Different patterns of mast cell activation by muscle relaxants in human skin

Challenges in Drug and Hymenoptera Venom Hypersensitivity Diagnosis and Management in Mastocytosis

Mastocytosis is a myeloproliferative neoplasm characterized by abnormal proliferation and activation of clonal mast cells typically bearing the KITD816V mutation. Symptoms manifest due to the release of bioactive mediators and the tissue infiltration by neoplastic mast cells. Mast cell activation symptoms include flushing, pruritus, urticaria, abdominal cramping, diarrhea, wheezing, neuropsychiatric symptoms, and anaphylaxis. Up to 50% of patients with mastocytosis report a history of provoked and unprovoked anaphylaxis, with Hymenoptera venom and drugs the most common culprits. NSAIDs, antibiotics, vaccines, perioperative medications, and radiocontrast media are often empirically avoided without evidence of reactions, depriving patients of needed medications and placing them at risk for unfavorable outcomes. The purpose of this review is to highlight the most common agents responsible for adverse drug reactions in patients with mastocytosis, with a review of current epidemiology, diagnosis, and management of drug hypersensitivity and Hymenoptera venom allergy.

Revisiting the role of MRGPRX2 on hypersensitivity reactions to neuromuscular blocking drugs

Anaphylaxis is caused by a variety of triggers including Food and Drug Administration (FDA)-approved antibiotics, contrast media and neuromuscular blocking drugs (NMBDs). Traditionally, drug-induced anaphylaxis was thought to result mainly from IgE-mediated histamine release from mast cells. Recently, a G protein-coupled receptor known as MRGPRX2 has been identified and shown to be highly expressed on human skin but not lung mast cells. The demonstration that many NMBDs induce degranulation in human mast cells via MRGPRX2 led to the idea that this receptor contributes to NMBD-induced hypersensitivity reactions. However, other studies have raised doubts regarding its role in drug-induced hypersensitivity. This review discusses the current status and controversy on MRGPRX2's role on NMBD-induced hypersensitivity.

Severe Bronchoconstriction Caused by Administration of Rocuronium in a 3-Month-Old Infant: Case Report

We present the case of a 3-month-old infant with severe, persistent bronchoconstriction following administration of rocuronium. This observation raises awareness of a rare but potentially life-threatening reaction to neuromuscular blocking agents.

Postanesthetic skin erythema due to succinylcholine versus atracurium

Intraoperative anaphylactic reactions may range from mild, erythema-like to anaphylactic shock, with tension crash and bronchospasm. The substances considered to be most responsible for the occurrence of intraoperative allergic reactions are neuromuscular blocking agents, antibiotics and latex. Recent studies have identified a new receptor, Mas-Related G-Protein-coupled Receptor X2 (MRGPRX2), considered as a target for some neuromuscular blockers such as atracurium, rocuronium or fluoroquinolone, resulting in pseudoallergic or anaphylactoid reactions. Induction of anesthesia can use both depolarizing myorelaxants, useful especially in emergency situations, in the patient with gastric plenitude or at high risk of intubation, and non-depolarizing myorelaxants such as atracurium, cisatracurium and rocuronium. Succinylcholine has a short time of action and it is rapidly metabolized. Atracurium, although having a slightly longer time to action, has the benefit of a low risk of increased levels of potassium in blood, which is extremely important in patients with cardiac pathology or associated kidney diseases. The present study compared the side effects of systemic anesthesia with succinylcholine vs. atracurium.

All-trans-retinoic acid activated mast cells via Mas-related G-protein-coupled receptor-X2 in retinoid dermatitis

BACKGROUND

Retinoic acid (RA)-induced dermatitis is the most frequent side-effect limiting its widespread use. However, the exact mechanisms triggering dermatitis are not fully understood, including the role of skin mast cells. The newly discovered Mas-related G-protein-coupled receptor-X2 (MRGPRX2) in mast cells mediates pseudoallergic drug reactions in several types of dermatitis. A possible contribution of MRGPRX2 to contact dermatitis induced by RA has hitherto not been examined.

OBJECTIVES

To investigate whether all-trans-RA (ATRA) activates mast cells via MRGPRX2/MrgprB2 (the mouse orthologue), contributing to the pathogenesis of retinoid-induced dermatitis.

