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Evaluating Indices of Delayed Cerebral Ischemia and Poor Outcomes after Subarachnoid Hemorrhage: The Role of Cerebral Perfusion Pressure in Disease Pathogenesis

Yousef, Khalil M (2013) Evaluating Indices of Delayed Cerebral Ischemia and Poor Outcomes after Subarachnoid Hemorrhage: The Role of Cerebral Perfusion Pressure in Disease Pathogenesis. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Background and Purpose: Delayed cerebral ischemia (DCI) and Hunt and Hess (HH) grade are known risk factors for poor outcomes after aneurysmal subarachnoid hemorrhage (aSAH). DCI is often attributed to focal perfusion deficit (vasospasm/infarction). Global perfusion deficit (e.g. inadequate cerebral perfusion pressure (CPP)) can impair cerebral blood flow (CBF). The relationship between CPP and DCI remains unclear. Further, the exact mechanism of how HH grade relates to poor outcomes is uncertain. This study aimed to describe the temporal profiles of CPP change and to investigate the relationship between CPP, DCI, HH, and post-aSAH outcomes. Method: DCI was defined as clinical deterioration due to impaired CBF. Growth curve analysis was used to examine temporal profiles of CPP change. Logistic regression was utilized to examine the association between DCI and percentages of CPP values >110, >100, <70, and <60 mmHg. The associations between minimum CPP (measured 12 hours prior to DCI), DCI, and DCI onset, were tested using logistic regression and accelerated failure time model. The mediation effect of DCI on the relationship between HH and outcomes was tested using bootstrap confidence interval. Outcomes were assessed at 3 and 12 months and included: mortality, neuropsychological, functional, and physical outcomes. Results: There was a significant linear increase in CPP over time (β =0.06, SE=0.006, p<0.001). The covariance (-0.52) between the initial CPP and the linear change parameter was negative indicating that subjects with high CPP had a slower rate of increase and those with low CPP had a faster rate (p<0.001). For every 10% increase in the proportion of CPP>100 or >110 mmHg, the odds of DCI increased by 1.21 and 1.43, respectively. For every 10 mmHg increase in CPP, the odds of DCI increased by 2.78 (95%CI 2.00-3.87). High CPP was associated with earlier onset of DCI (p<.001). DCI did not mediate the relationship between HH and outcomes. Conclusions: When used prophylactically, induced hypertension contributes to higher CPP values. Based on the CPP trends/correlations observed, induced hypertension may not confer expected benefits in patients with aSAH. Findings raise concerns about safety of induced hypertension and the need for determining limits for hypertension, which current guidelines lack.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Yousef, Khalil M
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee MemberBalzer,
Committee MemberBender, Catherine M.cbe100@pitt.eduCBE100
Committee MemberHoffman, Leslie Alhof@pitt.eduLHOF
Committee MemberPoloyac, Samuel Mpoloyac@pitt.eduPOLOYAC
Committee MemberYe, FeifeiFeifeiye@pitt.eduFEIFEIYE
Committee ChairSherwood, Paula Rprs11@pitt.eduPRS11
Date: 12 July 2013
Date Type: Publication
Defense Date: 5 June 2013
Approval Date: 12 July 2013
Submission Date: 6 July 2013
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 163
Institution: University of Pittsburgh
Schools and Programs: School of Nursing > Nursing
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Subarachnoid hemorrhage, Cerebral perfusion pressure, Delayed cerebral ischemia, induced hypertension
Date Deposited: 12 Jul 2013 21:14
Last Modified: 15 Nov 2016 14:14


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