Critical reviews in clinical laboratory sciences
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Crit Rev Clin Lab Sci · Jul 2011
ReviewMethadone: a review of drug-drug and pathophysiological interactions.
Numerous established and potential drug interactions with methadone are clinically important in people treated with methadone either for addiction or for chronic pain. Methadone users often have comorbidities and are prescribed drugs that may interact with methadone. Methadone is extensively metabolized by cytochrome P450 (CYP) 3A4 and to a lesser extent by CYP 1A2, 2D6, 2D8, 2C9/2C8, 2C19, and 2B6. ⋯ Interactions of methadone with other drugs can lead to increased or decreased methadone drug levels in patients and result in potential overdose or withdrawal, respectively. The former can contribute to methadone's fatality. Prescribers of methadone and pharmacists should enquire about any new medications (including natural products and over-the-counter medications) periodically, and especially when an otherwise stable patient suddenly experiences drug craving, withdrawal or intoxication.
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Crit Rev Clin Lab Sci · May 2011
ReviewHemolyzed specimens: a major challenge for emergency departments and clinical laboratories.
The term hemolysis designates the pathological process of breakdown of red blood cells in blood, which is typically accompanied by varying degrees of red tinge in serum or plasma once the whole blood specimen has been centrifuged. Hemolyzed specimens are a rather frequent occurrence in laboratory practice, and the rate of hemolysis is remarkably higher in specimens obtained in the Emergency Department (ED) as compared with other wards or outpatient phlebotomy services. Although hemolyzed specimens may reflect the presence of hemolytic anemia, in most cases they are due to preanalytical sources related to incorrect procedures or failure to follow procedures for collection, handling and storage of the samples; some of these are typical of the ED. Since hemolyzed specimens are often an important cause of relationship, economic, organizational and clinical problems between the ED and the clinical laboratory, it is essential to develop effective processes for systematically identifying unsuitable specimens (e.g. by using the hemolysis index), differentiating in vitro from in vivo hemolysis, troubleshooting the potential causes, and maintaining good relations between the clinical laboratory and the ED.
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There have been numerous publications on the coagulopathy of cardiopulmonary bypass (CPB). This review provides an introduction to the history and main components of current CPB circuits and summarizes the current knowledge of pathogenesis, prevention, and treatment of the CPB coagulopathy. It encompasses an overview of intra- and postoperative monitoring of coagulation with special emphasis on the near-patient testing, its main complications, and the transfusion support, while taking into account the major changes in the technology used and supportive care provided since its inception.
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Hypersensitivity pneumonitis (HP) is a group of immunologically mediated lung diseases caused by the inhalation of environmental agents in susceptible individuals. Most HP patients are non-smokers and have been exposed to organic dusts from vegetable or animal products. Some HP cases are associated with exposures to relatively simple chemical compounds. ⋯ Pulmonary fibrosis and physiological abnormalities occurring in chronic HP may be irreversible. Steroid therapy is helpful for symptomatic relief, but probably does not affect the long-term prognosis. Type III and type IV hypersensitivity reactions are involved in the pathogenesis; alveolar macrophages and T cells (Th-1 type) play a central role in the immune responses after antigen exposure via their increased interaction and secretion of regulatory mediators.
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Metabolic alkalosis is the commonest form of acid-base disorder seen in critically ill patients. Although the effects of acidosis have long been known, those of severe metabolic alkalosis are only slowly being recognized. Metabolic alkalosis is itself associated with an increased mortality and a knowledge of the causative factors and treatment options is important. ⋯ Metabolic alkalosis leads to hypoventilation in patients both with and without lung disease, although in the latter, the effect is relatively transient. In patients with chronic obstructive lung disease, however, the development of metabolic alkalosis leads to prolonged hypoventilation and the establishment of a mixed acid-base disorder that may cause difficulty in weaning in the ventilated patient. This is an often forgotten cause of prolonged stay in the intensive care unit with consequent cost and morbidity implications.