Pain-less injection: principles and pearls.

There has been an exponential growth in the number of dermatologic procedures performed over the past two decades. This surge in procedural volumes is accompanied by increasing utilization of local anesthetics. A proper technique in administering local anesthesia is necessary to minimize pain and promote comfort, as it is often regarded as the most painful part of cutaneous procedures. Pain is a psychophysiological phenomenon that involves attention, cognitive appraisal, and emotion. Sensory feedback and anxiety are two important aspects of pain perception. This article aims to introduce a novel way that minimizes pain and discomfort associated with local anesthetics. It is the authors' experience that painless injection is achievable by keeping syringes/needles out of sight, proceeding with injection without pre-procedure warning, and engaging patients in a conversation or simple tasks.

The Calvarial Injection Assay.

This chapter describes the calvarial injection method, whereby the effect of a substance on bone is tested by subcutaneous injection over the calvarium of a mouse. This assay allows testing of the effect of substances on both bone resorption and bone formation in a relatively simple in vivo model. The analysis is carried out by histological means, usually in glycolmethacrylate-embedded tissue, allowing for histochemical analysis and for a variety of different histological staining methods which are also described in detail.

Reduced pain when injecting lidocaine. / Mindre smerte ved lokalbedøvelse.

Pain on injection of lidocaine is often considered a necessary evil, but it can be reduced by simple means.

Evaluation of mesotherapy as a transdermal drug delivery tool.

BACKGROUND: There has been no research about the exact mechanism of transdermal drug delivery during mesotherapy. OBJECTIVE: We aimed to evaluate whether the commercial mesogun can be an appropriate technique for a transdermal drug delivery. MATERIALS AND METHODS: We injected blue ink into the polyurethane foam or pig skin with three types of mesotherapy using a commercial mesogun, or local made intradermal injector, or a manual injection of syringe. To assess the internal pressure of the cylinder and drug delivery time, we designed the evaluation setup using a needle tip pressure transducer. RESULT: All types of injectors induced adequate penetration of blue ink into the polyurethane foam without backflow. In the pig skin, blue ink leaked out rapidly with the backward movement of the needle in the commercial mesogun in contrast to the local made injector or the manual injection of syringe. When the time for backward movement of the syringe approaches 1000 ms, the cylinder pressure of the syringe is saturated at around 25 mmHg which can be translated into the dermal pressure of the pig skin. CONCLUSION: There should be sufficient time between the insertion and withdrawal of the needle of injector for the adequate transdermal drug delivery and it must be considered for mesotherapy.

Minimizing the pain of local anesthesia injection.

BACKGROUND: Local anesthetic injection is often cited in literature as the most painful part of minor procedures. It is also very possible for all doctors to get better at giving local anesthesia with less pain for patients. The purpose of this article is to illustrate and simplify how to inject local anesthesia in an almost pain-free manner. METHODS: The information was obtained from reviewing the best evidence, from an extensive review of the literature (from 1950 to August of 2012) and from the experience gained by asking over 500 patients to score injectors by reporting the number of times they felt pain during the injection process. RESULTS: The results are summarized in a logical stepwise pattern mimicking the procedural steps of an anesthetic injection-beginning with solution selection and preparation, followed by equipment choices, patient education, topical site preparation, and finally procedural techniques. CONCLUSIONS: There are now excellent techniques for minimizing anesthetic injection pain, with supporting evidence varying from anecdotal to systematic reviews. Medical students and residents can easily learn techniques that reliably limit the pain of local anesthetic injection to the minimal discomfort of only the first fine needlestick. By combining many of these conclusions and techniques offered in the literature, tumescent local anesthetic can be administered to a substantial area such as a hand and forearm for tendon transfers or a face for rhytidectomy, with the patient feeling just the initial poke.

Increasing local blood flow by warming the application site: beneficial effects on postprandial glycemic excursions.

The absorption profile of rapid-acting insulin analogs delivered subcutaneously is slow compared with physiological insulin. Shorter time to peak and shorter duration of insulin action are important steps toward reducing high postprandial blood glucose concentrations in diabetes therapy and are critical for the development of a closed-loop insulin delivery system. Many attempts have been made to develop more rapid-acting insulins. Since the 1950s, different approaches, such as jet injectors and sprinkler needles, which try to increase the absorption areas of injected insulin, have been developed; however, none of them are commonly used in diabetes therapy. Massage and heat increase tissue blood perfusion and, thereby, the absorption of subcutaneously applied insulin. The main focus of this article is a novel device that allows local application of heat to human skin. The device can be connected to a regular insulin pump. This device could demonstrate a significant effect on insulin absorption and postprandial glucose excursions in multiple clinical trials.

