Dexmedetomidine Does Not Affect Evoked Potentials During Spine Surgery.

BACKGROUND: The effect of dexmedetomidine on evoked potentials (EPs) has not been elucidated. We aimed to investigate the effect of dexmedetomidine on somatosensory, motor, and visual EPs. METHODS: After IRB approval, 40 adult patients scheduled for elective spine surgery using total IV anesthesia with propofol and remifentanil were randomly assigned to receive either dexmedetomidine (n = 20) or placebo (n = 20) in a double-blind, placebo-controlled trial. After obtaining informed consent, positioning, and baseline EPs recording, patients were randomly assigned to either IV dexmedetomidine 0.6 µg/kg infused over 10 minutes, followed by 0.6 µg/kg/h, or a corresponding volume of IV normal saline (placebo). EP measures at 60 ± 30 minutes after initiation of study drug were defined as T1 and at 150 ± 30 minutes were defined as T2. Changes from baseline to T1 (primary end point) and from baseline to T2 (secondary end point) in EP latencies (milliseconds) and amplitudes (microvolts) were compared between groups. Data presented as mean ± SD (95% confidence interval). RESULTS: Data from 40 patients (dexmedetomidine: n = 20; age, 54 ± 3 years; 10 males; placebo: n = 20; age, 52 ± 2 years; 5 males) were analyzed. There was no difference between dexmedetomidine versus placebo groups in primary end points: change of somatosensory EPs at T1, latency: 0.01 ± 1.3 (-0.64, 0.65) vs 0.01 ± 1.3 (-0.64, 0.65), P = 0.43 (-1.24, 0.45); amplitude: 0.03 ± 0.14 (-0.06, 0.02) vs -0.01 ± 0.13 (-0.07, 0.05), P = 0.76 (-0.074, 0.1); motor EPs amplitude at T1: 65.1 ± 194.8 (-35, 165; n = 18) vs 109.2 ± 241.4 (-24, 243; n = 16), P = 0.57 (-113.5, 241.57); visual EPs at T1 (right eye), amplitude: 2.3 ± 3.6 (-0.4, 5.1; n = 11) vs 0.3 ± 6.0 (-3.3, 3.9; n = 16), P = 0.38 (-6.7, 2.6); latency N1: 2.3 ± 3.6 (-0.4, 5.1) vs 0.3 ± 6.0 (-3.3, 3.9), P = 0.38 (-6.7, 2.6); latency P1: -1.6 ± 13.4 (-11.9, 8.7) vs -1.4 ± 8.1 (-6.3, 3.5), P = 0.97 (-9.3, 9.7) or secondary end points. There were no differences between right and left visual EPs either at T1 or at T2. CONCLUSIONS: In clinically relevant doses, dexmedetomidine as an adjunct to total IV anesthesia does not seem to alter EPs and therefore can be safely used during surgeries requiring monitoring of EPs.

Nutrition support and deficiencies in children with severe traumatic brain injury.

