Y. Hamarat doctoral dissertation “Investigation of transorbital doppler technology for non-invasive intracranial pressure and cerebral autoregulation monitoring” defence

Thesis Defense

Author, Institution: Yasin Hamarat, Kaunas University of Technology

Science area, field of science: Technological Sciences, Measurement Engineering, T010

Scientific Supervisor: prof. dr. Arminas Ragauskas

Dissertation Defence Board of Measurement Engineering Science Field:
Prof. Dr. Renaldas Raišutis (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010), chairman
Prof. Dr. Bayram Yilmaz (Yeditepe University, Turkey, Medical and Health Sciences, Medicine – M001)
Prof. Dr. Vaidotas Marozas (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010)
Prof. Dr. Kęstutis Ručinskas (Vilnius University, Medical and Health Sciences, Medicine – M001)
Assoc. Prof. Dr. Reimondas Šliteris (Kaunas University of Technology, Technological Sciences, Measurement Engineering, T010)

The doctoral dissertation is available at the library of Kaunas University of Technology (K. Donelaičio St. 20, Kaunas, Lithuania)


Intracranial pressure (ICP) is the cerebrospinal fluid pressure inside the cranium and in clinical practice is usually measured in millimeters of mercury. Definition of ICP – it is the pressure around the brain caused by cerebrospinal fluid or blood. Measuring of ICP is clinically important in neurological and neurosurgical diseases. Even secondary brain injuries that were caused by elevated ICP take place in minutes. An ICP monitor is needed to diagnose elevated ICP since clinical evaluation alone is not enough to determine raised ICP. Therefore, an ICP monitor is recommended for patients when the risk of intracranial hypertension and abnormal admission head computed tomography (CT) exists. In dissertation, the objective is to investigate the possibility to monitor intracranial pressure (ICP) continuously and non-invasively by adapting the non-invasive ICP snap-shot measurement algorithm and the monitoring device. The non-invasive ICP monitoring results were compared with the invasive Codman microsensor readings on TBI patients. A total of 1928 paired data points of invasive (ICPinv) and non-invasive ICP (ICPnon-inv) monitoring methods were collected and extreme data points of measured differences between ICPinv and ICPnon-inv are –3.94 and 4.68 mmHg (95%CI = –2.55 to 2.72). The total mean and SD are 0.086±1.34 mmHg and correlation is 0.94 in this pilot study. The accuracy, precision, sensitivity and specificity for the non-invasive ICP monitoring were found to be 0.99 (95%CI = 0.93 to 0.94), 0.94 (95%CI = 0.93 to 0.94), 0.81 (95%CI = 0.78 to 0.84) and 0.91 (95% CI = 0.90 to 0.93), respectively. The significance of dissertation is that the novel non-invasive ICP monitoring method using the two-depth transcranial Doppler showed that the OA is a natural pressure sensor and it is possible to monitor the ICP for a 1-hour time period without recalibration.


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