Showing papers on "Epinephrine published in 2020"

Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis.

Abstract: Anaphylaxis is an acute, potential life-threatening systemic allergic reaction that may have a wide range of clinical manifestations. Severe anaphylaxis and/or the need for repeated doses of epinephrine to treat anaphylaxis are risk factors for biphasic anaphylaxis. Antihistamines and/or glucocorticoids are not reliable interventions to prevent biphasic anaphylaxis, although evidence supports a role for antihistamine and/or glucocorticoid premedication in specific chemotherapy protocols and rush aeroallergen immunotherapy. Evidence is lacking to support the role of antihistamines and/or glucocorticoid routine premedication in patients receiving low- or iso-osmolar contrast material to prevent recurrent radiocontrast media anaphylaxis. Epinephrine is the first-line pharmacotherapy for uniphasic and/or biphasic anaphylaxis. After diagnosis and treatment of anaphylaxis, all patients should be kept under observation until symptoms have fully resolved. All patients with anaphylaxis should receive education on anaphylaxis and risk of recurrence, trigger avoidance, self-injectable epinephrine education, referral to an allergist, and be educated about thresholds for further care.

Adrenergic regulation of immune cell function and inflammation.

Abstract: The sympathetic nervous system integrates the functions of multiple organ systems by regulating their autonomic physiological activities. The immune system is regulated both locally and systemically by the neurotransmitters epinephrine and norepinephrine secreted by the adrenal gland and local sympathetic neurons. Immune cells respond by activation of adrenergic receptors, primarily the β2-adrenergic receptor, which signal through heterotrimeric G-proteins. Depending upon the cell type, adrenergic signaling regulates a variety of functions in immune cells ranging from cellular migration to cytokine secretion. Furthermore, due to the diurnal oscillation of systemic norepinephrine levels, various immune functions follow a circadian rhythmic pattern. This review will highlight recent advances in our understanding of how the sympathetic nervous system regulates both innate and adaptive immune functions and how this regulation is linked to circadian rhythms.

Catecholamines Induce Trained Immunity in Monocytes In Vitro and In Vivo

Abstract: Rationale: Exposure to high catecholamine levels is associated with inflammatory changes of myeloid cells and atherosclerosis, but the underlying mechanisms are only partly understood. Objective: T...

Epinephrine's effects on cerebrovascular and systemic hemodynamics during cardiopulmonary resuscitation.

Abstract: Despite controversies, epinephrine remains a mainstay of cardiopulmonary resuscitation (CPR). Recent animal studies have suggested that epinephrine may decrease cerebral blood flow (CBF) and cerebral oxygenation, possibly potentiating neurological injury during CPR. We investigated the cerebrovascular effects of intravenous epinephrine in a swine model of pediatric in-hospital cardiac arrest. The primary objectives of this study were to determine if (1) epinephrine doses have a significant acute effect on CBF and cerebral tissue oxygenation during CPR and (2) if the effect of each subsequent dose of epinephrine differs significantly from that of the first. One-month-old piglets (n = 20) underwent asphyxia for 7 min, ventricular fibrillation, and CPR for 10–20 min. Epinephrine (20 mcg/kg) was administered at 2, 6, 10, 14, and 18 min of CPR. Invasive (laser Doppler, brain tissue oxygen tension [PbtO2]) and noninvasive (diffuse correlation spectroscopy and diffuse optical spectroscopy) measurements of CBF and cerebral tissue oxygenation were simultaneously recorded. Effects of subsequent epinephrine doses were compared to the first. With the first epinephrine dose during CPR, CBF and cerebral tissue oxygenation increased by > 10%, as measured by each of the invasive and noninvasive measures (p < 0.001). The effects of epinephrine on CBF and cerebral tissue oxygenation decreased with subsequent doses. By the fifth dose of epinephrine, there were no demonstrable increases in CBF of cerebral tissue oxygenation. Invasive and noninvasive CBF measurements were highly correlated during asphyxia (slope effect 1.3, p < 0.001) and CPR (slope effect 0.20, p < 0.001). This model suggests that epinephrine increases CBF and cerebral tissue oxygenation, but that effects wane following the third dose. Noninvasive measurements of neurological health parameters hold promise for developing and directing resuscitation strategies.

