Cerebrovascular Autoregulation Monitoring in the Management of Adult Severe Traumatic Brain Injury: A Delphi Consensus of Clinicians

BACKGROUND

Several methods have been proposed to measure cerebrovascular autoregulation (CA) in traumatic brain injury (TBI), but the lack of a gold standard and the absence of prospective clinical data on risks, impact on care and outcomes of implementation of CA-guided management lead to uncertainty.

AIM

To formulate statements using a Delphi consensus approach employing a group of expert clinicians, that reflect current knowledge of CA, aspects that can be implemented in TBI management and CA research priorities.

METHODS

A group of 25 international academic experts with clinical expertise in the management of adult severe TBI patients participated in this consensus process. Seventy-seven statements and multiple-choice questions were submitted to the group in two online surveys, followed by a face-to-face meeting and a third online survey. Participants received feedback on average scores and the rationale for resubmission or rephrasing of statements. Consensus on a statement was defined as agreement of more than 75% of participants.

RESULTS

Consensus amongst participants was achieved on the importance of CA status in adult severe TBI pathophysiology, the dynamic non-binary nature of CA impairment, its association with outcome and the inadvisability of employing universal and absolute cerebral perfusion pressure targets. Consensus could not be reached on the accuracy, reliability and validation of any current CA assessment method. There was also no consensus on how to implement CA information in clinical management protocols, reflecting insufficient clinical evidence.

CONCLUSION

The Delphi process resulted in 25 consensus statements addressing the pathophysiology of impaired CA, and its impact on cerebral perfusion pressure targets and outcome. A research agenda was proposed emphasizing the need for better validated CA assessment methods as well as the focused investigation of the application of CA-guided management in clinical care using prospective safety, feasibility and efficacy studies.

Incidence of chronic subdural haematoma: a single-centre exploration of the effects of an ageing population with a review of the literature

BACKGROUND

Chronic subdural haematoma (cSDH) is a common neurosurgical pathology frequently occurring in older patients. The impact of population ageing on cSDH caseload has not been examined, despite relevance for health system planning.

METHODS

This is a single-centre study from the UK. Operated cases of cSDH (n = 446) for 2015-2018 were identified. Crude and directly standardised incidence rates were calculated. Medline and EMBASE were systematically searched to identify studies reporting on the incidence of cSDH by year, so an estimate of rate of incidence change could be determined. Local incidence rates were then applied to population projections for local catchment area to estimate operated cSDH numbers at 5 yearly intervals due to shifting demographics.

RESULTS

We identified nine studies presenting incidence estimates. Crude estimates for operative cases ranged from 1.3/100,000/year (1.4-2.2) to 5.3/100,000/year (4.3-6.6). When non-operated cases were included, incidence was higher: 8.2/100,000/year (6.0-11.2) to 48/100,000/year (37.7-61.1). Four pairs of studies demonstrated incidence rate increases of 200-600% over the last 50 years, but data was deemed too heterogeneous to generate formal estimate of incidence change. Local crude incidence of operated cSDH was 3.50/100,000/year (3.19-3.85). Directly standardised incidence was 1.58/100,000/year (1.26-1.90). After applying local incidence rates to population projections, case numbers were predicted to increase by 53% over the next 20 years.

CONCLUSIONS

The incidence of cSDH is increasing. We project a 53% increase in operative caseload within our region by 2040. These are important findings for guiding future healthcare planning.

Variation in the practice of tracheal intubation in Europe after traumatic brain injury: a prospective cohort study

