Epinephrine auto-injectors: is needle length adequate for delivery of epinephrine intramuscularly?

Optimal dose of adrenaline auto-injector for children and young people at risk of anaphylaxis: A phase IV randomized controlled crossover study

BACKGROUND

Guidelines recommend intramuscular injection of 500 μg adrenaline (epinephrine) for anaphylaxis in teenagers and adults; however, most autoinjectors deliver a maximum 300 μg dose. We evaluated plasma adrenaline levels and cardiovascular parameters (including cardiac output) following self-injection with 300 μg or 500 μg adrenaline in teenagers at risk of anaphylaxis.

METHODS

Subjects were recruited to a randomized, single-blind two period crossover trial. Participants received all 3 injections (Emerade® 500 μg, Emerade® 300 μg, Epipen® 0.3 mg) on 2 separate visits (allocated in a randomized block design), at least 28 days apart. Intramuscular injection was confirmed by ultrasound, and heart rate/stroke volume assessed using continuous monitoring. The trial was registered at Clinicaltrials.gov (NCT03366298).

RESULTS

Twelve participants (58% male, median 15.4 years) participated; all completed the study. 500 μg injection resulted in a higher and more prolonged peak concentration (p = 0.01) and greater Area-Under-Curve for plasma adrenaline (p < 0.05) compared to 300 μg, with no difference in adverse events. Adrenaline caused a significant increase in heart rate irrespective of dose and device. Unexpectedly, 300 μg adrenaline resulted in a significant increase in stroke volume when delivered with Emerade®, but a negative inotropic effect with Epipen® (p < 0.05).

CONCLUSIONS

These data support a 500 μg dose of adrenaline to treat anaphylaxis in individuals >40 kg in the community. The contrasting effects on stroke volume between Epipen® and Emerade®, despite similar peak plasma adrenaline levels, are unexpected. There is an urgent need to better understand differences in pharmacodynamics following adrenaline administration by autoinjector. In the meantime, we recommend adrenaline injection by needle/syringe in the healthcare setting in individuals with anaphylaxis refractory to initial treatment.

Ideal body position for epinephrine autoinjector administration

Background: Epinephrine is the first-line therapy for patients with anaphylaxis, and intramuscular (IM) delivery is shown to be superior to subcutaneous (SC) delivery. There currently is no consensus on the ideal body position for epinephrine autoinjector (EAI) administration. Objective: We designed this study to investigate whether SC tissue depth (SCTD) is affected by body position (e.g., standing, sitting, supine), which can potentially impact delivery of EAI into the IM space. Methods: Volunteer adults (ages ≥ 18 years) from a military medical treatment facility in the United States were recruited to participate in this study. SCTD of the vastus lateralis was measured via ultrasound at standing, sitting, and supine body positions. Subjects' age, sex, and body mass index (BMI) were collected. Statistical analysis was performed to compare average SCTD between body positions, sex, and BMI. Results: An analysis of variance of 51 participants (33 men and 18 women) did not reveal statistically significant difference in SCTD among standing, sitting, and supine body positions. It did show a significantly greater SCTD in women than in men (2.72 ± 1.36 cm versus 1.10 ± 0.38 cm; p < 0.001). There was no significant association observed between BMI and SCTD in this study. Conclusion: Body position did not seem to significantly change the distance between skin and thigh muscle in adults. This would suggest that there might not be an ideal body position for EAI administration. Therefore, in case of anaphylaxis, prompt administration of epinephrine is recommended at any position.

Pharmacokinetic and pharmacodynamic evidence of adrenaline administered via auto-injector for anaphylactic reactions: A review of literature

Anaphylaxis is a severe allergic reaction that can lead to death if not treated quickly. Adrenaline (epinephrine) is the first-line treatment for anaphylaxis and its prompt administration is vital to reduce mortality. Following a number of high-profile cases, serious concerns have been raised, both about the optimal dose of intramuscular adrenaline via an auto-injector and the correct needle length to ensure maximal penetration every time. To date, the public data are sparse on the pharmacokinetics-pharmacodynamics of adrenaline administered via an auto-injector. The limited available literature showed a huge variation in the plasma concentrations of adrenaline administered through an auto-injector, as well as variations in the auto-injector needle length. Hence, delivering an effective dose during an anaphylaxis remains a challenge for both patients and healthcare professionals. Collaborative work between pharmacokinetics-pharmacodynamics experts, clinical triallists and licence holders is imperative to address this gap in evidence so that we can improve outcomes of anaphylaxis. In addition, we advise inclusion of expertise of human factors in usability studies given the necessity of carer or self-administration in the uniquely stressful nature of anaphylaxis.

Non-Auto-Injector Epinephrine Administration by Basic Life Support Providers: A Literature Review and Consensus Process

Anaphylaxis is a life-threatening condition with a known effective prehospital intervention: parenteral epinephrine. The National Association of EMS Physicians (NAEMSP) advocates for emergency medical services (EMS) providers to be allowed to carry and administer epinephrine. Some states constrain epinephrine administration by basic life support (BLS) providers to administration using epinephrine auto-injectors (EAIs), but the cost and supply of EAIs limits the ability of some EMS agencies to provide epinephrine for anaphylaxis. This literature review and consensus report describes the extant literature and the practical and policy issues related to non-EAI administration of epinephrine for anaphylaxis, and serves as a supplementary resource document for the revised NAEMSP position statement on the use of epinephrine in the out-of-hospital treatment of anaphylaxis, complementing (but not replacing) prior resource documents. The report concludes that there is some evidence that intramuscular injection of epinephrine drawn up from a vial or ampule by appropriately trained EMS providers-without limitation to specific certification levels-is safe, facilitates timely treatment of patients, and reduces costs.