OBJECTIVE: Adequate nutrition support is considered important to recovery after pediatric traumatic brain injury. The 2003 Pediatric Guidelines recommend initiation of nutrition within 72 hrs after traumatic brain injury. We examined our local experience with nutritional support in severe pediatric traumatic brain injury patients (cases) and non-traumatic brain injury patients (controls). DESIGN: A retrospective review of pediatric patients with severe traumatic brain injury over an 11-yr period (1997-2009) and without traumatic brain injury over a 3-yr period (2007-2009). SETTING: Level I pediatric trauma center pediatric intensive care unit. PATIENTS: Patients with severe pediatric traumatic brain injury (age <15 yrs, Glasgow Coma Scale score of <9) and admitted to the pediatric intensive care unit for >7 days and patients without traumatic brain injury (age <15 yrs, head Abbreviated Injury Scale score of 0) and admitted to pediatric intensive care unit. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Data from 101 severe traumatic brain injury and 92 non-traumatic brain injury patients were analyzed. Traumatic brain injury patients: All received enteral nutrition while 13 (12%) also received parenteral nutrition. Nutrition was started 53 ± 20 hrs (range 12-162) after pediatric intensive care unit admission. Fifty patients (52%) received nutrition within the first 48 hrs, and 83 (82%) received nutrition support within the first 72 hrs. Caloric and protein intakes were 47% and 40% of the goals on pediatric intensive care unit day 7 and 76% and 70% of the goals on pediatric intensive care unit day 14. Caloric and protein goals were met in 26% ± 16% and 18% ± 19% of pediatric intensive care unit stay, respectively. Patients whose intake met nutritional goals on pediatric intensive care unit day 7 had earlier initiation of nutrition support at admission than patients who never met the goals (calorie goal met vs. unmet by day 7, 44 ± 23 hrs vs. 67 ± 31 hrs; p < .001; protein goal met vs. unmet by day 7, 43 ± 17 hrs vs. 65 ± 29 hrs; p = .001). Patients gained 0.6% ± 11% weight by pediatric intensive care unit day 7 and lost 7% ± 11% weight by pediatric intensive care unit day 14. Non-traumatic brain injury patients: The time to start of nutrition for the non-traumatic brain injury group was earlier only for patients with isolated orthopedic injuries (24 ± 6 hrs; p = .02). The average caloric and protein intakes were less for the traumatic brain injury (n = 20) group (caloric 52% ± 16% of goal and protein 42% ± 18% of goal) than for the non-traumatic brain injury (n = 23) group (65% ± 11% of goal and protein 51% ± 20% of goal; both p < .01) for pediatric intensive care unit days 0-7. For pediatric intensive care unit days 8-14, there was no difference in average caloric (82% ± 22% vs. 79% ± 18% of goal) or protein (77% ± 6% vs. 79% ± 7% of goal) between the traumatic brain injury (n = 12) and non-traumatic brain injury (n = 10) groups. Addition of a nutritionist was associated with earlier time to nutrition start (p = .02). CONCLUSIONS: Nutritional support was initiated in most patients within 72 hrs of pediatric intensive care unit admission. Although daily caloric and protein goals were not achieved in the first 2 wks of pediatric intensive care unit stay and nutritional deficiencies were common, earlier start of nutritional support was associated with involvement of a nutritionist and with meeting both caloric and protein goals by pediatric intensive care unit day 7.

The association between fluid balance and outcomes after subarachnoid hemorrhage.

BACKGROUND: We sought to determine the association between early fluid balance and neurological/vital outcome of patients with subarachnoid hemorrhage. METHODS: Hospital admission, imaging, ICU and outcome data were retrospectively collected from the medical records of adult patients with aneurysmal SAH admitted to a level-1 trauma and stroke referral center during a 5-year period. Two groups were identified based on cumulative fluid balance by ICU day 3: (i) patients with a positive fluid balance (n = 221) and (ii) patients with even or negative fluid balance (n = 135). Multivariable logistic regression was used to adjust for age, Hunt-Hess and Fisher scores, mechanical ventilation and troponin elevation (>0.40 ng/ml) at ICU admission. The primary outcome was a composite of hospital mortality or new stroke. RESULTS: Patients with positive fluid balance had worse admission GCS and Hunt-Hess score, and by ICU day 3 had cumulatively received more IV fluids, but had less urine output when compared with the negative fluid balance group. There was no difference in the odds of hospital death or new stroke (adjusted OR: 1.47, 95%CI: 0.85, 2.54) between patients with positive and negative fluid balance. However, positive fluid balance was associated with increased odds of TCD vasospasm (adjusted OR 2.25, 95%CI: 1.37, 3.71) and prolonged hospital length of stay. CONCLUSIONS: Although handling of IV fluid administration was not an independent predictor of mortality or new stroke, patients with early positive fluid balance had worse clinical presentation and had greater resource use during the hospital course.

Increasing the impact of conservation projects.

