Patricia A. Jones

Measuring the burden of secondary insults in head-injured patients during intensive care.

Primary traumatic brain damage may be compounded by secondary pathophysiological insults that can occur soon after trauma, during transfer to hospital or subsequent treatment of the head-injured patient. The aim of this prospective study was to quantify the burden of a wide range of secondary insults occurring after head injury and to relate these to 12-month outcome. In 124 adult head-injured patients studied during intensive care using a computerized data collection system, < or = 14 clinically indicated physiological variables were measured minute-by-minute. Verified values falling outside threshold limits for > or = 5 min, as defined by the Edinburgh University Secondary Insult Grading scheme, were analysed by insult grade and duration. A greater incidence of secondary insults was detected than previous studies have indicated. Insults were found in 91% of patients and occurred in all severities of head trauma, at all ages, and at every level of Injury Severity Score (ISS). The cumulative durations were much greater than previously recorded although 85% of the total time was at the least severe grade. Short duration insults were common. In 71 patients, in whom 8 insults could be assessed (intracranial pressure, arterial hypo- and hypertension, cerebral perfusion pressure, hypoxemia, pyrexia, brady- and tachycardia), outcome at 12 months was analysed using logistic regression to determine the relative influence of age, admission Glasgow Coma Sumscore, ISS, pupil response on admission, and insult duration on both mortality and morbidity. The most significant predictors of mortality in this patient set were durations of hypotensive (p = .0064), pyrexic (p = .0137), and hypoxemic (p = .0244) insults. When good versus poor outcome was considered, hypotensive insults (p = .0118) and pupil response on admission (p = .0226) were significant.

Predicting survival using simple clinical variables: a case study in traumatic brain injury

OBJECTIVES Prediction of patient outcome can be useful as an aid to clinical decision making, to explore possible biological mechanisms, and as part of the clinical audit process. Many studies have constructed predictive models for survival after traumatic brain injury, but these have often used expensive, time consuming, or highly specialised measurements. The aim of this study was to develop a simple easy to use model involving only variables which are rapidly and easily clinically achievable in routine practice. METHODS All consecutive patients admitted to a regional trauma centre with moderate or severe head injury were enrolled in the study. Basic demographic, injury, and CT characteristics were recorded. Patient survival at 1 year was used to construct a simple predictive model which was then validated on a very similar patient group. RESULTS 372 patients were included in the study, of whom 365 (98%) were followed up for survival at 1 year. Multiple logistic regression resulted in a model containing age (p<0.001), Glasgow coma scale score (p<0.001), injury severity score (p<0.001), pupil reactivity (p=0.004), and presence of haematoma on CT (p=0.004) as independently significant predictors of survival. The model was validated on an independent set of 520 patients, showing good discrimination and adequate calibration, but with a tendency to be pessimistic about very severely injured patients. It is presented as an easy to use nomogram. CONCLUSIONS All five variables have previously been shown to be related to survival. All variables in the model are clinically simple and easy to measure rapidly in a centre with access to 24 hour CT, resulting in a model that is both well validated and clinically useful.

Adding insult to injury: the prognostic value of early secondary insults for survival after traumatic brain injury

OBJECTIVES To assess the prognostic value of summary measures of secondary physiological insult in addition to baseline clinical variables for patients with traumatic brain injury. METHODS A series of 110 patients with traumatic brain injury had data on intracranial pressure (ICP), arterial blood pressure (ABP), cerebral perfusion pressure (CPP), arterial O2 saturation (SaO2), temperature in °C (Temp), and heart rate in beats/min (HRT) monitored and recorded every minute. Secondary insults were defined according to the Edinburgh University secondary insult grading system. The prognostic value of summary measures of these secondary insults was assessed by adding them to a prognostic model for survival at 1 year after controlling for baseline clinical variables using a previously validated model. RESULTS Of the eight secondary insults measured, only ICP added significantly to the prediction of survival in the first 72 hours after injury. The particular type of summary measure did not seem to influence the results. After the addition of ICP to the model, none of the other secondary insult measures could improve the predictive power of the model significantly. CONCLUSIONS Early intracranial hypertension is confirmed as a sign of poor prognosis in patients with traumatic brain injury, even after controlling for baseline clinical variables. The value or otherwise of treating such secondary insults, however, can only be definitively established in the context of prospective randomised controlled trials. The specific pathophysiological evolution of secondary insults is still the subject of much research, and a clear understanding will be necessary before the development of specific treatments is feasible.

Glasgow Outcome Scale: An inter-rater reliability study

This study was set up to test the reliability of the Glasgow Outcome Scale (GOS) when information was obtained from different sources. Eighty assessments were carried out on a group of 58 patients at three different time intervals up to 24 months post-injury. Each assessment consisted of three independently obtained GOS scores for each patient; (i) a score by a research psychologist after interview and neuropsychological testing of the patient; (ii) a score, obtained by post, by the patients general practitioner (GP), and (iii) a score made by a research worker based on questionnaire information obtained from relatives by post. The agreement between the psychologists score and that based on the relatives information was high (r = 0.79 p = 0.001) whereas the correlation between the psychologists score and that of the GP was low (r = 0.49 p = 0.001). The GPs tended to make overoptimistic assessments and this was most notable at 6 months post-injury when only 50% of the GPs assessments agreed with those of the psychologist. We have shown that reliability of the GOS varies with the method of obtaining data. Ideally patients should be interviewed and tested by staff who have not been involved in the acute care of the patient. Failing this, information should be obtained from relatives of the patient and used by staff, trained in the use of the GOS, to assign a GOS score.

