A portable device for intensive care brain function monitoring with event-related potentials

Monitoring level of consciousness or depth of sedation is essential in modern intensive care units and emergency rooms. Current methods are based on spontaneous EEG providing only indirect information on the reactivity of the brain. Measurement of auditory event-related potentials (ERPs) has been shown to have additional potential for evaluation of the level of consciousness. Unfortunately, compact and easy-to-use devices are not commercially available. In this study a portable battery-powered device for clinical auditory ERP measurements was designed, constructed and validated. The device consists of a five-channel data logger and a 16-bit stereo audio stimulator. The signals are digitized with a 22-bit sigma-delta analogue-to-digital converter and stored to a PC Card hard disk. Prior to the in vivo application, the device was validated with extensive technical tests. Importantly, the RMS noise amplitude of the EEG channels was found to be less than 1 mivroV and the delivered auditory stimulus intensity corresponded accurately the settings (mean difference 0.2+/-0.5 dB). In addition to technical tests the device was successfully validated in vivo. To summarize, a novel portable instrument for measurement of auditory event-related potentials in intensive care environment is introduced.

[1]  S. Hillyard,et al.  Electrical Signs of Selective Attention in the Human Brain , 1973, Science.

[2]  Kara D. Federmeier,et al.  Handbook of Psychophysiology: Event-Related Brain Potentials: Methods, Theory, and Applications , 2007 .

[3]  Juhani Partanen,et al.  Processing of highly novel auditory events in children and adults: an event-related potential study , 2005, Neuroreport.

[4]  V. Jousmäki,et al.  Habituation of auditory N100 correlates with amygdaloid volumes and frontal functions in age-associated memory impairment , 1995, Physiology & Behavior.

[5]  M R Nuwer,et al.  IFCN recommended standards for long-latency auditory event-related potentials. Report of an IFCN committee. International Federation of Clinical Neurophysiology. , 1994, Electroencephalography and clinical neurophysiology.

[6]  R C Burgess,et al.  Event related potentials I , 1992, Clinical Neurophysiology.

[7]  Ilkka Korhonen,et al.  The effect of interruption to propofol sedation on auditory event-related potentials and electroencephalogram in intensive care patients , 2004, Critical care.

[8]  I. Tarkka,et al.  Augmentation of Auditory N1 in Children with Fragile X Syndrome , 2004, Brain Topography.

[9]  U Hegerl,et al.  Event-related potentials: Do they reflect central serotonergic neurotransmission and do they predict clinical response to serotonin agonists? , 2001 .

[10]  G. B. Young,et al.  EEG monitoring in the intensive care unit: pitfalls and caveats. , 1999, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[11]  Ilkka Korhonen,et al.  Assessment of postoperative sedation level with spectral EEG parameters , 2002, Clinical Neurophysiology.

[12]  E. Halgren,et al.  The intracranial topography of the P3 event-related potential elicited during auditory oddball. , 1990, Electroencephalography and clinical neurophysiology.

[13]  J. Partanen,et al.  Sevoflurane anaesthesia in children after induction of anaesthesia with midazolam and thiopental does not cause epileptiform EEG. , 2002, British journal of anaesthesia.

[14]  G. Comi,et al.  IFCN standards for digital recording of clinical EEG. International Federation of Clinical Neurophysiology. , 1998, Electroencephalography and clinical neurophysiology.

[15]  H. Nyquist,et al.  Certain Topics in Telegraph Transmission Theory , 1928, Transactions of the American Institute of Electrical Engineers.

[16]  Juhani Partanen,et al.  P3 amplitude and time-on-task effects in distractible adolescents , 2005, Clinical Neurophysiology.

[17]  P. Brodal.  The Central Nervous System , 1992 .

[18]  T. Picton,et al.  The N1 wave of the human electric and magnetic response to sound: a review and an analysis of the component structure. , 1987, Psychophysiology.

[19]  William H. Press,et al.  Numerical recipes in C. The art of scientific computing , 1987 .

[20]  Tim Williams.  EMC for product designers , 1996 .

[21]  J. Karhu,et al.  Dual cerebral processing of elementary auditory input in children , 1997, Neuroreport.

[22]  Margot J. Taylor,et al.  Guidelines for using human event-related potentials to study cognition: recording standards and publication criteria. , 2000, Psychophysiology.

[23]  Juhani Partanen,et al.  Selective attention event-related potential effects from auditory novel stimuli in children and adults , 2005, Clinical Neurophysiology.

[24]  Juhani Partanen,et al.  Evidence of auditory processing during postoperative propofol sedation , 2002, Clinical Neurophysiology.

[25]  K. Jordan,et al.  Continuous EEG monitoring in the neuroscience intensive care unit and emergency department. , 1999, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[26]  G. Adler,et al.  Influence of stimulus intensity on AEP components in the 80- to 200-millisecond latency range. , 1989, Audiology : official organ of the International Society of Audiology.

[27]  W. Press,et al.  Numerical Recipes: The Art of Scientific Computing , 1987 .

[28]  Ilkka Korhonen,et al.  N100 Auditory Potential and Electroencephalogram Discriminate Propofol-Induced Sedation Levels , 2003, Journal of Clinical Monitoring and Computing.

[29]  I Korhonen,et al.  Recovery of N100 component of auditory event-related potentials and EEG after cardiac arrest during propofol sedation. , 2005, British journal of anaesthesia.

[30]  Ilkka Korhonen,et al.  Measuring Depth of Sedation with Auditory Evoked Potentials During Controlled Infusion of Propofol and Remifentanil in Healthy Volunteers , 2004, Anesthesia and analgesia.

[31]  J. Schumacher,et al.  Chapter 27 – Anesthesia and Analgesia , 2006 .

[32]  J. Partanen,et al.  Event-related potentials to elementary auditory input in distractible adolescents , 2005, Clinical Neurophysiology.

[33]  У Отт Генри,et al.  Методы подавления шумов и помех в электронных системах. (Noise reduction techniques in electronic systems) , 1979 .

[34]  C. B. G. Campbell,et al.  The Central Nervous System , 1975 .