Timothy Howells

The use of hyperventilation therapy after traumatic brain injury in Europe: An analysis of the BrainIT database

ObjectiveTo assess the use of hyperventilation and the adherence to Brain Trauma Foundation-Guidelines (BTF-G) after traumatic brain injury (TBI).SettingTwenty-two European centers are participating in the BrainIT initiative.DesignRetrospective analysis of monitoring data.Patients and participantsOne hundred and fifty-one patients with a known time of trauma and at least one recorded arterial blood–gas (ABG) analysis.Measurements and resultsA total number of 7,703 ABGs, representing 2,269 ventilation episodes (VE) were included in the analysis. Related minute-by-minute ICP data were taken from a 30xa0min time window around each ABG collection. Data are given as mean with standard deviation. (1) Patients without elevated intracranial pressure (ICP) (<20xa0mmHg) manifested a statistically significant higher PaCO2 (36xa0±xa05.7xa0mmHg) in comparison to patients with elevated ICP (≥20xa0mmHg; PaCO2: 34xa0±xa05.4xa0mmHg, Pxa0<xa00.001). (2) Intensified forced hyperventilation (PaCO2xa0≤xa025xa0mmHg) in the absence of elevated ICP was found in only 49 VE (2%). (3) Early prophylactic hyperventilation (<24xa0h after TBI; PaCO2xa0≤xa035xa0mmHg, ICPxa0<xa020xa0mmHg) was used in 1,224 VE (54%). (4) During forced hyperventilation (PaCO2xa0≤xa030xa0mmHg), simultaneous monitoring of brain tissue pO2 or SjvO2 was used in only 204 VE (9%).ConclusionWhile overall adherence to current BTF-G seems to be the rule, its recommendations on early prophylactic hyperventilation as well as the use of additional cerebral oxygenation monitoring during forced hyperventilation are not followed in this sample of European TBI centers.DescriptorNeurotrauma

Relationship between intracranial hemodynamics and microdialysis markers of energy metabolism and glutamate-glutamine turnover in patients with subarachnoid hemorrhage. Clinical article.

OBJECTnThe aim of this study was to explore the relationship between hemodynamics (intracranial and systemic) and brain tissue energy metabolism, and between hemodynamics and glutamate (Glt)-glutamine (Gln) cycle activity.nnnMETHODSnBrain interstitial levels of lactate, pyruvate, Glt, and Gln were prospectively monitored in the neurointensive care unit for more than 3600 hours using intracerebral microdialysis in 33 patients with subarachnoid hemorrhage (SAH). Intracranial pressure (ICP), mean arterial blood pressure, and cerebral perfusion pressure (CPP) were recorded using a digitalized system.nnnRESULTSnInterstitial Gln and pyruvate correlated with CPP (r = 0.25 and 0.24, respectively). Intracranial pressure negatively correlated with Gln (r = -0.29) and the Gln/Glt ratio (r = -0.40). Levels of Gln and pyruvate and the Gln/Glt ratio were higher and levels of Glt and lactate and the lactate/pyruvate ratio were lower during periods of decreased ICP (<or= 10 mm Hg) as compared with values in periods of elevated ICP (> 10 mm Hg). In 3 patients, a poor clinical condition was attributed to high ICP levels (range 15-25 mm Hg). When CSF drainage was increased and the ICP was lowered to 10 mm Hg, there was an instantaneous sharp increase in interstitial Glt and pyruvate in these 3 patients.nnnCONCLUSIONSnIncreasing interstitial Gln and pyruvate levels appear to be favorable signs associated with improved CPP and low ICP. The authors suggest that this pattern indicates an energy metabolic situation allowing augmented astrocytic energy metabolism with accelerated Glt uptake and Gln synthesis. Moreover, their data raised the question of whether patients with SAH and moderately elevated ICP (15-20 mm Hg) would benefit from CSF drainage at lower pressure levels than what is usually indicated in current clinical protocols.

Extended Anatomical Grading in Diffuse Axonal Injury Using MRI : Hemorrhagic Lesions in the Substantia Nigra and Mesencephalic Tegmentum Indicate Poor Long-Term Outcome

