Effect of artifacts upon the pressure reactivity index

Abstract

The pressure reactivity index (PRx) is a parameter for the assessment of cerebrovascular autoregulation, but its calculation is affected by artifacts in the source biosignals—intracranial pressure (ICP) and arterial blood pressure. We sought to describe the most common short-duration artifacts and their effect on the PRx. A retrospective analysis of 935 h of multimodal monitoring data was conducted, and five types of artifacts, characterized by their shape, duration, and amplitude, were identified: rectangular, fast impulse, isoline drift, saw tooth, and constant ICP value. Subsequently, all types of artifacts were mathematically modeled and inserted into undisturbed segments of biosignals. Fast impulse, the most common artifact, did not alter the PRx index significantly when inserted into one or both signals. Artifacts present in one signal exceeded the threshold PRx in less than 5% of samples, except for isoline drift. Compared to that, the shortest rectangular artifact inserted into both signals changed PRx to a value above the set threshold in 55.4% of cases. Our analysis shows that the effect of individual artifacts on the PRx index is variable, depending on their occurrence in one or both signals, duration, and shape. This different effect suggests that potentially not all artifacts need to be removed.

The pressure reactivity index as a measure of cerebral autoregulation and its application in traumatic brain injury management

“…It is important to recognize that ICP and MAP data may contain random and aberrant elements, commonly referred to as ‘noise’ in the context of data analysis. 59 This data artifact may make the derivation of PRx less reliable and requires careful consideration when interpreting automated calculation of CPPopt. 60 CPPopt derivation is also limited by the range of CPPs that the patient experiences during the preceding hours.…”

Continuous monitoring of the lower limit of reactivity in traumatic brain injury patients: understanding what is feasible

“…The nature of variability in ABP and ICP must also be considered carefully as pointed out by Ayasse et al It is not really relevant whether the short-term variability in ABP is entirely internally driven (slow waves) or externally induced as long as the trigger does not impact ICP independently, violating implied causality. There are indeed episodes where the latter is true (suctioning events, position changes) which should be ideally eliminated from the data stream, along with other ABP and ICP artefacts [ 6 ], prior to calculation of PRx. However, when examined over 30–60 min or longer period of time, most of the artefactual effects would normally have limited influence on the average values.…”

Evaluation of Morlet Wavelet Analysis for Artifact Detection in Low-Frequency Commercial Near-Infrared Spectroscopy Systems

“…This approach relies upon a continuous stream of multi-modal data recorded at the bed side [ 1 , 3 , 6 , 7 ]. Bedside monitoring induces various artifacts into data streams, like device disruption, patient motion, and loss of signal quality [ 8 , 9 , 10 , 11 ]. The manual removal of artifacts requires personnel with an understanding of the bio-signal, is time consuming, is riddled with opportunity for human error, and has an associated time lag, all of which impedes the ability of clinicians to use the data in real time [ 3 , 10 ].…”

“…Bedside monitoring induces various artifacts into data streams, like device disruption, patient motion, and loss of signal quality [ 8 , 9 , 10 , 11 ]. The manual removal of artifacts requires personnel with an understanding of the bio-signal, is time consuming, is riddled with opportunity for human error, and has an associated time lag, all of which impedes the ability of clinicians to use the data in real time [ 3 , 10 ]. This necessitates a semi-/fully autonomous method of artifact clearing for multi-modal high-frequency data streams [ 3 , 10 , 12 , 13 , 14 ].…”