When a patient is hospitalized due to an arrhythmia, usually an untraceable atrial fibrillation, or due to a condition that forces him to bed, the doctor performs prevention for deep vein thrombosis and prescribes anticoagulants, usually heparin, as soon as possible.
Anticoagulants are used for the prevention and treatment of thromboembolic disorders. In general they do not dissolve the clot but prevent its formation and extension. When treatment with anticoagulants is started, the patient should be adequately informed about the benefits and potential risks associated with treatment.
It is also strongly recommended that the same sign a consent sheet containing detailed information on the advantages, disadvantages, risks and side effects of anticoagulant treatment. In general, the prescription of heparins, of which today are used those with low molecular weight, is the prevention of thromboembolism.
Generally heparins are used to prevent thrombosis into a immobilized patientn, classically due to fracture of the femur, or subjected to surgical interventions on pelvis, prostate, neoplasias. All these conditions have a tendency to produce blood clots inside the vessels and determine a venous thromboembolism. Subsequently, the treatment with heparin, in some pathologies, for ex. in patients with atrial fibrillation, oral anticoagulant therapy may be indicated in patients with a history of deep vein thrombosis.
These emboli can reach the heart through the venous
system and reach the right heart, hence the lung, where they cause the periculous
pulmonary embolism, characterized by intense chest pain, dyspnea and
shock, with danger to life itself of the patient.
Indications: pulmonary embolism, peripheral arterial embolism, prophylaxis and treatment of deep vein thrombosis, atrial fibrillation. Some cases of disseminated intravascular coagulopathy (CID). The scheme represents a clot in a pulmonary vessel that prevents, at the pulmonary level, gaseous exchanges and respiratory function (arrow).
Enhance the effects of antithrombin III.
They prevent the conversion of prothrombin to thrombin and at high doses, prevent the conversion of fibrinogen into fibrin. Therapeutic effect: prevention of thrombus formation and extension of pre-existing ones. Distribution: do not cross the placenta or enter the breast milk. Metabolization: removed from the endothelial reticulum system. Half-life: 1-2 hours (increases with increasing doses).
Contraindications:
hypersensitivity to heparin. Hypersensitivity to porcine or porcine proteins.
Bleedings in progress, history of bleeding from the digestive tract (when in
doubt performing an urgent gastroduodenoscopy before starting treatment), open
wounds, severe kidney or liver disease, serious infections.
Use with caution in: untreated hypertension. History of peptic ulcer. Cerebral
or medullary damage. Neoplasms. Last trimester of pregnancy and postpartum. Side
effects: bleeding, thrombocytopenia, hepatitis, rash, urticaria, fever,
hypersensitivity, osteoporosis (in prolonged treatments). Interactions:
antiplatelet, thrombolytic, cortisone, anti-inflammatory, quinidine,
cephalosporins and penicillins increase the risk of bleeding.
Laboratory test: before the treatment carry out: complete blood count, prothrombin time, partial thromboplastin time, urinalysis and fecal occult blood research. Partial thromboplastin time (PTT) and hematocrit should be monitored during treatment. When performing intermittent therapy with sodium heparin, the PTT should be measured 30 minutes before the next dose. When continuous infusion is used, the check should be performed 2 hours after starting the therapy. The platelets should be checked every 2-3 days. Overdose: the antinex of heparin is the protamine sulfate which, however, is administered via the IV route with great caution given the possibility of allergic reactions (in practice only with important or risky bleeding occurring). Not infrequently, given the short half-life of heparin, suspension is sufficient to get back to normal PTT values in a short time.
dosages
1. Treatment of thromboembolic events In case an immediate overgrowth is
required: a. Eparin sodium ev (Eparin BMS fl 5 mL) [1 mL = 5000 U]. Loading
dose: 75-100 U / kg. The loading dose significantly reduces the high risk of the
first hours. Next dose (continuous infusion): 15-25 U / kg / hr. If an immediate
anticoagulant effect is not considered necessary:
b. Low molecular weight heparins. Recent trials have documented the efficacy of
low molecular weight heparins (EBPM) in the treatment of thromboembolic events:
enoxaparin (Clexane). Pos: 100 U / Kg subcutaneously twice a day;
or
nadroparin (Fraxiparin). Pos: 180 U / kg / day;
or
dalteparin (Fragmin). Pos: 100 U / Kg / day subcutaneously twice or the entire
dose may be given as a single administration;
or
parnaparin (Fluxum). Pos: 6,400 U subcutaneously twice a day;
or
bemiparin (Ivor). Pos: subjects weighing <50 kg 5000 U under the skin; between
50 and
70 kg 7500 U subcutaneous; with weight> 70 kg 10000 U subcutaneous;
or
reviparin (Clivarina). Pos: 175 U / kg / day divided into 2 administrations.
LMWHs do not significantly modify the hemocoagulative parameters, so they do not
normally require laboratory controls. However, while traditional (unfractionated)
heparins are eliminated by the reticuloendothelial system, the LMWHs are partly
eliminated by the kidney and partly by the endothelium reticulum (with different
percentages between the individual EBPMs). Therefore, in patients with chronic
renal insufficiency or in the elderly with physiologically impaired renal
function, the LMWH may accumulate resulting in an increased risk of bleeding. In
these patients it is advisable to dose antiXa activity or give preference to
unfractionated heparins. The dose to be administered is different depending on
the type of EBPM, patient weight, renal function. The use of EBPM in subjects
weighing less than 45 kg or more than 100 kg, in children, pregnant women and
subjects with renal insufficiency has not yet been well established. or
c. Calcium heparin if (Chronoparin fl 0.5 mL). Pos: 12,500 U subcutaneously
every 8 hours [0,5 mL = 12,500 U].
treatment urate: after a thromboembolic event the treatment with epari-a is
carried out for 7-10 days and subsequently continued with oral anticoagulants
taking care to overlap the two treatments until the INR reaches the desired
range if using coumarinic
The efficacy in the prophylaxis of venous thrombosis in patients at risk is abundantly documented.
Several trials have documented the efficacy in unstable angina and non-Q infarction when associated with aspirin and / or other antiplatelet agents such as tirofiban, clopidogrel, abcximab. Despite some in vitro differences, those between the various EBPMs were inadequate or non-existent.
For this reason, the guidelines of various countries pose identical indications in the use of the various EBPMs. On the other hand, the Italian technical data sheets of the various EBPM report different indications from one heparin to another, often making the doctor run the risk of prescribing off labels; enoxaparin (Clexane). Pos: 4,000 U / day subcutaneous; or nadroparin (Fraxiparin). Pos: 3,100 U / day subcutaneous; or dalteparin (Fragmin). Pos: 2,500U / die subcutaneous; or parnaparin (Fluxum). Pos: 3,200 U / day subcutaneous. or bemiparin (Ivor). Pos: in subjects weighing <60 kg 2500 U underweight / subjects weighing> 60 kg 3500 U subcutaneous or reviparin (Clivarina). Pos: 1750 U / day subcutaneously. b. Calcium heparin if in low doses (Cronoeparin the 0.2 mL). Pos: 5.00 (1 11 subcutaneously every 8-12 hours [0.2 mL = 5,000 U] starting 2 hours before any surgical intervention c) Evine sodium heparin at low doses (Heparin BMS fl 5 mL) [1 mL = 5000 I | Pos: 5.000 U ev every 8-12 hours starting two hours before surgery.