Transcranial Doppler to Predict Neurologic Outcome after Mild to Moderate Traumatic Brain Injury.

BACKGROUND: To assess the performance of transcranial Doppler (TCD) in predicting neurologic worsening after mild to moderate traumatic brain injury. METHODS: The authors conducted a prospective observational study across 17 sites. TCD was performed upon admission in 356 patients (Glasgow Coma Score [GCS], 9 to 15) with mild lesions on cerebral computed tomography scan. Normal TCD was defined as a pulsatility index of less than 1.25 and diastolic blood flow velocity higher than 25 cm/s in the two middle cerebral arteries. The primary endpoint was secondary neurologic deterioration on day 7. RESULTS: Twenty patients (6%) developed secondary neurologic deterioration within the first posttraumatic week. TCD thresholds had 80% sensitivity (95% CI, 56 to 94%) and 79% specificity (95% CI, 74 to 83%) to predict neurologic worsening. The negative predictive values and positive predictive values of TCD were 98% (95% CI, 96 to 100%) and 18% (95% CI, 11to 28%), respectively. In patients with minor traumatic brain injury (GCS, 14 to 15), the sensitivity and specificity of TCD were 91% (95% CI, 59 to 100%) and 80% (95% CI, 75 to 85%), respectively. The area under the receiver operating characteristic curve of a multivariate predictive model including age and GCS was significantly improved with the adjunction of TCD. Patients with abnormal TCD on admission (n = 86 patients) showed a more altered score for the disability rating scale on day 28 compared to those with normal TCD (n = 257 patients). CONCLUSIONS: TCD measurements upon admission may provide additional information about neurologic outcome after mild to moderate traumatic brain injury. This technique could be useful for in-hospital triage in this context. (Anesthesiology 2016; 125:346-54).

Experimental evolution of selfish policing in social bacteria.

Cooperative organisms evolve within socially diverse populations. In populations harboring both cooperators and cheaters, cooperators might adapt by evolving novel interactions with either social type or both. Diverse animal traits suppress selfish behaviors when cooperation is important for fitness, but the potential for prokaryotes to evolve such traits is unclear. We allowed a strain of the bacterium Myxococcus xanthus that is proficient at cooperative fruiting body development to evolve while repeatedly encountering a non-evolving developmental cheater. Evolving populations greatly increased their fitness in the presence of the cheater, both relative to their ancestor and in terms of absolute spore productivity. However, the same evolved lineages exhibited a net disadvantage to the ancestor in the cheater's absence. Evolving populations reversed a large ancestral disadvantage to the cheater into competitive superiority and also evolved to strongly suppress cheater productivity. Moreover, in three-party mixes with the cheater, evolved populations enhanced their ancestor's productivity relative to mixes of only the ancestor and cheater. Thus, our evolved populations function as selfish police that inhibit cheaters, both to their own advantage and to the benefit of others as well. Cheater suppression was general across multiple unfamiliar cheaters but was more pronounced against the evolutionarily familiar cheater. Also, evolution generated three new mutually beneficial relationships, including complementary defect rescue between evolved cells and the selection-regime cheater. The rapid evolution of cheater suppression documented here suggests that coevolving social strategies within natural populations of prokaryotes are more diverse and complex than previously appreciated.

Ecological histories determine the success of social exploitation.

Ecological context often modifies biotic interactions, yet effects of ecological history are poorly understood. In experiments with the bacterium Myxococcus xanthus , resource-level histories of genotypes interacting during cooperative multicellular development were found to strongly regulate social fitness. Yet how developmental spore production responded to variation in resource-level histories between interactants differed greatly between cooperators and cheaters; relative-fitness advantages gained by cheating after high-resource growth were generally reduced or absent if one or both parties experienced low-resource growth. Low-resource growth also eliminated facultative exploitation in some pairwise mixes of cooperation-proficient natural isolates that occurs when both strains have grown under resource abundance. Our results contrast with previous studies in which cooperator fitness correlated positively with resource level and suggest that resource-level variation may be important in regulating whether exploitation of cooperators occurs in a natural context.

Impact of a large interprofessional simulation-based training course on communication, teamwork, and safety culture in the operating theatre: A mixed-methods interventional study.

