Venous thromboembolism is a medical complication but increases after any recent surgery. Accordin... more Venous thromboembolism is a medical complication but increases after any recent surgery. According to Virchow's triad the risk increases with spinal surgery owing to prolonged operative procedures, manipulation of great vessels (endothelial injury), prone positioning and postoperative bed rest (stasis). Patients are also often high-risk patients for DVT and their risk is compounded by increased age, smoking habit, hypertension, diabetes, cancer and dehydration (hypercoagulable state).
The ENDORSE study 1 found that, globally, more than 50% of hospitalised patients are at risk of V... more The ENDORSE study 1 found that, globally, more than 50% of hospitalised patients are at risk of VTE, with adequate prophylaxis (according to the 7th American College of Chest Physicians (ACCP) guidelines) being given to approximately only 58% of surgical patients and 40% of medical patients. The 8th ACCP guidelines 2 were published in 2008, followed in 2009 by the South African guidelines. 3 Despite consensus and approved guidelines, many patients at risk either do not receive prophylaxis, or receive inadequate prophylaxis. The TUNE-IN study was conducted to evaluate common practice in the assessment of VTE risk and concurrent prescription of prophylaxis in the private healthcare setting in South Africa. Perceived clinical VTE risk, actual VTE risk scoring (using an approved risk assessment model-modified Caprini risk assessment model), actual VTE prophylaxis prescribed, and mobilisation at varying post-discharge dates were collected. Methods Settings and patients All patients were enrolled between May 2008 and November 2008 in a regional, prospective, cross-sectional and longitudinal, noninterventional, multi-site, observational study. Twenty consecutive patients, admitted for a minimum of one night, were evaluated at each of 29 sites across Gauteng by specialist physicians and surgeons. The sites were selected on the basis that they practised standard care in terms of VTE profiling and prophylaxis among private practitioners in Gauteng. As this condition might result in bias, the selection may not reflect standard of care in all private and public hospitals, but is likely to be a fair representation of practice across the country. Data collection Participating sites, when introduced to the study, were asked to evaluate patients at risk for VTE clinically, without using any official scoring system. The patients were then re-evaluated via an approved risk assessment model (RAM)-modified Caprini risk score (Table I). This scoring system assigns different risk factors a specific point value. The total VTE risk is then calculated by adding the risk factors and the patient is then assigned to a risk category (low, moderate, high and highest groups) (Table II). The decision about VTE prophylaxis prescription was left to the treating physician/surgeon, but the recommended VTE prophylaxis for each group was supplied with the RAM. A bleeding risk reminder was also given with the risk assessment form (Table III). Specific recommendations given by the doctor for that specific patient were noted (Fig. 1). No risk factor score for HIV disease was given; however, as it is a significant risk for VTE, it was noted as an additional comment. Upon discharge, the patient's mobility and VTE prophylaxis were evaluated. Follow-up assessment of mobility was carried out telephonically on days 3, 7 and 14 (Fig. 1).
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, 2013
The development of novel oral anticoagulants that are effective alternatives to warfarin in non-v... more The development of novel oral anticoagulants that are effective alternatives to warfarin in non-valvular atrial fibrillation (AF) is a welcome advance. However, a variety of unresolved problems with their use, and not least with their cost, make it important to re-evaluate the use of warfarin as it will likely remain the anticoagulant of choice in South African patients with non-valvular AF for the foreseeable future. In this article, we review the correct clinical use of warfarin. Guidance is provided on commencing warfarin treatment, maintenance dosing, the recommended steps when temporary withdrawal of treatment is necessary, the management of bleeding, and the use of warfarin in chronic kidney disease. Techniques for changing from warfarin to one of the new oral anticoagulants and vice versa are included.
