John van Geest Centre for Brain Repair

School of Clinical Medicine



In this section


Peter Smielewski

  • Senior research associate at the Department of Clinical Neurosciences

    Peter Smielewski

  • MSc in Electronic Engineering at Warsaw University, Poland, followed by a PhD at the Department of Neurosurgery at Cambridge University ( Non invasive assessment of cerebral autoregulation)
  • Current research focuses on continuous monitoring of cerebrovascular dynamics in critical care patients, and in particular in traumatic brain injury
  • More than 160 publications in peer-reviewed journals and is the creator of a specialized research software ICM+ that provides real-time bed side monitor data analysis (
  • This pioneering software gathers data and produces real time trends of derived parameters defined using user-configurable signal processing formulae.  By means of a variety of inbuilt statistical and evidence based libraries the complex output can be summarized and presented in a concise fashion to medical staff and be used effectively in clinical scenarios.  ICM + was licensed by Cambridge University in 1994 and since then has become an integral part of intensive care monitoring in over 50 clinical research centres worldwide providing an invaluable platform for multi-centre collaborations in brain monitoring.
  • Also an expert (4th Dan – 4th degree black belt) in Taekwondo, a Korean martial art, and has been the chief instructor of the Cambridge University Taekwondo club since 1998


Current research

Cerebral autoregulation  (CA) provides haemodynamic reserve to cope with physiological insults and is an important neuroprotective mechanism. CA may be variably impaired following head injury and intracranial haemorrhage. Significant advances in TBI outcome have been achieved over the last 20 years by basing the management of systemic and cerebrovascular physiology on targets derived from population studies. However, this approach takes no account of interpatient heterogeneity as reflected by varying degrees of autoregulatory reserve in different patients. Cerebrovascular dysautoregulation impairs the brain’s ability to withstand minor physiological perturbations (modest hypotension, raised ICP, hypoxia and metabolic crises including ‘cortical spreading depression’ and fits) and hence is a determinant of outcome. However, CA is never disturbed nor fully functional forever, its status may fluctuate in time according to many factors, as cerebral perfusion pressure (CPP), arterial concentration of CO2, intracranial pressure (ICP), level of anesthesia, etc. Therefore, methods of continuous measurement of CA could facilitate potential, individualised, pro-CA treatments, as means of reducing the brain’s vulnerability to physiological insults. This may ensure that physiology is held within limits that can be tolerated even by compromised cerebrovascular physiology.

My current research is focused on methodologies of continuous monitoring of cerebral arterial blood and cerebral fluid dynamics. It involves development and optimalisation of mathematical models/algorithms for analysis of physiological waveforms collected from bed-side monitors, implementation of those methods into plugins for our ICM+ software, and subsequent clinical validation at the bed-side.


Thanks to our ICM+ project, I have developed an extensive network of high profile collaborators worldwide. This has resulted in a number of common projects and publications. I also regularly review manuscripts for Biomedical Engineering, Neurosurgical and Critical Care journals. I have also recently participated in a review panel for NASA assessing grant proposals for one of their space mission crew health project.

Key publications

Smielewski P, Czosnyka Z, Kasprowicz M, Pickard JD, Czosnyka M. ICM+: a versatile software for assessment of CSF dynamics. Acta Neurochir Suppl. 2012;114:75-9

Smielewski P, Lavinio A, Timofeev I, Radolovich D, Perkes I, Pickard JD,Czosnyka M. ICM+, a flexible platform for investigations of cerebrospinal dynamics in clinical practice. Acta Neurochir Suppl. 2008;102:145-51.

Smielewski P, Czosnyka M, Steiner L, Belestri M, Piechnik S, Pickard JD. ICM+: software for on-line analysis of bedside monitoring data after severe head trauma. Acta Neurochir Suppl. 2005;95:43-9.

Smielewski P, Coles JP, Fryer TD, Minhas PS, Menon DK, Pickard JD. Integrated image analysis solutions for PET datasets in damaged brain. J Clin Monit Comput. 2002 Dec;17(7-8):427-40.

Smielewski P, Czosnyka M, Pickard JD, Kirkpatrick P. Assessment of cerebrovascular reactivity in patients with carotid artery disease using near-infrared spectroscopy. Acta Neurochir Suppl. 1998;71:263-5.

Smielewski P, Czosnyka M, Kirkpatrick P, Pickard JD. Evaluation of the transient hyperemic response test in head-injured patients. J Neurosurg. 1997 May;86(5):773-8.