METHODS

Wild-type (WT) and MrgprB2^-/- mice were treated with topical ATRA to observe local inflammation and mast cell degranulation in vivo by the use of haematoxylin and eosin and immunofluorescence staining. Release of histamine and release of β-hexosaminidase were measured and calcium influx was detected in Laboratory of Allergic Disease 2 (LAD2) cells with specific knockdown targeting MRGPRX2 by small interfering RNA (siRNA) and in primary cells from MrgprB2^-/- mice.

RESULTS

As compared with WT mice, MrgprB2^-/- mice showed resistance to ATRA-triggered contact dermatitis and local inflammatory reactions in the paws. ATRA activated mast cells via the MrgprB2 pathway in murine cells, and via the MRGPRX2 pathway in human mast cells.

CONCLUSIONS

ATRA-induced dermatitis could be achieved by activating mast cells via MRGPRX2/MrgprB2, which may provide a potential therapy target to reduce the side-effect.

Adverse reactions to drugs and biologics in patients with clonal mast cell disorders: A Work Group Report of the Mast Cells Disorder Committee, American Academy of Allergy, Asthma & Immunology

Providers caring for patients with mastocytosis are tasked with the decision to consider therapeutic options. This can come with some trepidation because information available in the public domain lists numerous mast cell (MC) activators based on data that do not discriminate between primates, rodents, and MC lines; do not consider dosage; and do not take into account previous exposure and resultant clinical findings. This being said, there is support in the literature for an enhanced MC response in some patients with mastocytosis and in cases in which there is a greater incidence of adverse reactions associated with certain antigens, such as venoms and drugs. Thus this report provides a comprehensive guide for those providers who must decide on therapeutic options in the management of patients with clonal MC disease.

Focus on the agents most frequently responsible for perioperative anaphylaxis

Adverse reactions (ARs) to drugs administered during general anesthesia may be very severe and life-threatening, with a mortality rate ranging from 3 to 9%. The adverse reactions to drugs may be IgE and non-IgE-mediated. Neuromuscular blocking agents (NMBA) represent the first cause of perioperative reactions during general anesthesia followed by latex, antibiotics, hypnotic agents, opioids, colloids, dyes and antiseptics (chlorhexidine). All these substances (i.e. NMBA, anesthetics, antibiotics, latex devices) may cause severe systemic non-IgE-mediated reactions or fatal anaphylactic events even in the absence of any evident risk factor in the patient's anamnesis. For this reason, in order to minimize perioperative anaphylactic reactions, it is important to have rapid, specific, sensitive in vitro diagnostic tests able to confirm the clinical diagnosis of acute anaphylaxis.

Neuromuscular blockers and reversal agents and their impact on anesthesia practice

Neuromuscular blockers have long been an intricate part of the anesthesia regimen. The scientific progress in pharmacology and physiology has strengthened their clinical relevance, has helped to delineate with precision their medical role, and has enhanced the safety and effectiveness of their use. New frontiers in research will define further the role of these agents in modern anesthesia practice and guide their expanding and discrete clinical applications.

An investigation of the distribution and location of mast cells affected by the stiffness of substrates as a mechanical niche

The distribution and location of mast cells are closely related to their physiological and pathological functions, such as allergic responses, immunity, and fibrosis, and are used in acupuncture. In this study, the distribution of mast cells in vivo was observed, and mechanical clues for understanding their distribution based on mechanical niches were explored. By toluidine blue staining and immunohistochemical staining, we examined the distribution and location of mast cells in rat skin and found that mast cells are distributed in a spatially nonuniform manner, preferring to locate at regions in the tissue and extracellular matrix with stiffness changes. In vitro experiments for studying the distribution of rat basophilic leukemia (RBL-2H3) mast cell line on poly-di-methyl-siloxane (PDMS) substrates with stiffness variations were performed. It was found that RBL-2H3 cells migrate and tend to remain in the areas with stiffness variations. The present research suggests that changing the stiffness of local tissues may stimulate mast cell recruitment, which may be the method by which some traditional Chinese medicine treatments, such as acupuncture. On the basis of the origin of mast cells and our experimental results, we predict that mast cells exist in tissues that contain permeable capillaries and prefer regions with stiffness changes. We discussed this prediction using examples of specific tissues from some cases.

