Nursing Pharmacology Discussion: Anticoagulant Considerations before Starting Therapy
Please answer the following question:
The Nurse Practitioner is prescribing anticoagulant therapy. What diagnostic studies should she evaluate prior to initiation of therapy and why?
Anticoagulants: Considerations Before Starting Therapy
In addition to a valid indication, several patient factors also warrant consideration to determine if the risk of hemorrhage outweighs the benefit of therapy.
Baseline laboratory values including PT, INR, aPTT, urinalysis, CBC (with platelet count), and a liver profile are recommended before initiating anticoagulation. In women of childbearing age, laboratory testing for β-human chorionic gonadotropin is strongly encouraged to rule out pregnancy. Obtaining the patient’s telephone number and an alternative contact, such as a responsible family member or neighbor (obtain consent to contact others per HIPAA guidelines), is also advised. In addition, rule out any active major bleeding from the central nervous system (CNS) or gastrointestinal (GI) tract. A digital rectal examination or guaiac test to detect blood in the stool is recommended. A detailed medical, surgical, and medication history, including over-the-counter (OTC) medications and dietary supplements, is needed to assess the patient’s risk of bleeding events or inadequate anticoagulation. It is also important to document the indication for anticoagulation, which determines the duration of therapy, and, if warfarin is selected, to define the corresponding target INR, which defines the intensity of anticoagulation. When all these issues are addressed, anticoagulation is initiated (Witt, 2010). For patients receiving an LMWH or DOAC, body weight (kg), serum creatinine, and estimation of renal function creatinine clearance (CrCl) should be calculated. For patient receiving UFH, body weight (kg) should also be obtained. Although not currently recommended as a routine practice, a bleeding risk estimate for patients with AF may be obtained from calculating the HAS-BLED score and is discussed later in this chapter (http://www.mdcalc.com/has-bled-score-for-major-bleeding-risk/ or via a mobile phone app AnticoagEvaluator available from the ACC at http://www.acc.org/tools-and-practice-support/mobile-resources). The HAS-BLED score has only been validated in patients taking vitamin K antagonists (VKAs) and not in patients receiving parenteral anticoagulants or DOACs.
Arcangelo V. P., Peterson A. M., Wilbur V., & Reinhold J. A. (2016). Pharmacotherapeutics for Advanced Practice. [Yuzu]. Retrieved from https://reader.yuzu.com/#/books/9781496374066/
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Discussion Question: The Nurse Practitioner is prescribing anticoagulant therapy. What diagnostic studies should she evaluate prior to initiation of therapy and why?
Major classes of drugs that have been associated with serious adverse reactions over the decades are anticoagulants. There exist report cases on how the use of oral anticoagulants is more likely to result in prolonged hospital stays and hospitalization from effects such as bleeding (Di Micco & Monreal (2019). Due to their high potential for harm when used clinically, healthcare providers consider anticoagulants as high alert drugs. In this paper, the author reviews the diagnostic studies nurses should evaluate prior to initiating anticoagulant therapy. This knowledge is critical to nurses as it informs clinical decision making in regards to initiating management and monitoring progress.
Before initiating management with anticoagulants, the nurse should start with evaluating the patient to determine her overall risk of bleeding against benefits of anticoagulant therapy. The initial baseline laboratory tests that the nurse should order include; a Complete Blood Count (CBC), prothrombin time (PT), International normalized ratio (INR), and aPTT (Activated Partial Thromboplastin Time) (Harter, Levine & Henderson, 2015). The findings of a complete blood count can help to identify thrombocytopenia, which may be a pointer for a disorder involving the formation of a platelet plug, and is a risk factor for coagulopathy (Di Micco & Monreal, 2019). The PT and aPTT tests are the most crucial. The former assesses the common and extrinsic pathways by evaluating the time it takes to produce fibrin post activation of factor VII, while the latter helps to evaluate the time taken to generate fibrin in the intrinsic pathway (McCool, Muir & Knollmann-Ritschel, 2019).
A prolonged PT may be a pointer towards deficiency of a clotting factor (VII) often caused by inherited and artificial deficiencies, or presence of a circulating coagulation inhibitor. On the contrary, a prolonged aPTT may help the clinician to determine potential causes as acquired or inherited factor deficiencies such as hemophilia (Christmas disease), and hemophilia (McCool, Muir & Knollmann-Ritschel, 2019). Among women of reproductive age, the clinician must rule out the likelihood of a pregnancy by testing for β-human chorionic gonadotropin. The nurse must observe caution to evaluate for other causes of active bleeding from the GI system through either a guaiac test or a digital rectal examination (DRE). However, before ordering the aforementioned tests, the nurse should order for a comprehensive surgical, medical, and medication history, which further assesses a patient’s risk of bleeding.
Arcangelo et al. (2016) highlight that when initiating treatment, the nurse must write the indication, expected duration for therapy, and in the case of warfarin, the expected INR. When initiating therapy with unfractionated heparin (UFH), the clinician must obtain the patient’s body weight. In comparison, when initiating therapy with low molecular weight heparin (LMWH) the clinician must obtain additional measurements of serum creatinine (to determine the renal function creatinine clearance rate), and body weight.
References
Arcangelo V. P., Peterson A. M., Wilbur V., & Reinhold J. A. (2016). Pharmacotherapeutics for Advanced Practice. [Yuzu]. Retrieved from https://reader.yuzu.com/#/books/9781496374066/
Di Micco, P., & Monreal, M. (2019). Platelet count and bleeding in patients receiving anticoagulant therapy for venous thromboembolism: lesson from the RIETE registry. Journal of Blood Medicine, 10, 453.
Harter, K., Levine, M., & Henderson, S. O. (2015). Anticoagulation drug therapy: a review. The western journal of emergency medicine, 16(1), 11–17. https://doi.org/10.5811/westjem.2014.12.22933
McCool, I. E., Muir, J. M., & Knollmann-Ritschel, B. (2019). Educational Case: The Bleeding Patient. Academic pathology, 6, 2374289519886042. https://doi.org/10.1177/2374289519886042
