ICP, PRx, CPP, and ∆CPPopt in pediatric traumatic brain injury: the combined effect of insult intensity and duration on outcome

Abstract

Purpose The aim was to investigate the combined effect of insult intensity and duration, regarding intracranial pressure (ICP), pressure reactivity index (PRx), cerebral perfusion pressure (CPP), and optimal CPP (CPPopt), on clinical outcome in pediatric traumatic brain injury (TBI). Method This observational study included 61 pediatric patients with severe TBI, treated at the Uppsala University Hospital, between 2007 and 2018, with at least 12 h of ICP data the first 10 days post-injury. ICP, PRx, CPP, and ∆CPPopt (actual CPP-CPPopt) insults were visualized as 2-dimensional plots to illustrate the combined effect of insult intensity and duration on neurological recovery. Results This cohort was mostly adolescent pediatric TBI patients with a median age at 15 (interquartile range 12–16) years. For ICP, brief episodes (minutes) above 25 mmHg and slightly longer episodes (20 min) of ICP 20–25 mmHg correlated with unfavorable outcome. For PRx, brief episodes above 0.25 as well as slightly lower values (around 0) for longer periods of time (30 min) were associated with unfavorable outcome. For CPP, there was a transition from favorable to unfavorable outcome for CPP below 50 mmHg. There was no association between high CPP and outcome. For ∆CPPopt, there was a transition from favorable to unfavorable outcome when ∆CPPopt went below −10 mmHg. No association was found for positive ∆CPPopt values and outcome. Conclusions This visualization method illustrated the combined effect of insult intensity and duration in relation to outcome in severe pediatric TBI, supporting previous notions to avoid high ICP and low CPP for longer episodes of time. In addition, higher PRx for longer episodes of time and CPP below CPPopt more than −10 mmHg were associated with worse outcome, indicating a potential role for autoregulatory-oriented management in pediatric TBI.

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

“…131 Additionally, ICP is not a dichotomous parameter, and both the magnitude and duration of ICP elevations are associated with worse outcomes (pressure-time burden). 124,125,132,133 Güiza and colleagues demonstrated that children suffer injury at lower ICP burdens than adults and that cerebral autoregulation (CA) status is an important determinant of ICP tolerance. 124 While awaiting further prospective studies that could inform modifications of current guidelines, clinicians should consider age, and possibly autoregulation status, when establishing ICP/CPP goals.…”

“…[136][137][138] It increases vulnerability to secondary insults and is independently associated with worse outcomes. 132,[139][140][141][142][143][144][145][146][147] The most studied CA assessment method is the pressure reactivity index (PRx), which uses spontaneous variations in mean arterial pressure (MAP) to calculate a moving correlation coefficient (À1 to þ1) between ICP and MAP. 144 With intact CA, PRx should be zero or negative.…”

“…Positive values indicate pressure passive behavior, and PRx > 0.25 is associated with mortality. 132,140,145,146 Knowledge of CA status may be important for clinical management, although currently there is no gold standard test for its assessment. Patients with impaired CA seem to be less tolerant of high ICP and low CPP 124 and less likely to benefit from augmented MAP to achieve CPP goals, as it could further increase ICP.…”

“…CPP less than the calculated CPPopt may be associated with unfavorable outcomes. 132,143,[149][150][151][152] A recent phase II trial (COGiTATE) 153 showed the feasibility and safety of a CPPopt-targeted management protocol in adults with TBI, but evidence of impact on outcomes in children is needed prior to recommending widespread clinical use.…”