Management around invasive procedures in mastocytosis: An update

OBJECTIVE

Mastocytosis is a chronic hematologic disorder that is characterized by the accumulation of aberrant mast cells and typically involves the skin and/or bone marrow. Patients with mastocytosis are at increased risk of anaphylaxis. Based on theoretical assumptions, medical procedures requiring general anesthesia or radiocontrast media are deemed hazardous for patients with mastocytosis. The objective of this article is to provide a comprehensive overview of the actual risk of iatrogenic anaphylaxis and provide recommendations for daily practice.

DATA SOURCES

Various scientific search engines were used (eg, PubMed and Medline).

STUDY SELECTIONS

Because of the paucity of high-level studies on this topic, all available evidence was considered, including case reports.

RESULTS

Reliable data on the incidence of iatrogenic anaphylaxis in mastocytosis are lacking. However, although the incidence as reported in (retrospective) cohort studies is higher than in the general population, it is still lower than commonly anticipated, with an incidence of 5.4% in 1 study. Adequate premedication and avoidance of certain physical stimuli can further decrease this risk by 10-fold. The role of drugs as elicitors of anaphylaxis is perhaps overestimated, and physical stimuli are at least as important in inducing release of mast cell mediators.

CONCLUSION

This article provides practical recommendations for the management of invasive procedures in patients with mastocytosis based on current knowledge of this topic.

Emerging Roles for MAS-Related G Protein-Coupled Receptor-X2 in Host Defense Peptide, Opioid, and Neuropeptide-Mediated Inflammatory Reactions

Mast cells (MCs) are tissue-resident immune cells that contribute to host defense but are best known for their roles in allergic and inflammatory diseases. In humans, MCs are divided into two subtypes based on the protease content of their secretory granules. Thus, human lung MCs contain only tryptase and are known as MC_T, whereas skin MCs contain both tryptase and chymase and are known as MC_TC. Patients with severe asthma display elevated MCs in the lung, which undergo phenotypic change from MC_T to MC_TC. Although the human genome contains four Mas related G protein coupled receptor X (MRGPRX) genes, an important feature of MC_TC is that they selectively express MRGPRX2. It is activated by antimicrobial host defense peptides such as human β-defensins and the cathelicidin LL-37 and likely contributes to host defense. MRGPRX2 is also a receptor for the neuropeptide substance P, major basic protein, eosinophil peroxidase, opioids, and many FDA-approved cationic drugs. Increased expression of MRGPRX2 or enhanced downstream signaling likely contributes to chronic inflammatory diseases such as rosacea, atopic dermatitis, chronic urticaria, and severe asthma. In this chapter, I will discuss the expression profile and function of MRGPRX1-4 and review the emerging roles of MRGPRX2 on host defense, chronic inflammatory diseases, and drug-induced pseudoallergic reactions. I will also examine the novel aspects of MRGPRX2 signaling in MCs as it related to degranulation and review the mechanisms of its regulation.

Roles of Mas-related G protein-coupled receptor X2 on mast cell-mediated host defense, pseudoallergic drug reactions, and chronic inflammatory diseases

Mast cells (MCs), which are granulated tissue-resident cells of hematopoietic lineage, contribute to vascular homeostasis, innate/adaptive immunity, and wound healing. However, MCs are best known for their roles in allergic and inflammatory diseases, such as anaphylaxis, food allergy, rhinitis, itch, urticaria, atopic dermatitis, and asthma. In addition to the high-affinity IgE receptor (FcεRI), MCs express numerous G protein-coupled receptors (GPCRs), which are the largest group of membrane receptor proteins and the most common targets of drug therapy. Antimicrobial host defense peptides, neuropeptides, major basic protein, eosinophil peroxidase, and many US Food and Drug Administration-approved peptidergic drugs activate human MCs through a novel GPCR known as Mas-related G protein-coupled receptor X2 (MRGPRX2; formerly known as MrgX2). Unique features of MRGPRX2 that distinguish it from other GPCRs include their presence both on the plasma membrane and intracellular sites and their selective expression in MCs. In this article we review the possible roles of MRGPRX2 on host defense, drug-induced anaphylactoid reactions, neurogenic inflammation, pain, itch, and chronic inflammatory diseases, such as urticaria and asthma. We propose that host defense peptides that kill microbes directly and activate MCs through MRGPRX2 could serve as novel GPCR targets to modulate host defense against microbial infection. Furthermore, mAbs or small-molecule inhibitors of MRGPRX2 could be developed for the treatment of MC-dependent allergic and inflammatory disorders.

