C. Contant

Prognostic factors in supratentorial ganglioglioma.

Summary Although gangliogliomas are often associated with long survival, efforts to identify specific prognostic factors in these tumors have been largely unsuccessful. To identify factors associated with long survival, we retrospectively reviewed 42 cases of supratentorial ganglioglioma surgically treated at our institution since 1985. Data analysis included Kaplan-Meier survival curves and log-rank tests of the effects of individual variables. The Cox proportional hazards method was used to fit a model incorporating several variables simultaneously. The 42 cases included 21 male and 21 female patients with an average age at surgery of 31 years. Length of follow-up averaged 48 months. Ten patients died an average of 38 months after surgery. Factors found to have a significant correlation with mortality were older age at diagnosis (P=0.012), male gender (P=0.034), and malignant glial features (P=0.020). Presenting symptoms, location of tumor, adjuvant radiation therapy, and extent of surgical resection were not significantly related to survival. These results are the first to demonstrate an association between prognostic factors and outcome in patients with supratentorial ganglioglioma.

Bench test assessment of the new Raumedic Neurovent-P ICP sensor: a technical report by the BrainIT group

Summary.Background. In clinical practice, fiberberoptic and piezo-electric ICP probes are often used for measuring intracranial pressure (ICP). A number of similar technologies, although performing well in bench test studies, have been shown to exhibit unacceptable zero drift, fragility or both during trials conducted under clinical conditions. Recently, a new technology has become available, the Neurovent-P (Raumedic AG + CO, Raumedic, Germany). As a pre-requisite for a clinical trial, we have conducted and report on bench test studies to confirm the manufacturer’s long term zero-drift performance for this technology.Method. In a test rig static tests (recording of 20 mmHg pressure) and dynamic tests, ranging from 5 to 50 mmHg have been performed.Findings. 10 ICP probes have been tested for a total of 60 days. All the catheters, after the connection with the ICU monitor displayed a static pressure of 0 ± 1 mmHg and did not required pre-insertion alteration. At five days, mean zero drift was 0.6 ± 0.9 mmHg. Overall, zero drift ranged from 0 to 2 mmHg. At a fixed static pressure of 20 mmHg, the mean recorded value was 20.6 ± 0.8 mmHg, ranging from 19 to 23 mmHg. A regression analysis of the relationship between the applied pressure and the recorded pressure during the dynamic tests of the 10 catheters yielded a correlation coefficient R2 of 0.997. Applying the Altman and Bland method to assess the bias and confidence limits for the Raumedic catheter responses during the dynamic tests against the applied gold-standard hydrostatic column pressures, the average bias of −0.66 ± 0.85 mmHg, with 95% CLs of −2 mmHg and 1 mmHg.Conclusions. Mean zero drift, after five days, was very small and long-term continuous recording of a stable pressure was very precise. The response at dynamic tests, i.e. the changes of pressure in a wide range, was excellent. The average bias of the Raumedic catheter compared with the hydrostatic column is very small. After this bench test, the next and most critical step will be to conduct a trial of this promising technology under more demanding clinical environment.

R3-Survey of traumatic brain injury management in European Brain IT centres year 2001

Objective To obtain knowledge about the conditions and management of traumatic brain injury (TBI) in a collaborative network of Brain Information Technology centres.Design The Brain IT (Brain monitoring with Information Technology) survey comprised two parts: local conditions and policies (part A), and a case study part (part B). The information was gathered by written questionnaires followed by telephone interviews.Participants Twenty-four Brain IT centres participated (two respondents from 18 sites).Results The average proportion of agreement between duplicate respondents was 0.79 (range 0.44–1.00). All Brain IT centres monitored ICP. The reported order of treatment for intracranial hypertension was: evacuation of mass-lesions and head elevation (1), increase of sedation and Mannitol scheme (2), hyperventilation (3), ventricular drainage (4), craniectomy and pentothal coma (5), and decompressive lobectomy (6). The respondents were less prone to evacuate expansive contusions in relation to extra cerebral hematomas. The most common suggested interventions (alone or in combination) for treatment of intracranial hypertension without mass lesions was the Mannitol scheme (included in 71% of the suggestions), CSF drainage (included in 56%), hyperventilation (included in 32%), and pentothal coma (included in 22%).Conclusions The suggested management of TBI was mainly in accordance with published guidelines, although a minor proportion of the answers deviated to some extent. The suggested order and combinations of different treatment interventions varied. Variation of treatment within the range of prescribed standards provides optimal conditions for an interesting future analysis of treatment and monitoring data as collected prospectively in a Brain IT database.

