, Behavioral, and Contextual Factors

The purpose of this clinical update is to provide an overview of the fear of needles and needle phobia in children and adolescents including characteristics and diagnosis, prevalence and epidemiology, etiological factors, and treatment options. Needle-related fear and needle phobia present as significant needle-related distress and avoidance behavior. The etiology is biopsychosocial. These challenging conditions are more common in children and adolescents than in adults. The nurse-patient relationship enables the provision of suitable preparation before injection procedures. Nurses can use exposure-based interventions and incorporate coping strategies and teaching of parents and children. Nurses play a pivotal role in noticing the need for further treatment. Procedural needle-related distress is a complex phenomenon representing a continuum ranging from needle fear to more severe needle phobia. For patients with needle fear management and training methods used by nurses can possibly prevent a progression of the condition into needle phobia. In cases of needle phobia, a correct diagnosis made by a psychiatrist is necessary and enables referral to a psychotherapist with experience in treating children and adolescents with needle phobia.

Comparison of the Analgesic Effect of an Ice Cube versus 4% Lidocaine Cream in Intradermal Antibiotic Skin Testing

Objective

This study was performed to compare the analgesic effect of an ice cube with that of 4% lidocaine cream (L.M.X.4®) for intradermal skin testing.

Methods

In this prospective randomised study, healthy adult volunteers were divided into ice cube and lidocaine analgesic pretreatment groups. Randomisation was performed using a randomisation table in blocks of four. Intradermal skin testing was performed after applying ice in the ice cube group and 5 mg of lidocaine cream in the lidocaine group. After the intradermal skin test, the pain intensity was investigated using the visual analog scale (VAS) on questionnaires. We calculated that a minimum of 24 subjects were required for statistical power of 80% at a significance level of 0.05 (two-sided). The groups' VAS scores were compared using the Mann-Whitney U-test.

Results

The study population consisted of 35 volunteers: 17 in the ice cube group and 18 in the lidocaine group. There were no differences in demographic characteristics between the two groups. The median VAS score was 20 (interquartile range: 0-35) in the ice cube group and 70 (interquartile range: 50-80) in the lidocaine group (p<0.001).

Conclusions

The results suggested the utility of an ice cube as analgesic pretreatment for intradermal skin testing in the emergency department.

Laceration Management

BACKGROUND

Traumatic lacerations to the skin represent a fairly common reason for seeking emergency department care. Although the incidence of lacerations has decreased over the past decades, traumatic cutaneous lacerations remain a common reason for patients to seek emergency department care.

OBJECTIVE

Innovations in laceration management have the potential to improve patient experience with this common presentation.

DISCUSSION

Studies have confirmed that delays in wound closure rarely confer increased rates of infection, although comorbidities such as diabetes, chronic renal failure, obesity, human immunodeficiency virus, smoking, and cancer should be considered. Antibiotics should be reserved for high-risk wounds, such as those with comorbidities, gross contamination, involvement of deeper structures, stellate wounds, and selected bite wounds. Topical anesthetics, which are painless to apply, have a role in select populations. In most studies, absorbable sutures perform similarly to nonabsorbable sutures and do not require revisit for removal. Novel atraumatic closure devices and expanded use of tissue adhesives for wounds under tension further erode the primacy of regular sutures in wound closure. Maintaining a moist wound environment with occlusive dressings is more important than previously thought. Most topical wound agents are of limited benefit.

CONCLUSIONS

Recent innovations in wound closure are allowing emergency physicians to shift toward painless, atraumatic, and rapid closure of lacerations.

Intra-pocket anaesthesia and pain during probing, scaling and root planing: a systematic review and meta-analysis

AIM

A systematic review/meta-analysis was performed to evaluate pain during probing, scaling and root planing using intra-pocket anaesthesia versus placebo in adult patients.