Anaphylaxis during the perioperative period

The incidence of anaphylaxis during anesthesia has been reported to range from 1 in 4000 to 1 in 25,000. Anaphylaxis during anesthesia can present as cardiovascular collapse, airway obstruction, and/or skin manifestation. It can be difficult to differentiate between immune and nonimmune mast cell-mediated reactions and pharmacologic effects from the variety of medications administered during general anesthesia. In addition, cutaneous manifestations of anaphylaxis are less likely to be apparent when anaphylaxis occurs in this setting. The evaluation of IgE-mediated reactions to medications used during anesthesia can include skin testing to a variety of anesthetic agents. Specifically, thiopental allergy has been documented by skin tests. Neuromuscular blocking agents such as succinylcholine can cause nonimmunologic histamine release, but there have also been reports of IgE-mediated reactions in some patients. Reactions to opioid analgesics are usually caused by direct mast cell mediator release rather than IgE-dependent mechanisms. Antibiotics that are administered perioperatively can cause immunologic or nonimmunologic reactions. Protamine can cause severe systemic reactions through IgE-mediated or nonimmunologic mechanisms. Blood transfusions can elicit a variety of systemic reactions, some of which might be IgE-mediated or mediated through other immunologic mechanisms. The management of anaphylactic reactions that occur during general anesthesia is similar to the management of anaphylaxis in other situations.

Perioperative anaphylactic reactions: Review and procedure protocol in paediatrics

Perioperative anaphylactic reactions are immediate, hypersensitive reactions that are potentially life-threatening resulting from a sudden release of mediators from mast cells and basophiles, due to either immune (IgE or non-IgE mediated) or non-immune mechanisms. The most frequent causing agents are neuromuscular blocking agents (NMBAs), latex and antibiotics, with latex being the first cause in paediatrics. With regard to perioperative anaphylactic reactions, the usual early signs and symptoms of an anaphylactic reaction could be overlooked or erroneously interpreted and non-severe anaphylaxis could go undetected, with a risk of more severe reactions in the future. Using the data registered on the anaesthesia sheet, it is essential to establish a chronological relationship between drugs and/or substances administered and the reaction observed. An elevated level of tryptase confirms an anaphylactic reaction, but this does not usually increase in the absence of compromised circulation. An allergy study should be carried out preferably between 4 and 6 weeks after the reaction, using a combination of specific IgE, skin and controlled exposure tests (if indicated). Test sensitivity is good for NMBAs, latex, antibiotics, chlorhexidine, gelatine and povidone, and poor for barbiturates, opiates (these can give false positives since they are histamine releasers) and benzodiazepines. Special preventive measures should be taken, especially in the case of latex. We present the maximum concentrations recommended for skin tests, the recommended dosage to treat anaphylactic reactions in paediatrics and a procedure algorithm for the allergological study of these reactions.

Identification of a mast-cell-specific receptor crucial for pseudo-allergic drug reactions

Mast cells are primary effectors in allergic reactions, and may have significant roles in diseases by secreting histamine and various inflammatory and immunomodulatory substances^1,2. While classically they are activated by IgE antibodies, a unique property of mast cells is their antibody-independent responsiveness to a range of cationic substances, collectively called basic secretagogues, including inflammatory peptides and drugs associated with allergic-type reactions^1,3. Roles for these substances in pathology have prompted a decades-long search for their receptor(s). Here we report that basic secretagogues activate mouse mast cells in vitro and in vivo through a single receptor, MrgprB2, the orthologue of the human G-protein coupled receptor (GPCR) MrgprX2. Secretagogue-induced histamine release, inflammation, and airway contraction are abolished in MrgprB2 null mutant mice. Further, we show that most classes of FDA-approved peptidergic drugs associated with allergic-type injection-site reactions also activate MrgprB2 and MrgprX2, and that injection-site inflammation is absent in mutant mice. Finally, we determine that MrgprB2 and MrgprX2 are targets of many small molecule drugs associated with systemic pseudo-allergic, or anaphylactoid, reactions; we show that drug-induced symptoms of anaphylactoid responses are significantly reduced in knockout mice, and we identify a common chemical motif in several of these molecules that may help predict side effects of other compounds. These discoveries introduce a mouse model to study mast cell activation by basic secretagogues and identify MrgprX2 as a potential therapeutic target to reduce a subset of drug-induced adverse effects.

