Anaphylaxis.

The syndrome of anaphylaxis is a life-threatening event in which the potential for patient morbidity and mortality is high. An understanding of the pathophysiology of anaphylaxis, the most serious of the allergic disorders, is paramount for its diagnosis. In addition to these elements, this article discusses newly recognized causes of anaphylaxis and reviews its treatment.     

Anaphylaxis.

Anaphylaxis is a severe systemic allergic reaction that can involve multiple systems of the body. Anaphylaxis often is unpredictable, can have a rapid onset, and, if serious enough, can have life-threatening consequences. If an anaphylactic reaction is the result of an antigen antibody response, it is considered anaphylaxis. If the reaction is caused by a nonantibody trigger, it is considered anaphylactoid. Clinically, however, both responses appear the same and require the same management and treatment. With the development of new protein drugs and their use as therapeutic agents, the risk of anaphylaxis will most likely increase. For this reason, the infusion nurse specialist needs to have the knowledge and skills necessary to recognize and respond appropriately when anaphylaxis occurs. This article discusses the history, definition, incidence, risk factors, etiology, pathophysiology, and clinical findings of anaphylaxis. Appropriate prevention, management, and treatment also are discussed, with special attention given to medication-related anaphylaxis.     

Anaphylaxis. A preventable emergency

Anaphylaxis is a life-threatening reaction that may be caused by a variety of agents. Diagnosis depends on the presence of a constellation of symptoms (eg, laryngeal edema, bronchospasm, hypotension, urticaria). The goal of therapy is maintenance of an effective airway, respiratory function, and circulation. Subcutaneous epinephrine, H1 and H2 antihistamines, and a prolonged period of observation (at least 8 hours) should be used in all patients. After the acute attack has been managed, a thorough investigation of possible causes should be made and the patient referred to a specialist, if indicated. Desensitization therapy, premedication before high-risk exposures, and careful avoidance of known causative agents are effective preventive measures. Direction in self-administration of epinephrine is critical in these patients and may prove lifesaving.     

Phenotypic characteristics of Enterococcus faecium variants confirmed by intergenic ribosomal polymerase chain reaction and E. faecium polymerase chain reaction.

Enterococcus faecium has recently emerged as a serious nosocomial pathogen. The emergence of multiple antimicrobial agent-resistant E. faecium has been remarkable; with its strains it is one of the most phenotypically heterogeneous of all enterococcal species. About 15% of enterococcal strains isolated from human clinical specimens were found to have atypical biochemical characteristics. In order to determine if these strains were E. faecium variants, intergenic ribosomal polymerase chain reaction (ITS-PCR) and E. faecium PCR (EfPCR) were performed in 45 atypical strains, and the two PCR results were used to analyze phenotypic characteristics of the strains. As many as 60% (27/45) of the atypical strains were identified as E. faecium. Thus, it is concluded that if an enterococcal strain shows positive reaction to arabinose, arginine, and ribose and negative reaction to methyl-alpha-D-glucopyranoside and pigment, it should be identified as E. faecium.     

Solid-Phase polymerase chain reaction

The polymerase chain reaction (PCR) has facilitated the diagnosis of infectious diseases and genetic disorders, because of its ability to amplify minute amounts of nucleic acids. To distinguish genes of interest from nonspecifically amplified DNA, PCR products commonly are fractionated by electrophoresis, transferred to membranes, and then probed with a labeled internal sequence-specific oligonucleotide. Alternatively, the PCR products have been labeled directly, and hybridized to immobilized oligonucleotide probes. These methods require the tedious physical transfer of the PCR products. In order to amplify and immobilize genes simultaneously, we have developed a simple solid-phase PCR method. The technique enabled us to detect the HIV envelope gene readily without any transfer of amplified DNA. © 1994 Wiley-Liss, Inc.     

Rapid electrochemiluminescence assays of polymerase chain reaction products.

We demonstrate the first use of an electrochemiluminescent (ECL) label, [4-(N-succimidyloxycarbonylpropyl)-4'-methyl-2,2'- bipyridine]ruthenium(II) dihexafluorophosphate (Origen label; IGEN Inc.), in DNA probe assays. This label allows rapid (less than 25 min) quantification and detection of polymerase chain reaction (PCR)-amplified products from oncogenes, viruses, and cloned genes. For the PCR, we used labeled oligonucleotide primers complementary to human papiloma virus and the Ha-ras oncogene. These samples were followed by ECL analysis or hybridization with specific, Origen-labeled oligonucleotide probes. These studies demonstrate the speed, specificity, and effectiveness of the new ECL labels, compared with 32P, for nucleic acid probe applications. We describe formats involving conventional methodologies and a new format that requires no wash step, allowing simple and rapid sample analysis. These rapid assays also reduce PCR contamination, by requiring less sample handling. Improvements in ECL detectability are currently under investigation for use in DNA probe assays without amplification.     

Anaphylaxis

The clinical syndrome of anaphylactic shock is a disorder produced by multiple mechanisms and pharmacological and environmental factors. The syndrome may be produced by both immunologic and nonimmunologic mechanisms and is due to the release of preformed biologically active mediators and the generation of biologically active mediators. The main mediator appears to be histamine. Although there are a number of defined predisposing factors, the majority of first reactions appear unpredictably. The mainstay of treatment is the use of epinephrine, volume replacement, and positive pressure ventilation. The follow-up and documentation of details of the reaction and exhaustive efforts to determine the precipitating factor are important aspects of the subsequent safety of the patient. History may be of more value than diagnostic testing. The use of H1 and H2 blockers, with steroids and sympathomimetics, may reduce the risk or magnitude of reactions in patients with a past history of a reaction.