Point-of-care ultrasonography in the allergy and immunology clinic

OBJECTIVE

To summarize evidence supporting the use of point-of-care ultrasonography as a clinical tool for allergists and immunologists.

DATA SOURCES

Cochrane Library, Medline, EMBASE, and Scopus databases were searched for articles published before December 18, 2018.

STUDY SELECTIONS

We included any retrospective or prospective study that evaluated ultrasonography in allergy and immunology and epinephrine autoinjector (EAI) needle length.

RESULTS

The standard EAI needle length may be inadequate for intramuscular delivery of epinephrine, particularly for women, at risk of anaphylaxis. In patients who weigh less than 15 kg, the lengths of commercially available EAIs may be too long, risking inadvertent intraosseous injection and resultant complications. Ultrasonography can be routinely used in the allergy clinic to guide needle length and angle for subcutaneous allergen immunotherapy injections to minimize systemic adverse effects.

CONCLUSION

Point-of-care ultrasonography can be a useful tool to enhance patient care and safety in an allergy clinic. Ideally, all patients prescribed EAIs should have ultrasonographic measurement of the skin to muscle distance and skin to bone distance to assist in identifying patients at risk of subcutaneous or intraosseous injection in anaphylaxis and those at risk of intramuscular injection during subcutaneous allergen immunotherapy injections.

A narrative review of the success of intramuscular gluteal injections and its impact in psychiatry

There are 12 billion injections given worldwide every year. For many injections, the intramuscular route is favoured over the subcutaneous route due to the increased vascularity of muscle tissue and the corresponding increase in the bioavailability of drugs when administered intramuscularly. This paper is a review of the variables that affect the success of intramuscular injections and the implications that these success rates have in psychiatry and general medicine. Studies have shown that the success rates of intended intramuscular injections vary between 32 and 52%, with the rest potentially resulting in inadvertent subcutaneous drug deposition. These rates are found to be even lower for certain at-risk populations, such as obese patients and those on antipsychotic medications. The variables associated with an increased risk of injection failure include female sex, obesity, site of injection, and subcutaneous fat depth. New guidelines and methods are needed in order to address this challenge and ensure that patients receive optimum care. Looking forward, the best way to improve the delivery of intramuscular injections worldwide is to develop uniform algorithms or innovative medical devices to confirm or guarantee successful delivery at the bedside.

Epinephrine auto-injector needle lengths: Can both subcutaneous and periosteal/intraosseous injection be avoided?

BACKGROUND

Epinephrine should be administered intramuscularly in the anterolateral aspect of the thigh. The length of the epinephrine auto-injector (EAI) needle should ensure intramuscular injection.

OBJECTIVE

To discuss suitable EAI needle lengths based on ultrasound measurements related to weight.

METHODS

The skin-to-muscle distance (STMD) and skin-to-bone distance (STBD) were measured by ultrasound in the mid-third of the anterolateral area of the right thigh when applying high pressure (8 lb; high-pressure EAI [HPEAI]) or low pressure (low-pressure EAI [LPEAI]) on the ultrasound probe. The study included 302 children and adolescents and 99 adults. The maximum and minimum STMD and the maximum and minimum STBD were estimated.

RESULTS

Using HPEAIs, the risk of periosteal or intraosseous penetration was 32% in children weighing less than 15 kg. The risk of subcutaneous injection was 12% in adolescents and 33% in adults. With LPEAIs, there was no risk of periosteal or intraosseous injection and the risk of subcutaneous injections in adolescents and adults was lower at 2% and 10%, respectively. A new EAI for injection in small children would have no risk of periosteal or intraosseous injection but would have 71% chance of subcutaneous deposit of epinephrine.

CONCLUSION

Common HPEAIs have a high risk of periosteal or intraosseous penetration in children and subcutaneous injections in overweight and obese adults. LPEAIs have some risk of subcutaneous injection in adults. HPEAIs with 0.1 mg of epinephrine and shorter needles have no risk of periosteal or intraosseous injection but have a high risk of subcutaneous deposit. For adult or overweight or obese patients, HPEAIs and LPEAIs should have longer needles. Future studies should focus on triggering pressures and variations in needle length.

Epinephrine auto-injector needle length: what is the ideal length?

PURPOSE OF REVIEW

The purpose of this manuscript is to review the literature on the clinical effects of the needle length of epinephrine (adrenaline) auto-injectors.

RECENT FINDINGS

Epinephrine has maximal pharmacodynamic effect within 10 min of intramuscular administration into the thigh. Prefilled epinephrine auto-injectors are designed for simplicity of use and safety. Auto-injectors are primarily used by patients in an unsupervised setting in cases of anaphylaxis. There are weight-appropriate doses of epinephrine available with auto-injectors that are prefilled, to prevent dosing errors, with 0.15, 0.30, and 0.50 mg amounts. In addition, needle lengths vary from 1.17 to 2.50 cm. The recommended needle lengths differ between adults and pediatric patients. In addition, the needle lengths differ between devices as well. There are concerns that the needle length may be too short in select obese patients. Yet, there are also concerns that the needle length may be too long in some patients. Factors that affect the depth of the injection, and therefore the pharmacokinetics of the drug, include not only the needle length but also the BMI, obesity, compression of soft tissue, and propulsion.

SUMMARY

Epinephrine auto-injectors have different needle lengths. Using the right device with appropriate needle length based on BMI, obesity, and employing the proper technique can improve the outcome in an anaphylactic event.