Retrodialysis: a review of experimental and clinical applications of reverse microdialysis in the skin

Microdialysis is a method that has been used for decades to recover endogenous mediators, metabolites and drugs from the interstitial space in several tissues of both animals and humans. The principle of microdialysis is the flux of compounds across a semipermeable membrane. The application of microdialysis as a method of drug delivery is a process referred to as retrodialysis, i.e. the introduction of a substance into the extracellular space via a microdialysis probe. Thus, microdialysis also offers opportunities to deliver mediators and drugs to target tissues by adding solutes to the perfusion medium. In this context, retrodialysis combines a method for minimally invasive delivery with a sampling method to study biological processes in health and disease. The aim of this review is to give insight into the use of retrodialysis by outlining examples of retrodialysis studies focusing on applications in skin in animal studies, human experimental investigations and clinical settings.

Anaphylactic and anaphylactoid reactions during the perioperative period

Anaphylactic reactions in the peri-operative period are often serious and potentially life-threatening conditions, involving multiple organ systems in which the clinical manifestations are the consequence of the release of preformed mediators from mast cells and basophils. Anaphylaxis is an immune mediated type I allergic reaction following the massive release of mediators from mast cells and basophils as a response to an allergen. Anaphylactoid reactions are defined as those reactions that produce the same clinical picture with anaphylaxis but are not IgE mediated, occur through a direct nonimmune-mediated release of mediators from mast cells and/or basophils or result from direct complement activation. The occurrence of these reactions during anesthesia, although quite rare, remains a major concern for the anesthesiologists. Thus, the need for systematic screening before surgery and the awareness and expert advice to anaesthesiologists seems to be very critical.

[Mastocytosis. A challenge in anaesthesiology]

Mastocytosis is a general term for a heterogeneous group of rare disorders. Many agents used in anaesthesia can trigger mast cell degranulation with release of histamine, prostaglandin, tryptase and heparin. Therefore, patients with mastocytosis are high-risk patients when undergoing anaesthesia. The management of these patients in anaesthesia will be discussed on the basis of the literature and illustrated with the discussion of three case reports. A premedication with antihistamines and a glucocorticoid is recommended. For induction of general anaesthesia propofol, etomidate, ketamine, a fentanyl-type opioid, cis-atracurium or pancuronium are recommended. Anaesthesia can be maintained either by a total intravenous technique or with a volatile anaesthetic such as sevoflurane.

Antihistamine pretreatment to reduce incidence of withdrawal movement after rocuronium injection

The purpose of this study was to determine the effectiveness of antihistamine therapy for withdrawal movements caused by rocuronium injection. One hundred seventy one ASA I-II adults undergoing elective surgery were randomly assigned to one of two groups. Patients in the control group (Group C) were premedicated with 2 mL normal saline, and those in the antihistamine group (Group A) were pre-medicated with 2 mL (45.5 mg) pheniramine maleate. After the administration of thiopental sodium 5 mg/kg, rocuronium 0.6 mg/kg was injected. Withdrawal movements were assessed using a four-grade scale. The administration of antihistamine reveals lower grade of withdrawal movement after rocuronium injection.

Human mast cells express androgen receptors but treatment with testosterone exerts no influence on IgE-independent mast cell degranulation elicited by neuromuscular blocking agents

Women predominate in the anaphylactic reactions to neuromuscular blocking agents (NMBA). The expression of oestrogen receptors has been demonstrated in mast cells and oestrogen treatment can enhance mast cell degranulation, but the influence of androgens remains largely unclear. Our immunocytochemical study showed the expression of androgen receptor (AR) in mast cells isolated from human foreskin as well as in two human mast cell lines, HMC-1 and LAD2. The amount of AR was most abundant in human skin mast cells as determined by real-time polymerase chain reaction analysis. Treatment of the HMC-1 mast cells with testosterone or 17beta-oestradiol, alone or in combination with different NMBA, did not affect mast cell degranulation as measured by the release of beta-hexosaminidase. Our study shows for the first time the expression of AR in human skin mast cells. Further studies using primary human mast cell cultures are needed to understand whether and how sex hormones can influence mast cell activation.

