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Detrended fluctuation analysis (DFA) is a recently developed technique suitable for describing scaling behavior of variability in physiological signals. The purpose of this study is to explore applicability of DFA methods to intracranial pressure (ICP) signals recorded in patients with traumatic brain injury (TBI). In addition to establishing the degree of fit of the power-law scaling model of detrended fluctuations of ICP in TBI patients, we also examined the relationship of DFA coefficients (scaling exponent and intercept) to: 1) measures of initial neurological functioning; 2) measures of functional outcome at six month follow-up; and 3) measures of outcome, controlling for patient characteristics, and initial neurological status. In a sample of 147 moderate-to-severely injured TBI patients, we found that a higher DFA scaling exponent is significantly associated with poorer initial neurological functioning, and that lower DFA intercept and higher DFA scaling exponent jointly predict poorer functional outcome at six month follow-up, even after statistical control for covariates reflecting initial neurological condition. DFA describes properties of ICP signal in TBI patients that are associated with both initial neurological condition and outcome at six months postinjury.

Background: Research suggests that intracranial pressure (ICP) dynamics beyond just absolute ICP level provide information reflecting intracranial adaptive capacity. Specifically, evidence indicates that physiologic variability provides information about system functioning that may reflect dimensions of adaptive capacity. The purpose of this study was to examine the association between ICP variability in patients following moderate to severe traumatic brain injury (TBI) and outcome at hospital discharge and 6 months post-injury., Methods: ICP was monitored continuously for 4 days in 147 patients (78% male; mean (SD) age = 37 years (18 years)). ICP variability indices were calculated for four time scales (24 h, 60 min, 5 min and 5 s). Functional outcome was assessed using the Extended Glasgow Outcome Scale (GOSE). Logistic regression was used to estimate odds of survival or favorable outcome, and ordinal regression was used to estimate odds for outcome above versus below GOSE thresholds, predicted by ICP variability, controlling for age, gender, Glasgow Coma Scale motor score, craniectomy, and ICP level., Findings: ICP variability indices were better predictors of 6-month outcome than mean ICP. Survival was significantly associated with greater 5-s ICP variability (p < 0.001). Higher ICP variability on shorter time scales was associated with better functional outcome (5-s RMSSD, 5-min SD: p < 0.002; 60-min SD: p < 0.011)., Conclusions: ICP variability may reflect the degree of intactness of intracranial adaptive ability.

Background: Clinical bedside monitoring systems do not provide prominent displays of data on cerebral perfusion pressure (CPP). Immediate visual feedback would allow more rapid intervention to prevent or minimize suboptimal pressures., Objective: To evaluate the effect of a highly visible CPP display on immediate and long-term functional outcome in patients with traumatic brain injury., Methods: A total of 157 patients with traumatic brain injury at a level 1 trauma center who had invasive arterial blood pressure and intracranial pressure monitoring were randomized to beds with or without an additional, prominent continuous CPP display. Primary end points were scores on the Extended Glasgow Outcome Scale (GOSE) and Functional Status Examination (FSE) 6 months after injury. Secondary end points were GOSE scores at discharge and 3 months after injury and FSE score 3 months after injury., Results: Although GOSE and FSE scores at 6 months were better in the group with the highly visible CPP display, the differences were not significant. Slope of recovery for GOSE and FSE over all follow-up time points did not differ significantly between groups. However, the intervention's positive effect on odds of survival at hospital discharge was strong and significant. Within a subgroup of more severely injured patients, the intervention group was much less likely than the control group to have CPP deviations., Conclusions: The presence of a highly visible display of CPP was associated with significantly better odds of survival and overall condition at discharge.