Epinephrine Auto-Injector Versus Drawn Up Epinephrine for Anaphylaxis Management: A Scoping Review

OBJECTIVE

Anaphylaxis is a life-threatening event. Most clinical symptoms of anaphylaxis can be reversed by prompt intramuscular administration of epinephrine using an auto-injector or epinephrine drawn up in a syringe and delays and errors may be fatal. The aim of this scoping review is to identify and compare errors associated with use of epinephrine drawn up in a syringe versus epinephrine auto-injectors in order to assist hospitals as they choose which approach minimizes risk of adverse events for their patients.

DATA SOURCES

PubMed, Embase, CINAHL, Web of Science, and the Cochrane Library were searched using terms agreed to a priori.

STUDY SELECTION

We reviewed human and simulation studies reporting errors associated with the use of epinephrine in anaphylaxis. There were multiple screening stages with evolving feedback.

DATA EXTRACTION

Each study was independently assessed by two reviewers for eligibility. Data were extracted using an instrument modeled from the Zaza et al instrument and grouped into themes.

DATA SYNTHESIS

Three main themes were noted: 1) ergonomics, 2) dosing errors, and 3) errors due to route of administration. Significant knowledge gaps in the operation of epinephrine auto-injectors among healthcare providers, patients, and caregivers were identified. For epinephrine in a syringe, there were more frequent reports of incorrect dosing and erroneous IV administration with associated adverse cardiac events. For the epinephrine auto-injector, unintentional administration to the digit was an error reported on multiple occasions.

CONCLUSIONS

This scoping review highlights knowledge gaps and a diverse set of errors regardless of the approach to epinephrine preparation during management of anaphylaxis. There are more potentially life-threatening errors reported for epinephrine drawn up in a syringe than with the auto-injectors. The impact of these knowledge gaps and potentially fatal errors on patient outcomes, cost, and quality of care is worthy of further investigation.

Inadequacy of current pediatric epinephrine autoinjector needle length for use in infants and toddlers

BACKGROUND

Epinephrine injection represents the standard of care for anaphylaxis treatment. It is most effective if delivered intramuscularly, whereas inadvertent intraosseous injection may be harmful. The needle length in current pediatric epinephrine autoinjectors (EAIs) is 12.7 mm; however, the ideal needle length for infants and toddlers weighing less than 15 kg is unknown.

OBJECTIVE

To determine the skin-to-bone distance (STBD) and skin-to-muscle distance (STMD) at baseline and after simulated EAI application in infants and toddlers (weighing 7.5-15 kg).

METHODS

Study participants recruited from 2 North American allergy clinics underwent baseline and compression (10-lb pressure) ultrasonography of the anterolateral thigh with a modified ultrasound transducer mimicking the footprint and maximum pressure application of an EAI device. Ultrasound images, with clinical data masked, were analyzed offline for STBD and STMD in short-axis approach.

RESULTS

Of 53 infants (mean age, 18.9 months; 54.7% male; 81.1% white; mean weight, 11.0 kg), 51 had adequate images for short-axis STBD measurements. In these infants, the mean (SD) baseline STBD was 22.4 (3.8 mm), and the mean (SD) STMD was 7.9 (1.7) mm. With 10-lb compression, the mean (SD) STBD was 13.3 (2.1) mm, and the mean (SD) STMD was 6.3 (1.2) mm. An EAI with a needle length of 12.7 mm applying 10-lb pressure could strike the bone in 43.1% of infants and toddlers in this cohort.

CONCLUSION

Our data suggest that the optimal EAI needle length for infants and toddlers weighing 7.5 to 15 kg should be shorter than the needle length in currently available pediatric EAIs to avoid accidental intraosseous injections.

Skin to Intramuscular Compartment Thigh Measurement by Ultrasound in Pediatric Population

INTRODUCTION

Pediatric obesity threatens the efficacy of medications given intramuscularly. In anaphylactic patients, epinephrine auto-injector needle lengths are potentially too short to reach the muscle compartment in patients with elevated body habitus. The objective of the study was to determine needle-length requirements for intramuscular injections in pediatric patients.

METHODS

We used ultrasound to measure the distance from skin to muscle compartment of the thigh in 200 pediatric patients of various weight and body mass index who presented to the emergency department.

RESULTS

Patients with higher body mass index had an increased distance to muscle and bone. If current recommendations were followed, 5% of patients within the EpiPen adult weight category and 11% of patients within the Centers for Disease Control and Prevention weight category would have potentially used a needle inadequate in length for intramuscular injections.

CONCLUSION

With the increase in childhood obesity, needle lengths may be too short to effectively deliver medications to the intramuscular compartment. Needle length should be evaluated to accommodate pediatric patients with increased skin to muscle distance.

Efficacy of a Novel Prefilled, Single-Use, Needle-Free Device (Zeneo®) in Achieving Intramuscular Agent Delivery: An Observational Study

BACKGROUND

It is recognized that, as a result of variation in tissue anatomy, current auto-injectors may have insufficient needle length to achieve successful intramuscular agent delivery in a number of patients. The Zeneo^® auto-injector is a novel prefilled, single-use, needle-free device currently in development for intradermal, subcutaneous, and intramuscular agent delivery across a variety of clinical indications. We aimed to evaluate delivery depth of the device calibrated at pressure appropriate for intramuscular (IM) administration.

METHODS

This was a prospective single-center study in healthy adult volunteers, in whom each received a single injection of saline into the anterolateral thigh. Using sequential MRI scans, we measured skin-to-muscle distance (STMD) agent delivery depth, and the success of IM agent penetration. Device dynamic pressure measurements were also recorded.