[Opioid-induced pruritus. Mechanisms and treatment regimens]

Substantial progress has been achieved in recent years in research on the interaction between pain and pruritus. Over and above the known inhibition of pruritus by painful stimuli (e.g. scratching), a foundation for the explanation of opioid-induced pruritus was laid through the discovery of pruritus-specific neuronal processing channels. Although traditionally the degranulating effect of opioids on mast cells was assumed to be the essential mechanism, it is now clear that opioids can also induce itching at the spinal level. Neurons of the dorsal horn of the pain system inhibit spinal itch neurons. If this inhibition is weakened by opioids, the disinhibited itch neurons become active and mediate itching, without stimulation of the primary afferent peripheral nerves. Spinal triggering of itching is observed in particular by activation of mu-opioid receptors (mu-OR), while kappa-OR surprisingly suppress itch. The therapeutic implications of this interaction will be described.

Anesthesia in children with mastocytosis--a case based review

INTRODUCTION

Mastocytosis is a rare heterogeneous disease of bone marrow origin which arises as a consequence of abnormal growth and/or accumulation of clonal mast cells in one or more organs. Sixty-five percent of patients with mastocytosis are children in whom it usually regresses around puberty. Adult patients with mastocytosis have been identified as at high risk of widespread mast cell degranulation in the perioperative period, this finding has not been reported in pediatric patients. This information has been repeated in mastocytosis websites where it has the potential to cause disproportionate alarm in parents.

METHODS

We considered our experience of six children with mastocytosis together with a review of the literature to examine other reports of anesthesia in children with mastocytosis. Our literature search found 57 general anesthetics in 39 children with mastocytosis. In addition, we searched for information about current consensus in diagnosis, classification and treatment of mastocytosis and in vitro and in vivo studies looking at mast cell behavior in response to drugs commonly used during anesthesia.

DISCUSSION

The literature search revealed that general anesthesia has precipitated life threatening complications in adult patients with systemic mastocytosis (SM) but no such complications have been described in children with mastocytosis. Our own experience with children with mastocytosis is of uneventful anesthesia. Advances in the understanding of the genetic basis of mastocytosis suggest that pediatric cutaneous mastocytosis (CM) and SM are different entities. SM in children is extremely rare and is associated with elevated baseline serum tryptase. There are few reports of anesthesia in this group.

CONCLUSION

The risks for most pediatric patients are overstated by mastocytosis websites. Most pediatric patients with CM do not appear to be at risk of widespread mast cell degranulation during anesthesia but because of the small number of cases reported, the risk cannot be ascertained with confidence. Children with SM and a high baseline serum tryptase (marker of mast cell burden) may merit extra precautions but experience in this subgroup is even more limited. Drugs which cause minimal histamine release can be selected from the range of drugs available in most pediatric centers without compromise to technique.

Anaphylaxis during anaesthesia: diagnostic approach

Correct management of anaphylaxis during anaesthesia requires a multidisciplinary approach with prompt recognition and treatment of the acute event by the attending anaesthesiologist, and subsequent determination of the responsible agent(s) with strict avoidance of subsequent administration of all incriminated and/or cross-reacting compounds. However, correct identification of the causative compound(s) and safe alternatives is not always straightforward and, too often, not done. This review is not intended to discuss acute management of anaesthesia-related anaphylaxis but summarizes the major causes of anaphylaxis during anaesthesia and the diagnostic approach of this rare but potentially life-threatening complication. Apart from general principles about the diagnostic approach, history taking and importance of tryptase quantification, more specific confirmatory diagnostic procedures are organized on the basis of the major causes of perioperative anaphylactic reactions.

