Masters theses : Medicine

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Author: search.filters.author.Alnazeer Mohammed Ahmed HassanSubject: search.filters.subject.pulse wave analysis

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    Autonomic Activity and Haemodynamic Factors in the Clinical Severity of Sickle Cell Anaemia among Adults Sudanese -2018
    (Al-Neelain University, 2018) Alnazeer Mohammed Ahmed Hassan
    Introduction: Autonomic Nervous System (ANS) had been recently speculated as a contributor in Sickle Cell Anaemia (SCA) pathophysiology. Autonomic dysfunction in SCA can be involved in pain crises, vaso-occlusive crises and sudden death. Cardiovascular complications are a major cause of morbidity and mortality in SCA. Several haemodynamic disturbances were observed in SCA such as, higher Augmentation Index, Aortic and Brachial Pulse Pressures. Prediction of SCA severity is crucial for effective management and prevention of irreversible complications. Estimation of clinical severity in SCA is challenging, as it involves different body systems with variable expression of symptoms. Our objective was to study the relationships between autonomic nervous supply and haemodynamic characteristics and their impact on clinical severity among adult SCA patients. Subjects and Methods: This is a cross sectional hospital-based study conducted in the Military Hospital, Omdurman, including 35 Sudanese adults diagnosed with SCA in a steady state; and 25 healthy adults closely matched for age and gender as a comparison group. A standardized data collection tool was used to collect background variables, and record haemodynamic measurements and laboratory investigations. The collected data were entered to an online calculator predicting the clinical severity of SCA. The autonomic nervous supply and haemodynamic features were assessed by Heart Rate Variability and Pulse Wave Analysis respectively, both were obtained through SphygmoCor® Software version 9.0. The data were analysed by SPSS version 23. Descriptive statistics were used to summarize the data. Statistical analysis was carried out through One-Sample Kolmogorov-Smirnov to test the normal distribution of variables, Independent t-test, Mann Whitney U test to measure the statistically significant difference between means among SCA patients and the comparative group. The correlation analysis was used for assessing associations between study variables and multiple linear regression was applied to build a model predicting SCA clinical severity. All statistical tests were considered statistically significant when p-value < 0.05. Results: The BMI was significantly lower among SCA patients than the comparison group (p < 0.001). Total Power (overall autonomic supply) was lower among patients and HFM (parasympathetic supply) was significantly higher among SCA patients (p < 0.001). Augmentation pressure, augmentation index and aortic pulse pressure were significantly higher among SCA patients (p = 0.002, 0.012 and 0.013 respectively), but brachial diastolic blood pressure was significantly lower among them (p = 0.008). 48% of patients recorded a high mortality risk with clinical severity score > 0.72. A highly statistically significant model was formulated to predict the clinical severity score, with F test (7, 27) = 9.182, p-value < 0.001 and R = 0.839. Conclusion: The overall autonomic activity (sympathetic and parasympathetic) was impaired among SCA patients. Higher levels of augmentation pressure, augmentation index and aortic pulse pressure and lower level of brachial diastolic blood pressure were recorded among SCA patients, these results indicate increased risk of mortality. The clinical severity score was significantly predictable using a regression model involving heart rate variability, pulse wave analysis and TWBC. This reflects a significant impact of autonomic activity, TWBC, aortic diastolic, aortic pulse and brachial diastolic pressures on sickle cell anaemia morbidity and mortality. Recommendations: There is a need for advocacy of dealing with sickle cell anaemia as multi-organ disease, requiring multi-disciplinary medical approach for proper management. An encouragement of a health providers for evaluating the clinical events, precipitated by autonomic dysfunction or haemodynamic abnormalities as Electrocardiogram and Pulse Wave Analysis. Further studies on a larger scale are vital to address the relation between autonomic activity and clinical outcomes in SCA, also to validate and update existing clinical severity predictive models.