Macrophage-mediated regulation of catecholamines in sympathetic neural remodeling after myocardial infarction

Abstract: Sympathetic neural remodeling, which involves the inflammatory response, plays an important role in ventricular arrhythmias (VAs) after myocardial infarction (MI). Adrenergic receptors on macrophages potentially modulate the inflammatory response. We hypothesized that the increased level of catecholamines activates macrophages and regulates sympathetic neural remodeling after MI. We treated MI mice with either clodronate or metoprolol for 5 days following coronary artery ligation. Mice without treatment after MI and sham-operation mice served as the positive control and negative control, respectively. The norepinephrine levels in plasma and the peri-infarct myocardium increased by almost two-fold in the MI mice compared with the sham-operation mice. Both in vivo and ex vivo electrophysiology examinations showed that the vulnerability to VAs induced by MI was alleviated by macrophage depletion with clodronate and β1-adrenergic blockade with metoprolol, which was in line with circulating and peri-infarct norepinephrine levels, sympathetic reinnervation, and the expression of nerve growth factor (NGF) 7 days after surgery. To further verify the interaction between catecholamines and macrophages, we preconditioned lipopolysaccharide-stimulated RAW 264.7 cells using epinephrine or epinephrine with selective adrenergic antagonists. The expression and release of inflammatory factors including NGF were enhanced by epinephrine. This effect was inhibited by metoprolol but not by other subtype antagonists. Our data suggested that the increased level of catecholamines, traditionally known as positive inotropes secreted from sympathetic nerve endings, might regulate cardiac sympathetic neural remodeling through β1-adrenergic receptors on macrophages, subsequently inducing VAs after MI.

Epinephrine for Out-of-Hospital Cardiac Arrest: An Updated Systematic Review and Meta-Analysis.

Abstract: Objectives To perform an updated systematic review and meta-analysis of clinical trials evaluating epinephrine for adult out-of-hospital cardiac arrest resuscitation. Data sources The search included MEDLINE, EMBASE, and Ovid Evidence-Based Medicine, clinical trial registries, and bibliographies. Study selection Randomized and quasi-randomized controlled trials that compared the current standard dose of epinephrine to placebo, high or low dose epinephrine, any other vasopressor alone or in combination were screened by three independent reviewers. Data extraction Randomized and quasi-randomized controlled trials that compared the current standard dose of epinephrine to placebo, high or low dose epinephrine, any other vasopressor alone or in combination were screened by three independent reviewers. Data synthesis A total of 17 trials (21,510 patients) were included; seven were judged to be at high risk of bias. Compared to placebo, pooled results from two trials showed that standard dose of epinephrine increased return of spontaneous circulation (risk ratio, 3.09; 95% CI, 2.82-3.89), survival to hospital admission (risk ratio, 2.50; 95% CI, 1.68-3.72), and survival to discharge (risk ratio, 1.44; 95% CI, 1.11-1.86). The largest placebo-controlled trial showed that standard dose of epinephrine also improved survival at 30 days and 3 months but not neurologic outcomes, standard dose of epinephrine decreased return of spontaneous circulation (risk ratio, 0.87; 95% CI, 0.77-0.98) and survival to admission (risk ratio, 0.88; 95% CI, 0.78-0.99) when compared with high dose epinephrine. There were no differences in outcomes between standard dose of epinephrine and vasopressin alone or in combination with epinephrine. Conclusions Largely based on one randomized controlled trial, standard dose of epinephrine improved overall survival but not neurologic outcomes in out-of-hospital cardiac arrest patients compared with placebo. There is a paucity of trials with meaningful patient outcomes; future epinephrine trials should evaluate dose and method of delivery on long-term survival, neurologic function, and quality of life after cardiac arrest.

Blood norepinephrine/epinephrine/dopamine measurements in 108 patients with takotsubo syndrome from the world literature: pathophysiological implications

Abstract: Release of norepinephrine (NE) from neuronal cardiac nerve endings and/or blood-borne catecholamines (CATs), mainly epinephrine (EPI), may mediate TTS. The aim of this study was to document the lev...

Hypoglycemic thalamic activation in type 1 diabetes is associated with preserved symptoms despite reduced epinephrine.