This guideline reflects current best practice. However, every patient should still be assessed on... more This guideline reflects current best practice. However, every patient should still be assessed on merit, with individualisation of therapy where indicated. Special attention is needed in geriatric and obese patients, those with renal dysfunction and those with concomitant medical disorders. Drug recommendations are based on Medicines
Stroke is one of the leading causes of death worldwide. Formation of a fibrin clot is controlled ... more Stroke is one of the leading causes of death worldwide. Formation of a fibrin clot is controlled by a group of tightly regulated plasma proteases and cofactors and a change in the fibrin fiber formation causes an alteration in clot morphology. This plays an important role during thrombotic events. In the current study we investigated the ultrastructure of fibrin networks from fifteen ischemic stroke patients by using scanning electron microscopy. Clot morphology was investigated with and without the addition of human thrombin to the platelet rich plasma. Previously it was shown that, when studying the ultrastructure of fibrin networks, the addition of thrombin is necessary to form an expansive, fully coagulated layer of fibers. Results from the addition of thrombin to the plasma showed thick, matted fibrin fibers and a net covering some of the major fibers in stroke patients. Typical control morphology with major thick fibers and minor thin fibers could be seen in some areas in the stroke patients. In stroke patients, without the addition of thrombin, a matted fibrin network still formed, indicating that the factors responsible for the abnormal fibrin morphology are present in the circulating plasma and is the cause of the observed matted, layered morphology. This is not present in healthy individuals. From the results obtained we suggest that this changed morphology might be useful in a screening regime to identify the possibility of a stroke or even to follow the progress of stroke patients after treatment.
Southern African Journal of Gynaecological Oncology, 2012
The relationship between cancer and thrombosis has been known for many years. Thrombotic risk is ... more The relationship between cancer and thrombosis has been known for many years. Thrombotic risk is increased in the patient with cancer, and the diagnosis of venous thromboembolism at the time that a malignancy presents influences patient outcome. Risk evaluation, prophylaxis and treatment of venous thromboembolism are practical issues that face doctors who are dealing with these patients.
COVID-19 is associated with a hypercoagulable state that may present as pulmonary thrombosis, pul... more COVID-19 is associated with a hypercoagulable state that may present as pulmonary thrombosis, pulmonary embolism, and venous and arterial thrombosis. Suggested pathogenesis include direct infection of the endothelial cell with subsequent endothelial cell dysfunction, leading to increased procoagulant activity, decreased anticoagulant activity and decreased fibrinolysis. The severe immune inflammatory response in the lungs with cytokine release also plays a critical role (immunothrombosis). Hypoxia has a local and systemic effect on coagulation. Various markers of this state have been described, and especially the D-dimer level (and rapid changes in the D-dimer level) as a reliable prognostic marker. It is also used as indicator for initiation of anticoagulation by some experts. Due to the pleotrophic effects of heparin, it is the anticoagulant of choice for these patients (most often low molecular weight heparin, due to decreased risk of heparin induced thrombocytopenia, ease of us...
Southern African Journal of Gynaecological Oncology, 2018
This summary was first published in SAJGO in 2012, but due to newer drugs available and the publi... more This summary was first published in SAJGO in 2012, but due to newer drugs available and the publication of a new guidance paper 13 as well as the International Guideline for treatment and prophylaxis of VTE in the cancer patient, 2 on request of the publisher, an update is given.
Although the benefits of the novel oral anticoagulants (dabigatran, rivaroxaban, and apixaban) ma... more Although the benefits of the novel oral anticoagulants (dabigatran, rivaroxaban, and apixaban) may surpass warfarin in non-valvular atrial fibrillation (AF), their high cost makes them unaffordable to most South Africans. Therefore, it remains imperative that optimal management of warfarin anticoagulation is provided to these patients. Warfarin’s superiority over antiplatelet therapies in preventing stroke and systemic embolism in patients with non-valvular AF has been firmly established for more than a decade. Warfarin reduces stroke risk by 68%. [1] Optimal results depend on maintenance of the international normalised ratio (INR) within the therapeutic range (INR 2 - 3). Lower values are associated with an excess of thrombo-embolic events and higher values with increased bleeding. [2,3] Notably, in clinical trials and in practice the ideal therapeutic effect is obtained in less than half of all patients, in the remainder, almost 40% are in a sub-therapeutic range while approximate...
