PD Dr. med. Emanuela Keller

 

Main Goals, Keywords

1. Development of New Methods for Measurement of Cerebral Blood Flow and Oxygenation. 2. Examination of the Inflammatory Response after Subarachnoid Hemorrhage. Therapeutic Hypothermia in Patients after Subarachnoid Hemorrhage. 3. Wireless Body Area Network for Patient Monitoring in Neurointensive Care Medicine.

Group Members

1 professor, 1 senior research fellow, 1 postdoctoral fellow, PhD and MD students

Previous and Current Research

1. Cerebral blood flow measurement

Our own clinical experiences in treatment of patients with severe stroke and subarachnoid hemorrhage showed that the available methods to monitor cerebral hemodynamics and oxygenation are insufficient with regard to detection of secondary ischemic events. The established methods for bedside monitoring of cerebral blood flow (CBF) and cerebral oxygenation are difficult to perform clinically, involve radioactive radiation, are invasive or require that the patient be transported, thus involving a potentially high risk. Our research projects, realized in 5 parts over a period of 8 years, allowed the development and implementation of a new technique to monitor regional cerebral hemodynamics. We could demonstrate, that the new methodology on the basis of near infrared spectroscopy (NIRS) and indocyanine green (ICG) dye dilution is a valid noninvasive method which for the first time facilitates serial bedside CBF measurements in the intensive care unit (ICU) environment providing data within minutes at the bedside.

2. Inflammatory response

Cerebral arterial vasospasm (CVS) occurs in up o 67% of patients following subarachnoid hemorrhage (SAH) and is symptomatic in 32%. Despite standard treatment with nimodipine and triple H therapy only 51% of patients with delayed ischemic deficits (DID) due to CVS make a good neurological recovery. Numerous animal studies described inflammatory changes in SAH in relation to the development of CVS. In experimental studies it could be demonstrated that hypothermia may attenuate the inflammatory response after SAH. Furthermore it could be shown, that monitoring of CBF may allow identifying patients with SAH with increased risk for ischemic complication. Since recently a new technique with indocyanine green dye dilution and NIRS is available, allowing CBF-measurements repetitively within minutes at the bedside on the intensive care unit. In own clinical pilot studies new neuroprotective treatment strategies like hypothermia and barbiturate coma has been successfully applied in patients after severe SAH and refractory CVS. The purpose of the present studies are therefore: To identify a characteristic pattern of inflammatory response and specific changes in cerebral hemodynamics as risk factors to develop CVS after SAH and to document the treatment effects of mild systemic hypothermia (33°C) as a neuroprotective treatment in patients with refractory CVS.

Future Projects

We will continue our efforts with optimisation and validation of the NIRS ICG dye dilution technique for CBF monitoring. Effects of hypothermia and barbiturate coma on the inflammatory response will be examined. A proposal for the sixth framework programme (Euresearch) is under preparation with the project “Wireless Body Area Network for Patient Monitoring in the Neurointensive Care Medicine”.

Techniques and Equipment

NIRS machine prototype for CBF measurement. Special equipments for neuromonitoring.

Selected Publications

• Muroi C, Hugelshofer M, Seule M, Tastan I, Fujioka M, Mishima K, Keller E. Correlation among systemic inflammatory parameter, occurrence of delayed neurological deficits, and outcome after aneurysmal subarachnoid hemorrhage. Neurosurgery. 2013 Mar;72(3):367-75; discussion 375. doi: 10.1227/NEU.0b013e31828048ce.
• Muroi C, Seule M, Sikorski C, Dent W, Keller E. Systemic interleukin-6 levels reflect illness course and prognosis of patients with spontaneous nonaneurysmal subarachnoid hemorrhage. Acta Neurochir Suppl. 2013;115:77-80.
• Seule M, Muroi C, Sikorski C, Keller E. Monitoring of cerebral hemodynamics and oxygenation to detect delayed ischemic neurological deficit after aneurysmal subarachnoid hemorrhage. Acta Neurochir Suppl. 2013;115:57-61.
• Muroi C, Burkhardt JK, Hugelshofer M, Seule M, Mishima K, Keller E. Magnesium and the inflammatory response: potential pathophysiological implications in the management of patients with aneurysmal subarachnoid hemorrhage? Magnes Res. 2012 Jul;25(2):64-71.

URL

http://www.zkf.uzh.ch/ResearchGroups/AlphabeticOrder/Keller.html