RESULTS

Results are reported for 37 subjects with evaluable MRI scans; 19 men, 18 women; mean age 38 years (range 20-58); mean BMI 27.0 kg/m² (range 21.2-30.8 kg/m²). Mean STMD values were 18.6 mm (range 13.4-23.6 mm) in women and 10.0 mm (range 5.0-21.7 mm) in men, with gender differences due primarily to greater subcutaneous thickness in women. A trend for greater STMD in subjects with BMI greater than 25 kg/m² was seen. Mean injectate penetration depths of 30.1 mm (range 20.2-45.6 mm) were observed with values similar in male and female subjects. Successful IM delivery was reported in 95% of subjects. When failure occurred, this was not due to inadequate injection depth. Device pressure (P _max) had the greatest influence on injectate muscle penetration.

CONCLUSION

Use of the Zeneo^® auto-injector achieves delivery depth that ensures intramuscular delivery in both men and women, regardless of BMI. Consistent with other reported data, STMD is greater in women.

FUNDING

Crossject.

Autoinjectors Preferred for Intramuscular Epinephrine in Anaphylaxis and Allergic Reactions

INTRODUCTION

Epinephrine is the treatment of choice for anaphylaxis. We surveyed emergency department (ED) healthcare providers regarding two methods of intramuscular (IM) epinephrine administration (autoinjector and manual injection) for the management of anaphylaxis and allergic reactions and identified provider perceptions and preferred method of medication delivery.

METHODS

This observational study adhered to survey reporting guidelines. It was performed through a Web-based survey completed by healthcare providers at an academic ED. The primary outcomes were assessment of provider perceptions and identification of the preferred IM epinephrine administration method by ED healthcare providers.

RESULTS

Of 217 ED healthcare providers invited to participate, 172 (79%) completed the survey. Overall, 82% of respondents preferred the autoinjector method of epinephrine administration. Providers rated the autoinjector method more favorably for time required for training, ease of use, convenience, satisfaction with weight-based dosing, risk of dosing errors, and speed of administration (p<0.001 for all comparisons). However, manual injection use was rated more favorably for risk of provider self-injury and patient cost (p<0.001 for both comparisons). Three participants (2%) reported a finger stick injury from an epinephrine autoinjector.

CONCLUSION

ED healthcare providers preferred the autoinjector method of IM epinephrine administration for the management of anaphylaxis or allergic reactions. Epinephrine autoinjector use may reduce barriers to epinephrine administration for the management of anaphylaxis in the ED.

Self-medication of anaphylactic reactions due to Hymenoptera stings-an EAACI Task Force Consensus Statement

An anaphylactic reaction due to a Hymenoptera sting is a clinical emergency, and patients, their caregivers as well as all healthcare professionals should be familiar with its recognition and acute management. This consensus report has been prepared by a European expert panel of the EAACI Interest Group of Insect Venom Hypersensitivity. It is targeted at allergists, clinical immunologists, internal medicine specialists, pediatricians, general practitioners, emergency department doctors, and any other healthcare professional involved. The aim was to report the scientific evidence on self-medication of anaphylactic reactions due to Hymenoptera stings, to inform healthcare staff about appropriate patient self-management of sting reactions, to propose indications for the prescription of an adrenaline auto-injector (AAI), and to discuss other forms of medication. First-line treatment for Hymenoptera sting anaphylaxis is intramuscular adrenaline. Prescription of AAIs is mandatory in the case of venom-allergic patients who suffer from mast cell diseases or with an elevated baseline serum tryptase level and in untreated patients with a history of a systemic reaction involving at least two different organ systems. AAI prescription should also be considered in other specific situations before, during, and after stopping venom immunotherapy.

Do epinephrine auto-injectors have an unsuitable needle length in children and adolescents at risk for anaphylaxis from food allergy?

Background

Food allergy is the most common cause of anaphylaxis in children. Intramuscular delivery of epinephrine auto-injectors (EAI) is the standard of care for the treatment of anaphylaxis. We examined if children and adolescents at risk of anaphylaxis weighing 15–30 kg and >30 kg would receive epinephrine into the intramuscular space with the currently available EAI in North America and Europe.

Methods

The distance from skin to muscle (STMD) and skin to bone (STBD) on the mid third anterolateral area of the right thigh was measured by ultrasound applying either high pressure (_max) or slight pressure (_min) in 102 children weighing 15–30 kg (group 1) and 100 children and adolescents, weighing more than 30 kg (group 2).

Results

Using a high pressure EAI (HPEAI), Epipen Jr^® and Auvi-Q^®/Allerject^® 0.15 mg, 11/102 (11 %) children in group 1 and 38/102 (38 %) using another HPEAI, Jext^®, had a STMD_max that showed a risk of intraosseous injection. There was a 1 % risk of subcutaneous injection with these devices. There was no risk of intraosseous injection using a low pressure EAI (LPEAI), Emerade^®. In group 2, the risk of intraosseous injection using a HPEAI was 3 % and no risk using a LPEAI. However, the risk of subcutaneous injection using HPEAI was 9 % and using LPEAI was 2 %.

Conclusion

There is a risk of intraosseous injection using HPEAI (Epipen^®/Epipen Jr^®, Auvi-Q^®/Allerject^® and especially Jext^®) in children at risk of anaphylaxis. There was also a risk of subcutaneous injection using the currently available HPEAI in children and adolescents.

Electronic supplementary material

The online version of this article (doi:10.1186/s13223-016-0110-8) contains supplementary material, which is available to authorized users.

