Clinician Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Clinician and links to relevant pages within the course.
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| Review 2 Citron DM. Appelbaum PC.:
How far should a clinical laboratory go in identifying anaerobic isolates, and who should pay?
Clinical Infectious Diseases. 16 Suppl 4:S435-8, 1993Identification of anaerobic bacteria in specimens from sites of infection due to mixed organisms can be time-consuming and expensive. Laboratories should limit anaerobic workups by testing only those specimens that have been properly collected and transported to the laboratory.Use of selective and differential media for initial processing can provide rapid and relevant information to the clinician. Anaerobes isolated from normally sterile sites and sites of serious infection should always be completely identified. Group-or genus-level identifications may suffice in other instances.The Bacteroides fragilis group of organisms should always be identified because of their virulence and resistance to many antimicrobial agents.Some of the other organisms that warrant identification include Clostridium septicum (associated with gastrointestinal malignancy); Clostridium ramosum, Clostridium innocuum, and Clostridium clostridioforme (which are resistant to antibiotics); Clostridium perfringens (a cause of myonecrosis and gas gangrene,potentially serious infection); anaerobic cocci (which may be resistant to metronidazole and clindamycin); and fusobacteria (which may be virulent and resistant to clindamycin and penicillin). | View Page |
| Which of the following statements about anticoagulant therapy is false? | View Page |
| Laboratory Tests of Hemostatic Function – Prothrombin Time The INR component of the laboratory result is a calculated value that is used by the clinician to monitor anticoagulant therapy and adjust dosage as dictated by clinical status. An INR of 2.0 - 3.0 is often desired as the therapeutic range. The following formula is used by the clinical laboratory to derive an INR value. The INR must be adjusted for every new lot of PT reagent. INR= (PT of patient/PT of geometric mean of the normal population)ISI The International Sensitivity Index, or ISI value, is provided by the reagent manufacturer as the relative sensitivity of the reagent itself. The INR is used to standardize PT results, and in turn, anticoagulant therapy, across laboratory instrumentation, methodologies, and locale. Be sure to frequently check that ISI values match those of the lot currently in use as erroneous results may otherwise occur . | View Page |
| Laboratory Tests of Hemostatic Function - APTT The activated partial thromboplastin time (APTT) is a screening test that helps to assess the functionality of both the intrinsic and common pathways. The effectiveness and presence of all the coagulation factors are assayed by this diagnostic test with the exception of factors VII and XIII. The results of the activated partial thromboplastin time are used in conjunction with other diagnostic tests, as well as the clinical picture of the patient, to determine hemostatic abnormalities which may be present. In addition to being an integral part of the coagulation disorder assessment process, the APTT is used to determine therapeutic effectiveness of heparin administration. Activated partial thromboplastin time results are presented to the clinician in seconds- the actual time elapsed until a clot was detected using the laboratory's instrument/reagent system. | View Page |
| Fibrin/Fibrinogen Degradation Products and D-dimers The presence of D-dimers in plasma or whole blood indicates that fibrin has been formed and degraded (fibrinolysis). Plasmin can also degrade intact fibrinogen, generating fibrinogen degradation products that are detected in fibrin/fibrinogen degradation products (FDP) assays. D-dimers and FDP can become elevated whenever the coagulation and fibrinolytic systems are activated. The presence of D-dimer confirms that both thrombin and plasmin have been generated since it can only be produced as the result of the plasmin degradation of fibrin. This makes the test for D-dimers more specific for fibrinolysis than the FDP test that also detects the products of the direct proteolysis of fibrinogen (fibrinogenolysis).The D-dimer test can be useful in the diagnosis of deep venous thrombosis (DVT) or pulmonary embolism (PE), two forms of venous thromboembolism (VTE). When the test is being used for this purpose, it is important that D-dimer levels are accurately measured and accurately reported because of the serious nature of this clinical decision. If the test is positive in a patient suspected to have DVT or PE, clinicians proceed with further diagnostic tests. If the test is negative, depending on the clinical situation and the sensitivity of the D-dimer assay, DVT or PE is considered unlikely and further diagnostic tests for DVT or PE might not be pursued. D-dimer is a sensitive, but not specific, diagnostic test for disseminated intravascular coagulation, and an indicator of increased risk of future myocardial infarction in patients evaluated for chest pain. | View Page |
| Additional Variables To ensure reliability of results, many other factors besides controls are monitored. These include: water quality analytic balance calibration glassware calibration centrifuge calibration thermometer calibration electric power stability heating bath temperatures refrigerator temperatures freezer temperatures expiration of reagents, standards, and controls instrument maintenance procedure manuals, including written step-by-step procedures of all tests performed by laboratory method selection, based on local population and clinician needs normal range verification based on the local population technical competencies of laboratory staff members | View Page |
| Steady State Most drugs are not given as a single dose but are part of a regimen. It is the physician's responsibility to prescribe a drug so that the concentration of that drug reaches a safe and effective level. The dosing-goal for the prescribing clinician, if multiple doses of a drug will be given, is for both the peak and the trough drug levels to be consistently within the therapeutic range. If a drug is given at intervals that are the same as its half-life, it will take about 5 half-lives to reach steady state. | View Page |
