Autoregulation monitoring and outcome prediction in neurocritical care patients: Does one index fit all?

Abstract

Indexes PRx and Mx have been formerly introduced to assess cerebral autoregulation and have been shown to be associated with 3-month clinical outcome. In a mixed cohort of neurocritical care patients, we retrospectively investigated the impact of selected clinical characteristics on this association. Forty-one patients (18–77 years) with severe traumatic (TBI, N = 20) and non-traumatic (N = 21) brain injuries were studied. Cerebral blood flow velocity, arterial blood pressure and intracranial pressure were repeatedly recorded during 1-h periods. Calculated PRx and Mx were correlated with 3-month clinical outcome score of modified Rankin Scale (mRS) in different subgroups with specific clinical characteristics. Both PRx and Mx correlated significantly with outcome (PRx: r = 0.38, p < 0.05; AUC = 0.64, n.s./Mx: r = 0.48, p < 0.005; AUC = 0.80, p < 0.005) in the overall group, and in patients with hemicraniectomy (N = 17; PRx: r = 0.73, p < 0.001; AUC = 0.89, p < 0.01/Mx: r = 0.69, p < 0.005; AUC = 0.87, p < 0.05). Mx, not PRx, correlated significantly with mRS in patients with heart failure (N = 17; r = 0.69, p < 0.005; AUC = 0.92, p < 0.005), and in non-traumatic patients (r = 0.49, p < 0.05; AUC = 0.79, p < 0.05). PRx, not Mx, correlated significantly with mRS in TBI patients (r = 0.63, p < 0.01; AUC = 0.89, p < 0.01). Both indexes did not correlate with mRS in diabetes patients (N = 15), PRx failed in hypocapnic patients (N = 26). Both PRx and Mx were significantly associated with 3-month clinical outcome, even in patients with hemicraniectomy. PRx was more appropriate for TBI patients, while Mx was better suited for non-traumatic patients and patients with heart failure. Prognostic values of indexes were affected by diabetes (both Mx and PRx) and hypocapnia (PRx only).

Comparative Study of Novel Noninvasive Cerebral Autoregulation Volumetric Reactivity Indices Reflected by Ultrasonic Speed and Attenuation as Dynamic Measurements in the Human Brain

“…On the other hand, Bland-Altman's direct comparison proved that both classifiers gave intact cerebral autoregulation values, as both the curves of VRx1 and VRx2 had outcomes from −1 to zero (see Figure 7a,b), which was intact autoregulation [15,28,29,[33][34][35][36][37]. As we already knew that we were using healthy subjects for the study, that guaranteed an intact outcome.…”

“…The speed and attenuation of ultrasound reflect the density of blood, brain tissue, and cerebrospinal fluid volumes inside an acoustic path. According to the database of the IT'IS (Information Technologies in Society) Foundation (Switzerland, 2019) [33], the values of ultrasound speed (± standard deviation) in blood, brain tissue, and cerebrospinal fluid were 1578.2 (± 11.3) m/s, 1546.3 (± 20.2) m/s, and 1505.5 (± 3.5) m/s, respectively. Ultrasonic time-of-flight technology measures the time of short ultrasound pulses transmitted through the human head with picosecond resolution and the attenuation of such pulses.…”

“…The ABP(t) slow wave reference signal was taken from a noninvasive ABP(t) Finapres Nova monitor. Negative values of both VRx(t) < 0 corresponded to intact CA status, and positive VRx(t) values > indicated CA impairment [15,28,29,[33][34][35][36][37]. Two-minute moving averages of both VRx(t) were used to obtain a temporal resolution of CA impairments that were at least two times better than those obtained with NIRS or Doppler CA monitors.…”

Transcranial Doppler Based Cerebrovascular Reactivity Indices in Adult Traumatic Brain Injury: A Scoping Review of Associations With Patient Oriented Outcomes

“…Once again, Mx seems to have the strongest body of evidence supporting its association with outcomes with studies consistently finding that a higher Mx was associated with poor or unfavourable outcome at follow up (Czosnyka et al, 1996;Czosnyka et al, 1997;Czosnyka et al, 1999;Czosnyka et al, 2000;Czosnyka et al, 2001;Czosnyka et al, 2002;Czosnyka et al, 2008;Lang et al, 2003a;Lewis et al, 2007;Lewis et al, 2012;Radolovich et al, 2011;Sorrentino et al, 2011;Budohoski et al, 2012a;Budohoski et al, 2012c;Liu et al, 2015;Schmidt et al, 2016a). When Mx was found to not be associated with outcomes, it was often attributed to small sample sizes (Schmidt et al, 2016b;Zeiler et al, 2017b). Those with a favourable outcome had a lower mean Mx (−0.06 ± 0.26 vs. 0.15 ± 0.31, p < 0.00002), lower mean ICP (17.0 ± 8.9 vs. 23.0 ± 13, p < 0.003), higher GCS on admission (6 vs. 4, p < 0.0018) Mx (r −0.2592, p < 0.0001), PRx (r 0.278, p < 0.0001), ICP (r −0.195, p < 0.01) and GCS (r −0.18, p < 0.014) were all correlated with 6-month GOS Thresholds of Mx (0.23) and PRx (0.31) were found by identifying where the Absolute left to right difference in Mx was correlated with Mx (mean left-right) (r 0.24, p < 0.025) Asymmetry was higher in those that died than survived (0.14 ± 0.18 vs. 0.08 ± 0.1, p 0.04) Mx was higher in those that died (0.13 ± 0.05 vs. −0.03 ± 0.05, p 0.002) By multiple regression analysis outcome was independently correlated with asymmetry of Mx (p < 0.0015) Hemispheric asymmetry in Mx was independently associated with outcome following TBI Single institution dataset Schmidt et al (2009) Primary: The assess if Mx/Mx_a were different during increases of CPP than during decreases of CPP Mx was significantly different during increases of CPP than during decreases of CPP (0.05 ± 0.49 vs. 0.14 ± 0.54, p < 0.005) Mx_a was not significantly different during increases in CPP compared to decreases in CPP Cerebrovascular reactivity, as measured by Mx, appears to be stronger during increases in CPP than during decreases in CPP During analysis, a large proportion of data was discarded with data from 53 out of 210 patients used in the study Schmidt et al (2012) Primary: To evaluate if cerebrovascular reactivity differs during increases in CPP as compared to decreases in CPP Cerebrovascular reactivity, as measured by Mx, was stronger during increases in CPP compared to decreases in CPP (0.06 ± 0.52 vs. 0.15 ± 0.55, p...…”

Reliability, reproducibility and validity of dynamic cerebral autoregulation in a large cohort with transient ischaemic attack or minor stroke

“…Dynamic CA in response to rapid BP changes can be estimated from direct physiological challenges or from resting-state fluctuations in BP, with previous studies showing a symmetry and a significant correlation between CA indices derived from the contralateral middle cerebral arteries (MCAs) ( Schmidt et al 2003 ). CA is impaired in severe traumatic brain injury ( Liu et al 2017 ; Czosnyka et al 2001 ; Schmidt et al 2016 ), intracerebral haemorrhage ( Lee et al 2017 ; Ma et al 2016 ; Oeinck et al 2013 ), subarachnoid haemorrhage ( Budohoski et al 2012 , 2013 ), and major ischaemic stroke ( Reinhard et al 2012 ; Chi et al 2018 ). However, its role in predicting the risk of recurrent events is unclear.…”