Continuous cerebral compliance monitoring in severe head injury: its relationship with intracranial pressure and cerebral perfusion pressure.

SummaryBackground. Cerebral compliance expresses the capability to buffer an intracranial volume increase while avoiding a rise in intracranial pressure (ICP). The autoregulatory response to Cerebral Perfusion Pressure (CPP) variation influences cerebral blood volume which is an important determinant of compliance. The direction of compliance change in relation to CPP variation is still under debate. The aim of the study was to investigate the relationship between CPP and compliance in traumatic brain injured (TBI) patients by a new method for continuous monitoring of intracranial compliance as used in neuro-intensive care (NICU).Method. Three European NICU’s standardised collection of CPP, compliance and ICP data to a joint database. Data were analyzed using an unpaired student t-test and a multi-level statistical model.Results. For each variable 108,263 minutes of data were recorded from 21 TBI patients (19 patients GCS≤8; 90% male; age 10–77 y). The average value for the following parameters were: ICP 15.1±8.9 mmHg, CPP 74.3±14 mmHg and compliance 0.68±0.3 ml/mmHg. ICP was ≥20 mmHg in 20% and CPP<60 mmHg for 10.7% of the time. Compliance was lower (0.51±0.34 ml/mmHg) at ICP≥20 than at ICP<20 mmHg (0.73±0.37 ml/mmHg) (p<0.0001). Compliance was significantly lower at CPP<60 than at CPP≥60 mmHg: 0.56±0.36 and 0.70±0.37 ml/mmHg respectively (p<0.0001). The CPP – compliance relationship was different when ICP was above 20 mmHg compared with below 20 mmHg. At ICP<20 mmHg compliance rose as CPP rose. At ICP≥20 mmHg, the relation curve was convexly shaped. At low CPP, the compliance was between 0.20 and 0.30 ml/mmHg. As the CPP reach 80 mmHg average compliance was 0.55 ml/mmHg., but compliance fell to 0.40 ml/mmHg when CPP was 100 mmHg.Conclusions. Low CPP levels are confirmed to be detrimental for intracranial compliance. Moreover, when ICP was pathological, indicating unstable intracranial equilibrium, a high CPP level was also associated with a low volume-buffering capacity.

Multi-Centre Assessment of the Spiegelberg Compliance Monitor: Interim Results

Analyses of a multi-centre database of 71 patients at risk of raised ICP showed that in head injured patients (n = 19) and tumour patients (n = 13) clear inverse relationships of ICP vs compliance exist. SAH patients (n = 5) appear to exhibit a biphasic relationship between ICP and compliance, however greater numbers of patients need to be recruited to this group. Patients with hydrocephalus (n = 34) show an initial decrease in compliance while ICP is less than 20 mmHg, thereafter compliance does not show a dependence upon ICP. A power analysis confirmed that sufficient numbers of patients have been recruited in the hydrocephalus group and a ROC analysis determined that a mean compliance value of 0.809 (lower and upper 95% CL = 0.725 & 0.894 resp.) was a critical threshold for raised ICP greater than 10 mmHg. Preliminary time-series analyses of the ICP and compliance data is revealing evidence that the cumulative time compliance is in a low compliance state (< 0.5 ml/mmHg), as a proportion of total monitoring time, increases more rapidly than the cumulative time ICP is greater than 25 mmHg. Before trials testing compliance thresholds can be designed, we need to consider not just the absolute threshold, but the duration of time spent below threshold. A survey may be required to identify a consensus of what is the minimum duration of raised ICP above 25 mmHg needed to instigate treatment.

