Articles from Critical Care medicine

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Lynch, Robert E. MD, PhD, FCCM
Ultrasound is coming to a pediatric intensive care unit near you .[Editorial]
Source
Critical Care Medicine. 37(3):1170-1172, March 2009.


Swiat, Maciej ; Weigele, John ; Hurst, Robert W. ; Kasner, Scott E. ; Pawlak, Mikolaj et al
Middle cerebral artery vasospasm: Transcranial color-coded duplex sonography versus conventional nonimaging transcranial Doppler sonography
Critical Care Medicine. 37(3):963-968, March 2009.
Abstract
Objective: To prospectively compare accuracies of transcranial color-coded duplex sonography (TCCS) and transcranial Doppler sonography (TCD) in the diagnosis of middle cerebral artery (MCA) vasospasm.Design: Prospective blinded head-to-head comparison TCD and TCCS methods using digital subtraction angiography (DSA) as the reference standard.Setting: Department of Radiology in a tertiary university health center in a metropolitan area.Patients: Eighty-one consecutive patients (mean age, 53.9 +/- 13.9 years; 48 women). The indication for DSA was subarachnoid hemorrhage in 71 patients (87.6%), stroke or transient ischemic attack in five patients (6.2%), and other reasons in five patients (6.2%).Interventions: The MCA was graded as normal, narrowed <50%,>50% using DSA. The accuracy of ultrasound methods was estimated by total area (Az) under receiver operator characteristic curve. To compare sensitivities of ultrasound methods, McNemar's test was used with mean velocity thresholds of 120 cm/sec for the detection of less advanced, and 200 cm/sec for the more advanced MCA narrowing.Measurements and Main Results: Angiographic MCA narrowing <=50% was found in 21, and >50% in 10 of 135 arteries. Accuracy of TCCS was insignificantly higher than that of TCD in the detection of <=50% and >50% narrowing, total Az for mean velocity being 0.83 +/- 0.05, 0.77 +/- 0.05, and 0.95 +/- 0.02, 0.86 +/- 0.08, respectively. Sensitivity of TCCS at commonly used threshold of 120 cm/sec for less advanced MCA spasm was significantly better than that of TCD at similar specificity, 55% vs. 39%, p = 0.038, whereas at a threshold of 200 cm/sec used for more advanced spasm, sensitivities and specificities of both methods were not different.Conclusion: The accuracy of TCCS and TCD is similar, but TCCS is more sensitive than TCD in the detection of MCA spasm. Sensitivity of both techniques in the detection of mild and more advanced spasm using 120 cm/sec and 200 cm/sec thresholds, respectively, is poor; however, a larger sample is required to increase precision of our sensitivity estimates.(C) 2009 Lippincott Williams & Wilkins, Inc.


Bodenstein, Marc ; David, Matthias ; Markstaller, Klaus
Principles of electrical impedance tomography and its clinical application. [Review]
Critical Care Medicine. 37(2):713-724, February 2009.
Abstract
Objective: This review outlines the basic principle, in addition to validated and upcoming clinical use of electrical impedance tomography (EIT). EIT generates functional tomograms of the thorax for detection of changes in regional lung aeration. These images allow an intraindividual comparison of changes in regional lung function. Specifically, EIT aims to optimize ventilation therapy in patients with acute lung failure.Data Sources: PubMed: National Library of Medicine and the National Institutes of Health.Study Selection: Studies with the key words "electrical impedance tomography" since 1983.Data Extraction: Qualitative and quantitative results of the studies.Data Synthesis: We summarize basic principles of the technique and subsequent analyzing methods, and give an overview of clinical and scientific questions that can be addressed by EIT.Conclusion: Potential applications in the future as well as limitations of EIT technology are described. In summary, EIT is a promising functional tomography technology on the verge of its clinical application.(C) 2009 Lippincott Williams & Wilkins, Inc.