The solutions provided by Quantium Medical are widely used either as OEM for integration by monitor manufacturers, or as finished products created by the company.

With install bases in Europe, Asia, Latin America, and Middle East, we are proud of our global footprint.

Nonetheless, it’s not just about offering a proven solution! We live in an evolving world and technology needs to keep improving thanks to customer feedback, constant research, and a solid R&D team.

The success of our qCON / qNOX and Conox solutions is based on constant research through collaboration projects with different hospitals in Europe, US and Asia.

We are constantly reviewing our specs and looking to improve not only how our technology works, but also looking into how we can add more value to patient monitoring.

Recently one of our lead R&D persons (Carmen González Pijuan, PhD in Biomedical Engineering) concluded successfully a 3-year research project, allowing us to take our monitoring solutions to a next level.

Following is a summary of this research, for which Quantium medical has already filed a patent application: PCT/EP2018/064061.

Depth of anaesthesia monitoring integrating cerebral blood flow estimations

Cerebral blood flow (CBF) reflects the rate of delivery of arterial blood to the brain. Since no nutrients, oxygen or water can be stored in the cranial cavity due to space and pressure restrictions, a continuous perfusion of the brain is critical for survival. Anaesthetic procedures are known to affect cerebral haemodynamics, but CBF is only monitored in critical patients due, among others, to the lack of continuous and easy to use bedside monitors for this purpose.

Our research proposes a potential solution through bioelectrical impedance technology, also known as rheoencephalography (REG). The underlying hypothesis is that REG signals carry information on CBF that might be recovered by means of the application of advanced signal processing techniques, allowing us to track CBF alterations during anaesthetic procedures. 

The strength of Quantium Medical is its capacity to provide new indices by applying advanced mathematical models. Throughout this research a series of analysis techniques and monitoring solutions have been used to create a solid baseline analysis that has provided valuable conclusions.

The relationship between global haemodynamics, cerebral haemodynamics and EEG based parameters are analysed, looking for causal relationships among them. Interactions were detected during anaesthetic drug infusion and patient positioning, providing evidence of the coupling between haemodynamics and brain activity.

As mentioned, causal interactions between general haemodynamics, cerebral haemodynamics and brain activity have been studied. A first analysis along complete surgical procedures has been performed, followed by a breakdown of specific events such as patient positioning or drug infusion. Brain activity, represented by EEG related variables, showed a causal relationship with haemodynamics, suggesting that clinical decisions related to anaesthesia should integrate CBF measurements to preserve hemodynamic stability at a general and cerebral level.

During propofol general anaesthesia, both CBF and EEG signals suffer changes due to the induced loss of consciousness and depressed hemodynamic activity. Our research was aimed at analysing the causal relationships between both physiological signals during anaesthetic procedures.

Besides the direct effects of propofol concentration changes in all the physiological variables under study, the causal relationships among haemodynamics and EEG might also be affected by the administration of the hypnotic drug. Even though the detected interactions are similar to those during steady state anaesthesia, several differences can be appreciated. For instance, the occurrence of causal interactions from HR and MAP towards CBF PP, CBF lin and EEG are higher, suggesting that changes in HR caused by propofol are projected in CBF and EEG. Additionally, causal effects from CBF linked to HR and EEG are also more frequent under propofol infusion, while the interactions between MAP and HR have a lower occurrence. Overall, changing the propofol effect site concentration elicits a higher number of interactions from both cerebral and global haemodynamics towards EEG.

Figure 1: Sensor electrodes positioning on forehead for accurate REG measurement.

Conclusions

The causal relationships between REG signals and other physiological data were assessed to explore the adequacy and need for REG monitoring during surgery. Overall, considering all the surgical procedures, interactions between general haemodynamics, brain haemodynamics and electroencephalographic activity (EEG) were detected, confirming the hypothesis that CBF is linked to both the hemodynamic stability and the brain activity modulated by anaesthetic drugs. Additionally, specific events during the anaesthetic procedures were analysed as well, such as drug infusion, patient positioning and the administration of vasoactive drugs. In all those cases, causal interactions were detected, showing that decisions on drug dosages and patient positioning should be made considering both the hemodynamic stability and depth of anaesthesia simultaneously, since hemodynamic changes might induce brain activity levels to increase or decrease, and vice versa.

From a scientific perspective, the results of this research project justify a new opportunity for REG signals, since the application of advanced signal processing techniques has shown to be effective in tracking CBF information embedded in REG recordings. Moreover, the interaction among different physiological networks has been further assessed and quantified, contributing to the knowledge on the effects of anaesthetics in the brain and the mechanisms cooperating to achieve a successful and stable anaesthetic state. Considering the clinical benefits, CBF monitoring through REG could be extended to all kind of patients, even to those initially at low risk, making it possible to reduce the occurrence of adverse events that might sometimes have deleterious effects for patients.

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