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Increased risk of critical CBF levels in SAH patients with actual CPP below calculated optimal CPP
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurosurgery. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.ORCID iD: 0000-0002-3879-6476
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurosurgery. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.ORCID iD: 0000-0002-9826-1422
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurosurgery.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Neurosurgery.
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2017 (English)In: Acta Neurochirurgica, ISSN 0001-6268, E-ISSN 0942-0940, Vol. 159, no 6, 1065-1071 p.Article in journal (Refereed) Published
Abstract [en]

Background Cerebral pressure autoregulation can be quantified with the pressure reactivity index (PRx), based on the correlation between blood pressure and intracranial pressure. Using PRx optimal cerebral perfusion pressure (CPPopt) can be calculated, i.e., the level of CPP where autoregulation functions best. The relation between cerebral blood flow (CBF) and CPPopt has not been examined. The objective was to assess to which extent CPPopt can be calculated in SAH patients and to investigate CPPopt in relation to CBF.

Methods Retrospective study of prospectively collected data. CBF was measured bedside with Xenon-enhanced CT (Xe-CT). The difference between actual CPP and CPPopt was calculated (CPPa dagger). Correlations between CPPa dagger and CBF parameters were calculated with Spearman's rank order correlation coefficient (rho). Separate calculations were done using all patients (day 0-14 after onset) as well as in two subgroups (day 0-3 and day 4-14).

Results Eighty-two patients with 145 Xe-CT scans were studied. Automated calculation of CPPopt was possible in adjunct to 60% of the Xe-CT scans. Actual CPP < CPPopt was associated with higher numbers of low-flow regions (CBF < 10 ml/100 g/min) in both the early phase (day 0-3, n = 39, Spearman's rho = -0.38, p = 0.02) and late acute phase of the disease (day 4-14, n = 35, Spearman's rho = -0.39, p = 0.02). CPP level per se was not associated with CBF.

Conclusions Calculation of CPPopt is possible in a majority of patients with severe SAH. Actual CPP below CPPopt is associated with low CBF.

Place, publisher, year, edition, pages
2017. Vol. 159, no 6, 1065-1071 p.
Keyword [en]
cerebral blood flow, autoregulation, CPP, subarachnoid haemorrhage
National Category
Clinical Medicine
Research subject
Neurosurgery
Identifiers
URN: urn:nbn:se:uu:diva-294191DOI: 10.1007/s00701-017-3139-7ISI: 000401117700016PubMedID: 28361248OAI: oai:DiVA.org:uu-294191DiVA: diva2:972566
Available from: 2016-09-21 Created: 2016-05-18 Last updated: 2017-06-13Bibliographically approved
In thesis
1. Pressure autoregulation of cerebral blood flow in traumatic brain injury and aneurysmal subarachnoid hemorrhage
Open this publication in new window or tab >>Pressure autoregulation of cerebral blood flow in traumatic brain injury and aneurysmal subarachnoid hemorrhage
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The ability of the brain to keep a stable and adequate cerebral blood flow (CBF) independently of fluctuations in systemic blood pressure is referred to as cerebral pressure autoregulation (CPA). When the brain is injured by trauma or hemorrhage, this ability may be impaired, leaving the brain vulnerable to events of high or low blood pressure. The aims of this thesis were to study CPA in patients with severe traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH), the relation between CPA and other physiological parameters, and the influence of CPA on outcome. Four retrospective studies are included in the thesis. All patients were treated at the neurointensive care unit, Uppsala University hospital.

In paper I, 58 TBI patients were studied. In patients with impaired CPA, cerebral perfusion pressure between 50-60 mm Hg was associated with favorable outcome while CPP > 70 and >80 mm Hg was associated with unfavorable outcome. In patients with intact CPA there was no association between CPP and outcome.

In paper II, 107 TBI patients were studied. High CPP was associated with unfavorable outcome in patients with focal injuries. In patients with diffuse injury and impaired CPA, CPP > 70 mm Hg was associated with favorable outcome.

In paper III, 47 SAH patients were studied. CBF was measured bedside with Xenon-enhance CT (Xe-CT). Patients with impaired CPA had lower CBF, both in the early (day 0-3) and late (day 4-14) acute phase of the disease.

In paper IV, 64 SAH patients were studied. Optimal CPP (CPPopt) was calculated automatically as the level of CPP where CPA works best for the patient, i.e., where PRx is lowest. Patients with actual CPP below their calculated optimum had higher amounts of low-flow regions (CBF < 10 ml/100g/min).

The findings in this thesis emphasize the importance of taking CPA into account in the management of TBI and SAH patients, and suggest that treatment should be individualized depending on status of autoregulation. PRx and CPPopt may be used bedside to guide management according to status of autoregulation. In the future CPA-guided management should be tested in prospective studies

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 62 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1257
Keyword
cerebral blood flow, autoregulation, traumatic brain injury, subarachnoid hemorrhage
National Category
Neurosciences
Research subject
Neurosurgery
Identifiers
urn:nbn:se:uu:diva-294190 (URN)978-91-554-9703-3 (ISBN)
Public defence
2016-11-17, Enghoffsalen, Ing 50 bv, Akademiska sjukhuset, 75185, Uppsala, 09:00 (Swedish)
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Supervisors
Available from: 2016-10-27 Created: 2016-05-18 Last updated: 2016-11-02

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Johnson, UlfEngquist, HenrikLewén, AndersNilsson, PelleRonne-Engström, ElisabethRostami, ElhamEnblad, Per

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