METHODS

A search was performed in PubMed, Scopus, Web of Science, Latin American and Caribbean Health Sciences Literature database, Brazilian Library in Dentistry, Cochrane Library and Grey literature. IADR abstracts, unpublished trials registries, dissertations and theses were also searched for randomized clinical trials comparing the clinical effectiveness of intra-pocket anaesthesia and placebo. Risk/intensity of pain was the primary outcome. The risk of bias tool from the Cochrane Collaboration was used for quality assessment. Meta-analysis was performed on studies considered at low risk of bias.

RESULTS

A total of 1740 articles were identified. Eleven remained in the qualitative synthesis, and nine studies were considered at "low" risk of bias for meta-analysis. Standardized Hedge's g mean difference for pain intensity using visual analogue scale and Heft-Parker pain scales was -0.576 (95% confidence interval [CI] -0.94 to -0.22; p = 0.002) and for verbal rating scale pain scale it was -1.814 (95% CI -3.38 to -0.245; p = 0.023). The odds ratio for the risk of pain was 0.025 (95% CI 0.003 to 0.25; p = 0.002) and the odds ratio for the need for rescue anaesthesia it was 0.358 (95% CI 0.174 to 0.736; p = 0.005).

CONCLUSIONS

The anaesthetic gel decreases the risk and intensity of pain during probing/SRP.

Does Topical Anesthetic Reduce Pain During Intraosseous Pin Removal in Children? A Randomized Controlled Trial

BACKGROUND

The purpose of this study was to determine the effectiveness of topical liposomal lidocaine in reducing the pain perceived by children undergoing percutaneous intraosseous pin (PP) removal in the outpatient orthopaedic clinic.

METHODS

A triple-blinded, randomized, placebo-controlled clinical trial comparing topical liposomal lidocaine to a placebo was conducted at the Stollery Children's Hospital between September 2008 and February 2011. Subjects undergoing the removal of PP in the orthopaedic outpatient clinic between ages 3 and 16 years were recruited. A computer-generated variable-block randomization scheme was used to determine each subject's group assignment. Pain was recorded just before randomization and immediately after the procedure using the Oucher Scale (for subjects) and a 10-cm Visual Analog Scale (for parents and an observing orthopaedic technician). In a subset of individuals, follow-up telephone calls were made 24 hours postprocedure to inquire about any adverse event from the use of the topical liposomal lidocaine. Data were analyzed using the Student t test.

RESULTS

Of a total of 296 recruited subjects, complete data were available on 281 subjects (140 intervention and 141 control). There were no significant differences between the 2 groups with regards to baseline characteristics, including preprocedure pain scores. Although postprocedure pain scores demonstrated an increase in pain in both groups (2.3 points in the treatment group and 2.0 points in the placebo group), no statistically significant difference was seen in postprocedure pain scores between groups (P=0.81). No adverse events were observed or reported.

CONCLUSIONS

Topically applied liposomal lidocaine was not effective in reducing pain during this procedure, compared with a placebo. However, this study demonstrates that PP removal is a painful procedure in children. Given the large volume of patients who undergo this procedure and the long-term consequences of experiencing painful procedures in childhood, it is important to find safe and fast-acting methods to decrease procedural pain associated with PP removal.

An Evidence-Based Approach to Minimizing Acute Procedural Pain in the Emergency Department and Beyond

BACKGROUND

Painful procedures are common in the ED setting and beyond. Although these procedures are often essential to patient management, they can also be distressing for children, parents, and health providers. As such, it is imperative that effective pain and anxiety-minimizing strategies be used consistently in all settings where painful procedures take place for children.

OBJECTIVES

This review article aims to provide a summary of several strategies, which are supported by definitive and systematically reviewed evidence, that can be implemented alone or in combination to reduce procedural pain and anxiety for children in the ED and beyond.

RESULTS

For neonates, breastfeeding, nonnutritive sucking, swaddling, and sucrose administration have all been shown to decrease pain during painful interventions. For neonates, venipuncture is much less painful than heel lance for blood draws. For infants, there is some support for sucrose use. For infants and older children, there is strong evidence for distraction techniques. In addition, the use of fast-acting topical anesthetic creams as an alternative or adjunct to infiltrating anesthetic before laceration repair or vascular access/venipuncture is recommended. Further, buffering of lidocaine can decrease pain during injection. Lastly, if a laceration is amenable to the use of tissue adhesive, this should be preferentially used.