Abstract: Brain responses to low plasma glucose may be key to understanding the behaviors that prevent severe hypoglycemia in type 1 diabetes. This study investigated the impact of long duration, hypoglycemia aware type 1 diabetes on cerebral blood flow responses to hypoglycemia. Three-dimensional pseudo-continuous arterial spin labeling magnetic resonance imaging was performed in 15 individuals with type 1 diabetes and 15 non-diabetic controls during a two-step hyperinsulinemic glucose clamp. Symptom, hormone, global cerebral blood flow and regional cerebral blood flow responses to hypoglycemia were measured. Epinephrine release during hypoglycemia was attenuated in type 1 diabetes, but symptom score rose comparably in both groups. A rise in global cerebral blood flow did not differ between groups. Regional cerebral blood flow increased in the thalamus and fell in the hippocampus and temporal cortex in both groups. Type 1 diabetes demonstrated lesser anterior cingulate cortex activation; however, this difference did not survive correction for multiple comparisons. Thalamic cerebral blood flow change correlated with autonomic symptoms, and anterior cingulate cortex cerebral blood flow change correlated with epinephrine response across groups. The thalamus may thus be involved in symptom responses to hypoglycemia, independent of epinephrine action, while anterior cingulate cortex activation may be linked to counterregulation. Activation of these regions may have a role in hypoglycemia awareness and avoidance of problematic hypoglycemia.

Differential Effects of Acute Treatment With Antipsychotic Drugs on Peripheral Catecholamines.

Abstract: Antipsychotic drugs represent the most effective treatment for chronic psychotic disorders. The newer second generation drugs offer the advantage of fewer neurological side-effects compared to prior drugs, but many cause serious metabolic side-effects. The underlying physiology of these side-effects is not well-understood, but evidence exists to indicate that the sympathetic nervous system may play an important role. In order to examine this possibility further, we treated separate groups of adult female rats acutely with either the first generation antipsychotic drug haloperidol (0.1 or 1 mg/kg) or the second generation drugs risperidone (0.25 or 2.5 mg/kg), clozapine (2 or 20 mg/kg), olanzapine (3 or 15 mg/kg) or vehicle by intraperitoneal injection. Blood samples were collected prior to drug and then 30, 60, 120, and 180 mins after treatment. Plasma samples were assayed by HPLC-ED for levels of norepinephrine, epinephrine, and dopamine. Results confirmed that all antipsychotics increased peripheral catecholamines, although this was drug and dose dependent. For norepinephrine, haloperidol caused the smallest maximum increase (+158%], followed by risperidone (+793%), olanzapine (+952%) and clozapine (+1,684%). A similar pattern was observed for increases in epinephrine levels by haloperidol (+143%], olanzapine (+529%), risperidone (+617%) then clozapine (+806%). Dopamine levels increased moderately with olanzapine [+174%], risperidone [+271%], and clozapine [+430%]. Interestingly, levels of the catecholamines did not correlate strongly with each other prior to treatment at baseline, but were increasingly correlated after treatment as time proceeded. The results demonstrate antipsychotics can potently regulate peripheral catecholamines, in a manner consistent with their metabolic liability.

Impact of concomitant vasoactive treatment and mechanical left ventricular unloading in a porcine model of profound cardiogenic shock.

Abstract: Concomitant vasoactive drugs are often required to maintain adequate perfusion pressure in patients with acute myocardial infarction (AMI) and cardiogenic shock (CS) receiving hemodynamic support with an axial flow pump (Impella CP). To compare the effect of equipotent dosages of epinephrine, dopamine, norepinephrine, and phenylephrine on cardiac work and end-organ perfusion in a porcine model of profound ischemic CS supported with an Impella CP. CS was induced in 10 pigs by stepwise intracoronary injection of polyvinyl microspheres. Hemodynamic support with Impella CP was initiated followed by blinded crossover to vasoactive treatment with norepinephrine (0.10 μg/kg/min), epinephrine (0.10 μg/kg/min), or dopamine (10 μg/kg/min) for 30 min each. At the end of the study, phenylephrine (10 μg/kg/min) was administered for 20 min. The primary outcome was cardiac workload, a product of pressure-volume area (PVA) and heart rate (HR), measured using the conductance catheter technique. End-organ perfusion was assessed by measuring venous oxygen saturation from the pulmonary artery (SvO2), jugular bulb, and renal vein. Treatment effects were evaluated using multilevel mixed-effects linear regression. All catecholamines significantly increased LV stroke work and cardiac work, dopamine to the greatest extend by 341.8 × 103 (mmHg × mL)/min [95% CI (174.1, 509.5), p < 0.0001], and SvO2 significantly improved during all catecholamines. Phenylephrine, a vasoconstrictor, caused a significant increase in cardiac work by 437.8 × 103 (mmHg × mL)/min [95% CI (297.9, 577.6), p < 0.0001] due to increase in potential energy (p = 0.001), but no significant change in LV stroke work. Also, phenylephrine tended to decrease SvO2 (p = 0.063) and increased arterial lactate levels (p = 0.002). Catecholamines increased end-organ perfusion at the expense of increased cardiac work, most by dopamine. However, phenylephrine increased cardiac work with no increase in end-organ perfusion.

