Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Medical Biophysics

Supervisor

Dr. Keith St Lawrence

2nd Supervisor

Dr. Sandrine de Ribaupierre

Joint Supervisor

Abstract

Post-hemorrhagic ventricular dilatation (PHVD) is highly predictive of mortality and morbidity among very low birth weight preterm infants. Impaired cerebral blood flow (CBF) due to elevated intracranial pressure (ICP) is believed to be a contributing factor. In this study, a hyperspectral near-infrared spectroscopy (NIRS) method of measuring CBF and the cerebral metabolic rate of oxygen (CMRO2) was used to investigate perfusion and metabolism changes in patients receiving a ventricular tap (VT) based on clinical signs of elevated ICP. To improve measurement accuracy, the spectral analysis was modified to account for compression of the cortical mantle caused by PHVD and the possible presence of blood breakdown products. From 9 patients (27 VTs), a significant increase in CBF was measured (15.6%) following VT (14.6 ± 4.2 to 16.9 ± 6.6 ml/100g/min), but no corresponding change in CMRO2 (1.02 ± .41 ml O2/100g/min) was observed. Post-VT CBF was in good agreement with a control group of 13 patients with patent ductus arteriosus and no major cerebral pathology (16.5 ± 7.7 ml/100g/min), while StO2 was significantly lower in these patients (58.9 ± 12.1 versus 70.5 ± 9.1% for controls). This study demonstrates that PHVD impedes CBF; however, no change in CMRO2 was observed.

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