Recently, a video was released discussing how the theory of arterial acceleration is part of the ongoing scientific quest for a better understanding of cardiovascular physiology. This quest started with Galen in the 2nd century, is greatly furthered by Harvey in the 17th century as well as by various investigators at the end of the 19th century. The theory of acceleration adds to conceptual thinking about the role of the arterial system in cardiovascular physiology. It challenges a too simplistic view on arterial blood pressure.

 

Neuromon has prepared 6 presentations of 8 to 13 minutes explaining the theoretical background behind the model for cardiovascular simulation. This model was originally developed in Labview™ in collaboration with Annika de Goede from the TUTwente. It was subsequently translated to C# by Neuromon. After registration, the model can be downloaded from the web page.

The model of cardiovascular simulation should be seen as an illustration of theoretical concepts in cardiovascular physiology. It includes the CNS ischemic response, the theory of arterial acceleration and cardiovascular reflexes such as auto regulation, the baroceptosr reflex the chemoreceptor reflex and the Bainbridge reflex.

Incorporating different physiological responses into a single computer simulation helps to understand the complex interplay of all these responses combined. A computer simulation should be seen as an illustration of the theory. It is based upon simple mathematical rules that joined together become a system of high complexity. A model as this, however, can never live up to the complexity of cardiovascular physiology in real life.

The 6 presentations can be found on the web page for theoretical background.

Alternatively, a link to the first presentation can be found below.

Anticipating the release of the NMA module for Compumedics DWL QL software, Neuromon BV has released the so called NMA app for the iPhone.

This app intends to bridge the gap between middle cerebral artery flow velocity parameterisation and clinical interpretation. Basically, sys1, sys2, dias@560 and HR are converted to so-called Z-scores that correct for the effects of ageing. 

Based upon published observations the Z-scores are used for clinical interpretation. Of course, Neuromon BV cannot take the responsibility for clinical decision making and the NMA app should only be seen as support in the process. Treating physicians should always remain vigilant and not use information from the NMA alone to interpret the clinical condition of a patient. Nevertheless, the NMA module brings a new approach to patient assessment on the ICU based upon a new philosophy on cardiovascular physiology.

Find your NMA in the Appstore via this link NMA or alternatively by searching "NMA TCD".

 

   

 

Middle cerebral artery flow velocity decreases with age. When studying subjects with transcranial Doppler, these age-related changes should be taken into account. A recent paper by dr. A. Schaafsma promotes Z-scores as a way to correct for age. Z-scores express the distance in standard deviations to the middle cerebral artery flow velocity expected for age by linear regression.

       

A Z-score expresses how many standard deviations a given measurement is above (positive) or below (negative) the value expected for a given age. Z-scores for different parameters can be combined into a radar plot. An example is give to the right: data are provided for average Z-scores during hyperventilation (red), normoventilation (green) and CO2-retention (yellow).

A. Schaafsma, A new method for correcting middle cerebral artery flow velocity for age by calculating Z-scores. Journal of Neuroscience Methods. 307, 1–7 (2018).

In a joint effort DWL and Neuromon B.V. have recently made the new TCD parameters available for current and future DWL customers. In the latest QL software signal analysis based upon the new TCD parameters is optionally available. It can be acquired via the DWL distributors network. The new TCD parameters significantly enhance signal analysis and interpretation. Please refer to relevant literature.