The Risk of Anaphylactic Reactions to Rocuronium in the United States Is Comparable to That of Vecuronium: An Analysis of Food and Drug Administration Reporting of Adverse Events

Published reports from France and Norway suggest a frequent incidence of anaphylaxis to rocuronium and have raised concerns about its safety. We hypothesized that the Food and Drug Administration Adverse Event Reporting System could be used to confirm whether there has been an unusual incidence of anaphylactic events for rocuronium in the United States (U.S.) and whether the reporting patterns differ within and outside of the U.S.. We queried the Food and Drug Administration Adverse Event Reporting System for 1999 through the first quarter of 2002 for all adverse events for the drugs rocuronium and vecuronium and then searched on the terms considered to represent possible anaphylaxis using proprietary software. We compared the frequency of these terms in data both for rocuronium and vecuronium. We then assessed the occurrence of reports of anaphylaxis-related terms in reports from the U.S. compared with reports originating outside of the U.S.. For rocuronium, the database contained 311 reports, 166 domestic and 145 from foreign sources. Fifty percent of the foreign reports contained an anaphylaxis term versus 20% of the domestic reports (P < 0.001). For vecuronium, the comparable figures were 17% and 19% (not significant) and the total number of reports was 243. The incidence of the reports containing anaphylaxis terms did not differ between vecuronium and rocuronium in the U.S. but were significantly different for foreign reports (P < 0.001). These data confirm that U.S. anesthesia providers have not observed a significant difference in anaphylactic reactions between the two commonly used intermediate-acting muscle relaxants and suggest that frequency of reports of anaphylaxis may be significantly influenced by the area from which the reports originate.

Microdialysis for detection of dynamic changes in tissue histamine levels in experimental thermal injury

Histamine is an important mediator contributing to oedema formation after thermal injury. Tissue histamine concentrations have been previously determined by analyzing tissue biopsies. The microdialysis method enables continuous collection of samples from the extracellular tissue fluid. In this experimental burn study on pigs samples from the extracellular fluid for histamine analysis were collected from superficial, partial thickness and full thickness burn sites during a 24-h period. There was a burn depth-related increase in histamine concentrations during the first 2 h post injury. Deep burns induced a more profound initial increase in tissue histamine concentration than the partial thickness and superficial burns. Histamine concentrations at all burn sites declined until 12 h post injury. There was a second rise in tissue histamine concentrations between 12 and 24 h post injury without a rise in plasma histamine concentrations. Histamine concentrations at all burn sites were higher than at the non-burned control sites. The microdialysis technique is an easily applicable method of collecting on-line samples from burned tissue. This method provides a useful tool in investigating the effects of different treatment modalities on the secretion of substances into interstitial fluid within burned tissue.

Development of ultra short-acting muscle relaxant agents: History, research strategies, and challenges

Author has reviewed the literature and his own work related to the chemistry, pharmacology, and clinical aspects of new muscle relaxants. Emphasis has been placed on the basic science concepts and technologies (e.g. structure-activity relationships, nicotinic receptor pharmacology, and investigation of side effects) behind the development of rapidly and short acting nondepolarizing muscle relaxants.

Is muscle relaxant necessary for cardiac surgery?

The need for continuous and complete paralysis during the entire cardiac surgery has not yet been investigated and is still controversial. In a series of 87 patients undergoing cardiac surgery with normothermic cardiopulmonary bypass, we studied the delay of recovery, incidence of residual paralysis, unwanted patient movement, and difficult surgical conditions after a single dose of atracurium (0.5 mg/kg) or cisatracurium (0.15 mg/kg). Anesthesia was induced with etomidate and remifentanil followed by tracheal intubation. The delay to obtain a train-of-four ratio of >0.9 was longer with cisatracurium than with atracurium (86 +/- 18 versus 97 +/- 19 min). However, at the end of surgery, this ratio was >0.9 for all patients. The presence of unwanted patient movement, diaphragmatic contractions, and difficult surgical conditions were observed. Delay of extubation of the trachea was similar in both groups. We conclude that there is no need for continuous neuromuscular blockade during cardiac surgery. A single dose of either atracurium or cisatracurium is sufficient to provide efficient paralysis from the start of induction leading to quicker recovery from paralysis in fast-track cardiac surgery.