Clinical experience in the use of the Spiegelberg automated compliance device in the assessment of patients with hydrocephalus.

Deciding upon shunting in patients with hydrocephalus with possibly related symptomatology, is difficult. The Spiegelberg automated device allows continuous measurements of intracranial compliance. We aimed to evaluate the added information that this new technology can provide, in addition to standard continuous ICP monitoring. Thirty-three patients with hydrocephalus were continuously monitored for ICP and compliance. Patients with abnormal ICP or compliance profiles were selected for shunting. Thirteen patients underwent ventriculo-peritoneal shunting on this basis, with 12 obtaining benefit and one dying as a complication of shunt-related sepsis. The 13 patients undergoing shunting had abnormalities in either intracranial pressure or compliance or both. Only 1 patient had normal ICP, but abnormal compliance and so the true complementary role of continuous compliance measurements cannot be determined. It is proposed that further recruitment be on a larger multi-centre basis. Determination of benefit is required, particularly as a possible time lag of abnormal ICP abnormal compliance over appearing during monitoring can be demonstrated.

Multi-Centre Assessment of the Spiegelberg Compliance Monitor: Preliminary Results

Acute brain injury states (e.g. head injury, subarachnoid haemorrhage) show clear inverse relationships of ICP vs compliance, with ICP instability at times of lower compliance states. Variance in compliance values is large in hydrocephalus where ICP is relatively lower and compliance higher. Nonetheless, early experience shows that compliance data influence decisions on CSF diversion treatments. Future work will focus on the ability of intracranial compliance to predict ensuing ICP instability and methodological refinement for monitoring patients who have higher compliance states.

Accurate data collection for head injury monitoring studies: a data validation methodology.

BACKGROUND BrainIT is a multi centre, European project, to collect high quality continuous data from severely head injured patients using a previously defined [6] core data set. This includes minute-by-minute physiological data and simultaneous treatment and management information. It is crucial that the data is correctly collected and validated. METHODS Minute-by-minute physiological monitoring data is collected from the bedside monitors. Demographic and clinical information, intensive care management and secondary insult management data, are collected using a handheld computer. Data is transferred from the handheld device to a local computer where it is reviewed and anonymised before being sent electronically, with the physiological data, to the central database in Glasgow. Automated computer tools highlight missing or ambiguous data. A request is then sent to the contributing centre where the data is amended and returned to Glasgow. Of the required data elements 20% are randomly selected for validation against original documentation along with the actual number of specific episodic events during a known period. This will determine accuracy and the percentage of missing data for each record. CONCLUSION Advances in patient care require an improved evidence base. For accurate, consistent and repeatable data collection, robust mechanisms are required which should enhance the reliability of clinical trials, assessment of management protocols and equipment evaluations.

Assessment of different data representations and averaging methods on the Spiegelberg compliance device

The Spiegelberg Compliance Device (Spiegelberg KG, Hamburg, Germany) has been available for the automated measurement and calculation of minute by minute intracranial compliance. Widespread practical use has been somewhat limited by the instability of values: especially at low intracranial pressures. We looked at two aspects of a methodology in an attempt to increase the value of the Spiegelberg device in the clinical setting. Firstly, we discussed the difference in representing measured values as elastance (dp/dv) instead of compliance (dv/dp); and secondly we proposed the use of an averaging algorithm called the Exponentially Weighted Moving Average (ewma), which could be applied as a flexible method to follow trends and rapid changes in the elastance (or compliance). Clinical data from sixteen patients were gathered and statistical analysis was focused on three particular aspects, the coefficient of variation which indicates the variability of data values, the correlation between the elastance (or compliance) time series and the underlying ICP signal and the percentage of outliers greater than 2.5 standard deviations from the mean. Our results showed that expressing elastance (dp/dv) instead of compliance (dv/dp) yielded fewer outliers and had a better correlation to ICP, and the ewma method had a better correlation to ICP than the Spiegelberg method.