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- Heenkenda, Menikae Kanchena, 1982-
(författare)
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Understanding and Managing Thrombotic Risks in Medical Conditions : One Size Does Not Fit All
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hemostasis is a critical physiological process that stops bleeding at the site of an injury while ensuring normal blood flow elsewhere, thereby preventing excessive clot formation that could lead to dangerous conditions like thrombosis. This delicate balance is influenced by genetics, medical conditions such as cancer, and various medications. When a blood vessel is damaged, platelets adhere to the exposed area, become activated, and aggregate to form an initial plug. Coagulation factors, particularly thrombin, create a strong fibrin network to stabilize the clot. Disruptions in this process can result in significant bleeding or dangerous clot formation.This thesis aims to explore and understand the factors affecting coagulation and the risks of thrombotic events in different medical contexts. This includes studying genetic variability in the protease-activated receptor 4 (PAR4) gene (specifically the Ala120Thr variant) among sub-Saharan African populations, identifying genetic and non-genetic risk factors for venous thromboembolism (VTE) in patients with the brain cancer glioblastoma multiforme (GBM), and investigating the impact of intravenous morphine on platelet activity in patients with ST-elevation myocardial infarction (STEMI) treated with ticagrelor, a P2Y12 inhibitor. The A allele of the rs773902 single-nucleotide polymorphism (SNP) in the PAR4 gene (F2RL3) substitutes threonine for alanine at the 120th protein position (Thr120). This allele is more prevalent in African populations compared to Caucasian populations, although previous studies did not specify the geographic ancestry of participants. Thr120 is associated with higher PAR4-induced human platelet aggregation and Ca2+ flux. Our study found that the frequency of the A allele in the Somali population is significantly lower than previously reported for African Americans. The A allele frequency in Somalis is 38%, compared to 63% for African Americans. The A allele frequency in Somalis is closer to that of the Maasai population in Kenya (41%), but vastly different from the Esan population in Nigeria (68%). Certain cancers, such as GBM, are associated with a higher risk of VTE, including deep vein thrombosis (DVT) and pulmonary embolism (PE). Our research identified blood group B as a significant risk factor for patients with GBM (OR=6.91; 95% CI=2.2–24.1; P =0.001). Also, GBM tumors in the frontal lobe are associated with an increased risk of VTE (OR=3.14; 95% CI=1.1–10.7; P =0.05). Our study on morphine, commonly used for pain management in STEMI patients, found that morphine is associated with increased platelet aggregation one hour after percutaneous coronary intervention (PCI), impacting the efficacy of ticagrelor. Morphine delays platelet inhibition by affecting the pharmacodynamics of antiplatelet therapy, likely by delaying gastric emptying. However, this effect is short-lived, as platelet reactivity returns to similar levels in both groups 12 hours post-PCI. Despite this immediate impact on platelet function, our research found no significant differences in biomarkers of platelet activity, coagulation, or inflammation between the morphine and non-morphine groups. Additionally, all patients in our study were administered unfractionated heparin injections or bivalirudin infusion during primary PCI, which may help control the risk of blood clot formation. These studies collectively emphasize the need for individualized strategies to manage thrombotic risks and coagulation. The significant genetic variability among sub-Saharan African populations highlights the need for precise genetic research to understand how genetics influence coagulation and develop personalized medical strategies. The increased risk of cancer-associated thrombosis, particularly in patients with GBM, calls for individualized anticoagulant therapies based on unique risk profiles, such as blood group typing and tumor location. Incorporating these insights into clinical practice can help healthcare providers better identify high-risk patients and tailor thromboprophylaxis strategies accordingly. Similarly, the impact of morphine on patients with STEMI treated with ticagrelor requires careful consideration. In conclusion, these findings underscore the importance of a personalized approach in managing coagulation and thrombotic risks. The studies show that genetic variability, specific medical conditions, and medication effects are crucial in thrombotic risk. Therefore, customized strategies based on individual patient profiles and contexts are essential for effectively managing and preventing thrombotic events.
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| 2. |
- Claesson Lingehall, Helena, 1965-
(författare)
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Delirium in older people after cardiac surgery : risk factors, dementia, patients’ experiences and assessments
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background:Delirium is common in older people undergoing cardiac surgery. Delirium is an acute or subacute neuro-psychiatric syndrome, characterized by a change in cognition, disturbances in consciousness; it fluctuates, develops over a short period of time and always has an underlying cause. It is associated with a disturbance in psychomotor activity, and is classified according to different clinical profiles such as hypoactive, hyperactive and mixed delirium. Delirium after cardiac surgery is not harmless, it increases the risk of complications such as prolonged stay in hospital, falls, reduced quality of life, reduced cognitive function and increased mortality.Aim:The overall aim of this thesis was to investigate postoperative delirium in older people undergoing cardiac surgery with Cardiopulmonary Bypass (CPB), focusing on risk factors, dementia and patients’ experiences; and to evaluate an assessment for screening delirium.Methods:This thesis compromises four studies. All participants (n=142) were scheduled for cardiac surgery with use of CPB at the Cardiothoracic Surgery Department, Heart Centre, Umeå University Hospital, Sweden, between February and October 2009. Six structured interviews were conducted preoperatively, day one and day four postoperatively, and in home visits, one, three and five years after surgery (2010, 2012 and 2014). The assessment scales used in Studies I, II and IV were: the Mini-Mental State Examination (MMSE) for cognition, the Organic Brain Syndrome Scale (OBS) for delirium, Geriatric Depression Scale 15 (GDS-15) for depression, Katz staircase with Activities of Daily Living (ADL) for participants’ functional status and the Numerical Rating Scale (NRS) for pain. During the hospital stay, nursing staff used the Swedish version of the Nursing Delirium Screening Scale (Nu-DESC) to assess delirium. Semi-structured interviews were also carried out (III) in the one-year follow up. Delirium, dementia and depression were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (DSM IV TR).Results: Out of 142 participants 54.9% (78/142) developed delirium after cardiac surgery (I). Independent risk factors, predisposing and precipitating, associated with delirium were: age, diabetes, gastritis/peptic ulcer, volume load during operation, longer time on ventilator in intensive care, increased temperature and plasma sodium concentration in the intensive care unit. Out of 114 participants thirty (26.3%) developed dementia within the five years of follow-up. It was shown that a lower preoperative MMSE score and postoperative delirium were factors independently associated with development of dementia (II). One year after cardiac surgery, participants diagnosed with postoperative delirium described in detail feelings of extreme vulnerability and frailty. Despite this, the participants were grateful for the care they had received (III). Hypoactive was the most common symptom profile for delirium. The Swedish version of Nu-DESC showed high sensitivity in detecting hyperactive delirium, but low sensitivity in detecting hypoactive delirium (IV).Conclusion:Delirium was common among older patients undergoing cardiac surgery. Both predisposing and precipitating factors contributed to postoperative delirium. Preventive strategies should be considered in future randomized studies. It might also be suggested that cognitive function should be screened for preoperatively and patients who develop delirium should be followed up to enable early detection of symptoms of dementia. Whether prevention of postoperative delirium can reduce the risk of future dementia remains to be studied. To minimise unnecessary suffering, patients and next of kin should be informed about and prepared for the risk of delirium developing during hospitalization. The Swedish version of Nu-DESC should be combined with cognitive testing to improve detection of hypoactive delirium, but further research is needed. Healthcare professionals need knowledge concerning postoperative delirium in order to prevent, detect and treat delirium so as to avoid and relieve the suffering it might cause.
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