CONCLUSIONS

In summary, there currently remains a knowledge-to-practice gap in the treatment of children's procedure-related pain. This article has identified multiple age-specific methods to improve the treatment of procedural pain. These simple interventions can improve the care provided to ill and injured children.

Efficacy and Safety of a Lidocaine Gel in Patients from 6 Months up to 8 Years with Acute Painful Sites in the Oral Cavity: A Randomized, Placebo-Controlled, Double-Blind, Comparative Study

Lidocaine is a well-accepted topical anaesthetic, also used in minors to treat painful conditions on mucosal membranes. This randomized, double-blind, placebo-controlled study (registered prospectively as EudraCT number 2011-005336-25) was designed to generate efficacy and safety data for a lidocaine gel (2%) in younger children with painful conditions in the oral cavity. One hundred sixty-one children were included in two subgroups: 4–8 years, average age 6.4 years, treated with verum or placebo and 6 months–<4 years, average age 1.8 years, treated only with verum. Pain reduction was measured from the time prior to administration to 10 or 30 minutes after. In addition, adverse events and local tolerability were evaluated. In group I, pain was reduced significantly after treatment with verum compared to placebo at both time points. In group II, the individual pain rating shift showed statistically significant lower pain after treatment. Only seven out of 161 patients reported an adverse event but none were classified as being related to the study medication. The local tolerability was assessed as very good in over 97% of cases. For painful sites in the oral cavity, a 2% lidocaine gel is a meaningful tool for short-term treatment in the paediatric population.

Comparative Efficacy and Patient Preference of Topical Anaesthetics in Dermatological Laser Treatments and Skin Microneedling

Background:

Topical anaesthetics are effective for patients undergoing superficial dermatological and laser procedures. Our objective was to compare the efficacy and patient preference of three commonly used topical anaesthetics: (2.5% lidocaine/2.5% prilocaine cream (EMLA^®), 4% tetracaine gel (Ametop™) and 4% liposomal lidocaine gel (LMX4^®)) in patients undergoing laser procedures and skin microneedling.

Settings and Design:

This was a prospective, double-blind study of patients undergoing laser and skin microneedling procedures at a laser unit in a tertiary referral dermatology centre.

Materials and Methods:

All 29 patients had three topical anaesthetics applied under occlusion for 1 hour prior to the procedure, at different treatment sites within the same anatomical zone. A self-assessment numerical pain rating scale was given to each patient to rate the pain during the procedure and each patient was asked to specify their preferred choice of topical anaesthetic at the end of the procedure.

Statistical Analysis:

Parametric data (mean pain scores and frequency of topical anaesthetic agent of choice) were compared using the paired samples t-test. A P-value of ≤0.05 was considered as statistically significant.

Results and Conclusions:

Patients reported a mean (±SD; 95% confidence interval) pain score of 5 (±2.58; 3.66-6.46) with Ametop™, 4.38 (±2.53; 2.64-4.89) with EMLA^® and 3.91 (±1.95; 2.65-4.76) with LMX4^®. There was no statistically significant difference in pain scores between the different topical anaesthetics. The majority of patients preferred LMX4^® as their choice of topical anaesthetic for dermatological laser and skin microneedling procedures.

Comparing lignocaine-adrenaline-tetracaine gel with lignocaine infiltration for anesthesia during repair of lacerations: A randomized trial

BACKGROUND

This study aimed to compare the topical anesthetic lignocaine, adrenaline, and tetracaine (LAT) (4% lignocaine, 1:2 000 adrenaline, 1% tetracaine) with the conventional lignocaine infiltration(LI) for repair of minor lacerations, for the comfort of anesthetic administration, efficacy, adverse effects and cost.