| Sampling Ideally, a drug level would be monitored frequently and consistently, providing the clinician with a detailed pharmacokinetic profile over time. In reality, serum samples are often measured only during relatively infrequent clinic visits, meaning that many days or weeks may pass before a drug concentration 'snap-shot' is taken. | View Page |
| Reticulocyte identification Reticulocytes are red blood cells prematurely released from the bone marrow. On a Wright-Giemsa stained blood smear, they appear as polychromatic macrocytes. Their presence in the peripheral blood may suggest hemolysis or bleeding. Their presence is expressed as a percentage of the red cell count: newly born= 3-7%; up to one week of age=1-3%; >one week =0.3-1.8%. Automated or manual methods may be used to enumerate reticulocytes. In clinical context, retics must be separated from debris, precipated stain, Pappenheimer bodies, Howell-Jolly bodies, and Heinz bodies. | View Page |
| Warm antibody hemolytic disease A 49-year-old male with pneumonia was treated with penicillin. He became jaundiced with yellow sclera. Observe the photograph of his peripheral blood smear. Anisocytosis was observed with pale-centered microcytes and polychromatophilic macrocytes. Since penicillin is a classic offender for autoimmune hemolytic disease, the clinician asked for an antihuman globulin (AHG) test, also known as the Coombs test. A positive AHG reaction occurs when the antibody stimulated by penicillin becomes attached to red blood cells. Hemolysis follows, leaving the patient with jaundice and a peripheral blood smear, as demonstrated in the photograph. | View Page |
| Ways out of the dilemma What clear courses of action might the clinician take if the technologist reports out from this smear 3+ acanthocytes, 1+ target cells and occasional helmet cells? Gleaning information from the review of peripheral blood smears is important for the technologist, physician, and surely for the patient. Extreme pressures of time constraints and shifting dynamics in communication, from face-to-face encounters to dependency on technology, make innovative solutions to physician-patient information dilemmas imperative. Reporting systems often are geared more toward retrievability, suiting the needs of administrators and record keepers rather than being clearly directed toward improving patient care outcomes. A prime solution to this communication dilemma is to provide technologists with written descriptions and images of specific abnormal findings from peripheral blood smears. With a high degree of probability, these may link directly with underlying information connected to diseases. Mutually understood terms must be established to convert subjective qualitative peripheral blood smear findings into mutually understandable information. For example, regarding the smear shown, it was learned that the patient had recently undergone splenectomy. Creating an integrated communication system for information sharing (providing essential patient information by telephone follow-up or use of a system for e-mail feedback) can help ensure a favorable clinical outcome. | View Page |
| Reporting of laboratory data in regard to blood cell abnormalities Laboratory data must be presented to clinicians in a user friendly way to promote effective decision making. Databases must be designed to provide clear information that leads quickly to the best patient care outcome. We continue learning how to collect and retrieve laboratory data from our machines, but we are not always in tune to how entry and retrieval of data is geared to and, more directly, influences patient care outcomes. Examples of blood cell abnormalities on a peripheral blood smear that may immediately direct the physician to a specific diagnosis are: (1) presence of target cells as found in thalassemia or hemoglobinopathies and target cells in liver disease, particularly with obstructive jaundice; (2) burr cells as a signal of chronic renal disease and uremia; and (3)atypical neutrophil inclusions relating to genetic disorders. Critical appraisal of such observations could add valuable clues for a diagnosis. Laboratory professionals must establish a set of principles for orderly observation of blood cell morphology, have a clear vision of the applications of their work, and understand the potential clinical implications of their reports and interpretations. Emphasis on values and relevance focuses on patient care outcomes and their dependency on prompt availability of results and contextual interpretations. | View Page |
| Qualitative reports: Follow-up Any review of a peripheral smear is highly subjective; therefore, each laboratory must establish its own guidelines for quantitating observations and issuing reports in a consistent format. The key question for the laboratory is "How will the clinician use the terms of qualitative results in the reports issued to decide on the next course of action with this patient?" Formats for reporting have been geared more toward the needs of instrumentation facilitation and computer management than toward needs of access and understanding by clinicians working to improve patient care outcomes. Evidence based medicine (EBM) is the formal term used for the process by which research evidence, collective clinical experience, and the user friendly rendering of testing results are integrated to evaluate patient care outcomes. | View Page |
| Poikilocytosis Poikilocytosis is a general term used to describe variations in shape. Practically, however, this term has little meaning since cells varying in shape must be specifically identified to be of diagnostic value to the clinician.The work of the French hematologist, Marcel Bessis, with the scanning electron microscope has significantly increased our understanding of the various unusual shapes erythrocytes may assume and their associated pathophysiology. | View Page |
| Fructose Fructose makes up 99% of the reducing sugar present in semen. This sugar is produced in the seminal vesicles and its absence may indicate an obstruction proximal to these glands.
