Heparin test

POC assays can be done quickly. Another advantage is that they can be performed on very small amounts of blood (2-3 drops of blood collected from a finger pulp), serum, or a blood sample taken earlier for EDTA or heparin tests. 

The tests carried out for the evaluation of the blood anticoagulant activity of sulfated N-carboxymethyl chitosan are the same as those for the determination of heparin, i.e. the antithrombin test for the thrombin inhibition and the heparin test for the factor Xa inhibition. Both of these tests were done by spectrophotometry at 405 nm on the p-nitroaniline liberated from a chromo-genic substrate. 

The problems in explaining the basic pathogenetic mechanism are well demonstrated by an observation of Fredrickson et al. (1963). In one family with fat-inducible hyperlipemia these authors found an affected girl who in the heparin test showed the expected markedly diminished lipolytic activity, and an equally... 

Before administering the first dose of heparin, the nurse obtains the patients vital signs. The most commonly used test to monitor heparin is activated partial thromboplastin time (APTT). Blood is drawn for laboratory studies before giving the first dose of heparin to obtain baseline data (See the discussion on preadministration assessment for the oral anticoagulants.)... 

Periodic platelet counts, hematocrit, and tests for occult blood in die stool should be performed throughout die entire course of heparin therapy. 

Blood coagulation tests are usually ordered before and during heparin tiierapy, and die dose of heparin is adjusted to die test results. Optimal results of therapy are obtained when the APTT is 1.5 to 2.5 times the control value The LMWHs do not require close monitoring of blood coagulation tests. 

Each time heparin is given, die nurse inspects the needle site for signs of inflammation, pain, and tenderness along die padiway of die vein. If these should occur, die use of diis site is discontinued and a new intermittent set is inserted at a different site Coagulation tests are usually performed 30 minutes before die scheduled dose and from die extremity opposite die infusion site... 

Blood coagulation tests for those receiving heparin by continuous IV infusion are taken at periodic intervals (usually every 4 hours) determined by the primary health care provider. If the patient is receiving long-term heparin therapy, blood coagulation tests may be performed at less frequent intervals... 

If administration of this drug is necessary, the nurse monitors the patient s blood pressure and pulse rate every 15 to 30 minutes for 2 hours or more after administration of the heparin antagonist. The nurse immediately reports to the primary health care provider any sudden decrease in blood pressure or increase in the pulse rate The nurse observes the patient for new evidence of bleeding until blood coagulation tests are within normal limits. To replace blood loss, the primary health care provider may order blood transfusions or fresh frozen plasma... 

Discuss the use of laboratory tests in monitoring heparin administration. 

Heparin and warfarin are widely used in the treatment of thrombotic and thromboembolic conditions, such as deep vein thrombosis and pulmonary embolus. Heparin is administered first, because of its prompt onset of action, whereas warfarin takes several days to reach full effect. Their effects are closely monitored by use of appropriate tests of coagulation (see below) because of the risk of producing hemorrhage. 

A number of laboratory tests are available to measure the phases of hemostasis described above. The tests include platelet count, bleeding time, activated partial thromboplastin time (aPTT or PTT), prothrombin time (PT), thrombin time (TT), concentration of fibrinogen, fibrin clot stabifity, and measurement of fibrin degradation products. The platelet count quantitates the number of platelets, and the bleeding time is an overall test of platelet function. aPTT is a measure of the intrinsic pathway and PT of the extrinsic pathway. PT is used to measure the effectiveness of oral anticoagulants such as warfarin, and aPTT is used to monitor heparin therapy. The reader is referred to a textbook of hematology for a discussion of these tests. 

Sample Collection and Enzyme Stability. Serum samples are collected with chemically clean, sterile glassware. Blood is allowed to clot at room temperature, the clot is gently separated from the test tube with an applicator stick, and the blood is centrifuged for 10 minutes at 1,000 g. If the red cells are known to contain the enzymes whose activity is being measured, as in the case of LD, even slightly hemolyzed serums must be discarded. When acid phosphatase is to be measured, the serum should be placed immediately in ice and processed as soon as possible, or it should be acidified by the addition of a small amount of sodium citrate. Anticoagulants such as EDTA, fluoride and oxalate inhibit some serum enzymes. However, heparin activates serum lipoprotein lipase. 