Effect of Continuous Epinephrine Infusion on Survival in Critically Ill Patients: A Meta-Analysis of Randomized Trials.

Abstract: Objectives:Epinephrine is frequently used as an inotropic and vasopressor agent in critically ill patients requiring hemodynamic support. Data from observational trials suggested that epinephrine use is associated with a worse outcome as compared with other adrenergic and nonadrenergic vasoactive dr

Treatment with a Platelet Activating Factor receptor antagonist improves hemodynamics and reduces epinephrine requirements, in a lethal rodent model of anaphylactic shock

Abstract: BACKGROUND In some cases, anaphylactic shock (AS) is still lethal, despite rapid use of epinephrine. High doses of epinephrine are associated with severe complications. Platelet-activating factor (PAF) is secreted in massive amounts during AS, and a high plasma level is correlated with increased AS severity. OBJECTIVE To assess the effect of ABT-491, a PAF-receptor antagonist and possible adjunct treatment, alone or in combination with epinephrine during AS. METHODS AS was induced by intravenous injection of 1 mg ovalbumin into ovalbumin-sensitized rats. Rats were then randomly assigned to 5 groups (n = 10 per group): SHAM (vehicle only), SHOCK (no treatment), ABT (ABT-491 1 mg/kg), EPI (epinephrine 5 µg as a bolus then 10 µg kg-1 min-1 by continuous infusion, followed by a reducing protocol) and EPI-ABT (both treatments). RESULTS Ovalbumin injection resulted in a severe decrease in mean arterial pressure, left ventricular inotropy (max dP/dt) and left ventricular shortening fraction (LVSF). All rats from the ABT group survived until the end of the experiment. ABT-491 prevented the LVSF decrease observed in the SHOCK group (at T15: ABT 50% ± 11% vs SHOCK 36% ± 9%, P = .01), significantly reduced the dose of epinephrine needed to treat anaphylactic shock (EPI-ABT 314 ± 67 µg/kg vs EPI 475 ± 69 µg/kg, P < .001) and reduced the time to restore basal MAP (ABT 23 ± 7 minutes vs EPI-ABT 13 ± 5 minutes, P < .01). CONCLUSIONS AND CLINICAL RELEVANCE AS was characterized by early cardiac dysfunction in our model. Treatment with ABT-491 allowed survival until the end of the experiment and reduced cardiac dysfunction. Use of the PAF-R antagonist had a synergistic effect with epinephrine and allowed a significant reduction in epinephrine consumption. Use of PAF-R antagonists during AS could reduce epinephrine-related complications and improve the treatment of epinephrine refractory cases.

Fast in vivo detection of myocardial norepinephrine levels in the beating porcine heart.