Although a fructose test is NOT part of a routine semen analysis, the clinician may want to measure this in cases of azoospermia. In azoospermia secondary to obstruction of the ejaculatory ducts or absence of the vas deferens, fructose is usually absent. When azoospermia is caused by failure of the testes to produce sperm, fructose is present. Measuring fructose levels can thus help the clinician determine the cause of azoospermia, although measurement of pH is often more useful in this regard.
The procedure for determining the amount of fructose in semen involves heating semen in a strong acid in the presence of resorcinol. Fructose gives a red color to this solution when present. | View Page |
| pH The pH of normal fresh semen is 7.0 or greater. Acid conditions can lead to reduced sperm motility and viability.Secretions of the different glands of the male reproductive tract contain fluids of different pH. The portion of semen that originates in the seminal vesicles is basic, that of the prostate gland is acidic. If the pH is low it could mean that there is an obstruction in the ejaculatory duct below the level of the seminal vesicles or it could signal absence of the vas deferens. Low pH is often associated with low volume since both basic pH and much of semen volume are products of the seminal vesicles. Measuring pH can thus help a clinician determine the cause of azoospermia (absence of sperm in semen).The pH is measured using pH testing strips. A drop of semen is placed on a pH strip and allowed to develop full color. Final color is compared to a standard. For the most accurate results, use test strips with a sensitivity in the basic range, for example from 6.0 to 10.0. | View Page |
| Summary of macroscopic evaluation In summary, the macroscopic examination of semen can provide important information. Changes in semen liquefaction parameters, viscosity, volume, pH may provide clues to the clinician about causes of infertility or abnormalities of the reproductive tract. | View Page |
| Assume that several other lymphocytes similar to the one in the center of the photograph are found on review of the peripheral smear. A work up for leukemia should be recommended. | View Page |
| An electronic platelet count of 40,000/cumm was reported. Review of the peripheral blood smear(see photograph)reveals single platelets in open fields and platelet clumps. The platelet count is likely incorrect. | View Page |
| Additional comments on this exercise The following pages in this presentation includes a series of white blood cell abnormalities that may be identified in a peripheral blood smear. Many of the cases will simulate the practice of a peripheral smear review by a hematology morphologist. He/she must asses what responses in patient care may be triggered by the clinician attempting to interpret the reported findings on a peripheral smearObservations of white blood cell abnormalities in the peripheral blood smear should be reported so as to direct the physician to an immediate specific diagnosis, such as: (1) atypical lymphocytes suggesting infectious mononucleosis rather than leukemia, (2) toxic granules in neutrophils as in acute infections, or atypical granules suggesting a genetic disorder, (3) an unusual mix of cells, such as too many or too few neutrophils, monocytes, or other myeloid cells, and (4) the presence of giant platelets, myelocytes, or other cells suggesting a myelodysplastic syndrome.In summary, laboratory data should be presented to clinicians in a user friendly way to promote effective decision making. The design of the data base of information must be directed toward providing clinically helpful information clearly and quickly in order to facilitate appropriate action in terms of optimizing patient care outcomes.d | View Page |