title: Can intracranial pressure be measured non-invasively bedside using a two-depth Doppler-technique?
abstract: Measurement of intracranial pressure (ICP) is necessary in many neurological and neurosurgical diseases. To avoid lumbar puncture or intracranial ICP probes, non-invasive ICP techniques are becoming popular. A recently developed technology uses two-depth Doppler to compare arterial pulsations in the intra- and extra-cranial segments of the ophthalmic artery for non-invasive estimation of ICP. The aim of this study was to investigate how well non-invasively-measured ICP and invasively-measured cerebrospinal fluid (CSF) pressure correlate. We performed multiple measurements over a wide ICP span in eighteen elderly patients with communicating hydrocephalus. As a reference, an automatic CSF infusion apparatus was connected to the lumbar space. Ringer's solution was used to create elevation to pre-defined ICP levels. Bench tests of the infusion apparatus showed a random error (95 % CI) of less than ±0.9 mmHg and a systematic error of less than ±0.5 mmHg. Reliable Doppler signals were obtained in 13 (72 %) patients. An infusion test could not be performed in one patient. Thus, twelve patients and a total of 61 paired data points were studied. The correlation between invasive and non-invasive ICP measurements was good (R = 0.74), and the 95 % limits of agreements were -1.4 ± 8.8 mmHg. The within-patient correlation varied between 0.47 and 1.00. This non-invasive technique is promising, and these results encourage further development and evaluation before the method can be recommended for use in clinical practice.
authors.affiliation: Department of Clinical Neuroscience, Neurosurgery and Neurology, Umeå University, Umeå, 90185, Sweden. Lars-Owe.Koskinen@umu.se.
authors.forename: Lars-Owe D
authors.initials: LD
authors.lastname: Koskinen
authors.affiliation: Department of Clinical Neuroscience, Neurosurgery and Neurology, Umeå University, Umeå, 90185, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Malm
authors.affiliation: Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania.
authors.forename: Rolandas
authors.initials: R
authors.lastname: Zakelis
authors.affiliation: Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania.
authors.forename: Laimonas
authors.initials: L
authors.lastname: Bartusis
authors.affiliation: Health Telematics Science Institute, Kaunas University of Technology, Kaunas, Lithuania.
authors.forename: Arminas
authors.initials: A
authors.lastname: Ragauskas
authors.affiliation: Department Radiation Sciences - Biomedical Engineering, Umeå University, Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Eklund
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000000981:diagnostic imaging* / Q000503:physiopathology; D019586:Intracranial Hypertension; D007427:Intracranial Pressure; D016014:Linear Models; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods; D009880:Ophthalmic Artery / Q000000981:diagnostic imaging*; D000067716:Point-of-Care Testing; D012016:Reference Values; D015203:Reproducibility of Results; D018608:Ultrasonography, Doppler / Q000379:methods*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
keywords: Infusion test; Intracranial pressure; Non-invasive ICP; Ophthalmic artery; Transcranial-Doppler