Abstract: The sympathetic nervous system modulates cardiac function by controlling key parameters such as chronotropy and inotropy. Sympathetic control of ventricular function occurs through extrinsic innervation arising from the stellate ganglia and thoracic sympathetic chain. In the healthy heart, sympathetic release of norepinephrine (NE) results in positive modulation of chronotropy, inotropy, and dromotropy, significantly increasing cardiac output. However, in the setting of myocardial infarction or injury, sympathetic activation persists, contributing to heart failure and increasing the risk of arrhythmias, including sudden cardiac death. Methodologies for detection of norepinephrine in cardiac tissue are limited. Present techniques rely on microdialysis for analysis by high-performance liquid chromatography coupled to electrochemical detection (HPLC-ED), radioimmunoassay, or other immunoassays, such as enzyme-linked immunosorbent assay (ELISA). Although significant information about the release and action of norepinephrine has been obtained with these methodologies, they are limited in temporal resolution, require large sample volumes, and provide results with a significant delay after sample collection (hours to weeks). In this study, we report a novel approach for measurement of interstitial cardiac norepinephrine, using minimally invasive, electrode-based, fast-scanning cyclic voltammetry (FSCV) applied in a beating porcine heart. The first multispatial and high temporal resolution, multichannel measurements of NE release in vivo are provided. Our data demonstrate rapid changes in interstitial NE profiles with regional differences in response to coronary ischemia, sympathetic nerve stimulation, and alterations in preload/afterload.NEW & NOTEWORTHY Pharmacological, electrical, or surgical regulation of sympathetic neuronal control can be used to modulate cardiac function and treat arrhythmias. However, present methods for monitoring sympathetic release of norepinephrine in the heart are limited in spatial and temporal resolution. Here, we provide for the first time a methodology and demonstration of practice and rapid measures of individualized regional autonomic neurotransmitter levels in a beating heart. We show dynamic, spatially resolved release profiles under normal and pathological conditions.

Epistasis between phenylethanolamine N-methyltransferase and β2-adrenergic receptor influences extracellular epinephrine level and associates with the susceptibility to allergic asthma.

Abstract: BACKGROUND Reduced extracellular epinephrine level often associates with asthma-related symptoms; however, the correlation between asthma and genetic variants in genes participating in the epinephrine signalling pathway remains unclear. OBJECTIVE To characterize the functions of single nucleotide polymorphisms (SNPs) in phenylethanolamine N-methyltransferase (PNMT) and β2-adrenergic receptor (ADRB2), and to study the effects, including both direct and epistatic, of these SNPs on serum epinephrine level and asthma susceptibility. METHODS Single nucleotide polymorphisms functions were characterized through in vitro luciferase assay. ADRB2 gene expression level in peripheral blood mononuclear cell (PBMC) was measured by transcriptome sequencing and expression microarray on two separate Asian cohorts (NUS-UTAR, n = 278 and NUS-TA, n = 58). Serum epinephrine level was assessed on a Singapore Chinese cohort (NUS-SH, n = 314) with 155 asthmatic and 159 non-asthmatic subjects. A separate Singapore Chinese cohort (NUS-G, n = 3009) was genotyped to show disease association (direct and epistatic effect) of functional SNPs in PNMT and ADRB2. RESULTS Reduced serum epinephrine level was associated with increased asthma risk in Singapore Chinese. The minor allele of rs876493 was shown to increase PNMT promoter activity and reduce asthma risk. Multiple SNPs in ADRB2 forms a haplotype that was associated with the differential promoter activity of this gene. In this haplotype, rs11168070 was associated directly with ADRB2 expression in PBMCs. Both minor alleles from rs876493 and rs11168070 contribute synergistically to reduce asthma risk and increase serum epinephrine level. CONCLUSION AND CLINICAL RELEVANCE Epistatic interaction between genetic variants from PNMT (rs876493) and ADRB2 (rs11168070) is associated with serum epinephrine level and the susceptibility of asthma. Our findings improved the current understanding of the genetic basis of this disease, while genotypic states of these SNPs may serve as potential biomarkers to predict susceptibility to the disease.

Usage of Epinephrine Mixed With Lidocaine in Plastic Surgery.

Abstract: Plastic surgeons commonly administer subcutaneous epinephrine to reduce intraoperative blood loss. The authors hypothesized that there are safe and effective concentration of epinephrine for vasoconstriction and their durations. The aim of this study is to summarize the existing literatures for the usage of epinephrine mixed with lidocaine in plastic surgical field.In 1903, Braun reported that adrenaline prolonged the local anesthetic effects of cocaine. The Parke-Davis Company began selling cocaine with adrenaline, as well as combining adrenaline with new synthetic local anesthetics.Based on a review of the literature, concentrations between 1:50,000 and 1:400,000 are equally effective and provide superior vasoconstriction compared with more dilute solutions. If epinephrine is further diluted, its onset and time to peak serum concentration are delayed, and its duration of action is shortened. When lidocaine is used without epinephrine, duration of anesthesia is shortened reverse proportionally to the lidocaine concentration. When lidocaine is used with epinephrine, duration of anesthesia is prolonged proportionally to the lidocaine concentration. With slow injection rate in the soft tissue, the maximum safe dose of lidocaine is approximately 3 mg/kg plain and 7 mg/kg when mixed with epinephrine. Lidocaine may protect the myocardium because of its antiarrhythmic activity, which is the rationale for infiltrating lidocaine mixed with epinephrine in general anesthesia.In plastic surgery, subcutaneous infiltration of epinephrine-lidocaine solution is performed to reduce intraoperative blood loss. Even in general anesthesia, infiltrating lidocaine mixed with epinephrine may protect the myocardium because of its antiarrhythmic activity.