Traumatic brain injury patients frequently undergo tracheal intubation. We aimed to assess current intubation practice in Europe and identify variation in practice. We analysed data from patients with traumatic brain injury included in the prospective cohort study collaborative European neurotrauma effectiveness research in traumatic brain injury (CENTER‐TBI) in 45 centres in 16 European countries. We included patients who were transported to hospital by emergency medical services. We used mixed‐effects multinomial regression to quantify the effects on pre‐hospital or in‐hospital tracheal intubation of the following: patient characteristics; injury characteristics; centre; and trauma system characteristics. A total of 3843 patients were included. Of these, 1322 (34%) had their tracheas intubated; 839 (22%) pre‐hospital and 483 (13%) in‐hospital. The fit of the model with only patient characteristics predicting intubation was good (Nagelkerke R2 64%). The probability of tracheal intubation increased with the following: younger age; lower pre‐hospital or emergency department GCS; higher abbreviated injury scale scores (head and neck, thorax and chest, face or abdomen abbreviated injury score); and one or more unreactive pupils. The adjusted median odds ratio for intubation between two randomly chosen centres was 3.1 (95%CI 2.1–4.3) for pre‐hospital intubation, and 2.7 (95%CI 1.9–3.5) for in‐hospital intubation. Furthermore, the presence of an anaesthetist was independently associated with more pre‐hospital intubation (OR 2.9, 95%CI 1.3–6.6), in contrast to the presence of ambulance personnel who are allowed to intubate (OR 0.5, 95%CI 0.3–0.8). In conclusion, patient and injury characteristics are key drivers of tracheal intubation. Between‐centre differences were also substantial. Further studies are needed to improve the evidence base supporting recommendations for tracheal intubation.

Serum sodium and intracranial pressure changes after desmopressin therapy in severe traumatic brain injury patients: a multi-centre cohort study

Background

In traumatic brain injury (TBI) patients desmopressin administration may induce rapid decreases in serum sodium and increase intracranial pressure (ICP).

Aim

In an international multi-centre study, we aimed to report changes in serum sodium and ICP after desmopressin administration in TBI patients.

Methods

We obtained data from 14 neurotrauma ICUs in Europe, Australia and UK for severe TBI patients (GCS ≤ 8) requiring ICP monitoring. We identified patients who received any desmopressin and recorded daily dose, 6-hourly serum sodium, and 6-hourly ICP.

Results

We studied 262 severe TBI patients. Of these, 39 patients (14.9%) received desmopressin. Median length of treatment with desmopressin was 1 [1–3] day and daily intravenous dose varied between centres from 0.125 to 10 mcg. The median hourly rate of decrease in serum sodium was low (− 0.1 [− 0.2 to 0.0] mmol/L/h) with a median period of decrease of 36 h. The proportion of 6-h periods in which the rate of natremia correction exceeded 0.5 mmol/L/h or 1 mmol/L/h was low, at 8% and 3%, respectively, and ICPs remained stable. After adjusting for IMPACT score and injury severity score, desmopressin administration was independently associated with increased 60-day mortality [HR of 1.83 (1.05–3.24) (p = 0.03)].

Conclusions

In severe TBI, desmopressin administration, potentially representing instances of diabetes insipidus is common and is independently associated with increased mortality. Desmopressin doses vary markedly among ICUs; however, the associated decrease in natremia rarely exceeds recommended rates and median ICP values remain unchanged. These findings support the notion that desmopressin therapy is safe.

Kinetic modelling of serum S100b after traumatic brain injury

Background

An understanding of the kinetics of a biomarker is essential to its interpretation. Despite this, little kinetic modelling of blood biomarkers can be found in the literature. S100b is an astrocyte related marker of brain injury used primarily in traumatic brain injury (TBI). Serum levels are expected to be the net result of a multi-compartmental process. The optimal sample times for TBI prognostication, and to follow injury development, are unclear. The purpose of this study was to develop a kinetic model to characterise the temporal course of serum S100b concentration after primary traumatic brain injury.

Methods

Data of serial serum S100b samples from 154 traumatic brain injury patients in a neurointensive care unit were retrospectively analysed, including only patients without secondary peaks of this biomarker. Additionally, extra-cranial S100b can confound samples earlier than 12 h after trauma and were therefore excluded. A hierarchical, Bayesian gamma variate kinetic model was constructed and the parameters estimated by Markov chain Monte Carlo sampling.

Results

We demonstrated that S100b concentration changes dramatically over timescales that are clinically important for early prognostication with a peak at 27.2 h (95 % credible interval [25.6, 28.8]). Baseline S100b levels was found to be 0.11 μg/L (95 % credible interval [0.10, 0.12]).

Conclusions

Even small differences in injury to sample time may lead to marked changes in S100b during the first days after injury. This must be taken into account in interpretation. The model offers a way to predict the peak and trajectory of S100b from 12 h post trauma in TBI patients, and to identify deviations from this, possibly indicating a secondary event. Kinetic modelling, providing an equation for the peak and projection, may offer a way to reduce the ambiguity in interpretation of, in time, randomly sampled acute biomarkers and may be generally applicable to biomarkers with, in time, well defined hits.