Venous thromboembolism is a medical complication but increases after any recent surgery. Accordin... more Venous thromboembolism is a medical complication but increases after any recent surgery. According to Virchow's triad the risk increases with spinal surgery owing to prolonged operative procedures, manipulation of great vessels (endothelial injury), prone positioning and postoperative bed rest (stasis). Patients are also often high-risk patients for DVT and their risk is compounded by increased age, smoking habit, hypertension, diabetes, cancer and dehydration (hypercoagulable state).
The ENDORSE study 1 found that, globally, more than 50% of hospitalised patients are at risk of V... more The ENDORSE study 1 found that, globally, more than 50% of hospitalised patients are at risk of VTE, with adequate prophylaxis (according to the 7th American College of Chest Physicians (ACCP) guidelines) being given to approximately only 58% of surgical patients and 40% of medical patients. The 8th ACCP guidelines 2 were published in 2008, followed in 2009 by the South African guidelines. 3 Despite consensus and approved guidelines, many patients at risk either do not receive prophylaxis, or receive inadequate prophylaxis. The TUNE-IN study was conducted to evaluate common practice in the assessment of VTE risk and concurrent prescription of prophylaxis in the private healthcare setting in South Africa. Perceived clinical VTE risk, actual VTE risk scoring (using an approved risk assessment model-modified Caprini risk assessment model), actual VTE prophylaxis prescribed, and mobilisation at varying post-discharge dates were collected. Methods Settings and patients All patients were enrolled between May 2008 and November 2008 in a regional, prospective, cross-sectional and longitudinal, noninterventional, multi-site, observational study. Twenty consecutive patients, admitted for a minimum of one night, were evaluated at each of 29 sites across Gauteng by specialist physicians and surgeons. The sites were selected on the basis that they practised standard care in terms of VTE profiling and prophylaxis among private practitioners in Gauteng. As this condition might result in bias, the selection may not reflect standard of care in all private and public hospitals, but is likely to be a fair representation of practice across the country. Data collection Participating sites, when introduced to the study, were asked to evaluate patients at risk for VTE clinically, without using any official scoring system. The patients were then re-evaluated via an approved risk assessment model (RAM)-modified Caprini risk score (Table I). This scoring system assigns different risk factors a specific point value. The total VTE risk is then calculated by adding the risk factors and the patient is then assigned to a risk category (low, moderate, high and highest groups) (Table II). The decision about VTE prophylaxis prescription was left to the treating physician/surgeon, but the recommended VTE prophylaxis for each group was supplied with the RAM. A bleeding risk reminder was also given with the risk assessment form (Table III). Specific recommendations given by the doctor for that specific patient were noted (Fig. 1). No risk factor score for HIV disease was given; however, as it is a significant risk for VTE, it was noted as an additional comment. Upon discharge, the patient's mobility and VTE prophylaxis were evaluated. Follow-up assessment of mobility was carried out telephonically on days 3, 7 and 14 (Fig. 1).
South African medical journal = Suid-Afrikaanse tydskrif vir geneeskunde, 2013
The development of novel oral anticoagulants that are effective alternatives to warfarin in non-v... more The development of novel oral anticoagulants that are effective alternatives to warfarin in non-valvular atrial fibrillation (AF) is a welcome advance. However, a variety of unresolved problems with their use, and not least with their cost, make it important to re-evaluate the use of warfarin as it will likely remain the anticoagulant of choice in South African patients with non-valvular AF for the foreseeable future. In this article, we review the correct clinical use of warfarin. Guidance is provided on commencing warfarin treatment, maintenance dosing, the recommended steps when temporary withdrawal of treatment is necessary, the management of bleeding, and the use of warfarin in chronic kidney disease. Techniques for changing from warfarin to one of the new oral anticoagulants and vice versa are included.