Addressing barriers to emergency anaphylaxis care: from emergency medical services to emergency department to outpatient follow-up

BACKGROUND

Anaphylaxis is a systemic life-threatening allergic reaction that presents unique challenges for emergency care practitioners. Allergists and emergency physicians have a history of collaborating to promote an evidence-based, multidisciplinary approach to improve the emergency management and follow-up of patients with or at risk of anaphylaxis.

OBJECTIVES

To review recent scientific literature about anaphylaxis, discuss barriers to care, and recommend strategies to support improvement in emergency anaphylaxis care.

METHODS

An expert panel of allergists and emergency physicians was convened by the American College of Allergy, Asthma and Immunology in November 2014 to discuss current knowledge about anaphylaxis, identify opportunities for emergency practitioners and allergists to partner to address barriers to care, and recommend strategies to improve medical management of anaphylaxis along the continuum of care: from emergency medical systems and emergency department practitioners for acute management through appropriate outpatient follow-up with allergists to confirm diagnosis, identify triggers, and plan long-term care.

RESULTS

The panel identified key barriers to anaphylaxis care, including difficulties in making an accurate diagnosis, low rates of epinephrine administration during acute management, and inadequate follow-up. Strategies to overcome these barriers were discussed and recommendations made for future allergist/emergency physician collaborations, and key messages to be communicated to emergency practitioners were proposed.

CONCLUSION

The panel recommended that allergists and emergency physicians continue to work in partnership, that allergists be proactive in outreach to emergency care practitioners, and that easy-to-access educational programs and materials be developed for use by emergency medical systems and emergency department practitioners in the training environment and in practice.

CSACI position statement: epinephrine auto-injectors and children < 15 kg

Epinephrine (adrenaline) is the treatment of choice for anaphylaxis. While other medications, including H₁-antihistamines, H₂-antihistamines, corticosteroids, and inhaled beta-2 agonists are often used to treat anaphylaxis in the emergency setting, none of these medications has been shown to reverse anaphylaxis. Fatal anaphylaxis is related to the delayed use of epinephrine. In community settings, epinephrine is available as an auto-injector in two doses, 0.15 mg and 0.3 mg. The recommended dose for children is 0.01 mg per kilogram. For infants at risk of anaphylaxis in the community, there are few options with regard to providing an optimal epinephrine dose for first-aid treatment. The Canadian Society of Allergy and Immunology (CSACI) therefore recommends, for the child weighing less than 15 kg, given the lack of a suitable alternative, prescribing the 0.15 mg epinephrine autoinjector. Adverse effects of an epinephrine dose of 0.15 mg given intramuscularly in infants or children weighing less than 15 kg are expected to be mild and transient at the plasma epinephrine concentrations achieved; therefore, these effects need to be measured against the consequences of not receiving epinephrine at all, which can include fatality.

Excess subcutaneous tissue may preclude intramuscular delivery when using adrenaline autoinjectors in patients with anaphylaxis

Intramuscular adrenaline is the gold standard treatment for anaphylaxis. Intramuscular injection provides more rapid and higher plasma concentrations than subcutaneous routes. Given the increasing epidemic of obesity patients are at increased risk of subcutaneous delivery, we therefore assessed the depth of subcutaneous tissue in a population of patients with anaphylaxis. Patients already prescribed adrenaline autoinjectors (AAIs) for anaphylaxis were examined with ultrasound, and measurements of skin-to-muscle depth (STMD) at anterolateral thigh and anterior thigh were performed. Twenty-eight patients (23 female, 5 male) with an age range of 18-75 took part in the study, and in 68%, the STMD was greater than AAI needle length (15.02 mm), using the anterolateral thigh as the recommended administration site. The key predictors for increased STMD were female gender (P=0.0003) and a BMI > 30 (P=0.04). AAIs require longer needles to ensure intramuscular administration, and ultrasound at point of prescription would aid needle length selection.

Wilderness Medical Society practice guidelines for the use of epinephrine in outdoor education and wilderness settings: 2014 update

The Epinephrine Roundtable took place on July 27, 2008, during the 25th Annual Meeting of the Wilderness Medical Society (WMS) in Snowmass, CO. The WMS convened this roundtable to explore areas of consensus and uncertainty in the field treatment of anaphylaxis. Panelists were selected on the basis of their relevant academic or professional experience. There is a paucity of data that address the treatment of anaphylaxis in the wilderness. Anaphylaxis is a rare disease, with a sudden onset and drastic course that does not lend itself to study in randomized, controlled trials. Therefore, the panel endorsed the following position based on the limited available evidence and review of published articles, as well as expert consensus. The position represents the consensus of the panelists and is endorsed by the WMS. In 2014, the authors reviewed relevant articles published since the Epinephrine Roundtable. The following is an updated version of the original guidelines published in Wilderness & Environmental Medicine 2010;21(4):185-187.

Children under 15 kg with food allergy may be at risk of having epinephrine auto-injectors administered into bone

Background

The Epipen® Jr and Allerject® 0.15 mg are currently the most commonly prescribed epinephrine auto-injectors (EAIs) for the management of anaphylaxis in pediatric patients in North America and Canada. To ensure rapid absorption, it should be administered intramuscularly into the anterolateral aspect of the thigh. We examined whether the 12.7-mm needle length of the Epipen® Jr and Allerject® 0.15 mg is adequate for delivering epinephrine intramuscularly in pediatric patients who weighed <15 kg.

