Venous thromboembolism (VTE) is a critical condition characterized by high levels of pulmonary embolism as well as deep vein thrombosis. It involves the presence of blood clots that find their way into the lungs (pulmonary embolism) or remain in the venous blood stream. In the view of Wang et al. (2013), venous thromboembolism can be fatal when it has affected the lungs and causes interference with the normal supply of blood. In deep vein thrombosis, the blood clot is present in the leg or arm deep veins. Experts have identified obesity as a risk factor that increases the likelihood to develop venous thromboembolism. Specifically, obese individuals are two or three times vulnerable to developing venous thromboembolism compared to the rest of the population. Moreover, cases of delayed diagnosis of venous thromboembolism are prevalent among obese people. In the case of pulmonary embolism, surgery is one of the effective treatment alternatives that seek to remove the blood clot from the lungs. However, more than 50% of obese patients do not survive after the operation. For this reason, it is explicit that obesity reduces the survival rates for individuals with pulmonary embolism and makes the condition more fatal.
Based on these statistics, it is imperative to carry out venous thromboembolism prophylaxis to prevent serious cases of pulmonary embolism or deep vein thrombosis. Clinicians use heparin to carry out venous thromboembolism prophylaxis. As highlighted by Vandiver, Ritz, and Lalama (2015), clinicians have to make important decisions on whether to use unfractionated or low-molecular-weight heparin (LMWH) when carrying out prophylaxis to prevent the occurrence of venous thromboembolism. Moreover, clinicians have to determine the most effective dosage for the selected heparin. Specifically, it is a requirement for clinicians to carry out dosage adjustment depending on the patient’s weight when treating venous thromboembolism. However, in the prophylaxis cases, clinicians have been using fixed doses. When using unfractionated heparin, clinicians give their patients 5000 units taken twice or thrice a day. When using enoxaparin, clinicians prescribe 40mg taken once each day.
Despite the specifications for the fixed doses for venous thromboembolism prophylaxis, there is a major concern when dealing with morbidly obese people who have a body mass index above 40. The lack of specific guidelines on how to determine the proper dosages for this population presents a major challenge for clinicians. Wang et al. (2013) assert that many clinicians prescribe the 40mg enoxaparin administered through the subcutaneous route twice each day. However, clinicians may also opt to prescribe the unfractionated heparin for morbidly obese people with the core objective of preventing venous thromboembolism. However, for this prophylaxis to be successful, a dosage of 7500 units administered through the subcutaneous root thrice a day is more considerable. When handling morbidly obese individuals, it is imperative to monitor the anti-factor Xa levels as a critical determinant for the proper dosage. Unfortunately, the monitoring of Xa levels is not applicable in all situations because research is yet to define a universally acceptable level of this anti-factor in cases of venous thromboembolism prophylaxis. In any case, many trials conducted in the past have been unable to establish the link between the Xa levels and the thrombotic events.
The available evidence demonstrates that fixed dosages of venous thromboembolism prophylaxis do not register optimal effects in morbidly obese people. Based on the existing negative correlation between anti-factor Xa levels and the patient’s body weight, it is recommendable to use the fixed dose of enoxaparin 40mg administered two times a day or determine the proper dosing regimen based on the patient’s body weight. As highlighted by Vandiver, Ritz, and Lalama (2015), the recommended dosing regimen, in this case, is 0.5mg/kg/day when handling obese patients. However, it is imperative to increase the dose of low-molecular-weight heparin by 30% if the patient’s body mass index is above 40. Undoubtedly, it is important to increase the dosages of unfractionated heparin or enoxaparin when dealing with patients whose weight is above 100kg and body mass index is beyond 40.
Recent studies have demonstrated that individuals with a body mass index above 40 do not respond effectively to the fixed dosages of venous thromboembolism prophylaxis. One of the recent studies compared the effect of prophylaxis between two groups that received higher doses of the prophylaxis and the standard fixed doses respectively (Wang et al., 2013). Based on this study, patients characterize as morbidly obese registered higher cases of venous thromboembolism if they received the standard doses. However, morbidly obese patients who received higher dosages of unfractionated heparin and enoxaparin registered a significant reduction of venous thromboembolism. Based on the findings from this study, it is recommendable to use higher dosages of unfractionated heparin and enoxaparin when dealing with morbidly obese patients.
- Vandiver, J., Ritz, L., & Lalama, J. (2015). Chemical prophylaxis to prevent venous thromboembolism in morbid obesity: literature review and dosing recommendations. Journal of Thrombosis and Thrombolysis, 41(3), 475-481.
- Wang, T., Milligan, P., Wong, C., Deal, E., Thoelke, M., & Gage, B. (2013). Efficacy and safety of high-dose thromboprophylaxis in morbidly obese inpatients. Thrombosis and Haemostasis, 111(1), 88-93.