Point‐of‐care testing in haemostasis

Abstract

SummaryPoint-of-care testing (POCT) in haematology has seen a significant increase in both the spectrum of tests available and the number of tests performed annually. POCT is frequently undertaken with the belief that this will reduce the turnaround time for results and so improve patient care. The most obvious example of POCT in haemostasis is the out-ofhospital monitoring of the International Normalized Ratio in patients receiving a vitamin K antagonist, such as warfarin. Other areas include the use of the Activated Clotting Time to monitor anticoagulation for patients on cardio-pulmonary bypass, platelet function testing to identify patients with apparent aspirin or clopidogrel resistance and thrombelastography to guide blood product replacement during cardiac and hepatic surgery. In contrast to laboratory testing, POCT is frequently undertaken by untrained or semi-trained individuals and in many cases is not subject to the same strict quality control programmes that exist in the central laboratory. Although external quality assessment programmes do exist for some POCT assays these are still relatively few. The use of POCT in haematology, particularly in the field of haemostasis, is likely to expand and it is important that systems are in place to ensure that the generated results are accurate and precise.Keywords: point-of-care testing, haemostasis, quality assurance, near patient testing.Point-of-care testing (POCT) is defined as a diagnostic test at or near the site of the patient with the rationale that such testing will result in the rapid generation of results and improve patient care. POCT is frequently undertaken by nonlaboratory personnel both within and outwith the hospital setting and the last 10 years has seen a significant increase in its use, particularly in the field of haemostasis. The importance of POCT is highlighted by a recent publication from the This review summarizes POCT in relation to haemostasis, and complements a previously published guideline by the British Committee for Standards in Haematology on POCT in Haematology (Briggs et al, 2008).

Point-of-care test (POCT) INR: hope or illusion?

“…There was no difference in incidence of new thromboembolic events and bleeding, which showed that patients were able to correctly adjust the anticoagulant dose. However, the authors warned that not all patients are capable of performing the monitoring of anticoagulant therapy [10].…”

“…These antibodies neutralize phospholipids included in the test to begin the cascade activation of coagulation factors, slowing down time for the formation of thrombin and thus interfere with the results provided by the devices that monitor the generation of thrombin and a subsequent substrate cleavage [ 24]. Other factors that may influence are the presence of hyperbilirubinemia (> 170 mmol / L) and hypertriglyceridemia (> 5 mmol / L), which interfere in the blood viscosity and therefore in the results of the equipment that determines both blood electromagnetic impedance change, such as those that monitor capillary blood flow and detect the movement of metal particles in a magnetic field and reflect the light [10,15].…”

“…The thrombin-substrate reaction generates the electrochemically inert tripeptide (PhePipecolina -arginine) and the electroactive compound (NH3 @ + -C6H4 -NH -C6H4 -OCH3), which is detected by amperage. This time represents the thrombin generation period [10].…”

“…The International Sensitivity Index Calibration System approves INR-POCT results only when the values are lower than 4.5 [10]. Thus, this test is not suitable for patients with valve metal, for which the therapeutic range of INR is between 2.5 and 3.5 [23].…”

“…Tests which require more blood may induce compression to increase the puncture site bleeding, which is not desirable, since it changes the test results [10]. In addition to these limitations, some patients have difficulty in collecting the blood drop and snap the cartridge into the coagulometer, particularly for individuals with arthritis or tremors [8].…”