METHODS

This was a prospective randomized clinical trial. Forty Asian patients who required toilet and suture for minor lacerations in the emergency department of the Singapore General Hospital over a 4-month period. The patients were assigned randomly to 2 arms of treatment. The first was the LAT gel group who had LAT gel applied to the laceration prior to suturing. The second was the control group in whom the anesthetic administered was lignocaine infiltration (LI) via a syringe. The pain of the process of administering anesthetic and efficacy of anesthesia were scored using the visual pain scale included within. The efficacy of LAT vs. lignocaine infiltration as an anesthetic prior to the toilet and suture of minor lacerations and complications of therapy.

RESULTS

Twenty patients were randomized to LAT gel and 16 to LI on an intention to treat analysis. The mean pain score by patients in the LAT gel group was 2.5 (0.52 SE), and 2.5 (0.58 SE) in the LI group. The pain score for pain during application of the anesthetic was 1.5 (0.40) in the LAT gel group, and 3.5 (0.46) in the LI group. There was no difference in complications between the LAT and LI groups.

CONCLUSION

LAT gel prior to the toilet and suture of minor lacerations is proven to be as efficacious as LI in terms of patient comfort and effectiveness of anesthesia. The complications are also comparable to those treated with LI.

Association between Multiple IV attempts and Perceived Pain levels in the Emergency Department

Purpose

Intravenous (IV) access is the most commonly performed procedure in the emergency department (ED). Patients with difficult venous access require multiple needlesticks (MNS) for successful IV cannulation and may experience increased pain with many attempts.

Objective

To determine the association between number of IV attempts and overall pain experienced by the patient from IV placement.

Methods

Cross-sectional observational study on consecutive patients undergoing IV placement with a 20-gauge IV in the upper extremity in an urban academic hospital. Exclusion criteria included refusal to participate or fully complete all survey questions. The total number of IV attempts and patient pain scores marked on a standardized visual analog scale was recorded. Mean pain scores of two groups, single needlestick (SNS) and MNS, were compared using Student's t-test.

Results

A total of 760 patients were approached, of whom 31 were excluded, leaving 729 patients in the analysis; 556 with SNS (76%) and 173 with MNS (24%). The mean pain score (95% CI) was 51 mm (46–55 mm) for the MNS group and 25 mm (23–28 mm) for the SNS group, p<0.001. Compared to patients who underwent one IV attempt, patients with two and three attempts had an average 19 mm and 33 mm increase in pain scores, respectively, with the highest average pain associated with five attempts. A total of 58% of MNS patients rated IV placement as the most painful experience while in the ED.

Conclusions

Patients experience increased pain in association with multiple IV attempts.

Local anesthetics for skin grafting and local flaps

In plastic surgery, there are many procedures that can be performed using local instead of general anesthesia. Not only can this help mitigate health care costs, but precious operating-room resources can also be directed to areas of greater need. Common procedures that can be performed under local anesthetics include skin grafts and local flaps. However, as not all patients are suitable for local anesthesia, careful patient selection is necessary to maintain the standard of care. This article describes the detailed surgical approach to using local anesthetics for skin grafts and local flaps.

Liposomal lidocaine gel for topical use at the oral mucosa: characterization, in vitro assays and in vivo anesthetic efficacy in humans

OBJECTIVE

To characterize liposomal-lidocaine formulations for topical use on oral mucosa and to compare their in vitro permeation and in vivo anesthetic efficacy with commercially available lidocaine formulations.

MATERIALS AND METHODS

Large unilamellar liposomes (400 nm) containing lidocaine were prepared using phosphatidylcholine, cholesterol, and α-tocoferol (4:3:0.07, w:w:w) and were characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and in vitro release. In vitro permeation across pig palatal mucosa and in vivo topical anesthetic efficacy on the palatal mucosa in healthy volunteers (double-blinded cross-over, placebo controlled study) were performed. The following formulations were tested: liposome-encapsulated 5% lidocaine (Liposome-Lido5); liposome-encapsulated 2.5% lidocaine (Liposome-Lido2.5); 5% lidocaine ointment (Xylocaina®), and eutectic mixture of lidocaine and prilocaine 2.5% (EMLA®).

