Epidural monitoring of the intracranial pressure in severe head injury characterized by non-localizing motor response

Intracranial pressure monitoring: fundamental considerations and rationale for monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.

Brief episodes of intracranial hypertension and cerebral hypoperfusion are associated with poor functional outcome after severe traumatic brain injury

BACKGROUND

Management strategies after severe traumatic brain injury (TBI) target prevention and treatment of intracranial hypertension (ICH) and cerebral hypoperfusion (CH). We have previously established that continuous automated recordings of vital signs (VS) are more highly correlated with outcome than manual end-hour recordings. One potential benefit of automated vital sign data capture is the ability to detect brief episodes of ICH and CH. The purpose of this study was to establish whether a relationship exists between brief episodes of ICH and CH and outcome after severe TBI.

MATERIALS

Patients at the R Adams Cowley Shock Trauma Center were prospectively enrolled over a 2-year period. Inclusion criteria were as follows: age >14 years, admission within the first 6 hours after injury, Glasgow Coma Scale score <9 on admission, and placement of a clinically indicated ICP monitor. From high-resolution automated VS data recording system, we calculated the 5-minute means of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and Brain Trauma Index (BTI = CPP/ICP). Patients were stratified by mortality and 6-month Extended Glasgow Outcome Score (GOSE).

RESULTS

Sixty subjects were enrolled with a mean admission Glasgow Coma Scale score of 6.4 ± 3.1, a mean Head Abbreviated Injury Severity Scale score of 4.2 ± 0.7, and a mean Marshall CT score of 2.5 ± 0.9. Significant differences in the mean number of brief episodes of CPP <50 and BTI <2 in patients with a GOSE 1-4 versus GOSE 5-8 (9.4 vs. 4.7, p = 0.02 and 9.3 vs. 4.9, p = 0.03) were found. There were significantly more mean brief episodes per day of ICP >30 (0.52 vs. 0.29, p = 0.02), CPP <50 (0.65 vs. 0.28, p < 0.001), CPP <60 (1.09 vs. 0.7, p = 0.03), BTI <2 (0.66 vs. 0.31, p = 0.002), and BTI <3 (1.1 vs. 0.64, p = 0.01) in those patients with GOSE 1-4. Number of brief episodes of CPP <50, CPP <60, BTI <2, and BTI <3 all demonstrated high predictive power for unfavorable functional outcome (area under the curve = 0.65-0.75, p < 0.05).

CONCLUSIONS

This study demonstrates that the number of brief 5-minute episodes of ICH and CH is predictive of poor outcome after severe TBI. This finding has important implications for management paradigms which are currently targeted to treatment rather than prevention of ICH and CH. This study demonstrates that these brief episodes may play a significant role in outcome after severe TBI.

Contribution of raised ICP and hypotension to CPP reduction in severe brain injury: correlation to outcome

The aim of this study was to determine to what degree hypotension and ICP contribute to the reduction of cerebral perfusion pressure (CPP), particularly in light of the shift in emphasis to CPP management by the use of pressors. The study population consisted of severely head injured patients extracted retrospectively from the Traumatic Coma Data Bank and compared with 139 patients from the Smith Kline component of the American Brain Injury Consortium database where outcome was available. The percentage time that ICP exceeded 20 mm Hg and CPP less than 60 mm Hg was computed for 5 days post injury. At each hour when CPP was less than 60 mm Hg the contribution of raised ICP and low arterial pressure or both was determined. In the first cohort, hypotension was the predominant factor leading to CPP reduction. With use of the CPP concept of treatment, the major contribution to CPP shifted to ICP and arterial hypotension played less of a role. Overall, CPP management has been associated with improved outcome.