Methods

Consecutive pediatric patients with food allergy weighing <15 kg who required an EAI were included. Ultrasounds of the mid-anterolateral thigh were performed under minimal (min) and maximal (max) pressure. Skin-to-muscle depth (STMD) and skin-to-bone depth (STBD) measurements were completed. Baseline characteristics were compared between patients with a STBD_max <12.7 mm vs. ≥12.7 mm. Linear regression including variables such as age, sex, body mass index (BMI) and race was performed. The proportion of patients with a STBD_max <12.7 mm was compared in those weighing <10 kg vs. 10–14.9 kg.

Results

One hundred patients were included; 29 (29%) had STBD_max <12.7 mm. Height (p = 0.02) and weight (p = 0.0002) differed significantly between the two groups. Approximately 19% of those weighing 10–14.9 kg and 60% of those <10 kg had a STBD_max <12.7 mm. In the multivariable regression analysis, BMI was found to be a significant predictor of STBD_max.

Conclusions

A large proportion of children <15 kg prescribed an EAI is at risk of having the auto-injector administered into bone. Since alternative EAIs with shorter needle lengths are not currently available, EAIs should be prescribed with appropriate counselling in this population.

Anaphylaxis after vaccination of children: review of literature and recommendations for vaccination in child and school health services in Belgium

BACKGROUND

Concerns about the very small, but real risk of anaphylaxis after vaccination, has given rise to specific questions about the safe administration of vaccines to children and adolescents in the context of preventive settings (i.e. well baby clinics and school health services). As a support to preventive health professionals a guideline based on scientific evidence and supported by professional consensus was developed in Belgium.

METHODS

First, a draft of guideline was written based on a review of international literature. Second, through several rounds of consultation professional consensus about the document was obtained across the Belgian communities and professional groups, and in a final version endorsed by the Belgian Superior Health Council in July 2012.

RESULTS

In a literature overview information is given about the definition of anaphylaxis, allergens in vaccines potentially causing anaphylaxis, published incidence rates of anaphylaxis after vaccination, and strategies for first-aid management of anaphylaxis. The Belgian guideline on the prevention of anaphylaxis after vaccination includes recommendations on prevaccination risk assessment, the content of the emergency kit, measures to be taken after vaccination, differential diagnosis and first-aid management of anaphylaxis.

CONCLUSION

The guideline, summarized as a flowchart for the prevention and first-aid management of anaphylaxis, is considered as the actual state of the art in Belgium for vaccination of children and youngsters in preventive health services, and may inspire governmental bodies and/or professional groups in other countries to adopt similar recommendations.

Predictors of epinephrine autoinjector needle length inadequacy

BACKGROUND

Self-administered epinephrine is the primary out-of-hospital treatment of anaphylaxis. Intramuscular injection of epinephrine results in higher peak plasma concentration than subcutaneous injection. With the prevalence of obesity, autoinjectors may not have an adequate needle length for intramuscular injection.

OBJECTIVES

To measure muscle depth and evaluate predictors of autoinjector needle length inadequacy.

METHODS

We performed a prospective cross-sectional study of a convenience sample of low acuity emergency department patients aged 18 to 55 years. We recorded demographic data, measured thigh circumference, and calculated body mass index (BMI). Using ultrasound, we took depth-to-muscle measurements of the vastus lateralus in a standing position, with and without gentle pressure to simulate muscle compression that occurs with correct autoinjector use. We conducted univariate analyses using χ(2) and t tests with P ≤ .05 and 95% confidence intervals. We considered the patient a potential "failure" risk if his/her muscle depth exceeded 15.9 mm (longest available epinephrine autoinjectors needle).

RESULTS

We enrolled 120 subjects with a mean BMI of 29.2 kg/m(2). Thirty-one percent (31%) of our sample were found to be failure risks (36/116; confidence interval, 22.6%-39.5%). Women were 6.4 times more likely than men to be a failure risk (54.4% vs 5% for men failure rate; P < .001). Failures were more likely to be shorter, have a higher BMI, and have larger thigh circumference (P < .001). We did not find any statistical difference in muscle depth for race, age, or weight.

CONCLUSION

The current epinephrine autoinjector needle length is inadequate for intramuscular injection, especially among women.

Anaphylaxis in dogs and cats

OBJECTIVE

To review and summarize current information regarding the pathophysiology and clinical manifestations associated with anaphylaxis in dogs and cats. The etiology, diagnosis, treatment, and prognosis is discussed.

ETIOLOGY

Anaphylaxis is a systemic, type I hypersensitivity reaction that often has fatal consequences. Many of the principal clinical manifestations involve organs where mast cell concentrations are highest: the skin, the lungs, and the gastrointestinal tract. Histamine and other deleterious inflammatory mediators promote vascular permeability and smooth muscle contraction; they are readily released from sensitized mast cells and basophils challenged with antigen. Anaphylaxis may be triggered by a variety of antigens including insect and reptile venom, a variety of drugs, vaccines, and food.

DIAGNOSIS

Anaphylaxis is a clinical diagnosis made from a collection of signs and symptoms. It is most commonly based on pattern recognition. Differential diagnoses include severe asthma, pheocromocytoma, and mastocytosis.

THERAPY

Epinephrine is considered the drug of choice for the treatment of anaphylaxis. It acts primarily as a vasopressor in improving hemodynamic recovery. Adjunctive treatments include fluid therapy, H1 and H2 antihistamines, corticosteroids, and bronchodilators; however, these do not substitute for epinephrine.

PROGNOSIS

Prognosis depends on the severity of the clinical signs. The clinical signs will vary among species and route of exposure. The most severe clinical reactions are associated when the antigen is administered parenterally.