RESULTS

The Liposome-Lido5 and EMLA showed the best in vitro permeation parameters (flux and permeability coefficient) in comparison with Xylocaina and placebo groups, as well as the best in vivo topical anesthetic efficacy.

CONCLUSION

We successfully developed and characterized a liposome encapsulated 5% lidocaine gel. It could be considered an option to other topical anesthetic agents for oral mucosa.

Efficacy and safety of a lidocaine/tetracaine medicated patch or peel for dermatologic procedures: a meta-analysis

Background

To justify the use of the lidocaine/tetracaine medicated patch or peel as a preventive treatment for reducing pain and discomfort in adults and children. We reviewed randomized controlled trials (RCTs) to evaluate the efficacy and safety of the lidocaine/tetracaine medicated patch or peel compared with placebo.

Methods

Ten RCTs (574 patients) were included in this systemic review. Relevant studies were identified through searches of MEDLINE, SCOPUS and the Cochrane database library. The outcome was the adequacy of cutaneous anesthesia reflected in the patient's assessment of pain intensity during minor dermatologic procedures and adverse effects after application of the lidocaine/tetracaine medicated patch or peel versus placebo.

Results

The efficacy of the lidocaine/tetracaine patch or peel was consistently very significantly beneficial 30 or 60 minutes after the application compared to placebo (Relative risk, RR: 2.5; Number needed to treat, NNT: 2.2). We did not identify any difference in the effectiveness of adequate analgesia between the lidocaine/tetracaine patch and peel (the number needed to treat or to harm, NNT 2.4 vs. 2.0). No serious side effects or adverse events were observed with the lidocaine/tetracaine medicated patch or peel and placebo. Minor skin reactions were transient and resolved without treatment (Odd ratio, OR: 1.4 and 95% confidence interval, CI: 0.9-2.1; NNT: 14.9).

Conclusions

The lidocaine/tetracaine medicated patch or peel is a well accepted, effective and safe method for minor dermatologic procedures based on pooled data of trials in terms of adequacy of cutaneous anesthesia and adverse effects.

New delivery systems for local anaesthetics-part 2

Part 2 of this paper deals with the techniques for drug delivery of topical and injectable local anaesthetics. The various routes of local anaesthetic delivery (epidural, peripheral, wound catheters, intra-nasal, intra-vesical, intra-articular, intra-osseous) are explored. To enhance transdermal local anaesthetic permeation, additional methods to the use of an eutectic mixture of local anaesthetics and the use of controlled heat can be used. These methods include iontophoresis, electroporation, sonophoresis, and magnetophoresis. The potential clinical uses of topical local anaesthetics are elucidated. Iontophoresis, the active transportation of a drug into the skin using a constant low-voltage direct current is discussed. It is desirable to prolong local anaesthetic blockade by extending its sensory component only. The optimal release and safety of the encapsulated local anaesthetic agents still need to be determined. The use of different delivery systems should provide the clinician with both an extended range and choice in the degree of prolongation of action of each agent.

Contribution of a heating element to topical anesthesia patch efficacy prior to vascular access: results from two randomized, double-blind studies

CONTEXT

Pain associated with superficial procedures, including intravenous (IV) access procedures, should be prevented when possible, especially in children.

OBJECTIVES

To evaluate a topical local anesthetic patch containing lidocaine 70 mg/tetracaine 70 mg with a heating element designed to warm the skin and facilitate rapid delivery of local anesthetics into the skin. The pilot study was designed to provide data to inform the design of the definitive study to evaluate the impact of controlled heat on the efficacy of the lidocaine/tetracaine patch (patch) when applied before IV cannulation.

METHODS

Subjects in the pilot study were randomized to eight groups that varied by heated vs. unheated patch, 20 vs. 30 minute application, and 16 vs. 18 G catheter. Subjects in the definitive study were randomized in a double-blind manner to receive either the heated or unheated patch, 20 minutes before vascular access, using a 16 G catheter in the antecubital space of the arm. In both studies, the primary efficacy measure was subject-reported pain intensity using a visual analog scale.