An analysis of the mixing efficiency of neutral protamine Hagedorn cartridges.

In this issue of Journal of Diabetes Science and Technology, Kaiser and colleagues conducted an investigation to identify variations in the delivered dose of several different isophane insulin (neutral protamine Hagedorn, NPH) brands that use glass and metal bodies ("bullets") to facilitate mixing. Using a strategy where multiple pens from each of five different NPH insulin products (Insuman Basal, sanofi-aventis, three metal bullets; Humulin N, Lilly, one glass bullet; Berlinsulin H Basal, Berlin-Chemie, one glass bullet; Insulin B. Braun Basal, two glass bullets; and Protaphane Penfill, NovoNordisk, one glass bullet) were compared at multiple sampling points and over a range of mixing procedures (3, 6, 10, and 20 times), the authors identified deviations in the delivered dose of insulin at initial use and with repeated dosing. At the initial dose, adhering with manufacturer recommendations to conduct the mixing procedure 10-20 times was found to demonstrate minimal deviation and there was no pronounced difference among the products. Decreasing the number of mixing procedures from 10-20 to 3-6 times, a more profound deviation was noted, with the Insuman Basal product demonstrating less variability in comparison to all other products evaluated. A repeated dose study (1, 2, 6, and 10) with only six mixing procedures revealed that the insulin concentration of each dose increased for all products except Insuman Basal. Clinically, numerous factors may contribute to variability observed with subcutaneous administration of isophane insulin. While data presented by Kaiser and colleagues demonstrated that the issue of proper mixing is not trivial, the modest differences observed between and within products both at the initial dose and with repeated dosing may indicate that the clinical relevance of these findings is most applicable to those requiring large doses or, alternatively, those who have otherwise unexplained hypoglycemic episodes.

Compatibility and stability of dexamethasone sodium phosphate and ketamine hydrochloride subcutaneous infusions in polypropylene syringes.

The stability of ketamine hydrochloride injection and dexamethasone sodium phosphate injection, when mixed and stored in polypropylene syringes, was studied. Formulations containing ketamine hydrochloride (50 mg or 600 mg) and dexamethasone sodium phosphate (1 mg) in 0.9% sodium chloride injection (to 14 ml) were prepared and stored at 4 degrees C, 23 degrees C, and 37 degrees C, under normal fluorescent light conditions, for 192 hours. The concentrations of the drugs were determined at 0, 2, 4, 8, 24, 48, 96, and 192 hours using a validated high-pressure liquid chromatography method. The pH, color, and visible particles of each solution were also assessed at each time point. All formulations tested maintained more than 98% of the initial concentrations of both drugs, and no degradation products were detected. The solutions remained clear and colorless and the pH varied within 0.05 units throughout 192 hours. The results indicate that, at the concentrations studied, combinations of ketamine hydrochloride and dexamethasone sodium phosphate in 0.9% sodium chloride injection were physically and chemically stable for at least 192 hours (8 days) when stored in polypropylene syringes.

Are needle-free injections a useful alternative for growth hormone therapy in children? Safety and pharmacokinetics of growth hormone delivered by a new needle-free injection device compared to a fine gauge needle.

The clinical safety, use and pharmacokinetics of a new needle-free device for delivery of growth hormone (GH) were compared with those of conventional needle injection devices. In an open-label, randomized, 4-period crossover study, 18 healthy adults received single subcutaneous injections of Genotropin administered by the Genotropin ZipTip needle-free device and by conventional injection. Bioequivalence was established between the devices. In a separate open-label, randomized, multicenter, 2-period crossover study, pediatric patients underwent 2-weeks Genotropin treatment administered by the Genotropin ZipTip and by a fine-gauge needle device (>95% used the Genotropin Pen). In total, 128/133 patients who were treated completed the study. Genotropin ZipTip was well tolerated and >50% of patients found no difference between the devices for all parameters assessed. After study completion, >20% patients preferred to continue using Genotropin ZipTip. Although statistical analyses demonstrated superiority of the Genotropin Pen versus Genotropin ZipTip for bleeding, pain, soreness, and bruising, Genotropin ZipTip was considered to provide a safe and bioequivalent alternative to needle injection.

Slow infusion tumescent anesthesia.