Action against vaccine-preventable infectious diseases and tuberculosis in Nomad Camps: the experience of a Local Health Unit in Rome

In Italy the highest incidence of Tuberculosis (TB) cases is in young adult migrants. In 2011, the sanitarystaff of the Local Health Unit (ASL) Roma A promoted a vaccination campaign conducting several public health interventions in Nomad Camps. After notification of a case of TB in the Camp of Via Salaria, out of 357 Mantoux skin tests performed, 93 were positive (26%); subsequently, 5 subjects with radiographic positivity were hospitalized. The vaccination campaign was carried out to prevent the spread of infectious diseases in immigrant communities at high risk of contagion and to avoid the consequent transmission in the host country. As a result, vaccinations coverage among the residents of the Camps increased: 367 vaccinated subjects (30% more than previous year) and 612 administered vaccinations.

Variation between countries in the frequency of diabetic ketoacidosis at first presentation of type 1 diabetes in children: a systematic review

AIMS/HYPOTHESIS

Type 1 diabetes is the most frequent endocrine disease in children, with 65,000 children diagnosed worldwide every year. Up to 80% of these children present with diabetic ketoacidosis (DKA), which is associated with both short-term risks and long-term consequences. This study aimed to characterise the worldwide variation in presentation of type 1 diabetes to inform future interventions to reduce this excess morbidity and mortality.

METHODS

This was a systematic review of studies indexed on PubMed, EMBASE, Web of Science, Scopus or CINAHL before March 2011 that included unselected groups of children presenting with new-onset type 1 diabetes, reported the proportion presenting with DKA and used a definition of DKA based on measurement of pH or bicarbonate.

RESULTS

Sixty-five studies of cohorts comprising over 29,000 children in 31 countries were included. The frequency of DKA at diagnosis ranged from 12.8% to 80%, with highest frequencies in the United Arab Emirates, Saudi Arabia and Romania, and the lowest in Sweden, the Slovak Republic and Canada. Multivariable modelling showed the frequency of DKA was inversely associated with gross domestic product, latitude and background incidence of type 1 diabetes.

CONCLUSIONS/INTERPRETATION

This is the first description of the variation in frequency of DKA at presentation of type 1 diabetes in children across countries. It demonstrates large variations that may, at least in part, be explained by different levels of disease awareness and healthcare provision and suggests ways to decrease the excess morbidity and mortality associated with DKA at diagnosis.

Errors during the preparation of drug infusions: a randomized controlled trial

BACKGROUND

We investigated the extent and frequency of dose errors and treatment delays made as a consequence of preparing drug infusions at the bedside, rather than using pre-filled syringes.

METHODS

Forty-eight nurses with critical care experience volunteered to take part in this randomized, blinded, controlled study conducted in the simulation centre of an urban hospital. They assisted in the management of a simulated patient with septic shock. Vasopressor infusions were prepared either by diluting concentrated drugs from ampoules or were provided in syringes pre-filled beforehand by an intensive care unit resident.

RESULTS

The time taken for the infusion to be started and the final concentration of the drugs were measured. We also measured the concentration of infusions prepared by a pharmacist and a pharmaceutical company. Nurses took 156 s to start infusions when using pre-filled syringes compared with 276 s when preparing them de novo, a mean delay of 106 s [95% confidence interval (CI) 73-140 s, P<0.0001]. One infusion prepared from ampoules contained one-fifth of the expected concentration of epinephrine; another contained none at all. Medication errors were 17.0 times less likely when pre-filled syringes were used (95% CI 5.2-55.5), and infusions prepared by pharmacy and industry were significantly more likely to contain the expected concentration (P<0.001 for norepinephrine and P=0.001 for epinephrine).

CONCLUSIONS

Providing drug infusions in syringes pre-filled by pharmacists or pharmaceutical companies would reduce medication errors and treatment delays, and improve patient safety. However, this approach would have substantial financial implications for healthcare providers, especially in less developed countries.

[Prevention and control of tuberculosis in the hospital setting: the new operative protocol of the polyclinic "Umberto I"]

The aim of this contribution is to explain a recent tubercolosis "prevention and control" program in health care workers. The same program was implemented in an university hospital since 2007, and revised in 2011 as a result of a new Mycobacterium tubercolosis exposure assessment in the different works environment.