Adverse reactions to neuromuscular blocking agents

Neuromuscular blocking agents (NMBAs) play a predominant role in the incidence of severe adverse reactions occurring during anesthesia. Most hypersensitivity reactions are of immunologic origin (IgE-mediated) or are related to direct stimulation of histamine release. The incidence of IgE-mediated hypersensitivity or anaphylaxis is estimated between 1 in 10,000 and 1 in 20,000 anesthesias, and NMBAs represent the most frequently involved substances, with a range of 50% to 70%. Any suspected anaphylactic reaction must be extensively investigated using combined perioperative and postoperative testing. Because of the frequent cross-reactivity observed with muscle relaxants, every available NMBA should be tested. This should help provide documented advice for future administration of anesthesia. There is no demonstrated evidence for systematic preoperative screening in the general population at this time. Other well-known adverse effects have been described, such as the succinylcholine-triggered cytotoxic effects on muscle cells, but these are responsible for characteristic clinical symptoms, which are usually easy to distinguish from anaphylactic reactions

Opioid-induced mast cell activation and vascular responses is not mediated by mu-opioid receptors: an in vivo microdialysis study in human skin

Activation of mast cells and the systemic release of histamine is a common side effect of opioids. Nevertheless, fentanyl and its derivatives show only a slight activation of mast cells with a subsequent liberation of histamine and tryptase. In this study, we used intradermal microdialysis to assess whether this stimulatory effect of opioids on mast cells depends on the activation of opioid receptors. This new approach allowed us to measure the dose-dependent release of histamine and tryptase from mast cells and the subsequent vascular and sensory effect without systemic side effects in volunteers. The opiate codeine and the synthetic opioids meperidine, fentanyl, alfentanil, sufentanil, remifentanil, buprenorphine, and the opioid antagonist naloxone were tested. Only codeine and meperidine induced mast cell activation with the release of tryptase and histamine, leading to protein extravasation, flare reactions, and itch sensations. Because naloxone did not attenuate these effects, it is unlikely that mu-opioid receptors are involved in the activation of mast cells.

IMPLICATIONS

Opioid effects on mast cells were assessed using intradermal microdialysis. Mast cell activation was seen with codeine and meperidine; no other opioid induced degranulation. Therefore, histamine release seen at large concentrations of potent micro agonists is caused by an unspecific effect rather than an activation of opioid receptors.

Anaphylaxis during the perioperative period

Anesthesiologists use a myriad of drugs during the provision of an anesthetic. Many of these drugs have side effects that are dose related, and some lead to severe immune-mediated adverse reactions. Anaphylaxis is the most severe immune-mediated reaction; it generally occurs on reexposure to a specific antigen and requires the release of proinflammatory mediators. Anaphylactoid reactions occur through a direct non-immunoglobulin E-mediated release of mediators from mast cells or from complement activation. Muscle relaxants and latex account for most cases of anaphylaxis during the perioperative period. Symptoms may include all organ systems and present with bronchospasm and cardiovascular collapse in the most severe cases. Management of anaphylaxis includes discontinuation of the presumptive drug (or latex) and anesthetic, aggressive pulmonary and cardiovascular support, and epinephrine. Although a serum tryptase confirms the diagnosis of an anaphylactic reaction, the offending drug can be identified by skin-prick, intradermal testing, or serologic testing. Prevention of recurrences is critical to avoid mortality and morbidity.

Mivacurium and bronchospasm

IMPLICATIONS

Because of case reports of severe bronchospasm after the use of mivacurium, we used the Food and Drug Administration MedWatch database to determine the frequency of bronchospasm as an adverse event after the use of nondepolarizing muscle relaxants.

Factors determining the duration of tracheal intubation in cardiac surgery: a single-centre sequential patient audit

BACKGROUND AND OBJECTIVE

The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.

METHODS

Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.

RESULTS

In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.

CONCLUSIONS

In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings

BACKGROUND AND OBJECTIVE

Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction.

METHODS

Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH.

RESULTS

In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant).

CONCLUSIONS

The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Anaesthetic strategies to reduce perioperative blood loss in paediatric surgery

In adults, a number of measures to reduce perioperative blood loss have been established. These techniques serve to reduce patients' exposure to homologous blood. Most adults are concerned with this issue especially since many patients became infected with human immunodeficiency virus (HIV) during the 1980s through exposure to blood components. While blood-saving strategies are widely used in adults, they are mostly neglected in infants. However, it is these young patients with their whole life in front of them who, it could be argued, would benefit especially from any potentially avoidable infection (HIV, hepatitis, etc.) or immunological complications. In infants and small children, these blood-sparing techniques may not be as effective as in adults and technical limitations may prevent their application. However, some of these measures can be used and may serve to prevent or reduce exposure to homologous blood. In the following review, blood-saving techniques established in adults are described and their applicability for paediatric patients discussed.