BACKGROUND: Communication and teamwork are critical non-technical skills in the operating theatre. However, prevention of events associated with communication failures by large simulation-based programs remains to be evaluated. The objective was to assess the impact of an interprofessional simulation-based training course on communication, teamwork, checklist adherence, and safety culture. METHODS: We aimed to assess the impact of an interprofessional simulation-based training course on communication, teamwork, checklist adherence, and safety culture. We conducted a before-and-after interventional study based on a mixed-methods approach combining qualitative and quantitative evaluation criteria. The study was performed in a University Hospital with 39 operating theatres operated by 300 providers before (period 1) and after (period 2) an interprofessional simulation-based training course. Surgical procedures were observed, and the primary outcome measure was the rate of procedures with at least one communication failure associated with adverse event. Additional outcomes measured included the rate of other communication failures, checklist adherence, while teamwork and safety culture were assessed by questionnaires. RESULTS: In total, 46 970 communication episodes were analysed during 131 (period 1) and 122 (period 2) surgical procedures. One hundred sixty-four professionals attended 40 simulation-based sessions. The rate of procedures with at least one communication failure associated with adverse events was not significantly different between the 2 periods (38% in period 1 and 43% in period 2; P = 0.47). Nevertheless, the rate of communication failures reduced between period 1 and 2 (8117/28 303 (29%) vs. 3868/18 667 (21%), respectively; P < 0.01). Teamwork scores and checklist adherence increased significantly after the intervention (8.1 (7.2-8.7) in period 1 vs. 8.6 (8.0-9.2) in period 2; P < 0.01 and 17% (0-35 %) in period 1 vs. 44% (26-57 %) in period 2; P < 0.01). Safety culture ratings did not change significantly. CONCLUSION: This study shows that although the rate of procedures with at least one communication failure associated with adverse event (primary endpoint) was not significantly different, a large interprofessional simulation-based training course has a positive effect on communication failures, teamwork, and checklist adherence.

The effect of zolpidem on cognitive function and postural control at high altitude.

Study Objectives: Sleep is altered at high altitude leading many mountaineers to use hypnotics in order to improve sleep efficiency. While after a full night at altitude the short-acting hypnotic zolpidem does not appear to alter cognitive function, residual adverse effects should be considered following early waking-up as performed by mountaineers. We hypothesized that zolpidem intake at high altitude would alter cognitive function 4 hours after drug intake. Methods: In a randomized double-blind controlled cross-over study, 22 participants were evaluated during two nights at sea level and two nights at 3800 m, 4 hours after zolpidem (10 mg) or placebo intake at 10:00 pm. Polygraphic recording was performed until waking-up at 01:30 am. Sleep quality, sleepiness and symptoms of acute mountain sickness were assessed by questionnaires. Two cognitive tasks (Simon task and duration-production task) were performed at rest and during exercise and postural control was evaluated. Results: Zolpidem increased reaction time in all conditions (zolpidem 407 ± 9 ms vs. placebo 380 ± 11 ms; p < 0.001) and error rate in incongruent trials only (10.2 ± 1.1% vs. 7.8 ± 0.8%; p < 0.01) in the Simon task and increased time perception variability (p < 0.001). Zolpidem also altered postural parameters (e.g. center of pressure area, zolpidem 236 ± 171.5 mm2 vs. placebo 119.6 ± 59 mm2; p < 0.001). Zolpidem did not affect apnea-hypopnea index and mean arterial oxygen saturation (p > 0.05) but increased sleep quality (p < 0.001). Zolpidem increased symptoms of acute mountain sickness and sleepiness (p < 0.05). Conclusions: Acute zolpidem intake at high altitude alters cognitive functions and postural control during early wakening which may be deleterious for safety and performances of climbers.

Evolution of dispersal and life history strategies--Tetrahymena ciliates.

BACKGROUND: Considerable attention has focused on how selection on dispersal and other core life-history strategies (reproductive effort, survival ability, colonization capacity) may lead to so-called dispersal syndromes. Studies on genetic variation in these syndromes within species could importantly increase our understanding of their evolution, by revealing whether traits co-vary across genetic lineages in the manner predicted by theoretical models, and by stimulating further hypotheses for experimental testing. Yet such studies remain scarce. Here we studied the ciliated protist Tetrahymena thermophila, a particularly interesting organism due to cells being able to transform into morphs differing dramatically in swim-speed. We investigated dispersal, morphological responses, reproductive performance, and survival in ten different clonal strains. Then, we examined whether life history traits co-varied in the manner classically predicted for ruderal species, examined the investment of different strains into short- and putative long-distance dispersal, while considering also the likely impact of semi-sociality (cell aggregation, secretion of 'growth factors') on dispersal strategies. RESULTS: Very significant among-strain differences were found with regard to dispersal rate, morphological commitment and plasticity, and almost all core life-history traits (e.g. survival, growth performance and strategy), with most of these traits being significantly intercorrelated. Some strains showed high short-distance dispersal rates, high colonization capacity, bigger cell size, elevated growth performance, and good survival abilities. These well performing strains, however, produced fewer fast-swimming dispersal morphs when subjected to environmental degradation than did philopatric strains performing poorly under normal conditions. CONCLUSION: Strong evidence was found for a genetic covariation between dispersal strategies and core life history traits in T. thermophila, with a fair fit of observed trait associations with classic colonizer models. However, the well performing strains with high colonization success and short-distance dispersal likely suffered under a long-distance dispersal disadvantage, due to producing fewer fast-swimming dispersal morphs than did philopatric strains. The smaller cell size at carrying capacity of the latter strains and their poor capacity to colonize as individual cells suggest that they may be adapted to greater levels of dependency on clone-mates (stronger sociality). In summary, differential exposure to selection on competitive and cooperative abilities, in conjunction with selective factors targeting specifically dispersal distance, likely contributed importantly to shaping T. thermophila dispersal and life history evolution.