This guideline reflects current best practice. However, every patient should still be assessed on... more This guideline reflects current best practice. However, every patient should still be assessed on merit, with individualisation of therapy where indicated. Special attention is needed in geriatric and obese patients, those with renal dysfunction and those with concomitant medical disorders. Drug recommendations are based on Medicines
Stroke is one of the leading causes of death worldwide. Formation of a fibrin clot is controlled ... more Stroke is one of the leading causes of death worldwide. Formation of a fibrin clot is controlled by a group of tightly regulated plasma proteases and cofactors and a change in the fibrin fiber formation causes an alteration in clot morphology. This plays an important role during thrombotic events. In the current study we investigated the ultrastructure of fibrin networks from fifteen ischemic stroke patients by using scanning electron microscopy. Clot morphology was investigated with and without the addition of human thrombin to the platelet rich plasma. Previously it was shown that, when studying the ultrastructure of fibrin networks, the addition of thrombin is necessary to form an expansive, fully coagulated layer of fibers. Results from the addition of thrombin to the plasma showed thick, matted fibrin fibers and a net covering some of the major fibers in stroke patients. Typical control morphology with major thick fibers and minor thin fibers could be seen in some areas in the stroke patients. In stroke patients, without the addition of thrombin, a matted fibrin network still formed, indicating that the factors responsible for the abnormal fibrin morphology are present in the circulating plasma and is the cause of the observed matted, layered morphology. This is not present in healthy individuals. From the results obtained we suggest that this changed morphology might be useful in a screening regime to identify the possibility of a stroke or even to follow the progress of stroke patients after treatment.
Southern African Journal of Gynaecological Oncology, 2012
The relationship between cancer and thrombosis has been known for many years. Thrombotic risk is ... more The relationship between cancer and thrombosis has been known for many years. Thrombotic risk is increased in the patient with cancer, and the diagnosis of venous thromboembolism at the time that a malignancy presents influences patient outcome. Risk evaluation, prophylaxis and treatment of venous thromboembolism are practical issues that face doctors who are dealing with these patients.
COVID-19 is associated with a hypercoagulable state that may present as pulmonary thrombosis, pul... more COVID-19 is associated with a hypercoagulable state that may present as pulmonary thrombosis, pulmonary embolism, and venous and arterial thrombosis. Suggested pathogenesis include direct infection of the endothelial cell with subsequent endothelial cell dysfunction, leading to increased procoagulant activity, decreased anticoagulant activity and decreased fibrinolysis. The severe immune inflammatory response in the lungs with cytokine release also plays a critical role (immunothrombosis). Hypoxia has a local and systemic effect on coagulation. Various markers of this state have been described, and especially the D-dimer level (and rapid changes in the D-dimer level) as a reliable prognostic marker. It is also used as indicator for initiation of anticoagulation by some experts. Due to the pleotrophic effects of heparin, it is the anticoagulant of choice for these patients (most often low molecular weight heparin, due to decreased risk of heparin induced thrombocytopenia, ease of us...
Southern African Journal of Gynaecological Oncology, 2018
This summary was first published in SAJGO in 2012, but due to newer drugs available and the publi... more This summary was first published in SAJGO in 2012, but due to newer drugs available and the publication of a new guidance paper 13 as well as the International Guideline for treatment and prophylaxis of VTE in the cancer patient, 2 on request of the publisher, an update is given.
Although the benefits of the novel oral anticoagulants (dabigatran, rivaroxaban, and apixaban) ma... more Although the benefits of the novel oral anticoagulants (dabigatran, rivaroxaban, and apixaban) may surpass warfarin in non-valvular atrial fibrillation (AF), their high cost makes them unaffordable to most South Africans. Therefore, it remains imperative that optimal management of warfarin anticoagulation is provided to these patients. Warfarin’s superiority over antiplatelet therapies in preventing stroke and systemic embolism in patients with non-valvular AF has been firmly established for more than a decade. Warfarin reduces stroke risk by 68%. [1] Optimal results depend on maintenance of the international normalised ratio (INR) within the therapeutic range (INR 2 - 3). Lower values are associated with an excess of thrombo-embolic events and higher values with increased bleeding. [2,3] Notably, in clinical trials and in practice the ideal therapeutic effect is obtained in less than half of all patients, in the remainder, almost 40% are in a sub-therapeutic range while approximate...
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Papers by Pieter Wessels