Late mortality after head injury

Objectives: To investigate mortality trends in a cohort of people admitted to a regional head injury unit with all severities of injury in the calendar year 1981. Methods: A computerised database with details of 1919 admissions was compared with deaths registered by the NHS Central Register, Scotland for the years 1981 to mid-2002. Death certificate information for matches was analysed. Results: The 1919 admissions referred to 1871 individuals, comprising 93 severe, 205 moderate, and 1573 minor injuries according to Glasgow coma scale criteria. There were 57 deaths (42 severe head injuries, eight moderate, seven minor) during the initial admission, and 340 (six severe, 33 moderate, 301 minor) in the subsequent years. Substance abuse, principally alcohol, was a factor in 37 deaths, suicide accounted for 20, and accidents for 25. The great majority of these latter deaths were in people under the age of 70 years. Conclusion: Premature deaths after predominantly minor head injury are commonly alcohol related or the result of suicide or accidents.

A comparison of the Glasgow Coma Scale and the Swedish Reaction Level Scale

The Glasgow Coma Scale (GCS) and the Swedish Reaction Level Scale (RLS85), two level-of-consciousness scales used in the assessment of patients with head injury, were compared in a prospective study of 239 patients admitted to a regional head injury unit over a 4-month period. Assessments were made by nine staff members ranging from house officer to registrar, after briefing about the two scales. Data were also collected on age, nature of injuries, surgical treatment, and condition at discharge or transfer using the Glasgow Outcome Scale. Both the GCS and the RLS85 reliably identified comatose patients and those with minor head injury, but were much less effective in defining the response level in patients considered to have a moderate head injury. Only 41% of the patients allocated to a moderate-head-injury category by the GCS and the RLS85 were common to both groups. Where a mismatch occurred, neither scale allocated patients to a better or worse category more frequently than the other. Assessment of patients conscious levels using the GCS was difficult in only two cases. One patient had facial injuries, and the other was intubated. The RLS85 was reported by all users to be simpler to use than the GCS, but the latter is much more widespread in use. Both scales function well in cases of severe and minor head injury, but have weaknesses when defining moderate head injury. Level-of-consciousness scales are only an aid to assessment and the final choice between the two scales must remain a matter of personal or departmental preference.

Glasgow Head Injury Outcome Prediction Program: an independent assessment

Using an independent data set, the utility of the Glasgow Head Injury Outcome Prediction Program was investigated in terms of possible frequency of use and reliability of outcome prediction in patients with severe head injury, or haematoma requiring evacuation, or coma lasting 6 hours or more, in whom outcome had been reliably assessed at 6 to 24 months after injury. Predictions were calculated on admission, before evacuation of a haematoma, or 24 hours, 3 days, and 7 days after onset of coma lasting 6 hours or more. Three hundred and twenty four patients provided 426 predictions which were possible in 76%, 97%, 19%, 34%, and 53% of patients on admission, before operation, 24 hours, 3 days, and 7 days respectively. Major reasons for non-feasible predictions were that patients were paralysed/ventilated as part of resuscitation or management. Overall, 75.8% of predictions were correct, 14.6% were pessimistic (outcome better than predicted), and 9.6% optimistic (outcome worse than predicted). Of 197 patients (267 predictions) whose eventual outcome was good or moderate, 84.3% of predictions were correct. For death or vegetative survival (96 patients with 110 predictions), 83.6% of predictions were correct but for severe disability (31 patients with 49 predictions), only 12.2% were correctly predicted. The utility of the Glasgow Head Injury Outcome Prediction Program compares favourably with other outcome prediction algorithms for patients with head injury.

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.

A comparison of neuropsychological and functional outcome, and uptake of rehabilitation services, following severe and moderate head injury

We undertook a prospective outcome study of 61 patients with head injuries of differing severities who had been admitted to a neurosurgical unit and who survived for six months or more. Patients and relatives were interviewed and patients were neuropsychologically assessed six months from the time of injury. Details of the uptake of rehabilitation services were also collected. Three- quarters of the patients with severe head injury and two-thirds of those with moderate head injury remained severely or moderately disabled at follow-up. Both groups showed evidence of cognitive impairment and were reported by relatives to be suffering emotional and psychological problems. Whereas 54% of the severely head injured received inpatient rehabilitation, this was true of only 23% of those with moderate head injury.

Early detection of increased intracranial pressure episodes in traumatic brain injury: external validation in an adult and in a pediatric cohort

Objective: A model for early detection of episodes of increased intracranial pressure in traumatic brain injury patients has been previously developed and validated based on retrospective adult patient data from the multicenter Brain-IT database. The purpose of the present study is to validate this early detection model in different cohorts of recently treated adult and pediatric traumatic brain injury patients. Design: Prognostic modeling. Noninterventional, observational, retrospective study. Setting and Patients: The adult validation cohort comprised recent traumatic brain injury patients from San Gerardo Hospital in Monza (n = 50), Leuven University Hospital (n = 26), Antwerp University Hospital (n = 19), Tübingen University Hospital (n = 18), and Southern General Hospital in Glasgow (n = 8). The pediatric validation cohort comprised patients from neurosurgical and intensive care centers in Edinburgh and Newcastle (n = 79). Interventions: None. Measurements and Main Results: The model’s performance was evaluated with respect to discrimination, calibration, overall performance, and clinical usefulness. In the recent adult validation cohort, the model retained excellent performance as in the original study. In the pediatric validation cohort, the model retained good discrimination and a positive net benefit, albeit with a performance drop in the remaining criteria. Conclusions: The obtained external validation results confirm the robustness of the model to predict future increased intracranial pressure events 30 minutes in advance, in adult and pediatric traumatic brain injury patients. These results are a large step toward an early warning system for increased intracranial pressure that can be generally applied. Furthermore, the sparseness of this model that uses only two routinely monitored signals as inputs (intracranial pressure and mean arterial blood pressure) is an additional asset.