Performance of point-of-care international normalized ratio measurement to diagnose trauma-induced coagulopathy.

BACKGROUND: Trauma-induced coagulopathy (TIC) is a common feature after severe trauma. Detection of TIC is based upon classic coagulation tests including international normalized ratio (INR) value. Point-of-care (POC) devices have been developed to rapidly measure INR at the bedside on whole blood. The aim of the study was to test the precision of the Coagucheck® XS Pro device for INR measurement at hospital admission after severe trauma. METHODS: We conducted a prospective observational study in a French level I trauma center. From January 2015 to May 2016, 98 patients with a suspicion of a post-traumatic acute hemorrhage had POC-INR measurement on whole blood concomitantly to classic laboratory INR determination (lab-INR) on plasma at hospital admission. The agreement between the two methods in sorting three predefined categories of INR (normal coagulation, moderate TIC and severe TIC) was evaluated using the Cohen's kappa test with a quadratic weighting. The correlation between POC-INR and lab-INR was measured using the Pearson's coefficient. We also performed a Bland and Altman analysis. RESULTS: The agreement between the lab-INR and the POC-INR was moderate (Kappa = 0.45 [95% CI 0.36-0.50]) and the correlation between the two measurements was also weak (Pearson's coefficient = 0.44 [95% CI 0.27-0.59]). Using a Bland and Altman analysis, the mean difference (bias) for INR was 0.22 [95% CI 0.02-0.42], and the standard deviation (precision) of the difference was 1.01. DISCUSSION/CONCLUSION: POC Coagucheck® XS Pro device is not reliable to measure bedside INR. Its moderate agreement with lab-INR weakens the usefulness of such device after severe trauma. TRIAL REGISTRATION: NCT02869737 . Registered 9 August 2016.

Capillary lactate concentration on admission of normotensive trauma patients: a prospective study.

BACKGROUND: Elevated serum blood lactate is an indicator of on-going bleeding in severe trauma patients. Point-of-care (POC) capillary lactate measurement devices may be useful to rapidly assess lactate concentration at the bedside. The aim of this study was to test the diagnostic performance of capillary lactate to predict significant transfusion in normotensive trauma patients. METHODS: We conducted a prospective observational study in one level-I trauma centre. From August 2011 to February 2013, 120 consecutive adult patients with systolic blood pressure (SBP) higher than 90 mmHg were included. Capillary lactate was measured on admission in the trauma bay. The primary outcome was defined as a significant transfusion within the first 48 h. Diagnostic performance was determined using receiver operating characteristic (ROC) curve analysis. We also tested the agreement between capillary lactate and blood lactate concentrations using Bland and Altman analysis. RESULTS: Of the 120 normotensive trauma patients, 30 (25 %) required at least one unit of packed red blood cells (RBC) and 12 (10 %) patients received at least four RBC within the first 48 h. All patients with significant RBC transfusion had capillary lactate higher than 3.5 mmol/l. The area under the ROC curve of capillary lactate on admission to predict transfusion of at least 4 RBC units was 0.68 [95 % CI 0.58 - 0.78]. The average bias between capillary and blood lactate measurements was 2.4 mmol/l with a standard deviation of 3.0 mmol/l (n = 60 patients). CONCLUSIONS: Although a significant association was found between POC lactate concentration and transfusion requirements, the diagnostic performance of capillary lactate measurements was poor. Due to large disagreement between capillary lactate and blood lactate, capillary lactate cannot be considered in the clinical setting. TRIAL REGISTRATION: ClinicalTrials.gov, No. NCT01793428 .