A quick and reliable determination of the current coagulation is of great importance in the case of pronounced blood loss. The measurement of relevant coagulation parameters in the hospital laboratory usually takes too long for therapy control in an emergency.
Method: We have the prothrombin time (PT) and the activated partial thromboplastin time (APTT) in cardiac and abdominal surgery patients both with a bedside, laser photometric coagulation monitor (OCT) (CoaguChek Plus®, Boehringer Mannheim) and in the central laboratory (LAB) (Thromborel S or Pathromtin, KC 40, Canton).
Results: OCT and LAB values correlate highly significantly in the PT and APTT measurements (r = 0.92 and r = 0.91; p = 0.0001). Bias analyzes show an acceptable agreement for clinically relevant issues between the OCT and LAB systems, both for PT and APTT (relative error: 14.6% and 12%, respectively). With the tested OCT system, PT and APTT are available within 3 minutes, i.e., approx. Forty minutes earlier than with an emergency determination in the central laboratory.
Conclusion: On-site measurements of coagulation allow a reasonable indication and better control of a substitution or anticoagulation therapy perioperatively and can thus contribute to cost savings.
Turnaround time for analysis of prothrombin (PT) and activated partial thromboplastin time (APTT) by standard laboratory methods ranges between 40 min and several hours. The delay in obtaining the test results limits their clinical utility for treating perioperative coagulation disorders and adequate therapy. In this study, we compared on-site coagulation testing (OCT) of whole blood, which takes about 3 min, with standard laboratory plasma coagulation tests by our institutional laboratory (LAB) to assess the accuracy of the OCT in a clinical setting (abdominal and postcardiac surgery).
Methods. PT of 62 patients with abdominal surgery was measured intra- and postoperatively using LAB (KC 40, Thromborel S, Canton) and OCT ( Boehringer Mannheim) systems. APTT was determined by LAB- (KC 40, Pathromtin, Canton) and OCT methods in 53 patients who underwent cardiac surgery requiring cardiopulmonary bypass.
Results. Linear regression demonstrated a strong and significant (p = 0.0001) correlation of OCT- and LAB-determinations both for PT (r = 0.92) and APTT (r = 0.91). For PT testing, bias analyzes showed an agreement between OCT- and LAB-International Normalized Ratio (INR) (bias = 0.24; relative error = 14.6%) that was considered clinically acceptable, with 95% of the INR-differences lying between −0 .26 and +0.74 (mean ± 2 SD). Although commercial APTT reagents usually differ in their sensitivity to heparin, we also found an acceptable agreement between OCT and LAB-APTT values (bias = 6.7 s ± 22 s; mean ± 2 SD; relative error = 12%).
Conclusion. On-site coagulation monitoring provides a rapid, convenient, and accurate coagulation assessment that can guide specific therapy and optimize therapy control of coagulation disorders after cardiac and abdominal operations. Consequently, OCT offers a valuable tool to reduce the inappropriate use of fresh frozen plasma and improve cost-effectiveness.
When is the value changed?
In the case of a lack of vitamin K due to severe digestive disorders or artificial nutrition, and severe liver disorders, coagulation disorders can occur. The Quick value then falls below 70 percent, and the INR value rises above 1.1. For certain diseases, the doctor will prescribe medication, for example, with the active ingredient phenprocoumon, which reduces the blood’s ability to clot.
The doctor can set different target values!
INR guide value under anticoagulant therapy with coumarins:
for atrial fibrillation: 2.0 to 3.0
to avoid recurrence (relapse) after venous thrombosis / pulmonary embolism: 2.0 to 3.0
for artificial heart valves: 2.5 to 3.5
The Quick value was named after the first person to describe the method, A. Quick. A pathological test failure can be a congenital or acquired decrease in coagulation factors. The Quick value is influenced by the factors of the prothrombin complex FII, VII, X, and FV and a considerable reduction in fibrinogen. FVII deficiency is the most common cause of hereditary deficiencies in our population. In most cases, however, there is an acquired disorder:
- Liver synthesis disorder
- Vitamin K deficiency in the newborn or diet
- Intake of oral anticoagulants (caution: possibly with suicidal intent!)
Therapy control of oral anticoagulation (INR): The indication of the Quick value in percent for patients under oral anticoagulation is no longer recommended, as it does not take into account methodological differences (different measurement methods, reagents, and devices), for which reason s different target ranges for the Quick value result. That is why the INR value (INR = International Normalized Ratio) was introduced worldwide as a measure of anticoagulation to ensure comparability between different laboratories. It largely compensates for the laboratory-specific differences using a correction factor (ISI value). Caution: The INR only applies to patients in the stable phase of oral anticoagulation.
INR value: after venous thrombosis: 2.0 – 3.0
after arterial or venous thrombosis with antiphospholipid syndrome: 3.0 – 3.5
Anticoagulation of heart valve patients depending on the valve!
In Marcumar therapy, consider drug interactions (especially antibiotics) and the influence of vitamin K foods, especially all cabbage and green vegetables, raw sauerkraut, raw vegetables, raw meat, lettuce, and raw food carrots, strawberries, chocolate, tomatoes.
In Von Willebrand syndrome, a common disease, factor VIII deficiency is often too low to prolong the PTT. Patients with expected test results but with symptoms or signs of bleeding and positive family history should be tested for Von Willebrand syndrome; For this purpose, the Von Willebrand factor (vWF) antigen, the ristocetin cofactor activity (indirect test for large vWF multimers), the vWF multimer pattern and the factor VIII level are determined.
Hereditary hemorrhagic telangiectasia (also called Osler-Weber-Rendu syndrome) is a hereditary disorder of vascular malformation. People with this condition have small red to purple telangiectatic lesions on the face, lips, lining of the mouth and nose, and the tips of the fingers and toes. You can have recurrent bleeding from the nasal lining and gastrointestinal tract and other potentially severe consequences of arteriovenous malformations.
Thrombocytopenia
In thrombocytopenia, the peripheral blood smear often provides clues as to the cause.
If the smear is routine, it should be tested for HIV infection. If the result of the HIV test is negative and the patient is not pregnant and has not taken any medication known to cause platelet destruction, idiopathic thrombocytopenia is likely.
Bif the smear shows signs of hemolysis (fragmented RBCs on the smear, decreased hemoglobin levels), Thrombotic Thrombocytopenia Purpura (TTP), or Hemolytic Uremic Syndrome (HUS), it is suspected. “Classic” HUS occurs in patients with Shiga-like toxin-induced hemorrhagic colitis, which is associated with infections with multiple Escherichia coli serotypes. An “atypical” form of HUS occurs unusually in people with congenital abnormalities in the alternate complement pathway. The Coombs test is negative for TTP and HUS.
If the blood count and peripheral blood smear show other cytopenias or abnormal white blood cells, there may be multiple cell type hematological abnormalities. A bone marrow aspiration and biopsy are then necessary for diagnosis.
