Continued Validation of Ultrasound Guidance Targeting Tasks: Assessment of Internal Structure.

RATIONALE AND OBJECTIVES: We previously demonstrated validity evidence for our novel ultrasound-guided invasive procedure targeting tasks in the content, response process, relations with other variables, and consequences validity domains. Here, we investigate their internal structure by assessing their interrater, intrarater, and test-retest reliability. METHODS: In this Institutional Review Board approved nonrandomized interventional trial first year medical students performed our previously described dowel and straw ultrasound guidance targeting tasks as a pretest. Afterward, the training group had four weekly 1-hour training sessions. The control group had no further training. Both groups then had a posttest for both tasks. The training group was re-evaluated 2 and 5 months later. Completion time in seconds, errors, and error adjusted time (5 seconds penalty/error) were recorded. Pretest and posttest performance was compared within groups, and the amount of improvement from pretest to posttest was compared between groups. Interrater, intrarater, and test-retest interclass correlation coefficients (ICC) were calculated. RESULTS: Although some improvements from pretest to posttest were seen in both groups, greater improvements were seen in the training group. This skill was retained for at least several months. The interrater and intrarater ICCs were excellent (range 0.83-0.93). The test-retest ICCs were good to excellent in all but one performance measure (0.50-0.78). CONCLUSION: Student performance on the targeting tasks improved markedly after training and persisted for several months. The interrater and intrarater reliability were excellent, while the test-retest reliability was good. This provides additional validity evidence for our novel ultrasound-guided invasive procedure targeting curriculum.

Pore-Scale Hydrodynamics in a Progressively Bioclogged Three-Dimensional Porous Medium: 3-D Particle Tracking Experiments and Stochastic Transport Modeling.

Biofilms are ubiquitous bacterial communities that grow in various porous media including soils, trickling, and sand filters. In these environments, they play a central role in services ranging from degradation of pollutants to water purification. Biofilms dynamically change the pore structure of the medium through selective clogging of pores, a process known as bioclogging. This affects how solutes are transported and spread through the porous matrix, but the temporal changes to transport behavior during bioclogging are not well understood. To address this uncertainty, we experimentally study the hydrodynamic changes of a transparent 3-D porous medium as it experiences progressive bioclogging. Statistical analyses of the system's hydrodynamics at four time points of bioclogging (0, 24, 36, and 48 h in the exponential growth phase) reveal exponential increases in both average and variance of the flow velocity, as well as its correlation length. Measurements for spreading, as mean-squared displacements, are found to be non-Fickian and more intensely superdiffusive with progressive bioclogging, indicating the formation of preferential flow pathways and stagnation zones. A gamma distribution describes well the Lagrangian velocity distributions and provides parameters that quantify changes to the flow, which evolves from a parallel pore arrangement under unclogged conditions, toward a more serial arrangement with increasing clogging. Exponentially evolving hydrodynamic metrics agree with an exponential bacterial growth phase and are used to parameterize a correlated continuous time random walk model with a stochastic velocity relaxation. The model accurately reproduces transport observations and can be used to resolve transport behavior at intermediate time points within the exponential growth phase considered.

Trends in prevalent and incident opioid receipt: an observational study in Veterans Health Administration 2004-2012.

BACKGROUND: Improved understanding of temporal and regional trends may support safe and effective prescribing of opioids. OBJECTIVE: We describe national, regional, and facility-level trends and variations in opioid receipt between fiscal years (FY) 2004 and 2012. DESIGN: Observational cohort study using Veterans Health Administration (VHA) administrative databases. PARTICIPANTS: All patients receiving primary care within 137 VHA healthcare systems during a given study year and receiving medications from VHA one year before and during a given study year. MAIN MEASURES: Prevalent and incident opioid receipt during each year of the study period. KEY RESULTS: The overall prevalence of opioid receipt increased from 18.9% of all veteran outpatients in FY2004 to 33.4% in FY2012, a 76.7% relative increase. In FY2012, women had higher rates of prevalent opioid receipt than men (42.4% vs. 32.9%), and the youngest veterans (18-34 years) had higher prevalent opioid receipt compared to the oldest veterans (≥ 80 years) (47.6% vs. 17.9%). All regions in the United States saw increased rates of prevalent opioid receipt during this time period. Prevalence rates varied widely by facility: in FY2012, the lowest-prescribing facility had a rate of 13.5%, and the highest of 50.8%. Annual incident opioid receipt increased from 8.8% in FY2004 to 10.2% in FY2011, with a decline to 9.8% in FY2012. Incident prescribing increased at some facilities and decreased at others. Facilities with high prevalent prescribing tended to have flat or decreasing incident prescribing rates during the study time frame. CONCLUSIONS: Rates of opioid receipt increased throughout the study time frame, with wide variation in prevalent and incident rates across geographical region, sex, and age groups. Prevalence and incidence rates reflect distinct prescribing practices. Areas with the highest prevalence tended to have lower increases in incident opioid receipt over the study period. This likely reflects facility-level variations in prescribing practices as well as baseline rates of prevalent use. Future work assessing opioid prescribing should employ methodologies to account for and interpret both prevalent and incident opioid receipt.