Smielewski P, Czosnyka M, Zabolotny W, Kirkpatrick P, Richards H, Pickard JD. A computing system for the clinical and experimental investigation of cerebrovascular reactivity. Int J Clin Monit Comput. 1997 Aug;14(3):185-98.

Smielewski P, Czosnyka M, Kirkpatrick P, McEroy H, Rutkowska H, Pickard JD. Assessment of cerebral autoregulation using carotid artery compression. Stroke. 1996 Dec;27(12):2197-203.

Aries MJ, Budohoski KP, Smielewski PS, Czosnyka M. Real availability of current devices in traumatic brain injury management. Crit Care Med. 2012 Nov;40(11):3117

Brady KM, Easley RB, Kibler K, Kaczka DW, Andropoulos D, Fraser CD 3rd, Smielewski P, Czosnyka M, Adams GJ, Rhee CJ, Rusin CG. Positive end-expiratory pressure oscillation facilitates brain vascular reactivity monitoring. J Appl Physiol. 2012 Nov;113(9):1362-8

Brady K, Joshi B, Zweifel C, Smielewski P, Czosnyka M, Easley RB, Hogue CW Jr. Real-time continuous monitoring of cerebral blood flow autoregulation using near-infrared spectroscopy in patients undergoing cardiopulmonary bypass. Stroke. 2010 Sep;41(9):1951-6.

Brady KM, Mytar JO, Kibler KK, Hogue CW Jr, Lee JK, Czosnyka M, Smielewski P, Easley RB. Noninvasive autoregulation monitoring with and without intracranial pressure in the naive piglet brain. Anesth Analg. 2010 Jul;111(1):191-5

Joshi B, Brady K, Lee J, Easley B, Panigrahi R, Smielewski P, Czosnyka M, Hogue CW Jr. Impaired autoregulation of cerebral blood flow during rewarming from hypothermic cardiopulmonary bypass and its potential association with stroke. Anesth Analg. 2010 Feb 1;110(2):321-8.

Brady KM, Shaffner DH, Lee JK, Easley RB, Smielewski P, Czosnyka M, Jallo GI, Guerguerian AM. Continuous monitoring of cerebrovascular pressure reactivity after traumatic brain injury in children. Pediatrics. 2009 Dec;124(6):e1205-12.

Lee JK, Kibler KK, Benni PB, Easley RB, Czosnyka M, Smielewski P, Koehler RC, Shaffner DH, Brady KM. Cerebrovascular reactivity measured by near-infrared spectroscopy. Stroke. 2009 May;40(5):1820-6.

Pfister D, Siegemund M, Dell-Kuster S, Smielewski P, RÃegg S, Strebel SP, Marsch SC, Pargger H, Steiner LA. Cerebral perfusion in sepsis-associated delirium. Crit Care. 2008;12(3):R63.

Czosnyka M, Smielewski P at al. An assessment of dynamic autoregulation from spontaneous fluctuations of cerebral blood flow velocity: a comparison of two models, index of autoregulation and mean flow index. Anesth Analg. 2008 Jan;106(1):234-9,

Brady KM, Lee JK, Kibler KK, Smielewski P, Czosnyka M, Easley RB, Koehler RC, Shaffner DH. Continuous time-domain analysis of cerebrovascular autoregulation using near-infrared spectroscopy. Stroke. 2007 Oct;38(10):2818-25.

Czosnyka M, Smielewski P,at al. A synopsis of brain pressures: which? when? are they all useful? Neurol Res. 2007 Oct;29(7):672-9. Review.

Czosnyka M, Smielewski P at al Intracranial pressure: more than a number. Neurosurg Focus. 2007 May 15;22(5):E10.

Lewis PM, Smielewski P at al Slow oscillations in middle cerebral artery cerebral blood flow velocity and aging. Neurol Res. 2007 Apr;29(3):260-3.

Eklund A, Smielewski P, Chambers I, Alperin N, Malm J, Czosnyka M, Marmarou A. Assessment of cerebrospinal fluid outflow resistance. Med Biol Eng Comput. 2007 Aug;45(8):719-35.

Lavinio A, Schmidt EA, Haubrich C, Smielewski P, Pickard JD, Czosnyka M. Noninvasive evaluation of dynamic cerebrovascular autoregulation using Finapres plethysmograph and transcranial Doppler. Stroke. 2007 Feb;38(2):402-4



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