Modelling the impact of pandemic influenza A(H1N1) on UK paediatric intensive care demand

BACKGROUND

Each winter seasonal respiratory virus infections account for large variations in unplanned admission to UK paediatric intensive care units (PICU). The emergence of pandemic influenza A(H1N1) has been associated with a notable predominance in children and may be expected to have a significant impact on PICU provision.

AIMS

To derive conservative projections for PICU demand from current data and examine the effect of regional variations in bed provision.

METHODS AND RESULTS

PICU demand was estimated with the FluSurge 2.0 model using age-stratified data for the UK population and recently published conservative estimates for epidemiological parameters. The data suggest that a significant proportion of current total capacity may be required at the peak of the pandemic. Variation in per capita critical care provision across the UK leads to a wide range in potential impact at a regional level.

CONCLUSIONS

Contingency measures for children needing paediatric intensive care are needed to absorb the likely increase in activity expected due to pandemic influenza this winter. Because of variations in provision by region, the role of paediatric retrieval services will be especially important.

Modelling the impact of an influenza A/H1N1 pandemic on critical care demand from early pathogenicity data: the case for sentinel reporting

Projected critical care demand for pandemic influenza H1N1 in England was estimated in this study. The effect of varying hospital admission rates under statistical uncertainty was examined. Early in a pandemic, uncertainty in epidemiological parameters leads to a wide range of credible scenarios, with projected demand ranging from insignificant to overwhelming. However, even small changes to input assumptions make the major incident scenario increasingly likely. Before any cases are admitted to hospital, 95% confidence limit on admission rates led to a range in predicted peak critical care bed occupancy of between 0% and 37% of total critical care bed capacity, half of these cases requiring ventilatory support. For hospital admission rates above 0.25%, critical care bed availability would be exceeded. Further, only 10% of critical care beds in England are in specialist paediatric units, but best estimates suggest that 30% of patients requiring critical care will be children. Paediatric intensive care facilities are likely to be quickly exhausted and suggest that older children should be managed in adult critical care units to allow resource optimisation. Crucially this study highlights the need for sentinel reporting and real-time modelling to guide rational decision making.

Attenuation in invasive blood pressure measurement systems

Poor fidelity invasive arterial blood pressure (IABP) traces are a frequent practical problem. It is common practice to describe any such trace as being 'damped'; the resonance behaviour of IABP measurement systems having been extensively described in the literature. However, as poor quality arterial blood pressure signals are seen even with optimal pressure transduction circuits, this cannot be the sole mechanism. In this commentary the classical lumped-parameter Windkessel model is extended by postulating an additional impedance proximal to the site of IABP measurement. This impedance represents any mechanical obstruction to laminar flow. Equations are presented relating measured and actual arterial blood pressures in terms of the model impedances. The reactive properties of such a partial obstruction may lead to an IABP trace that is superficially similar in appearance to the case of an over-damped measurement system. However, this phenomenon should be termed 'attenuation' rather than 'damping' and is probably more common. The distinction is of practical importance as the behaviour of the measured systolic and diastolic pressures is different -- both are systematically underestimated and the mean arterial pressure is thus not preserved. Furthermore, this error varies inversely with the peripheral vascular resistance of the tissues distal to the measurement point, therefore apparently magnifying the effect of vasodilatation on blood pressure or derived quantities.

Collusion detection in multiple choice examinations

OBJECTIVE

To develop and test a novel method for collusion detection in multiple choice examinations.

SUBJECTS AND METHODS

Answers from two negatively marked medical prize examinations for two different years were analysed. Both examinations were administered electronically. One examination was formally invigilated, while the second was not; instead, candidates were able to sit the test at any time and at any computer with an internet connection. We examine pairs of students and compare correlations between their answers. Our approach allows us to correct for the difficulty of individual questions and for the estimated ability and the degree of risk aversion of the students. We compare the results of this statistical analysis with other information on the timing of the answers and the physical location of the computer, both of which are available to the web-server.

RESULTS

Significant correlation between several candidates who either admitted having cheated or could be linked to other corroborating evidence of collusion was found.

CONCLUSION

It is possible to detect collusion in multiple choice examinations in a statistical way by examining the patterns of answers between pairs of candidates. In examinations that are delivered on-line, information is often available on the location of the candidates and the timings of their answers, and can be used as additional corroborative evidence.