Give protamine sulfate 1 mg/100 U heparin received in last 3 hours (give initial 10 mg test dose by slow IVP over 10 minutes and observe for anaphylaxis if stable give entire calculated dose by slow IVP maximum dose 100 mg)... 

The concept that different structural domains on the heparin chains are principally involved for optimal activity in the foregoing interactions could not be perceived in early work on structure-activity correlations, because the activity of heparin has been most frequently evaluated only with whole-blood-clotting tests (such as the U.S.P. assay). Development of assays for specific clotting-factors (especially Factor Xa and thrombin) has permitted a better insight into the mechanism of action of heparin at different levels of the coagulation cascade. 

Connaghan D. G Francis C. E., Ryan D. H., Marder V. J. Prevalence and clinical implications of heparin-associated false positive tests for serum fibrin(ogen) degradation products. Am J Clin Pathol 1986 86,304-10. 

The LiClprecipitation is necessary to remove any residual heparin, which may intefere with the labeling reaction. Some vendors (e.g., Ambion and Qiagen) sell RNA purification columns that should remove heparin. We have not tested any of these yet. 

In practice, some anticoagulation agents such as heparin or antiplatelet agents, e.g. nitric oxide (NO) are delivered to sensor sites in order to reduce the risk of thrombus formation. Nitric oxide (NO), which is a potent inhibitor of platelet adhesion and activation as well as a promoter of wound healing in tissue, has been incorporated in various polymer metrics including PVC (poly(vinyl-chloride)), PDMS (poly-dimethyl-siloxane) and PU (poly-urethanes). Those NO release polymers have been tested in animals as outer protection coatings and have shown promising effects for the analytical response characteristics of the sensor devices [137],... 

Heparinized blood samples may be stored at 4°C for up to 48 h without affecting the SCE response (Lambert et al., 1982). If the test agent is known to react with serum or red blood cells, the mononuclear lymphocytes may be isolated by use of a Ficoll/Hypaque gradient (Boyum, 1968). 

Test System Human blood. Collect 30 ml heparinized blood for whole blood and plasma (three tubes) and 30 ml clotted blood for serum (two tubes) from each of six donors. 

HR 76, BP 110/60 Lay down for vital signs. Unable to perform on tests, but did write some words when asked to Draw-a-Man. 10 cc of blood drawn (3 heparinized, 7 clotted). 

The results obtained with ISEs have been compared several times with those of other methods. When the determination of calcium using the Orion SS-20 analyser was tested, it was found that the results in heparinized whole blood and serum were sufficiently precise and subject to negligible interference from K and Mg ([82]), but that it is necessary to correct for the sodium error, as the ionic strength is adjusted with a sodium salt [82], and that a systematic error appears in the presence of colloids and cells due to complexa-tion and variations in the liquid-junction potential [76]. Determination of sodium and potassium with ISEs is comparable with flame photometric estimation [39, 113, 116] or is even more precise [165], but the values obtained with ISEs in serum are somewhat higher than those from flame photometry and most others methods [3, 25, 27, 113, 116]. This phenomenon is called pseudohyponatremia. It is caused by the fact that the samples are not diluted in ISE measurement, whereas in other methods dilution occurs before and during the measurement. On dilution, part of the water in serum is replaced by lipids and partially soluble serum proteins in samples with abnormally increased level of lipids and/or proteins. 

Drug/Lab test interactions Asympiomai c reversible increases in AST and ALT aminotransferase levels have occurred in patients treated with LMWHs and heparin. Because aminotransferase determinations are important in the differential diagnosis of Ml, liver disease, and PE, interpret elevations that might be caused by LMWHs with caution. 

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