Optimization of the flip angles of narrow-band editing pulses in J-difference edited MRS of lactate at 3T.

PURPOSE: Application of highly selective editing RF pulses provides a means of minimizing co-editing of contaminants in J-difference MRS (MEGA), but it causes reduction in editing yield. We examined the flip angles (FAs) of narrow-band editing pulses to maximize the lactate edited signal with minimal co-editing of threonine. METHODS: The effect of editing-pulse FA on the editing performance was examined, with numerical and phantom analyses, for bandwidths of 17.6-300 Hz in MEGA-PRESS editing of lactate at 3T. The FA and envelope of 46 ms Gaussian editing pulses were tailored to maximize the lactate edited signal at 1.3 ppm and minimize co-editing of threonine. The optimized editing-pulse FA MEGA scheme was tested in brain tumor patients. RESULTS: Simulation and phantom data indicated that the optimum FA of MEGA editing pulses is progressively larger than 180° as the editing-pulse bandwidth decreases. For 46 ms long 17.6 Hz bandwidth Gaussian pulses and other given sequence parameters, the lactate edited signal was maximum at the first and second editing-pulse FAs of 241° and 249°, respectively. The edit-on and difference-edited lactate peak areas of the optimized FA MEGA were greater by 43% and 25% compared to the 180°-FA MEGA, respectively. In-vivo data confirmed the simulation and phantom results. The lesions of the brain tumor patients showed elevated lactate and physiological levels of threonine. CONCLUSION: The lactate MEGA editing yield is significantly increased with editing-pulse FA much larger than 180° when the editing-pulse bandwidth is comparable to the lactate quartet frequency width.

Critical Care Organizations: Building and Integrating Academic Programs.

OBJECTIVE: Academic medical centers in North America are expanding their missions from the traditional triad of patient care, research, and education to include the broader issue of healthcare delivery improvement. In recent years, integrated Critical Care Organizations have developed within academic centers to better meet the challenges of this broadening mission. The goal of this article was to provide interested administrators and intensivists with the proper resources, lines of communication, and organizational approach to accomplish integration and Critical Care Organization formation effectively. DESIGN: The Academic Critical Care Organization Building section workgroup of the taskforce established regular monthly conference calls to reach consensus on the development of a toolkit utilizing methods proven to advance the development of their own academic Critical Care Organizations. Relevant medical literature was reviewed by literature search. Materials from federal agencies and other national organizations were accessed through the Internet. SETTING: The Society of Critical Care Medicine convened a taskforce entitled "Academic Leaders in Critical Care Medicine" on February 22, 2016 at the 45th Critical Care Congress using the expertise of successful leaders of advanced governance Critical Care Organizations in North America to develop a toolkit for advancing Critical Care Organizations. MEASUREMENTS AND MAIN RESULTS: Key elements of an academic Critical Care Organization are outlined. The vital missions of multidisciplinary patient care, safety, and quality are linked to the research, education, and professional development missions that enhance the value of such organizations. Core features, benefits, barriers, and recommendations for integration of academic programs within Critical Care Organizations are described. Selected readings and resources to successfully implement the recommendations are provided. Communication with medical school and hospital leadership is discussed. CONCLUSIONS: We present the rationale for critical care programs to transition to integrated Critical Care Organizations within academic medical centers and provide recommendations and resources to facilitate this transition and foster Critical Care Organization effectiveness and future success.

Arterial blood pressure and heart rate regulation in shock state.

PURPOSE OF REVIEW: Circulatory shock is a complicated problem that carries a high risk of complications and mortality for critically ill patients. The heart rate and blood pressure targets to which a patient in shock should be resuscitated remain a challenge to intensivists. RECENT FINDINGS: While the ideal blood pressure and heart rate in circulatory shock are still not definitive, recent studies have begun to refine these targets. A recent trial comparing a mean arterial pressure target of 80-85 mmHg with a target of 65-70 mmHg showed no difference in mortality, with a decreased need for renal replacement therapy in patients with pre-existing hypertension based on subgroup analysis. Regulation of heart rate was defined by a trial demonstrating that heart rate control in patients with severe sepsis on high-dose norepinephrine with esmolol titration did not result in additional adverse events. SUMMARY: The ideal target blood pressure in the resuscitation of circulatory shock is variable and likely depends on prior blood pressure. Heart rate regulation with ß-blockade appears to be safe in selected patients when accompanied by adequate resuscitation and monitoring.

