Temporal Neurophysiological Dynamics in Traumatic Brain Injury: Role of Pressure Reactivity and Optimal Cerebral Perfusion Pressure for Predicting Outcome

Abstract

Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and the pressure reactivity index (PRx) have been shown to correlate with outcome after traumatic brain injury (TBI), but their temporal evolution is less studied. Optimal CPP (CPPopt; i.e., the CPP with the lowest [optimal] PRx value) has been proposed as a dynamic, individualized CPP target. Our aim was to map the temporal course of these parameters and their relation to outcome, in particular the extent and impact of CPP insults based both on fixed CPP thresholds and on divergence from CPPopt. Data from 362 TBI patients with ICP-monitoring treated at the neurointensive care unit of

Intracranial pressure variability: relation to clinical outcome, intracranial pressure–volume index, cerebrovascular reactivity and blood pressure variability

“…We have also found that ICPV defined as the absolute deviation from the mean value for 4 h was significantly higher for those with favorable compared to unfavorable outcome [5].…”

“…A previous study found that the pressure reactivity index was best evaluated in the frequency range with oscillations with periods from 55 to 15 s (PRx55-15) [5,12]. Similarly, ICP AMP 55-15 was an independent predictor of outcome, but ICPV-30m was a slightly stronger outcome predictor (Table 3).…”

“…3. As day 2 to 5 was the most sensitive time interval for the ICPV measures for outcome prediction [5], mean values for this 96-h-period were calculated of ICP, RAP, CPP, PRx, PRx55-15, ART Amp 55-15, BPV-30m, BPV-4h, ICP Amp 55-15, ICPV-30m and ICPV-4h in the Odin software. We also calculated the good monitoring time (GMT) % day 2 to 5 of CPP in the optimal range 60 to 70 mmHg according to the Brain Trauma foundation [16] and ICP > 20 mmHg.…”

“…PRx, which originally was described by Czosnyka et al, was calculated as a moving 5-min correlation of 10 s averages of ICP and MAP [11]. We also used a variant of PRx, PRx55-15, that was calculated in a similar way as PRx, but with a bandpass filter limiting the analysis to oscillations with periods from 55 to 15 s [5,12].…”

Arterial Oxygenation in Traumatic Brain Injury—Relation to Cerebral Energy Metabolism, Autoregulation, and Clinical Outcome

“…30 Pressure reactivity index, traditionally calculated as the 5-minute correlation of 10-second averages of ICP and MAP, 31 was used in combination with a bandpass filter, limiting the analysis to oscillations with periods of 15 to 55 seconds (PRx55-15). 32,33 For MD, we used the 71 High Cut-Off Brain Microdialysis Catheter with a membrane length of 10 mm and a membrane cutoff of 100 kDa (M Dialysis). The MD catheter was placed in normal-appearing brain tissue in the right frontal lobe, adjacent to the ICP monitor.…”