Abstract Clinical outcome after traumatic diffuse axonal injury (DAI) is difficult to predict. In this study, three magnetic resonance imaging (MRI) sequences were used to quantify the anatomical distribution of lesions, to grade DAI according to the Adams grading system, and to evaluate the value of lesion localization in combination with clinical prognostic factors to improve outcome prediction. Thirty patients (mean 31.2 years ±14.3 standard deviation) with severe DAI (Glasgow Motor Score [GMS] <6) examined with MRI within 1 week post-injury were included. Diffusion-weighted (DW), T2*-weighted gradient echo and susceptibility-weighted (SWI) sequences were used. Extended Glasgow outcome score was assessed after 6 months. Number of DW lesions in the thalamus, basal ganglia, and internal capsule and number of SWI lesions in the mesencephalon correlated significantly with outcome in univariate analysis. Age, GMS at admission, GMS at discharge, and low proportion of good monitoring time with cerebral perfusion pressure <60u2009mm Hg correlated significantly with outcome in univariate analysis. Multivariate analysis revealed an independent relation with poor outcome for age (pu2009=u20090.005) and lesions in the mesencephalic region corresponding to substantia nigra and tegmentum on SWI (pu2009=u20090.008). We conclude that higher age and lesions in substantia nigra and mesencephalic tegmentum indicate poor long-term outcome in DAI. We propose an extended MRI classification system based on four stages (stage I—hemispheric lesions, stage II—corpus callosum lesions, stage III—brainstem lesions, and stage IV—substantia nigra or mesencephalic tegmentum lesions); all are subdivided by age (≥/<30 years).

Intracerebral Microdialysis and Intracranial Compliance Monitoring of Patients with Traumatic Brain Injury

Objective. The aims of this study were to get an impression of the relationships between intracranial compliance (IC) and Lactate/Pyruvate (L/P) ratio and temperature and L/P ratio, and to determine if patients with low IC had an increased vulnerability for the secondary insult hyperthermia (as reflected in the L/P ratio). The effects of coma treatment on the results were also studied. Methods. Ten TBI patients were monitored for IC, in vivo microdialysis (MD) and bladder temperature. Mean Glasgow Coma Scale (GCS) score was 7 (range 4–10). Three patients underwent induced coma treatment. Three statistical models were used to look at the relationships between IC, temperature and L/P ratio in patients with and without coma. Results. We found that with high temperature L/P ratios increased as IC decreased (P < 0.0001). The patients with coma treatment had significantly higher average L/P ratios (P < 0.02). The effect of IC on the L/P ratio differed by coma treatment (P < 0.02). The temperature effect was not dependent on coma treatment (P < 0.49). Conclusions. These findings suggest the importance of avoiding hyperthermia in TBI patients, especially in patients with low or decreased IC (monitored or anticipated). The present technical solution seems promising for analysis of complex clinical data.

Importance of textual data in multimodality monitoring

OBJECTIVESnThe use of multimodality monitoring of patients in the intensive care unit (ICU) and the subsequent collection and analysis of such data are increasing. The aim of this work was to assess the importance of recording complementary textual data referring to patient care maneuvers, calibrations, and other incidents, in addition to the raw numerical values.nnnDESIGNnA retrospective analysis of multimodality monitoring data, which included comments entered concurrently at the bedside, collected from head-injured patients admitted to an ICU.nnnPATIENTSnOne hundred forty-seven patients with a postresuscitation Glasgow Coma Scale score of < or = 12 were monitored for a total of nearly 1 million minutes on up to eight commonly used channels.nnnMEASUREMENTS AND MAIN RESULTSnApproximately 13,000 comments were added to the raw data at the time of collection. The data were subsequently validated using these comments as indicators of artifactual values. The comments were classified into a surprisingly small number of important categories, with the most frequent referring to monitor calibrations and regular ICU care maneuvers. The difference between validated and unvalidated data on the quantity of secondary insult observed was in some cases nearly 50%.nnnCONCLUSIONSnThis work demonstrates that such textual information should be recorded concurrently with the raw monitoring values to ensure proper interpretation of the data in any retrospective analysis. Furthermore, it also suggests that a small number of prespecified categories could be used in the on-line validation of such data.

Monitoring of Cerebral Blood Flow and Metabolism Bedside in Patients with Subarachnoid Hemorrhage – A Xenon-CT and Microdialysis Study

Cerebral ischemia is the leading cause of morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). Although 70% of the patients show angiographic vasospasm only 30% develop symptomatic vasospasm defined as delayed cerebral ischemia (DCI). Early detection and management of reversible ischemia is of critical importance in patients with SAH. Using a bedside Xenon enhanced computerized tomography (Xenon-CT) scanner makes it possible to measure quantitative regional Cerebral blood flow (CBF) bedside in the neurointensive care setting and intracerebral microdialysis (MD) is a method that offers the possibility to monitor the metabolic state of the brain continuously. Here, we present results from nine SAH patients with both MD monitoring and bedside Xenon-CT measurements. CBF measurements were performed within the first 72u2009h following bleeding. Six out of nine patients developed DCI at a later stage. Five out of six patients who developed DCI had initial global CBF below 26u2009ml/100u2009g/min whereas one had 53u2009ml/100u2009g/min. The three patients who did not develop clinical vasospasm all had initial global CBF above 27u2009ml/100u2009g/min. High lactate/pyruvate (L/P) ratio was associated with lower CBF values in the area surrounding the catheter. Five out of nine patients had L/P ratio ≥25 and four of these patients had CBFu2009≤u200922u2009ml/100u2009g/min. These preliminary results suggest that patients with initially low global CBF on Xenon-CT may be more likely to develop DCI. Initially low global CBF was accompanied with metabolic disturbances determined by the MD. Most importantly, pathological findings on the Xenon-CT and MD could be observed before any clinical signs of DCI. Combining bedside Xenon-CT and MD was found to be useful and feasible. Further studies are needed to evaluate if DCI can be detected before any other signs of DCI to prevent progress to infarction.