This study examined the relationship of cumulative percent time that cerebral perfusion pressure (CPP) fell below set thresholds to outcome in individuals with traumatic brain injury (TBI). The sample included 157 patients (16 to 89 years of age, 79%, male) admitted to an intensive care unit at an academic medical center who underwent invasive arterial blood pressure and intracranial pressure monitoring. CPP levels were recorded continuously during the first 96 hours of monitoring. Initial neurologic status was assessed using the post-resuscitation Glasgow Coma Scale. Outcome was evaluated at hospital discharge and at six months post-injury using the Extended Glasgow Outcome Scale (GOSE). The relationship of cumulative periods of low CPP to outcome was evaluated using hierarchical and binary logistic regression analysis, controlling for age, gender, and injury severity. Patients experiencing less cumulative percent time below specific CPP thresholds were more likely to have better outcome at discharge (55 mm Hg, p = .004; 60 mm Hg, p = .008; 65 mm Hg, p = .024; 70 mm Hg, p = .016). Although differences in GOSE scores at six months were not significant, those with less time below CPP thresholds were more likely to survive. Accumulated episodes of low CPP had a stronger negative relationship with outcome in patients with more severe primary brain injury.

This study developed and tested the acceptability of a computer interface intended to provide better information about CPP to Neuro Intensive Care nurses. Maintaining adequate CPP is crucial in preventing secondary brain injury, yet current monitoring data displays have poor ergonomics that minimize usable information for clinicians. Information systems developmental methods were used to 1) formulate the model for CPP information display, 2) develop the system with end-users, and 3) install the system in the Neuro Intensive Care Unit. System testing for effects on clinicians and patient outcomes is occurring in a randomized clinical trial. Metaphor graphic and universal graphic displays were tested with 37 staff nurses from three intensive care units using continuous ICP monitoring. Nursing staff preferred an augmented universal data display to the metaphor graphics, endorsing a modified trend area graph with threshold-dependent properties. The preferred model was programmed in Visual Basic and installed on small computers that were randomly allocated as live or blank displays to beds of newly admitted head injury or aneurysmal subarachnoid hemorrhage patients with continuous monitoring. Nursing acceptability of the information interface was achieved through the use of end-user focus groups that resulted in modifying the metaphor graphic approach to a more readily understandable one.

The purpose of this study was to examine the relationship between Czosnyka and others' Pressure Reactivity Index (PRx) and neurologic outcome in patients with acute brain injury, including traumatic brain injury (TBI) and cerebrovascular pathology. PRx measures the correlation between arterial blood pressure and intracranial pressure waves and may reflect cerebral autoregulation in response to blood pressure changes. A negative PRx reflects intact cerebrovascular response, whereas a positive PRx reflects impaired response. Positive PRx has been shown to correlate with poorer outcome in individuals with TBI, but these findings have not been confirmed by replication in other studies, nor have PRx values been reported for individuals with cerebrovascular pathology. In this study, PRx was determined in 52 patients with TBI (n = 27) or cerebrovascular pathology (n = 25). Hierarchical linear regression was used to evaluate the contribution of PRx to outcome, controlling for age and Glasgow Coma Scale score. Analysis of all subjects together did not support the previously reported relationship between PRx and outcome. However, for those with TBI, positive PRx was a significant predictor of negative outcome (P = 0.03). For those with cerebrovascular pathology, the effect was not significant (P = 0.10) and was in the opposite direction. For individuals with TBI, PRx may provide useful information related to cerebral autoregulation that is predictive of outcome. The meaning of PRx in individuals with cerebrovascular pathology is unclear, and further study is needed to examine the paradoxical findings observed.

Assessment of intracranial adaptive capacity is vital in critically ill individuals with acute brain injury because there is the potential that nursing care activities and environmental stimuli to result in clinically significant increases in intracranial pressure (ICP) in a subset of individuals with decreased intracranial adaptive capacity. ICP waveform analysis provides information about intracranial dynamics that can help identify individuals who have decreased adaptive capacity and are at risk for increases in ICP and decreases in cerebral perfusion pressure, which may contribute to secondary brain injury and have a negative impact on neurologic outcome. The ability to identify high-risk individuals allows nurses to initiate interventions targeted at decreasing adaptive demand or increasing adaptive capacity in these individuals. Changes in the ICP waveform occur under various physiologic and pathophysiologic conditions and may provide valuable information about intracranial adaptive capacity. Simple visual assessment of the ICP waveform for increased amplitude and P2 elevation is clinically relevant and has been found to provide a rough indicator of decreased adaptive capacity. Advanced ICP waveform analysis techniques warrant further study as a means of dynamically assessing intracranial adaptive capacity.