Non-Invasive Brain Monitoring methodologies

Non-invasive indices are mainly based on TCD and NIRS monitoring. Multi-parametric TCD (in conjunction with arterial blood pressure) may include: autoregulation indices, non-invasive ICP and CPP, critical closing pressure, and the cerebrovascular time constant (TAU). NIRS is ideal for long-term, non-invasive monitoring of cerebral autoregulation.

Non-Invasive Intracranial Pressure Monitoring

Non-Invasive Intracranial Pressure analysis using ICM+

Intracranial pressure (ICP) is an important monitoring modality in the clinical management of several neurological diseases carrying the risk of fatal intracranial hypertension. However, this parameter is not always considered due to its invasive method of assessment. In this scenario, a non-invasive estimation of ICP (nICP) may be essential, and it has become a Holy Grail in Clinical Neurosciences.

Transcranial Doppler Assessment of Cerebral Autoregulation

Cerebral autoregulation is the ability of the brain to maintain a relatively constant blood flow during changes in cerebral perfusion pressure (CPP) or arterial blood pressure (ABP). Time trends of indices of cerebral autoregulation can be calculated from spontaneous fluctuations of CPP or ABP and cerebral blood flow velocity (FV).

Transcranial Doppler Assessment of Cerebral Haemodynamics

Various hydrodynamic models have been introduced in order to simulate cerebral haemodynamics. The identification of hydrodynamic models requires an array of signals as input, with the most common of them being arterial blood pressure, intracranial pressure, and cerebral blood flow velocity. Based on these signals, physiological parameters like cerebrovascular resistance and compliances of the cerebrovascular bed and cerebrospinal fluid space can be explored and experimented with. In addition, other secondary model-based indices describing cerebrovascular dynamics have been introduced, like the cerebral arterial time constant or critical closing pressure. All of these parameters can be calculated using ICM+.

Near-Infrared Spectroscopy

Near-infrared spectroscopy (NIRS) has gained recognition in monitoring various organs, including the central nervous system. Research on NIRS has demonstrated the possibility of using it for quantifying cerebral blood flow and cerebral blood volume, making NIRS technology more appealing for real-time monitoring, in particular in the acute care setting. The most common applications of NIRS for cerebral monitoring include subarachnoid haemorrhage, TBI, carotid endarterectomy, cardiac surgery, as well as liver transplantation. ICM+ allows the continuous monitoring of NIRS parameters in the context of multimodal brain monitoring.