BACKGROUND: Dermatologic surgery is usually possible under local anesthesia, even when large amounts of highly diluted anesthetic solution are required (tumescent anesthesia). Although special pumps now render such large injections effortless, it is usually still necessary to hold and guide the injection cannula. OBJECTIVE: We have found it possible to overcome this handicap by injecting anesthetic solutions slowly with a common infusomat, as in paravenous infusion, into the subcutaneous layer. METHODS: The method consists of slow, automated tumescent anesthesia by means of infusion. The speed of injection varies between 50 and 1500 mL per hour depending on the location, the size of the operation, and the needle size. Volumes usually range from 2 to 500 mL but may rise as high as 1000 mL if necessary (maximum, 12 mg/kg). We use 30- to 20-gauge needles with a length of 1.5-10 cm and butterfly infusion cannulas. We customarily use an anesthetic solution of prilocaine (Xylonest); the dilution liquid is original Ringer's solution with epinephrine (1:1,000,000) in 500-mL bottles. The concentration of the solution varies between 0.4% and 0.1%. After setting up the system during pulsoxymetry, the physician can usually leave the room. This is calming, especially for children and very anxious patients. We used the slow infusion tumescent anesthesia (SITA) in our department to treat 502 patients ranging in age from 3 to 92 years (mean age, 51 years). We performed all kinds of tumor operations (n = 213), dermabrasions (n = 5), scar revisions (n = 21), stripping of the long and short saphenous veins (n = 82), sentinel node dissection (n = 27), complete lymph node dissection of the axilla (n = 12) and groin (n = 17), and 125 minor operations as well. RESULTS: There were no severe complications. One hundred ten (91%) of 121 patients who had previously experienced general or regional anesthesia for the same kind of surgery and all who had previously had conventional syringe injection preferred SITA. CONCLUSIONS: SITA is an economical, safe, and comfortable technique for nearly all skin operations, even for children and very sensitive patients. Choosing the most suitable concentration, needle, needle position, flow ad volume requires some experience.

Tumescent anesthesia with a lidocaine dose of 55 mg/kg is safe for liposuction.

BACKGROUND: The safe upper limit of lidocaine dosage in tumescent anesthesia for liposuction has been reported to be 35 mg/kg. OBJECTIVE: This study was undertaken to: 1) evaluate the safety of tumescent anesthesia in liposuction when lidocaine doses greater than 35 mg/kg are required, 2) determine the time interval when the peak plasma lidocaine level occurs following administration of tumescent anesthesia, and 3) assess if the safety of large volume tumescent anesthesia is due to significant lidocaine removed by liposuction. METHODS: Sixty patients who underwent liposuction with a mean lidocaine dose of 57 mg/kg were prospectively evaluated for development of any signs or symptoms of lidocaine toxicity by multiple interviews over a 24-hour period. In addition, another 10 patients who received a mean lidocaine dose of 55 mg/kg had serial plasma lidocaine level measurements over a 24-hour period following liposuction. The lidocaine level of the aspirate was also measured to assess any significant lidocaine removed by liposuction. RESULTS: No evidence of lidocaine toxicity was found based on subjective evaluation of 60 patients as well as determined by plasma sampling of 10 patients. The peak plasma lidocaine concentration occurred at approximately 4 or 8 hours after infusion of tumescent anesthesia. The 24-hour plasma lidocaine level suggests that residual lidocaine is present in the subcutaneous tissue allowing for postoperative analgesia beyond this time. A negligible amount of lidocaine was removed by liposuction as determined by the lidocaine level of the aspirate. CONCLUSION: This study suggests that tumescent anesthesia with a total lidocaine dose of up to 55 mg/kg is safe for use in liposuction.

Performance of disposable needle syringe systems for local anesthesia.

The performance of different disposable needle syringe systems was determined by measuring needle-puncture pain, needle-bending forces, and the fluid dynamics of the systems. Thirty-gauge needles cause less needle-puncture pain than any other needle. The force required to bend the 30-gauge needle irreversibly was lower than that for the other needles. Studies of the fluid dynamics of different needle syringe assemblies demonstrated that the flow rate can be limited by using large-size syringes (30 mL) and needles with the smallest internal diameter. On the basis of the results of this study, 30-gauge needles attached to 10-mL syringes are recommended for infiltration anesthesia, and 25-gauge needles with 10-mL syringes are advocated for regional nerve blocks. In infiltration anesthesia, the local anesthetic agent should be injected slowly into the subdermal tissue over a 10-second period. When performing regional nerve blocks, it is also advisable to inject the local anesthetic agent over a 10-second time interval.