A novel ultrasound-guided mouse model of sudden cardiac arrest.

Abstract: Aim Mouse models of sudden cardiac arrest are limited by challenges with surgical technique and obtaining reliable venous access. To overcome this limitation, we sought to develop a simplified method in the mouse that uses ultrasound-guided injection of potassium chloride directly into the heart. Methods Potassium chloride was delivered directly into the left ventricular cavity under ultrasound guidance in intubated mice, resulting in immediate asystole. Mice were resuscitated with injection of epinephrine and manual chest compressions and evaluated for survival, body temperature, cardiac function, kidney damage, and diffuse tissue injury. Results The direct injection sudden cardiac arrest model causes rapid asystole with high surgical survival rates and short surgical duration. Sudden cardiac arrest mice with 8-min of asystole have significant cardiac dysfunction at 24 hours and high lethality within the first seven days, where after cardiac function begins to improve. Sudden cardiac arrest mice have secondary organ damage, including significant kidney injury but no significant change to neurologic function. Conclusions Ultrasound-guided direct injection of potassium chloride allows for rapid and reliable cardiac arrest in the mouse that mirrors human pathology without the need for intravenous access. This technique will improve investigators’ ability to study the mechanisms underlying post-arrest changes in a mouse model.

Wide-Awake Surgery With Local Anesthesia and Epinephrine Is Safe

Abstract: Hand and upper extremity surgery performed with the patient wide awake involves the use of a local anesthetic and epinephrine. Controversy persists as to whether epinephrine is safe for use in the hand. The goal of this study was to evaluate the safety of epinephrine in hand and upper extremity surgery. The hypothesis was that epinephrine is safe and can be used for a wide breadth of surgical procedures of the hand and upper extremity. A 4-year retrospective chart review was conducted of consecutive patients undergoing wide-awake surgery performed by 2 surgeons at a single institution. All procedures were performed with local anesthesia and epinephrine. Data collected included patient demographics, procedure volume, procedure type, surgical setting, and complications related to epinephrine use. During the study period, 4054 consecutive patients underwent 4287 wide-awake procedures with local anesthesia and epinephrine. Average patient age was 59 years, and 64% of patients were female. No complications occurred as a result of the use of epinephrine, and no tissue necrosis, phentolamine reversal, anaphylaxis, or readmissions occurred. No patients required conversion to general anesthesia or monitored anesthesia care. This analysis of more than 4000 consecutive patients undergoing wide-awake hand and upper extremity surgery with epinephrine confirmed that epinephrine use is safe, with no reported cases of tissue necrosis, reversal, readmission, anaphylaxis, or anesthetic conversion. Epinephrine is safe for use in the hand and upper extremity for patients undergoing wide-awake hand surgery with a local anesthetic. [Orthopedics. 2020;43(6):e529-e532.].

Plasma Epinephrine Contributes to the Development of Experimental Hypoglycemia-Associated Autonomic Failure.