BrainIT: a trans-national head injury monitoring research network.

BACKGROUNDnStudies of therapeutic interventions and management strategies on head injured patients are difficult to undertake. BrainIT provides validated data for analysis available to centers that contribute data to allow post-hoc analysis and hypothesis testing.nnnMETHODSnBoth physiological and intensive care management data are collected. Patient identification is eliminated prior to transfer of data to a central database in Glasgow. Requests for missing/ ambiguous data are sent back to the local center. Country coordinating centers provide advice, training, and assistance to centers and manage the data validation process.nnnRESULTSnCurrently 30 centers participate in the group. Data collection started in January 2004 and 242 patients have been recruited. Data validation tools were developed to ensure data accuracy and all analysis must be undertaken on validated data.nnnCONCLUSIONnBrainIT is an open, collaborative network that has been established with primary objectives of i) creating a core data set of information, ii) standardizing the collection methodology, iii) providing data collection tools, iv) creating and populating a data base for future analysis, and v) establishing data validation methodologies. Improved standards for multi-center data collection should permit the more accurate analysis of monitoring and management studies in head injured patients.

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

BACKGROUNDnBrainIT 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.nnnMETHODSnMinute-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.nnnCONCLUSIONnAdvances 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.

The influence of hyperthermia on intracranial pressure, cerebral oximetry and cerebral metabolism in traumatic brain injury

Abstract Background: Hyperthermia is a common secondary insult in traumatic brain injury (TBI). The aim was to evaluate the relationship between hyperthermia and intracranial pressure (ICP), and if intracranial compliance and cerebral blood flow (CBF) pressure autoregulation affected that relationship. The relationships between hyperthermia and cerebral oximetry (BtipO2) and cerebral metabolism were also studied. Methods: A computerized multimodality monitoring system was used for data collection at the neurointensive care unit. Demographic and monitoring data (temperature, ICP, blood pressure, microdialysis, BtipO2) were analyzed from 87 consecutive TBI patients. ICP amplitude was used as measure of compliance, and CBF pressure autoregulation status was calculated using collected blood pressure and ICP values. Mixed models and comparison between groups were used. Results: The influence of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) was small, but individual differences were seen. Linear mixed models showed that hyperthermia raises ICP slightly more when temperature increases in the groups with low compliance and impaired CBF pressure autoregulation. There was also a tendency (not statistically significant) for increased BtipO2, and for increased pyruvate and lactate, with higher temperature, while the lactate/pyruvate ratio and glucose were stable. Conclusions: The major finding was that the effects of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) were not extensive in general, but there were exceptional cases. Hyperthermia treatment has many side effects, so it is desirable to identify cases in which hyperthermia is dangerous. Information from multimodality monitoring may be used to guide treatment in individual patients.

Telemetric intracranial pressure monitoring: a noninvasive method to follow up children with complex craniosynostoses. A case report

IntroductionThere are no reliable noninvasive methods of monitoring ICP. Most assessments are made by indirect measures and are difficult to follow over time. Invasive studies can be used but up until now have required in-hospital transcutaneous measurements. Accurate ICP recordings over longer periods of time can be very valuable in timing different surgical procedures in syndromal cases. This case shows that telemetric ICP monitoring can be used for long-term follow-up in patients that may need repeated surgeries related to their craniosynostosis condition.Case reportIn this report, the telemetric ICP probe (Raumedic Neurovent-P-tel) was implanted before surgery and was used for repeated “noninvasive” ICP recordings pre- and postoperatively in a patient with craniosynostosis. The patient was an eight-year-old girl with pansynostosis with only the right lambdoid suture open. A telemetric ICP probe was implanted the day before cranial vault remodeling and the ICP was monitored pre- and postoperatively. The ICP was above 15xa0mmHg 72.2xa0% of the monitoring time before surgery, and the amplitude of the curve was greater than normal suggesting impaired compliance. Direct postoperative ICP was normal, and the amplitude was lower. The ICP was then monitored both in out-patient clinic and in four longer hospital stays. Both the values and the curves were analyzed, and the time with ICP above 15xa0mmHg decreased over time, and the waveform amplitude of the curves improved.ConclusionThis “noninvasive” way of recording ICP is a feasible and helpful tool in decision-making and intervening in patients with craniosynostosis.