Enteric Coating and Aspirin Nonresponsiveness in Patients With Type 2 Diabetes Mellitus.

BACKGROUND: A limitation of aspirin is that some patients, particularly those with diabetes, may not have an optimal antiplatelet effect. OBJECTIVES: The goal of this study was to determine if oral bioavailability mediates nonresponsiveness. METHODS: The rate and extent of serum thromboxane generation and aspirin pharmacokinetics were measured in 40 patients with diabetes in a randomized, single-blind, triple-crossover study. Patients were exposed to three 325-mg aspirin formulations: plain aspirin, PL2200 (a modified-release lipid-based aspirin), and a delayed-release enteric-coated (EC) aspirin. Onset of antiplatelet activity was determined by the rate and extent of inhibition of serum thromboxane B2 (TXB2) generation. Aspirin nonresponsiveness was defined as a level of residual serum TXB2 associated with elevated thrombotic risk (<99.0% inhibition or TXB2 >3.1 ng/ml) within 72 h after 3 daily aspirin doses. RESULTS: The rate of aspirin nonresponsiveness was 15.8%, 8.1%, and 52.8% for plain aspirin, PL2200, and EC aspirin, respectively (p < 0.001 for both comparisons vs. EC aspirin; p = 0.30 for comparison between plain aspirin and PL2200). Similarly, 56% of EC aspirin-treated subjects had serum TXB2 levels >3.1 ng/ml, compared with 18% and 11% of subjects after administration of plain aspirin and PL2200 (p < 0.0001). Compared with findings for plain aspirin and PL2200, this high rate of nonresponsiveness with EC aspirin was associated with lower exposure to acetylsalicylic acid (63% and 70% lower geometric mean maximum plasma concentration [Cmax] and 77% and 82% lower AUC0-t [area under the curve from time 0 to the last time measured]) and 66% and 72% lower maximum decrease of TXB2, with marked interindividual variability. CONCLUSIONS: A high proportion of patients treated with EC aspirin failed to achieve complete inhibition of TXB2 generation due to incomplete absorption. Reduced bioavailability may contribute to "aspirin resistance" in patients with diabetes. (Pharmacodynamic Evaluation of PL2200 Versus Enteric-Coated and Immediate Release Aspirin in Diabetic Patients; NCT01515657).

Faculty development for fellows: Developing and evaluating a broad-based career development course for critical care medicine trainees.

PURPOSE: There is no defined training experience to teach the broad range of professional skills needed to transition from critical care trainee to practitioner. We hypothesized that a durable set of career development skills could be created for critical care medicine (CCM) trainees using a novel curriculum defined by both learners and content experts. MATERIALS AND METHODS: We presented a curriculum focused on professional development skills to 8 second-year CCM fellows at a university-based training program. A needs assessment using input from faculty and fellows selected 22 topics for the course. Surveys given precurriculum and postcurriculum and at 3-year follow-up measured the perceived importance of these topics and learner comfort with the skills presented. RESULTS: Average class attendance was 77%. Seven subjects (87.5%) responded to each survey time point. Comfort scores increased from precourse to postcourse survey. Scores were maintained across most content areas from postcourse survey to follow-up. Respondents attributed a high level of importance to receiving training of this kind. CONCLUSIONS: Teaching a broad range of career development skills can result in durable confidence when reinforced by regular use postgraduation. This course fills a critical care educational need, facilitating the transition to practitioner after CCM training.

Practical considerations for the design of sparse-spokes pulses.

Sparse-spokes pulses are 2D slice-selective pulses that effectively mitigate inhomogeneities in the transmitted RF field and reduce unwanted RF artifacts in MR images. Here we consider the practical design of such pulses for high-field MRI and demonstrate limitations of the technique. We analyze the performance of pulses considering input noise as well as other effects such as saturation and T2( *) relaxation. We discuss in detail the correspondence between the reduction of RF inhomogeneities and the fidelity of the input parameters, such as the transmit B1+ field map and combined phase of the main B0 field and eddy-currents. Results include simulations, utilizing 7 T field maps acquired in phantoms and in-vivo, as well as in-vivo experiments. The necessary performance of system hardware components to achieve significant improvements is described.