An evaluation of central and cerebral haemodynamic interactions in chronic obstructive pulmonary disease

Al Shezawi, Mahfoudha 2021. An evaluation of central and cerebral haemodynamic interactions in chronic obstructive pulmonary disease. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Abstract Background: Chronic obstructive pulmonary disease (COPD) is characterised by airflow obstruction, an independent predictor of increased cardiovascular risk including stroke. Cardiovascular risk can be predicted by central haemodynamics including arterial stiffness as measured by aortic pulse wave velocity (aPWV) and central pulse pressure (CPP) in addition to cerebral haemodynamics as measured by middle cerebral artery pulsatility index (MCAPI). Arterial stiffness is increased in COPD, which may be linked to the cerebral haemodynamics and risk of stroke. This study aimed to investigate the associations between central and cerebral haemodynamics and measures of health status in patients with COPD compared to aged-matched controls. Method: The thesis comprises of three studies: • A longitudinal study included three assessment timepoints (baseline, 2 and 6 years) in patients with COPD and controls. Detailed arterial assessments included aPWV and CPP using the SphygmoCor system. Lung function was assessed using forced expiratory volume in the first second/ forced vital capacity (FEV1/FVC) measured using spirometry. Health status included the measurement of physical function using the validated Time-Up-and-Go test (TUG) and the Six-minute Walking Test (6MWT), as well as subjective measures including the Comprehensive Geriatric Assessment (CGA), the COPD Assessment tool (CAT) and the St George's Respiratory Questionnaire (SGRQ). • A cross-sectional study investigating the differences in patients with COPD and controls included all above assessments, with the addition of middle cerebral artery pulsatility index (MCAPI) using transcranial Doppler ultrasound. • A cross-sectional study investigated differences in cerebral volumes (white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF) volumes) using MRI in patients with COPD and controls. iii Results: • The longitudinal study included 75 patients with COPD and 71 controls. At each assessment time-point, aPWV remained significantly higher in COPD patients than controls but both groups showed a similar change in aPWV. After 6 years, patients with COPD had lower FEV1/FVC and physical function as measured by the TUG, 6MWT and CGA, all were related to aPWV (all p<0.05). • The cross-sectional study included 45 patients with COPD and 50 controls. MCAPI was similar in COPD and controls. In COPD, MCAPI was significantly associated with CPP (r=0.433, P=0.003) and FEV1/FVC (r=0.330, P=0.027), but not aPWV. In controls, MCAPI was associated with CPP (r=0.601, P=0.001) and aPWV (r=0.452, P=0.001). In COPD, using Stepwise Multiple Regression Analysis, CPP remained an independent predictor of MCAPI (P=0.003). • Pilot data from 6 patients with COPD and 6 aged and gender-matched controls showed no difference in cerebral volumes between the groups. MCAPI was associated with GM and CSF volumes, with no association between aPWV or CPP and cerebral volumes. Conclusion: Patients with COPD have increased arterial stiffness, cardiovascular comorbidities and poorer health status compared to matched controls. The chronically increased and maintained higher levels of aPWV suggests premature vascular ageing and increased cardiovascular risk in COPD patients. Although patients with COPD had increased aPWV, only CPP was independently associated with cerebral flow pulsatility, suggesting the utility of CPP to potentially indicate and monitor cerebrovascular changes throughout disease. The relationship between cerebral pulsatility and cerebral volumes measured by MRI suggests a potential role of MCAPI in cardiovascular risk prediction. However, further large-scale studies are needed to improve understanding of the systemic mechanisms underlying cardiovascular risks and their interaction with comorbidities to improve outcomes in COPD.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Healthcare Sciences
Date of First Compliant Deposit:	16 August 2021
Last Modified:	16 Aug 2021 15:11
URI:	https://orca.cardiff.ac.uk/id/eprint/143437

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