Anaphylaxis in children: current understanding and key issues in diagnosis and treatment

Anaphylaxis is a severe allergic reaction that is rapid in onset and may cause death. Since it is unpredictable and potentially fatal, prompt recognition and treatment are vital to maximize a positive outcome. The occurrence of anaphylaxis is increasing across all ages in the United States, with increased risk of worse outcome in teenagers/young adults and in those with comorbid conditions such as asthma. Gaps in the assessment of patient-specific risk factors, identification and prevention of triggers, recognition of signs/symptoms, and pharmacologic treatment of anaphylaxis have been identified at the physician and caregiver/patient level. A PubMed literature search (January 2000–December 2011) was conducted to identify publications on childhood anaphylaxis using the following terms: food allergy, food allergens, food hypersensitivity, epinephrine, epinephrine auto-injectors, anaphylactic triggers, and anaphylaxis. This review will critically appraise these key issues and highlight strategies that might result in improved management of anaphylaxis in children.

Adrenaline auto-injectors for the treatment of anaphylaxis with and without cardiovascular collapse in the community

BACKGROUND

Anaphylaxis is a serious hypersensitivity reaction that is rapid in onset and may cause death. Adrenaline (epinephrine) auto-injectors are recommended as the initial, potentially life-saving treatment of choice for anaphylaxis in the community, but they are not universally available and have limitations in their use.

OBJECTIVES

To assess the effectiveness of adrenaline (epinephrine) auto-injectors in relieving respiratory, cardiovascular, and other symptoms during episodes of anaphylaxis that occur in the community.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (Ovid SP) (1950 to January 2012), EMBASE (Ovid SP) (1980 to January 2012 ), CINAHL (EBSCO host) (1982 to January 2012 ), AMED (EBSCO host) (1985 to January 2012 ), LILACS, (BIREME) (1980 to January 2012 ), ISI Web of Science (1950 to January 2012 ). We adapted our search terms for other databases. We also searched websites listing on-going trials: the World Health Organization International Clinical Trials Registry Platform, the UK Clinical Research Network Study Portfolio, and the meta Register of Controlled Trials; and contacted pharmaceutical companies who manufacture adrenaline auto-injectors in an attempt to locate unpublished material.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing auto-injector administration of adrenaline with any control including no intervention, placebo, or other adrenergic agonists were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed articles for inclusion.

MAIN RESULTS

None of the 1328 studies that were identified satisfied the inclusion criteria.

AUTHORS' CONCLUSIONS

Based on this review, we cannot make any new recommendations on the effectiveness of adrenaline auto-injectors for the treatment of anaphylaxis. Although randomized, double-blind, placebo-controlled clinical trials of high methodological quality are necessary to define the true extent of benefits from the administration of adrenaline in anaphylaxis via an auto-injector, such trials are unlikely to be performed in individuals experiencing anaphylaxis because of ethical concerns associated with randomization to placebo. There is, however, a need to consider trials in which, for example, auto-injectors of different doses of adrenaline and differing devices are compared in order to provide greater clarity on the dose and device of choice. Such trials would be practically challenging to conduct. In the absence of appropriate trials, we recommend that adrenaline administration by auto-injector should still be regarded as the most effective first-line treatment for the management of anaphylaxis in the community. In countries where auto-injectors are not commonly used, it may be possible to conduct trials to compare administration of adrenaline via auto-injector with adrenaline administered by syringe and ampoule, or comparing the effectiveness of two different types of auto-injector.

The TEN study: time epinephrine needs to reach muscle

BACKGROUND

An epinephrine autoinjector (EAI) is designed to deliver epinephrine into the vastus lateralis muscle. Several studies have demonstrated both patient and physician difficulties in correctly using EAIs, specifically premature removal of the device from the thigh.

OBJECTIVE

To evaluate the correlation between duration of injection with an EAI and amount of epinephrine absorbed into muscle tissue.

METHODS

Twenty-one EAI devices (0.3 mL) were used to determine the amount of epinephrine injected into marbleized beef during 7 time periods. A digital scale was used to record preinjection and postinjection weights of EAIs and beef. The weight difference between the preinjection and postinjection periods of the EAIs was used to calculate the total amount of epinephrine released and available for absorption into the marbleized beef. The difference between the preinjection and postinjection beef weight was used to determine the amount of epinephrine absorbed into the meat.

RESULTS

The correlation with duration of injection for both the amount of epinephrine absorbed and released was 0.321 (P = .48). At all intervals, 95.9% or more of epinephrine was absorbed into the marbleized beef. The correlation with duration of injection and percent of epinephrine absorbed was 0.464 (P = .29). There were no time periods that were significantly different from the percentage of epinephrine absorbed by the marbleized beef at 10 seconds (analysis of variance P = .16).

CONCLUSION

No linear relationship between time and amount of epinephrine injected or absorbed into muscle tissue was demonstrated. These data suggest that holding the device in place for 1 second is as effective as 10 seconds.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

What are the 'ideal' features of an adrenaline (epinephrine) auto-injector in the treatment of anaphylaxis?

Anaphylaxis is a systemic allergic reaction that often involves respiratory symptoms and cardiovascular collapse, which are potentially life-threatening if not treated promptly with intramuscular adrenaline. Owing to the unpredictable nature of anaphylaxis and accidental exposure to allergens (such as peanuts and shellfish), patients should be prescribed intramuscular adrenaline auto-injectors and carry these with them at all times. Patients also need to be able to use their auto-injectors correctly while under high stress, when an anaphylactic attack occurs. Despite this, an alarming number of patients fail to carry their auto-injectors and many patients, carers of children with known anaphylaxis and healthcare professionals do not know how to use the device correctly, despite having had training. Currently available auto-injector devices have various limitations that may impede their use in the management of anaphylaxis. There is also a lack of validated assessment criteria and regulatory requirements for new devices. This review describes the different delivery systems used in currently available auto-injectors and discusses the key barriers to the use of adrenaline auto-injectors, with the goal of identifying the 'ideal' features/characteristics of such devices in the emergency treatment of anaphylaxis that will ensure ease of use, portability and accurate delivery of a life-saving drug.

Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel

Food allergy is an important public health problem that affects children and adults and may be increasing in prevalence. Despite the risk of severe allergic reactions and even death, there is no current treatment for food allergy: the disease can only be managed by allergen avoidance or treatment of symptoms. The diagnosis and management of food allergy also may vary from one clinical practice setting to another. Finally, because patients frequently confuse nonallergic food reactions, such as food intolerance, with food allergies, there is an unfounded belief among the public that food allergy prevalence is higher than it truly is. In response to these concerns, the National Institute of Allergy and Infectious Diseases, working with 34 professional organizations, federal agencies, and patient advocacy groups, led the development of clinical guidelines for the diagnosis and management of food allergy. These Guidelines are intended for use by a wide variety of health care professionals, including family practice physicians, clinical specialists, and nurse practitioners. The Guidelines include a consensus definition for food allergy, discuss comorbid conditions often associated with food allergy, and focus on both IgE-mediated and non-IgE-mediated reactions to food. Topics addressed include the epidemiology, natural history, diagnosis, and management of food allergy, as well as the management of severe symptoms and anaphylaxis. These Guidelines provide 43 concise clinical recommendations and additional guidance on points of current controversy in patient management. They also identify gaps in the current scientific knowledge to be addressed through future research.

Are adrenaline autoinjectors fit for purpose? A pilot study of the mechanical and injection performance characteristics of a cartridge-versus a syringe-based autoinjector

Background:

Adrenaline autoinjectors (AAIs) are prescribed to facilitate the intramuscular administration of adrenaline in patients diagnosed with life-threatening anaphylaxis. This pilot study investigated the injection and functional properties of two AAIs (deploying different delivery systems) under standard conditions, after dynamic and mechanical stresses, and in the presence of denim.

Methods:

The differences between a cartridge-based AAI (EpiPen^® Junior) and a syringe-based AAI (Anapen^® Junior) were assessed using three sets of tests. Test 1: under standard conditions, the injection depth and dose were measured in ballistic gelatine (a validated tissue simulant). Test 2: before the safety cap removal and activation forces were measured, AAIs were subjected to either of two preconditioning tests: 1) free-fall drop test; or 2) static load (ie, 400 N, equivalent to 40 kg weight) test; or 3) no preconditioning. Test 3: under standard conditions, injection properties into ballistic gelatine in the presence and absence of denim were investigated. Statistical analyses were performed using the Student’s t-test or Welch’s test.

Results:

The maximum depth of delivery was significantly greater with cartridge AAI (n = 4, mean 21.09 ± 2.54 mm) than with syringe AAI (n = 5; mean 11.64 ± 0.80 mm; P = 0.003). After 2.5 seconds, cartridge AAI (n = 4) discharged significantly more dose than syringe AAI (n = 3; 74.3% versus 25.7% of total dose; P = 0.001). Both cartridge and syringe AAI withstood the free-fall drop test, but almost all devices failed to activate following the static load test. Under standard conditions, significantly less force was required to remove the safety cap of cartridge AAI than syringe AAI (both n = 15; mean 9.56 ± 2.36 N versus 20.23 ± 6.61 N, respectively; P < 0.001), but a significantly greater activation force was required for cartridge AAI than syringe AAI (mean 23.01 ± 3.96 N versus 8.06 ± 0.51 N, respectively; P < 0.001). The presence of denim did not alter the activation force or effective needle length of either of the AAIs.

Conclusion:

Cartridge AAI appears significantly more capable of consistently and rapidly delivering a clinically relevant dose of intramuscular adrenaline than syringe AAI. However, both devices showed shortcomings in their ability to sustain mechanical stress similar to that which is likely over their shelf life, and as such, may not be fit for life-saving purpose.

Anaphylaxis: Recent advances in assessment and treatment

The incidence rate of anaphylaxis is increasing, particularly during the first 2 decades of life. Common triggers include foods, medications, and insect stings. Clinical diagnosis is based on a meticulous history of an exposure or event preceding characteristic symptoms and signs, sometimes but not always supported by a laboratory test such as an elevated serum total tryptase level. Physician-initiated investigation of patients with anaphylaxis whose symptoms and signs are atypical sometimes leads to important insights into previously unrecognized triggers and mechanisms. In idiopathic anaphylaxis, in which no trigger can be confirmed by means of skin testing or measurement of specific IgE, the possibility of mastocytosis or a clonal mast cell disorder must be considered in addition to the possibility of a previously unrecognized trigger. Long-term risk reduction in patients with anaphylaxis focuses on optimal management of relevant comorbidities such as asthma and other respiratory diseases, cardiovascular disease, and mastocytosis or a clonal mast cell disorder; avoidance of the relevant confirmed allergen trigger; and relevant immunomodulation such as medication desensitization, venom immunotherapy, and possibly in the future, immunotherapy with food. Emergency preparedness for recurrence of anaphylaxis in community settings includes having epinephrine (adrenaline) autoinjectors available, knowing when and how to use them, and having a written, personalized anaphylaxis emergency action plan and up-to-date medical identification. Randomized controlled trials of the pharmacologic interventions used in an acute anaphylaxis episode are needed.