Effect of near-vision addition lenses on the accuracy of the accommodative response.

BACKGROUND: Addition lenses (adds) are frequently used to increase the accuracy of the near-vision focusing response, and may also play a role in the prevention or retardation of refractive error development. However, following the introduction of such a lens, if the accommodative response is reduced by an amount equal to the magnitude of the near add, then the resulting accommodative error (and degree of retinal defocus) would remain unchanged. METHODS: This study measured the accommodative response in 28 subjects while they viewed a near target binocularly, either through their distance refractive correction alone or this correction combined with a +0.75 D, +1.50 D, +2.00 D, or +2.50 D near add. RESULTS: The mean findings demonstrated a small (0.03 D) lead of accommodation to the near target through the distance correction, and monotonically increasing leads of accommodation with larger adds. Further, the additional lens power required to reduce the accommodative error to zero correlated significantly with the initial accommodative error. CONCLUSIONS: Near addition lenses may actually increase the degree of retinai defocus for individuals who manifest small accommodative errors.

Vergence adaptation and the clinical AC/A ratio.

The accuracy of the gradient technique for measuring the clinical accommodative convergence to accommodation (AC/A) ratio is dependent upon obtaining veridical heterophoria measurements. However, previous studies have demonstrated that the sustained output of slow fusional vergence, which may take several minutes or even hours to decay, can bias heterophoria assessment. In the clinical setting, it is usual to estimate the AC/A ratio after just a few seconds of dissociation. This study investigated whether the slow fusional vergence response alters this crosslink ratio by comparing values of AC/A measured both before and immediately after a 1-hr period of continuous monocular occlusion. Sustained occlusion produced a significant change in near heterophoria in 10 out of the 21 subjects examined, but no significant change in AC/A was observed in either the adapting or non-adapting subgroups. Accordingly, while the sustained output of slow fusional vergence will influence clinical measurements of heterophoria, its presence does not alter the stimulus AC/A ratio significantly.

[Prehospital air ambulance and systemic secondary cerebral damage in severe craniocerebral injuries]. / Médicalisation préhospitalière héliportée et agressions cérébrales secondaires d'origine systémique chez les traumatisés craniocérébraux graves.

Advanced supportive therapy at the site of the accident, associated with direct transfer to a trauma centre increases survival and reduces morbidity rates. Patients with severe head injury, especially those with multiple injuries, often arrive in the emergency department with potentially causes of serious secondary systemic insults to the already injured brain, such as acute anemia (Hematocrit < or = 30%), hypotension (systolic arterial pressure (Pasys) < or = 95 mmHg, 12.7 kPa), hypercapnia (Paco2 > or = 45 mmHg, 6 kPa) and/or hypoxemia (Pao2 < or = 65 mmHg, 8.7 kPa). The incidence of such insults and their impact on mortality were studied in a group of 51 consecutive adults suffering from non penetrating severe head injury (Glasgow score < or = 8, mean age 31 +/- 17 yrs) rescued by a medicalized helicopter. Each patient received medical care on the site of the accident by an anaesthesiologist of a university hospital (UH) complying with an advanced trauma life support protocol including intubation, hyperventilation with FiO2 = 1, restoration of an adequate Pasys and direct transportation to the UH. Mean delay from call to arrival of the rescue team on the site was 15 +/- 5 min. Mean scene time was 32 +/- 10 min in cases not requiring extrication. Nineteen patients (Group I) were admitted without secondary systemic insults to the brain, 13 with isolated head injury, and 6 with multiple injuries, with a low Glasgow Outcome Score (GOS 1-3) of 42% at 3 months. In 32 patients (Group II), despite advanced supportive measures at the scene of the accident and during transportation, one or more secondary systemic insults to the brain were detected upon arrival at the emergency room, one with isolated head injury, 31 with multiple injuries, with a bad GOS of 72% at 3 months. We conclude that: 1) advanced trauma life support prevents from secondary systemic insults in the great majority of isolated severe head injured patients. 2) secondary systemic insults to the already injured brain are frequent in patients with multiple injuries and are difficult to avoid despite rapid aeromedical trauma care, 3) secondary systemic insults to the brain have a catastrophic impact on the outcome of severely head injured patients.