RESULTS

Pilot study: Subjects who received the heated patch (n=43) vs. the unheated patch (n=37) had lower mean pain intensity scores (14.7 vs. 23.5mm, P=0.04). Pain intensity scores did not differ significantly by application time, but the difference between the 16 and 18 G catheter groups approached statistical significance (22.8 vs. 14.9 mm, P=0.05). Definitive study: Mean pain intensity scores for the heated patch group (n=124) vs. the unheated patch group (n=126) were 14.2 and 20.5mm, respectively (P=0.006).

CONCLUSION

Heated patches provided significantly better pain relief compared with unheated patches. All the subjects tolerated the patches well, with few adverse effects.

Thyroid fine needle aspiration biopsy: is topical local anaesthesia beneficial?

OBJECTIVE

Thyroid fine needle aspiration biopsy (TFNAB) is the gold standard in the differential diagnosis of the thyroid nodules. In general, no analgesia is needed before this procedure. However, it is usually believed that the patients may be more comfortable if the procedure is performed under local anaesthetics. In this study, we examined the impact of the use of dermal anaesthetic on the patient's level of discomfort during palpation-guided TFNAB.

METHODS

Fifty female patients with nodular goitre were enrolled in this study. Patients were randomised into two groups: a placebo cream was applied to group 1 patients (25 females; mean age 47.45 +/- 11.61 years), and local anaesthesia (EMLA 5% cream) was applied to group 2 patients (25 females; mean age 50.89 +/- 12.01 years) approximately 1 h before TFNAB. All patients were asked to mark the pain they felt during the TFNAB on Visual Analogue Scale.

RESULTS

The pain scores during TFNAB were 27.73 +/- 20.01 mm and 24.79 +/- 21.98 mm in the placebo group and in the EMLA group respectively. There was no significant difference between the groups (p = 0.496).

CONCLUSIONS

Topical anaesthesia before palpation-guided TFNAB provides no benefit.

Local anesthetics: uses and toxicities

Surgeons are asked to do more and larger procedures as outpatient procedures as the economics of medicine evolve. Indeed, we all carry out procedures on an outpatient basis that only a short time ago we would consider only on an inpatient basis. Further, procedures that had previously been performed under a general anesthetic are now being performed under local anesthesia. A good working knowledge of local anesthetics (LAs) will better enable the surgeon to meet those demands and to do so in a way that will enhance the patient's safety, experience, and comfort. Although the focus of this issue of Clinics is minor surgery, any meaningful discussion of LAs has to go a little further than a 3-mL syringe and a small amount of lidocaine.

The analgesic efficacy of lidocaine/prilocaine (EMLA) cream during fine-needle aspiration biopsy of thyroid nodules

OBJECTIVE

Pain is one of the few drawbacks of fine-needle aspiration biopsy (FNAB) in patients with nodular thyroid disease (NTD). Lidocaine/prilocaine cream, an eutectic mixture of local anaesthetics (EMLA), is a frequently used topical anaesthetic. Despite its well-documented efficacy for the relief of pain associated with other cutaneous procedures that involve needle insertion, the analgesic role of EMLA has not been previously reported in patients with NTD who are undergoing FNAB. The aim of this study was to determine the analgesic efficacy of EMLA for FNAB-associated pain in patients with NTD.

DESIGN

Double-blind, placebo-controlled clinical trial.

PATIENTS

The study was conducted at a thyroid outpatient clinic. We studied 99 patients with NTD.

MEASUREMENTS

Patients with NTD were allocated to receive either 2.5 g of EMLA (n = 50) or placebo (n = 49) 60 min before ultrasonographically guided FNAB. A series of four biopsies of each nodule was performed. Patients rated pain associated with the procedure according to a 100-mm visual analogue scale (VAS), an 11-point numeric rating scale (NRS), and 4-category verbal rating scale (VRS).