To assure a future for endangered primates and many other species, we must develop and carry out projects for their conservation as quickly and effectively as possible, even with only limited information about the complex systems of biological, political, social, economic, and cultural factors influencing the conservation situation. Adaptive management, defined as the integration of design, management, and monitoring to systematically test assumptions to learn and adapt, provides practitioners a method for improving strategies to achieve and sustain the desired conservation impact. The Conservation Measures Partnership, a joint venture of conservation NGOs, developed the Open Standards for the Practice of Conservation, a freely available framework that guides practitioners through implementation of best conservation practices. Using this process, project teams are explicit about the assumptions behind the strategies they choose, and thus able to trace their successes and failures back to good or poor theory, implementation, or a combination of the two. The Open Standards comprise five steps that constitute the project management cycle: (1) Conceptualize what you will achieve in the context of where you are working--involves defining your project team, scope, vision, conservation targets, critical threats, and analyzing the situation; (2) Plan your actions and monitoring--involves developing an action plan including goals, strategies, assumptions, objectives, and activities; a monitoring plan including indicators for measuring the status of goals, objectives, and assumptions; and an operational plan specifying the resources needed; (3) Implement your actions and monitoring--includes developing and implementing detailed work plans and ensuring sufficient resources, capacity, and partners; (4) Analyze, use, and adapt--involves managing monitoring data, regular analysis to convert them to useful information, and adapting the project plans accordingly; and (5) Capture and share learning--involves sharing lessons with key external and internal audiences to promote a learning culture.

Etomidate, adrenal function, and mortality in critically ill patients.

BACKGROUND: In critically ill patients, induction with etomidate is hypothesized to be associated with an increased risk of mortality. Previous randomized studies suggest a modest trend toward an increased risk of death among etomidate recipients; however, this relationship has not been measured with great statistical precision. We aimed to test whether etomidate is associated with risk of hospital mortality and other clinical outcomes in critically ill patients. METHODS: We conducted a retrospective cohort study from January 1, 2001, to December 31, 2005, of 824 subjects requiring mechanical ventilation, who underwent adrenal function testing in the ICUs of 2 academic medical centers. The primary outcome was in-hospital mortality, comparing subjects given etomidate (n = 452) to those given an alternative induction agent (n = 372). The secondary outcome was diagnosis of critical illness-related corticosteroid insufficiency following etomidate exposure. RESULTS: Overall mortality was 34.3%. After adjustment for age, sex, and baseline illness severity, the relative risk of death among the etomidate recipients was higher than that of subjects given an alternative agent (relative risk 1.20, 95% CI 0.99-1.45). Among subjects whose adrenal function was assessed within the 48 hours following intubation, the adjusted risk of meeting the criteria for critical illness-related corticosteroid insufficiency was 1.37 (95% CI 1.12-1.66), comparing etomidate recipients to subjects given another induction agent. CONCLUSIONS: In this study of critically ill patients requiring endotracheal intubation, etomidate administration was associated with a trend toward a relative increase in mortality, similar to the collective results of smaller randomized trials conducted to date. If a small relative increased risk is truly present, though previous trials have been underpowered to detect it, in absolute terms the number of deaths associated with etomidate in this high-risk population would be considerable. Large, prospective controlled trials are needed to finalize the role of etomidate in critically ill patients.

Using conceptual models as a planning and evaluation tool in conservation.

Conservation projects are dynamic interventions that occur in complex contexts involving intricate interactions of social, political, economic, cultural, and environmental factors. These factors are constantly changing over time and space as managers learn more about the context within which they work. This complex context poses challenges for planning and evaluating conservation project. In order for conservation managers and evaluation professionals to design good interventions and measure project success, they simultaneously need to embrace and deconstruct contextual complexity. In this article, we describe conceptual models--a tool that helps articulate and make explicit assumptions about a project's context and what a project team hopes to achieve. We provide real-world examples of conceptual models, discuss the relationship between conceptual models and other evaluation tools, and describe various ways that conceptual models serve as a key planning and evaluation tool. These include, for example, that they document assumptions about a project site and they provide a basis for analyzing theories of change. It is impractical to believe that we can completely eliminate detail or dynamic complexity in projects. Nevertheless, conceptual models can help reduce the effects of this complexity by helping us understand it.