Abstract: BACKGROUND Recurrent hypoglycemia blunts counter-regulatory responses to subsequent hypoglycemic episodes, a syndrome known as hypoglycemia-associated autonomic failure (HAAF). Since adrenergic receptor blockade has been reported to prevent HAAF, we investigated whether the hypoglycemia-associated rise in plasma epinephrine contributes to pathophysiology and reported interindividual differences in susceptibility to HAAF. METHODS To assess the role of hypoglycemia-associated epinephrine responses in the susceptibility to HAAF, 24 adult nondiabetic subjects underwent two 2-hour hyperinsulinemic hypoglycemic clamp studies (nadir 54 mg/dL; 0-2 hours and 4-6 hours) on Day 1, followed by a third identical clamp on Day 2. We challenged an additional 7 subjects with two 2-hour infusions of epinephrine (0.03 μg/kg/min; 0-2 hours and 4-6 hours) vs saline on Day 1 followed by a 200-minute stepped hypoglycemic clamp (90, 80, 70, and 60 mg/dL) on Day 2. RESULTS Thirteen out of 24 subjects developed HAAF, defined by ≥20% reduction in average epinephrine levels during the final 30 minutes of the third compared with the first hypoglycemic episode (P < 0.001). Average epinephrine levels during the final 30 minutes of the first hypoglycemic episode were 2.3 times higher in subjects who developed HAAF compared with those who did not (P = 0.006).Compared to saline, epinephrine infusion on Day 1 reduced the epinephrine responses by 27% at the 70 and 60 mg/dL glucose steps combined (P = 0.04), with a parallel reduction in hypoglycemic symptoms (P = 0.03) on Day 2. CONCLUSIONS Increases in plasma epinephrine reproduce key features of HAAF in nondiabetic subjects. Marked interindividual variability in epinephrine responses to hypoglycemia may explain an individual's susceptibility to developing HAAF.

Physicians' knowledge regarding epinephrine underuse in anaphylaxis.

Abstract: Background Anaphylaxis is a life-threating hypersensitivity reaction. Epinephrine underuse in patients with anaphylaxis could lead to poor outcomes. There is evidence that the epinephrine use in such patients could be as low as 8%. Objective To assess the percentage of physicians who know that epinephrine is the first-line treatment in anaphylaxis. The secondary objective was to assess knowledge gaps regarding anaphylaxis diagnosis and treatment that could lead to epinephrine underuse. Methods We performed an online survey for physicians in Mexico City, using a 10-item questionnaire assessing anaphylaxis knowledge. We obtained measures of central tendency for statistical analysis, such as frequency, 95% confidence interval, as well as the chi-square test for comparing the groups. Results A total of 196 surveys were considered for analysis. Of all the participants, 96.44% were able to correctly diagnose an anaphylaxis case with cutaneous, respiratory, and cardiovascular symptoms. Fifty-two percent correctly diagnosed anaphylaxis without cutaneous symptoms. The 72.4% of the respondents chose epinephrine as the first-line treatment, 42.3% correctly answered that there is no absolute contraindication to giving epinephrine, and 20.9% ignored whether there was any contraindication for its use. Only 38.3% of participants answered that during discharge they would prescribe an autoinjector. Regarding the administration route, 63.4% answered that the first dose of epinephrine is applied intramuscularly and 50% of the participants chose the correct dose of epinephrine. Only 2.6% of the participants answered all 10 questions correctly. Conclusion There is still some difficulty recognizing anaphylaxis without cutaneous symptoms. Even though two-thirds of physicians identified that epinephrine is the treatment of choice, only 49.5% would have used intramuscular epinephrine as first-line treatment. We found a low percentage of epinephrine ampule prescription and knowledge of the correct dose. These findings can account for epinephrine underuse when dealing with anaphylaxis in the real clinical practice.

Glucose Intolerance on Phaeochromocytoma and Paraganglioma-The Current Understanding and Clinical Perspectives.

Abstract: Half of the patients with phaeochromocytoma have glucose intolerance which could be life-threatening as well as causing postoperative hypoglycemia. Glucose intolerance is due to impaired insulin secretion and/or increased insulin resistance. Impaired insulin secretion is caused by stimulating adrenergic α2 receptors of pancreatic β-cells and increased insulin resistance is caused by stimulating adrenergic α1 and β3 receptors in adipocytes, α1 and β2 receptors of pancreatic α-cells and skeletal muscle. Furthermore, different affinities to respective adrenergic receptors exist between epinephrine and norepinephrine. Clinical studies revealed patients with phaeochromocytoma had impaired insulin secretion as well as increased insulin resistance. Furthermore, excess of epinephrine could affect glucose intolerance mainly by impaired insulin secretion and excess of norepinephrine could affect glucose intolerance mainly by increased insulin resistance. Glucose intolerance on paraganglioma could be caused by increased insulin resistance mainly considering paraganglioma produces more norepinephrine than epinephrine. To conclude, the difference of actions between excess of epinephrine and norepinephrine could lead to improve understanding and management of glucose intolerance on phaeochromocytoma.