RESULTS

When the EMLA group was compared with the placebo group, there were no significant differences with respect to age, sex, thyroid volume, nodule size or nodule site. Significant differences were noted in the pain ratings of the two groups according to all three pain scales. When the effectiveness of EMLA was compared with that of placebo, the mean VAS score was 25.0 +/- 22.3 mm vs. 40.0 +/- 30.5 mm (P = 0.006) and the mean NRS score was 2.9 +/- 2.3 points vs. 4.0 +/- 2.6 points (P = 0.02). The absolute numbers according to VRS score in each group was also significantly different (P = 0.01). Although our sample size was small, the data suggest that FNAB-associated pain was sex-related and that women were significantly more sensitive than were men (P = 0.003 for VAS score and P = 0.001 for NRS score). No adverse effects from the use of EMLA were reported.

CONCLUSIONS

To our knowledge, this is the first study demonstrating that a topical anaesthetic, EMLA, provides an effective and noninvasive analgesia during the FNAB of NTD.

Skin surgery in children: local anaesthesia and sedation techniques

In the past, procedural pain control in young children was undertreated as it was incorrectly alleged that their neuronal pain pathways were undeveloped. However, it is now recognised that even neonates are able to experience pain. Moreover, intensely painful physical experiences in childhood can have persisting physiological and psychological consequences. Therefore, the management of acute pain is essential. In this paper, the authors provide an in-depth discussion regarding the anaesthetic options for paediatric patients undergoing dermatological surgery.

Hemoglobin adducts of the human bladder carcinogen o-toluidine after treatment with the local anesthetic prilocaine

Prilocaine, a widely used local anesthetic, is metabolized to o-toluidine which is classified as human carcinogen. We aimed to assess the impact of prilocaine-treatment on hemoglobin adducts from o-toluidine. Blood samples were obtained before and 24h after receiving prilocaine local anesthesia (Xylonest, 100mg) from 20 head and neck surgery patients and 6 healthy volunteers. Hemoglobin adducts of o-toluidine and 4-aminobiphenyl were determined by gas chromatography/mass spectrometry. Hemoglobin adducts of o-toluidine were significantly increased 24h after 100mg prilocaine-treatment by 21.6+/-12.8ng/g hemoglobin (mean+/-S.D., N=26; P<0.0001). This corresponds to a 6-360-fold increase of o-toluidine adduct levels in 25 patients from 0.54+/-0.95ng/g before treatment to 22.0+/-13.2ng/g 24h after surgery (mean+/-S.D.). Because of an extremely high background level the increase was only 1.6-fold in one patient (40.9ng/g before and 64.4ng/g 24h after prilocaine injection). Current smoking had no influence on background values and on the increase of o-toluidine adducts. No treatment-related differences were seen in mean hemoglobin adduct levels of 4-aminobiphenyl which were significantly higher in smokers, 0.149+/-0.096ng/g (mean+/-S.D., N=8) as compared to nonsmokers 0.036+/-0.035ng/g (mean+/-S.D., N=16; P<0.01). In conclusion, prilocaine anesthesia leads to a massive increase of hemoglobin adducts of the carcinogenic arylamine o-toluidine. This implies a carcinogenic risk which should be taken into account in preventive hazard minimization.

Nanotechnology: intelligent design to treat complex disease

The purpose of this expert review is to discuss the impact of nanotechnology in the treatment of the major health threats including cancer, infections, metabolic diseases, autoimmune diseases, and inflammations. Indeed, during the past 30 years, the explosive growth of nanotechnology has burst into challenging innovations in pharmacology, the main input being the ability to perform temporal and spatial site-specific delivery. This has led to some marketed compounds through the last decade. Although the introduction of nanotechnology obviously permitted to step over numerous milestones toward the development of the "magic bullet" proposed a century ago by the immunologist Paul Ehrlich, there are, however, unresolved delivery problems to be still addressed. These scientific and technological locks are discussed along this review together with an analysis of the current situation concerning the industrial development.